Marine Biotechnology最新文献

Fibroblast growth factor binding proteins (FGF-BPs) are involved in bone formation by binding to FGFs and modulating FGF signaling in vertebrates. Herein, a novel shell matrix protein gene, HcN13, was identified from the mussels Hyriopsis cumingii. Sequence analysis indicated that HcN13 belongs to the FGF-BP1 family. Quantitative real-time PCR and in situ hybridization analysis showed that HcN13 is expressed in the dorsal epithelial cells of the mantle center, indicating that HcN13 is a shell nacreous layer matrix protein. The expression of HcN13 in the mantle significantly increased during the regeneration of the prismatic and nacreous layers. Furthermore, the suppression of HcN13 at both the transcriptional and protein levels resulted in the complete destruction of the prisms and nacre tablets in vivo. However, the addition of SUMO-HcN13 did not affect the polymorphism and morphology of the crystals in vitro. These results indicated that HcN13 may serve as a modulator that influences downstream signaling pathways to further regulate shell formation. Additionally, HcN13 was highly expressed in hemocytes during pearl nacre disorder deposition and was also highly expressed in the mantle during pearl nacre order deposition, indicating that HcN13 is essential for pearl biomineralization. This study demonstrates, for the first time, the presence of FGF-BPs in the mollusk shell, highlighting their essential role in biomineralization in invertebrates.

Vibrio proteolyticus DCF12.2 has demonstrated its ability to be used as a probiotic for fish species. This study investigates how different culture conditions influence the activity of its extracellular products (ECPs) in aquaculture, focusing on enzymatic and antibacterial activity, cytotoxicity, biofilm modulation, short-chain fatty acid (SCFA) profiles, and effects on Photobacterium damselae subsp. piscicida virulence. Enzymatic assays showed a variety of hydrolytic activities, including amylase, caseinase, and collagenase, which can enhance digestion and nutrient absorption in fish. Antibacterial assays revealed that ECPs from V. proteolyticus grown in an experimental aquafeed and a partial replacement of that aquafeed by 25% of a blend of microalgae inhibited P. damselae subsp. piscicida and P. damselae subsp. damselae. Cytotoxicity assays indicated variable effects across fish cell lines, with increased viability in SAF-1 and DLB-1 cells under specific conditions, and decreased viability in PLHC-1 cells, suggesting potential antitumor properties. Biofilm assays showed that certain ECP conditions reduced biofilm formation by Vibrio anguillarum, Aeromonas hydrophila, and Tenacibaculum maritimum. SCFA profiling detected acetic, iso-valeric, butyric, and valeric acids, which may contribute to antimicrobial activity and gut health. The ECPs significantly downregulated aip56 gene transcription, reducing the virulence of P. damselae subsp. piscicida. These findings suggest that ECPs from V. proteolyticus could be valuable aquafeed additives for enhancing fish nutrition, health, and disease resistance. Future research should aim to isolate and characterize the specific bioactive compounds responsible for these effects and elucidate their mechanisms of action for optimized application in aquaculture and other biotechnological fields.

Autophagy is a cellular recycling process degrading and reusing cytoplasmic components via lysosomes or vacuoles, whereas lipophagy is a specialized form of autophagy that degrades lipid droplets (LDs). Thraustochytrids are heterotrophic marine protists known for high polyunsaturated fatty acid (PUFA) production and as valuable models for lipid metabolism research. In this study, LD degradation in Aurantiochytrium limacinum mh0186 was characterized under glucose-starvation conditions. Glucose starvation robustly activated autophagy, evidenced by GFP-tagged autophagy-related protein 8 (Atg8) translocation into endosome-like vesicles. These vesicles engulfed LDs in a microautophagy-like process, later fusing with acidic vacuole-like organelles (VLOs) to facilitate LD degradation. Impaired autophagy inhibited LD degradation in endosome-like vesicles but triggered compensatory lipolysis through elevation of intracellular lipase activity, resulting in a significant decrease in triacylglycerol (TG) levels. Our findings revealed a dual regulatory network in which autophagy orchestrated LD degradation via endosome-like vesicles, whereas autophagy inhibition triggered compensatory lipolysis activation to sustain lipid degradation.

DUSP1 is a representative member of the dual-specificity protein phosphatase family known to dephosphorylate MAPK family members and is crucial in the biosynthesis of proinflammatory cytokines. In mammals, DUSP1 is also involved in various functions including proliferation, differentiation, and apoptosis. However, little is known about the function and mechanism of DUSP1 regulating antibacterial immune response in teleost. MicroRNAs (miRNAs) have emerged as essential regulators with profound effects on immune and inflammation responses, but in teleost, the miRNA-mediated regulatory networks at different levels of signaling pathways remain largely unknown. In this study, the regulatory mechanism of the miR-200b-DUSP1-mediated inflammatory responses in teleost was addressed. We found that the expression of DUSP1 could be significantly regulated by Vibrio harveyi and lipopolysaccharide in Sciaenops ocellatus. Overexpression of DUSP1 resulted in the suppression of proinflammatory cytokine expression and cell proliferation, indicating that DUSP1 acts as a negative regulator in inflammatory responses. Furthermore, we found that miR-200b is a post-transcriptional regulator of DUSP1 that is highly expressed upon bacterial infections. Bacteria-induced miR-200b promoted cell proliferation and inflammatory responses through targeting S. ocellatus DUSP1 and increasing NF-κB signaling pathway. These results suggest that miR-200b plays a key role in promoting antibacterial immune responses through directly targeting the immune regulatory molecule DUSP1, which will greatly enrich the networks of host–pathogen interactions in lower vertebrates.

This study evaluated the effects of dietary vitamin D₃ (VD₃) levels on growth, lipid metabolism, antioxidant capacity, digestive enzyme activity, histomorphology and ammonia stress resistance in Pacific white shrimp (Penaeus vannamei) post-larvae. Shrimp were fed eight diets containing 0.2, 30.6, 74.0, 164, 278, 553, 1,128 and 2,491 μg/kg of VD₃ for 34 days. Shrimp fed VD164 and VD278 diets exhibited significantly higher growth, feed efficiency and ammonia stress resistance compared to the control (P < 0.05). Carapace calcium levels increased in shrimp fed VD₃ ≥ 30.6 μg/kg, and phosphorus in those fed ≥ 278 μg/kg (P < 0.05). Trypsin and lipase activities were elevated in all VD₃ groups except VD2491 group (P < 0.05). Superoxide dismutase, catalase and glutathione peroxidase activities were higher in VD278 and VD553 groups compared to the control (P < 0.05). Histological analysis revealed increased B and F cell counts, and reduced lipid droplets in the hepatopancreas of all VD₃ groups (P < 0.05). Midgut villi were significantly longer in all VD₃ groups, except VD30.6, and muscle thickness increased in all treatment groups (P < 0.05). VD278 upregulated expression of vitamin D receptor and genes related to lipid metabolism, indicating enhanced lipid utilization. A quadratic-plateau regression model estimated the optimal dietary VD₃ level for weight gain at 186.03 μg/kg. In conclusion, dietary VD₃ supplementation enhances growth, feed efficiency and ammonia stress resistance in P. vannamei by enhancing digestive enzyme activity, antioxidant capacity, lipid metabolism and tissue morphology.

The sea urchin Mesocentrotus nudus holds significant economic importance, making a comprehensive understanding of its sex differentiation and development mechanisms crucial for facilitating genetic enhancement. In this study, a high-quality chromosome-level assembly of the M. nudus genome was accomplished, spanning 707 Mb and encompassing 21 chromosomes, which together represented 97.6% of the assembly. Analysis of the locations of sex-linked markers indicated that sex determination in M. nudus may be predominantly governed by a confined region on chromosome 7. Within this specific area, an initial screening identified 37 protein-coding genes, encompassing 64 transcripts. Subsequent comparative transcriptome analysis revealed notable differences in the expression patterns of 11 genes (comprising 12 transcripts) between the testes and ovaries of M. nudus. In conclusion, this genome assembly serves as an invaluable resource for future investigations into the population genetics, evolutionary history, and genetic mechanism analysis of M. nudus. Moreover, the identification of the genomic location of the sex-linked region in M. nudus, coupled with the identification of candidate sex-determining genes, lends further credence to the notion of rapid evolution in sex-determining mechanisms among sea urchins.

Seaweeds, particularly those from the genus Ulva, have gained increasing attention due to their health benefits for humans and their promising bioactive properties, which are applicable as pharmaceuticals and nutraceuticals. However, the potential of Ulva species from the Adriatic Sea (Boka Kotorska Bay) remains largely unexploited. This study aimed to optimize the extraction protocol for key bioactive compounds to maximize their utilization. The chemical composition, physicochemical characteristics, antioxidant capacity, and antimicrobial properties of Ulva spp. were evaluated. Dried seaweed contained 108.51 mg GAE/100 g of polyphenolics, along with chlorophyll a (19.57 mg/100 g) and chlorophyll b (24.02 mg/100 g) as natural green pigments. The antioxidant activity, assessed by DPPH, RP, and ABTS assays, exhibited the IC50 values of 1.727, 1.167, and 0.932 mg/mL, respectively. However, the antimicrobial activity against pathogens such as S. aureus, B. cereus, E. coli, and P. aeruginosa demonstrated low potency. FTIR analysis revealed various significant peaks of characteristic alcoholic and phenolic functional groups, indicating the presence of major phytochemical compounds, while thermal analysis confirmed the good stability of the dried macroalga up to 142 °C. Among the tested extraction methods, maceration (50% ethanol, 1:20 solid-to-solvent ratio) proved to be the most effective. Dried Ulva powder demonstrated a balanced n-6/n-3 ratio and a comprehensive profile of essential and non-essential amino acids beneficial for human nutrition. All of these findings support the potential of Ulva as a valuable marine resource, promoting and contributing to the development of sustainable seaweed-based industries.

Asparagopsis taxiformis is a seaweed of interest for use as a livestock feed ingredient because of its high bromoform content, effectively reducing methane emissions from ruminants. A reliable protocol covering hatchery and nursery phases is essential to develop aquaculture techniques for gametophytes. The aim of this study was to establish a seedling production method for gametophytes under controlled laboratory conditions. We conducted the following: (1) induction of tetraspore release, (2) assessment of juvenile gametophyte growth, and (3) evaluation of gametophyte quality through bromoform quantification. Tetraspore release was successfully induced at 25 °C under an equinox photoperiod (12 h light: 12 h dark) or at 20 °C under short photoperiod (8 h light: 16 h dark), with initial spore release occurring after 12.3 ± 1.03 and 15.1 ± 1.26 days, respectively. Germinated tetraspores developed into 3–5 cm gametophytes over 2 months through static culture, followed by an aeration phase using natural seawater. Artificial seawater failed to promote gametophyte growth. Aeration improved the daily growth rate (6.86 ± 0.36%) compared to that of the static culture (4.72 ± 0.51%). Further cultivation promoted the development of main axes, lateral branches, and rhizomes. Bromoform was predominantly accumulated in the lateral branches (17.8 ± 12.3 mg·g⁻¹ dry weight (DW)) and rhizomes (12.2 ± 1.37 mg·g⁻¹ DW), compared to main axes (5.27 ± 1.95 mg·g⁻¹ DW). Unlike tetrasporophytes, which constantly released bromoforms into the medium, gametophytes maintained stable extracellular bromoform levels. These findings demonstrate a feasible approach for laboratory-scale production of A. taxiformis gametophytes with consistent bromoform accumulation, contributing to the advancement of its aquaculture.

The decreased fecundity and irregular oogenesis are commonly observed in triploid animals. However, in triploid Pacific oysters (Crassostrea gigas), females exhibit variability in reproductive capacity, with some producing abundant oocytes while others are largely infertile. Currently, the molecular mechanisms underlying these differences in triploid oysters remain poorly understood. This study investigates the role of the Sox2 transcription factor in oyster oogenesis and reproductive development. Quantitative PCR (qPCR) and in situ hybridization analysis revealed that Sox2 expression was markedly higher in the gonads of diploid females but significantly reduced in triploid females, suggesting a potential association between diminished Sox2 levels and impaired oogenesis in triploids. To test this hypothesis, RNA interference (RNAi) was used to knock down Sox2 expression in female diploids. Knockdown of Sox2 resulted in impaired gonadal development, disrupted oogenesis, and the appearance of abnormal germ cells resembling the β gonia observed in triploids. However, Sox2 knockdown did not induce apoptosis in the diploid gonadal tissue. Transcriptomic analysis revealed downregulation of genes involved in cell cycle regulation, DNA replication and repair in Sox2 knockdown C. gigas. Immunofluorescence staining of DNA damage markers showed elevated γH2AX levels in the gonads of Sox2 knockdown oysters, indicating that decreased Sox2 expression might result in defective DNA repair in germ cells of C. gigas. This study provides new insights into the molecular mechanisms underlying the sterility of triploid animals.

Gracilariopsis lemaneiformis, as an economically important red alga, often suffers high-temperature stress which poses a threat to algal yield and even survival. It is important to achieve new varieties with stable traits and heat tolerance; hence, research on the discovery and functional analysis of high-temperature responsive genes of G. lemaneiformis is significant. MYB (v-myb avian myeloblastosis viral oncogene homolog) gene family is one of the largest transcription factor superfamilies in eukaryotes and has been proved to regulate multiple environmental stresses. However, the identification and comprehensive analysis of the MYB gene family in G. lemaneiformis has rarely been studied. In this study, we identified 18 MYB genes in G. lemaneiformis at the genome-wide level, including 15 1R-MYB/MYB-related, 2 R2R3-MYB, and 1 R1R2R3-MYB members. Among them, GlMYB3, GlMYB4, GlMYB8, GlMYB9, and GlMYB15 were remarkably induced under high temperature and were also upregulated by salicylic acid, methyl jasmonate, or abscisic acid. GlMYB3, GlMYB4, GlMYB9, and GlMYB15 were localized in the nucleus when transiently expressed in Nicotiana benthamiana plants. GlMYB4, as one of the most strongly induced high temperature-associated genes, showed transactivation activity, and the C-terminal was critical for the transactivation activity. By yeast two-hybrid screening, GlMYB4 may interact with three candidate proteins: calcineurin subunit B (CNB), O-linked N-acetylglucosamine transferase (OGT), and cleavage and polyadenylation specificity factor (CPSF) to modulate high temperature tolerance.