Marine Biotechnology最新文献

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.

Reproductive traits are of paramount importance as economic traits in shrimps, playing a vital role in enhancing commercial larval production within the aquaculture industry. Identifying genetic markers associated with reproductive traits is essential for implementing genomic and marker-assisted selection strategies to enhance reproductive performance. However, the existing knowledge of such genetic markers in Exopalaemon carinicauda remains relatively limited. In this study, we utilized next-generation sequencing coupled with bulked segregant analysis to identify molecular markers and candidate genes associated with reproductive traits in E. carinicauda using a F₂ population. A total of 31,048,793 SNPs and 3193 indels were identified between the two pools. Six candidate regions, spanning 72.24 Mb on chromosomes 6, 14, 15, 21, 23, and 35, were consistently identified through Euclidean distance and ΔSNP-index analyses, encompassing 609 genes. Kyoto Encyclopedia of Genes and Genomes analysis revealed significant associations with pathways such as ovarian steroidogenesis, oocyte meiosis, insulin signaling, GnRH signaling, and estrogen signaling. Among these, 22 genes showed strong links to ovarian development based on comparative transcriptomic analysis across 4 ovarian development stages. The integrated analysis of whole genome and transcriptome data showed that four genes (juvenile hormone esterase carboxylesterase, aurora kinase A, insulin-like peptide receptor, and Argonaute 3) might play important roles in regulating reproductive traits of E. carinicauda. Five SNP loci were validated employing a general linear model that are significantly associated with fecundity traits in the F₂ population. These findings not only offer valuable insights into the genetic underpinnings of reproductive traits but also provide a strong foundation for the development of genomic and marker-assisted selection strategies aimed at enhancing fecundity traits in E. carinicauda.

The aims of this study were to investigate marker-growth trait associations and construct a SNP-based linkage map for an Asian seabass (KU) population from Thailand. First, we performed GWAS using phenotypes (weight and length) and genotypes (25,647 SNPs) for 1100 390-day-old fish. We selected the top 70 SNPs with allele substitution effects, ranging from 6.84 to 81.91 g for weight and from 0.12 to 1.8 cm for length for further analyses. Cross-validation of 70 SNPs using GBLUP yielded breeding value prediction accuracies 0.65 to 0.70. Second, we utilized previously published genome-wide SNPs and mapping data from multiple populations and the KU data to predict the genetic linkage map for the KU population using the Marey map approach. The KU linkage map consisted of 24 chromosomes spanning 567 Mb, with average marker spacing of 0.07 cM. The number of markers ranged from 598 to 1334, with an average of 1099 markers per chromosome. The predicted local recombination rates varied from 4.76 to 43.40 cM/Mb with an average of 2.35 cM/Mb. Lastly, Kompetitive allele-specific PCR (KASP) markers were developed from 70 SNPs and validated in 200 fish. The KASP assays were successful for all 70 SNPs in 196 fish with SNP call rates of 98.2 to 100%. Fifty-eight SNPs were found to have segregated across the genome, except for chromosomes 23 and 24. The linkage map obtained in this study provides a framework for future QTL mapping of growth-related traits in the KU population.

The crustacean hyperglycemic hormone (CHH) family is a group of key neuroendocrine regulators of molting, metabolism, and reproduction in crustaceans. Litopenaeus vannamei, the most widely farmed shrimp, exhibits pronounced sexual growth dimorphism, yet the role of CHH family genes in this process remains poorly understood. Here, we identified an ion transport peptide-like (ITP-like) gene in L. vannamei, and demonstrated its male-biased expression and sexually dimorphic functions. The ITP-like gene was predominantly expressed in eyestalks, with significantly higher levels in males than females, suggesting its role in sex-specific physiological regulation. Functional experiments using RNA interference (RNAi) and recombinant protein injection revealed its divergent and sex-dependent roles: ITP-like knockdown enhanced male growth but reduced female growth, while recombinant ITP-like protein showed opposing effects. Transcriptomic analysis of eyestalks identified differentially expressed genes linked to digestive enzymes, cuticle formation, lipid metabolism, and phototransduction, revealing a complex regulatory network underpinning the sexually dimorphic effects of ITP-like. Our findings demonstrate that ITP-like influences shrimp growth by modulating metabolic pathways, molting processes and photoreceptive responses, providing new insights into crustacean endocrine regulation. This study advances understanding of the mechanisms underlying sex-biased growth in L. vannamei and highlights potential targets for aquaculture improvement.

Host defense peptides (HDPs) are vital to immunity due to their antimicrobial and immunomodulatory properties. While extensively studied in mammals, their immunomodulatory roles remain complex, and research on HDPs in fish is limited. This study aimed to predict physicochemical properties and mechanisms of action of seven HDPs in gilthead seabream (Sparus aurata): two piscidins (piscidin 1, piscidin 2) and five hepcidins (hepcidin H1, H2C, H2E, H2H, H2I). Predictions indicated heterogeneity among HDPs, all exhibiting antioxidant capacity and bioactive potential. In vitro analyses of these synthetic HDPs on head kidney leucocytes of gilthead seabream revealed minimal direct effects on leucocyte activities. RT-PCR gene expression analysis in leukocytes after 2 h of HDP incubation showed significant upregulation of bax-1 (hepcidin H2I), il-6 (piscidin 2), tnf-α (piscidin 1), tlr-7 (piscidin 1), and tlr-8 (piscidin 1), and downregulation of casp-3 (hepcidin H1), bcl-2 (hepcidin H2C), il-1β (hepcidin H1, H2C, H2E, H2H, H2I), tnf-α (piscidin 2, hepcidin H1, H2E, H2I), tlr-7 (piscidin 2, hepcidin H2E), and tlr-8 (piscidin 2, hepcidin H2H). The results indicate that HDPs demonstrate diverse immunomodulatory impacts on seabream white blood cells, playing a crucial role in regulating genes associated with programmed cell death, inflammatory responses, and Toll-like receptors. This complex function highlights the adaptability and significance of the studied HDPs in the immune system of gilthead seabream.