Insights into the response mechanism of Litopenaeus vannamei exposed to cold stress during live transport combining untargeted metabolomics and biochemical assays

Safety Assessment of Camelid-Derived Single-Domain Antibody as Feed Additive for Juvenile Whiteleg Shrimp (Litopenaeus vannamei) Against White Spot Syndrome Virus

A six-week feeding trial was conducted to assess the safety of single-domain antibodies (sdAbs) derived from camelids against the white spot syndrome virus (WSSV) (WSSVvp28 was used as the antigen), focusing on the whole-organism responses and molecular-level changes in juvenile whiteleg shrimp (Litopenaeus vannamei). Five experimental diets with varying levels of sdAbs were formulated: CON (no sdAb supplementation); SDA8.2 (8.20% of sdAbs); SDA16.4 (16.40% of sdAbs); SDA24.6 (24.60% of sdAbs); and SDA32.8 (32.80% of sdAbs). In the CON diet, 450 mL of water per kg of diet (45%) was used to form a feed dough, while sdAbs were used to replace the water in the treatment diets. A total of 450 shrimp, with an initial body weight of 3.27 ± 0.02 g (mean ± SEM), were randomly distributed in 15 tanks (30 shrimp per tank; three tanks per treatment). Each tank was filled with 30 L of seawater (77 L capacity) in an indoor semi-recirculating system with a constant water flow rate of 1.2 L min-1. The photoperiod was maintained at 12 h of light and 12 h of dark. The water temperature, pH, salinity, and dissolved oxygen were 27.3 ± 0.1 °C, 7.61 ± 0.01, 34 ± 1 ppt, and 5.94 ± 0.04 mg L-1, respectively. During the feeding trial, the shrimp were fed the experimental diet (40% protein and 11% lipid) three times a day for six weeks. Following the feeding trial, an acute cold-water-temperature stress test was conducted by abruptly exposing the shrimp from each treatment to 15 °C for 4 h, down from 27 °C. The results showed no significant differences in the growth performance (weight gain, feed utilization efficiency, survival, etc.), plasma metabolites (aspartate aminotransferase activity, alanine aminotransferase activity, total protein, and glucose), or antioxidant enzymes (superoxide dismutase and glutathione peroxidase) among all the experimental diets (p > 0.05). In the acute cold-temperature stress test, there was no significant interaction between sdAb supplementation and temperature stress, nor any main effect from either factor, except for the main effect of temperature stress on the glucose levels, which was significantly higher in shrimp exposed to cold-temperature stress (p < 0.05). The next-generation sequencing of differentially expressed genes (DEGs) in the hepatopancreases of shrimp fed the CON, SDA16.4, and SDA32.8 diets, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, indicated that DEGs were significantly enriched in signaling pathways associated with growth, cold stress, and antioxidant systems. Overall, the results from conventional measurements suggest that the use of sdAbs against the WSSV may be safe for juvenile whiteleg shrimp. However, findings from the sophisticated analysis indicate that further research is needed to understand the molecular mechanisms underlying the observed changes, and to evaluate the long-term effects of sdAb supplementation in shrimp diets.

Water-accommodated fractions of crude oil and its mixture with chemical dispersant impairs oxidase stress and energy metabolism disorders in Oryzias melastigma embryos

In this study, marine medaka (Oryzias melastigma) embryos were exposed to different concentrations of water-accommodated fractions (WAFs) and chemically enhanced water-accommodated fractions (CEWAFs) of Oman crude oil for 14 d by semi-static exposure methods. The effects on growth and development and energy metabolism process were evaluated. Results showed that embryo survival and hatchability were decreased in a dose-dependent manner with an increase in the concentration of petroleum hydrocarbon compounds, whereas the malformation exhibited a dose-dependent increase. Compared to the control, the adenosine triphosphate (ATP) content and Na+-K+-ATPase (NKA) activities of embryos exposed to both WAFs and CEWAFs were reduced, while intracellular reactive oxygen species (ROS) levels and NADH oxidase (NOX) activities were increased. Our study demonstrated that exposure to crude oil dispersed by chemical dispersant affected the growth and development of marine medaka embryos, caused oxidative stress while produced a series of malformations in the body and dysregulation in energy metabolism. In comparison, the toxic effects of chemically dispersed crude oil might be more severe than the oil itself in the equivalent diluted concentration treatment solution. These would provide more valuable and reliable reference data for the use of chemical dispersants in oil spills.

Transcriptome, histology, and enzyme activities analysis of liver in Phoxinus lagowskii to the low temperature stress and recovery

Assessing the response and resilience of fish to low temperatures over different time scales can provide valuable insights into their mechanisms of adaptation to cold conditions. Farmed Amur minnows (Phoxinus lagowskii) frequently encounter low temperatures, especially during winter. However, the specific responses of P. lagowskii to low-temperature stress remain largely unexplored. In this study, we examined serum glucose and cortisol levels, histological changes, enzymes associated with phosphate and carbohydrate metabolism, triglyceride levels, and liver transcriptomics under various conditions: control (CK), short-term cold exposure (6 days, SC), prolonged cold exposure (14 days, PC), and recovery (RY) from cold exposure at 2 °C. Liver vacuolation was observed during short-term cold exposure. Additionally, we analyzed the enzymatic activity related to carbohydrate and lipid metabolism in serum and liver. Liver transcriptomic data revealed that the PPAR signaling pathway and autophagy-related genes were enriched during short-term cold exposure. Carbohydrate metabolism-related pathways, including the AMPK and MAPK signaling pathways, were significantly enriched after prolonged cold exposure. Metabolic pathways such as fat digestion and absorption, glycine, serine, and threonine metabolism, and arginine and proline metabolism were significantly enriched in the recovery group. Rapid warming after prolonged cold stress allowed P. lagowskii to recover quickly. These findings suggest that P. lagowskii has a strong adaptive capacity for energy metabolism during prolonged cold exposure and the ability to recover rapidly from cold stress. A comprehensive examination of the histological, physiological, biochemical, and molecular responses of P. lagowskii to low temperatures is crucial for developing effective strategies for cultivating this species in challenging environments.

Biochemical indicators, cell apoptosis, and metabolomic analyses of the low-temperature stress response and cold tolerance mechanisms in Litopenaeus vannamei

The cold tolerance of Litopenaeus vannamei is important for breeding in specific areas. To explore the cold tolerance mechanism of L. vannamei, this study analyzed biochemical indicators, cell apoptosis, and metabolomic responses in cold-tolerant (Lv-T) and common (Lv-C) L. vannamei under low-temperature stress (18 °C and 10 °C). TUNEL analysis showed a significant increase in apoptosis of hepatopancreatic duct cells in L. vannamei under low-temperature stress. Biochemical analysis showed that Lv-T had significantly increased levels of superoxide dismutase (SOD) and triglycerides (TG), while alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH-L), and uric acid (UA) levels were significantly decreased compared to Lv-C (p < 0.05). Metabolomic analysis displayed significant increases in metabolites such as LysoPC (P-16:0), 11beta-Hydroxy-3,20-dioxopregn-4-en-21-oic acid, and Pirbuterol, while metabolites such as 4-Hydroxystachydrine, Oxolan-3-one, and 3-Methyldioxyindole were significantly decreased in Lv-T compared to Lv-C. The differentially regulated metabolites were mainly enriched in pathways such as Protein digestion and absorption, Central carbon metabolism in cancer and ABC transporters. Our study indicate that low temperature induces damage to the hepatopancreatic duct of shrimp, thereby affecting its metabolic function. The cold resistance mechanism of Lv-T L. vannamei may be due to the enhancement of antioxidant enzymes and lipid metabolism.

Effect of low-voltage electrostatic field-assisted partial freezing on large yellow croaker protein properties and metabolomic analysis during storage

BACKGROUND

Large yellow croaker is highly perishable during storage because of high protein and moisture content. The degradation of the fish is mainly attributed to microbial growth and enzyme activity, so it is important to find an efficient storage method to extend its shelf life.

METHODOLOGY

This study investigated the effect of a low-voltage electrostatic field combined with partial freezing treatment on the physicochemical properties of myofibrillar protein (MP) and metabolomic analysis of large yellow croaker during preservation. The samples in chilled storage (C), partial freezing storage (PF) and 6 kV/m low-voltage electrostatic field partial freezing storage (LVEF-PF) were analyzed during an 18 day storage period.

RESULTS

In comparison with the C and PF groups, LVEF-PF delayed the oxidation of MP by inhibiting the formation of carbonyl groups (2.25 nmol/mg pro), and maintaining higher sulfhydryl content (29.73 nmol/mg pro). Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy analysis also demonstrated that the LVEF-PF treatment maintained the stability of the protein structure by increasing the a-helix ratio (19.88%) and reducing the random coil ratio (17.83%). Scanning electron microscopy showed that, compared with the LVEF-PF group, there was more degeneration and aggregation of MP in the C and PF groups after 18 days' storage. The results of untargeted metabolomic analysis showed that 415 kinds of differential metabolites were identified after storage, and the difference levels of differential metabolites were least between the samples treated with LVEF-PF stored on the ninth day and the fresh samples. The main differential metabolic pathways during storage were amino acid metabolism and lipid metabolism.

CONCLUSION

The LVEF-PF treatment could maintain the stability of myofibrillar protein in large yellow croaker during storage. These results showed a potential application of the LVEF-PF method for aquatic product preservation. © 2023 Society of Chemical Industry.

Effect of oxygen supplement on post-mortem metabolic profile of shrimp during cold storage

Shrimp, renowned for its exceptional nutritional value, holds a pivotal position within the realm of aquatic products. The supplementation of extra oxygen to shrimp throughout the entire supply chain has found application within the commercial seafood market. In this study, a dual-platform metabolic analysis, coupled with multivariate data analysis, was employed to discern the impact of supplementary oxygen. Furthermore, this approach facilitated the construction of the post-mortem metabolic profile of shrimp during cold storage. A noticeable decrease of alcohols, ketones and carbohydrates which are related to the energy metabolism in shrimp has been found during cold storage, compared to the fresh shrimp. The degradation of nutritional amino acids was alleviated in shrimp after 4 h of extra oxygen supplement. Furthermore, a higher concentration of identified fatty acids, integral to lipid metabolism and functioning as flavor compounds was observed in shrimp subsequent to oxygen supplementation. Therefore, the additional oxygen supplementation exerted influence on multiple metabolic pathways, including nitrogen metabolism, amino acid and peptide metabolism, nucleotide metabolism, carbohydrate metabolism, and lipid metabolism. This study has constructed a comprehensive post-mortem metabolic profile of shrimp during cold storage, thereby establishing a theoretical foundation for the utilization of oxygen supplements in the preservation of seafood.

Effects of transportation on physiological indices and metabolomics of the large yellow croaker Larimichthys crocea

The aim of this study was to investigate the survival rate, biochemical indices, and metabolome changes of the large yellow croaker after 48 h of live transportation. Two hundred and forty large yellow croakers (body weight: 23.4 ± 5.3 g, total length: 12.2 ± 0.7 cm) were used in this experiment. The transport buckets were filled with fresh seawater and the parameters of the water were a temperature of 16 ± 0.5 °C and a dissolved oxygen content of 6.0-7.2 mg/L. Large yellow crokers were first divided to 0, 10, 20, and 30 mg/L MS-222 groups to observe the 12 h survival rate. The survival rate of 10 mg/L MS-222 group (T1) was the 95%, highest of all, and was further analyzed. The results of liver biochemical indices indicated inhibition of gluconeogenesis and pentose phosphate pathway metabolism. In addition, metabolomics analysis identified significantly differentially expressed metabolites between T1 group and 0 mg/L MS-222 control (C) groups. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) results revealed that the pathways of amino acid metabolism, especially the lysine, aspartate, and homoserine in the liver were significantly affected. In conclusion, the combination of metabolomics and liver biochemical assays provided a characterization of the response mechanism of L. crocea exposed to live transportation.

Waterless live transport degrades the flesh quality of Litopenaeus vannamei by disturbing neuroendocrine response: based on physiology and metabolomics

BACKGROUND

Shrimp is one of the most popular marine foods consumed throughout the world and its freshness is a crucial indicator for consumers. However, the flesh quality degradation of shrimp during waterless live transport has been observed and the underlying mechanism remains unknown.

RESULTS

The present study aimed to clarify the biochemistry mechanisms of flesh degradation with integration of quality evaluation, metabolic profiling and histopathological analysis. The flesh quality indicators such as water holding capacity, protein and lipid contents, amino acid composition and myofiber components degraded with the prolongation of combined stress. In addition, the metabolites including gamma-aminobutyric acid, Val-Ala, Trh and derivatives of carnitine, phosphocholine and prostaglandin all reduced significantly under combined stress (P < 0.05). Furthermore, Kyoto Encyclopedia of Genes and Genomes (https://www.genome.jp/kegg) analysis revealed the enrichment of neuroactive ligand-receptor interaction and estrogen signaling pathways, indicating the involvement of neuroendocrine in stress response. Moreover, architecture impairment in hepatopancreas tissue verified the accumulation of metabolic disturbance.

CONCLUSION

Taken together, the findings of the present study indicate that neuroendocrine system mediates the flesh degradation of L. vannamei during waterless transport by disturbing the biochemical metabolic pathways and inducing architecture impairment of myofibril components. © 2022 Society of Chemical Industry.

Integrated Transcriptomic and Metabolomic Analyses Reveal Low-Temperature Tolerance Mechanism in Giant Freshwater Prawn Macrobrachium rosenbergii

Water temperature, as an important environmental factor, affects the growth and metabolism of aquatic animals and even their survival. The giant freshwater prawn (GFP) Macrobrachium rosenbergii is a kind of warm-water species, and its survival temperature ranges from 18 °C to 34 °C. In this study, we performed transcriptomic and metabolomic analyses to clarify the potential molecular mechanism of responding to low-temperature stress in adult GFP. The treatments with low-temperature stress showed that the lowest lethal temperature of the GFP was 12.3 °C. KEGG enrichment analyses revealed that the differentially expressed genes and metabolites were both enriched in lipid and energy metabolism pathways. Some key genes, such as phosphoenolpyruvate carboxykinase and fatty acid synthase, as well as the content of the metabolites dodecanoic acid and alpha-linolenic acid, were altered under low-temperature stress. Importantly, the levels of unsaturated fatty acids were decreased in LS (low-temperature sensitive group) vs. Con (control group). In LT (low-temperature tolerant group) vs. Con, the genes related to fatty acid synthesis and degradation were upregulated to cope with low-temperature stress. It suggested that the genes and metabolites associated with lipid metabolism and energy metabolism play vital roles in responding to low-temperature stress. This study provided a molecular basis for the selection of a low-temperature tolerant strain.

Inflammation and apoptosis pathways mediated the stress response of Litopenaeus vannamei to acute cold and air exposure during waterless live transportation: Based on ultrastructure and transcriptome

the combination of acute cold (AC) and waterless duration (WD) constitutes the major environmental stress and induces the damage or even mortality to shrimp L. vannamei during live transport, whereas the responding mechanism to AC + WD at molecular level remains unknown. The present study aims to clarify the responding mechanism of L. vannamei to AC + WD stress by ultrastructural observation and transcriptomic analysis on hepatopancreas tissue. The results showed that the dramatical oxidative stress induced by AC + WD significantly mediated the alteration of amino acids and energy metabolism. Furthermore, KEGG pathway enrichment analysis revealed that the genes including DDO, GOT1, IDH1 and BBOX1 involved in energy metabolism and were significantly down-regulated, while some apoptosis- and inflammation-related genes such as DRONC, AP-1, and COX-2 were significantly up-regulated under AC + WD stress in comparison with those at normal control (all p < 0.05 or 0.01). These findings suggested that metabolic processes mediate the stress-induced damages of L. vannamei during waterless transport. Moreover, the significant overexpression of apoptosis-and inflammation-related proteins, and levels of inflammation cytokines in serum of shrimps strongly demonstrated the implication of inflammation and apoptosis pathways in stress-induced ultrastructural damage. These findings deepen our understanding into the response mechanisms of L. vannamei to AC + WD stress and provide the potential controlling biomarkers for transportation management.