Effectiveness and mechanism of in situ sludge biochar carrier enhancing salt-tolerant bacteria for pyrazolone degradation in high-salinity pharmaceutical wastewater.

Physiological and transcriptomic analysis provides new insights into osmoregulation mechanism of Ruditapes philippinarum under low and high salinity stress

Environmental stressors and lipid production by Dunaliella spp. I. Salinity

Salinity stress is one of the major factors negatively affecting growth and productivity in living organisms including plants and bacteria resulting in significant losses worldwide. Therefore, it would be fruitful to develop salinity stress tolerant useful species and also to understand the mechanism of stress tolerance. The pea DNA helicase 45 (PDH45) is a DNA and RNA helicase, homologous to eukaryotic translation initiation factor 4A (eIF-4A) and is involved in various processes including protein synthesis, maintaining the basic activities of the cell, up-regulation of topoisomerase I activity and salinity stress tolerance in plant, but its role in salinity stress tolerance in bacteria has not heretofore studied so far. This study provides an evidence for a novel function of the PDH45 gene in high salinity (NaCl) stress tolerance in bacteria (Eschericia coli, BL21 cells) also. Furthermore, it has been shown that the functionally active PDH45 gene is required to show the stress tolerance in bacteria because the single mutant (E183G or R363Q) and the double mutant (E183G + R363Q) of the gene could not confer the same function. The response was specific to Na+ ions as the bacteria could not grow in presence of LiCl. This study suggests that the cellular response to high salinity stress across prokaryotes and plant kingdom is conserved and also helps in our better understanding of mechanism of stress tolerance in bacteria and plants. It could also be very useful in developing high salinity stress tolerant useful bacteria of agronomic importance. Overall, this study provides an evidence for a novel function of the PDH45 gene in high salinity stress tolerance in bacteria.

Ascidians, particularly those highly invasive ones, are typical fouling organisms to cause significantly negative ecological and economic influence in coastal ecosystems. Stolon, which is the unique structure of some solitary ascidians to complete the essential process of adhesion, possesses extremely high tolerance to environmental stresses during biofouling and invasions. However, the mechanisms underlying environmental tolerance remain largely unknown. Here, we used the quantitative proteomics technology, isobaric tags for relative and absolute quantitation (iTRAQ), to investigate the molecular response to environmental challenges (temperature and salinity) in the stolon of a highly invasive fouling ascidian, Ciona robusta. When compared with the control, a total of 75, 86, 123, and 83 differential abundance proteins were identified under low salinity, high salinity, low temperature, and high temperature stress, respectively. Bioinformatic analyses uncovered the key pathways under both temperature and salinity stresses, including “cytoskeleton,” “signal transduction,” and “posttranslational modification,” which were involved in stolon structure stability, protein synthesis, and stress response activation. Under the low salinity stress, the “extracellular matrix” pathway was identified to play a crucial role by regulating cell signal transduction and protein synthesis. To deal with the high salinity stress, stolon could store more energy by activating “carbohydrate/lipid transport” and “catabolism” pathways. The energy generated by “lipid metabolism” pathway might be beneficial to resist the low temperature stress. The upregulation of “cell cycle” pathway could inhibit cell growth, thus helping stolon conserve more energy against the high temperature stress. Our results here provide valuable references of candidate pathways and associated genes for studying mechanisms of harsh environmental adaptation and developing antifouling strategies in marine and coastal ecosystems.

Late embryogenesis abundant proteins (LEA) are stress resistance-related proteins that play crucial roles in protecting against desiccation, cold and high salinity in a variety of animals and plants. However, the expression pattern, distribution and functions of LEA proteins in the post-diapause period of Artemia sinica, and under high salinity and low temperature stresses, remain unknown. In this study, the complete cDNA sequences of the group 1 LEA (As-g1lea) and group 3 LEA (As-g3lea) genes from A. sinica were cloned. The expression patterns and location of As-G1LEA and As-G1LEA were investigated. The protein abundances of As-G1LEA, As-G3LEA and Trehalase were analyzed during different developmental stages of the embryo and under low temperature and high salinity stresses in A. sinica. The full-length cDNA of As-g1lea was 960 bp, encoding a 182 amino acid protein, and As-g3lea was 2089 bp, encoding a 364 amino acid protein. As-g1lea and As-g3lea showed their highest expressions at 0 h of embryonic development and both showed higher relative expression in embryonic, rather than adult, development stages. The abundances of As-G1LEA, As-G3LEA and trehalose were upregulated under low temperature and downregulated under high salinity stress. These two genes did not show any tissue or organ specific expression. Our results suggested that these LEA proteins might play a pivotal role in stress tolerance in A. sinica

Combined effects of high salinity and ammonia-N exposure on the energy metabolism, immune response, oxidative resistance and ammonia metabolism of the Pacific white shrimp Litopenaeus vannamei

Molecular cloning and characterization of acyl-CoA binding protein (ACBP) gene from shrimp Penaeus monodon exposed to salinity stress

High salinity and drought seriously limit the production of many crops worldwide, including apple (Malus x. domestica Borkh). Members of the bZIP family of transcription factors play important roles in abiotic stress in various plants, but there have been few studies in perennial tree species. In our previous study, we conducted a genome-wide survey of bZIP family transcription factor genes in apple. Here, we focused on one of these genes, MdbZIP26, which is induced by high salinity, drought, and exogenous abscisic acid (ABA). The MdbZIP26 promoter contains several apparent cis-acting elements associated with abiotic stress response, such as ABRE/G-box, DRE, GT1, and GMSCAM4. The temporal and spatial expression patterns of MdbZIP26 were consistent with a role in abiotic stress response. Arabidopsis thaliana plants expressing MdbZIP26 showed enhanced tolerance to dehydration and salinity, and this was associated with altered expression of ABA/stress-regulated genes. Considered together, these results suggest that MdbZIP26 plays a role in the resistance of drought and high salinity stress in apple via ABA-mediated signaling.

Molecular cloning, characterization, and expression analysis of a heat shock protein (HSP) 70 gene from Paphia undulata

The unconventional halotolerant yeast Debaryomyces hansenii is of great importance in biotechnology and the food industry, and in basic research it serves as a model for studying the molecular mechanisms of resistance to increased salinity and osmotic stress. We have previously established an efficient method for editing the D. hansenii genome using the CRISPR/Cas9 system. In turn, this has stimulated further investigation of the structure and physiological role of DNA double-strand break repair pathways in D. hansenii. The aim of the present work was to evaluate the involvement of key components of the DNA double-stranded break repair system by the non-homologous end joining (NHEJ) mechanism in the resistance of D. hansenii to DNA-damaging compounds and compounds that induce oxidative, high salinity, and osmotic stress. Using the CRISPR/Cas9 system, mutant strains with knockout of the DEHA2F10208g (DhKU70), DEHA2B01584g (DhKU80) , and DEHA2G04224g (DhLIG4) genes encoding key components of NHEJ were obtained. It was found that mutant strains, unlike the wild-type strain, are sensitive to chemical compounds that damage DNA, as well as to compounds that cause oxidative stress. Osmotic and high salinity stresses and vanillin do not cause significant changes in the rate of colony formation of mutant strains. Unexpectedly, mutant strains exhibit increased resistance to caffeine compared to the wild-type strain. The data indicate that the NHEJ systems of D. hansenii play a significant role in the response to DNA-damaging and oxidative types of stress. The importance of the NHEJ system in the processes of maintaining yeast cell homeostasis should be taken into account when creating strains producing valuable substances.

Transcriptomic analysis reveals that selenium-enriched Lactobacillus plantarum alleviates high -salinity stress in common carp through lipid metabolism and ferroptosis signalling pathways.

Species inhabiting the North American west coast intertidal must tolerate an extremely variable environment, with large fluctuations in both temperature and salinity. Uncovering the mechanisms for this tolerance is key to understanding species' persistence. We tested for differences in salinity tolerance between populations of Tigriopus californicus copepods from locations in northern (Bodega Reserve) and southern (San Diego) California known to differ in temperature, precipitation and humidity. We also tested for differences between populations in their transcriptomic responses to salinity. Although these two populations have ~20% mtDNA sequence divergence and differ strongly in other phenotypic traits, we observed similarities in their phenotypic and transcriptomic responses to low and high salinity stress. Salinity significantly affected respiration rate (increased under low salinity and reduced under high salinity), but we found no significant effect of population on respiration or a population by salinity interaction. Under high salinity, there was no population difference in knock-down response, but northern copepods had a smaller knock-down under low salinity stress, corroborating previous results for T.californicus. Northern and southern populations had a similar transcriptomic response to salinity based on a principle components analysis, although differential gene expression under high salinity stress was three times lower in the northern population compared to the southern population. Transcripts differentially regulated under salinity stress were enriched for "amino acid transport" and "ion transport" annotation categories, supporting previous work demonstrating that the accumulation of free amino acids is important for osmotic regulation in T.californicus.

Salinity is one of the most significant environmental factors limiting plant development and productivity. Invasive plants could quickly respond to environmental changes, thus successfully achieving invasion. However, there is limited research on the mechanism of salt responses in invasive plants under different nutritional conditions. This study evaluated and compared the impact of salinity stress and nutrient application on physiological responses in the invasive plant Wedelia trilobata and native plant Wedelia chinensis. Mild salinity stress disrupted the growth of these two plants, significantly reducing their leaf and stem node number under a low nutrient condition. W. trilobata showed notable decreases in height and leaf number with high salinity stress regardless of nutrient levels, whereas it was observed only in the low nutrient state in W. chinensis. The negative effects of high salinity on both species were most evident in nutrient-poor environments. Under low salinity and nutrient stress, W. trilobata's leaves exhibited increased levels of proline, MDA, CAT, and ABA, with decreased GA and IAA content. A low-salt environment favored W. trilobata's competitive advantage, and nutrient enrichment appeared to enhance its invasive potential, in which process the plant antioxidant system and endogenous hormones contribute greatly. This study provides a theoretical foundation for predicting suitable growth areas for W. trilobata referring to the salt condition, guiding future strategies for preventing and controlling its invasive spread.

Raffinose family oligosaccharides (RFO) accumulating during seed development are thought to play a role in the desiccation tolerance of seeds. However, the functions of RFO in desiccation tolerance have not been elucidated. Here we examine the functions of RFO in Arabidopsis thaliana plants under drought- and cold-stress conditions, based on the analyses of function and expression of genes involved in RFO biosynthesis. Sugar analysis showed that drought-, high salinity- and cold-treated Arabidopsis plants accumulate a large amount of raffinose and galactinol, but not stachyose. Raffinose and galactinol were not detected in unstressed plants. This suggests that raffinose and galactinol are involved in tolerance to drought, high salinity and cold stresses. Galactinol synthase (GolS) catalyses the first step in the biosynthesis of RFO from UDP-galactose. We identified three stress-responsive GolS genes (AtGolS1, 2 and 3) among seven Arabidopsis GolS genes. AtGolS1 and 2 were induced by drought and high-salinity stresses, but not by cold stress. By contrast, AtGolS3 was induced by cold stress but not by drought or salt stress. All the GST fusion proteins of GST-AtGolS1, 2 and 3 expressed in Escherichia coli had galactinol synthase activities. Overexpression of AtGolS2 in transgenic Arabidopsis caused an increase in endogenous galactinol and raffinose, and showed reduced transpiration from leaves to improve drought tolerance. These results show that stress-inducible galactinol synthase plays a key role in the accumulation of galactinol and raffinose under abiotic stress conditions, and that galactinol and raffinose may function as osmoprotectants in drought-stress tolerance of plants.

Chapter Twenty-Four - Mechanisms of High Salinity Tolerance in Plants