Energy metabolism and metabolomics response of Pacific white shrimp Litopenaeus vannamei to sulfide toxicity

An integrated investigation of major environmental stressors on the Pacific white shrimp Litopenaeus vannamei

Ammonia, nitrite and sulfide are major environmental stressors in aquaculture. They can injury tissue structure, interfere with the immune system, impair growth and development, and make aquatic animals more vulnerable to infections. In the present study, four groups were set up as Control group (no treatment), Ammonia group (30 mg/L ammonia-N), Nitrite group (60 mg/L nitrite-N) and Sulfide group (4 mg/L sulfide), so as to examine the effects of different environmental stressors on histopathology, immune indices and transcriptome of Litopenaeus vannamei. After 48 h stimulation, the results showed that all the three environmental stressors caused damage to the hepatopancreas, midgut, muscle and gill tissues of the shrimp, and that the hepatopancreas and midgut were the most seriously damaged and the muscle was the least affected. Superoxide dismutase (SOD) activity increased and total antioxidant capacity (T-AOC) activity decreased in all the three treatment groups. Glutathione peroxidase (GSH-PX) activity decreased significantly in Sulfide group and alkaline phosphatase (AKP) activity increased significantly in Ammonia and Nitrite groups. In the hepatopancreas of the Ammonia, Nitrite, and Sulfide groups, transcriptome analysis revealed 709, 715 and 289 differential expressed gene (DEGs), respectively. GO and KEGG enrichment demonstrated that the three environmental stressors had an impact on the shrimp's immune response, metabolic processes, growth and development. The combination of histopathology, immune indicators, and transcriptome yielded that the Nitrite group had the most serious impact on the shrimp, followed by Ammonia group, while Sulfide group had the least impact.

Integration of Gut Microbiota with Transcriptomic and Metabolomic Profiling Reveals Growth Differences in Male Giant River Prawns (Macrobrachium rosenbergii)

The giant freshwater prawn (GFP; Macrobrachium rosenbergii), a tropical species cultured worldwide, has high market demand and economic value. Male GFP growth varies considerably; however, the mechanisms underlying these growth differences remain unclear. In this study, we collected gut and hemolymphatic samples of large (ML), medium (MM), and small (MS) male GFPs and used the 16S rRNA sequencing and liquid chromatography-mass spectrometry-based metabolomic methods to explore gut microbiota and metabolites associated with GFP growth. The dominant bacteria were Firmicutes and Proteobacteria; higher growth rates correlated with a higher Firmicutes/Bacteroides ratio. Serum metabolite levels significantly differed between the ML and MS groups. We also combined transcriptomics with integrative multiomic techniques to further elucidate systematic molecular mechanisms in the GFPs. The results revealed that Faecalibacterium and Roseburia may improve gut health in GFP through butyrate release, affecting physiological homeostasis and leading to metabolic variations related to GFP growth differences. Notably, our results provide novel, fundamental insights into the molecular networks connecting various genes, metabolites, microbes, and phenotypes in GFPs, facilitating the elucidation of differential growth mechanisms in GFPs.

The Pathogenic Mechanism of Enterocytozoon hepatopenaei in Litopenaeus vannamei

Enterocytozoon hepatopenaei (EHP) is a parasite in shrimp farming. EHP mainly parasitizes the hepatopancreas of shrimp, causing slow growth, which severely restricts the economic income of shrimp farmers. To explore the pathogenic mechanism of EHP, the host subcellular construction, molecular biological characteristics, and mitochondrial condition of Litopenaeus vannamei were identified using transmission electron microscopy (TEM), real-time qPCR, an enzyme assay, and flow cytometry. The results showed that EHP spores, approximately 1 μm in size, were located on the cytoplasm of the hepatopancreas. The number of mitochondria increased significantly, and mitochondria morphology showed a condensed state in the high-concentration EHP-infected shrimp by TEM observation. In addition, there were some changes in mitochondrial potential, but apoptosis was not significantly different in the infected shrimp. The qPCR results showed that the gene expression levels of hexokinase and pyruvate kinase related to energy metabolism were both upregulated in the diseased L. vannamei. Enzymatic activity showed hexokinase and lactate dehydrogenase were significantly increased in the shrimp infected with EHP, indicating EHP infection can increase the glycolysis process and decrease the oxidative phosphorylation process of L. vannamei. Previous transcriptomic data analysis results also support this conclusion.

Desulfurization properties, pathways, and potential applications of two novel and efficient chemolithotrophic sulfur-oxidizing strains of Pseudomonas sp. GHWS3 and Sphingobacterium sp. GHWS5

With the accelerated modernization of agriculture and industry, sulfides have been released into the environment as a by-products of various production processes. Elevated levels of sulfide pose a threat to organisms' health and disrupt ecosystem equilibrium. This study successfully isolated two highly efficient sulfur-oxidizing strains, namely Pseudomonas aeruginosa GHWS3 and Sphingobacterium sp. GHWS5. Neither strain exhibited hemolytic activity or pathogenicity. Additionally, GHWS3 inhibited the common aquaculture pathogen Vibrio anguillarum, while GHWS5 exhibited inhibitory effects against Vibrio harveyi. GHWS3 and GHWS5 demonstrated effective removal of sulfide under the following conditions: temperature range of 20-40 °C, pH level of 4.5-8.5, salinity range of 0-50‰, C/N ratio of 5-15, and sulfide concentration of 20-200 mg/L. By amplifying the key functional genes of the sulfur-oxidizing Sox and rDsr systems in both GHWS3 and GHWS5 strains, potential desulfurization pathways were analyzed. Furthermore, both strains displayed high efficiency in removing sulfides from actual aquaculture pond substrate mixtures. The findings of this study provide two promising candidate strains for sulfides removal from farm tailwater, industrial wastewater, and domestic wastewater.

Metabolomic responses based on transcriptome of the hepatopancreas in Exopalaemon carinicauda under carbonate alkalinity stress

High carbonate alkalinity is one of the major stress factors for survival of aquatic animals in saline-alkaline water. Exopalaemon carinicauda is a good model for studying the saline-alkaline adaption mechanism in crustacean because of its great adaptive capacity to alkalinity stress. In this study, non-targeted liquid chromatography-mass spectrometry (LC-MS) metabolomics analyses based on high-throughput RNA sequencing (RNA-Seq) were used to study the metabolomic responses of hepatopancreas in E. carinicauda at 12 h and 36 h after acute carbonate alkalinity stress. The results revealed that most of the significantly differential metabolites were related to the lipid metabolism. In particular, the sphingolipid metabolism was observed at 12 h, the glycerophospholipid metabolism was detected at 36 h, and the linoleic acid metabolic pathway was significantly enriched at both 12 h and 36 h. The combined transcriptome and metabolome analysis showed that energy consumption increased at 12 h, resulting in significant enrichment of AMPK signaling pathways, which contributed to maintain energy homeostasis. Subsequently, the hepatopancreas provided sufficient energy supply through cAMP signaling pathway and glycerophosphate metabolism to maintain normal metabolic function at 36 h. These findings might help to understand the molecular mechanisms of the E. carinicauda under carbonate alkalinity stress, thereby promote the research and development of saline-alkaline resistant shrimp.

Development of microbial enrichments for simultaneous removal of sulfur and nitrogenous metabolites in saline water aquaculture

AIM

The aim of the study was to develop microbial enrichments from the nitrifying microbial consortia and the environment for simultaneous removal of ammonia, nitrate, and sulfide in aquaculture systems at varied salinities.

METHODS AND RESULTS

Sulfur and nitrogen metabolites are the major factors affecting the farmed aquatic animal species and deteriorate the receiving environments causing ecological damage. The present study reports the development of microbial enrichments from the nitrifying microbial consortia and the environment. The enrichments used thiosulfate or thiocyanate as an energy source and simultaneously removed sulfur, ammonia, and nitrite in spiked medium (125 mg/l ammonia; 145 mg/l nitrite). Further, the microbes in the enrichments could grow up to 30 g/l salinity. Metagenomic studies revealed limited microbial diversity suggesting the enrichment of highly specialized taxa, and co-occurrence network analysis showed the formation of three micro-niches with multiple interactions at different taxonomic levels.

CONCLUSIONS

The ability of the enrichments to grow in both organic and inorganic medium and simultaneous removal of sulfide, ammonia, and nitrite under varied salinities suggests their potential application in sulfur, nitrogen, and organic matter-rich aquaculture pond environments and other industrial effluents.

Microbial biogeochemical cycling reveals the sustainability of the rice-crayfish co-culture model

Aquaculture has great potential in nourishing the global growing population, while such staggering yields are coupled with environmental pollution. Rice-crayfish co-culture models (RCFP) have been widely adopted in China due to their eco-friendliness. However, little is known about RCFP's microbiome pattern, which hinders our understanding of its sustainability. This study has conducted metagenomic analysis across aquaculture models and habitats, which revealed aquaculture model-specific biogeochemical cycling pattern (e.g., nitrogen (N), sulfur (S), and carbon (C)): RCFP is advantageous in N-assimilation, N-contamination, and S-pollutants removal, while non-RCFP features N denitrification process and higher S metabolism ability, producing several hazardous pollutants in non-RCFP (e.g., nitric oxide, nitrogen monoxide, and sulfide). Moreover, RCFP has greater capacity for carbohydrate enzyme metabolism compared with non-RCFP in environmental habitats, but not in crayfish gut. Collectively, RCFP plays an indispensable role in balancing aquaculture productivity and environmental protection, which might be applied to the blue transformation of aquaculture.

Hemocytes in blue mussel Mytilus edulis adopt different energy supply modes to cope with different BDE-47 exposures

The energetic response of blue mussel Mytilus edulis when coping with tetrabromodiphenyl ether (BDE-47) exposure was evaluated from the perspective of alterations in energy supply mode, and the possible regulating mechanism was discussed based on a 21-day bioassay. The results showed that the energy supply mode changed with concentration: 0.1 μg/L BDE-47 decreased the activity of isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), malate dehydrogenase and oxidative phosphorylation, suggesting inhibition of the tricarboxylic (TCA) acid cycle and aerobic respiration. The coincident increase in phosphofructokinase and the decrease in lactate dehydrogenase (LDH) indicated that glycolysis and anaerobic respiration were increased. When exposed to 1.0 μg/L BDE-47, M. edulis mainly utilized aerobic respiration, but lowered glucose metabolism as indicated by the decrease in glutamine and l-leucine was suggested to be involved in this process, which was differed from that in the control. The reoccurrence of IDH and SDH inhibition as well as LDH elevation indicated attenuation of aerobic and anaerobic respiration when the concentration increased to 10 μg/L, but severe protein damage was evidenced based on the elevation of amino acids and glutamine. Under the 0.1 μg/L BDE-47, activation of the AMPK-Hif-1a signaling pathway promoted the expression of glut1, which was the potential mechanism for the improvement of anaerobic respiration, and further activated glycolysis and anaerobic respiration. This study shows that the energy supply mode experienced a conversion from aerobic respiration under normal conditions to anaerobic mode in the low BDE-47 treatment and back to aerobic respiration with increasing BDE-47 concentrations, which may represent a potential mechanism for mussel physiological responses when faced with different levels of BDE-47 stress.

Sulfide causes histological damage, oxidative stress, metabolic disorders and gut microbiota dysbiosis in juvenile sea cucumber Apostichopus japonicus Selenka

Sulfide is a common harmful substance in sediments, with an especially high risk for deposit feeder organisms. The sea cucumber Apostichopus japonicus is a typical benthic feeder, and its intestine is the first line of defense and serves as a crucial barrier function. In this study, histological, physiological, gut microbiota, and metabolomic analyses were performed to explore the toxic response in the intestine of juvenile A. japonicus exposed to 0, 0.8, and 1.6 mg/L sulfide stress for 96 h. The results revealed sulfide-induced intestinal inflammatory symptoms and oxidative stress. Moreover, gut bacterial composition was observed after sulfide exposure, with an increase in Proteobacteria and a decrease in Cyanobacteria and Planctomycetes. Specifically, sulfide increased a set of sulfide-removing bacteria and opportunistic pathogens while decreasing several putative beneficial substance-producing bacteria. The metabolomic analysis indicated that sulfide also disturbed metabolic homeostasis, especially lipid and energy metabolism, in intestine. Interestingly, several intestinal bacteria were further identified to be significantly correlated with metabolic changes; for example, the decreased abundance levels of Bacillus, Corynebacterium, and Psychromonas were positively correlated with important energy metabolites, including maleic acid, farnesyl pyrophosphate, thiamine, butynoic acid, and deoxycholic acid. Thus, our research provides new insights into the mechanisms associated with the intestinal metabolic and microbiota response involved in sulfide stress adaptation strategies of juvenile A. japonicus.

Comprehensive transcriptional and metabolomic analysis reveals the neuroprotective mechanism of dietary gamma-aminobutyric acid response to hypoxic stress in the Chinese mitten crab (Eriocheir sinensis)

Hypoxia is one of the serious stress challenges that aquatic animals face throughout their life. Our previous study found that hypoxia stress could induce neural excitotoxicity and neuronal apoptosis in Eriocheir sinensis, and observed that gamma-aminobutyric acid (GABA) has a positive neuroprotective effect on juvenile crabs under hypoxia. To reveal the neuroprotective pathway and metabolic regulatory mechanism of GABA in E. sinensis exposed to hypoxia stress, an 8-week feeding trial and acute hypoxia challenge were performed. Subsequently, we performed a comprehensive transcriptomic and metabolomic analysis of the thoracic ganglia of juvenile crabs. Differential genes and differential metabolites were co-annotated to 11 KEGG pathways, and further significant analysis showed that only the sphingolipid signaling pathway and the arachidonic acid metabolism pathway were significantly enriched. In the sphingolipid signaling pathway, GABA treatment significantly increased long-chain ceramide content in thoracic ganglia, which exerted neuroprotective effects by activating downstream signals to inhibit hypoxia-induced apoptosis. Moreover, in the arachidonic acid metabolism pathway, GABA could increase the content of neuroprotective active substances and reduce the content of harmful metabolites by regulating the metabolism of arachidonic acid for inflammatory regulation and neuroprotection. Furthermore, the decrease of glucose and lactate levels in the hemolymph suggests the positive role of GABA in metabolic regulation. This study reveals the neuroprotective pathways and possible mechanisms of GABA in juvenile E. sinensis exposed to hypoxia stress and inspires the discovery of new targets for improving hypoxia tolerance in aquatic animals.

Metabolism responses in the intestine of Oreochromis mossambicus exposed to salinity, alkalinity and salt-alkalinity stress using LC-MS/MS-based metabolomics

Multiple abiotic stresses are imposed on fish as a result of unprecedented changes in temperature and precipitation patterns in recent decades. It is unclear how teleosts respond to severe ambient salinity, alkalinity, and saline-alkalinity in terms of their metabolic and molecular osmoregulation processes. The metabolic reactions in the intestine of Oreochromis mossambicus under salinity (25 g/L, S_C), alkalinity (4 g/L, A_C), and saline-alkalinity (salinity: 25 g/L & alkalinity: 4 g/L, SA_C) stresses were examined in this research utilizing LC-MS/MS-based metabolomics. The findings demonstrated that the three osmotic-stressed groups' metabolic profiles were considerably different from those of the control group. Osmolytes, energy sources, free amino acids, and several intermediate metabolites were all synthetically adjusted as part of the osmoregulation associated with the salinity, alkalinity, and saline-alkalinity stress. Following osmotic stress, osmoregulation-related pathways, including the mTOR signaling pathway, TCA cycle, glycolysis/gluconeogenesis, etc., were also discovered in the intestine of O. mossambicus. Overall, our findings can assist in better comprehending the molecular regulatory mechanism in euryhaline fish under various osmotic pressures and can offer a preliminary profile of osmotic regulation.

Responses of digestive metabolism to marine heatwaves in pearl oysters

Marine heatwaves (MHWs) have increased in intensity and frequency in global oceans, causing deleterious effects on many marine organisms and ecosystems they support. Bivalves are among the most vulnerable taxonomic groups to intensifying MHWs, yet little is known about the underlying mechanisms. Here, we investigated the impact of MHWs on the digestive metabolism of pearl oysters (Pinctada maxima). Two moderate and severe scenarios of MHWs were performed by increasing seawater temperature respectively from 24 °C to 28 °C and 32 °C for 3 days. When subjected to MHWs and with increasing intensity, pearl oysters significantly enhanced their digestive enzymatic activities, such as lipase and amylase. LC-MS-based metabolomics revealed negative responses in the lipid metabolism (e.g., steroid biosynthesis, glycerophospholipid metabolism, and sphingolipid metabolism), the amino acid metabolism (e.g., glutamate, histidine, arginine, and proline), and the B-vitamins metabolism. These findings indicate that the digestive metabolism of marine bivalves can likely succumb to intensifying MHWs events.

Metabolomic analysis predicted changes in growth rate in Daphnia magna exposed to acetaminophen

As urbanization and the global population increases, pollutants associated with municipal wastewater such as pharmaceuticals are becoming more prevalent in aquatic environments. Acetaminophen (paracetamol) is a widely used drug worldwide and one of the most frequently detected pharmaceuticals in freshwater ecosystems. This study investigated the impact of acetaminophen on the metabolite profile of Daphnia magna at two life stages; and used these metabolomic findings to hypothesize a potential impact at a higher organismal level which was subsequently tested experimentally. Targeted polar metabolite analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to measure changes in the concentration of 51 metabolites in the neonate (> 24 h old) and adult (8 day-old) daphnids following a 48-h exposure to sub-lethal concentrations of acetaminophen. The impact of acetaminophen on the metabolic profile of neonates was widely different from adults. Also, acetaminophen exposure perturbed the abundance of nucleotides more extensively than other metabolites. The acute metabolomic experimental results led to the hypotheses that exposure to sub-lethal concentrations of acetaminophen upregulates protein synthesis in D. magna and subsequently increases growth during early life stages and has an opposite impact on adults. Accordingly, a 10 day growth rate experiment indicated that exposure to acetaminophen elevated biomass production in neonates but not in adults. These novel findings demonstrate that a targeted analysis and interpretation of the changes in the polar metabolic profile of organisms in response to environmental stressors could be used as a tool to predict changes at higher biological levels. As such, this study further emphasizes the incorporation of molecular-level platforms as critical and robust tools in environmental assessment frameworks and biomonitoring of aquatic ecosystems.

Acute sulfide exposure induces hemocyte toxicity and microbiota dysbiosis in blood clam Tegillarca granosa

Sulfide are widely accumulated in aquatic environments under anaerobic conditions, which cause health problems of aquatic animals, yet their toxic effects to benthic bivalves are not well understood. We investigated the effects of sulfide on innate immunity of the blood clam Tegillarca granosa. Immunity-related indicators and hemolymph microbiota were investigated in the clams exposed to sulfide (via 10, 100 and 1000 μmol/L of Na₂S) over a 7-day period. The results showed that cellular immune responses in T. granosa were affected by exposure to high sulfide concentration (1000 μmol/L Na₂S), as indicated by total counts of hemocytes (THC), cell viability, ROS levels and phagocytic activities, suggesting that sulfide stress induces T. granosa more vulnerable to pathogen challenges. In addition, the Na₂S-induced stress also reshaped the hemolymph microbial community structure of T. granosa that some original genera decreased, such as Lactobacillus, Desulfovibrio and Akkermansia; some genera increased, such as Vibrio and Pseudoalteromonas in sulfide stress group. Sulfide exposure promoted the proliferation of opportunistic pathogen and reduced the diversity of microbial community in the hemolymph of T. granosa. In summary, sulfide stress had marked hemocytotoxicity, reduced immune-cell activity and increased bacterial infections in the blood clam.

Changes in metabolic profiling of whiteleg shrimp (Penaeus vannamei) under hypoxic stress

Hypoxia is a common concern in shrimp aquaculture, affecting growth and survival. Although recent studies have revealed important insights into hypoxia in shrimp and crustaceans, knowledge gaps remain regarding this stressor at the molecular level. In the present study, a gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach was employed to characterize the metabolic signatures and pathways underlying responses of Pacific white shrimp (Penaeus vannamei) to hypoxia and to identify associated candidate biomarkers. We compared metabolite profiles of shrimp haemolymph before (0 h) and after exposure to hypoxia (1 & 2 h). Dissolved oxygen levels were maintained above 85 % saturation in the control and before hypoxia, and 15 % saturation in the hypoxic stress treatment. Results showed 44 metabolites in shrimp haemolymph that were significantly different between before and after hypoxia exposure. These metabolites were energy-related metabolites (e.g., intermediates of citric acid cycle, lactic acid, alanine), fatty acids and amino acids. Pathway analysis revealed 17 pathways that were significantly affected by hypoxia. The changes in metabolites and pathways indicate a shift from aerobic to anaerobic metabolism, disturbance in amino acid metabolism, osmoregulation, oxidative damage and Warburg effect-like response caused by hypoxic stress. Among the altered metabolites, lactic acid was most different between before and after hypoxia exposure and had the highest accurate value for biomarker identification. Future investigations may validate this molecule as a stress biomarker in aquaculture. This study contributes to a better understanding of hypoxia in shrimp and crustaceans at the metabolic level and provides a base for future metabolomics investigations on hypoxia.

Antioxidant, Transcriptomic and Metabonomic Analysis of Hepatopancreatic Stress Resistance in Exopalaemon carinicauda Following Astaxanthin Feeding

Astaxanthin (Axn) is a xanthophyll carotenoid that has previously been shown to suppress hepatic inflammation, reduce oxidative liver damage, and improve metabolic profiles. Exopalaemon carinicauda (E. carinicauda) is an economically important fishery species in China that has been found to exhibit increased body weight following Axn feeding as compared to a standard diet. In this study, dietary Axn can significantly decreased MDA content, T-AOC and significantly increased SOD, GSH and CAT activities in shrimp hepatopancreas. Moreover, transcriptome and metabolome of E. carinicauda after Axn feeding were investigated to identify the mechanism of the effect of Axn on E. carinicauda. The transcriptomic data revealed that a total 99 different expression genes (DEGs) were identified between the Axn and control groups, of which 47 and 52 were upregulated and downregulated, respectively. DEGs of E. carinicauda such as catherpsin, actin and PARP after Axn feeding were associated with apoptosis and immune system. The metabolomic analysis revealed that A total of 73 different expression metabolites (DEMs) were identified in both metabolites, including 30 downregulated metabolites and 43 upregulated metabolites. And Axn participate in metabolism processes in hepatopancreas of E. carinicauda, including the TCA cycle, amino acid metabolism and lipid metabolism. The multiple comparative analysis implicated that Axn can improve the antioxidant capacity of hepatopancreas and the energy supply of hepatopancreas mitochondria, and then improve the ability of anti-apoptosis. Collectively, all these results will greatly provide new insights into the molecular mechanisms underlying tolerance of adverse environment in E. carinicauda.

Evaluation of immune stimulatory products for whiteleg shrimp (Penaeus vannamei) by a metabolomics approach

The use of probiotics, prebiotics and dietary fiber has become a common practice in shrimp aquaculture as alternatives to antibiotic treatment. However, not much is known about the metabolic mechanisms underlying the effects of probiotics and immunostimulant used in shrimp aquaculture. In this study, a gas chromatography-mass spectrometry (GC-MS) based metabolomics approach was used to characterize metabolite profiles of haemolymph and gills of whiteleg shrimp (Penaeus vannamei) exposed to four treatments (cellulose fiber, probiotics with Vibrio alginolyticus, a combination of cellulose fiber and V. alginolyticus and a control treatment). The cellulose fiber was administrated as a feed additive (100 mg⋅Kg^-1 feed), while the probiotics was applied in the water (10⁵ UFC⋅mL^-1 culture water). The results showed significant differences in haemolymph metabolite profiles of immune stimulated treatments compared to the control and among treatments. The combination of cellulose fiber and probiotics resulted in greater differences in metabolic profiles, suggesting a better immune stimulation with this approach. The changes in haemolymph metabolome of treated shrimp reflected several biochemical pathway modifications, including changes in amino acid and fatty acid metabolism, disturbances in energy metabolism and antimicrobial activity and stress responses. For gill tissues, significant differences were only found in lactic acid between the probiotic group and the control. Among the altered metabolites, the increases of itaconic acid in haemolymph, and lactic acid in both haemolymph and gill tissues of immune-stimulated suggest the potential use of these metabolites as biomarkers for health assessment in aquaculture.

Ammonia stress disrupts intestinal microbial community and amino acid metabolism of juvenile yellow catfish (Pelteobagrus fulvidraco)

Ammonia has adverse effects on aquatic animals, which is also widely distributed in natural aquatic environments and intensive aquaculture systems. The intestine is a primary defensive line for aquatic animals, the accumulation of ammonia in the aquatic environment can cause irreversible damage to intestinal function. In this study, we investigated the effects of acute ammonia stress on the reaction characteristics of digestive function, amino acid metabolism, and the variation in the intestinal microbiota of juvenile yellow catfish (Pelteobagrus fulvidraco). Thus, the yellow catfish was placed in water with the addition of ammonia at 0 (control), 14.6, and 146 mg/L total ammonia nitrogen for 96-h. The present study observed that ammonia accumulated in the intestine and muscle (ammonia contents in the intestine and muscle increased) and induced the activities of protein digestive enzymes dysfunction (pepsin increased while trypsin decreased). Ammonia stress changed various amino acids composition (proline, arginine, lysine, histidine, phenylalanine, tyrosine, leucine, isoleucine, valine, alanine, glutamic acid, tyrosine, and aspartic acid contents were increased in muscle) and increased the activities of alanine aminotransferase and aspartate aminotransferase in muscle. Furthermore, through 16 S rRNA gene analysis, ammonia stress-induced reduction in diversity, richness, and evenness and structure of microbiota alteration in the intestine. At the phylum level, the abundance of Fusobacteria increased while Firmicutes and Actinobacteria decreased significantly. At the genus level, the abundance of beneficial microbiota Cetobacterium significantly increased after ammonia stress. In conclusion, activation of amino acid synthesis in muscle may be involved in ammonia detoxification after severe ammonia stress. The accumulation of ammonia can disrupt the intestinal digestive function and intestinal microbiota community. The Cetobacterium may be a new potential positive factor in the resistance of ammonia toxicity.

Control of toxic sulfide in mariculture environment by iron-coated ceramsite and immobilized sulfur oxidizing bacteria

Hydrogen sulfide (H₂S) is considered one of the serious toxic pollutants in mariculture environment. Consequently, it is necessary to develop an effective strategy to prevent the production of sulfide. In this study, we modified the ceramsite with iron (ICC) and prepared a microbial agent, i.e., the immobilized sulfur-oxidizing-bacterium on the ICC (SICC), the microbial agent was following dosed in the simulated mariculture systems to control the sulfide pollutant. Results showed that the sulfide removal capacity of the new material ICC reached to 3.42 mg S g^-1 in 24 h. Comparably, the microbial agent SICC presented a stable capability in oxidizing sulfide and the sulfide removal was above 65% in test media feeding with 600 mg L^-1 sulfide even after five times of recycling. The microcosm experiments conducted in the simulated mariculture systems showed that the application of the ICC together with the SICC was able to quickly remove the existing sulfide and persistently inhibit the production of sulfide, the immobilized sulfur-oxidizing-bacterium survived stably in the new environment accounting for 1.22% of total microbial community. Therefore, dosing the ICC and SICC simultaneously might be a preferable strategy and presented a promising perspective in remediating the deteriorated mariculture environment.

Metabolomics comparison of metabolites and functional pathways in the gills of Chlamys farreri under cadmium exposure

The biological processes of Chlamys farreri (C. farreri), an economically important shellfish, are affected when exposed to Cd²⁺. In this study, changes to biological processes and metabolite levels in C. farreri were examined when exposed to Cd²⁺. Ultra-performance liquid chromatography-tandem TOF mass spectrometry (UPLC-TOF/MS)-based untargeted metabolomics was used to examine changes in the metabolism of C. farreri gill tissue exposed to 0.050 mg/L Cd²⁺ for 96 h in a natural environment. Sixty-eight metabolites with significant differences were screened by multivariate statistical analysis. Eleven enriched functional pathways displayed significant changes in inactivity. Differential metabolites, mainly C00157 and C00350, have a significant impact on functional pathways and can be used as potential major biomarkers. Lipid phosphorylation, disruption of signal transduction, and autophagy activation were observed to change in C. farreri when exposed to Cd. The metabolome information supplements research on C. farreri exposure to heavy metals and provides a platform for further multi-omics analysis.

Molecular mechanisms of zooplanktonic toxicity in the okadaic acid-producing dinoflagellate Prorocentrum lima

Prorocentrum lima is a dinoflagellate that forms hazardous blooms and produces okadaic acid (OA), leading to adverse environmental consequences associated with the declines of zooplankton populations. However, little is known about the toxic effects and molecular mechanisms of P. lima or OA on zooplankton. Here, their toxic effects were investigated using the brine shrimp Artemia salina. Acute exposure of A. salina to P. lima resulted in lethality at concentrations 100-fold lower than densities observed during blooms. The first comprehensive results from global transcriptomic and metabolomic analyses in A. salina showed up-regulated mRNA expression of antioxidant enzymes and reduced non-enzyme antioxidants, indicating general detoxification responses to oxidative stress after exposure to P. lima. The significantly up-regulated mRNA expression of proteasome, spliceosome, and ribosome, as well as the increased fatty acid oxidation and oxidative phosphorylation suggested the proteolysis of damaged proteins and induction of energy expenditure. Exposure to OA increased catabolism of chitin, which may further disrupt the molting and reproduction activities of A. salina. Our data shed new insights on the molecular responses and toxicity mechanisms of A. salina to P. lima or OA. The simple zooplankton model integrated with omic methods provides a sensitive assessment approach for studying hazardous algae.

Effects of crustacean hyperglycaemic hormone RNA interference on regulation of glucose metabolism in Litopenaeus vannamei after ammonia-nitrogen exposure

To unveil the adaptation of Litopenaeus vannamei to elevated ambient ammonia-N, crustacean hyperglycaemic hormone (CHH) was knocked down to investigate its function in glucose metabolism pathway under ammonia-N exposure. When CHH was silenced, haemolymph glucose increased significantly during 3-6 h, decreased significantly during 12-48 h and recovered to the control groups' level at 72 h. After CHH knock-down, dopamine (DA) contents reduced significantly during 3-24 h, which recovered after 48 h. Besides, the expressions of guanylyl cyclase (GC) and DA1R in the hepatopancreas decreased significantly, while DA4R increased significantly. Correspondingly, the contents of cyclic AMP (cAMP), cyclic GMP (cGMP) and diacylglycerol (DAG) and the expressions of protein kinase A (PKA), protein kinase G (PKG), AMP active protein kinase α (AMPKα) and AMPKγ were significantly down-regulated, while the levels of protein kinase C (PKC) and AMPKβ were significantly up-regulated. The expressions of cyclic AMP response element-binding protein (CREB) and GLUT2 decreased significantly, while GLUT1 increased significantly. Moreover, glycogen content, glycogen synthase and glycogen phosphorylase activities in hepatopancreas and muscle were significantly increased. Furthermore, the levels of key enzymes hexokinase, pyruvate kinase and phosphofructokinase in glycolysis (GLY), rate-limiting enzymes citrate synthase in tricarboxylic acid and critical enzymes phosphoenolpyruvate carboxykinase, fructose diphosphate and glucose-6-phosphatase in gluconeogenesis (GNG) were significantly decreased in hepatopancreas. These results suggest that CHH affects DA and then they affect their receptors to transmit glucose metabolism signals into the hepatopancreas of L. vannamei under ammonia-N stress. CHH acts on the cGMP-PKG-AMPKα-CREB pathway through GC, and CHH affects DA to influence cAMP-PKA-AMPKγ-CREB and DAG-PKC-AMPKβ-CREB pathways, thereby regulating GLUT, inhibiting glycogen metabolism and promoting GLY and GNG. This study contributes to further understand glucose metabolism mechanism of crustacean in response to environmental stress.

Martial Arts Routine Training Method Based on Artificial Intelligence and Big Data of Lactate Measurement

As a traditional Chinese sport, competitive martial arts routines have a long history. The competition rules are the unified norms and standards formulated for sports competitions. They are a yardstick for referees to judge the technical level and competitive ability of athletes and an essential basis for coaches during training. In particular, the new rules increase the difficulty of martial arts routines training and score, improve the balance movement of various groups, highlight the action specifications, increase the proportion of the score, and strengthen the scoring measures for the performance level. Subsequently, this puts higher requirements for the exceptional technical level of routine athletes. Therefore, it is vital to formulate scientific martial arts systematic training methods. This paper considers the above problem and current popular artificial intelligence technology and constructs a neural network algorithm to solve it. In addition, since lactic acid is a good monitoring indicator of the training load intensity and effect of martial arts routine exercises, this article also considers extensive lactate measurement data to construct martial arts systematic training methods. Through simulations, our experimental verification and the obtained results demonstrate the effectiveness of the proposed algorithm.

Integrated transcriptomics and metabolomics analyses reveal benzo[a]pyrene enhances the toxicity of mercury to the Manila clam, Ruditapes philippinarum

Mercury (Hg²⁺) and benzo[a]pyrene (BaP) are ubiquitous and persistent pollutants with multiple toxicities in bivalve molluscs. Here, the toxicological responses in the gills of Manila clams, Ruditapes philippinarum, to Hg²⁺ (10 μg L^-1), BaP (3 μg L^-1), and their mixture were analysed using transcriptomics and metabolomics approaches. Comparisons of the transcriptomes and metabolomes of Hg²⁺-and/or BaP-treated clams with control animals revealed the involvement of the detoxification metabolism, immune defence, energy-related pathways, and osmotic regulation in the stress response of R. philippinarum. Exposure to Hg²⁺ alone primarily enhanced the detoxification and energy metabolic pathways by significantly increasing the expression of genes associated with heat-shock proteins and oxidative phosphorylation. However, co-exposure to Hg²⁺ and BaP caused greater immunotoxicity and disrupted detoxification metabolism, the TCA cycle, glycolysis, and ATP generation. The expression levels of cytochrome P450 1A1 (CYP1A1), multidrug resistance-associated protein 1 (MRP1), and myosin (MYO), and the activity of electron transport system (ETS) in gills were detected, supporting the underlying toxic mechanisms of Hg²⁺ and BaP. We suggest that the presence of BaP enhances the toxicity of Hg²⁺ by 1) hampering the detoxification of Hg²⁺, 2) increasing the immunotoxicity of Hg²⁺, and 3) constraining energy availability for clams.

Effects of acute ammonia exposure on antioxidant and detoxification metabolism in clam Cyclina sinensis

To investigate the defensive strategies of clam Cyclina sinensis in response to environmental ammonia exposure, we investigate the 96 h median lethal concentration (LC₅₀-96 h) and the 96 h safe concentration (SC) of total ammonia nitrogen (TAN) for C. sinensis, and on the basis we examined glutamine synthetase (GS) activity, glutamine content, urea content and the antioxidant enzyme activities of super oxide dismutase (SOD) and catalase (CAT) in 96 h at three different levels of TAN as 0 (control), 73.94 (T1) and 227.04 mg/L (T2). Results showed that LC₅₀-96 h and SC for C. sinensis were 65.79 and 6.58 mg/L, respectively. The LC₅₀-96 h and SC of NH₃ were 1.70 and 0.17 mg/L, respectively. Ammonia exposure had significantly effects on SOD and CAT activities in the hepatopancreas tissue. Both the level of SOD activity and CAT activity increased with increasing concentration of TAN. No significant differences between T1 and T2 were found in GS activity from 3 h to 96 h after exposed to ammonia, whereas they were significantly higher than those in the control. Both the level of glutamine content in T1 and T2 increased significantly from 6 h to 24 h after exposed to ammonia and they were significantly higher than those in the control. There were no significantly differences were found in the level of urea concentration between T1 and T2 from 6 h to 96 h, while they were significantly higher those in the control. In conclusion, enhancing hepatopancreas antioxidant responses as well as converting ammonia into glutamine and urea worked in combination to allow C. sinensi to defend against acute ammonia exposure.

Metabolic responses of whiteleg shrimp to white spot syndrome virus (WSSV)

Outbreaks of white spot syndrome virus (WSSV) have caused serious damage to penaeid shrimp aquaculture worldwide. Despite great efforts to characterize the virus, the conditions that lead to infection and the infection mechanisms, there is still a lack of understanding regarding these complex virus-host interactions, which is needed to develop consistent and effective treatment methods for WSSV. In this study, we used a gas chromatography - mass spectrometry (GC-MS)-based metabolomics approach to compare the metabolite profiles of gills, haemolymph and hepatopancreas from whiteleg shrimp (Penaeus vannamei) exposed to WSSV and corresponding controls. The results revealed clear discriminations between metabolite profiles of WSSV-challenged shrimp and controlled shrimp in each tissue. The responses of shrimp gills to WSSV infection were characterized by increases of many fatty acids and amino acids in WSSV-challenged shrimp compared to the controls. Changes in haemolymph metabolite profiles include the increased levels of itaconic acid, energy-related metabolites, metabolites in glutathione cycle and decrease of amino acids. The WSSV challenge led to the decreases of several fatty acids and amino acids and increases of other amino acids, lactic acid and other organic compounds (levulinic acid, malonic acid and putrescine) in hepatopancreas. These alterations of shrimp metabolites suggest several immune responses of shrimp to WSSV in a tissue-specific manner, including upregulation of osmoregulation, antimicrobial activity, metabolic rate, gluconeogenesis, glutathione pathway in control of oxidative stress and shift from aerobic to anaerobic metabolism in shrimp which indicates the Warburg effect. The findings from this study provide a better understanding of molecular process of shrimp response against WSSV invasion which may be useful for development of disease management strategies.

Integrated analysis of transcriptomic and metabolomic data to evaluate responses to hypersalinity stress in the gill of the razor clam (Sinonovacula constricta)

Salinity is an important ecological factor that affects physiological metabolism, survival, and distribution of marine organisms. Despite changes in the osmolarity and composition of the cytosol during salinity shifts, marine mollusks are able to maintain their metabolic function. The razor clam (Sinonovacula constricta) survives the wide range of salinity in the intertidal zone via changes in behavior and physiology. To explore the stress responses and mechanisms of salinity tolerance in razor clams, we collected transcriptomic and metabolomic data from a control group (salinity 20‰, S20) and a salinity-stress group (salinity 35‰, S35). The transcriptome data showed that genes related to the immune system, cytoskeleton remodeling, and signal transduction pathways dominated in the S35 group to counteract hypersalinity stress in the gill. The metabolomic analysis showed that 142 metabolites were significantly different between the S35 and S20 groups and that amino acid and carbohydrate metabolism were affected by hypersalinity stress. Levels of amino acids and energy substances, such as l-proline, isoleucine, and fructose, were higher in the gill of the S35 group. The combination of transcriptomic and metabolomic data indicated that metabolism of amino acids, carbohydrates, and lipids was enhanced in the gill during adaptation to high salinity. These results clarified the complex physiological processes involved in the response to hyperosmotic stress and maintenance of metabolism in the gill of razor clams. These findings provide a reference for further study of the biological responses of euryhaline shellfish to hyperosmotic stress and a molecular basis for the search for populations with high salinity tolerance.

Comparative transcriptome reveals the response of oriental river prawn (Macrobrachium nipponense) to sulfide toxicity at molecular level

Aquatic environmental pollutants have various impacts on aquaculture. Specifically, sulfide has been established as being toxic to aquatic animals including the oriental river prawn Macrobrachium nipponense. In response, the hepatopancreas has been broadly studied, as it plays a pivotal role in arthropod nutrient digestion and absorption, energy supply, and organ development as well as in crustacean immunity. However, the underlying molecular mechanisms of hepatopancreas's response to sulfide toxicity are still poorly understand. Herein, we used Nova-seq 6000 platform to conduct a comparative transcriptome analysis of gene expression profiles in the hepatopancreas of M. nipponense, while it was under the influence of a semi-lethal sulfide concentration (3.20 mg/L at 48 h). A total of 139 million raw reads were obtained, in which 67,602 transcripts were clustered into 37,041 unigenes for further analysis. After constant sulfide exposure for 48 h, 235 differentially expressed genes, i.e., DEGs (151 up-regulated and 84 down-regulated) were identified in the sulfide treatment group (TGHP) compared with the control group (CGHP). We used GO and KEGG databases to annotate all the DEGs into 1180 functions and 123 pathways, respectively. The metabolic pathways included proximal tubule bicarbonate reclamation, sulfur metabolism, glycolysis and gluconeogenesis, and the TCA cycle; while immune-related pathways contained Ras, Rap1, focal adhesion and platelet activation. Additionally, apoptosis-involved pathways e.g., lysosome, also exhibited remarkable alteration in the presence of sulfide stress. Notably, responses to external stimuli and detoxification genes- such as GSKIP, CRT2, APOD, TRET1, CYP4C3 and HR39- were significantly altered by the sulfide stress, indicating that significant toxicity was transferred through energy metabolism, growth, osmoregulatory processes and immunity. Finally, we demonstrated that in the present of sulfide stress, M. nipponense altered the expression of detoxification- and extracellular stimulation-related genes, and displayed positive resistance via tight junction activation and lysosome pathways. The results of these novel experiments shed light on the hepatopancreas's molecular response to sulfide stress resistance and the corresponding adaptation mechanism; and enable us to identify several potential biomarkers for further studies.

Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades. Metabolomics, a functional readout of cellular activity, can capture organismal responses to various contaminant-related stressors, acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better. This review entails the application of metabolomics to profile metabolic responses of environmental organisms, e.g. animals (rodents, fish, crustacean and earthworms) and microorganisms (bacteria, yeast and microalgae) to different anthropogenic contaminants, including heavy metals, nanomaterials, pesticides, pharmaceutical and personal products, persistent organic pollutants, and assesses their ecotoxicological impacts with regard to literature published in the recent five years. Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms. The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms. Thus with a novel ecotechnique of environmental metabolomics, risk assessments of anthropogenic contaminants are profoundly demonstrated.

Hepatopancreatic metabolomics shedding light on the mechanism underlying unsynchronized growth in giant freshwater prawn, Macrobrachium rosenbergii

The giant freshwater prawn, Macrobrachium rosenbergii (M. rosenbergii) as an important freshwater aquaculture species with high commercial value, exhibited unsynchronized growth. However, the potentially metabolic mechanism remains unclear. In this study, we used liquid chromatography tandem mass spectrometry (LC-MS/MS) to investigate the hepatopancreatic metabolic profiles of twenty giant freshwater prawns between the fast-growing group and slow-growing group. In the metabolomics assay, we isolated 8,293 peaks in positive and negative iron mode. Subsequently, 44 significantly differential metabolites were identified. Functional pathway analysis revealed that these metabolites were significantly enriched in three key metabolic pathways. Further integrated analysis indicated that glycerophospholipid metabolism and aminoacyl-tRNA biosynthesis have significant impact on growth performance in M.rosenbergii. Our findings presented here demonstrated the critical metabolites and metabolic pathways involved in growth performance, moreover provided strong evidence for elucidating the potentially metabolic mechanism of the unsynchronized growth in M. rosenbergii.

Mourilyan virus pathogenicity in kuruma shrimp (Penaeus japonicus)

The bunyavirus Mourilyan virus (MoV) occurs commonly in Black tiger (Penaeus monodon) and kuruma shrimp (Penaeus japonicus) farmed in eastern Australia. There is circumstantial evidence of MoV causing mortalities among P. japonicus moved from farm ponds to tanks for rearing as broodstock. To directly assess its pathogenic potential, independent cohorts of pond- (n = 24) or tank-reared juvenile (n = 21) P. japonicus were challenged intramuscularly with a cephalothorax tissue homogenate of P. monodon containing high loads of MoV (1.48 ± 0.28 × 10⁸ MoV RNA copies/µg total RNA). In each trial, mortalities accumulated gradually among the saline-injected controls. Mortality onset occurred 12-14 days earlier in the pond-reared shrimp, possibly due to them possessing low-level pre-existing MoV infections. Despite the time to onset of mortality differing, Kaplan-Meier survival analyses confirmed mortality rates to be significantly higher in both the pond- (p = .017) and tank-reared shrimp (p = .031) challenged with MoV. RT-qPCR data on shrimp sampled progressively over each trial showed high loads of MoV to establish following challenge and discounted GAV and other endemic viruses from contributing to mortality. Together, the data show that acute MoV infection can adversely compromise the survival of juvenile P. japonicus.

Low Dietary Fish Meal Induced Endoplasmic Reticulum Stress and Impaired Phospholipids Metabolism in Juvenile Pacific White Shrimp, Litopenaeus vannamei

This study mainly evaluated the low dietary fish-meal (FM) on growth performance, immune competence and metabolomics response of juvenile Pacific white shrimp, Litopenaeus vannamei reared at low salinity (7‰). Five experimental diets with graded levels (25, 20, 15, 10, and 5%) of FM were formulated. Weight gain, feed utilization and survival were decreased with the decreasing FM levels. When dietary FM decreased, glucose, cholesterol, total bile acids, and triglyceride in hemolymph decreased. Fatty acid synthesis was promoted and fatty acid lipolysis was reduced in hepatopancreas of shrimp fed low dietary FM. Endoplasmic reticulum (ER) stress related genes expression in hepatopancreas were down-regulated and in intestine were upregulated by low dietary FM. Inhibitor kappa B kinaseβ expression in intestine increased with the dietary FM levels, while mRNA levels of dorsal in hepatopancreas showed the opposite tendency. Hematoxylin and eosin (H&E) stain and transmission electron microscope analysis of intestinal samples indicated that low FM diets induced intestinal morphological damage, ER swollen and chromatin condensation. UPLC-Q/TOF-MS analysis indicated that degree of unsaturation of the fatty acid chains of phospholipids in hemolymph decreased with the decreasing dietary FM levels. Lysophospholipids and bile acids metabolism were disturbed by high levels of FM sparing in diet. These results indicated when dietary FM contents decreased, ER stress of shrimp was induced. The decreased unsaturated degree of phospholipids, decreased contents of lysophospholipids, altered lipid metabolism and ER stress may responsible for the impaired growth performance and health of shrimp fed a low FM diet.

Metabolomic profiling of goslings with visceral gout reveals a distinct metabolic signature

1.The objective of the experiment was to analyse serum profiles of goslings with visceral gout and compare them with those of healthy individuals to identify differentially-abundant metabolites as potential biomarkers. 2.Untargeted gas chromatography and time-of-flight mass spectrometry (GC-TOF-MS) metabolomic profiling was used to compare the serum metabolome of 15 goslings (Anser cygnoides) with gout and 15 healthy goslings (control). 3.Goslings with gout had a metabolic profile distinct from that of the controls, with 45 metabolite levels differing significantly (VIP > 1; P < 0.05) between both groups. Nine metabolites (hydrocortisone, glucose, trans-4-hydroxy-L-proline, galactose, 2-deoxy-D-galactose, beta-mannosylglycerate, d-glucoheptose, zymosterol, and hypoxanthine) were selected through receiver operating characteristics (ROC) analysis (area under curve (AUC) score ≥0.85) as potential biomarkers. Pathway analysis revealed that metabolites with differing levels were mainly involved in galactose, arginine and proline and purine metabolisms. 4.These results provided new insights into the pathogenesis of gout. Increased xanthine and hypoxanthine with decreased hydrocortisone provide promising biomarkers for gosling gout diagnosis. The findings suggested that hepatic metabolic disorders frequently occur in the development of avian gout.

Vibrio harveyi Infection Significantly Alters Amino Acid and Carbohydrate Metabolism in Whiteleg Shrimp, Litopenaeus vannamei

Vibrio harveyi is one of the pathogens that threaten the shrimp farming industry. However, metabolic changes induced by V. harveyi infection in shrimp remain unknown. In this study, we first conducted high resolution-magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR)-based metabolomics studies on gill, hepatopancreas, and haemolymph of V. harveyi-infected white leg shrimp, Litopenaeus vannamei. Using multivariate statistical analysis, we observed a clear separation between the early (3 and 9 h post-injection (hpi)) and late phases (24, 72 and 144 hpi) of the infection in all tissues. Moreover, metabolic changes in response to V. harveyi infection were faster in the haemolymph in the early phase and significantly changed in the late phase of the infection in the gills. Extensive changes were observed in the hepatopancreas, with 24 hpi being the turning point of progression from early to late phase infection in the hepatopancreas. V. harveyi infection increased the energy demand in L. vannamei and the amino acid and carbohydrate metabolism pathways also exhibited significant changes depending on the tissue. Thus, each tissue displayed different metabolic changes, depending on the progress of the infection.

iTRAQ-based quantitative proteomics analysis of cantaloupe (Cucumis melo var. saccharinus) after cold storage

Background

Cantaloupe is susceptible to cold stress when it is stored at low temperatures, resulting in the loss of edible and commercial quality. To ascertain the molecular mechanisms of low temperatures resistance in cantaloupe, a cold-sensitive cultivar, Golden Empress-308 (GE) and a cold-tolerant cultivar, Jia Shi-310 (JS), were selected in parallel for iTRAQ quantitative proteomic analysis.

Results

The two kinds of commercial cultivars were exposed to a temperature of 0.5 °C for 0, 12 and 24 days. We found that the cold-sensitive cultivar (GE) suffered more severe damage as the length of the cold treatment increased. Proteomic analysis of both cultivars indicated that the number of differentially expressed proteins (DEPs) changed remarkably during the chilly treatment. JS expressed cold-responsive proteins more rapidly and mobilized more groups of proteins than GE. Furthermore, metabolic analysis revealed that more amino acids were up-regulated in JS during the early phases of low temperatures stress. The DEPs we found were mainly related to carbohydrate and energy metabolism, structural proteins, reactive oxygen species scavenging, amino acids metabolism and signal transduction. The consequences of phenotype assays, metabolic analysis and q-PCR validation confirm the findings of the iTRAQ analysis.

Conclusion

We found that the prompt response and mobilization of proteins in JS allowed it to maintain a higher level of cold tolerance than GE, and that the slower cold responses in GE may be a vital reason for the severe chilling injury commonly found in this cultivar. The candidate proteins we identified will form the basis of future studies and may improve our understanding of the mechanisms of cold tolerance in cantaloupe.

Integrated analysis of physiological, transcriptomic and metabolomic responses and tolerance mechanism of nitrite exposure in Litopenaeus vannamei

Nitrite accumulation in aquatic environments is a potential risk factor that disrupts multiple physiological functions in aquatic animals. In this study, the physiology, transcriptome and metabolome of the control group (LV-C), nitrite-tolerance group (LV-NT) and nitrite-sensitive group (LV-NS) were investigated to identify the stress responses and mechanisms underlying the nitrite tolerance of Litopenaeus vannamei. After LV-NT and LV-NS were subjected to nitrite stress, the hemocyanin contents were significantly decreased, and hepatopancreas showed severe histological damage compared with LV-C. Likewise, the antioxidant enzymes were also significantly changed after nitrite exposure. The transcriptome data revealed differentially expressed genes associated with immune system, cytoskeleton remodeling and apoptosis in LV-NT and LV-NS. The combination of transcriptomic and metabolomic analysis revealed nitrite exposure disturbed metabolism processes in L. vannamei, including amino acid metabolism, nucleotide metabolism and lipid metabolism. The multiple comparative analysis implicated that higher nitrite tolerance of LV-NT than LV-NS may be attributed to enhanced hypoxia inducible factor-1α expression to regulate energy supply and gaseous exchange. Moreover, LV-NT showed higher antioxidative ability, detoxification gene expression and enhanced fatty acids contents after nitrite exposure in relative to LV-NS. Collectively, all these results will greatly provide new insights into the molecular mechanisms underlying the stress responses and tolerance of nitrite exposure in L. vannamei.

Sub-lethal effects of calcium dinonylnaphthalenesulfonate on Western clawed frog embryos

Naphthalene sulfonic acids (NSAs) are used as additives in lubricants, dyes, and greases and commonly act as surfactants in many industrial processes. The calcium salt of dinonyl NSA (calcium dinonylnaphthalenesulfonate; CaDNS) is listed among thousands of chemicals identified as priorities for assessment by the Government of Canada's Chemical Management Plan due to the limited toxicity data. The purpose of this study was two-fold: 1) to establish the toxicity of CaDNS to Western clawed frog (Silurana tropicalis) embryos and 2) to assess the sub-lethal effects and mechanisms of toxicity of CaDNS in amphibians through targeted gene expression and metabolite analyses. Frog embryos were exposed to water overlying sand spiked with a range of concentrations of CaDNS (17-1393 μg/g) over a 72-h period. Results indicated significantly higher mortality and presence of malformations in frog larvae exposed to over 672 μg/g CaDNS in the sand (14 ng/mL CaDNS in the water) compared to control treatments. An overall decrease in the glutathione redox cycle was observed, including decreases in relative mRNA levels of enzymes (glutathione S-transferase (gst), glutathione reductase (gsr), glutathione peroxidase (gpx)) and decreases in the glutathione (GSH) and glutathione disulfide (GSSG) metabolite concentrations. In addition, transcript levels of genes involved in antioxidant capacity and essential amino acid metabolites decreased significantly in embryos exposed to low levels of CaDNS. This is the first study to assess the toxicity of NSAs in amphibians, contributing important data to aid in the assessment of NSAs.

The effect of nitrite and sulfide on the antioxidant capacity and microbial composition of the intestines of red swamp crayfish, Procambarus clarkii

Nitrite and sulfide are harmful pollutants in water ecosystems that negatively influence the survival and growth of crayfish. It is currently known that the intestine of crustaceans acts as a significant immune organ, serving as the front line of defense against diseases. In this study, we investigated how the oxidative damage parameters, antioxidant status and microbial composition of the intestine of Procambarus clarkii were influenced under acute nitrite (60 mg/L) and sulfide (18 mg/L) stress for 72 h. Compared with the control, after exposure to nitrite and sulfide stress, the production of reactive oxygen species, and the lipid peroxide and malondialdehyde contents increased in the intestines and were significantly higher after 72 h of exposure. The superoxide dismutase, catalase and glutathione peroxidase activities increased to maximum levels at 6, 24 and 12 h, respectively. These activities then decreased gradually and were significantly lower than those of the control after 48 or 72 h of exposure. In the crayfish exposed to stress, the expression of antioxidant genes including heat shock protein 70, ferritin and metallothionein increased to their maximum values at 12, 48 and 12 h, respectively. The expression levels then decreased gradually, and after 72 h, were lower than, or lacked significant differences with, the expression levels in the control. Additionally, nitrite and sulfide exposure restructured the intestinal microbial community of P. clarkii. This led to decreases in the abundance of some genera such as Citrobacter. However, the abundance of other genera, such as Shewanella and Acinetobacter, increased. Therefore, the health of P. clarkii was seriously impaired when exposed to nitrite and sulfide stress.

Stress response and tolerance mechanisms of ammonia exposure based on transcriptomics and metabolomics in Litopenaeus vannamei

Ammonia, one of the major limiting environment factors in aquaculture, may pose a threat to the shrimp growth, reproduction and survival. In this study, to understand molecular differences of transcriptomic and metabolomic responses and investigate the tolerance mechanisms underlying ammonia stress in Litopenaeus vannamei, ammonia-tolerant family (LV-AT) and ammonia-sensitive family (LV-AS) of these two extreme families were exposed to high-concentration (NH₄Cl, 46 mg/L) ammonia for 24 h. The comparative transcriptome analysis between ammonia-treated and control (LV-C) groups revealed involvement of immune defense, cytoskeleton remodeling, antioxidative system and metabolic pathway in ammonia-stress response of L. vannamei. Likewise, metabolomics analysis showed that ammonia exposure could disturb amino acid metabolism, nucleotide metabolism and lipid metabolism, with metabolism related-genes changed according to RNA-seq analysis. The comparison of metabolite and transcript profiles between LV-AT and LV-AS indicated that LV-AT used the enhanced glycolysis and tricarboxylic acid (TCA) cycle strategies for energy supply and ammonia excretion to adapt high-concentration ammonia. Furthermore, some of genes involved in the detoxification and ammonia excretion were highly expressed in LV-AT. We speculate that the higher ability of ammonia excretion and detoxification and the accelerated energy metabolism for energy supplies might be the adaptive strategies for LV-AT relative to LV-AS after ammonia stress. Collectively, the combination of transcriptomics and metabolomics results will greatly contribute to incrementally understand the stress responses on ammonia exposure to L. vannamei and supply molecular level support for evaluating the environmental effects of ammonia on aquatic organisms. The results further constitute new sights on the potential molecular mechanisms of ammonia adaptive strategies in shrimps at the transcriptomics and metabolomics levels.

Individual and combined effects of ammonia-N and sulfide on the immune function and intestinal microbiota of Pacific white shrimp Litopenaeus vannamei

In this study, we explored the individual and combined effects of ammonia-N and sulfide stress (1 mg/L sulfide and 15 mg/L ammonia-N) on the oxidation resistance, immune response and intestinal health of Litopenaeus vannamei during 72 h exposure. The total antioxidant capacity (T-AOC), malonaldehyde (MDA) and nitric oxide (NO) content, superoxide dismutase (SOD) and catalase activity (CAT), the immune-relative gene (caspase-3, hsp70 and IMD) expression in hepatopancreas and intestine of L.vannamei and the intestinal microbiota were measured. The result showed that MDA and NO contents in hepatopancreas of L. vannamei in all treatment groups increased and remain were at high levels at the end of the stress exposure. The L. vannamei employ antioxidant defense system by increasing the activities of T-AOC, SOD and CAT enzymes in hepatopancereas and intestine to reduce oxidant damage. More severe damages with combined ammonia-N and sulfide stress to antioxidant systems were observed. The gene expression results also demonstrated that antioxidant capacity of L. vannamei was severely impaired and the apoptosis cell was initiated under the ammonia-N and sulfide stress. In addition, the environmental stress also reshaped the intestinal microbial community structure of L. vannamei that a number of original genera decreased, such as Cellvibrio, Vibrio and Rheinheimera; some new genera increased or appeared, such as Photobacterium in all treatment groups, Arcobacter and Fusibacter in sulfide stress group. Therefore, the health of L. vannamei was severely impacted when exposed to the stress of ammonia nitrogen and sulfide and these two factors can have weak synergic effects.

Toxicity of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) in the marine decapod Litopenaeus vannamei

DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) is the main component of SeaNine-211, a new antifouling agent that replaces tributyltin to prevent the growth of undesirable organisms on ships. There have been some studies on the toxicity of DCOIT, but the mechanism of DCOIT's toxicity to crustaceans still requires elucidation. This study examined the chronic toxicity (4 weeks) of 0, 3, 15, and 30 μg/L DCOIT to the Pacific white shrimp (Litopenaeus vannamei) from the aspects of growth and physiological and histological changes in the hepatopancreas and gills. A transcriptomic analysis was performed on the hepatopancreas to reveal the underlying mechanism of DCOIT in shrimp. The exposure to 30 μg/L DCOIT significantly reduced the survival and weight gain of L. vannamei. High Na⁺/K⁺-ATPase activity and melanin deposition were found in the gills after 4 weeks of 15 μg/L or 30 μg/L DCOIT exposure. The highest concentration of DCOIT (30 μg/L) induced changes in hepatopancreatic morphology and metabolism, including high anaerobic respiration and the accumulation of triglycerides. Compared with the exposure to 3 μg/L DCOIT, shrimp exposed to 15 μg/L DCOIT showed more differentially expressed genes (DEGs) than those in the control, and these DEGs were involved in biological processes such as starch and sucrose metabolism and choline metabolism in cancer. The findings of this study indicate that L. vannamei is sensitive to the antifouling agent DCOIT and that DCOIT can induce altered gene expression at a concentration of 15 μg/L and can interfere with shrimp metabolism, growth and survival at 30 μg/L.

Transcriptomic and microbiota response on Litopenaeus vannamei intestine subjected to acute sulfide exposure

Harmful effects of water pollutants are myriad. Sulfide from water bodies affects the aquatic animals. Intestine barrier function serves as the front-line of animals defense. Our previous study confirmed the toxic effect of sulfide on intestine immune response of Litopenaeus vannamei, but the underlying mechanisms remained elusive. Therefore, in this study, we investigated the transcriptomic and microbiota responses of the L. vannamei intestine subjected to acute sulfide exposure. Sulfide decreased bacterial richness and altered the intestine microbiota composition. Specifically, sulfide increased the abundances of Bacteroidetes and Actinobacteria, but decreased the abundance of Proteobacteria. At the genus level, sulfide increased typical cellulolytic characteristics bacteria, such as Formosa, Sphingomonas, and Demequina. RNA-seq analysis identified differential expression of 1799 genes (701 up-regulated and 1098 down-regulated) were grouped into 267 pathways. The most enriched pathway 'amoebiasis' was related to the intestine mucus homeostasis. A number of immune-related genes associated with antimicrobial, antioxidant, pathogen attachment and recognition, and apoptosis processes in contrasting accessions; they were correlated with the abundance of intestine bacterial at the phylum level. This study provides an insight into the mechanisms associated with molecular and microbiota response and processes involved in adaptation strategies towards sulfide stress.

Response to different dietary carbohydrate and protein levels of pearl oysters (Pinctada fucata martensii) as revealed by GC-TOF/MS-based metabolomics

Land-based culturing can avoid the effects of environmental pollution and natural disasters, thus ensuring food safety for shellfish. However, food availability, in this case, is limited. To achieve the optimum balance of dietary carbohydrates and proteins and explore the mechanisms behind the phenomenon, we formulated five isoenergetic and isolipidic diets (C30P40, C35P35, C40P30, C45P25, and C50P20) with different levels of carbohydrates (C) and proteins (P). There were five experimental groups (C30P40, C35P35, C40P30, C45P25, and C50P20) and two control groups (CG1 and CG2). CG1 was fed with mixed powders of yeast and Chlorella sp., and CG2 was cultured in natural sea. After 60-day feeding, the highest rates of survival and absolute growth appeared in C45P25. C45P25 exhibited significantly higher activities of amylase, protease, alkaline phosphatase, acid phosphatase, superoxide dismutase, catalase, glutathione peroxidase, and phenoloxidase and significantly lower malondialdehyde content than C30P40, C35P35, C40P30, C50P20, and CG1. No significant differences were observed between C45P25 and CG2. Furthermore, the total antioxidant capacity of the pearl oysters in C45P25 was significantly higher than that in C30P40, C35P35, C40P30, and C50P20. On the basis of these results, the optimal balance of proteins and carbohydrates for pearl oysters was the C45P25 diet. Metabolomics-based profiling of the pearl oysters fed with high-carbohydrate/low-protein diet (C45P25) and low-carbohydrate/high-protein diet (C30P40) revealed 80 significantly different metabolites (VIP > 1 and P < 0.05). Furthermore, integrated key metabolic pathway analysis showed that C45P25 regulated starch and sucrose metabolism, alanine, aspartate and glutamate metabolism and glycine, serine and threonine metabolism to meet the energy demand and increase the glucogenic amino acid, thereby promoting protein synthesis and reducing fatty acid β-oxidation in comparison with C30P40. This finding helps elucidate the underlying mechanisms leading to the high-carbohydrate/low-protein diet characteristic of the optimal dietary carbohydrate and protein levels of P. f. martensii.

Integrated metabolomic and transcriptomic analysis of brain energy metabolism in the male Oriental river prawn (Macrobrachium nipponense) in response to hypoxia and reoxygenation

Hypoxia is as an endocrine disruptor, and, in crustaceans, the energy metabolic consequences of hypoxia in the brain tissue are still poorly understood. We combined gas chromatography-mass spectrometry (GC-MS)-based metabolomic analysis and high-throughput RNA sequencing to evaluate the metabolic effects and subjacent regulatory pathways in the brain tissue of the male Oriental river prawn (Macrobrachium nipponense) in response to hypoxia and reoxygenation. We recorded LC₅₀ and heartbeats per minute of male M. nipponense juveniles. Hypoxia resulted in the generation of reactive oxygen species in the brain cells and alterations in gene expression and metabolite concentrations in the prawn brain tissue in a time-dependent manner. The transcriptomic analyses revealed specific changes in the expression of genes associated with metabolism pathways, which was consistent with the changes in energy metabolism indicated by the GC-MS metabolomic analysis. Quantitative real-time polymerase chain reaction and western blot confirmed the transcriptional induction of these genes because of hypoxia. The lactate levels increased significantly during hypoxia and decreased to normal after reoxygenation; this is consistent with a shift towards anaerobic metabolism, which may cause metabolic abnormalities in the brain tissue of M. nipponense. Overall, these results are consistent with metabolic disruption in the brain of M. nipponense exposed to hypoxia and will help in understanding how crustacean brain tissue adapts and responds to hypoxia and reoxygenation.

Physiological and immune response in the gills of Litopenaeus vannamei exposed to acute sulfide stress

Sulfide is a harmful environmental pollutant that affects the survival and immunity of shrimps. The gill is important for shrimp respiratory and osmotic adjustment, the physiological and immune homeostasis of the organ can be influenced by sulfide. In this study, we investigated the acute toxicity of sulfide (5 mg/L) on the morphology, physiological and immune response in the gills of Litopenaeus vannamei. H&E stain showed that sulfide stress damaged the gills histological structure. Specifically, osmoregulation capacity including of Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase activity was both increased at 6 h and 12 h, and decreased at 72 h; the contents of free amino acid including of Gly, Pro, Ser, Thr and Ala were decreased at 72 h. Respiratory metabolic enzymes, such as cytochrome c oxidase and succcinate dehydrogenase activity was decreased at 12 h-72 h, while fumarate reductase and lactate dehydrogenase activity kept a higher level at 12 h-72 h. Significant variations in the activities of immune enzymes (acid phosphatase, alkaline phosphatase, total antioxidant capacity and lysozyme). The expression of immune-related genes (heat shock protein 70, thioredoxin and caspase-3) was increased at first and then decreased, while hypoxia inducible factor 1α kept a higher level at 6 h-72 h. These results revealed that sulfide stress influenced the L. vannamei gills physiological and immune function by damaging histological structure, and confusing osmoregulation, respiratory metabolic and immune capacity.

The State of "Omics" Research for Farmed Penaeids: Advances in Research and Impediments to Industry Utilization

Elucidating the underlying genetic drivers of production traits in agricultural and aquaculture species is critical to efforts to maximize farming efficiency. "Omics" based methods (i.e., transcriptomics, genomics, proteomics, and metabolomics) are increasingly being applied to gain unprecedented insight into the biology of many aquaculture species. While the culture of penaeid shrimp has increased markedly, the industry continues to be impeded in many regards by disease, reproductive dysfunction, and a poor understanding of production traits. Extensive effort has been, and continues to be, applied to develop critical genomic resources for many commercially important penaeids. However, the industry application of these genomic resources, and the translation of the knowledge derived from "omics" studies has not yet been completely realized. Integration between the multiple "omics" resources now available (i.e., genome assemblies, transcriptomes, linkage maps, optical maps, and proteomes) will prove critical to unlocking the full utility of these otherwise independently developed and isolated resources. Furthermore, emerging "omics" based techniques are now available to address longstanding issues with completing keystone genome assemblies (e.g., through long-read sequencing), and can provide cost-effective industrial scale genotyping tools (e.g., through low density SNP chips and genotype-by-sequencing) to undertake advanced selective breeding programs (i.e., genomic selection) and powerful genome-wide association studies. In particular, this review highlights the status, utility and suggested path forward for continued development, and improved use of "omics" resources in penaeid aquaculture.

Based on the Metabolomic Approach the Energy Metabolism Responses of Oriental River Prawn Macrobrachium nipponense Hepatopancreas to Acute Hypoxia and Reoxygenation

Hypoxia represents a major physiological challenge for prawns and is a problem in aquaculture. Therefore, an understanding of the metabolic response mechanism of economically important prawn species to hypoxia and re-oxygenation is essential. However, little is known about the intrinsic mechanisms by which the oriental river prawn Macrobrachium nipponense copes with hypoxia at the metabolic level. In this study, we conducted gas chromatography-mass spectrometry-based metabolomics studies and assays of energy metabolism-related parameters to investigate the metabolic mechanisms in the hepatopancreas of M. nipponense in response to 2.0 O₂/L hypoxia for 6 and 24 h, and reoxygenation for 6 h following hypoxia for 24 h. Prawns under hypoxic stress displayed higher glycolysis-related enzyme activities and lower mRNA expression levels of aerobic respiratory enzymes than those in the normoxic control group, and those parameters returned to control levels in the reoxygenated group. Our results showed that hypoxia induced significant metabolomic alterations in the prawn hepatopancreas within 24 h. The main metabolic alterations were depletion of amino acids and 2-hydroxybutanoic acid and accumulation of lactate. Further, the findings indicated that hypoxia disturbed energy metabolism and induced antioxidant defense regulation in prawns. Surprisingly, recovery from hypoxia (i.e., reoxygenation) significantly affected 25 metabolites. Some amino acids (valine, leucine, isoleucine, lysine, glutamate, and methionine) were markedly decreased compared to the control group, suggesting that increased degradation of amino acids occurred to provide energy in prawns at reoxygenation conditions. This study describes the acute metabolomic alterations that occur in prawns in response to hypoxia and demonstrates the potential of the altered metabolites as biomarkers of hypoxia.

Design and Functionalization of the NIR-Responsive Photothermal Semiconductor Nanomaterials for Cancer Theranostics

Despite the development of medical technology, cancer still remains a great threat to the survival of people all over the world. Photothermal therapy (PTT) is a minimally invasive method for selective photothermal ablation of cancer cells without damages to normal cells. Recently, copper chalcogenide semiconductors have emerged as a promising photothermal agent attributed to strong absorbance in the near-infrared (NIR) region and high photothermal conversion efficiency. An earlier study witnessed a rapid increase in their development for cancer therapy, including CuS, Cu_2-xSe and CuTe nanocrystals. However, a barrier is that the minimum laser power intensity for effective PTT is still significantly higher than the conservative limit for human skin exposure. Improving the photothermal conversion efficiency and reducing the laser power density has become a direction for the development of PTT. Furthermore, in an effort to improve the therapeutic efficacy, many multimode therapeutic nanostuctures have been formulated by integrating the photothermal agents with antitumor drugs, photosensitizers, or radiosensitizers, resulting in a synergistic effect. Various functional materials also have been absorbed, attached, encapsulated, or coated on the photothermal nanostructures, including fluorescence, computed tomography, magnetic resonance imaging, realizing cancer diagnosis, tumor location, site-specific therapy, and evaluation of therapeutic responses via incorporation of diagnosis and treatment. In this Account, we present an overview of the NIR-responsive photothermal semiconductor nanomaterials for cancer theranostics with a focus on their design and functionalization based on our own work. Our group has developed a series of chalcogenides with greatly improved NIR photoabsorption as photothermal agents, allowing laser exposure within regulatory limits. We also investigated the photothermal bioapplications of hypotoxic oxides including WO_3-x, MoO_3-x, and RuO₂, expanding their applications into a new field of photothermal materials. Furthermore, considering a much more enhanced therapeutic effect of multifunctional nanoagents, our group elaborately designed many nanocomposites, such as core-shell nanoparticles of Fe₃O₄@Cu_2-xS and Cu₉S₅@mSiO₂, based on the integration of photothermal agents with contrast agents or other anticancer medicines, achieving cancer theranostic and synergistic treatment. Ternary compound nanocrystals were also prepared with synthetic simplicity for multimodal imaging-guided therapy for cancer. This Account summarizes our past work, including the design and concept, synthesis, and characterization for in vitro and in vivo applications. Then, we analyzed the tendencies of the NIR-responsive photothermal semiconductor nanomaterials for clinical applications, highlighting their prospects and challenges. We believe that the photothermal technology from the NIR-responsive photothermal semiconductor nanomaterials would promote cancer theranostics to result in giant strides forward in the future.