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One of the major challenges in the aquaculture of marine organisms is the susceptibility to pathogens. Immune cells defend bacterial invasion by recognizing pathogen-associated molecular patterns (PAMPs) such as Lipopolysaccharides (LPS) in Gram-negative bacteria. The white body are key organs for immune response and hematopoiesis, and play an important role in understanding the antimicrobial biological response in gold-ringed octopus (Amphioctopus fangsiao). In the present research, transcriptome sequencing and bioinformatics analysis were conducted on A. fangsiao white body tissue after 6 h and 24 h of LPS stimulation. The results showed 2,029 and 73 differentially expressed genes (DEGs) at the 6- and 24-hour time points, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were beneficial in determining immune-related terms and signaling pathways. Subsequently, a protein-protein interaction (PPI) network was constructed and 20 hub genes, such as AKT3, MAPK14, and PIK3CA, were identified. These genes are involved in a variety of signaling pathways, including the Hippo signaling pathway, chemokine signaling pathway, and leukocyte trans endothelial migration. Using qRT-PCR, the accuracy of the 20 hub genes was verified. The present study provides a substantial theoretical foundation for the research on A. fangsiao white body immunity, enhancing the current understanding of cephalopods' innate immunity.

Sepia esculenta is a tasty and nutritious cephalopod. But the trend toward global warming is accelerating with massive emissions of greenhouse gases. An increase in seawater temperature and a decrease in pH are a great challenge for artificial breeding and culture of S. esculenta. In this study, we investigated the contingency mechanism of S. esculenta larvae under both high temperature and low pH conditions by transcriptome analysis. A total of 1235 DEGs were identified. functional enrichment analysis results suggest that high temperature and low pH conditions led to malignant proliferation in exceptional cells of S. esculenta larvae. A comprehensive analysis of the KEGG signaling pathway and protein-protein interaction network (PPI) identified sixteen key genes under both high temperature and low pH conditions. The three genes with the highest quantities of interactions or involved in more KEGG signaling pathways were identified as hub genes affecting normal physiological processes in S. esculenta. In this study, the effects of global warming and ocean acidification on the metabolism and immunity of S. esculenta larvae were preliminarily investigated to provide necessary help for S. esculenta captive breeding in the face of global climate change.

Marine mollusks, including oysters, are highly tolerant to high levels of cadmium (Cd), but the molecular mechanisms underlying their molecular response to acute Cd exposure remain unclear. In this study, the Pacific oyster Crassostrea gigas was used as a biological model, exposed to acute Cd stress for 96 h. Transcriptomic analyses of their gills were performed, and metabolomic analyses further validated these results. In our study, a total of 111 differentially expressed metabolites (DEMs) and 2108 differentially expressed genes (DEGs) were identified under acute Cd exposure. Further analyses revealed alterations in key genes and metabolic pathways associated with heavy metal stress response. Cd exposure triggered physiological and metabolic responses in oysters, including enhanced oxidative stress and disturbances in energy metabolism, and these changes revealed the biological response of oysters to acute Cd stress. Moreover, oysters could effectively enhance the tolerance and detoxification ability to acute Cd exposure through activating ABC transporters, enhancing glutathione metabolism and sulfur relay system in gill cells, and regulating energy metabolism. This study reveals the molecular mechanism of acute Cd stress in oysters and explores the molecular mechanism of high tolerance to Cd in oysters by using combined metabolomics and transcriptome analysis.

Near-infrared spectroscopy (NIR) has become an essential tool for non-destructive analysis in various fields, including aquaculture. This study presents a pioneering application of portable NIR spectrometers to analyze glycogen content in the gonadal tissues of the Pacific oyster (Crassostrea gigas), marking the first instance of developing quantitative models for glycogen in tetraploid C. gigas. The research also provides a comparative analysis with models for diploid and triploid oysters, underscoring the innovative use of portable NIR technology in aquaculture. Two portable NIR spectrometers were employed: the Micro NIR 1700 (908–1676 nm) and the Micro PHAZIR RX (1624–2460 nm). Near-infrared spectra were acquired from the gonadal tissues of diploid, triploid, and tetraploid C. gigas. Quantitative models for glycogen content were developed and validated using cross-validation methods. Additionally, qualitative models for different ploidies and genders were established. For the Micro NIR 1700, the cross-validation correlation coefficients (Rcv) and cross-validation relative predictive errors (RPDcv) for glycogen were 0.949 and 3.191 for diploids, 0.915 and 2.498 for triploids, and 0.902 and 2.310 for tetraploids. The Micro PHAZIR RX achieved Rcv and RPDcv values of 0.781 and 2.240 for diploids, 0.839 and 2.504 for triploids, and 0.717 and 1.851 for tetraploids. The Micro NIR 1700 demonstrated superior quantitative performance, with RPD values exceeding 2, indicating its effectiveness in predicting glycogen content across different ploidy levels. Qualitative models showed a performance index of 91.6 for diploid and 95 for tetraploid genders using the Micro NIR 1700, while the Micro PHAZIR RX achieved correct identification rates of 99.79% and 100% for diploid and tetraploid genders, respectively. However, differentiation of ploidies was less successful with both instruments. This study’s originality lies in establishing the first quantitative models for glycogen content in tetraploid C. gigas using portable NIR spectrometers, highlighting the significant advancements in non-destructive glycogen analysis. The applicability of these findings is substantial for oyster breeding programs focused on enhancing meat quality traits. These models provide a valuable phenotyping tool for selecting oysters with optimal glycogen content, demonstrating the practical utility of portable NIR technology in aquaculture.

Over the years, oysters have faced recurring mass mortality issues during the summer breeding season, with Vibrio infection emerging as a significant contributing factor. Tubules of gill filaments were confirmed to be in the hematopoietic position in Crassostrea gigas, which produce hemocytes with immune defense capabilities. Additionally, the epithelial cells of oyster gills produce immune effectors to defend against pathogens. In light of this, we performed a transcriptome analysis of gill tissues obtained from C. gigas infected with Vibrio alginolyticus for 12 h and 48 h. Through this analysis, we identified 1024 differentially expressed genes (DEGs) at 12 h post-injection and 1079 DEGs at 48 h post-injection. Enrichment analysis of these DEGs revealed a significant association with immune-related Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. To further investigate the immune response, we constructed a protein–protein interaction (PPI) network using the DEGs enriched in immune-associated KEGG pathways. This network provided insights into the interactions and relationships among these genes, shedding light on the underlying mechanisms of the innate immune defense mechanism in oyster gills. To ensure the accuracy of our findings, we validated 16 key genes using quantitative RT-PCR. Overall, this study represents the first exploration of the innate immune defense mechanism in oyster gills using a PPI network approach. The findings provide valuable insights for future research on oyster pathogen control and the development of oysters with enhanced antimicrobial resistance.

The emergence of triploid oysters has freed the oyster market from the problem of interruptions in the breeding season, allowing for year-round availability. However, according to recent statistics, the phenomenon of fertility in triploid oysters has been increasing yearly, perhaps eventually leading to the loss of the sterility characteristic. This has in turn affected the oyster farming industry. Therefore, we attempted to mine key genes through transcriptomics to find the causes of triploid fertility. During our surveys and sampling, we found that most of the fertile triploid Crassostrea gigas were females, with a much smaller percentage of males. Therefore, the main objective of this study was to analyze the differences between fertile and sterile triploid female C. gigas. We performed transcriptome analysis of fertile female triploid C. gigas and sterile female triploid C. gigas and identified 2361 up-regulated differentially expressed genes (DEGs) and 1541 down-regulated DEGs, respectively. Enrichment analysis of these DEGs revealed that most GO terms and KEGG pathways were associated with mitosis. We then created a protein–protein interaction (PPI) network using genes enriched in mitosis-associated KEGG pathways. Finally, we screened and validated 26 key genes by quantitative RT-PCR and all were found to be downregulated in expression in sterile female triploids. The main cause of sterility is the suppression of the expression of genes that control the process of germ cell proliferation, the failure of the mitotic cycle to proceed smoothly, and the inability to produce an oogonium. These results can be used to explore ways to reduce the fertility of triploid C. gigas and to promote the breeding of higher quality triploid oysters.

Sargassum golden tides have bloomed frequently in many sea areas throughout the world, and negatively impacted on the local marine ecology. Sargassum muticum commonly inhabits rocky shores. It is now distributed worldwide due to its invasiveness, and recently drifting individuals have been observed on the coasts of Canary Islands. However, as a potential golden tide alga, physiological, and ecological studies of this species have not been frequently explored. To investigate the responses of S. muticum to light and nitrogen, two key environmental factors in golden tide formation, we established three light levels (LL, low light, 10 μmol photons m–2 s–1; ML, medium light, 60 μmol photons m–2 s–1, and HL, high light, 300 μmol photons m–2 s–1) and two nitrogen levels (LN, low nitrogen, 25.0 μM of natural seawater; HN, high nitrogen, 125.0 μM), and cultivated the thalli under different conditions for 12 days before measuring the physiological properties of alga. The results showed that higher light and/or nitrogen levels enhanced the relative algal growth rate. The maximum net photosynthesis rate of alga increased with the light, while it remained unaffected by the nitrogen. The HN treatment had no effect on the apparent photosynthetic efficiency of algae in the LL culture, while increased it in the ML and HL cultures. The irradiance saturation point of photosynthesis was approximately 300 μmol photons m–2 s–1 with no significant difference among the six treatments, except for a slight increase under HLHN in contrast to the LLHN and MLLN treatments. HL treatment decreased the maximum quantum yield of photosynthesis (Fv/Fm) in both nitrogen levels. In the HN culture, ML and HL led to lower values of photoinhibition, indicating higher survivability in the alga. The HN culture led to higher nitrogen uptake but had no effects on Fv/Fm and the contents of pigments and soluble protein, regardless of culture light level. Based on these results, we speculate that drifting individuals of S. muticum would be possible to form a golden tide owing to its rapid growth rate at light level of 300 μmol photons m–2 s–1, when they encountered the sustained lower light level on the sea surface (≤300 μmol photons m–2 s–1). A high nitrogen supply caused by eutrophication of seawater might facilitate this process. Our results provide an important reference for the prediction of golden tides formed by S. muticum.

Sargassum golden tides (GT) are common in numerous coastal areas all over the world, and it adversely affects local marine life. Eutrophication is critical for Sargassum GT development. However, its physiological and ecological mechanism remains unclear. To investigate the responses of drifting Sargassum horneri, the species causing GT in the western Pacific, to light and enriched nitrogen, we set three light conditions (Low-light (LL), 10 μmol photons m−2 s−1; Middle-light (ML), 60 μmol photons m−2 s−1; and High-light (HL), 300 μmol photons m−2 s−1) and three nitrogen conditions (Natural seawater, the final concentration of N was 31.8 μmol L−1, including 30.5 μmol L−1 of NO3− and 1.3 μmol L−1 of NH4+; Enrichment of NO3−, final concentration of N was 200 μmol L−1; and Enrichment of NH4+, the final concentration of N was 200 μmol L−1), and grew the thalli under varying conditions for 10 days before determining the growth and utilization of carbon and nitrogen. Based on the accumulated data, the elevated light level led to a higher growth rate of alga. In the LL culture, the higher capacity for carbon utilization, which was reflected by the higher maximum photosynthetic carbon fixation rate (Vmax), resulted in the elevated growth rates of thalli in the nitrogen-enriched media as compared with the natural seawater. Furthermore, a higher growth rate was found in the enrichment of NH4+ despite a low affinity for inorganic carbon indicated by a higher value of the half-saturation constant (K0.5). In the ML treatment, an insignificant difference in growth rate was found in three nitrogen cultures, except for a slight increase in the enrichment of NH4+ than the enrichment of NO3−. In the HL treatment, compared with natural seawater culture, enrichment of NO3− or NH4+ accelerated the growth of alga, with no significant difference between the two nitrogen sources. Such enhancement in growth was related to the more photosynthetic carbon fixation, indicated by the higher value of Vmax and soluble carbohydrates content of alga cultured with NO3− and NH4+ enrichments. Additionally, the uptake and assimilation products of nitrogen, such as pigments and soluble proteins, remained unaffected by nitrogen source enrichment of NO3− or NH4+ at all three light levels. In conclusion, enrichment of NO3− and NH4+ exhibited different influences on the growth of S. horneri at different light levels, which was mainly associated with the capacity and efficiency of photosynthetic carbon utilization. At the HL level, both the enrichment of NO3− and NH4+ dramatically accelerate the growth of alga by stimulating the photosynthetic carbon fixation. Accordingly, we speculated that drifting S. horneri, exposed to HL level on the surface of the sea, were likely to develop rapidly to form GT in eutrophic oceanic areas with upwelled and river plume NO3− or NH4+ nutrients.

The plastids and mitochondria of the eukaryotic cell are of endosymbiotic origin. These events occurred ~2 billion years ago and produced significant changes in the genomes of the host and the endosymbiont. Previous studies demonstrated that the invasion of land affected plastids and mitochondria differently and that the paths of mitochondrial integration differed between animals and plants. Other studies examined the reasons why a set of proteins remained encoded in the organelles and were not transferred to the nuclear genome. However, our understanding of the functional relations of the transferred genes is insufficient. In this paper, we report a high-throughput phylogenetic analysis to identify genes of cyanobacterial origin for plants of different levels of complexity: Arabidopsis thaliana, Chlamydomonas reinhardtii, Physcomitrella patens, Populus trichocarpa, Selaginella moellendorffii, Sorghum bicolor, Oryza sativa, and Ostreococcus tauri. Thus, a census of cyanobacterial gene recruits and a study of their function are presented to better understand the functional aspects of plastid symbiogenesis. From algae to angiosperms, the GO terms demonstrated a gradual expansion over functionally related genes in the nuclear genome, beginning with genes related to thylakoids and photosynthesis, followed by genes involved in metabolism, and finally with regulation-related genes, primarily in angiosperms. The results demonstrate that DNA is supplied to the nuclear genome on a permanent basis with no regard to function, and only what is needed is kept, which thereby expands on the GO space along the related genes.