Enhancement of Nutrient Composition and Non-Volatile Flavor Substances in Muscle Tissue of Red Drum (Sciaenops ocellatus) Through Inland Low Salinity Saline-Alkaline Water Culture.

The red drum (Sciaenops ocellatus), a globally significant marine aquaculture species, boasts formidable osmoregulatory capabilities and remarkable adaptability to low salinity, making it an ideal candidate for commercial cultivation in inland low salinity saline-alkaline waters. However, studies on the fundamental nutritional composition and flavor quality of S. ocellatus in these inland low salinity saline-alkaline waters remain unreported. This study delves into the impact of inland low salinity saline-alkaline environments on the basic nutritional components and nonvolatile flavor substances (including free amino acids and free nucleotides) in the muscle tissue of S. ocellatus. The findings reveal that redfish cultivated in these conditions exhibit a significant increase in the crude fat, ash, and protein content in their dorsal muscle tissue, coupled with a decrease in moisture content (p < 0.05), indicating an enhancement in the nutritional value of the dorsal muscle tissue. Furthermore, this cultivation environment significantly elevates the content of free amino acids in the muscle tissue (p < 0.05), particularly those contributing to umami and sweet tastes, while reducing the relative content of bitter amino acids. Although the total content of free nucleotides decreased, the equivalent umami concentration (EUC) in the muscle tissue markedly increased (p < 0.05) due to the synergistic effect of umami amino acids and flavor nucleotides, enhancing the umami taste characteristics. Therefore, inland low salinity saline-alkaline aquaculture not only elevates the nutritional value of S. ocellatus muscle tissue but also improves its umami flavor characteristics. This discovery opens new perspectives for further research into the impact of inland low salinity saline-alkaline environments on the flavor properties of marine animals.

Shrimp Cultured in Low-Salt Saline-Alkali Water has a Better Amino Acid Nutrition and Umami─Comparison of Flavors between Saline-Alkali Water- and Seawater-Cultured Litopenaeus vannamei.

The advantages of Litopenaeus vannamei farming in saline-alkali water have gradually attracted attention, but few studies have focused on its flavor. In this study, L. vannamei cultured in saline-alkali water (SS) and ordinary seawater (CS) (both have a breeding time of 120 days) were selected for analysis (n = 5). High-performance liquid chromatography (HPLC) was used to measure free amino acids and flavoring nucleotides in the muscles of L. vannamei, while the taste activity value (TAV) and equivalent umami concentration (EUC) were used to analyze the degree of umami. The total essential amino acids (TEAA) in the SS group were 238.41 ± 46.24 mg/mL, significantly higher than that in the CS group (107.06 ± 15.65 mg/mL). The total amount of flavor nucleotides in the SS group was 2948.51 ± 233.66 µg/mL, significantly higher than those in the CS group (2530.37 ± 114.67 µg/mL). The content and TAV of some free amino acids (Glu, Cys-s) in the SS group were significantly higher. Meanwhile, due to the significant increase in IMP, the synergistic effect of free amino acids and flavored nucleotides leads to higher EUC. The significant separation of SS and CS samples in principal component analysis (PCA) indicates a significant difference between the two groups. Our results indicate that shrimp cultured in saline-alkali water has a stronger umami. This study enriches the basic theories related to the flavor of salt-alkali water crustaceans.

Comparative Transcriptome Analysis Reveals the Light Spectra Affect the Growth and Molting of Scylla paramamosain by Changing the Chitin Metabolism.

Light is an essential ecological factor that has been demonstrated to affect aquatic animals' behavior, growth performance, and energy metabolism. Our previous study found that the full-spectrum light and cyan light could promote growth performance and molting frequency of Scylla paramamosain while it was suppressed by violet light. Hence, the purpose of this study is to investigate the underlying molecular mechanism that influences light spectral composition on the growth performance and molting of S. paramamosain. RNA-seq analysis and qPCR were employed to assess the differentially expressed genes (DEGs) of eyestalks from S. paramamosain reared under full-spectrum light (FL), violet light (VL), and cyan light (CL) conditions after 8 weeks trial. The results showed that there are 5024 DEGs in FL vs. VL, 3398 DEGs in FL vs. CL, and 3559 DEGs in VL vs. CL observed. GO analysis showed that the DEGs enriched in the molecular function category involved in chitin binding, structural molecular activity, and structural constituent of cuticle. In addition, the DEGs in FL vs. VL were mainly enriched in the ribosome, amino sugar and nucleotide sugar metabolism, lysosome, apoptosis, and antigen processing and presentation pathways by KEGG pathway analysis. Similarly, ribosome, lysosome, and antigen processing and presentation pathways were major terms that enriched in FL vs. CL group. However, only the ribosome pathway was significantly enriched in up-regulated DEGs in VL vs. CL group. Furthermore, five genes were randomly selected from DEGs for qPCR analysis to validate the RNA-seq data, and the result showed that there was high consistency between the RNA-seq and qPCR. Taken together, violet light exposure may affect the growth performance of S. paramamosain by reducing the ability of immunity and protein biosynthesis, and chitin metabolism.

Recirculating aquaculture system as microbial community and water quality management strategy in the larviculture of Scylla paramamosain.

The structure and function of the water microbial community can change dramatically between different rearing modes. Yet investigations into the relationships between microbial community and water quality remain obscure. We provide the first evidence that rearing modes alter bacterial community and water quality in the rearing water of the mud crab (Scylla paramamosain) larvae. The juveniles in the recirculating aquaculture system (RAS) had a higher viability than those in the water exchange system (WES). RAS had the significantly lower levels of total ammonia nitrogen (TAN), NH3, NO2--N, total nitrogen (TN), total dissolved solids (TDS), and chemical oxygen demand than those of WES. The number of significantly different amplicon sequence variants between rearing modes increased as the larvae developed. NH3, TAN, TDS, NO2--N, and TN were closely related to the late alterations in water bacterial community. Both the FAPROTAX tool and quantitative PCR analysis showed enhanced nitrogen cycling functional potential of water bacterial community of RAS. Random forest analysis identified the enriched water bacteria especially heterotrophic bacteria such as Phaeodactylibacter, Tenacibaculum, and Hydrogenophaga, which were vital in removing nitrogenous compounds via simultaneous nitrification and denitrification. Notably, RAS could save 18.5 m3 of seawater relative to WES in larviculture on the scale of 2.5 m3. Together, these data indicate that RAS could function as microbial community and water quality management strategy in the larviculture of crab.

The combined effects of microplastics and bisphenol-A on the innate immune system response and intestinal microflora of the swimming crab Portunus trituberculatus.

Microplastics (MPs) and bisphenol-A (BPA) have been shown to have toxic effects on aquatic organisms. However, data on the combined effects of MPs and BPA on the innate immune system response and intestinal microorganisms of crabs are limited. Here, Portunus trituberculatus were exposed to BPA (at a concentration of 100 µg/L), MPs (microbeads of polystyrene with a particle size of 1 µm and at a concentration of 1 × 106 particles/L) or BPA+MPs for 21 days were tested at the tissue, cellular, and molecular levels. The results showed that neither the single nor combined exposure of MPs and BPA had a significant impact on the growth of crabs. However, intestinal histology study found that the intestinal villi of crabs in the BPA treated group, MP treated group and MP+BPA treated group appeared abnormal. Overall, compared with the control group and the single pollutant exposure group, co-exposure to the MP and BPA generally led to a significant increase in MDA and SOD activity and a significant decrease in CAT activity, and the activation of MyD88, Crustin-1, TARF6, Cu/Zn-SOD, Lyz, Toll-2 and NOX gene expression levels were significantly up-regulated. Co-exposure induced disorders of the intestinal microbial community of crabs, resulting in an increase in the abundance of harmful bacteria and a decrease in the abundance of beneficial bacteria. This study shows that the combined exposure of MPs and BPA can exacerbate the intestinal toxicity of a single pollutant to P. trituberculatus.

Cellular localization and potential ligands of a novel scavenger receptor class B/CD36 protein homolog (Pt-SRB2) identified in the marine crab, Portunustrituberculatus.

The scavenger receptor class B family proteins (SRB) are multiligand membrane receptor proteins. Herein, a novel SRB homolog (Pt-SRB2) was identified in Portunus trituberculatus. The open reading frame of Pt-SRB2 was predicted to encode 520 amino acid residues comprising a typical CD36 domain. Phylogenetic analysis showed that Pt-SRB2 distinctly clustered with the SRB homologs of most crustaceans and Drosophila but was separate from all vertebrate CD36/SRB. Semi-quantitative and Real-time quantitative PCR revealed that the abundance of Pt-SRB2 transcripts was the highest in hepatopancreas than in other tested tissues. Overexpressed Pt-SRB2 was distributed primarily in the cell membrane and cytoplasm of HEK293T or Drosophila Schneider 2 cells. In crab hemocytes, Pt-SRB2 was distributed primarily in the cell membrane by immunofluorescence staining. In addition, the immunofluorescence staining showed that green fluorescence signals were mainly located in the inner lumen membrane of the hepatopancreatic tubules. Moreover, solid-phase enzyme-linked immunosorbent assay revealed that rPt-SRB2-L exhibited relative high affinity with lipopolysaccharides, and relative moderate binding affinity with lipoteichoic acid or peptidoglycan. Of note, rPt-SRB2-L showed high binding affinity with eicosapentaenoic acid among a series of long-chain polyunsaturated fatty acids. Taken together, this study provided valuable data for understanding the functions of the crab CD36/SRB.

Optimizing Anesthetic Practices for Mud Crab: A Comparative Study of Clove Oil, MS-222, Ethanol, and Magnesium Chloride.

Anesthesia serves as an effective method to mitigate the stress response in aquatic animals during aquaculture and product transportation. In this study, we assessed the anesthetic efficacy of clove oil, tricaine methane-sulfonate (MS-222), ethanol, and magnesium chloride by anesthesia duration, recovery time, 24-hour survival rate, and the behavior of mud crabs (Scylla paramamosain). Additionally, the optimal anesthetic concentration for varying body weights of mud crabs was also investigated. The results revealed that clove oil emerged as the optimal anesthetic for mud crabs, with a 24-hour survival rate surpassing those observed in MS-222 and magnesium chloride treatments. Ethanol caused amputation and hyperactivity in mud crabs. Regression analyses between the optimal anesthetic concentration of clove oil and the weight categories of 0.03-27.50 g and 27.50-399.73 g for mud crabs yielded the following equations: y = 0.0036 x3 - 0.1629 x2 + 1.7314 x + 4.085 (R2 = 0.7115) and y = 0.0437 x + 2.9461 (R2 = 0.9549). Clove oil exhibited no significant impact on serum cortisol, glucose, lactate content, aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, or superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels in mud crabs across different treatment groups. Anesthesia induced by clove oil in mud crabs resulted in an increase in inhibitory neurotransmitters such as glycine. However, the recovery from anesthesia was associated with elevated levels of the excitatory neurotransmitters L-aspartic acid and glutamate. In conclusion, clove oil proves to be a safe and optimal anesthetic agent for mud crabs, exerting no physiological stress on the species.

Effect of Domestication on Nonvolatile Flavor Substances in Mud Crabs (Scylla paramamosain): A Way to Improve the Quality of Commercial Crabs.

In this study, the best domestication time for mud crabs (Scylla paramamosain) that were domesticated in the same region was explored. MC crabs (Mang Cai City, Vietnam), TS crabs (Taishan City, Guangdong Province, China), and NB crabs (Ningbo City, Zhejiang Province, China) were used as experiment groups, which were all domesticated in the Sanmen area for 28 days. Then, free amino acids and flavor nucleotides in muscles and hepatopancreas were determined. In MC and NB crabs, flavor amino acids in hepatopancreas and equivalent umami concentration (EUC) of flavor nucleotides in the hepatopancreas and muscles were lower than those of CK1 and CK3 crabs before domestication (0 day). There was no significant difference between MC and CK1 and between NB and CK3 crabs after 28 days of domestication. The content of umami amino acids, the total content of flavor nucleotides, and EUC in the hepatopancreas in TS crabs were lower than those in CK2 crabs and were still lower than those in CK2 crabs after 28 days of domestication. Therefore, it takes at least a month to domesticate mud crabs. The theoretical basis and technical reference for the directional cultivation of the flavor quality of mud crabs were provided in this study..

The shared microbiome in mud crab (Scylla paramamosain) of Sanmen Bay, China: core gut microbiome.

Introduction: The mud crab, Scylla paramamosain, holds great commercial significance as a marine crustacean widely cultivated in the Indo-Pacific region. Understanding the core gut microbiota of aquatic animals is crucial for their overall health and growth, yet the core gut microbiota of mud crab remains poorly characterized. Methods: In this study, we gathered gut samples from mud crabs across five locations within Sanmen Bay, China. Through the utilization of high-throughput sequencing, we delved into the composition of the gut microbial community and identified the core gut microbiome of mud crab. Results: Our results demonstrate that the gut microbial diversity of mud crab did not exhibit significant variation among the five sampling sites, although there were some differences in community richness. At the phylum level, we identified 35 representative phyla, with Firmicutes, Proteobacteria, Bacteroidota, and Campilobacterota as the dominant phyla. Among the 815 representative genera, we discovered 19 core genera, which accounted for 65.45% of the total sequences. These core genera were distributed across 6 phyla, and among them, Photobacterium exhibited the highest average relative abundance. Discussion: Photobacterium has probiotic activity and may play a crucial role in enhancing the immune response of the host and maintaining the diversity of the gut microbiota. Moreover, we observed a positive correlation between the relative abundance of core genera and the stability of the gut microbial community. Furthermore, our findings revealed distinct differences in gut microbial composition and specific taxa between the sexes of mud crab. These differences subsequently influenced the functionality of the gut microbial community. Overall, our investigation sheds light on the core gut microbiota of mud crab, emphasizing the importance of core gut microbial communities in maintaining the health and growth of these commercially significant marine crustaceans.

Rise and metabolic roles of Vibrio during the fermentation of crab paste.

Microbial community may systematically promote the development of fermentation process of foods. Traditional fermentation is a spontaneous natural process that determines a unique nutritional characteristic of crab paste of Portunus trituberculatus, However, rare information is available regarding the development pattern and metabolic role of bacterial community during the fermentation of crab paste. Here, using a 16S rRNA gene amplicon sequencing technology, we investigated dynamics of bacterial community and its relationship with metabolites during the fermentation of crab paste. The results showed that bacterial community changed dynamically with the fermentation of crab paste which highlighted by consistently decreased α-diversity and overwhelming dominance of Vibrio at the later days of fermentation. Vibrio had a positive correlation with trimethylamine, hypoxanthine, formate, and alanine while a negative correlation with inosine and adenosine diphosphate. In contrast, most of other bacterial indicators had a reverse correlation with these metabolites. Moreover, Vibrio presented an improved function potential in the formation of the significantly increased metabolites. These findings demonstrate that the inexorable rise of Vibrio not only drives the indicator OTUs turnover in the bacterial community but also has incriminated the quality of crab paste from fresh to perished.

Optimization of Sperm Cryopreservation Formulation in Portunus trituberculatus.

Portunus trituberculatus is a very important marine economic species, and its aquaculture industry has been developing rapidly. However, the phenomenon of marine wild capture of P. trituberculatus and germplasm degradation has become increasingly serious. It is necessary to develop the artificial farming industry and carry out germplasm resource protection, for which sperm cryopreservation technology is an effective method. This research compared three methods (mesh-rubbing, trypsin digestion, and mechanical grinding) for acquiring free sperm, and the best method was mesh-rubbing. Then, the optimal cryopreservation conditions were selected, and the optimal formulation was sterile calcium-free artificial seawater, the optimal cryoprotectant was 20% glycerol, and the best equilibrium time was 15 min at 4 °C. The optimal cooling program was suspending the straws at 3.5 cm on the liquid nitrogen surface for 5 min and then storing them in liquid nitrogen. Finally, the sperm were thawed at 42 °C. However, the expression of sperm-related genes and the total enzymatic activities of frozen sperm were significantly decreased (p < 0.05), which showed that sperm cryopreservation damaged the sperm. Our study improves the sperm cryopreservation technology and the yield of aquaculture in P. trituberculatus. Additionally, the study provides a certain technical basis for the establishment of a sperm cryopreservation library of crustaceans.

Adaptive changes of swimming crab (Portunus trituberculatus) associated bacteria helping host against dibutyl phthalate toxification.

The pollution of dibutyl phthalate (DBP) in aquatic environments is becoming an extensive environmental problem and detrimental to aquatic animals. Here, we quantified the response pattern of the bacterial community and metabolites of swimming crab (Portunus trituberculatus) juveniles exposed to 0.2, 2, and 10 mg/L DBP using 16 S rRNA gene amplicon sequencing coupled with metabolomic technique. The results showed that DBP changed the bacterial community compositions in a concentration-dependent pattern and decreased the Shannon index at the second developmental stage of the swimming crabs. The Rhodobacteraceae taxa were specifically enriched by crabs when challenged by 2 and 10 mg/L DBP, with an increased in Shannon index and enhanced drift in its assembly. Moreover, DBP changed the metabolic profiling of the swimming crab, highlighted by increased levels of lactate, valine, methionine, lysine, and phenylalanine in the 10 mg/L DBP-exposed crabs. Rhodobacteraceae presented the most considerable contribution to the metabolic potentials in phthalate and benzoate degradation, lactate production, and amino acid biosynthesis. Overall, our results indicated an adaptive change of crab-associated bacteria helped the host resist DBP stress. The findings extend our insights into the relationship between the microbiota and its host metabolism under DBP stress and reveal the potential microbiota modalities for DBP detoxification.

The Functions of Pt-DIC and Pt-Lamin B in Spermatogenesis of Portunus trituberculatus.

Cytoplasmic Dynein is a multiple-subunit macromolecular motor protein involved in the transport process of cells. The Dynein intermediate chain (DIC) is one of the subunits of Dynein-1. In our previous studies, we showed that Pt-DIC may play an important role in the nuclear deformation of spermiogenesis in Portunus trituberculatus. Lamin B is essential for maintaining nuclear structure and functions. Surprisingly, Pt-Lamin B was expressed not only in the perinucleus but also in the pro-acrosome during spermiogenesis in P. trituberculatus. Studies have also shown that Dynein-1 can mediate the transport of Lamin B in mammals. Thus, to study the relationship of Pt-DIC and Pt-Lamin B in the spermatogenesis of P. trituberculatus, we knocked down the Pt-DIC gene in P. trituberculatus by RNAi. The results showed that the distribution of Pt-DIC and Pt-Lamin B in spermiogenesis was abnormal, and the colocalization was weakened. Moreover, we verified the interaction of Pt-DIC and Pt-Lamin B via coimmunoprecipitation. Therefore, our results suggested that both Pt-DIC and Pt-Lamin B were involved in the spermatogenesis of P. trituberculatus, and one of the functions of Dynein-1 is to mediate the transport of Lamin B in the spermiogenesis of P. trituberculatus.

Time-Restricted Feeding Could Not Reduce Rainbow Trout Lipid Deposition Induced by Artificial Night Light.

Artificial night light (ALAN) could lead to circadian rhythm disorders and disrupt normal lipid metabolism, while time-restricted feeding (TRF) could maintain metabolic homeostasis. In mammals, TRF has been demonstrated to have extraordinary effects on the metabolic regulation caused by circadian rhythm disorders, but studies in lower vertebrates such as fish are still scarce. In this study, the impacts of ALAN on the body composition and lipid metabolism of juvenile rainbow trout were investigated by continuous light (LL) exposure as well as whether TRF could alleviate the negative effects of LL. The results showed that LL upregulated the expression of lipid synthesis (fas and srebp-1c) genes and suppressed the expression of lipid lipolysis (pparß, cpt-1a, and lpl) genes in the liver, finally promoting lipid accumulation in juvenile rainbow trout. However, LL downregulated the expression of genes (Δ6-fad, Δ9-fad, elovl2, and elovl5) related to long-chain polyunsaturated fatty acid (LC-PUFA) synthesis, resulting in a significant decrease in the proportion of LC-PUFA in the dorsal muscle. In serum, LL led to a decrease in glucose (Glu) levels and an increase in triglyceride (TG) and high-density lipoprotein cholesterol (H-DLC) levels. On the other hand, TRF (mid-dark stage feeding (D)) and mid-light stage feeding (L)) upregulated the expression of both the lipid synthesis (srebp-1c and pparγ), lipolysis (pparα, pparß, and cpt-1a), and lipid transport (cd36/fat and fatp-1) genes, finally increasing the whole-body lipid, liver protein, and lipid content. Meanwhile, TRF (D and L groups) increased the proportion of polyunsaturated fatty acid (PUFA) and LC-PUFA in serum. In contrast, random feeding (R group) increased the serum Glu levels and decreased TG, total cholesterol (T-CHO), and H-DLC levels, suggesting stress and poor nutritional status. In conclusion, ALAN led to lipid accumulation and a significant decrease in muscle LC-PUFA proportion, and TRF failed to rescue these negative effects.

ATP catabolism and bacterial succession in postmortem tissues of mud crab (Scylla paramamosain) and their roles in freshness.

The seafood microbiome is highly diverse and plays an essential role in the spoilage of seafood. Nevertheless, how such a diverse microbiome influences freshness of mud crab (Scylla paramamosain) remains unclear. Here we investigated the postmortem ATP catabolism and succession of the bacterial community in the hepatopancreas and muscle of S. paramamosain using a high-performance liquid chromatography method and 16S rRNA gene amplicon sequencing. Our results showed a tissue-dependent change in ATP catabolism determinized the differences in the changes of nucleotide freshness indices of hepatopancreas and muscle over postmortem time of mud crab. The muscle K value could be used as an optimal nucleotide freshness indicator for the freshness of mud crab, with a proposed threshold of 20%. From a microbiota perspective, a more significant bacterial community change was observed in the muscle than in the hepatopancreas. These changes could result in a close relationship between ATP and its catabolites and microbial taxa in the muscle. Moreover, Photobacterium, Peptostreptococcaceae, average path distance, OTU richness, and Shannon index of muscle bacterial community markedly contributed to K value. These findings suggest that the mud crab of 4 h postmortem at room temperature is still edible. Notably, the importance of microbial community composition and interaction for the spoilage of mud crab should be carefully considered.

Accumulation, detoxification, and toxicity of dibutyl phthalate in the swimming crab.

Dibutyl phthalate (DBP) is one of the most commonly used and toxic phthalate esters and has a variety of harmful effects on aquatic animals. However, there is still a lack of knowledge on the accumulation, detoxification, and toxicity of DBP in aquatic animals. In this study, we chose the swimming crab Portunus trituberculatus, an ecologically and economically important species, as the model and investigated the metabolism of DBP and its effects on the detoxification, antioxidation, survival and growth of the crab juveniles to better understand DBP-triggered molecular response over different time courses. As a result, DBP could be accumulated in the swimming crab in a concentration-dependent manner and metabolized to monobutyl phthalate (MBP) and phthalic acid (PA) through de-esterification. DBP exposure induced the different responses of three cytochrome P450 members and antioxidant enzyme genes, enhanced gene transcript and protein levels of glutathione-S-transferase and two heat stress proteins and malondialdehyde accumulation, decreased glutathione level, and inhibited antioxidant enzyme activities. Further, no significant effect of DBP was observed in crab survival, size, and weight but there was molting retardation. Therefore, DBP induced strong detoxification and antioxidative defense mechanisms to overcome detrimental effects of DBP on the swimming crab juveniles despite a molting retardation as a trade-off in fitness costs. The prevalent coexistence of DBP with MBP and PA during the whole exposure period is raising concerns on the combined action and ecological risk to aquatic animals.

Elevated pCO2 alters the interaction patterns and functional potentials of rearing seawater microbiota.

Mean oceanic CO2 values have already risen and are expected to rise further on a global scale. Elevated pCO2 (eCO2) changes the bacterial community in seawater. However, the ecological association of seawater microbiota and related geochemical functions are largely unknown. We provide the first evidence that eCO2 alters the interaction patterns and functional potentials of microbiota in rearing seawater of the swimming crab, Portunus trituberculatus. Network analysis showed that eCO2 induced a simpler and more modular bacterial network in rearing seawater, with increased negative associations and distinct keystone taxa. Using the quantitative microbial element cycling method, nitrogen (N) and phosphorus (P) cycling genes exhibited the highest increase after one week of eCO2 stress and were significantly associated with keystone taxa. However, the functional potential of seawater bacteria was decoupled from their taxonomic composition and strongly coupled with eCO2 levels. The changed functional potential of seawater bacteria contributed to seawater N and P chemistry, which was highlighted by markedly decreased NH3, NH4+-N, and PO43--P levels and increased NO2--N and NO3--N levels. This study suggests that eCO2 alters the interaction patterns and functional potentials of seawater microbiota, which lead to the changes of seawater chemical parameters. Our findings provide new insights into the mechanisms underlying the effects of eCO2 on marine animals from the microbial ecological perspective.

Integrated metabolomics and transcriptomics reveal the anti-aging effect of melanin from Sepiella maindroni ink (MSMI) on D-galactose-induced aging mice.

Sepiella maindroni ink, a flavoring and coloring agent in food, has attracted considerable attention due to its various pharmacological activities. Our previous study showed that the melanin of Sepiella maindroni ink (MSMI) can alleviate oxidative damage and delay aging in D-galactose(D-gal)-induced aging mice. This study aimed to reveal the possible mechanisms of the anti-aging effect of MSMI. In this article, a comprehensive analysis of gas chromatography-mass spectrometry (GC-MS)-based metabolomics and microarray-based transcriptomics revealed that 221 mRNAs were differentially expressed and 46 metabolites were significantly changed in the anti-aging progress of MSMI. Integrated analysis of transcript and metabolic profiles indicated that MSMI mainly altered carbohydrate metabolism, lipid metabolism, and insulin signaling pathway. MSMI achieved anti-aging effects not only by reducing oxidative damage and sorbitol toxicity but also by regulating lipid metabolism, improving insulin sensitivity, and reducing the formation of advanced glycation end products (AGEs). Moreover, our findings firstly demonstrated that MSMI could increase the expression of interferon-induced proteins and might be a potential antiviral compound.

The iTRAQ-based quantitative proteomics reveals metabolic changes in Scylla paramamosain under different light intensities during indoor overwintering.

Light intensity is one of the ecological factors that appreciably affects the metabolism of Scylla paramamosain during overwintering. This study adopted the isobaric tag for relative and absolute quantitation (iTRAQ) method to investigate metabolic changes of S. paramamosain under three illumination levels (0, 1.43 and 40.31 µmol m-2·s-1) for four months during indoor overwintering. The iTRAQ identified 3282 proteins, among which 267 exhibited significant differential expression (122 upregulated and 145 downregulated) in the low light group, and 299 with significant differential expression (252 upregulated and 47 downregulated) in the high light group. Analysis of these results showed that there were different metabolic regulatory patterns under different light intensities. Low light is more conducive to the survival of S. paramamosain, which needs to produce and consume relatively less energy to sustain physiological activities. Thus, the essential proteins associated with physiological activities were significantly upregulated, while those related to energy production were significantly downregulated. In contrast, high light exerts a certain stress on the survival of S. paramamosain and required more energy to cope with this stress, which forced a significant upregulation of proteins related to stress response and energy production. The findings of this study highlighted the metabolic regulatory mechanisms of S. paramamosain under different light intensities.

Transcriptome analysis of genes and pathways associated with metabolism in Scylla paramamosain under different light intensities during indoor overwintering.

BACKGROUND: Scylla paramamosain is one of the commercially crucial marine crustaceans belonging to the genus Scylla, which is commonly distributed along the coasts of China, Vietnam, and Japan. Genomic and transcriptomic data are scarce for the mud crab. Light intensity is one of the ecological factors that affect S. paramamosain during indoor overwintering. To understand the energy metabolism mechanism adapted to light intensity, we analyzed the transcriptome of S. paramamosain hepatopancreas in response to different light intensities (0, 1.43, 40.31 µmol·m- 2·s- 1). RESULTS: A total of 5052 differentially expressed genes were identified in low light group (LL group, 3104 genes were up-regulated and 1948 genes were down-regulated). A total of 7403 differentially expressed genes were identified in high light group (HL group, 5262 genes were up-regulated and 2141 genes were down-regulated). S. paramamosain adapts to different light intensity environments through the regulation of amino acids, fatty acids, carbon and energy metabolism. Different light intensities had a strong impact on the energy generation of S. paramamosain by influencing oxygen consumption rate, aerobic respiration, glycolysis/gluconeogenesis pathway, the citrate cycle (TCA cycle) and fatty acid degradation. CONCLUSION: Low light is more conducive to the survival of S. paramamosain, which needs to produce and consume relatively less energy to sustain physiological activities. In contrast, S. paramamosain produced more energy to adapt to the pressure of high light intensities. The findings of the study add to the knowledge of regulatory mechanisms related to S. paramamosain metabolism under different light intensities.