643 results on '"Botha AM"'
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2. General Louis Botha am Windhoeker Bahnhof
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SWA (Südwestafrika): 1. Weltkrieg / Ereignisse i.d. Schutztruppenzeit, Besatzungsmacht Unionstruppen
3. General Louis Botha am Windhoeker Bahnhof
- Abstract
SWA (Südwestafrika): 1. Weltkrieg / Ereignisse i.d. Schutztruppenzeit, Besatzungsmacht Unionstruppen
4. Legumes and common beans in sustainable diets: nutritional quality, environmental benefits, spread and use in food preparations.
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Lisciani S, Marconi S, Le Donne C, Camilli E, Aguzzi A, Gabrielli P, Gambelli L, Kunert K, Marais D, Vorster BJ, Alvarado-Ramos K, Reboul E, Cominelli E, Preite C, Sparvoli F, Losa A, Sala T, Botha AM, and Ferrari M
- Abstract
In recent decades, scarcity of available resources, population growth and the widening in the consumption of processed foods and of animal origin have made the current food system unsustainable. High-income countries have shifted towards food consumption patterns which is causing an increasingly process of environmental degradation and depletion of natural resources, with the increased incidence of malnutrition due to excess (obesity and non-communicable disease) and due to chronic food deprivation. An urgent challenge is, therefore, to move towards more healthy and sustainable eating choices and reorientating food production and distribution to obtain a human and planetary health benefit. In this regard, legumes represent a less expensive source of nutrients for low-income countries, and a sustainable healthier option than animal-based proteins in developed countries. Although legumes are the basis of many traditional dishes worldwide, and in recent years they have also been used in the formulation of new food products, their consumption is still scarce. Common beans, which are among the most consumed pulses worldwide, have been the focus of many studies to boost their nutritional properties, to find strategies to facilitate cultivation under biotic/abiotic stress, to increase yield, reduce antinutrients contents and rise the micronutrient level. The versatility of beans could be the key for the increase of their consumption, as it allows to include them in a vast range of food preparations, to create new formulations and to reinvent traditional legume-based recipes with optimal nutritional healthy characteristics., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Lisciani, Marconi, Le Donne, Camilli, Aguzzi, Gabrielli, Gambelli, Kunert, Marais, Vorster, Alvarado-Ramos, Reboul, Cominelli, Preite, Sparvoli, Losa, Sala, Botha and Ferrari.)
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- 2024
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5. Host-specific co-evolution likely driven by diet in Buchnera aphidicola.
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Burger NFV, Nicolis VF, and Botha AM
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- Animals, Escherichia coli, Gene Expression Regulation, Diet, Symbiosis genetics, Buchnera genetics, Buchnera metabolism, Aphids genetics, Aphids metabolism
- Abstract
Background: Russian wheat aphid (Diuraphis noxia Kurd.) is a severe pest to wheat, and even though resistance varieties are available to curb this pest, they are becoming obsolete with the development of new virulent aphid populations. Unlike many other aphids, D noxia only harbours a single endosymbiont, Buchnera aphidicola. Considering the importance of Buchnera, this study aimed to elucidate commonalities and dissimilarities between various hosts, to better understand its distinctiveness within its symbiotic relationship with D. noxia. To do so, the genome of the D. noxia's Buchnera was assembled and compared to those of other aphid species that feed on diverse host species., Results: The overall importance of several features such as gene length and percentage GC content was found to be critical for the maintenance of Buchnera genes when compared to their closest free-living relative, Escherichia coli. Buchnera protein coding genes were found to have percentage GC contents that tended towards a mean of ~ 26% which had strong correlation to their identity to their E. coli homologs. Several SNPs were identified between different aphid populations and multiple isolates of Buchnera were confirmed in single aphids., Conclusions: Establishing the strong correlation of percentage GC content of protein coding genes and gene identity will allow for identifying which genes will be lost in the continually shrinking Buchnera genome. This is also the first report of a parthenogenically reproducing aphid that hosts multiple Buchnera strains in a single aphid, raising questions regarding the benefits of maintaining multiple strains. We also found preliminary evidence for post-transcriptional regulation of Buchnera genes in the form of polyadenylation., (© 2024. The Author(s).)
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- 2024
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6. Overexpression of the Small Ubiquitin-Like Modifier protease OTS1 gene enhances drought tolerance in sugarcane (Saccharum spp. hybrid).
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Masoabi M, Burger NFV, Botha AM, Le Roux ML, Vlok M, Snyman S, and Van der Vyver C
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- Peptide Hydrolases metabolism, Ubiquitin metabolism, Drought Resistance, Plants, Genetically Modified metabolism, Endopeptidases metabolism, Ubiquitins genetics, Ubiquitins metabolism, Water metabolism, Droughts, Plant Proteins genetics, Plant Proteins metabolism, Gene Expression Regulation, Plant, Stress, Physiological genetics, Saccharum genetics, Arabidopsis metabolism
- Abstract
Sugarcane is an economically important crop plant across the globe as it is the primary source of sugar and biofuel. Its growth and development are greatly influenced by water availability; therefore, in periods of water scarcity, yields are severely compromised. Small Ubiquitin-Like Modifier (SUMO) proteases play an important role in stress responses by regulating the SUMO-related post-translational modification of proteins. In an attempt to enhance drought tolerance in sugarcane, this crop was genetically transformed with a cysteine protease (OVERLY TOLERANT TO SALT-1; OTS1) from Arabidopsis thaliana using particle bombardment. Transgenic plants were analysed in terms of photosynthetic capacity, oxidative damage, antioxidant accumulation and the SUMO-enrich protein profile was assessed. Sugarcane transformed with the AtOTS1 gene displayed enhanced drought tolerance and delayed leaf senescence under water deficit compared to the untransformed wild type (WT). The AtOTS1 transgenic plants maintained a high relative moisture content and higher photosynthesis rate when compared to the WT. In addition, when the transgene was expressed at high levels, the transformed plants were able to maintain higher stomatal conductance and chlorophyl content under moderate stress compared to the WT. Under severe water deficit stress, the transgenic plants accumulated less malondialdehyde and maintained membrane integrity. SUMOylation of total protein and protease activity was lower in the AtOTS1 transformed plants compared to the WT, with several SUMO-enriched proteins exclusively expressed in the transgenics when exposed to water deficit stress. SUMOylation of proteins likely influenced various mechanisms contributing to enhanced drought tolerance in sugarcane., (© 2023 The Authors. Plant Biology published by John Wiley & Sons Ltd on behalf of German Society for Plant Sciences, Royal Botanical Society of the Netherlands.)
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- 2023
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7. Physiological and biochemical traits positively modulate tissue-specific withanolides and untargeted metabolites in Withania somnifera (L.) dunal under salinity stress.
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Thorat SA, Srivaishnavi M, Kaniyassery A, Padikkal S, Rai PS, Botha AM, and Muthusamy A
- Abstract
Withania somnifera (L.) Dunal (Ashwagandha) has been used in herbal medicines worldwide and in the Indian traditional medicinal system for 3000 years. It is a member of the Solanaceae family distributed across Asia, Africa, Australia, and Europe. Its bioactive secondary metabolite (withanolide) biosynthesis is sensitive to salinity stress, though the mechanism remains unexplored. Therefore, we investigated the effect of Sodium chloride (NaCl) on growth, photosynthesis, biochemical traits, tissue-specific withanolide, and untargeted metabolites in W. somnifera. Ashwagandha plants were raised in pots containing soil mixture and treated with different NaCl concentrations (0 as control, 10, 30, and 50 mM) for one month inside the greenhouse. NaCl stress significantly enhanced withaferin A (WFA) (3.79 mg/g), withanolide A (WA) (0.51 mg/g), and withanone (WN) (0.022 mg/g) at 50 mM NaCl groups in the shoot. Similarly, in the root, a significant increase in WFA (0.19 mg/g) and WN (0.0016 mg/g) were observed at 10 mM, WA (0.059 mg/g) at 30 mM, and withanolide B (WB) (0.013 mg/g) at 50 mM NaCl groups compared to control. LC-MS-based untargeted metabolite profiling revealed 37 differentially accumulated metabolites in all groups. Maximum abundance of glycyl-hydroxyproline (8X) followed by tyrosyl-valine (2X) and 3-hydroxy-beta-ionone (2X) were recorded at 50 mM NaCl groups compared to the control. This study showed for the first time that low NaCl stress enhances the biosynthesis of tissue-specific withanolides through physio-biochemical and metabolites adjustment. Overall, we demonstrated a multifaceted approach for cultivating medicinal crops in salt-affected areas with enhanced bioactive metabolites for healthcare and pharmaceutical industries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)
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- 2023
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8. Corrigendum to "Fast developing Russian wheat aphid biotypes remains an unsolved enigma" [Curr Opin Insect Sci, 45 (2021) 42-52].
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Botha AM
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- 2023
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9. Determining biota succession in a domestic wastewater pond system after treatment with a specific consortium microalgae.
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van den Berg MF, Botha AM, Bierman A, and Oberholster P
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Wastewater stabilization ponds (WSPs) rely on the metabolic activities of the inhabiting microbiota to treat wastewater. A selected consortium of Chlorella vulgaris and Chlorella protothecoides were used to manipulate the natural resident microalgae assemblage to improve the treatment performance of a domestic wastewater pond treatment system in a coastal region. Since information is lacking about the resulting influence on the composition or succession of the phytoplankton or associated microbiota assemblage, the current study aimed to determine how dosing with the microalgae C. vulgaris and C. protothecoides change the efficiency of wastewater effluent treatment, as well as the composition and succession of the natural occurring phytoplankton and microbial assemblage throughout WSP system. After a year of specific microalgae inoculations, the effluent in part complied with the standards set by the Department of Water Affairs and Forestry (DWAF) and the USA, Environmental Protection Agency (EPA). The cyanobacteria Microcystis aeruginosa dominated the sixth (75%) and seventh pond (97%) before the inoculation with C. vulgaris and C. protothecoide commenced. After 12 inoculation events C. vulgaris and C. protothecoides were dominant in ponds three to seven while the dominant microbial groups were Bacteroidetes, Cyanobacteria, Firmicutes, Planctomycetes, Proteobacteria, Spirochaetes, Synergistetes and Verrucomicrobia. After the microalgae treatment, the WSP effluent were more compliant regarding to the set guidelines for effluent than prior to microalgae treatment. Based on the ability of the C. vulgaris and C. protothecoides to improve the effluent water quality, it was evident that the consortium of microalgae can be use improve domestic wastewater effluent in rural nutrient sensitive catchments., Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-022-00840-z., Competing Interests: Conflict of interestThe authors declare no conflicts of interest., (© The Author(s), under exclusive licence to Tehran University of Medical Sciences 2022, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)
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- 2022
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10. The Effects of High CO 2 and Strigolactones on Shoot Branching and Aphid-Plant Compatibility Control in Pea.
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Swiegers HW, Karpinska B, Hu Y, Dodd IC, Botha AM, and Foyer CH
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- Animals, Plant Growth Regulators, Carbon Dioxide pharmacology, Pisum sativum genetics, Zeatin, Ethylenes, Plants, Salicylic Acid, Carbohydrates, Gibberellins pharmacology, Aphids physiology
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Elevated atmospheric CO
2 concentrations (eCO2 ) regulate plant architecture and susceptibility to insects. We explored the mechanisms underpinning these responses in wild type (WT) peas and mutants defective in either strigolactone (SL) synthesis or signaling. All genotypes had increased shoot height and branching, dry weights and carbohydrate levels under eCO2 , demonstrating that SLs are not required for shoot acclimation to eCO2 . Since shoot levels of jasmonic acid (JA) and salicylic acid (SA) tended to be lower in SL signaling mutants than the WT under ambient conditions, we compared pea aphid performance on these lines under both CO2 conditions. Aphid fecundity was increased in the SL mutants compared to the WT under both ambient and eCO2 conditions. Aphid infestation significantly decreased levels of JA, isopentenyladenine, trans -zeatin and gibberellin A4 and increased ethylene precursor ACC, gibberellin A1, gibberellic acid (GA3 ) and SA accumulation in all lines. However, GA3 levels were increased less in the SL signaling mutants than the WT. These studies provide new insights into phytohormone responses in this specific aphid/host interaction and suggest that SLs and gibberellins are part of the network of phytohormones that participate in host susceptibility.- Published
- 2022
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11. Antinutritional factors, nutritional improvement, and future food use of common beans: A perspective.
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Cominelli E, Sparvoli F, Lisciani S, Forti C, Camilli E, Ferrari M, Le Donne C, Marconi S, Juan Vorster B, Botha AM, Marais D, Losa A, Sala T, Reboul E, Alvarado-Ramos K, Waswa B, Ekesa B, Aragão F, and Kunert K
- Abstract
Common bean seeds are an excellent source of protein as well as of carbohydrates, minerals, vitamins, and bioactive compounds reducing, when in the diet, the risks of diseases. The presence of bioactive compounds with antinutritional properties (e.g., phytic acid, lectins, raffinosaccharides, protease inhibitors) limits, however, the bean's nutritional value and its wider use in food preparations. In the last decades, concerted efforts have been, therefore, made to develop new common bean genotypes with reduced antinutritional compounds by exploiting the natural genetic variability of common bean and also applying induced mutagenesis. However, possible negative, or positive, pleiotropic effects due to these modifications, in terms of plant performance in response to stresses or in the resulting technological properties of the developed mutant genotypes, have yet not been thoroughly investigated. The purpose of the perspective paper is to first highlight the current advances, which have been already made in mutant bean characterization. A view will be further provided on future research directions to specifically explore further advantages and disadvantages of these bean mutants, their potential use in innovative foods and representing a valuable genetic reservoir of combinations to assess the true functional role of specific seed bioactive components directly in the food matrix., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cominelli, Sparvoli, Lisciani, Forti, Camilli, Ferrari, Le Donne, Marconi, Juan Vorster, Botha, Marais, Losa, Sala, Reboul, Alvarado-Ramos, Waswa, Ekesa, Aragão and Kunert.)
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- 2022
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12. Whole-body transcriptome mining for candidate effectors from Diuraphis noxia.
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Nicolis VF, Burger NFV, and Botha AM
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- Animals, Russia, Transcriptome, Aphids physiology, Hordeum genetics
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Background: Proteins within aphid saliva play a crucial role as the molecular interface between aphids and their host plants. These salivary effectors modulate plant responses to favour aphid feeding and facilitate infestation. The identification of effectors from economically important pest species is central in understanding the molecular events during the aphid-plant interaction. The Russian wheat aphid (Diuraphis noxia, Kurdjumov) is one such pest that causes devastating losses to wheat and barley yields worldwide. Despite the severe threat to food security posed by D. noxia, the non-model nature of this pest and its host has hindered progress towards understanding this interaction. In this study, in the absence of a salivary gland transcriptome, whole-body transcriptomics data was mined to generate a candidate effector catalogue for D. noxia., Results: Mining the transcriptome identified 725 transcripts encoding putatively secreted proteins amongst which were transcripts specific to D. noxia. Six of the seven examined D. noxia putative effectors, termed DnE's (Diuraphis noxia effectors) exhibited salivary gland-specific expression. A comparative analysis between whole-body D. noxia transcriptome data versus the head and body transcriptomes from three other aphid species allowed us to define a catalogue of transcripts putatively upregulated in D. noxia head tissue. Five of these were selected for RT-qPCR confirmation, and were found to corroborate the differential expression predictions, with a further three confirmed to be highly expressed in D. noxia salivary gland tissue., Conclusions: Determining a putative effector catalogue for D. noxia from whole-transcriptome data, particularly the identification of salivary-specific sequences potentially unique to D. noxia, provide the basis for future functional characterisation studies to gain further insight into this aphid-plant interaction. Furthermore, due to a lack of publicly available aphid salivary gland transcriptome data, the capacity to use comparative transcriptomics to compile a list of putative effector candidates from whole-body transcriptomics data will further the study of effectors in various aphid species., (© 2022. The Author(s).)
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- 2022
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13. Differential Gene Expression and Withanolides Biosynthesis During in vitro and ex vitro Growth of Withania somnifera (L.) Dunal.
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Thorat SA, Kaniyassery A, Poojari P, Rangel M, Tantry S, Kiran KR, Joshi MB, Rai PS, Botha AM, and Muthusamy A
- Abstract
Ashwagandha ( Withania somnifera L. Dunal) is a medicinally important plant with withanolides as its major bioactive compounds, abundant in the roots and leaves. We examined the influence of plant growth regulators (PGRs) on direct organogenesis, adventitious root development, withanolide biosynthetic pathway gene expression, withanolide contents, and metabolites during vegetative and reproductive growth phases under in vitro and ex vitro conditions. The highest shooting responses were observed with 6-benzylaminopurine (BAP) (2.0 mg L
-1 ) + Kinetin (KIN) (1.5 mg L-1 ) supplementation. Furthermore, BAP (2.0 mg L-1 ) + KIN (1.5 mg L-1 ) + gibberellic acid (GA3 ) (0.5 mg L-1 ) exhibited better elongation responses with in vitro flowering. Half-strength MS medium with indole-3-butyric acid (IBA) (1.5 mg L-1 ) exhibited the highest rooting responses and IBA (1.0 mg L-1 ) with highest fruits, and overall biomass. Higher contents of withaferin A (WFA) [∼8.2 mg g-1 dry weight (DW)] were detected in the reproductive phase, whereas substantially lower WFA contents (∼1.10 mg g-1 DW) were detected in the vegetative phase. Cycloartenol synthase ( CAS ) ( P = 0.0025), sterol methyltransferase ( SMT ) ( P = 0.0059), and 1-deoxy-D-xylulose-5-phosphate reductase ( DXR ) ( P = 0.0375) genes resulted in a significant fold change in expression during the reproductive phase. The liquid chromatography-mass spectrometry (LC-MS) analysis revealed metabolites that were common (177) and distinct in reproductive (218) and vegetative (167) phases. Adventitious roots cultured using varying concentrations of indole-3-acetic acid (IAA) (0.5 mg L-1 ) + IBA (1.0 mg L-1 ) + GA3 (0.2 mg L-1 ) exhibited the highest biomass, and IAA (0.5 mg L-1 ) + IBA (1.0 mg L-1 ) exhibited the highest withanolides content. Overall, our findings demonstrate the peculiarity of withanolide biosynthesis during distinct growth phases, which is relevant for the large-scale production of withanolides., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Thorat, Kaniyassery, Poojari, Rangel, Tantry, Kiran, Joshi, Rai, Botha and Muthusamy.)- Published
- 2022
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14. First report of an Anabaena Bory strain containing microcystin-LR in a freshwater body in Africa
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Oberholster, PJ, Jappie, S, Cheng, PH, Botha, AM, and Matthews, MW
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Anabaena ucrainica, heterocysts, microcystin-LR, remote sensing, temperature - Abstract
In South Africa, little is known about the production of microcystin by the genus Anabaena Bory. In April 2012, during a cyanobacterial bloom event in Theewaterskloof Dam, Western Cape province, the plankton was sampled on 10 occasions. The dominant algae belonged to the genus Anabaena, a family of filamentous cyanobacteria known to produce cyanotoxins such as anatoxin-a, harmful to humans and the aquatic foodweb. The specimens isolated lacked the characteristic akinetes and/or heterocysts associated with this genus. Therefore the 16S rRNA gene was Sanger sequenced and a maximum parsimony tree was constructed, confirming its identity as Anabaena ucrainica (Schkorbatow) M. Watanabe. Enzyme-linked immunosorbent assay (ELISA) confirmed the presence of microcystin-LR in the isolated A. ucrainica field sample, while PCR analysis and sequencing further confirmed the presence of mcy genes in this species. It was speculated from the data that prevailing low water-column temperatures and strong gusty winds may have resulted in the lack of akinete or heterocyst production. The Anabaena strain isolated from Theewaterskloof Dam is the first report of a strain containing microcystin-LR belonging to this genus in a freshwater body in Africa.Keywords: Anabaena ucrainica, heterocysts, microcystin-LR, remote sensing, temperature
- Published
- 2016
15. Fast developing Russian wheat aphid biotypes remains an unsolved enigma.
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Botha AM
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- Animals, Ecotype, Aphids physiology, Genetic Variation, Plant Defense Against Herbivory, Triticum genetics
- Abstract
Diuraphis noxia, commonly known as the Russian wheat aphid, is an economically important cereal pest species, highly invasive and reproduces mostly asexually. Remarkably, many new virulent populations continue to develop, despite the lack of genetic diversity in the aphid. Russian wheat aphid is a phloem feeder and is therefore engaged in a continuous arms battle with its cereal host, with the acquisition of virulence central to the breakdown of host resistance. In the review, most attention is given to recent topics about mechanisms and strategies whereby the aphid acquires virulence against its host, with special reference given to the role of noncoding RNA elements, bacteria, and the epigenetic pathway in possibly directing virulence., (Copyright © 2020 The Author. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
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16. EMS Derived Wheat Mutant BIG8-1 ( Triticum aestivum L.)-A New Drought Tolerant Mutant Wheat Line.
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le Roux ML, Burger NFV, Vlok M, Kunert KJ, Cullis CA, and Botha AM
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- Acclimatization genetics, Amino Acids metabolism, Antioxidants metabolism, Chlorophyll metabolism, Ethyl Methanesulfonate toxicity, Mutagens toxicity, Phenotype, Photosystem II Protein Complex metabolism, Plant Breeding, Plant Leaves metabolism, Plant Proteins metabolism, Proteome metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Stress, Physiological genetics, Triticum drug effects, Water metabolism, Droughts, Mutation, Triticum genetics, Triticum physiology
- Abstract
Drought response in wheat is considered a highly complex process, since it is a multigenic trait; nevertheless, breeding programs are continuously searching for new wheat varieties with characteristics for drought tolerance. In a previous study, we demonstrated the effectiveness of a mutant known as RYNO3936 that could survive 14 days without water. In this study, we reveal another mutant known as BIG8-1 that can endure severe water deficit stress (21 days without water) with superior drought response characteristics. Phenotypically, the mutant plants had broader leaves, including a densely packed fibrous root architecture that was not visible in the WT parent plants. During mild (day 7) drought stress, the mutant could maintain its relative water content, chlorophyll content, maximum quantum yield of PSII (Fv/Fm) and stomatal conductance, with no phenotypic symptoms such as wilting or senescence despite a decrease in soil moisture content. It was only during moderate (day 14) and severe (day 21) water deficit stress that a decline in those variables was evident. Furthermore, the mutant plants also displayed a unique preservation of metabolic activity, which was confirmed by assessing the accumulation of free amino acids and increase of antioxidative enzymes (peroxidases and glutathione S-transferase). Proteome reshuffling was also observed, allowing slow degradation of essential proteins such as RuBisCO during water deficit stress. The LC-MS/MS data revealed a high abundance of proteins involved in energy and photosynthesis under well-watered conditions, particularly Serpin-Z2A and Z2B, SGT1 and Calnexin-like protein. However, after 21 days of water stress, the mutants expressed ABC transporter permeases and xylanase inhibitor protein, which are involved in the transport of amino acids and protecting cells, respectively. This study characterizes a new mutant BIG8-1 with drought-tolerant characteristics suited for breeding programs.
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- 2021
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17. Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa
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Oberholster, PJ and Botha, AM
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Hyperscum crust ,reverse-transcription PCR ,mcyA levels ,microcystin ,satellite imaging ,cyanobacteria - Abstract
In this study, we monitored the formation of cyanobacterial hyperscum and crust formation in Lake Hartbeespoort using satellite images and ground monitoring. The hyperscum that formed near the reservoir wall was characterised by a distinctive white surface layer of crust. Hyperscum is the result of exposure of the cells to high radiation, inflicting irreversible damage to the genetic constitution of the upper layer of Microcystis aeruginosa cells. Under the 3 mm thick layer of crust, dark (
- Published
- 2015
18. Factors facilitating sustainable scientific partnerships between developed and developing countries.
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Kunert KJ, Botha AM, Oberholster PJ, Yocgo R, Chimwamurombe P, Vorster J, and Foyer CH
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International scientific partnerships are key to the success of strategic investments in plant science research and the farm-level adoption of new varieties and technologies, as well as the coherence of agricultural policies across borders to address global challenges. Such partnerships result not only in a greater impact of published research enhancing the career development of early and later stage researchers, but they also ensure that advances in plant science and crop breeding technologies make a meaningful contribution to society by brokering acceptance of emerging solutions to the world problems. We discuss the evidence showing that despite a lack of funding, scientists in some African countries make a significant contribution to global science output. We consider the criteria for success in establishing long-term scientific partnerships between scientists in developing countries in Southern Africa ("the South") and developed countries such as the UK ("the North"). We provide our own personal perspectives on the key attributes that lead to successful institutional collaborations and the establishment of sustainable networks of successful "North-South" scientific partnerships. In addition, we highlight some of the stumbling blocks which tend to hinder the sustainability of long-term "North-South" scientific networks. We use this personal knowledge and experiences to provide guidelines on how to establish and maintain successful long-term "North-South" scientific partnerships., Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)
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- 2020
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19. Wheat Line "RYNO3936" Is Associated With Delayed Water Stress-Induced Leaf Senescence and Rapid Water-Deficit Stress Recovery.
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le Roux ML, Burger NFV, Vlok M, Kunert KJ, Cullis CA, and Botha AM
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Random mutagenesis was applied to produce a new wheat mutant (RYNO3926) with superior characteristics regarding tolerance to water deficit stress induced at late booting stage. The mutant also displays rapid recovery from water stress conditions. Under water stress conditions mutant plants reached maturity faster and produced more seeds than its wild type wheat progenitor. Wild-type Tugela DN plants died within 7 days after induction of water stress induced at late booting stage, while mutant plants survived by maintaining a higher relative moisture content (RMC), increased total chlorophyll, and a higher photosynthesis rate and stomatal conductance. Analysis of the proteome of mutant plants revealed that they better regulate post-translational modification (SUMOylation) and have increased expression of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) proteins. Mutant plants also expressed unique proteins associated with dehydration tolerance including abscisic stress-ripening protein, cold induced protein, cold-responsive protein, dehydrin, Group 3 late embryogenesis, and a lipoprotein (LAlv9) belonging to the family of lipocalins. Overall, our results suggest that our new mutant RYNO3936 has a potential for inclusion in future breeding programs to improve drought tolerance under dryland conditions., (Copyright © 2020 le Roux, Burger, Vlok, Kunert, Cullis and Botha.)
- Published
- 2020
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20. DNA Methylation and Demethylation Are Regulated by Functional DNA Methyltransferases and DnTET Enzymes in Diuraphis noxia .
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du Preez PH, Breeds K, Burger NFV, Swiegers HW, Truter JC, and Botha AM
- Abstract
Aphids are economically important insect pests of crops worldwide. Despite resistant varieties being available, resistance is continuously challenged and eventually broken down, posing a threat to food security. In the current study, the epigenome of two related Russian wheat aphid ( Diuraphis noxia , Kurdjumov) biotypes (i.e., SA1 and SAM) that differ in virulence was investigated to elucidate its role in virulence in this species. Whole genome bisulfite sequencing covered a total of 6,846,597,083 cytosine bases for SA1 and 7,397,965,699 cytosine bases for SAM, respectively, of which a total of 70,861,462 bases (SA1) and 74, 073,939 bases (SAM) were methylated, representing 1.126 ± 0.321% (SA1) and 1.105 ± 0.295% (SAM) methylation in their genomes. The sequence reads were analyzed for contexts of DNA methylation and the results revealed that RWA has methylation in all contexts (CpG, CHG and CHH), with the majority of methylation within the CpG context (± 5.19%), while the other contexts show much lower levels of methylation (CHG - ± 0.27%; CHH - ± 0.34%). The top strand was slightly (0.02%) more methylated than the bottom strand. Of the 35,493 genes that mapped, we also analyzed the contexts of methylation of each of these and found that the CpG methylation was much higher in genic regions than in intergenic regions. The CHG and CHH levels did not differ between genic and intergenic regions. The exonic regions of genes were more methylated (±0.56%) than the intronic regions. We also measured the 5mC and 5hmC levels between the aphid biotypes, and found little difference in 5mC levels between the biotypes, but much higher levels of 5hmC in the virulent SAM. RWA had two homologs of each of the DNA methyltransferases 1 ( DNMT1a and DNMT1b ) and DNMT3s ( DNMT3a and DNMT3b ), but only a single DNMT2 , with only the expression of DNMT3 that differed significantly between the two RWA biotypes. RWA has a single ortholog of Ten eleven translocase ( DnTET ) in the genome. Feeding studies show that the more virulent RWA biotype SAM upregulate DnDNMT3 and DnTET in response to wheat expressing antibiosis and antixenosis., (Copyright © 2020 du Preez, Breeds, Burger, Swiegers, Truter and Botha.)
- Published
- 2020
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21. First report of an Anabaena Bory strain containing microcystin-LR in a freshwater body in Africa.
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Oberholster, PJ, Cheng, PH, Jappie, S, Botha, AM, and Matthews, MW
- Subjects
MICROCYSTINS ,HETEROCYSTS ,ANABAENA ,REMOTE sensing ,FRESHWATER biology ,ENZYME-linked immunosorbent assay - Abstract
In South Africa, little is known about the production of microcystin by the genusAnabaenaBory. In April 2012, during a cyanobacterial bloom event in Theewaterskloof Dam, Western Cape province, the plankton was sampled on 10 occasions. The dominant algae belonged to the genusAnabaena, a family of filamentous cyanobacteria known to produce cyanotoxins such as anatoxin-a, harmful to humans and the aquatic foodweb. The specimens isolated lacked the characteristic akinetes and/or heterocysts associated with this genus. Therefore the 16S rRNA gene was Sanger sequenced and a maximum parsimony tree was constructed, confirming its identity asAnabaena ucrainica(Schkorbatow) M. Watanabe. Enzyme-linked immunosorbent assay (ELISA) confirmed the presence of microcystin-LR in the isolatedA. ucrainicafield sample, while PCR analysis and sequencing further confirmed the presence ofmcygenes in this species. It was speculated from the data that prevailing low water-column temperatures and strong gusty winds may have resulted in the lack of akinete or heterocyst production. TheAnabaenastrain isolated from Theewaterskloof Dam is the first report of a strain containing microcystin-LR belonging to this genus in a freshwater body in Africa. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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22. First report of anAnabaenaBory strain containing microcystin-LR in a freshwater body in Africa
- Author
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Oberholster, PJ, primary, Jappie, S, additional, Cheng, PH, additional, Botha, AM, additional, and Matthews, MW, additional
- Published
- 2015
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- View/download PDF
23. Treated acid mine drainage and stream recovery: Downstream impacts on benthic macroinvertebrate communities in relation to multispecies toxicity bioassays.
- Author
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Steyn M, Oberholster PJ, Botha AM, Genthe B, van den Heever-Kriek PE, and Weyers C
- Subjects
- Biological Assay, Environmental Monitoring, Invertebrates, Mining, South Africa, Ecosystem, Water Pollutants, Chemical
- Abstract
The success and long term effectiveness of extensive and expensive engineering solutions to restore streams impacted by Acid Mine Drainage (AMD) is rarely tested. Concentrations of pollutants were measured in water along a longitudinal gradient from a stretch of the Tweelopie stream, South Africa, that receives pH-treated acid mine drainage (AMD) from an abandoned gold mine. The biotoxic effects of treated AMD were determined through macroinvertebrate biotic indices (SASS5) and a battery of toxicity bioassays. These included the L. sativa, A. cepa, D. magna toxicity and Ames mutagenicity tests, as well as an in vitro human liver cancer cell line HepG2. Even though the Tweelopie stream was moderately to severely degraded by multiple anthropogenic stressors, the impact of the treated AMD was masked by the improvement in the system downstream after mixing with the domestic wastewater effluent receiving stream, and subsequent further dilution as a result of the karst springs downstream. The general improvement of the system downstream was clearly shown by the decrease in the ecotoxicity and mutagenicity in relation to the in-stream macroinvertebrates. PCA multivariate analysis successfully displayed associations between the different environmental variables and the decrease in toxicity and subsequent ecosystem improvement downstream. This study indicated that environmental management of AMD remediation should consider long term assessment strategies, including multiple factors, to promote biological ecosystem recovery., (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Published
- 2019
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24. Expression of a Small Ubiquitin-Like Modifier Protease Increases Drought Tolerance in Wheat ( Triticum aestivum L.).
- Author
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le Roux ML, Kunert KJ, van der Vyver C, Cullis CA, and Botha AM
- Abstract
Post-translation modification of proteins plays a critical role in cellular signaling processes. In recent years, the SUMO (Small Ubiquitin-Like Modifier) class of molecules has emerged as an influential mechanism for target protein management. SUMO proteases play a vital role in regulating pathway flux and are therefore ideal targets for manipulating stress-responses. In the present study, the expression of an Arabidopsis thaliana cysteine protease (OVERLY TOLERANT TO SALT-1, OTS1 ) in wheat ( Triticum aestivum L.) has led to improved plant growth under water stress conditions. Transformed wheat (pUBI- OTS1 ) displayed enhanced growth and delayed senescence under water deficit when compared with untransformed Gamtoos-R genotype or plants carrying an empty vector. Transformed pUBI- OTS1 plants also maintained a high relative moisture content (RMC), had a higher photosynthesis rate, and also had a higher total chlorophyll content when compared to untransformed plants or plants carrying an empty vector. SUMOylation of total protein also increased in untransformed plants but not in the At OTS1 transformed plants. Our results suggest that SUMO-proteases may influence an array of mechanisms in wheat to the advantage of the crop to be more tolerant to water stress caused by drought. This is the first report to elucidate SUMOylation effects in the hexaploid crop wheat ( T. aestivum L.).
- Published
- 2019
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25. Deciphering defense strategies that are elucidated in wheat containing different Dn resistance genes
- Author
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Botha AM, Swanevelder ZH, Schultz T, van Eck L, and Lapitan NLV
- Subjects
Wheat breeding ,Wheat genetics - Published
- 2008
26. Different sets of wheat genes are used in Dn7-mediated resistance to feeding by two biotypes of Russian wheat aphid
- Author
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Lapitan NLV, Hess A, Wang H, van Eck L, Scofield S, and Botha AM
- Subjects
Wheat breeding ,Wheat genetics - Published
- 2008
27. New Insights into the Methylation Status of Virulent Diuraphis noxia (Hemiptera: Aphididae) Biotypes.
- Author
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Breeds K, Burger NFV, and Botha AM
- Subjects
- Animals, Sequence Analysis, DNA, South Africa, Aphids genetics, DNA Methylation, Genetic Variation
- Abstract
Epigenetic modifications provide a means for aphid biotype development that a lack of genetic variation, owing to an anholocyclic reproduction lifecycle, fails to do. Here we present data on the DNA methylation status in four South African Russian wheat aphids (RWA), Diuraphis noxia (Kurdjomov) (Hemiptera: Aphididae) biotypes expressing different levels of virulence against its host, Triticum aestivum L. (Poales: Poaceae, Triticeae). The DNA methylation status of these biotypes was determined through the use of methylation-sensitive amplification polymorphism analysis, restriction site-specific fluorescence labeling-a novel technique, and measuring relative global DNA methylation and hydroxymethylation. The least virulent RWA biotype, SA1, was methylated, while biotypes displaying intermediate virulence, SA2 and SA3, exhibited intermediate levels of hemimethylation. The genome of the most virulent RWA biotype, SAM, seems to be hypomethylated, which is likely attained through the process of demethylation.
- Published
- 2018
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28. Genome of Russian wheat aphid an economically important cereal aphid.
- Author
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Burger NFV and Botha AM
- Abstract
Although the hemipterans (Aphididae) are comprised of roughly 50,000 extant insect species, only four have sequenced genomes that are publically available, namely Acyrthosiphon pisum (pea aphid), Rhodnius prolixus (Kissing bug), Myzus persicae (Green peach aphid) and Diuraphis noxia (Russian wheat aphid). As a significant proportion of agricultural pests are phloem feeding aphids, it is crucial for sustained global food security that a greater understanding of the genomic and molecular functioning of this family be elucidated. Recently, the genome of US D. noxia biotype US2 was sequenced but its assembly only incorporated ~ 32% of produced reads and contained a surprisingly low gene count when compared to that of the model/first sequenced aphid, A. pisum . To this end, we present here the genomes of two South African Diuraphis noxia (Kurdjumov, Hemiptera: Aphididae) biotypes (SA1 and SAM), obtained after sequencing the genomes of the only two D. noxia biotypes with documented linked genealogy. To better understand overall targets and patterns of heterozygosity, we also sequenced a pooled sample of 9 geographically separated D. noxia populations (MixIX). We assembled a 399 Mb reference genome (PRJNA297165, representing 64% of the projected genome size 623 Mb) using ± 28 Gb of 101 bp paired-end HiSeq2000 reads from the D. noxia biotype SAM, whilst ± 13 Gb 101 bp paired-end HiSeq2000 reads from the D. noxia biotype SA1 were generated to facilitate genomic comparisons between the two biotypes. Sequencing the MixIX sample yielded ±26 Gb 50 bp paired-end SOLiD reads which facilitated SNP detection when compared to the D. noxia biotype SAM assembly. Ab initio gene calling produced a total of 31,885 protein coding genes from the assembled contigs spanning ~ 399 Mb (GCA_001465515.1)., Competing Interests: The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Published
- 2017
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29. River catchment responses to anthropogenic acidification in relationship with sewage effluent: An ecotoxicology screening application.
- Author
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Oberholster PJ, Botha AM, Hill L, and Strydom WF
- Subjects
- Acids, Agriculture, Ecotoxicology, Mining, Phytoplankton, Sewage analysis, Environmental Monitoring methods, Rivers chemistry, Sewage chemistry, Waste Disposal, Fluid, Water Pollutants, Chemical analysis
- Abstract
Rising environmental pressures on water resources and resource quality associated with urbanisation, industrialisation, mining and agriculture are a global concern. In the current study the upper Olifants River catchment as case study was used, to show that acid mine drainage (AMD) and acid precipitation were the two most important drivers of possible acidification during a four-year study period. Over the study period 59% of the precipitation sampled was classified as acidic with a pH value below 5.6. Traces of acidification in the river system using aquatic organisms at different trophic levels were only evident in areas of AMD point sources. Data gathered from the ecotoxicology screening tools, revealed that discharge of untreated and partially treated domestic sewage from municipal sewage treatment works and informal housing partially mitigate any traces of acidification by AMD and acid precipitation in the main stem of the upper Olifants River. The outcome of the study using phytoplankton and macroinvertebrates as indicator organisms revealed that the high loads of sewage effluent might have played a major role in the neutralization of acidic surface water conditions caused by AMD and acid precipitation. Although previous multi-stage and microcosm studies confirmed the decrease in acidity and metals concentrations by municipal wastewater, the current study is the first to provide supportive evidence of this co-attenuation on catchment scale. These findings are important for integrated water resource management on catchment level, especially in river systems with a complex mixture of pollutants., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2017
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30. Cysteine proteases and wheat (Triticum aestivum L) under drought: A still greatly unexplored association.
- Author
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Botha AM, Kunert KJ, and Cullis CA
- Subjects
- Computational Biology, Models, Biological, Research, Cysteine Proteases metabolism, Droughts, Triticum enzymology, Triticum physiology
- Abstract
Bread wheat (Triticum aestivum L.) provides about 19% of global dietary energy. Environmental stress, such as drought, affects wheat growth causing premature plant senescence and ultimately plant death. A plant response to drought is an increase in protease-mediated proteolysis with rapid degradation of proteins required for metabolic processes. Among the plant proteases that are increased in their activity following stress, cysteine proteases are the best characterized. Very little is known about particular wheat cysteine protease sequences, their expression and also localization. The current knowledge on wheat cysteine proteases belonging to the five clans (CA, CD, CE, CF and CP) is outlined, in particular their expression and possible function under drought. The first successes in establishing an annotated wheat genome database are further highlighted which has allowed more detailed mining of cysteine proteases. We also share our thoughts on future research directions considering the growing availability of genomic resources of this very important food crop. Finally, we also outline future application of developed knowledge in transgenic wheat plants for environmental stress protection and also as senescence markers to monitor wheat growth under environmental stress conditions., (© 2017 John Wiley & Sons Ltd.)
- Published
- 2017
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31. An evaluation of the endocrine disruptive potential of crude oil water accommodated fractions and crude oil contaminated surface water to freshwater organisms using in vitro and in vivo approaches.
- Author
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Truter JC, van Wyk JH, Oberholster PJ, Botha AM, and Mokwena LM
- Subjects
- Animals, Down-Regulation drug effects, Endocrine Disruptors chemistry, Fish Proteins metabolism, Fresh Water chemistry, PPAR gamma metabolism, Petroleum Pollution, Receptors, Androgen metabolism, Saccharomyces cerevisiae drug effects, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Up-Regulation drug effects, Water Pollutants, Chemical chemistry, Xenopus Proteins metabolism, Endocrine Disruptors toxicity, Petroleum toxicity, Tilapia metabolism, Water Pollutants, Chemical toxicity, Xenopus laevis metabolism
- Abstract
Knowledge regarding the potential impacts of crude oil on endocrine signaling in freshwater aquatic vertebrates is limited. The expression of selected genes as biomarkers for altered endocrine signaling was studied in African clawed frog, Xenopus laevis, tadpoles and juvenile Mozambique tilapia, Oreochromis mossambicus, exposed to weathered bunker and unweathered refinery crude oil water accommodated fractions (WAFs). In addition, the expression of the aforementioned genes was quantified in X. laevis tadpoles exposed to surface water collected from the proximity of an underground oil bunker. The (anti)estrogenicity and (anti)androgenicity of crude oil, crude oil WAFs, and surface water were furthermore evaluated using recombinant yeast. Thyroid hormone receptor beta expression was significantly down-regulated in X. laevis in response to both oil WAF types, whereas a further thyroid linked gene, type 2 deiodinase, was up-regulated in O. mossambicus exposed to a high concentration of bunker oil WAF. In addition, both WAFs altered the expression of the adipogenesis-linked peroxisome proliferator-activated receptor gamma in X. laevis. The crude oil and WAFs exhibited antiestrogenic and antiandrogenic activity in vitro. However, O. mossambicus androgen receptor 2 was the only gene, representing the reproductive system, significantly affected by WAF exposure. Estrogenicity, antiestrogenicity, and antiandrogenicity were detected in surface water samples; however, no significant changes were observed in the expression of any of the genes evaluated in X. laevis exposed to surface water. The responses varied among the 2 model organisms used, as well as among the 2 types of crude oil. Nonetheless, the data provide evidence that crude oil pollution may lead to adverse health effects in freshwater fish and amphibians as a result of altered endocrine signaling. Environ Toxicol Chem 2017;36:1330-1342. © 2016 SETAC., (© 2016 SETAC.)
- Published
- 2017
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32. Profiling Diuraphis noxia (Hemiptera: Aphididae) Transcript Expression of the Biotypes SA1 and SAM Feeding on Various Triticum aestivum Varieties.
- Author
-
Burger NFV, Venter E, and Botha AM
- Subjects
- Amplified Fragment Length Polymorphism Analysis, Animals, Aphids physiology, DNA, Complementary genetics, Ecotype, Herbivory, Triticum growth & development, Antibiosis, Aphids genetics, Transcriptome, Triticum physiology
- Abstract
The intimate relationship between an aphid and its host is mediated by the composition of the secreted saliva. In the present study, aphid heads were sampled and transcript profiling conducted after aphids were fed on their preference host and transferred to a variety of preference and nonpreference hosts. It was found that the virulent Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae) biotype SAM was able to selectively up-regulate more transcripts when confronted with feeding on a variety of hosts, than was the case with the less virulent D. noxia biotype SA1, suggesting increased genomic regulation when coping with a stressful environment. Collectively, the observed transcriptomic changes are supported by previous findings that host changes induce significant changes in the proteome of phytophagous hemipterans, unlike in many other entomophagous generalist species. The current data suggest that highly specialized hemipterans may be able to counter plant defenses with inducible salivary transcripts with resulting protein biosynthesis, as demonstrated here., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2017
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- View/download PDF
33. Towards tradable permits for filamentous green algae pollution.
- Author
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de Lange WJ, Botha AM, and Oberholster PJ
- Subjects
- Agriculture methods, Commerce, Environment, Eutrophication, South Africa, Chlorophyta, Water Pollution economics
- Abstract
Water pollution permit systems are challenging to design and implement. Operational systems that has maintained functionality remains few and far between, particularly in developing countries. We present current progress towards developing such a system for nutrient enrichment based water pollution, mainly from commercial agriculture. We applied a production function approach to first estimate the monetary value of the impact of the pollution, which is then used as reference point for establishing a reserve price for pollution permits. The subsequent market making process is explained according to five steps including permit design, terms, conditions and transactional protocol, the monitoring system, piloting and implementation. The monetary value of the impact of pollution was estimated at R1887 per hectare per year, which not only provide a "management budget" for filamentous green algae mitigation strategies in the study area, but also enabled the calculation of a reserve price for filamentous green algae pollution permits, which was estimated between R2.25 and R111 per gram filamentous algae and R8.99 per gram at the preferred state., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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34. Applying genotoxicology tools to identify environmental stressors in support of river management.
- Author
-
Oberholster PJ, Hill L, Jappie S, Truter JC, and Botha AM
- Subjects
- Amplified Fragment Length Polymorphism Analysis, Animals, Biological Assay, Ecosystem, Ecotoxicology, Environmental Monitoring, Environmental Pollution adverse effects, Gastropoda genetics, Gastropoda metabolism, Gene Expression Profiling, Proteins genetics, Proteins metabolism, Rivers, Sewage, Gastropoda drug effects, Water Pollutants, Chemical toxicity
- Abstract
Although bioassay approaches are useful for identifying chemicals of potential concern, they provide little understanding of the mechanisms of chemical toxicity. Without this understanding, it is difficult to address some of the key challenges that currently face aquatic ecotoxicology. To overcome this, the toxicity potential of the water samples was assessed and surviving organisms (Physa acuta) were used for protein activity measurements and gene expression profiling by making use of complementary DNA amplified fragment length polymorphism (cDNA-AFLP) analysis. From the data it was evident that the impacts of specific pollutants (e.g. sewage) on organisms at the cellular level could be identified, and that the expressed stressor genes can be used as bioindicators/markers/genetic signatures or fingerprints during identification of point source pollution. From an ecosystem management point of view these insights could assist with the forecasting and reduction of environmental risks on catchment level by implementing suitable management interventions., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
35. The expression of selected genes linked to metabolic homeostasis in obese pansteatitis-suffering Mozambique tilapia, Oreochromis mossambicus (Peters).
- Author
-
Truter JC, van Wyk JH, Oberholster PJ, Botha AM, and Luus-Powell WJ
- Subjects
- Analysis of Variance, Animals, Fish Diseases etiology, Homeostasis, Lakes chemistry, Linear Models, Metabolic Diseases complications, Metabolic Diseases genetics, Metals analysis, Obesity complications, Obesity genetics, Phytoplankton classification, South Africa, Steatitis etiology, Stramenopiles classification, Tilapia metabolism, Fish Diseases genetics, Metabolic Diseases veterinary, Obesity veterinary, Steatitis genetics, Tilapia genetics
- Abstract
The Oreochromis mossambicus (Peters) population inhabiting Lake Loskop, South Africa, is characterized by a high incidence of obesity and pansteatitis. We investigated potential links between the impaired health of Lake Loskop O. mossambicus and the endocrine system by assessing the expression of selected genes associated with the thyroid and adrenal endocrine axes as well as peroxisome proliferator-activated receptor gamma (pparg). Moreover, contaminant-induced thyroid and/or metabolic modulation in Lake Loskop water was evaluated using juvenile O. mossambicus in laboratory exposures. The expression of thyroid hormone receptor alpha (thra) and type 2 deiodinase (dio2) was higher in Lake Loskop O. mossambicus than fish from another population, suggesting a degree of thyroid disruption. The altered gene expression may be a consequence, rather than cause of obesity. Expression of dio2 and pparg was higher in juvenile O. mossambicus exposed to unfiltered compared to filtered lake water, and our data suggest fasting as causative factor. Micro-organism abundance can therefore be a confounding factor in studies applying molecular markers to test for thyroid modulation by environmental waters. Pansteatitis was not a significant source of variance in the expression of any of the genes investigated, suggesting that the disease is not associated with disrupted endocrine signalling., (© 2014 John Wiley & Sons Ltd.)
- Published
- 2016
- Full Text
- View/download PDF
36. Effect of the Radicle, and Hormones on the Subunit Composition and Molecular Form of Pyrophosphate-Dependent Phosphofructokinase in the Cotyledons of Citrullus lanatus
- Author
-
Botha, AM, primary and Botha, FC, additional
- Published
- 1993
- Full Text
- View/download PDF
37. Phi-class glutathione-S-transferase is involved in Dn1-mediated resistance.
- Author
-
Schultz T, van Eck L, and Botha AM
- Subjects
- Animals, Aphids physiology, Fertility, Gene Silencing, Genes, Plant, Hydrogen Peroxide metabolism, Ascorbate Peroxidases metabolism, Glutathione Transferase metabolism, Herbivory, Superoxide Dismutase metabolism, Triticum physiology
- Abstract
Wheat Dn genes afford resistance to the economically important pest, Diuraphis noxia (Kurdjumov, Russian wheat aphid, RWA) and have been the topic of transcriptomic and proteomic studies aimed at unraveling the pathways involved in resistance. The antibiotic resistance conveyed by Dn1 is characterized by a hypersensitive response (HR) followed by systemic acquired resistance (SAR). Although many candidate genes differentially expressed during the Dn1-mediated resistance response have been identified, few have been functionally verified. The aim of this study was to silence three HR-associated candidate genes in Dn1 containing wheat using virus-induced gene silencing (VIGS): thylakoid-associated ascorbate peroxidase (tAPX), phi-class glutathione-S-transferase (TaGSTF6) and superoxide dismutase Cu/Zn (SOD). D. noxia fertility was used as a measure of antibiotic resistance. Silencing of SOD Cu/Zn had little effect on D. noxia fertility, while increased aphid reproduction was recorded on tAPX- and TaGSTF6-silenced plants. However, tAPX-silencing only affected early measurements and did not have a prolonged effect on resistance. TaGSTF6-silenced plants expressed lowered H2 O2 production in resistant wheat under infestation conditions, suggesting that TaGSTF6 and H2 O2 play an integral role in Dn1-mediated D. noxia resistance in wheat plants., (© 2014 Scandinavian Plant Physiology Society.)
- Published
- 2015
- Full Text
- View/download PDF
38. Silicon-seed priming promotes seed germination under CA-induced autotoxicity by improving sucrose and respiratory metabolism in cucumber (Cucumis sativus L.).
- Author
-
Meng, Xin, Jin, Ning, Jin, Li, Wang, Shuya, Zhao, Wang, Xie, Yandong, Huang, Shuchao, Zhang, Zeyu, Xu, Zhiqi, Liu, Zitong, Lyu, Jian, and Yu, Jihua
- Abstract
Seed germination is one of the critical and sensitive stages of early plant growth, and its process is prevented by cinnamic acid (CA). Silicon (Si) plays a critical role in mitigating abiotic stresses and seed germination in plants, but little is known about its role in seed germination and physiology in CA-stressed cucumber. Here, we conducted experiments in the State Key Laboratory of Aridland Crop Science, Gansu Agricultural University from March to June 2021 to investigate the effects of Si-seed priming on growth, antioxidant capacity, sucrose mobilization and respiratory metabolism during germination under CA stress. Our results showed that seed soaking with Si (9 mmol/L) significantly reduced membrane lipid peroxidation and promoted post-germination growth of cucumber seeds under CA (2.0 mmol/L) stress. Si increased key enzyme activities in sucrose metabolism in CA-stressed seeds after germination, accelerating sucrose degradation and fructose synthesis. Si also enhanced the activities of key enzymes in the glycolytic pathway and pentose phosphate pathway in seeds, as well as in the post-germination tricarboxylic acid cycle, promoting glucose decomposition and ATP synthesis. Principal component analysis significantly separated the CK, Si, and CA + Si treatments from the CA treatment in the first principal component after 48 h of treatment. In addition, qRT-PCR analysis showed that Si induced overexpression of genes related to sucrose and respiratory metabolism in seeds treated with CA for 48 h. In conclusion, our findings provide evidence that Si priming may be an effective method to reverse CA inhibition of cucumber seeds, which effectively improve germination under CA stress by attenuating membrane lipid peroxidation and enhancing sucrose mobilization and respiratory metabolism in cucumber. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Insight in limited research on environmental factors and health implications of toxic cyanobacteria bloom in African freshwater bodies.
- Author
-
Elidrissi El Yallouli, Nadia, Lahrouni, Majida, Mugani, Richard, Oudra, Brahim, and Poté, John
- Subjects
METABOLIC disorders ,HEPATOTOXICOLOGY ,RECREATION ,ALKALOIDS ,ECOLOGY ,PHENOMENOLOGICAL biology ,MITOCHONDRIA ,BACTERIAL toxins ,TOXICOLOGY ,APOPTOSIS ,INFERTILITY ,ECOSYSTEMS ,NUTRITIONAL requirements ,NEURAL transmission ,PEPTIDES ,METABOLITES ,WATER supply ,MOLECULAR structure ,BIBLIOMETRICS ,PUBLIC health ,CHLAMYDIALES ,TEMPERATURE ,TOXICITY testing ,GRAM-negative bacteria ,EPIDEMIOLOGICAL research - Abstract
The rapid rise of cyanotoxins production poses a serious threat to global freshwater ecosystems and has become an important issue of global public health. In Africa, a continent facing serious environmental problems, including poisoning by cyanotoxins, knowledge of the presence and distribution of these toxins remains limited. The primary objective of our review is to assess the occurrence and distribution of cyanotoxins, particularly microcystins (MCs), in African freshwater ecosystems. We aim to analyze the limited but existing literature on this subject, focusing specifically on studies published between 2001 and 2023. Recognizing the scarcity of research on this topic in Africa, we strive to elucidate the emerging patterns of toxin variants and their correlation with environmental variables, such as water temperature and nutrient concentrations. Our investigation reveals MCs as the predominant cyanobacterial secondary metabolites detected across the majority of African freshwater environments where cyanotoxins have been documented. Furthermore, their concentrations have exceeded the World Health Organization's (WHO) provisional guideline for lifetime human exposure through drinking water, which is set at 1 µg L
−1 , as indicated by data in Table 1. Highly significant positive relationships were found between toxin-producing cyanobacteria and environmental factors, in particular water temperature and nutrient concentrations. Given the associated exposure risks in Africa, we recommend frequent monitoring of water quality, the development of guidelines based on international best practice, toxicity tests, and epidemiological investigations to understand the health risks and impacts of cyanotoxin exposure. These measures are essential to both protect the well-being of humans and to ensure the sustainability of African aquatic ecosystems. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
40. A rapid fishery assessment to collect biological information and life-history parameters for rednose labeo Labeo rosae and Mozambique tilapia Oreochromis mossambicus in Loskop Dam, Olifants River, South Africa.
- Author
-
Hlungwani, HA, Marr, SM, Weyl, OLF, Hoffman, AC, Botha, H, and Sara, JR
- Subjects
MOZAMBIQUE tilapia ,FRESHWATER fishes ,NATIVE species ,NATIVE fishes ,FISH mortality ,TILAPIA - Abstract
A 2-week rapid fishery assessment using various sampling gears was conducted to collect life-history data on rednose labeo Labeo rosae and Mozambique tilapia Oreochromis mossambicus in Loskop Dam on the Olifants River, Mpumalanga Province, South Africa. These native species were the two most-abundant fish species caught in the impoundment during the study. Both species displayed a bimodal population size distribution comprised of recent recruits and large-sized individuals. Isometric growth (b value ∼3), an asymptotic length (L
∞ ) of 447 mm, and length at 50% sexual maturity (Lm50 ) of 198 mm were estimated for L. rosae. Isometric growth, L∞ of 451 mm, and Lm50 of 124 mm were estimated for O. mossambicus. This rapid assessment at Loskop Dam produced sets of life-history parameters comparable to those previously reported for these two species in Flag Boshielo Dam, ∼80 km downstream. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
41. The complete mitochondrial genome of Periphyllus koelreuteriae (Takahashi, 1919) (Hemiptera: Aphididae: Chaitophorinae).
- Author
-
Li, Cailing, Liu, Hao, Jiang, Liyun, Qiao, Gexia, and Chen, Jing
- Subjects
MITOCHONDRIAL DNA ,WHOLE genome sequencing ,APHID control ,PHYLOGENY ,APHIDS ,TRANSFER RNA - Abstract
We sequenced the complete mitochondrial genome of the aphid Periphyllus koelreuteriae. It is 16,828 bp long and includes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosome RNA genes (rRNAs), a control region, and a repeat region. The control region contains a 273-bp repeat motif repeated 2.3 times. The species-specific repeat region between trnE and trnF comprises two 340-bp repeat units. The maximum-likelihood tree based on all 37 mitochondrial genes indicated a close relationship between P. koelreuteriae and Periphyllus diacerivorus. This study provides a valuable mitogenomic resource for future research on Chaitophorinae phylogeny and P. koelreuteriae diversification. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Evaluation of the water quality of an artificial inter-andean lake in northern Peru.
- Author
-
Rascón, Jesús, Cotrina Rioja, Lesvi T., Huaman Vilca, Shanndy, Santa Cruz Guerrero, Carlos, Altamirano-Oporto, Juan Carlos, Salas López, Rolando, and Silva López, Jhonsy Omar
- Subjects
BODIES of water ,TRACE elements in water ,WATER quality ,ENVIRONMENTAL quality ,TROPICAL dry forests ,TRACE elements - Abstract
Lake Burlan, a lentic ecosystem artificially created by untreated runoff from adjacent rice fields, is located in the Amazon region within the dry forests of northern Peru. This body of water plays a fundamental role in agriculture and recreational activities in the area, which are fundamental to the local economy. This research aimed to evaluate the water quality of Lake Burlan using the Water Quality Index of Peru (WQI-PE). In addition, both spatial and depth variations of limnological parameters and trace elements were determined. The WQI-PE was calculated at seven sampling stations at two depths (surface level and one meter), using 18 limnological parameters and nine trace elements. The WQI-PE assessment indicated that the lake water quality ranged from poor to fair for both depths. Statistical analysis showed that nine limnological parameters and five trace elements showed spatial differences across seven sampling stations, while three limnological parameters and two trace elements showed depth-dependent variations. Concentrations of arsenic, cadmium, mercury, and lead were in exceedance of the national and international standards on environmental water quality. Therefore, the water quality of Lake Burlan is affected mainly by the impact of the surrounding rice fields and recreational activities. This research establishes a starting point for future monitoring to assist in the implementation of prevention and mitigation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Near-isogenic lines of Triticum aestivum with distinct modes of resistance exhibit dissimilar transcriptional regulation during Diuraphis noxia feeding.
- Author
-
Botha AM, van Eck L, Burger NF, and Swanevelder ZH
- Abstract
Russian wheat aphid (Diuraphis noxia, Kurdjumov) feeding on susceptible Triticum aestivum L. leads to leaf rolling, chlorosis and plant death - symptoms not present in resistant lines. Although the effects of several D. noxia (Dn) resistance genes are known, none have been isolated or characterized. Wheat varieties expressing different Dn genes exhibit distinct modes of D. noxia resistance, such as antibiosis (Dn1), tolerance (Dn2), and antixenosis (Dn5). However, the mechanism whereby feeding aphids are perceived, and how subsequent transcriptional responses are partitioned into resistance categories, remains unclear. Here we report on downstream events in near-isogenic wheat lines containing different Dn genes after D. noxia biotype SA1 feeding. Transcripts involved in stress, signal transduction, photosynthesis, metabolism and gene regulation were differentially regulated during D. noxia feeding. Expression analyses using RT-qPCR and RNA hybridization, as well as enzyme activity profiling, provide evidence that the timing and intensity of pathways induced are critical in the development of particular modes of resistance. Pathways involved include the generation of kinase signalling cascades that lead to a sustained oxidative burst, and a hypersensitive response that is active during antibiosis. Tolerance is a passive resistance mechanism that acts through repair or de novo synthesis of photosystem proteins. Results further suggest that ethylene-mediated pathways are possibly involved in generating volatile compounds and cell wall fortification during the antixenosic response., (© 2014. Published by The Company of Biologists Ltd.)
- Published
- 2014
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44. The potential of selected macroalgal species for treatment of AMD at different pH ranges in temperate regions.
- Author
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Oberholster PJ, Cheng PH, Botha AM, and Genthe B
- Subjects
- Cold Temperature, Glutathione Transferase metabolism, Hydrogen-Ion Concentration, South Africa, Species Specificity, Chlorophyta metabolism, Metals metabolism, Mining methods, Water Pollutants, Chemical chemistry, Water Purification methods
- Abstract
The metal bioaccumulation potential of selected macroalgae species at different pH ranges was study for usage as part of a possible secondary passive acid mine drainage (AMD) treatment technology in algae ponds. Two separate studies were conducted to determine the suitability of macroalgae for passive treatment when metabolic processes in macrophytes and microorganisms in constructed wetlands decrease during winter months. In the field study, the bioconcentration of metals (mg/kg dry weight) measured in the benthic macroalgae mats was in the following order: site 1. Oedogonium crassum Al > Fe > Mn > Zn; site 2. Klebsormidium klebsii, Al > Fe > Mn > Zn; site 3. Microspora tumidula, Fe > Al > Mn > Zn and site 4. M. tumidula, Fe > Mn > Al > Zn. In the laboratory study, cultured macroalgae K. klebsii, O. crassum and M. tumidula isolated from the field sampling sites were exposed to three different pH values (3, 5 and 7), while bioaccumulation of the metals, Al, Fe, Mn and Zn and glutathione S-transferase (GST) activity were measured in the different selected algae species at a constant water temperature of 14 °C. Bioaccumulation of Al was the highest for O. crassum followed by K. klebsii and M. tumidula (p < 0.0001). From the study it was evident that the highest metal bioaccumulation occurred in the macroalgae O. crassum at all three tested pH values under constant low water temperature., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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45. The transcriptional network of WRKY53 in cereals links oxidative responses to biotic and abiotic stress inputs.
- Author
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Van Eck L, Davidson RM, Wu S, Zhao BY, Botha AM, Leach JE, and Lapitan NL
- Subjects
- Abscisic Acid metabolism, Gene Regulatory Networks, Oryza metabolism, Oryza radiation effects, Oxidative Stress, Plant Immunity genetics, Plant Proteins metabolism, Promoter Regions, Genetic, Protein Binding, Protein Interaction Domains and Motifs, Sequence Homology, Nucleic Acid, Signal Transduction, Transcription Factors metabolism, Triticum metabolism, Triticum radiation effects, Ultraviolet Rays, Gene Expression Regulation, Plant, Oryza genetics, Plant Proteins genetics, Transcription Factors genetics, Transcription, Genetic, Triticum genetics
- Abstract
The transcription factor WRKY53 is expressed during biotic and abiotic stress responses in cereals, but little is currently known about its regulation, structure and downstream targets. We sequenced the wheat ortholog TaWRKY53 and its promoter region, which revealed extensive similarity in gene architecture and cis-acting regulatory elements to the rice ortholog OsWRKY53, including the presence of stress-responsive abscisic acid-responsive elements (ABRE) motifs and GCC-boxes. Four proteins interacted with the WRKY53 promoter in yeast one-hybrid assays, suggesting that this gene can receive inputs from diverse stress-related pathways such as calcium signalling and senescence, and environmental cues such as drought and ultraviolet radiation. The Ser/Thr receptor kinase ORK10/LRK10 and the apoplastic peroxidase POC1 are two downstream targets for regulation by the WRKY53 transcription factor, predicted based on the presence of W-box motifs in their promoters and coregulation with WRKY53, and verified by electrophoretic mobility shift assay (EMSA). Both ORK10/LRK10 and POC1 are upregulated during cereal responses to pathogens and aphids and important components of the oxidative burst during the hypersensitive response. Taken with our yeast two-hybrid assay which identified a strong protein-protein interaction between microsomal glutathione S-transferase 3 and WRKY53, this implies that the WRKY53 transcriptional network regulates oxidative responses to a wide array of stresses.
- Published
- 2014
- Full Text
- View/download PDF
46. Hypervirulent Diuraphis noxia (Hemiptera: Aphididae) biotype SAM avoids triggering defenses in its host (Triticum aestivum) (Poales: Poaceae) during feeding.
- Author
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Botha AM, Burger NF, and Van Eck L
- Subjects
- Animals, Aphids genetics, Feeding Behavior, Food Chain, Triticum enzymology, Triticum genetics, Antibiosis, Aphids physiology, Triticum physiology
- Abstract
In the molecular arms race between aphids and plants, both organisms rely on adaptive strategies to outcompete their evolutionary rival. In the current study, we investigated the difference in elicited defense responses of wheat (Triticum aestivum L.) near-isogenic lines with different Dn resistance genes, upon feeding by an avirulent and hypervirulent Diuraphis noxia Kurdjumov biotype. After measuring the activity of a suite of enzymes associated with plant defense, it became apparent that the host does not recognize the invasion by the hypervirulent aphid because none of these were induced, while feeding by the avirulent biotype did result in induction of enzyme activity. Genomic plasticity in D. noxia may be a likely explanation for the observed differences in virulence between D. noxia biotype SA1 and SAM, as demonstrated in the current study.
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- 2014
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47. The impacts of neutralized acid mine drainage contaminated water on the expression of selected endocrine-linked genes in juvenile Mozambique tilapia Oreochromis mossambicus exposed in vivo.
- Author
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Truter JC, va Wyk JH, Oberholster PJ, and Botha AM
- Subjects
- Acids chemistry, Animals, Endocrine System drug effects, Fish Proteins genetics, Rivers chemistry, Tilapia metabolism, Gene Expression Regulation drug effects, Mining, Tilapia genetics, Water Pollutants, Chemical toxicity
- Abstract
Acid mine drainage (AMD) is a global environmental concern due to detrimental impacts on river ecosystems. Little is however known regarding the biological impacts of neutralized AMD on aquatic vertebrates despite excessive discharge into watercourses. The aim of this investigation was to evaluate the endocrine modulatory potential of neutralized AMD, using molecular biomarkers in the teleost fish Oreochromis mossambicus in exposure studies. Surface water was collected from six locations downstream of a high density sludge (HDS) AMD treatment plant and a reference site unimpacted by AMD. The concentrations of 28 elements, including 22 metals, were quantified in the exposure water in order to identify potential links to altered gene expression. Relatively high concentrations of manganese (~ 10mg/l), nickel (~ 0.1mg/l) and cobalt (~ 0.03 mg/l) were detected downstream of the HDS plant. The expression of thyroid receptor-α (trα), trβ, androgen receptor-1 (ar1), ar2, glucocorticoid receptor-1 (gr1), gr2, mineralocorticoid receptor (mr) and aromatase (cyp19a1b) was quantified in juvenile fish after 48 h exposure. Slight but significant changes were observed in the expression of gr1 and mr in fish exposed to water collected directly downstream of the HDS plant, consisting of approximately 95 percent neutralized AMD. The most pronounced alterations in gene expression (i.e. trα, trβ, gr1, gr2, ar1 and mr) was associated with water collected further downstream at a location with no other apparent contamination vectors apart from the neutralized AMD. The altered gene expression associated with the "downstream" locality coincided with higher concentrations of certain metals relative to the locality adjacent to the HDS plant which may indicate a causative link. The current study provides evidence of endocrine disruptive activity associated with neutralized AMD contamination in regard to alterations in the expression of key genes linked to the thyroid, interrenal and gonadal endocrine axes of a teleost fish species., (© 2013 Published by Elsevier Inc.)
- Published
- 2014
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48. An ecotoxicological screening tool to prioritise acid mine drainage impacted streams for future restoration.
- Author
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Oberholster PJ, Genthe B, Hobbs P, Cheng PH, de Klerk AR, and Botha AM
- Subjects
- Animals, Biological Assay, Daphnia, Ecotoxicology, Metals analysis, Metals toxicity, Toxicity Tests, Water Pollutants, Chemical analysis, Environmental Monitoring methods, Mining, Rivers chemistry, Water Pollutants, Chemical toxicity
- Abstract
Streams impacted by acid mine drainage (AMD) typically present water exhibiting low pH and high metal concentrations. These factors result in the environmental degradation of watercourses. The objective of this study was to develop and evaluate an ecotoxicological screening tool (EST) to prioritise future remediation of streams impacted by AMD. The Bloubank stream drainage system in South Africa, served as study area for this purpose. In the initial EST development phase physicochemical variables were assessed while in the second phase, epilithic filamentous green algae biomass (chl-a mg m(-2)), diatoms and filamentous green algae community structures were employed as bioindicators as well as Daphnia magna toxicity assays. Using a weight of evidence approach, the first three sites receiving AMD were critically and seriously modified, followed by site 4 that was modified. Sites 1-3 with EST scores ≤70% were assessed as priority candidates for future restoration., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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49. Schmallenberg virus--is it present in South Africa?
- Author
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Leask R, Botha AM, and Bath GF
- Subjects
- Animals, Bunyaviridae Infections epidemiology, Bunyaviridae Infections virology, Congenital Abnormalities epidemiology, Congenital Abnormalities virology, Female, Pregnancy, Sheep, Sheep Diseases epidemiology, Sheep Diseases virology, South Africa epidemiology, Bunyaviridae Infections veterinary, Congenital Abnormalities veterinary, Orthobunyavirus classification, Orthobunyavirus isolation & purification, Sheep Diseases congenital
- Abstract
In July 2006, a case of two out of three lambs born to one ewe in a flock of 45 had signs that, in retrospect, were possibly consistent with Schmallenberg virus infection. This occurred in the Onderstepoort area (Gauteng Province) but a definitive diagnosis was not made. Then, in May 2008, a farmer in the Delmas area (Mpumalanga Province) reported that deformed lambs had been born to several ewes in the flock. Six of the approximately 50 mated ewes gave birth to lambs showing varying degrees of arthrogryposis, torticollis, kyphosis, mandibular brachygnathia and hydrocephalus. Of these, only two were born alive but they died within a few hours. Blood was collected from the ewes with deformed lambs, a random sample of ewes that had given birth to normal lambs and a lamb that was normal but had a twin that was deformed. The samples were tested for Wesselsbron and Akabane antibodies using a complement fixation test and a haemagglutination/haemagglutination inhibition test that were available at that time. Bluetongue virus antibodies were also tested for using a commercial Enzyme-linked immunosorbent assay (ELISA) test. All samples showed negative results for all diseases tested. At the time Rift Valley fever virus had not been diagnosed in that region for many years and so it was not included in the testing. It is unlikely that this was the cause as no liver pathology was detected on postmortem examination of the lambs and no adult ewes had died. The farmer reported that another farm just a few kilometres away experienced the same deformities in some of their lambs but this farm was not investigated. During investigation it was thought that the cause was possibly a new strain of Akabane virus, although there was no way to confirm it. However, with the recent discovery of the Schmallenberg virus, it is possible that this virus has been present in South Africa for at least the last four years without being identified.
- Published
- 2013
- Full Text
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50. Assessment of Benthic Meiofauna in Multi-Stressed Environment of a Tropical Estuary: a Case Study Using Low Taxonomic Resolution Data.
- Author
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Sautya, Sabyasachi, Gaikwad, Santosh, Ram, Anirudh, Basu, Udita, Molla, Nageswar Rao, and Chatterjee, Tapas
- Published
- 2025
- Full Text
- View/download PDF
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