Marine Biotechnology最新文献

As an abiotic stress factor, salinity significantly affects the physiological activities of crustaceans. In this study, transcriptome sequencing was used to evaluate the mechanism of ion transport and the physiological response of black tiger shrimp (Penaeus monodon) under low salt stress. Four hundred post larval (PL) stage P. monodon were distributed in eight experimental tanks and exposed to 3 or 5 ppt salt concentrations for 96 h. Low salinity significantly reduced the survival rate of shrimp but simultaneously activated the activity of ion transporter enzymes Na⁺/K⁺-ATPase (NKA) and Ca²⁺/Mg²⁺-ATPase), the expression of NKA, galectin 10, and cytochrompe c peroxidase genes, and the activity and expression of antioxidant-related genes (superoxide dismutase, catalase, heat shock protein 60). Low salt stress activated the urea cycle but significantly inhibited glutathione metabolization-related indicators (glutamate dehydrogenase, glutaminase, glutamic acid). RNA-seq analysis identified 221 differentially expressed genes (78 up-regulated and 143 down-regulated). Quantitative real-time PCR and RNA-seq results of 11 of them were consistent, illustrating the validity of the transcriptomic predictions. Gene set enrichment analysis results showed that calcium ion transmembrane transport, calmodulin binding, the stress-activated protein kinase signaling cascade, and regulation of the cytosolic calcium ion concentration process were significantly enriched. These results showed that low salt stress activated the calcium-dominated ion transport pathway and promoted molting growth of P. monodon. They also indicate that there is potential for larval rearing shrimp under low salt conditions.

Large yellow croaker (Larimichthys crocea) is facing various threats from bacterial, viral, and parasitic diseases, especially scuticociliate. Scuticociliate is a facultative parasite causing high mortality in various marine fishes. In this study, an artificial scuticociliate infection model was successfully established for large yellow croaker. Comparative transcriptome analysis was performed on gill tissues collected from control fish and fish at the peak of mortality following exposure to the parasite to investigate the underlying molecular mechanisms of host-parasite interactions. A total of 400, 427, and 311 differential alternative splicing (DAS) events were identified at 7 d/0 h, 8 d/0 h, and 9 d/0 h, respectively. Meanwhile, 761 differentially expressed genes (DEGs) were found, with 154 simultaneously at three time points. GO and KEGG enrichment analysis showed that DAS genes and DEGs were mainly focused on self-respire, immune, and metabolic-related pathways. The DEGs related to blood coagulation included fga, fgb, fgg, and lectin domain genes. Lectin domain genes were also involved in reducing parasite burden. Cytokines, Caspase-1, trim13, trim16, and trim39 co-participated in immune response. Notably, the complement component gene c3 was both a DEG and underwent DAS. Using STRING software, interaction regulatory networks were constructed to visualize potential hub genes, revealing 22 DEGs shared across at least two time points. These findings provide valuable insights into the immune and metabolic responses of large yellow croaker to scuticociliate infection, offering a foundational reference for identifying resistant genes and understanding fish-parasite interactions.

Fucoidan from Apostichopus japonicus (Aj-FUC) has shown anti-inflammatory activity, whereas its mechanism was not explicated. This study investigated the anti-inflammatory potential and mechanism of the fucoidan from green and purple A. japonicus (G-FUC and P-FUC) in lipopolysaccharide (LPS)-treated RAW264.7 cells. Results showed that Aj-FUCs at 25–400 µg/mL had no toxicity to cells after 24 h stimulation and promoted cell phagocytic activity. ELISA results indicated that Aj-FUC reduced the nitric oxide (NO), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6 levels and increased IL-10 level. The Aj-FUC suppressed transcription of inflammatory-related genes (tnf-α, il-1β, il-6, nlrp3, inos, cox-2, tlr4, trif, and nf-κb) in LPS-treated RAW264.7 cells, among which G-FUC had stronger anti-inflammatory effects. Moreover, Aj-FUC upregulated the mRNA expression of autophagic genes (beclin1, lc3II, and lamp2). The immunoblotting and immunofluorescence analyses of Beclin-1 and LC3II supported that Aj-FUC enhanced autophagy activity. After autophagy inhibited by 3-methyladenine, the mRNA expressions of tnf-α, il-6, il-1β, and nlrp3 were significantly upregulated in LPS-induced cells treated with Aj-FUC, suggesting the suppressed inflammation by Aj-FUC mediated via autophagy. Summarily, the present study demonstrated that Aj-FUC showed anti-inflammatory effects by elevating autophagy activity in LPS-induced macrophages.

Graphical Abstract

Application of algicides produced by naturally occurring bacteria is considered an environmentally friendly approach to control harmful algal blooms. However, few studies assess the effects of bacterial algicides on non-target species, either independently or with other stressors. Here, we measured sub-lethal effects of dinoflagellate-specific algicide IRI-160AA on the estuarine fish Fundulus heteroclitus and Menidia menidia in laboratory experiments. Plasma cortisol levels were measured to test whether a neuroendocrine stress response was induced in these fish following exposure to the algicide alone, and in combination with diel-cycling hypoxia and/or pH, at 25 and 30 °C. Results show that exposure to IRI-160AA does not significantly affect cortisol levels in either species, at either temperature tested, whether exposure occurs independently or with co-occurring hypoxia and/or pH cycles as potential multiple stressors. These results support the application of IRI-160AA as an environmentally friendly approach to control harmful algal blooms in estuarine environments.

The influence of sex and heredity on DNA methylation in the somatic tissues of mice has been well-documented, with similar hereditary effects reported in honeybees. However, the extent to which these factors affect DNA methylation in molluscan somatic tissues remains poorly understood. In this study, we investigated genomic DNA methylation patterns in the adductor muscle of two genetically distinct oyster strains using whole-genome bisulfite sequencing (WGBS). Our analysis identified significant differences in DNA methylation between sexes, with females exhibiting a global reduction compared to males. Furthermore, approximately half of the differentially methylated sites between the two parental strains were conserved in their offspring. Regions with differential methylation in parents typically exhibited intermediate methylation levels in the F1 progeny, whereas consistently methylated regions in parents maintained similar methylation levels in their progeny. These findings suggest that offspring DNA methylation is strongly influenced by parental methylation profiles, highlighting its potential role in sexual determination in oysters.

In China, the red swamp crayfish (Procambarus clarkii), a notorious invasive species, has become an important economic freshwater species. In order to compare the genetic diversity and population structure of crayfish from northern and southern China, we collected 60 crayfish individuals from 4 crayfish populations in northern China and 2 populations in southern China for sequencing using the 2b-RAD technique. Additionally, the whole genome sequence information obtained by 2b-RAD of 90 individuals from 2 populations in northern China and 7 populations in southern China were downloaded from NCBI. After quality control, a total of 25,371 SNPs were detected from approximately 54.22 billion raw reads. Based on these SNPs, high genetic diversity was observed in the 15 crayfish populations in China. The pairwise F_ST values indicated that there was a large genetic differentiation of crayfish populations in northern and southern China. Despite common genetic backgrounds, due to geographical barriers, genetic divergence has been observed in northern and southern China crayfishes. The principal component analysis in combination with Admixture and Neighbor-Joining tree analysis showed that the crayfish fell into two clusters corresponding to geographical regions. The integrated analysis of whole genome and transcriptome data showed that two genes (CETN4 and CPEB2) might play important roles during crayfish resistance to a cold environment. This study reveals the genetic differentiation of crayfish populations in northern and southern China and provides clues to the genetic mechanism related to cold adaptation.

Recently, the scale and frequency of harmful algae blooms (HABs) have gradually increased, posing a serious threat to human health, marine ecosystems and economic development. For early warning, a method is required that can quickly detect and monitor microalgae. It is proposed to use aptamer targeted to Prorocentrum minimum, along with exonuclease III (Exo III), gold nanoparticles, target single-stranded DNA and hairpin structure probe to construct a new method, i.e. aptamer-lateral flow dipstick (LFD) based on Exo III-assisted signal amplification assay (ALBEA). The key conditions, including signal amplification and LFD detection, are optimized. Under the optimal conditions, the detection limit of ALBEA was 1.25 cells mL⁻¹. The cross-reactivity test showed no positive result except for P. minimum, indicating that the method is highly specific. The anti-interference test confirmed that the technique was not affected by the presence of other microalgae. The tested results of P. minimum cultured under different nutrient conditions and different growth stages demonstrated that the method is not affected by the cell state. Furthermore, the test results of simulated natural water samples further validated the practicality of the ALBEA. In conclusion, the established ALBEA offers a sensitive, specific and user-friendly tool, which can be used for the rapid detection of P. minimum and also provides a reference for the detection of other microalgae.