Search

Environmental microplastic accumulation can lead to a range of problems and the potential loss of ecosystem services. However, the impacts of microplastics on sediment environmental properties and microbial ecosystems remain unclear. Therefore, this article aimed to better elucidate the effects of microplastics on sediment physicochemical properties, enzymatic activities and the diversity and composition of sediment microbial communities. We conducted a 60-day sediment-incubation experiment using sediments with three concentrations (2%, 5%, and 10%, w/w) and two types (polyethylene (PE) and polyvinyl chloride (PVC)) of microplastics (550 μm) in a climate-controlled chamber. The addition of both PE and PVC microplastics reduced sediment catalase, polyphenol oxidase (PO), and urease activities, and decreased physicochemical indicators, including total organic carbon (TOC), total nitrogen (TN), and pH value. In addition, microplastics reduced bacterial community diversity and inhibited the recovery of community richness, implying that microplastics may compete with sediment microorganisms for niches. Stronger effects were generally detected under a high microplastic concentration (10%), reflecting the influence of the concentration of microplastic exposure on the bacterial community. The dominant bacterial phyla were Chloroflexi, Proteobacteria, Bacteroidota, Firmicutes, and Actinobacteriota, and the relative abundances of Proteobacteria, and Bacteroidota significantly increased in the microplastic treatments during the late incubation period, indicating that microplastic addition may have improved nutritional conditions later in the incubation process. Structural equation modeling indicated that shifts in PO activity had a significant correlation with changes in Proteobacteria abundance (P 0.01), and important drivers affecting the dissimilarity of Bacteroidota abundance were the changes of TN content and catalase activity (P 0.05). These results indicated that microplastics with diverse characteristics affected the environmental properties of the sediment, while the physicochemical properties and enzymatic activity of the sediment could directly or indirectly exert different impacts on the dominant bacteria. This study can provide a theoretical basis for the ecological effects of microplastic contamination.

Background Clip domain serine proteases (CLIPs), a very diverse group of proteolytic enzymes, play a crucial role in the innate immunity of insects. Innate immune responses are the first line of defense in mosquitoes against the invasion of pathogenic microorganisms. The Toll pathway, immunodeficiency (IMD) pathway and melanization are the main processes of innate immunity in Aedes aegypti. CLIPS are classified into five subfamilies—CLIPA, CLIPB, CLIPC, CLIPD, and CLIPE—based on their sequence specificity and phylogenetic relationships. We report the functional characterization of the genes that code for two CLIPs in Ae. aegypti (Ae): Ae-CLIPB15 and Ae-CLIPB22. Methods Clustal Omega was used for multiple amino acid sequence alignment of Ae-CLIPB15 and Ae-CLIPB22 with different CLIP genes from other insect species. The spatiotemporal expression profiles of Ae-CLIPB15 and Ae-CLIPB22 were examined. We determined whether Ae-CLIPB15 and Ae-CLIPB22 respond to microbial challenge and tissue injury. RNA interference (RNAi) was used to explore the function of Ae-CLIPB15 and Ae-CLIPB22 in the defense of Ae. aegypti against bacterial and fungal infections. The expression levels of nuclear factor kappa B (NF-κB) transcription factors REL1 and REL2 in the Toll pathway and IMD pathway after bacterial infection were investigated. Finally, the change in phenoloxidase (PO) activity in Ae-CLIPB15 and Ae-CLIPB22 knockdown adults was investigated. Results We performed spatiotemporal gene expression profiling of Ae-CLIPB15 and Ae-CLIPB22 genes in Ae. aegypti using quantitative real-time polymerase chain reaction. These genes were expressed in different stages and tissues. The messenger RNA (mRNA) levels for both genes were also up-regulated by Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus and fungal Beauveria bassiana infections, as well as in the tissue injury experiments. RNAi-mediated knockdown of Ae-CLIPB15 led to a significant decrease of PO activity in the hemolymph of Ae. aegypti, while other RNAi experiments revealed that both Ae-CLIPB15 and Ae-CLIPB22 were involved in immune defense against bacterial and fungal infections. The mRNA expression of NF-κB transcription factors REL1 and REL2 in the Toll pathway and IMD pathway differed between Ae-CLIPB15 and Ae-CLIPB22 knockdown mosquitoes infected with bacteria and wild type mosquitoes infected with bacteria. Conclusions Our findings suggest that Ae-CLIPB15 and Ae-CLIPB22 play a critical role in mosquito innate immunity, and that they are involved in immune responses to injury and infection. Their regulation of transcription factors and PO activity indicates that they also play a specific role in the regulation of innate immunity. Graphical Abstract

In this study, the co–application of chitosan and tetramycin against kiwifruit soft rot and its effects on the disease resistance, growth, quality and aroma of kiwifruit were investigated. The results show that chitosan could effectively enhance tetramycin against soft rot of kiwifruit with the field control efficacy of 85.33% for spraying chitosan 100 time + 0.3% tetramycin AS 5000–time dilution liquid, which was higher than 80.99% for 0.3% tetramycin AS 5000–time dilution liquid and significantly (p &lt, 0.01) higher than 40.66% for chitosan 100–time dilution liquid. Chitosan could significantly (p &lt, 0.05) improve the promoting effects of tetramycin on total phenolics, total flavonoids, SOD activity of kiwifruit compared to tetramycin during storage for 0–28 days and enhance the disease resistance of kiwifruit. Moreover, the co–application of chitosan and tetramycin was more effective than tetramycin or chitosan alone in enhancing fruit growth, improving fruit quality and increasing fruit aroma. This study highlights that chitosan can be used as an adjuvant to enhance tetramycin against soft rot of kiwifruit and promote tetramycin’s improvement for the single fruit volume and weight, vitamin C, soluble sugar, soluble solid, dry matter, soluble protein, titratable acidity and aroma of kiwifruit.

The purpose of the study was to assess the effect of static and multi-pulsed high pressure processing (HPP) (300-600 MPa, 5-15 min) on the changes in the polyphenolic profile, polyphenoloxidase (PPO) and peroxidise (POD) activities and colour of apple juice. Content of (-)-epicatechin, procyanidin B2, phloretin isomers and phloridzin was detected using Triple-TOF-LC-MS/MS analysis. After HPP treatment, 1,2- disinapoyl-2-feruloylgentiobiose was detected, whereas sinapoyl glucose was degraded after applying 450 MPa and 600 MPa in single pulse, therefore indicating sensitivity of this compound to high pressure and/or polymerization caused by enzymatic reactions. The highest inactivation of PPO (95%) and POD (26%) was observed at 600 MPa. The multi-pulsed HPP (300 MPa × 3 pulses) resulted in higher reduction in oxidoreductive enzyme activity than higher pressure in single pulse (450 MPa). Statistical changes in the colour parameters were observed in pressurized samples, with the lowest ΔE values for 300 MPa × 3 pulses.

Short vase life, capitulum wilting, neck bending, and postharvest chilling injury (CI) are major disorders have negative impact on quality and marketing of gerbera cut flowers. Low storage temperatures prolonging the vase life, but on the other hand leads serious CI which decreases the quality and consumer preferences. Spermine (SPER) and γ-aminobutyric acid (GABA) were identified as anti-aging factors delay the senescence and elevate the chilling tolerance in many species. Greenhouse-grown gerbera cv. ‘Stanza’ sprayed with 2 mM SPER and 1 mM GABA twice (2 T) or thrice (3 T). Cut flowers were stored at 1.5 °C and 8 °C postharvest to study the effects of GABA and SPER on senescence and CI. Vase life, CI and quality of cut flowers were improved by GABA and SPER treatments. No CI was observed in GABA-treated flowers at 1.5 °C; while, flowers sprayed with water showed severe CI. GABA treatments efficiently prolonged the vase life for 6–7 days more than the control (15 days). GABA and SPER increased the fresh weight, solution uptake, protein and proline contents, catalase, peroxidase, and superoxide dismutase activities, while decreased the electrolyte leakage, H2O2, and malondialdehyde contents, polyphenol oxidase, lipoxygenase, and phospholipase D activities. GABA and SPER significantly prolonged the vase life and prevented degradation of proteins and chilling damage and increased capacity of detoxifying and scavenging of H2O2 and reactive oxygen species (ROS), led to alleviate the negative consequences of the senescence and CI.

Nigella sativa L. (NS) is an herbaceous plant, possessing phytochemicals of therapeutic importance. Thymoquinone is one of the active phytochemicals of NS that confers noteworthy antioxidant properties. Sodium azide, an agent of abiotic stress, can modulates antioxidant system in plants. In the present investigation, sodium azide (0, 5 µM, 10 µM, 20 µM, 50 µM, 100 µM and 200 µM) doses administered to the in vitro NS callus cultures for production/modification of secondary metabolites with augmented activity. 200 µM sodium azide treated NS callus exhibited maximum peroxidase activity (1.286 ± 0.101 nanokatal mg−1 protein) and polyphenol oxidase activity (1.590 ± 0.110 nanokatal mg−1 protein), while 100 µM sodium azide treated NS callus for optimum catalase activity (1.250 ± 0.105 nanokatal mg−1 protein). Further, 200 µM sodium azide treated NS callus obtained significantly the highest phenolics (3.666 ± 0.475 mg g−1 callus fresh weight), 20 µM sodium azide treated NS callus, the highest flavonoids (1.308 ± 0.082 mg g−1 callus fresh weight) and 100 µM sodium azide treated NS callus, the highest carotenes (1.273 ± 0.066 mg g−1 callus fresh weight). However, NS callus exhibited a decrease in thymoquinone yield/content vis-à-vis possible emergence of its analog with 5.3 min retention time and an increase in antioxidant property. Treatment with 200 µM sodium azide registered significantly the lowest percent yield of callus extract (4.6 ± 0.36 mg g−1 callus fresh weight) and thymoquinone yield (16.65 ± 2.52 µg g−1 callus fresh weight) and content (0.36 ± 0.07 mg g−1 callus dry weight) and the highest antioxidant activity (3.873 ± 0.402%), signifying a negative correlation of the former with the latter. DNA damage inhibition (24.3 ± 1.7%) was recorded significantly maximum at 200 µM sodium azide treatment. Sodium azide treated callus also recorded emergence of a new peak at 5.3 min retention time (possibly an analog of thymoquinone with augmented antioxidant activity) whose area exhibits significantly negative correlation with callus extract yield and thymoquinone yield/content and positive correlation with antioxidant activity and in vitro DNA damage inhibition. Thus, sodium azide treatment to NS callus confers possible production of secondary metabolites or thymoquinone analog (s) responsible for elevated antioxidant property and inhibition to DNA damage. The formation of potent antioxidants through sodium azide treatment to NS could be worthy for nutraceutical and pharmaceutical industries.

This study aims to assess and determine the oral-administration of probiotic, Lactobacillus pentosus BD6 on growth performance, immunity and disease resistance of white shrimp, Litopenaeus vannamei. Lac. pentosus BD6 effectively inhibited the growth of aquatic pathogens, which was used in the test. Shrimp were fed with the control diet (without probiotic supplement) for 60 days and the probiotic-containing diets at 107, 108, 109, and 1010 cfu kg−1, respectively. Shrimp fed with the diet containing probiotic at the doses of 109−10 cfu kg−1 showed significant increase in growth performance as well as feed efficiency than that of the control. After a challenge test with Vibrio alginolyticus, shrimp fed with a probiotic diet at a dose of 1010 cfu kg−1 showed a significantly lower mortality as compared to the control and that of shrimp fed the diet containing probiotic at the levels up to 107−8 cfu kg−1. In addition, a therapeutic potential of Lac. pentosus BD6 was discovered because the cumulative mortalities of shrimp fed with probiotic and pathogen V. parahaemolyticus simultaneously were significantly lower when compared to control shrimp. Probiotic in diet at a dose of 109−10 cfu kg−1 significantly increased PO activity of shrimp, while shrimp receiving probiotic at the doses of 108−10 cfu kg−1 showed significant increase in lysozyme activity and phagocytic activity. Shrimp fed with the diet containing probiotic at the level of 1010 cfu kg−1 also indicated higher gene expression of prophenoloxidase (proPO) I, but not proPO II, lipopolysaccharide and β-1,3-glucan-binding protein and penaeidin 4. Analysis of the bacterial microbiota of the shrimp intestine revealed that oral administration of probiotic increased the relative abundance of beneficial bacteria and reduced the abundance of harmful pathogenic bacteria in the gut flora of shrimp. Despite no statistically significant difference, an analysis of microbial diversity recorded higher species richness, Shannon–Weaver diversity index and evenness in the probiotic group, compared to the control group. It was concluded that Lac. pentosus BD6 has great antibacterial ability against a wide range of pathogens and has therapeutic potential to reduce the mortality of shrimp infected with V. parahaemolyticus. Additionally, dietary Lac. pentosus BD6 at the level of 1010 cfu kg−1 was recommended to improve growth performance, immunity and disease resistance of shrimp against V. alginolyticus.

In the present study, we investigated the impacts of ultrasonic conditions on the phytochemical profiles, antioxidant activity, and polyphenol oxidase (PPO) and peroxidase (POD) activities in coffee leaves. Ultrasonic frequency, power, and time, pH, and incubation time affected PPO and POD differently, thus resulting in different ABTS scavenging capacity and phenolic content in coffee leaves. Triple-frequency (20/35/50 kHz) ultrasound significantly (P 0.05) inhibited trigonelline, caffeine, mangiferin, rutin, chlorogenic acids, antioxidant activity, and PPO activity, while the single frequency of 35 kHz increased the phenolics compounds, which was associated with the lowest POD activity. Increasing the incubation time after ultrasonication gradually decreased phenolic compounds and antioxidant activities, however, POD activity followed a temporal pattern of first increase and then decrease. Our results showed that PPO and POD were temporally inactivated after ultrasonication, which leading to the continuous decrease of phenolics in coffee leaves.

This study aimed to investigate the effect of chia seed mucilage (CSM) - bacterial cellulose nano-fiber (CNF) edible coating on bioactive compounds and antioxidant enzyme activity of strawberries. Strawberries were coated with CSM containing 0.6 and 8.0% (w/w) of CNF. The content of total phenol, flavonoids, anthocyanin, ascorbic acid, protein content, antioxidant activity and the activity of polyphenol oxidase, peroxidase, superoxide dismutase and phenylalanine ammonia-lyase enzymes were evaluated. The use of CSM - CNF edible coatings further preserved the phenolic, flavonoid, ascorbic acid and antioxidant activity of strawberries, and this effect was more evident in the CSM-coated sample containing CNF; However, the accumulation of anthocyanins in the coated samples was lower than the control sample. The activity of polyphenol oxidase and peroxidase enzymes, which lead to the degradation of phenolic compounds and brown color in the product, was also effectively controlled by the edible coating.

Coupled dinuclear copper oxygen cores (Cu2 O2 ) featured in type III copper proteins (hemocyanin, tyrosinase, catechol oxidase) are vital for O2 transport and substrate oxidation in many organisms. μ-1,2-cis peroxido dicopper cores (C P) have been proposed as key structures in the early stages of O2 binding in these proteins; their reversible isomerization to other Cu2 O2 cores are directly relevant to enzyme function. Despite the relevance of such species to type III copper proteins and the broader interest in the properties and reactivity of bimetallic C P cores in biological and synthetic systems, the properties and reactivity of C P Cu2 O2 species remain largely unexplored. Herein, we report the reversible interconversion of μ-1,2-trans peroxido (T P) and C P dicopper cores. CaII mediates this process by reversible binding at the Cu2 O2 core, highlighting the unique capability for metal-ion binding events to stabilize novel reactive fragments and control O2 activation in biomimetic systems.

Plants are equipped with a wide range of defensive mechanisms such as morphophysiological, biochemical, molecular, and hormonal signaling for protecting against insect-pest infestation. The infestation of a devastating pest shoot fly [Atherigona soccata (Rodani)] at seedling stage causes huge loss of sorghum crop productivity. In morphophysiological screening ICSV700, ICSV705, and IS18551 have been categorized as resistant, PSC-4 moderately resistant, SL-44 and SWARNA as susceptible. The present study focused on the role of defensive gene expression and its products viz: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), polyphenol oxidase (PPO), phenyl alanine ammonia lyase (PAL), responsive enzymes, and metabolites restoring redox status in sorghum plants against shoot fly infestation. In both leaf and stem tissue of sorghum genotypes, shoot fly infestation induced SOD, APX, DHAR, GR, PAL, and PPO activities while CAT activity was significantly declined at 15 and 21 days after emergence (DAE). IS18551 with resistant behavior showed upregulation of SOD, GR, APX, and DHAR along with accumulation of ascorbate, glutathione enhancing redox status of the plant during shoot fly infestation at later stage of infestation. While SWARNA with susceptible response exhibited enhanced activity of phenylpropanoid pathway enzymes PAL and PPO which in turn increased the levels of secondary metabolites like o-dihydroxyphenol and other phenols deterring the insect to attack the plant. The qRT-PCR data predicted that stress-responsive genes were initially unregulated in SWARNA; however, at 21 DAE, multifold higher expression of SOD, CAT, APX, and PPO (24.8-, 37.2-, 21.7-, and 17.9-fold respectively) in 1S18551 indicates the resistance behavior of this genotype against insect infestation owing to sustainable development capability.

In order to study the effect of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 combined with heat treatment on Monilinia fructicola in peach and Colletotrichum gloeosporioides in litchi fruit, fruits were treated with B. subtilis CF-3 VOCs and hot air alone or in combination. The quality indexes of peach and litchi fruit after treatment and the changes in defense-related enzymes were measured. The results showed that the B. subtilis CF-3 VOCs combined with heat treatment could significantly reduce the rot index of peach and litchi fruit, and effectively maintain firmness and soluble solids content, as well as reduce weight loss of fruits. The combined treatment effectively enhanced the activity of peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT), and superoxide dismutase (SOD) than either treatment alone, and enhanced the resistance of fruit to pathogenic fungi by activating disease-resistant enzymes (phenylalanine ammonia-lyase [PAL], chitinase [CHI], β-1, 3-glucanase [GLU]) activity. In this study, B. subtilis CF-3 VOCs combined with heat treatment maintained the quality and delayed the decline of peach and litchi fruit, providing a theoretical basis for future applications. PRACTICAL APPLICATION: The combination of B. subtilis CF-3 VOCs and heat treatment reduce the extent of M. fructicola and C. gloeosporioides. The combination maintain the quality of peach and litchi better. The combination obviously improve the activity of defense-related enzyme in fruit.

BACKGROUND: Peanut is among the most common of food allergies, and one of its allergens is Ara h 2. A previous study revealed that this allergen was recognized by serum immunoglobulin E (IgE) in over 90% of a peanut‐allergic patient population. Enzymatic cross‐linking is a popular processing method used to tailor food functionality, such as antigenicity. RESULT: The cross‐linking reactions of Ara h 2 were catalyzed by polyphenol oxidase (PPO), and the relevant reaction sites were identified using mass spectrometry and StavroX software. Two pairs of intramolecular cross‐linking peptides and two intermolecular cross‐linking peptides were found. Intramolecular cross‐linking was speculated to occur between ARG¹³¹ (amino acids 116–131) and TYR⁶⁵ (amino acids 63–80) and between TYR⁶⁰ (amino acids 56–62) and ARG⁹² (amino acids 92–102); the intermolecular cross‐linking sites were ARG³¹ with TYR⁸⁴ or TYR⁸⁹ and TYR⁶⁵ or TYR⁷² with ARG⁹² or ARG¹⁰². Three out of four cross‐linking peptides were found in α‐helices, and destruction of this secondary structure resulted in a loose tertiary structure. Although seven linear allergen epitopes were involved in cross‐linking, the IgE binding capacity of protein changed slightly, while its sensitization potential decreased in mouse model. CONCLUSION: Exploring the structural change of Ara h 2 after cross‐linking is beneficial in further understanding the influence of structure on sensitization. This result indicated the future possibility of precision processing on structure of proteins to improve their properties. © 2019 Society of Chemical Industry

Yam tyrosinase has become an economically essential enzyme due to its ease of purification and abundant availability of yam tubers. However, an efficient biochemical and biophysical characterization of yam tyrosinase has not been reported. In the present study, the interaction of yam (Amorphophallus paeoniifolius) tyrosinase was studied with molecules such as crocin (Crocus sativus), hydroquinone, and kojic acid. Surface plasmon resonance (SPR), fluorescence spectroscopy, and circular dichroism techniques were employed to determine the binding affinities and the changes in secondary and tertiary structures of yam tyrosinase in the presence of four relevant small molecules. Hydroquinone and crocin exhibited very low binding affinities of 0.24 M and 0.0017 M. Due to their apparent weak interactions, competition experiments were used to determine more precisely the binding affinities. Structure-function interrelationships can be correlated in great detail by this study, and the results can be compared with other available tyrosinases.

Objective To study the contribution of plant enzyme and microbial activities on protein degradation in silage, this study evaluated the nitrogen transformation dynamics during ensiling of non- and irradiated alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.). Methods Alfalfa and red clover silages were prepared and equally divided into two groups. One group was exposed to γ-irradiation at a recommended dosage (25 Gky). Therefore, four types of silages were produced: i) non-irradiated alfalfa silage; ii) irradiated alfalfa silage; iii) non-irradiated red clover silage; and iv) irradiated red clover silage. These silages were opened for fermentation quality and nitrogen components analyses after 1, 4, 8, and 30 days, respectively. Results The γ-irradiation successfully suppressed microbial activity, indicated by high pH and no apparent increases in fermentation end products in irradiated silages. All nitrogen components, except for peptide-N, increased throughout the ensiling process. Proteolysis less occurred in red clover silages compared with alfalfa silages, indicated by smaller (p

Cashew (Anacardium occidentale L.) is composed of two distinct parts: the nut (fruit), which represents only 10% of the total weight of the harvested product, and the cashew apple (pseudo-fruit), usually known as cashew. This study aimed to determine the hydrocooling temperature of cashew apples and its effects on quality maintenance. Cashews were hydrocooled (HC) by immersion in chlorinated water at 1, 3, 5 and 7 °C. Fruit were cooled in a refrigerator at 5 °C as controls. After treatments, all the fruit were stored at 5 °C for 15 d, and cooling rate, color, freshness, visual assessment, weight loss, and thermal properties were evaluated. Fruit hydrocooled at 1 and 7 °C had lower visual quality and wilting, and greater weight loss, 3 °C was discarded by did not show evident results. A temperature of 5 °C was selected for further studies. Cashew apples were HC at 5 °C, and control treatment cooled in display cold room (CR) at 5 °C, and then fruit from both treatments were stored for 25 days. Samples were taken for physical, physico-chemical and enzymatic analyses at 5 days intervals. HC fruit showed greater freshness, higher firmness and acidity, and slower losses of fresh weight loss and vitamin C when compared with CR. Total phenolic contents decreased during storage, but little effect of treatment on the rate of decline was detected. However, activities of polyphenol oxidase and peroxidase were generally higher in cashew apples with CR than after HC. Red color loss of the cashew apples was constant during storage, regardless of the cooling method. Our study shows that 5 °C is the minimal temperature for hydrocooling of cashew apples, to decrease the risk of damage by cooling, and that this temperature is the optimal temperature for storage of cashew apples

Proline is one of the amino acids that compose proteins and has various roles under non-stress and stress conditions. In this study, we investigated the effect of proline on the growth and browning of two plants, tobacco and rice, by exogenous application and endogenous increase of proline. Exogenous proline had a different effect on the growth and browning between tobacco and rice: proline affected negatively the growth of tobacco seedlings and favorably that of rice seedlings. In addition, proline prevented browning only in rice cultured cells, consistent with the increase of proline contents, but not in tobacco BY-2 cells. These results might be due to the difference of exogenous proline uptake activity in these cells. From the Lineweaver-Burk plots, proline inhibited polyphenol oxidase activity in vitro, which is a major factor of enzymatic browning in plants, by affecting the enzyme-substrate complex. Proline could suppress the browning of the plant callus by inhibition of PPO activity.

Polyphenoloxidase from apple was extracted and further concentrated by cationic reversed micellar extraction. Previous to reversed micellar extraction a crude protein extract was obtained using AG2-X8 as adsorbent of phenolic compounds and the detergent Triton X-100. Forward and backward extraction conditions were optimized by using dodecyl trimethyl ammonium bromide as surfactant in the organic phase. Optimization was carried out to obtain the highest value of PPO activity recovery and the purification fold at the different experimental conditions. Under the optimum extraction conditions, PPO activity recovery was 99% and purification fold reached a value of 17, showing that reversed micellar extraction was a good technique as a first step to concentrate on a targeted enzyme. After removing some impurities by centrifuge ultrafiltration, the protein extract with PPO activity was treated by pressurized carbon dioxide and thermosonication achieving residual PPO activity values of 16 ± 3 and 9 ± 1%, respectively. Quenching experiments by iodide performed in the non-treated extract and in the treated extracts revealed conformational changes of this protein fraction reflected in the greater exposure of the fluorophore to the quencher., Spanish Government (MINECO) and the European Regional Development Fund (ERDF) for financial support of project CTQ2015-64396-R and AEI’s contract, and to Junta de Castilla y León and ERDF for financial support of project BU301P18.

Prophenoloxidase (proPO) is the zymogen form of phenoloxidase (PO), a key enzyme in melanization cascade that has been co-opted in invertebrate immune reactions. There have been reported that proPO plays many essential roles in the crustacean immune system. However, little is known about the function of proPO from red swamp crayfish (Procambarus clarkii) which is an important cultured species worldwide. Here, we cloned and expressed proPO gene from red swamp crayfish (PcproPO). Subsequently, specific antibody against PcproPO was generated. The immune function of PcproPO was further characterized in vitro and in vivo. The results showed that the expression of PcproPO mRNA could be significantly up-regulated during the challenge of Gram-positive-negative (Vibrio parahaemolyticus) and Gram-positive-positive bacterial (Staphylococcus aureus). Furthermore, the purified recombinant PcproPO protein had a strong affinity binding to both bacteria and polysaccharides. In vivo knockdown of PcproPO could significantly reduce the crayfish bacterial clearance ability, resulting in the higher mortality of the crayfish during V. parahaemolyticus infection. In addition, in vitro knockdown of PcproPO in the hemocytes significantly reduced the phenoloxidase (PO) activity and the bacterial clearance ability, indicating that PcproPO might involve in hemocyte-mediated melanization. Our results will shed a new light on the immune function of PcproPO in the crayfish.

Two heteroleptic cobalt(III) complexes, [CoL1(acac)(N3)] (1) and [CoL1(acac)(NCS)] (2) {where HL1 = 1-((2-(dimethylamino)ethylimino)methyl)naphthalen-2-ol and Hacac = acetylacetone} have been synthesized and structurally characterized by several analytical techniques including single crystal X-ray diffraction analysis. Extended supra-molecular assemblies were generated in them through weak noncovalent interactions. Synthesized complexes have also been found to mimic the role of quite a lot of metalloenzymes like catechol oxidase, phenoxazinone synthase and phosphatase efficiently by catalytic areal oxidation of respective substrates. Detailed kinetic studies of catalytic reactions are performed spectrophotometrically, which confirm that catalytic reactions follow Michaelis-Menten enzymatic reaction kinetics. Role of co-ligands in catalytic activity has also been assessed.

The effect of different nitrogen sources (glucosamine sulfate, ammonium sulfate, aspartic acid, phenylalanine and peptone) in comparison to sodium nitrate, the major nitrogen compound in basal agar Czapek’s synthetic medium growth were studied on the linear growth of Rhizoctonia solani and its pathogenicity on faba bean germinated seeds. Ammonium sulfate exhibited faster liner growth and showed the same effect as the basal medium with sodium nitrate while, glucosamine sulfate showed less growth rate compared with sodium nitrate. Glucosamine sulfate and ammonium sulfate showed significant reduction in number of infection cushions which led to significant decrease of disease index in vitro. Our results showed strongly significant positive correlations between disease index and both of diameters of hyphae and number of infection cushions while, very weak correlation coefficient was found between disease index and linear growth of R. solani. Under greenhouse conditions, glucosamine sulfate or peptone as a sole nitrogen sources in food requirements of Rhizoctonia solani inoculum depressed the virulence of the fungus. The effect of different amounts of glucosamine sulfate was determined on fungal growth rate, infection cushions, disease index in vitro and polyphenol oxidase activity. Increasing amount of glucosamine sulfate showed significantly reduction of growth rate in comparison to the basal medium with sodium nitrate. All seeds subjected to R. solani grown on different amount of glucosamine sulfate showed the lower number of infection cushions, disease index and polyphenol oxidase activity compared with sodium nitrate. Under greenhouse conditions, disease index showed significantly decreased effect when glucosamine sulfate used as soil applications and showed better effect on shoot weight and root weight compared with control plants treated with sodium nitrate. Our study proposes that glucosamine sulfate may acts as controlling factor of pathogenicity genes of R. solani. Key words: Rhizoctonia solani, faba bean, Vicia faba, nitrogen sources, glucosamine sulfate, pathogenicity.

Bacterial spot disease caused by Xanthomonas axonopodis pv. vesicatoria is considered one of the major diseases of tomato crop worldwide. The objective of this paper was to study the effect of certain essential oils (EOs), lemongrass, oleum and thyme, on X. axonopodis pv. vesicatoria (PHYX14) for controlling bacterial spot disease in tomato plants. The tested three essential oils (EOs) showed antibacterial activity in vitro test at 1:10 concentration against the PHYX14.Thyme oil exhibited the highest inhibition against PHYX14 followed by lemongrass and finally oleum. Under greenhouse conditions, the effect of EOs on the bacterial spot of tomato was evaluated on tomato seedlings. Thyme oil exhibited the highest reducing of tomato bacterial spot followed oleum and then lemongrass. Results indicated that the application of the tested (EOs) to tomato plants two days after the infection caused the highest reduction of disease severity. While the application of oleum oil exhibited the highest induction of the oxidative enzymes, peroxidase (PO) and polyphenol enzyme (PPO). Also increased total phenolic contents of tomato leaves followed lemongrass and then thyme oil as compared by control. The application of EOs two days before the infection caused the highest induction of PO, PPO enzymes and total phenolic contents in tomato leaves than two days after the inoculation.

The napthyl/pyridine-pyrazole-derived complexes, [Mn(L1)Cl2] (1), [Co(L1)Cl2] (2), [Cu(µ-Cl)(Cl)(L)]2 (3), [Cu2(L)2(N3)3(µ2-N3)] (4), and [Co(L2)Cl2] (5) (where L1 = bis-(3,5-dimethyl-pyrazol-1-ylmethyl)-napthalen-1-ylmethyl-amine (L1), L = 5-methyl-pyrazol-1-ylmethyl) -napthalen-1-ylmethyl-amine (L) and L2 = 2-[2-(3,5-dimethyl-pyrazol-1-yl)-1-methyl-ethyl]-pyridine), exhibited phenoxazinone synthase activity in methanol in the range 5–54 h−1. Binuclear copper(II) derivatives 3 and 4 show better catalytic activities than manganese(II) and cobalt(II) derivatives. The kinetic studies reveal that phenoxazinone chromophore is produced via a complex-substrate intermediate. Further, 3 and 4 show catecholase activity in methanol in the presence of oxygen. All the complexes showed potent antimicrobial activity against the tested strains of bacteria and fungi. Complex 1 was synthesized for the first time by mixing L1 and MnCl2 (1:1) and characterized by single-crystal X-ray crystallography, cyclic voltammetry, density functional theory, and thermogravimetry analysis. The present study suggests that napthyl/pyridyl-anchored pyrazole metal complexes are interesting scaffolds for the development of novel model compounds for biochemical reaction and efficient antimicrobial agents.

Postharvest skin browning of litchi is the major issue which substantially affects its visual quality and market potential. Effect of modified atmosphere packaging (MAP) was studied to manage its surface browning and various quality attributes during storage at 5 ± 1 °C. It was noted that fruits kept under MAP exhibited reduced decay, browning index and loss of fresh weight. MAP storage of fruits markedly suppressed polyphenol oxidase (PPO) activity and delayed production of superoxide anion (O2– ), malondialdehyde (MDA), hydrogen peroxide (H2O2) and relative electrolyte leakage with higher anthocyanin concentrations. Likewise, MAP stored fruits had higher total soluble solids (TSS), ascorbic acid content and titratable acidity (TA) with lower peroxidase (POD) activity. In addition, sensory quality, total phenolic content (TPC), radical scavenging activity, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities were also markedly higher in MAP kept fruits. So, litchi fruits storage under MAP packaging was suitable to delay its postharvest browning and to conserve biochemical attributes and antioxidative enzymes during 28 days cold storage.

Crop domestication and selective breeding have altered plant defense mechanisms, influencing insect-plant interactions. A reduction in plant resistance/tolerance against herbivory is generally expected in domesticated species, however, limited efforts have been made to compare inducibility of plant defenses between wild and domesticated genotypes. In the present study, the inducibility of several plant defense mechanisms (e.g. defensive chemicals, trichomes, plant volatiles) were investigated, and the performance and preference of the herbivore Helicoverpa zea were measured in three different tomato genotypes; a) wild tomato, Solanum pimpinellifolium L. (accession LA 2093), b) cherry tomato, S. lycopersicum L. var. cerasiforme (accession Matts Wild Cherry), and c) cultivated tomato, S. lycopersicum L. var. Better Boy). Enhanced inducibility of defensive chemicals, trichomes, and plant volatiles in the cultivated tomato, and a higher level of constitutive plant resistance against herbivory in the wild genotype was observed. When comparing the responses of damaged vs. undamaged leaves, the percent reduction in larval growth was higher on damaged leaves from cultivated tomato, suggesting a higher induced resistance compared to other two genotypes. While all tomato genotypes exhibited increased volatile organic compound (VOCs) emissions in response to herbivory, the cultivated variety responded with generally higher levels of VOCs. Differences in VOC patterns may have influenced the ovipositional preferences, as H. zea female moths significantly preferred laying eggs on the cultivated versus the wild tomato genotypes. Selection of traits during domestication and selective breeding could alter allocation of resources, where plants selected for higher yield performance would allocate resources to defense only when attacked.

The performance of calcium nanoparticles (CaNPs) blending in ascorbic acid (AA) to alleviate internal browning symptoms of ‘Hindi Be-Sennara’ mango fruit under cold storage otherwise the impacts of CaNPs-AA on browning enzyme activities such as polyphenol oxidase (PPO, EC: 1.14.18.1) and Phenylalanine ammonia-lyase (PAL, EC: 4.3.1.24) were assessed. The mango fruits were immersed with CaNPs with AA at the diff ;erent concentration (0, 6, and 9 mM) and stored at low temperature (6 °C and 95% RH) for 35 days. Fruit samples were picked every five days interval. The visual measurement of internal browning index (IB-index) was monitored. The chemical analysis, for instance, the total phenol (TP), and flavonoids (FL) content were measured. Moreover, the cell wall degradation enzymes for example lipoxygenase (LOX; EC: 1.13.11), pectinase (PT; EC: 3.2.1.15), cellulase (CEL; EC: 3.2.1.4), and cell membrane leakage percentage were measured. However, the cell wall termination compounds such as lipid peroxidation (malondialdehyde, MDA), and DPPH radical were determined. The CaNPs-AA 9 mM reduced significantly the IB incidence, maintained the phenolic compounds content by preserving cell wall structure and minimizing action of both PPO and PAL activities during cold storage. Moreover, the changes in cell wall degradation enzyme activities were inhibited by CaNPs-AA 9 mM treatment so less leakage percentage. In the same trend, the lowest accumulation of MDA and the highest concentration of DPPH was monitored too. As the main conclusion, using the CaNPs-AA 9 mM treatment for 24 h to fruit exhibited significantly a reduction of internal browning incidences of mango during cold storage.

Ternary copper(II) complexes with the molecular formulae of [CuIILL′]X or [CuIILL′X]; L = l -Valinate; L′ = α, ά-bipyridyl or 1,10 - phenanthroline and X is Cl¯, Br¯, NO3¯, AcO¯, ½SO42− or ClO4¯ were synthesized. Elemental and thermal analysis in addition to electrochemical (molar conductance and cyclic voltammetry), magnetic moment measurements as well spectral (FT-IR, UV–Vis and ESR) techniques were used to characterize the complexes. The spectroscopic results suggested square pyramidal and square planar geometries for the five- and four-coordinate complexes respectively. Powder X-ray diffraction spectral data along with the structure solution program Expo 2014 has been used for structural elucidation of the sulfato complexes 1 and 5. Stopped follow technique was employed to study the substitution of the nonelectrolytic coordinately counter anion ligand by using thiourea (TU) as a function of nucleophile and a biphasic process is proposed. An initial fast reaction is followed by a slower one and the initial one was found to be counter ion dependent. Bio-mimicking the multicopper oxidase enzyme such as catechol oxidase and phenoxazinone synthase is a further goal of the present study. Catalytic examinations displayed that the present complexes are promising candidates as functional mimic of the examined enzymes and the probable mechanistic catalytic sequences are discussed.

Litchi (Litchi chinensis Sonn. cv. ‘Feizixiao’) has a high market value. However, its value declines during postharvest storage because its quality deteriorates, and its pericarp turns brown. Therefore, safe and effective ways of improving litchi quality and inhibiting postharvest browning are required. In this study, 5-aminolaevulinic acid (5-ALA) and thidiazuron (TDZ) were applied to litchi fruit before harvest to determine their relative effects on litchi colour and postharvest storage characteristics. The results showed that preharvest 5-ALA application significantly increased postharvest fruit weight, anthocyanins, total phenol, vitamin C and antioxidant activity relative to those in the untreated fruits. Compared with the control, TDZ significantly increased fruit weight but inhibited anthocyanin accumulation and did not significantly alter antioxidant activity. Both preharvest treatments significantly reduced the browning index, the relative leakage rate and polyphenol oxidase activity after 6 d of storage. A membership function analysis indicated that preharvest 5-ALA application was the most beneficial for postharvest storage whereas TDZ treatment was relatively less effective. Preharvest colour promotion was preferable for improving litchi quality and inhibiting postharvest browning.

Ectropis obliqua Prout is the main pest of the tea plant Camellia sinensis (L.) O. Kuntze in China, affecting an annual area of more than one million acres. (−)-Epigallocatechin-3-gallate (EGCG) is the major catechin in tea leaves. Here, we show that EGCG is highly efficient in increasing the survival rate of E. obliqua larvae. We also compared the gut peroxidase (PO) activity between EGCG-fed and control larvae. EGCG-fed larvae had significantly greater PO activity levels than control larvae. Western blotting validated these results. Gut PO activity levels of larvae fed an artificial diet gradually decreased and disappeared completely by day 5. We hypothesize that the increased survival rate of EGCG-fed larvae was associated with increased PO activity. This research provides evidence that E. obliqua larvae have adapted to, and may even benefit from, secondary compounds found in tea leaves.

The blue mold caused by Penicillium italicum in grapefruit fruit was controlled by the antifungal activities of Carboxymethyl chitosan (CMCS) alone and combined with Cryptococcus laurentii treatments in this study. According to the study results spore germination of P. italicum can be inhibited by both CMSC and C. laurentii treatment. Moreover, the growth of C. laurentii can be maintained by low CMCS concentration in vitro. The blue mold in grapefruit fruit inoculated with P. italicum was decreased in all treatments compared with the control fruit. The combination of CMSC and C. laurentii treatment resulted in a significantly synergistic effects in smallest lesion diameter and decay incidence. The defense enzyme activities, such as phenylalanine ammonia-lyase, polyphenol oxidase, peroxidase and antifungal compounds like total phenolic related to disease resistance can be induced by combined treatment. Furthermore, the commercial quality parameters of the CMCS combined with C. laurentii treatment which were measured by ascorbic acid, titratable acidity, weight loss and total soluble solid, were better than those treated with treatments alone. According to the results, the combination of CMSC and C. laurentii treatment can maintain fruit quality and control postharvest decay more effectively than single treatment, and can be commercially used in grapefruit fruit.

Macadamia nut is rich in monounsaturated fatty acids, which are known to reduce the risk of cardiovascular diseases when included as part of a healthy human diet. On the negative side, high concentrations of unsaturated fatty acids lead to oxidative reactions, which result in rancidity thus decreases the quality of the nut. Drying and roasting are, therefore, needed to reduce moisture content and hence alleviate the above-mentioned problems. This research was conducted to evaluate and compare the quality properties of raw and roasted macadamia nuts during the accelerated storage of 70 days. Two commercially important macadamia cultivars, namely, ‘A4’ and ‘Beaumont’ were used as model cultivars. Nuts were roasted at 125 °C for 15 min using a hot air oven dryer. Roasted kernels of ‘A4’ and ‘Beaumont’ cultivars had significantly lower concentration of peroxide value (PV), high concentration of flavonoids, phenols and antioxidants activity and good sensory quality compared to raw kernels which had a higher concentration of polyphenol oxidase activity, PV, low concentration of flavonoids, phenols and antioxidant activity and poor sensory quality during the accelerated storage of 70 days. These results indicated that roasting significantly improved kernel quality and shelf life of ‘A4’ and ‘Beaumont’ macadamia cultivars.

Fusarium wilt disease, caused by Fusarium oxysporum f. sp. cubense, especially by tropical race 4 (Foc TR4), is threatening the global banana industry. Musa acuminata Pahang, a wild diploid banana that displays strong resistance to Foc TR4, holds great potential to understand the underlying resistance mechanisms. Microscopic examination reports that, in a wounding inoculation system, the Foc TR4 infection processes in roots of Pahang (resistant) and a triploid cultivar Brazilian (susceptible) were similar by 7 days post inoculation (dpi), but significant differences were observed in corms of both genotypes at 14 dpi. We compare transcriptomic responses in the corms of Pahang and Brazilian, and show that Pahang exhibited constitutive defense responses before Foc TR4 infection and inducible defense responses prior to Brazilian at the initial Foc TR4 infection stage. Most key enzymatic genes in the phenylalanine metabolism pathway were up-regulated in Brazilian, suggesting that lignin and phytotoxin may be triggered during later stages of Foc TR4 infection. This study unravels a few potential resistance candidate genes whose expression patterns were assessed by RT-qPCR assay and improves our understanding the defense mechanisms of Pahang response to Foc TR4.