Ascorbate−glutathione cycle involving in response of Bangia fuscopurpurea (Bangiales, Rhodophyta) to hyposalinity

Bangia fuscopurpurea is a widespread intertidal seaweed that is commercially cultured in China. This seaweed is frequently exposed to hyposalinity stress, but little is known about the adaptation mechanisms. Ascorbate−glutathione (AsA−GSH) cycle plays important roles in many organisms under a variety of abiotic stress, including hyposaline stress. In this study, we investigated the response of key metabolites and enzymes involved in the AsA−GSH cycle of B. fuscopurpurea under hyposalinity, with the addition of exogenous GSH and Lbuthionine-sulfoximine (BSO). The quantification of BfAPX gene expression was assessed across varied treatment regimens. And the putative interaction proteins of BfAPX were screened by yeast two hybrid system. It was found that under hyposalinity (15 and/or 0 psu), the content of reduced glutathione (GSH), total glutathione (GSH+ oxidized glutathione, GSSG) and cysteine, the ratio of GSH/GSSG and ascorbic acid (AsA)/ dehydroascorbic acid (DHA), and the activity of ascorbic acid peroxidase (APX) and monodehydroascorbate reductase (MDHAR) was significantly up-regulated. The hyposality-promoted GSH/GSSG was weakened while the glutathione reductase (GR) activity was promoted by adding exogenous GSH and BSO. The hyposality-promoted AsA/DHA ratio was strengthened by exogenous GSH but weakened by BSO. The dehydroascorbate reductase (DHAR) activity had no significant changes either with or without exogenous GSH under all salinities, while DHAR activity together with DHA content was enhanced by BSO. The expression of APX gene markedly increased under hyposalinity+BSO treatment. Putative interacting proteins of APX, including glutamate dehydrogenase 1a and fructose diphosphate aldolase, were identified through screening. The results indicated that the AsA−GSH cycle was involved in response of B. fuscopurpurea to hyposalinity by means of increasing GSH/GSSG ratio (through promoting GSH biosynthesis pathway and GSH regeneration from GSSG by GR catalyzation) and AsA/DHA ratio (promoting AsA regeneration through MDHAR). These findings would contribute to improve the aquaculture of this promising economic species and unveil how intertidal seaweeds address the global climate challenges

Metabonomic analysis of follicular fluid in patients with diminished ovarian reserve

BackgroundOvarian reserve is an important factor determining female reproductive potential. The number and quality of oocytes in patients with diminished ovarian reserve (DOR) are reduced, and even if in vitro fertilization-embryo transfer (IVF-ET) is used to assist their pregnancy, the clinical pregnancy rate and live birth rate are still low. Infertility caused by reduced ovarian reserve is still one of the most difficult clinical problems in the field of reproduction. Follicular fluid is the microenvironment for oocyte survival, and the metabolic characteristics of follicular fluid can be obtained by metabolomics technology. By analyzing the metabolic status of follicular fluid, we hope to find the metabolic factors that affect the quality of oocytes and find new diagnostic markers to provide clues for early detection and intervention of patients with DOR.MethodsIn this research, 26 infertile women with DOR and 28 volunteers with normal ovarian reserve receiving IVF/ET were recruited, and their follicular fluid samples were collected for a nontargeted metabonomic study. The orthogonal partial least squares discriminant analysis model was used to understand the separation trend of the two groups, KEGG was used to analyze the possible metabolic pathways involved in differential metabolites, and the random forest algorithm was used to establish the diagnostic model.Results12 upregulated and 32 downregulated differential metabolites were detected by metabolic analysis, mainly including amino acids, indoles, nucleosides, organic acids, steroids, phospholipids, fatty acyls, and organic oxygen compounds. Through KEGG analysis, these metabolites were mainly involved in aminoacyl-tRNA biosynthesis, tryptophan metabolism, pantothenate and CoA biosynthesis, and purine metabolism. The AUC value of the diagnostic model based on the top 10 metabolites was 0.9936.ConclusionThe follicular fluid of patients with DOR shows unique metabolic characteristics. These data can provide us with rich biochemical information and a research basis for exploring the pathogenesis of DOR and predicting ovarian reserve function

Icefish (Salangidae) as an indicator of anthropogenic pollution in freshwater systems using nitrogen isotope analysis

We investigated differences in delta N-15 of seston and icefishes from seven freshwater ecosystems with different trophic states in China. An increase of seston delta N-15 values was accompanied by an increase of total nitrogen and phosphorus concentrations. Significantly positive correlations were observed between delta N-15 of icefishes and delta N-15 of seston, total nitrogen and phosphorus concentrations. This study demonstrated that icefishes could be preferred indicators of anthropogenic contamination in test systems because they integrated waste inputs over long time periods and reflected the movement of waste through the pelagic food chain.We investigated differences in delta N-15 of seston and icefishes from seven freshwater ecosystems with different trophic states in China. An increase of seston delta N-15 values was accompanied by an increase of total nitrogen and phosphorus concentrations. Significantly positive correlations were observed between delta N-15 of icefishes and delta N-15 of seston, total nitrogen and phosphorus concentrations. This study demonstrated that icefishes could be preferred indicators of anthropogenic contamination in test systems because they integrated waste inputs over long time periods and reflected the movement of waste through the pelagic food chain

Additional kinetic energy harvesting with extra electrodes by single electrode droplet-based electricity generator (SE-DEG)

The utilization of water energy through the Single Electrode Droplet-Based Electricity Generator (SE-DEG) represents a universal and high-efficiency method for water energy harvesting. Previous research has extensively elucidated the working principle of SE-DEG based on bulk effect. However, scant attention has been paid to the investigation of the electrical characteristics surrounding the SE-DEG. Remarkably, the electrical characteristics around the SE-DEG can be exploited to generate electricity and harvest corresponding energy. Here we evaluate the electrical characteristics around the SE-DEG by arranging extra electrodes. An interesting phenomenon is found that, on the premise of no contact between extra electrodes and the droplet, there is opposite electricity output from extra electrodes synchronously when the droplet contacts on the PTFE film and SE-DEG electrode and outputs the electricity. This phenomenon is comprehensively explained and verified from working mechanism, the impacts of different arrangements and the array design of extra electrodes. Significantly, utilizing the electrical characteristics could harvest additional kinetic energy with extra electrodes in SE-DEG. This investigation is expected to provide new insights into the future harnessing of water kinetic energy within the SE-DEG framework

Interaction Network Construction and Functional Analysis of the Plasma Membrane H⁺-ATPase in <i>Bangia fuscopurpurea</i> (Rhodophyta)

Salinity is a serious threat to most land plants. Although seaweeds adapt to salty environments, intertidal species experience wide fluctuations in external salinities, including hyper- and hypo-saline stress. Bangia fuscopurpurea is an economic intertidal seaweed with a strong tolerance to hypo-salinity. Until now, the salt stress tolerance mechanism has remained elusive. Our previous study showed that the expression of B. fuscopurpurea plasma membrane H+-ATPase (BfPMHA) genes were the most upregulated under hypo-salinity. In this study, we obtained the complete sequence of BfPMHA, traced the relative expression of this BfPMHA gene in B. fuscopurpurea under hypo-salinity, and analyzed the protein structure and properties based on the gene’s sequence. The result showed that the expression of BfPMHA in B. fuscopurpurea increased significantly with varying hypo-salinity treatments, and the higher the degree of low salinity stress, the higher the expression level. This BfPMHA had typical PMHA structures with a Cation-N domain, an E1-E2 ATPase domain, a Hydrolase domain, and seven transmembrane domains. In addition, through the membrane system yeast two-hybrid library, three candidate proteins interacting with BfPMHA during hypo-saline stress were screened, fructose–bisphosphate aldolase (BfFBA), glyceraldehyde 3-phosphate dehydrogenase (NADP+) (phosphorylating) (BfGAPDH), and manganese superoxide dismutase (BfMnSOD). The three candidates and BfPMHA genes were successfully transferred and overexpressed in a BY4741 yeast strain. All of them significantly enhanced the yeast tolerance to NaCl stress, verifying the function of BfPMHA in salt stress response. This is the first study to report the structure and topological features of PMHA in B. fuscopurpurea and its candidate interaction proteins in response to salt stress

Comparative Ubiquitome Analysis under Heat Stress Reveals Diverse Functions of Ubiquitination in Saccharina japonica

Ubiquitination is a major post-translational modification involved in nearly all aspects of eukaryotic biology. Previous RNA-Seq studies showed that ubiquitination plays essential roles in the heat tolerance of Saccharina japonica, but to date, large-scale profiling of the ubiquitome in S. japonica has not been reported. To better understand the regulatory roles of ubiquitination in heat responses of S. japonica, we investigated its ubiquitome under normal and heat stress by the combination of affinity enrichment and high-resolution liquid chromatography-tandem mass spectroscopy analysis. Altogether, 3305 lysine ubiquitination sites in 1562 protein groups were identified. After normalization, 152 lysine ubiquitination sites in 106 proteins were significantly upregulated and 208 lysine ubiquitination sites in 131 proteins were significantly downregulated in response to heat stress. Protein annotation and functional analysis suggested that ubiquitination modulates a variety of essential cellular and physiological processes, including but not limited to the ubiquitin-26S proteasome system, ribosome, carbohydrate metabolism, and oxidative phosphorylation. Our results provide a global view of the heat response ubiquitome in S. japonica, and could facilitate future studies on the physiological roles of these ubiquitination-related proteins

Stable silencing of &#946;-lactoglobulin (BLG) gene by lentivirus-mediated RNAi in goat fetal fibroblasts

&#946;-lactoglobulin (BLG), a dominant allergen in goat milk, is difficult to remove by traditional biochemical methods. Its elimination from goat milk by genetic modification therefore poses a major challenge for modern goat breeders. A shRNA targeting BLG mRNA with high interference efficiency was identified, with which lentiviral vectors were used for mediating stable shRNA interference in goat-fetal fibroblast cells. Apart from high efficiency in the knockdown of BLG expression in these cells, lentivector-mediated RNAi manifested stable integration into the goat genome itself. Consequently, an in vitro model for goat BLG-content control was compiled, and a goat-cell line for accompanying transgenetic goat production created

Study on the Physiological and Biochemical Influence of Sargassum thunbergii Under Dehydration

Sargassum thunbergii is distributed on reefs and rock marshes in mid- and low-tide zones, and some are periodically exposed to lengthy low tides. Dehydration is a key factor affecting the survival of S. thunbergii at low tides. In this study, using wild S. thunbergii as experimental material, the water loss rate, chlorophyll fluorescence parameters, and biochemical parameters under different stresses were determined by dehydrating the thalli in an incubator for 0, 1, 3, and 6 h. The results showed that: (1) algae of different sizes have significantly different water loss rates under different stresses. The shorter the stress time and the larger the algae, the lower the water loss rate, indicating that the water retention capacity of S. thunbergii with larger thalli is higher. Wild S. thunbergii grow in clusters on reefs. The leaves in the lower part of the branches and near the holdfast are wide. The middle and upper leaves are narrow and long, respectively. The lower broad leaves are easily blocked by the upper branches. Therefore, differences in the growth environment cause differences in the ecological structure and biochemical components of S. thunbergii. High temperature, strong light, and water loss at low tide are the main factors that cause severe environmental stress to sessile S. thunbergii in the intertidal zone. (2) Dehydration significantly reduced the chlorophyll fluorescence value of S. thunbergii, and different parts of the same individual of S. thunbergii had significantly different tolerance to dehydration, with the lowest tolerance at branch tips and the strongest tolerance at the base. The non-regulatory energy-dissipation mechanism plays a major role in the dehydration response of S. thunbergii. Under dry exposure, the light energy utilization efficiency of S. thunbergii was significantly reduced. This reduction in active light protection capacity indicates that dehydration reduces the adaptability of S. thunbergii to excessive light intensity. Dehydration can damage the tips of small individuals that cannot recover, while the base part of large individuals could return to a normal physiological state. (3) Antioxidant enzymes (ASAFR, SOD) and non-antioxidant substances (soluble sugar and proline) in the tip part responded to dehydration, and the base part mainly responded by upregulation of protein, soluble sugar, and proline content to resist stress. S. thunbergii, located in the high and middle tide zones, is more likely to be stressed by high temperatures, strong light, and dehydration, and the physiological and biochemical characteristics of different parts of the thallus are also variable due to differences in external morphology. Algae mainly reduce damage to the photosynthetic system caused by a lack of water through a non-regulatory energy dissipation mechanism. The water retention capacity of the base was better than branch tips during dry exposure, and the damage to algal cells was low. The main roles are as heat shock proteins, soluble sugars, proline, and other small molecules, which can pass stress response, osmotic regulation, and anti-oxidation resists damage to cells caused by stress. The water retention capacity of the top cells was weak, and the stress was relatively strong. Antioxidant enzymes such as ASAFR and SOD in algae and non-antioxidant enzymes such as soluble sugars and proline, work together to resist dry exposure stress, reduce cell damage and maintain cell viability. In summary, under the stress of dry exposure, the antioxidant enzymes, antioxidant substances, and non-regulatory energy dissipation mechanisms of S. thunbergii play a role in maintaining cell activity. This study provides important guidance for exploring the ecological adaptability of S. thunbergii in resisting environmental stress