Marine Biotechnology最新文献

The microalgae Euglena holds promise for biofuel production due to its high lipid content. However, the lipid productivity of current species/strains for biofuel production remains suboptimal due to limitations in strain selection. Therefore, this study aims to isolate and identify novel Euglena species or strains with high biomass and lipid productivity to enhance biofuel production from a desirable environment. Malaysia’s tropical climate with abundant sunlight and water resources provides an ideal environment for microalgae cultivation. Therefore, this research is conducted in Malaysia for effective utilization. Accordingly, water samples were collected from various Raja Musa Forest Reserve habitats in Selangor, Malaysia including peatland, paddy fields and the Kuala Selangor River. The samples were isolated using the single-cell pickup technique. The isolated samples were cultivated using the test tube system. The biomass and lipid productivity were quantified using the gravimetric technique. The top novel lipid-producing Euglena strain SAB-3 was identified through scanning light microscopy and phylogenetic analysis of the ITS2 region. The Sab-3 was placed within the Euglena gracilis clade through this analysis, showing close similarity to the E. gracilis SAG strain. SAB-3 dominated high biomass productivity (0.704  g L¹ day¹), high lipid productivity (0.051 g L¹ day¹) and relatively high specific growth rate (1.091 day¹) with a shorter cultivation time of 7 days compared to the E. gracilis (NIES-48).

With few preventive strategies available against nodavirus (NNV) in aquaculture, therapeutic applications remain underexplored. This study aimed to peptide-based treatments disrupting critical stages of its viral life cycle. Thus, we designed and synthesized seven low-molecular-weight peptides (P1–P7) based on predicted binding regions of the capsid protein from the red-spotted grouper nervous necrosis virus (RGNNV) genotype to mimic viral capsid regions. Although in silico predictions suggested limited direct antiviral activity, in vitro assays using the E-11 cell line and in vivo trials in RGNNV-infected European sea bass (Dicentrarchus labrax) juveniles yielded promising results. The peptides, particularly when co-administered individually or as P3 + P4 and P5 + P6 combinations with the virus, disrupted RGNNV attachment in vitro. Moreover, they exhibited cross-reactivity against the striped jack nervous necrosis virus (SJNNV) genotype and both RGNNV/SJNNV and SJNNV/RGNNV reassortants. Treatment of RGNNV-infected sea bass significantly increased the relative percent survival, ranging from 81.3% for P4 to 62.5% for P3 and P3 + P4, while reducing viral load within 48 h post-treatment without altering systemic antiviral immune responses, tested through the transcriptional levels of mx gene in the head-kidney. Notably, peptide P4 partially inhibited viral replication in vitro at the same time-point when cells were pre-treated for 24 h, likely through modulation of host immune responses. These findings highlight the potential of targeted peptide-based therapies as a promising antiviral therapeutic strategy against NNV infections.

Growth differentiation factor 9 (GDF9) is a member of the transforming growth factor-β (TGF-β) superfamily and is expressed in an oocyte-specific manner. It plays a crucial role in the early stage of ovarian development. Japanese eel (Anguilla Japonica), a spawning migration teleost, has artificial reproduction still under investigation. Aimed at developing a novel method for the successful artificial reproduction of Japanese eel, in the present study, the role of GDF9 in the regulation of early ovarian development was investigated. The Gdf9 gene in Japanese eel was 1293 bp in length, coding for 430 amino acids. Expression analysis in different tissues showed that gdf9 is highly expressed in the ovary, and the gdf9 mRNAs are localized in early developmental oocytes. Injection experiments showed that GDF9 significantly increased the gonadosomatic index in Japanese eel. However, histological observations indicated that GDF9 injection alone was insufficient to overcome the cortical alveolus stage and initiate vitellogenesis in Japanese eel, which is consistent with the lack of significant changes in serum estradiol and vitellogenin levels. Transcriptomic analysis revealed that GDF9 is involved in various molecular functions and physiological processes within the ovary. Overall, our findings suggest that GDF9 plays a regulatory role in the early ovarian development of Japanese eel, possibly by promoting the formation and activation of primordial follicles. These findings offer novel evidence for understanding the regulation of early ovarian development in Japanese eel and provide a valuable foundation for advancing artificial breeding in this species.

Shrimp maturation is governed by the hormones secreted by neurosecretory structures in the eyestalk known as X-organ sinus gland complex (XOSG). The X-organ consists of a cluster of neurosecretory cells responsible for synthesizing crustacean hyperglycemic family hormones, including crustacean hyperglycemic hormone (CHH), molt inhibiting hormone (MIH), and gonad inhibiting hormone (GIH). CHH family neuropeptides have gained attention for three decades due to their endocrinological role in aquaculture. One of the most challenging tools in crustacean endocrinology research was the unavailability of a crustacean cell line. Recently, a novel hybrid cell line, the PmLyO-Sf9, was developed by fusing Penaeus monodon lymphoid organ cells with Sf9 cells. Focusing on this cell line, we undertook a comprehensive analysis of the transcriptional and translational expression profiling of CHH/MIH/GIH neuropeptides in the PmLyO-Sf9. In the transcriptional expression studies, the cDNA-based gene profiling of CHH (235 bp), MIH (243 bp), and GIH (247 bp) was determined. A comparative gene expression of CHH/MIH/GIH in PmLyO-Sf9 cell line and Lymphoid organ in Penaeus monodon revealed consistent expression in both. Immunofluorescence confirmed the translational expression of CHH/MIH/GIH with immune-positive cells exhibiting neuropeptides localized in the cytoplasm of PmLyO-Sf9 cells. This is the first study that proved the presence of CHH family neuropeptides in PmLyO-Sf9 cell line and in the Lymphoid organ of Penaeus monodon, hitherto not reported. Accordingly, the cell line has been identified as a suitable platform for endocrinological expression, with potential applications in lieu of animal model.

To elucidate the molecular mechanisms by which grass carp respond to high-concentration NaHCO₃ stress, this study employed RNA-sequencing technology to perform transcriptome analysis on the gill and liver tissues of the treatment group with 30 mmol/L NaHCO₃ and the control group (0 mmol/L). Through sequencing of 12 libraries constructed from 6 gill samples and 6 liver samples, a total of 41.86 GB of high-quality data from gill tissues and 41.49 GB of high-quality data from liver tissues were obtained. The analysis revealed that there were 1223 and 439 significantly differentially expressed genes (DEGs) in the gill and liver tissues, respectively, under NaHCO₃ stress. Functional enrichment (GO) analysis indicated that grass carp respond to alkaline stress by regulating biological processes such as protein hydrolysis, ATP-binding activity, and lipid metabolism. Pathway (KEGG) analysis further revealed that immune-related signaling pathways were significantly activated to resist external stress, and the elevation of energy metabolism levels may provide necessary support for the stress-resistance process. This study systematically revealed the molecular adaptation strategies of grass carp in a high-alkali environment, providing an important theoretical basis for the molecular breeding of saline-alkali-tolerant grass carp varieties and the research on stress-resistance mechanisms.

This study aimed to assess the potential of a gene delivery technique in the red macroalga Pyropia yezoensis (Rhodophyta) using electroporation without removing the cell wall. An antibiotic resistance gene was introduced into P. yezoensis tissues containing cells with intact cell walls through electroporation, followed by selection with the corresponding antibiotic. No germlings survived in the non-electroporated control tissue fragments under antibiotic selection. In contrast, some germlings were observed to survive in the electroporated group. Furthermore, the presence of antibiotic resistance genes was confirmed in the genomic DNA of several antibiotic-resistant germlings. Although reporter genes such as β-glucuronidase (GUS) and green fluorescent protein (GFP) were also introduced as supplementary markers, their expression was not detectable under the tested conditions. These findings provide evidence supporting the successful introduction of antibiotic resistance genes into P. yezoensis cells via electroporation. This study offers a preliminary assessment of a gene delivery strategy in P. yezoensis that bypasses cell wall removal, presenting a straightforward method for introducing foreign genes into Pyropia. To the best of our knowledge, this is the first report to demonstrate successful gene transfer via electroporation in a macroalga without cell wall removal. These results provide valuable insights for the development of genetic transformation systems in red macroalgae.

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.