Search

The marine and freshwater Hildenbrandia samples were collected from diverse locations of China and Japan, and morphological characterization and molecular phylogenetic analysis were conducted on these samples. Morphological measurements of freshwater specimens were consistent with the results of H. jigongshanensis, whereas cell dimensions of marine specimens were slightly larger than those of widely distributed H. rubra and H. crouanii. Phylogenetic trees based on rbcL, psbA and UPA sequences were consistent. Freshwater specimens collected in this study formed an independent clade with H. jigongshanensis supported by high values. Species attribution was confirmed further by the similar ITS2 secondary structures among the samples of H. jigongshanensis. It was found that the intraspecific divergence of rbcL gene in H. jigongshanensis was smaller than other two freshwater species H. rivularis and H. angolensis. Phylogenetic trees showed that marine specimens in this study grouped together with H. rubra samples of North America, and were different with the H. rubra samples of Europe. Combining the comparison results of CBC numbers in ITS2 secondary structure, we propose the marine samples collected in this study to be a new species Hildenbrandia qingdaoensis sp. nov. The separation of the marine and freshwater specimens was supported by the rbcL, UPA and psbA phylogeny as well as ITS2 secondary structure inference. Biogeographical reconstruction showed the ancestor of freshwater Hildenbrandia might derive from South America and dispersed from North America to Europe and then to Asian countries, which needs to be verified further with more samples and molecular evidences from South America. [ABSTRACT FROM AUTHOR]

Land‐use change has significant influences on soil respiration (Rs) in terrestrial ecosystems. Soil microbes play critical roles in soil carbon cycling. Nevertheless, the specific mechanism of how changes in soil microbial properties are linked to the variation of Rs rate during land‐use change still remains poorly understood, especially in the Loess Plateau, China. Here, the characteristics of Rs rate and soil microbial community following the land‐use change from farmland to plantation/grassland were analyzed via an automated soil CO2 flux system and high‐throughput 16S rDNA gene sequencing. The afforestation altered soil microbial diversity and community composition, which was mainly explained by soil pH, temperature, organic matter, nitrate, alkali‐hydrolyzed nitrogen, and available phosphorus. The biomarkers of Bacteroidetes, Firmicutes, and Thaumarchaeota were found in farmland soil at the phylum level. The afforestation also significantly decreased Rs rate, which was closely related to Shannon's index, Simpson's index, and some microbial taxa, such as Bacteroidetes, Firmicutes, Nitrospirae, and Acidobacteria. Bacteroidetes, and Firmicutes were particularly expected to be important drivers of high Rs rate in farmland soil. Moreover, the microbial interaction was probably also an important factor affecting Rs rate. Our results indicate that the response of Rs to land‐use change depends on soil microbial community being regulated by soil physicochemical properties in the Loess Plateau, China. [ABSTRACT FROM AUTHOR]

Salt stress is one of the abiotic stress factors that affect the normal growth and development of higher plants and algae. However, few research studies have focused on calcium stress, especially in algae. In this study, the mechanism of tolerance to high calcium stress of a Parachlorella kessleri strain was explored by the method of transcriptomics combined with physiological and morphological analysis. Concentrations of CaCl2 100 times (3.6 g/L) and 1000 times (36 g/L) greater than the standard culture were set up as stresses. The results revealed the algae could cope with high calcium stress mainly by strengthening photosynthesis, regulating osmotic pressure, and inducing antioxidant defense. Under the stress of 3.6 g/L CaCl2, the algae grew well with normal cell morphology. Although the chlorophyll content was significantly reduced, the photosynthetic efficiency was well maintained by up-regulating the expression of some photosynthesis-related genes. The cells reduced oxidative damage by inducing superoxide dismutase (SOD) activities and selenoprotein synthesis. A large number of free amino acids were produced to regulate the osmotic potential. When in higher CaCl2 stress of 36 g/L, the growth and chlorophyll content of algae were significantly inhibited. However, the algae still slowly grew and maintained the same photosynthetic efficiency, which resulted from significant up-regulation of massive photosynthesis genes. Antioxidant enzymes and glycerol were found to resist oxidative damage and osmotic stress, respectively. This study supplied algal research on CaCl2 stress and provided supporting data for further explaining the mechanism of plant salt tolerance. [ABSTRACT FROM AUTHOR]

Batrachospermaceae is the largest family of freshwater red algae, widely distributed around the world, and plays an important role in maintaining the balance of spring and creek ecosystems. The deterioration of the current global ecological environment has also destroyed the habitat of Batrachospermaceae. The research on the environmental factors of Batrachospermaceae and the accurate classification of the genus is necessary for the protection, restoration, excavation, and utilization of Batrachospermaceae resources. In this paper, the database of geographical distribution and environmental factors of Batrachospermaceae was sorted out, and the relationship between the classification of genus and environmental factors in Batrachospermaceae was analyzed based on two machine learning methods, random forest and XGBoost. The result shows: (1) The models constructed by the two machine learning methods can effectively distinguish the genus of Batrachospermaceae based on environmental factors; (2) The overall AUC score of the random forest model for the classification and prediction of the genus of Batrachospermaceae reached 90.41%, and the overall AUC score of the taxonomic prediction of each genus of Batrachospermaceae reached 85.85%; (3) Combining the two methods, it is believed that the environmental factors that affect the distinction of the genus of Batrachospermaceae are mainly altitude, average relative humidity, average temperature, and minimum temperature, among which altitude has the greatest influence. The results can further clarify the taxonomy of the genus in Batrachospermaceae and enrich the research on the differences in environmental factors of Batrachospermaceae. [ABSTRACT FROM AUTHOR]

Three species of the genus Synura from China are described here. Morphological observations and molecular phylogenetic analyses were conducted for three specimens collected at different locations in China. The described morphological features included cell size, scale size, spines, keels, and struts. Molecular analyses based on multiple genetic markers (SSU and LSU rDNA and internal transcribed spacer rDNA) were used to determine the phylogenetic positions of the three Synura species. Morphologically, specimen GZ201017 collected in Guizhou Province was characterized by a well-developed keel and lanceolate scales; specimen SX210304 collected in Shanxi Province was characterized by a less-developed keel and poor silicification; and specimen GD201126 collected in Guangdong Province was characterized mainly by spines with blunt ends or two small teeth on the tips. The morphotypes GZ201017, SX210304, and GD201126 corresponded to the original descriptions of Synura petersenii, S. glabra, and S. longitubularis, respectively. This discovery laid a foundation for the molecular phylogeny of the genus Synura and an enhanced understanding of Synura diversity and distribution in China. [ABSTRACT FROM AUTHOR]

Mercuric chloride (HgCl2) is a common heavy-metal pollutant widely used in commercial products and industry, but its excessive use and uncontrolled discharge have caused great harm to aquatic environments and human health. To research the mechanisms of HgCl2 toxicity in aquatic organisms, this study cultured the green alga Scenedesmus quadricauda in a gradient of HgCl2 concentrations (0, 0.1, 0.3, 0.5, 0.7, and 0.9 mg/L) for 9 days. The results showed that: (1) when the concentrations of HgCl2 were high (≥0.7 mg/L), the toxic effects completely inhibited the growth of algal cells, the culture liquid changed from green to light yellow, and cells aggregated and sank to the bottom. Submicroscopic structural imaging showed that at 0.9 mg/L HgCl2, the algal cells were seriously damaged and obvious plasma–wall separation occurred. Furthermore, the arrangement of photosynthetic lamellae became disordered and the nuclei and protein nuclei faded or even disappeared. (2) When the concentrations of HgCl2 were low and medium (≤0.5 mg/L), the activity of superoxide dismutase (SOD) in algal cells increased in the first five days, but the degree of increase was smaller than in the control group. However, under high HgCl2 concentrations (≥0.7 mg/L), the activity of SOD began to decrease sharply on the seventh day. The activity of peroxidase (POD) decreased more obviously than that of SOD. (3) Under medium and high HgCl2 concentrations (≥0.5 mg/L), the content of malondialdehyde (MDA) in algal cells increased over time, and had not decreased again by the last day of measurement. In contrast, the contents of total protein (TP) and soluble sugar (SS) both exhibited decreasing trends under high HgCl2 concentrations. (4) When the HgCl2 concentrations were ≥0.7 mg/L, the content of photosynthetic pigments in algal cells decreased, and the light quantum yield of PS Ⅱ decreased. At the same time, as culture time progressed, the photosynthetic electron transfer and energy-conversion efficiency were seriously damaged and photosynthesis never returned to normal levels. This research provides a reference for understanding the mechanism by which HgCl2 pollution affects aquatic ecosystems and may help with pollution management in the future. [ABSTRACT FROM AUTHOR]

A new species of freshwater alga, Chara zhengzhouensis, is described and illustrated based on material collected in a lake at Zhengzhou, in Henan Province, China. Phylogenetic analysis of sequence data from the 18s rDNA, rbcL, and atpB indicated the separation between C. zhengzhouensis and other species of the genus Chara. Additionally, from a morphological point of view, C. zhengzhouensis differs from another closely related species, C. connivens, in its diplostichous cortex and corticate or ecorticate in based segments of branchlets. Therefore, the results based on both morphological observation and molecular evidence facilitated the proposal of this new species—C. zhengzhouensis. It represents another species in the charophyte diversity in China and the description of this new species provides more molecular data for phylogenetic analysis of the genus Chara. [ABSTRACT FROM AUTHOR]

Chlorophyll a concentration is an important indicator to characterize phytoplankton biomass, which further reflects the water quality of lakes. Based on the data of chlorophyll a concentration and environmental factors extracted from the ChlaData, HydroLAKES, and HELLAKES databases for Chinese lakes for three years (2000, 2005, and 2010), we used the random forest model and the generalized linear model to analyze the relationship between chlorophyll a concentration and environmental factors in Chinese lakes and predict the chlorophyll a concentration. The results showed that the relative importance of environmental factors for chlorophyll a was as follows: nutrient salt concentration > longitude and latitude > monthly mean precipitation > altitude > annual average temperature. The coefficient of determination of the random forest model was 0.9997 (R2 = 0.9997), and the root-mean-square error was 0.0010 (RMSE = 0.0010), with high prediction accuracy. The random forest model and the generalized linear model both showed that TP was the main influencing factor of chlorophyll a concentration. The validation results based on the measured data show that the models are reliable. By making more accurate predictions of chlorophyll a concentrations, we can facilitate the prevention, control, and treatment of lake blooms. [ABSTRACT FROM AUTHOR]

In order to explore the characteristics of the periphytic algae community structure and its relationship with environmental factors in the Taiyuan region of the Fenhe River, a total of six sampling sites were investigated in July and December 2021. The effects of water quality status and environmental factors at each sampling point on the community structure of epiphytes were detected. The results showed that a total of 7 phyla and 54 genera of periphytic algae were identified in the Taiyuan region of the Fenhe River, and the species composition was mainly Bacillariophyta, Cyanophyta, and Chlorophyta. According to the analysis results of the biodiversity index, the water body of the Taiyuan region of the Fenhe River is in a state of moderate pollution. The correlation analysis between the epiphytic algae and environmental factors showed that the cell density of algae was significantly correlated with dissolved oxygen (DO), phosphate ( PO 4 3 − -P), chemical oxygen demand (COD), total phosphorus (TP), and transparency (SD) in the wet season. The algal cell density in the dry season was significantly correlated with water temperature (WT), TP, PO 4 3 − -P, and COD. According to the redundancy analysis, the community distribution of the epiphytic algae in the Taiyuan region of the Fenhe River was closely related to physical and chemical factors such as COD, nitrate nitrogen ( NO − 3   -N), WT, dissolved organic carbon (DOC), total nitrogen (TN), and TP, and COD is the main environmental factor driving the change in the community distribution of the periphytic algae in the wet season. TN is the main control factor driving the change in the biological community distribution of periphytic algae in the dry season. [ABSTRACT FROM AUTHOR]

The genus Lemanea is an evolutionally derived lineage of freshwater Rhodophyta which has a rare distribution. Morphological characterization and molecular phylogenetic analyses were conducted for a Lemanea specimen collected from Guilin, China, in this study. The results based on morphological observation and molecular evidence, including rbcL and SSU sequences, showed it was a new record of L. manipurensis Ganesan, West, Zuccarello et Rout in China. The specimen in this study was morphologically characterized by branches that were positioned in the lower part of the thallus, hair cells absent around the outer cortex, ellipsoidal and single carpospores at the top of the gonimoblast filaments and spermatangia formed in continuous wide rings on the thallus nodes. By comparing the morphology of specimens collected from Guilin, China, and the holotype specimen in India, it was found that the spermatangial shapes were variable among different populations. It was found that the presence or absence of hair cells around the outer cortex was not a reliable characteristic for the identification of the genus Lemanea based on a comparison between L. manipurensis collected in Guangxi and in India and another four Lemanea species previously recorded in China. The results of this study provided molecular evidence and a theoretical basis for molecular phylogenetic research on the genus Lemanea and enriched the species diversity and geographical distribution of Lemanea in China. [ABSTRACT FROM AUTHOR]

Eukaryotic microalgae are widespread in soil. They are generally considered to participate in soil development and the formation of the soil food chain. Interestingly, some microalgae can grow in heterotrophic mode. Therefore, it is a reasonable speculation that eukaryotic microalgae may participate in the process of soil respiration (Rs) via the heterotrophic metabolism of soil organic matter. Nevertheless, the mechanism is not well understood. Here, we investigated the eukaryotic microalgal community in farmland and plantation/grassland soil via high‐throughput sequencing focusing on the Loess Plateau, China. Chlorophyta, Chrysophyta, Cryptophyta, Bacillariophyta, Dinophyta, Xanthophyta, and Haptophyta were found in all samples. Nevertheless, the biomarker for farmland soil was affiliated to Chlorophyta and Xanthophyta, whereas the biomarker for plantation/grassland soil was affiliated to Chrysophyta. Moreover, the distribution of soil microalgae was strongly dependent on soil pH, organic matter, and nitrogen. In addition, afforestation significantly decreased Rs rate, which was significantly related to the soil microalgal community, especially 11 taxa of eukaryotic microalgae affiliating to Chlorophyta and Chrysophyta. Meanwhile, the interaction between microalgae and bacteria in farmland soil was stronger than that in plantation/grassland soil, which was also likely to affect Rs rate. These results suggest that beyond plants, soil eukaryotic microalgae are functionally significant but rarely considered participants of Rs. Therefore, they should be considered when investigating soil carbon cycling. [ABSTRACT FROM AUTHOR]

Background: Salinity is an essential abiotic stress in plants. Dunaliella is a genus of high-salt-tolerant microalgae. The present study aimed to compare the characterizations of D. bioculata and D. quartolecta at different levels and investigate novel genes response to salt stress. Methods and results: High chlorophyll contents were detected in D. bioculata on the 35th d of salt stress, while high lipid and carotenoid contents were detected in D. quartolecta via morphological and biochemical analyses. Physiological analysis showed that D. quartolecta cells had a smaller increase in osmotic potential, a smaller decrease in the Na+/K+ ratio and photochemical efficiency (Fv/Fm), and a lower relative conductivity than D. bioculata cells. The genomic lengths of D. quartolecta and D. bioculata were 396,013,629 bp (scaffold N50 = 1954 bp) and 427,667,563 bp (scaffold N50 = 3093 bp) via high-throughput sequencing and de novo assembly, respectively. Altogether, 25,751 and 26,620 genes were predicted in their genomes by annotation analysis with various biodatabases. The D. bioculata genome showed more segmental duplication events via collinearity analysis. More single nucleotide polymorphisms and insertion-deletion variants were detected in the D. bioculata genome. Both algae, which showed a close phylogenetic relationship, may undergo positive selection via bioinformatics analysis. A total of 382 and 85 novel genes were screened in D. bioculata and D. quartolecta, with 138 and 51 enriched KEGG pathways, respectively. Unlike the novel genes adh1, hprA and serA, the relative expression of livF and phbB in D. bioculata was markedly downregulated as salinity increased, as determined by qPCR analysis. The relative expression of leuB, asd, pstC and proA in D. quartolecta was markedly upregulated with the same salinity increase. Conclusion: Dunaliella quartolecta is more halophilic than D. bioculata, with more effective responses to high salt stress based on the multiphase comparative data. [ABSTRACT FROM AUTHOR]

Members of coccoid green algae have been documented in various extreme environments. In this article, a unicellular green alga was found to slowly grow in high concentration (3.6 g/L) and pure calcium chloride solution in the laboratory. It was successfully cultured and a taxonomic study combined approaches of morphological and molecular methods was conducted to determine its classification attribution, which was followed by a preliminary physiology research to explore its unique tolerance characteristics against calcium chloride stress. The strain was identified as Parachlorella kessleri by very similar morphology and the same phylogenetic position. The morphological differences among the three species in genus Parachlorella were then discussed and the characteristic traits of absent or thin mucilaginous envelop and mantel‐shaped chloroplast for P. kessleri were supported. In addition, the almost strictly spherical shape of adult cells could further distinguish the P. kessleri from the other two species. The tolerant characteristics to CaCl2 stress for this strain were confirmed and the limit concentration was revealed as between 2000 and 4000 times than the standard BG11 culture concentration. Therefore, this P. kessleri strain is expected to be a good material to explore the mechanism of resistance to calcium ions stress for eukaryotic microbiology. [ABSTRACT FROM AUTHOR]

The seasonal and spatial eukaryotic phytoplankton composition in the Fenhe River was investigated based on the 18S rDNA V4 region. The relationship between phytoplankton functional groups and environmental factors was explored to effectively capture the responses of these taxa to environmental gradients and their effects on ecosystem function. Our results indicated that the Chlorophyta and Bacillariophyta had higher relative abundance than other taxa, and their diversity and richness indices in spring were higher than those in other seasons. The linear discriminant analysis effect size (LEfSe) analyses detected that the potential seasonal biomarkers included Desmodesmus, Cyclotella, Pseudoschroederia, Discostella, Scenedesmus, Monoraphidium, and Nannochloropsis; the spatial biomarkers included Amphora, Neochloris, Hindakia, Pseudomuriella, Coccomyxa, Chloroidium, Scherffelia, Chromochloris, and Scotinosphaera. The systemic evolution and distribution characteristics of the first 50 representative sequences showed that the dominant genus included Desmodesmus in spring, Pseudopediastrum in summer, Mychonastes in autumn, and Monoraphidium in winter. Main seasonal variation of phytoplankton functional groups was as follows: spring (J + F + C + X1) → summer (J + F + X1 + X2) → autumn (J + F + X1 + C) → winter (X1 + J + B + X2). Pearson correlation, redundancy analysis, and variance partitioning analysis showed temperature and phosphate were the determining factors causing the changes of phytoplankton functional groups and community composition in the Fenhe River. [ABSTRACT FROM AUTHOR]

To research the adaptive evolution and coevolution of the rbcL gene in the genus Galdieria, 36 sequences were selected. The bioinformatics of proteins encoded by rbcL genes of Galdieria were analyzed, and phylogenetic trees were constructed by the maximum‐likelihood method. Then, adaptive evolution and coevolution were analyzed. The phylogenetic tree showed that the inner groups were clustered into four branches, in which the sequences of Galdieria maxima were divided into two small branches, and the posterior probability of each branch is above 94.9%. Eleven reliable positive selection sites were detected in the branched‐site model, indicating that the rbcL protein‐coding gene of Galdieria underwent adaptive evolution to adapt to extreme environments. Site 269 F is located in the loop 6 domain, while sites 272 D and 273 W are located in the 6‐helix structure. Many coevolution pairs were detected, which were closely related to the hydrophobic and molecular weight correlation values of amino acids. The results are helpful to research the evolution process of freshwater red algae, to explore the changes of its essential genes and protein functions to adapt to different environmental pressures, and to understand the close relationship between amino acids in proteins and the molecular mechanism of evolution. [ABSTRACT FROM AUTHOR]

Active films from chitosan incorporated with Arthrospira platensis polysaccharide (APP) of various ratios (0.0%, 0.5%, and 1.0%, w/v) were developed by solution casting. The effect of APP on the structural, physicochemical, mechanical, antimicrobial, and antioxidant properties of the chitosan‐APP films (CA‐film) was investigated. Fourier transform infrared spectra (FTIR) confirmed successful incorporation of chitosan and APP. The compact structure of the films was observed clearly in scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. X‐ray diffraction (XRD) patterns suggest the semi‐crystalline structure was increased upon addition of APP. The composite films showed an improved water resistance and vapor barrier properties, and reduced by at least 27.4% and 32.1% in swelling degree (Sd) and water vapor permeability (WVP) compared with chitosan film (C‐film), respectively. However, the transparency decreased slightly, which may be due to the shrinkage of the spacing of the polymer interchain. The composite films also displayed enhanced the mechanical properties. The antimicrobial activity of the CA‐film showed an increase of at least of 0.41‐fold in inhibition zone diameter for E. coli. At a concentration of 1.2 mg/mL, the antioxidant activity of CA‐film was enhanced by more than threefold compared with C‐film. Therefore, CA‐films have good potential as sources of active packaging material for the food industry. [ABSTRACT FROM AUTHOR]

Green euglenophytes are a group of eukaryotes with ancient origin. In order to understand the evolution of the group, it is interesting to know which characteristics are more primitive. Here, a phylogenetic tree of green euglenophytes based on the 18S rRNA gene was constructed, and ancestral states were reconstructed based on eight morphological characters. This research clarifies the phylogenetic relationships of green euglenophytes and provides a basis for the study of the origin of these plants. The phylogenetic tree, which was constructed by Bayesian inference, revealed that: Eutreptia and Eutreptiella were sister groups and that Lepocinclis, Phacus, and Discoplastis were close relatives; Euglena, Cryptoglena, Monomorphina, and Colacium were closely related in addition to Trachelomonas and Strombomonas; and Euglena was not monophyletic. An ancestral reconstruction based on morphological characters revealed seven primitive character states: ductile surface, spirally striated, slightly narrowing or sharp elongated cauda, absence of a lorica, chloroplast lamellar, shield or large discoid, pyrenoid with sheath, and with many small paramylon grains. However, the ancestral state of the length of the flagellum could not be inferred. Euglena and Euglenaria, which both possessed all of the ancestral character states, might represent the most ancient lineages of green euglenophytes. [ABSTRACT FROM AUTHOR]

Large-scale, inter-basin water diversion projects have been developed to relieve water scarcity crisis and water pollution problems. Environmental status and ecosystem impacts are largely unknown for the Wanjiazhai Yellow River Diversion Project (YRDP-WJZ), a water body critical in northern China. In the current study, twelve hydrochemical indices (including Mn, Cu, Zn, Hg, Pb, NH3-N, COD-Mn, DO, BOD5, COD, TP, and TN) were collected from 2008 to 2017 based on multiple analytical approaches to understand environmental status and ecological risks. Human health risk and threats to aquatic organisms from heavy metals were assessed. Heavy metals have no regular spatial distribution. Biochemical parameters and nutrients pollute seriously in midstream and downstream, respectively. Hydrochemical indices suggested high levels of pollution in the midstream section. Water quality improved downstream of the Fenhe Reservoir, but total nitrogen and total phosphorus in the downstream section increased in recent years. The Canadian Council of Ministers of the Environment Water Quality Index (CWQI) suggested midstream water quality was poor in general, and 80% of annual calculations had a marginal grade. For aquatic organisms, ecological risks of Cu and Zn were high. For local residents, drinking water was generally safe, but continued monitoring is critical due to ongoing threats to water quality in these areas. [ABSTRACT FROM AUTHOR]

Background: Isoniazid (INH) and rifampicin (RFP) are first-line antituberculosis drugs; however, one of the most common adverse effects of their use is hepatotoxicity. Sagittaria sagittifolia polysaccharide (SSP) is the primary component of S. sagittifolia. Our previous research has confirmed the protective effect of SSP against INH and RFP-induced hepatic injury in in vivo model system. Objectives: In this study, we aimed to investigate the protective effect and the underlying mechanisms of SSP in cultured HepG2 cells after induction with INH and RFP. Materials and Methods: The study was designed as follows: normal (without any treatment), model (injury induced by INH + RFP), and SSP group (treated with SSP followed by INH + RFP). Cell viability, catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH), along with malondialdehyde (MDA), as well as alanine aminotransferase, aspartate transaminase, and lactate dehydrogenase, were assessed by corresponding kits. Real-time polymerase chain reaction and Western blot were used to evaluate the mRNA and protein expression of Bcl-2, Bax, Nrf2, and Keap1. Results: SSP had a potential protective effect as it increased the cell viability and reduced the intracellular levels of hepatic injury markers. SSP reduced the intracellular content of MDA and increased the activity of SOD, CAT, and GSH. It is noteworthy that the optimum protective effect was observed with a 0.5 mg/mL SSP at 24 h after treatment. In addition, the protection appears to be associated with its activation of nuclear factor E2-related factor 2 signaling pathway. Conclusion: SSP protected against INH + RFP-induced hepatotoxicity in HepG2 cells and this protection might via Nrf2 signaling pathway. [ABSTRACT FROM AUTHOR]

The robust Taguchi method was used to optimize the preparation of activated carbon by microwave radiation from the agricultural waste Phragmites australis. The potential for removing endocrine disrupting compounds such as bisphenol A from aqueous solutions was explored. Results obtained by using Taguchi orthogonal design indicated that the optimal conditions for P. australis activated carbon, as determined based on the signal-to-noise ratio, were as follows: radiation power, 600 W; radiation time, 20 min; impregnation ratio, 1:1; impregnation time, 24 h; and mass fraction, 70% H3PO4. The heterogeneous surface structural morphology and multifarious functional groups of P. australis activated carbon were characterized by scanning electron microscopy, the Brunauer–Emmett–Teller method, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. In addition, the adsorption kinetic and isotherm experimental data of bisphenol A on P. australis activated carbon could be well fitted with pseudo-second-order kinetic (R2 = 0.9966–0.9991) and Freundlich isotherm (R2 = 0.9939–0.9982) models, respectively. The maximum adsorption capacity of P. australis activated carbon was 181.82 mg/g at 20°C. On the basis of the characterization and model analyses, the adsorption mechanism of bisphenol A on P. australis activated carbon may contribute to H-bonding, hydrophobic effects, and π–π interaction. [ABSTRACT FROM AUTHOR]

The phytoplankton (internal driving forces) and environmental variables that affect complex biochemical reactions (external driving forces) play an important role in regulating photosynthetic carbon fixation. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) exists in various phytoplankton species and is an important enzyme in the photosynthetic process. To investigate the phytoplankton composition (internal driving forces), we selected the functional gene of the Rubisco large subunit (rbcL) as the target gene for this study. Phytoplankton gross primary productivity was measured using light and dark biological oxygen demand bottles to assess the carbon sequestration potential. The fundamental environmental indicators were determined to analyze the mechanisms that drive the carbon fixation process. The correlation results indicated that green algae were only controlled by nitrate, and that diatoms were positively correlated with phosphate. The cluster analysis results demonstrated that nitrite was the major driver controlling phytoplankton primary productivity. During the wet seasons (spring and summer), the contribution of the planktonic community respiration to the carbon sequestration potential was higher than net primary productivity (NPP), followed by dissolved organic carbon and nitrate. During the dry season (autumn), NPP, total nitrogen, and nitrite ranked highest in terms of carbon sequestration potential. The contributions of green algae and diatoms to the carbon sequestration potential were temporally higher than those of cyanobacteria. The maximum carbon sequestration potential occurred during autumn because of diatom production and the function of phosphate, whereas the minimum carbon sequestration potential occurred in summer. Spatially, the upstream carbon sequestration potential was higher compared with downstream because of the effect (contribution) of cyanobacteria (Phormidium), diatoms (Surirella solea and Thalassiosira pseudonana), and environmental variable (nitrite). These findings provide a better understanding of the underlying mechanisms of phytoplankton productivity and the influences of environmental variables on carbon sequestration in urban river ecosystems. [ABSTRACT FROM AUTHOR]

BACKGROUND Although microalgae had been widely used in wastewater treatment, the treatment efficiency is affected by the carbon limitation of the carbon/nitrogen (C/N) ratio in wastewater. In the present study, the performance on nutrients removal and biomass production was investigated when Chlorococcum sp. GD was inoculated into non‐sterile municipal wastewater and cattle farm wastewater. RESULTS: Although wastewater had indigenous microalgae and bacteria, microalgae could grow and the growth of indigenous bacteria was inhibited when exogenous Chlorococcum sp. GD was inoculated into non‐sterile municipal wastewater and cattle farm wastewater. Nevertheless, both biomass production and nutrients removal were relatively low due to the low C/N ratio in both wastewaters. When sodium acetate was supplemented to both wastewaters in the late exponential growth stage, biomass production and nutrients removal were enhanced. Moreover, the lipid accumulation from microalgal cells grown in municipal wastewater and cattle farm wastewater were 33.2% and 20.9%, respectively. Linoleic and linolenic acids accounted for 47.64 to 56.41% of the total fatty acids, and were in great demand for dietary supplements and aquacultures. CONCLUSION: Chlorococcum sp. GD could be a potential candidate for bioremediation of both wastewaters. The exponential sodium acetate feeding would be an efficient approach for enhancing biomass production and nutrients removal efficiency from wastewater with a low C/N ratio. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

We present light and scanning electron microscopical observations on frustules of a new species of Clipeoparvus Woodbridge et al. from Tibet. Cells are small, lens-shaped to conical, have internally occluded areolae and lack any processes. The Tibetan species differs from Clipeoparvus anatolicus Woodbridge, E.J. Cox & Roberts, the only other known species of the genus described from Turkey, by the number, size and structure of the spines on the valve face. Two morphs were encountered, one bearing spines and the other without spines, and they can occur separately or in the same frustule. This phenomenon may be an example of Janus cells within this taxon. The biogeographic distribution of this taxon is discussed. [ABSTRACT FROM AUTHOR]

BACKGROUND In this study, five microalgal species (Chlorella vulgaris, Chlorococcum sp. GD, Parachlorella kessleri TY, Scenedesmus quadricauda, and Scenedesmus obliquus) were cultivated in batch mode to evaluate their respective potential for the treatment of real aquaculture wastewater from a fishery. Subsequently, the microalga with the best performance was cultivated with different initial inoculation concentrations to evaluate the effect of initial inoculation on pollutant removal efficiency. RESULTS: When real aquaculture wastewater was inoculated with exogenous microalgae, the growth of both indigenous microalgae and bacteria was significantly inhibited. Pollutant removal was closely related to exogenous inoculation of microalgae. Parachlorellakessleri TY had high growth potential and pollutant removal capability in aquaculture wastewater, compared with the other four microalgae. When the wastewater was inoculated with low biomass concentrations of P. kessleri TY (50–100 mg L−1), it grew well and degraded most of the encountered pollutant. In particular, P. kessleri TY with 100 mg L−1 of inoculation concentration removed 94.4% of COD, 96.2% of ammonium, 99% of nitrite, 94.3% of nitrate, and 95.6% of phosphorus after 3 days of cultivation. CONCLUSIONS: Both the screening for microalgal species and the regulation of initial inoculation concentrations are promising approaches to enhance pollutant removal efficiency from real aquaculture wastewater. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Five common used green algae species, Chlorella vulgaris, Chlorococcum sp. GD, Parachlorella kessleri TY, Scenedesmus obliquus, and Scenedesmus quadricauda, were evaluated for their growth and nitrogen removal properties when being cultivated in synthetic wastewater with ammonium and nitrate as nitrogen sources. The five microalgae could adapt wastewater with different kinds of nitrogen sources, but the growth potential and nitrogen removal ability were species-dependent. Parachlorella kessleri TY cultivated in wastewater with ammonium and nitrate had higher biomass concentration of 2750 and 2765 mg L−1, respectively, compared to C. vulgaris, S. obliquus, and S. quadricauda. Chlorococcum sp. GD in wastewater with nitrate had the highest biomass concentration of 3095 mg L−1. Although all microalgae showed a good removal efficiency of nitrogen (ammonium: 85.30-97.03%; nitrate: 100%) after 7 days of cultivation, Chlorococcum sp. GD and P. kessleri TY removed 85-90.24% of ammonium and 100% of nitrate within 2-3 days, which was faster than the other three microalgae. It was also found that the growth and pollutant removal of microalgae in wastewater with nitrate was superior to those of microalgae in wastewater with ammonium. This was caused by the inhibitory effect of the low pH when microalgae were cultivated in wastewater with ammonium as the nitrogen source. Based on the results above, the growth and nitrogen removal was closely related to the microalgal species and the pH of the wastewater. [ABSTRACT FROM AUTHOR]

Arthrospira (Spirulina) platensis extract (APE) was used as a natural antioxidant in Chinese-style sausage during storage at 4 °C for 18 days. As compared to control, we examined the effect of APE on physical, chemical, microbiological, and sensory qualities of sausages, as well as on change in pH, color, thiobarbituric value (TBARS), volatile basic nitrogen (VBN), and total viable counts of mesophilic and psychrotrophic bacteria. The sensory qualities including color, aroma, taste, texture, and overall acceptability were evaluated. It was found that APE sausages displayed lower changes in pH, lightness (L*), redness (a*), yellowness (b*), TBARS value, and sensory attributes than control. However, there was no significant difference in VBN and microbiological status between APE and control sausages. Successful inhibition of lipid oxidation in samples was possible with the incorporation of APE in the refrigerated Chinese-style sausages. Our results suggest that the incorporation of APE into Chinese-style pork sausages enhance the antioxidant and maintains product quality. [ABSTRACT FROM AUTHOR]

The Rhodophyta Sheathia arcuata is exclusively distributed in freshwater, constituting an important component in freshwater flora. This study presents the first transcriptome profiling of freshwater Rhodophyta taxa. A total of 161,483 assembled transcripts were identified, annotated and classified into different biological categories and pathways based on BLAST against diverse databases. Different gene expression patterns were caused principally by different irradiances considering the similar water conditions of the sampling site when the specimens were collected. Comparison results of gene expression levels under different irradiances revealed that photosynthesis-related pathways significantly up-regulated under the weak light. Molecular responses for improved photosynthetic activity include the transcripts corresponding to antenna proteins (LHCA1 and LHCA4), photosynthetic apparatus proteins (PSBU, PETB, PETC, PETH and beta and gamma subunits of ATPase) and metabolic enzymes in the carbon fixation. Along with photosynthesis, other metabolic activities were also regulated to optimize the growing and development of S. arcuata under appropriate sunlight. Protein-protein interactive networks revealed the most responsive up-expressed transcripts were ribosomal proteins. The de-novo transcriptome assembly of S. arcuata provides a foundation for further investigation on the molecular mechanism of photosynthesis and environmental adaption for freshwater Rhodophyta. [ABSTRACT FROM AUTHOR]

This study examined the effect of Spirulina platensis polysaccharides (SPP) at 0.1%, 0.25%, and 0.5% (wt/wt) of Chinese-style sausages on lipid peroxidation, microbiological and sensory properties during 24 d stored at 4 °C. During the storage, pH, lightness (L*) values, DPPH radical scavenging activity and sensory scores decreased with time and TBARS, TVB-N, mesophilic, and psychrotrophic total viable counts increased. However, the magnitude of the changes was attenuated with the addition of SPP as compared to control. Samples containing SPP had significantly ( P ≤ 0.05) higher DPPH radical scavenging activity and lower TBARS values compared with the control, and the antioxidant effect was dose-dependent. The addition of 0.5% SPP maintained stable redness (a*) values of sausages, although there was no positive effect on the microbiological status. Moreover, the addition of SPP prevented the decrease of aroma, flavor and sensory acceptance of samples. The results suggested incorporation of SPP could decrease lipid peroxidation and improve sensory properties of Chinese-style sausage. Practical Application There is a great need for adding natural antioxidants to healthier meat and meat products. Spirulina platensis polysaccharides (SPP) had strong antioxidant activity. The addition of SPP to Chinese-style pork sausage could inhibit lipid peroxidation, to extend the shelf life of meat products. SPP were very potential to be used to replace synthetic antioxidants in meat and meat products. [ABSTRACT FROM AUTHOR]

Phenol components are major industry contaminants of aquatic environment. Among all practical methods for removing phenol substances from polluted water, activated carbon absorption is the most effective way. Here, we have produced low-cost activated carbon using Polygonum orientale Linn, a wide spreading species with large biomass. The phenol adsorption ability of this activated carbon was evaluated at different physico-chemical conditions. Average equilibrium time for adsorption was 120 min. The phenol adsorption ability of the P. orientale activated carbon was increased as the pH increases and reached to the max at pH 9.00. By contrast, the ionic strength had little effect on the phenol absorption. The optimum dose for phenol adsorption by the P. orientale activated carbon was 20.00 g/L. The dominant adsorption mechanism of the P. orientale activated carbon was chemisorption as its phenol adsorption kinetics matched with the pseudo-second-order kinetics. In addition, the equilibrium data were fit to the Langmuir model, with the negative standard free energy and the positive enthalpy, suggesting that adsorption was spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

As a kind of biofilm structure, microbial attachment was believed to play an important role in the aggregation and stability of flocculent activated sludge (FAS), and also its translation to aerobic granular activated sludge (AGAS). The aim of this study was to investigate the effect of Ca2+, Mg2+, Cu2+, Fe2+, Zn2+, K+, and Na+, which were frequently found in the biological wastewater-treatment systems on the microbial attachment of FAS, in order to provide a new strategy for the cultivation of FAS and AGAS. The results showed that different metal ions had different effects on the process of microbial attachment of FAS; in particular, Cu2+, Fe2+, and Zn2+could increase the microbial attachment ability of FAS at appropriate concentrations, and disrupted the process at higher concentrations. Mg2+would greatly enhance the microbial attachment of FAS at lower concentrations but then the biomass of attachment was fallen down to a level close to that of the control. However, Ca2+, K+, and Na+always exhibited a positive impact on the microbial attachment of FAS. Besides, the concentration of FAS suspension and the culture time both had an effect on the microbial attachment of FAS. Moreover, the acyl-homoserine-lactones-based quorum-sensing system, the content of EPS, and the relative hydrophobicity of FAS had been greatly influenced by metal ions. As all these parameters had close relationships with microbial attachment process, changes in these parameters may affect the microbial attachment of FAS. [ABSTRACT FROM PUBLISHER]

Melanoma is an aggressive skin cancer. Unfortunately, there is currently no chemotherapeutic agent available to significantly prolong the survival of the most patients with metastatic melanomas. Here we report that the Ginkgo biloba extract (EGb761), one of the most widely sold herbal supplements in the world, potently induces apoptosis in human melanoma cells by disturbing the balance between pro- and anti-apoptosis Bcl-2 family proteins. Treatment with EGb761 induced varying degrees of apoptosis in melanoma cell lines but not in melanocytes. Induction of apoptosis was caspase-dependent and appeared to be mediated by the mitochondrial pathway, in that it was associated with reduction in mitochondrial membrane potential and activation of Bax and Bak. Although EGb761 did not cause significant change in the expression levels of the BH3-only Bcl-2 family proteins Bim, Puma, Noxa, and Bad, it significantly downregulated Mcl-1 in sensitive but not resistant melanoma cells, suggesting a major role of Mcl-1 in regulating apoptosis of melanoma cells induced by EGb761. Indeed, siRNA knockdown of Mcl-1 enhanced EGb761-induced apoptosis, which was associated with increased activation of Bax and Bak. Taken together, these results demonstrate that EGb761 kills melanoma cells through the mitochondrial apoptotic pathway, and that Mcl-1 is a major regulator of sensitivity of melanoma cells to apoptosis induced by EGb761. Therefore, EGb761 with or without in combination with targeting Mcl-1 may be a useful strategy in the treatment of melanoma. [ABSTRACT FROM AUTHOR]

By separating and extracting algae from the collected water samples, an oil-producing diatom strain was obtained. Microscopic observation of the strain revealed that its morphological characteristics were highly similar to those of the genus Cyclotella. The cloning of 18S rDNA and phylogenetic analysis showed that the algae were clustered with Cyclotella menegheniana with a high support rate, indicating that the alga was C. menegheniana. The fatty acid content of the alga was determined and found to be mainly C14, C16, and C18 fatty acids, which were in accordance with the relevant standards for edible oil. In this study, different gradient levels of salinity and light were set to investigate the culture and bioactive substance production of C. menegheniana. The results showed that the best growth condition was achieved when the salinity was 15 g·L−1, and its biomass and oil content were the highest at 0.27 g·L−1 and 21%, respectively. The final biomass was the highest when the light intensity was 2000 Lux and the oil content was 18.7%. The results of the study provided a basis for the large-scale production of edible oils and biodiesel. [ABSTRACT FROM AUTHOR]

To study the relationship between β-carotene synthesis and geranylgeranyl pyrophosphate synthase (GGPS) activity, 15 species of Dunaliella were used to determine the changes in photosynthetic pigment contents, chlorophyll fluorescence parameters, β-carotene content, and GGPS activity. By observing the morphology and size of 15 species of Dunaliella, D8 has the largest individual algal cell and D9 has the smallest individual. Growth was relatively slow during days one through seven. After about eight days, the cells entered the logarithmic growth period and grew rapidly to a high density. After about 45 days, they entered a mature period, and growth slowed down. The contents of chlorophyll, carotenoids, and β-carotene increased during growth. D1 has the highest accumulation of β-carotene, and GGPS enzyme activity has a positive linear relationship with the β-carotene synthesis content. Phylogenetic analysis showed that the GGPS proteins of the 15 species were highly homologous, and the GGPS protein was not part of the membrane. [ABSTRACT FROM AUTHOR]

The combustion explosion of ordinary diesel is a global environmental problem. Green microalgae, which do not cause eutrophication, are a raw material that can be used to clean biodiesel. To increase lipid productivity, this study used a nitrogen deficient & mixotrophic (+Glucose) culture of lipid-producing microalgae Parachlorella kessleri TY from Shanxi Province, China. To examine the growth of P. kessleri TY, we measured dry weight, chlorophyll content, and chlorophyll fluorescence intensity under different culture conditions, in addition to the contents of neutral lipids, total lipids, and fatty acids, to examine its lipid accumulation ability. Cells were cultured in autotrophic, nitrogen deficient, mixotrophic (+Glucose), and nitrogen deficient & mixotrophic (+Glucose) conditions for 7 days. We found the growth of P. kessleri TY under nitrogen deficient & mixotrophic conditions was higher than that under the autotrophic and nitrogen deficient conditions, but lower than that under the mixotrophic (+Glucose) conditions. However, its lipid accumulation ability was significantly higher than that of control cultures. In conclusion, P. kessleri TY cultured under nitrogen-deficient and mixotrophic (+Glucose) conditions has significant lipid production capacity. Our results provide a theoretical basis for the use of microalgae as a raw material in the production of biodiesel, and promote the application of P. kessleri TY in large-scale production. [ABSTRACT FROM AUTHOR]

The oleaginous microalgae species Chlorococcum sphacosum GD is a promising feedstock for biodiesel production from soil. However, its metabolic mechanism of lipid production remains unclear. In this study, the lipid accumulation and metabolism mechanisms of Chlorococcum sphacosum GD were analyzed under salt stress based on transcriptome sequencing. The biomass and lipid content of the alga strain were determined under different NaCl concentrations, and total RNA from fresh cells were isolated and sequenced by HiSeq 2000 high throughput sequencing technology. As the salt concentration increased in culture medium, the algal lipid content increased but the biomass decreased. Following transcriptome sequencing by assembly and splicing, 24,128 unigenes were annotated, with read lengths mostly distributed in the 200–300 bp interval. Statistically significant differentially expressed unigenes were observed in different experimental groups, with 2051 up-regulated genes and 1835 down-regulated genes. The lipid metabolism pathway analysis showed that, under salt stress, gene-related fatty acid biosynthesis (ACCase, KASII, KAR, HAD, FATA) was significantly up-regulated, but some gene-related fatty acid degradation was significantly down-regulated. The comprehensive results showed that salt concentration can affect the lipid accumulation and metabolism of C. sphacosum GD, and the lipid accumulation is closely related to the fatty acid synthesis pathway. [ABSTRACT FROM AUTHOR]

Algae blooms present an environmental problem worldwide. In response to the outbreak of harmful algal blooms in cyanobacteria, the role of biological control has drawn wide attention, particularly for algicidal bacteria. The mechanism underlying algicidal activity was determined in our study. Algae-lysing bacteria used were separated from water and sediment collected from the Fenhe scenic spot of Taiyuan. Genetic and molecular identification was conducted by polymerase chain reaction amplification based on 16S rDNA gene. These bacterial strains were identified as Raoultella planticola and Aeromonas sp. The algae-lysing characteristics were evaluated on Microcystis aeruginosa. For the two algicidal bacteria, the high inoculation ratio (>8%) of bacteria strains contributed to the lytic effect. M. aeruginosa could be completely removed by these strains at different cell ages. However, the time used decreased with an increase in cell age. The removal rate was increased while M. aeruginosa was in the lag and logarithmic phases. The earlier bacteria strains could be inoculated, the sooner all algae could be removed. Both algicidal substances were protein, which could destroy the photosynthetic systems and break the cell of M. aeruginosa. The algicidal bacteria strain has important theoretical and practical significance for economic and feasible algae removal and provides good germplasm resources and technical support for the control of cyanobacterial bloom. [ABSTRACT FROM AUTHOR]

Understanding the relative impact sizes of environmental factors and nutrients on the high annual variation of phytoplankton abundance in eutrophic rivers is important for aquatic ecosystem management efforts. In this study, we used phytoplankton dynamic datasets in the eutrophic Fenhe River to show the variations and drivers of phytoplankton abundance under complex, fluctuating environmental conditions during 2012–2017. The temporal and spatial variations of nutrients in the river depicted that the total phosphorus (TP) concentration was higher in the wet season and in downstream. There were increases in total nitrogen (TN) concentration in the normal season and in upstream. The structural equation model (SEM) showed that the phytoplankton abundance increased during the wet season despite the decrease in the TN:TP ratio and was reduced upstream due to the highest TN:TP ratio. Among the environmental variables, water temperature (WT) was an important predictor and positively correlated temporally and spatially to phytoplankton. The interaction of nutrients with the phytoplankton community at different temperature levels indicated that different phytoplankton groups have different nutrient requirements. We can conclude that enhances in temperature and TP concentration will significantly increase phytoplankton abundance and dominance of cyanobacteria and green algae in the future, whereas there was insignificant effect on diatoms. These data indicated that temperature and TP content were the important abiotic factors influencing the phytoplankton growth of the water body, which could provide a reference for the evaluation of environmental alterations in the future. [ABSTRACT FROM AUTHOR]

In this paper, the algal cell density of cyanobacteria, green algae, and diatoms and their responses to the hydrochemical factors were analyzed to reveal the structural characteristics of water quality in an urban river. A total of nine sampling sites from upstream to downstream was explored in our study. At each site, the density of algae was identified every week during the wet season (June-October) from 2012 to 2017, and in situ detection was used for the relative 11 hydrochemical variables. The temporal and spatial characteristics of 14 variables were analyzed using a heatmap coupled with the cluster analysis method. The trend of each parameter was analyzed using the smoothing method with locally weighted regression. The nonmetric multidimensional scaling method was employed to detect the temporal and spatial similarities among algae along hydrochemical gradients. The responses of algal density to hydrochemical variables were analyzed using a redundancy analysis. The results showed that the water temperature (Wtemp), pH, dissolved oxygen (DO), cyanobacteria, and diatoms exhibited significant declining trends, and significant increasing trends were shown in the permanganate index, chemical oxygen demand, total nitrogen, ammonia nitrogen, and total phosphorus; the cyanobacteria exhibited certain differences with green algae and diatoms in summer and the downstream areas of the river. The temporal-spatial homogeneity of algal to hydrochemical variables showed the key influencing factors of Wtemp for cyanobacteria density, chlorophyll for green algae density, DO, and pH for diatoms. The results presented here are valuable for deepening our understanding of river ecosystem evaluations and effective environmental management, as well as an important reference for the sustainable development of aquatic biological resources. [ABSTRACT FROM AUTHOR]

1,4-Dichlorobenzene (1,4-DCB) is a common organic contaminant in water. To determine the effects of this contaminant on photosynthesis in the freshwater alga Chlorella pyrenoidosa, algal cells were treated with 1,4-DCB at different concentrations for various times, and their photosynthetic pigment contents and chlorophyll fluorescence traits were analyzed. The results showed that 1,4-DCB exerted toxic effects on photosynthesis in C. pyrenoidosa, especially at concentrations exceeding 10 mg/L. The inhibitory effects of 1,4-DCB were time- and concentration-dependent. After treatment with 1,4-DCB (≥10 mg/L), the contents of photosynthetic pigments decreased significantly, the photosystem II reaction center was irreversibly damaged, and the quantum yield of photosystem II decreased significantly. Also, there were sharp decreases in the efficiency of photosynthetic electron transport and energy conversion. Photosystem II became overloaded as the amount of excitation energy distributed to it increased. All of these events weakened the photochemical reaction, and ultimately led to serious inhibition of photosynthesis. [ABSTRACT FROM AUTHOR]