Search Results (54)

Pacific abalone (Haliotis discus hannai) is a widely cultured and economically important abalone species in aquaculture yet improving growth performance remains a major challenge for stable production. To clarify the molecular architecture associated with growth performance in Pacific abalone, we integrated transcriptome and genome-wide association study (GWAS) data from high-growth and low-growth groups showing significant growth differences. Transcriptome profiles from hepatopancreas and mantle tissues were used to construct a co-expression network of 43,125 genes, summarized into 22 modules associated with tissue specificity and growth-related variation. In parallel, analysis of a custom 60K SNP array identified 67 significant growth-associated SNPs. Integration of these GWAS signals into the co-expression network revealed a core module most strongly correlated with growth index and enriched for SNP-derived candidate genes. Functional enrichment indicated that the core module was associated with proteostasis and growth-related signaling pathways, including insulin, Ras, and MAPK signaling. Protein–protein interaction analysis further identified 11 hub genes with high intramodular connectivity and direct interactions with SNP-derived genes, most of which participate in receptor-mediated and intracellular growth-regulatory functions. These findings provide an integrated molecular framework for growth performance in Pacific abalone and candidate targets for future molecular breeding strategies. Full article

This study was designed to evaluate the genetic parameters of growth, meat yield and foot color in Pacific abalone (Haliotis discus hannai) to support the development of a quality-oriented breeding program. Using data from 141 pedigreed full-sib families, heritabilities and genetic correlations among these traits were estimated. The results indicated that shell length at varying ages (0.45–0.71) and total wet weight (0.48) exhibited moderate-to-high heritabilities, suggesting substantial potential for genetic improvement in growth traits. The heritabilities for foot color (0.26) and meat weight (0.31) were moderate and statistically significant (p < 0.05), whereas the heritability for meat yield (0.14) was low and not statistically significant (p > 0.05). Strong positive genetic correlations were observed between shell length and total wet weight at harvest (0.90), as well as between total wet weight and meat weight at harvest (0.92). In contrast, the genetic correlations between total wet weight and foot color, and between total wet weight and meat yield, were low and not statistically significant (p > 0.05). These findings suggest that direct selection can effectively improve the growth and meat weight of Pacific abalone. However, improving foot color and meat yield may require independent or multi-trait selection approaches. Overall, this study provides crucial data for formulating a comprehensive breeding strategy that integrates both production efficiency and product quality in Pacific abalone aquaculture. Full article

Haliotis discus hannai meat has a firm texture that makes it difficult to chew and swallow, so tenderizing is necessary. Ultrasonic treatment and papain enzyme processing are used to reduce the hardness of abalone meat. This study tests physicochemical indicators and protein changes to assess meat quality and protein alterations. The maximum reduction in hardness of raw meat reached 60.58%, while heat-treated abalone meat achieved 61.13%, with free water and bound water converting to immobile water. The L* value of the meat decreased, while the a* and b* values increased. In raw meat, the content of TCA-soluble peptides increased with increasing treatment intensity. However, in heat-treated meat, this peptide content decreased with rising temperature. Muscle fiber filament breaks and pore numbers increased. The BPB binding content showed a negative correlation with the percentage of α-helix. Total sulfhydryl and free amino groups in raw meat decrease with increasing treatment intensity; both parameters in cooked meat decrease with rising temperature. Changes in tertiary protein structure cause alterations in fluorescence intensity, with secondary structure shifting from α-helix to β-sheet conformation. The results suggested that ultrasonic and papain treatments can induce structural alterations in proteins. This leads to protein cleavage and depolymerization, collectively resulting in softening of abalone meat texture and redistribution of internal moisture. These processes result in softening of abalone meat and redistribution of internal moisture. This study provides a theoretical basis for developing abalone tenderizers. Full article

The increasing use of water-based drilling muds in offshore oil and gas operations has raised concerns about potential ecological risks of their primary components, such as bentonite, on marine organisms. To date, the biological effects of bentonite on benthic species remain poorly understood. This study aimed to evaluate the physiological and oxidative stress responses of Pacific abalone (Haliotis discus hannai) exposed to varying concentrations (20–3000 mg/L) of bentonite over a 10-day period. Short-term exposure (up to 7 days) to bentonite did not result in significant mortality across treatment groups; however, partial mortality was observed in the highest concentration group (3000 mg/L) on day 8. Biochemical analyses revealed elevated levels of hydrogen peroxide and malondialdehyde, particularly in higher concentration groups, indicating oxidative stress. Antioxidant enzyme activities showed concentration- and time-dependent changes, with early activation followed by suppression under prolonged exposure. Total antioxidant capacity also declined over time in high-concentration groups. These findings indicate that while bentonite may not be acutely lethal to abalone, it can trigger sublethal oxidative stress responses, particularly under chronic exposure conditions, underscoring the importance of evaluating long-term physiological impacts of suspended drilling particulates and the need for research on a wider range of marine species. Full article

This study multidimensionally investigates the comprehensive effects of Lactobacillus plantarum (LP)-fermented feed on growth performance, intestinal health, and metabolic regulation in Pacific abalone (Haliotis discus hannai). The results demonstrate that LP fermentation significantly alters feed’s physical properties and nutritional profile, softening texture, increasing viscosity, and emitting an acidic aroma. Notably, it enhanced contents of cis-9-palmitoleic acid, α-linolenic acid (ALA), and functional amino acids (GABA, L-histidine, and L-asparagine), indicating that fermentation optimized ω-3 fatty acid accumulation and amino acid profiles through the modulation of fatty acid metabolic pathways, thereby improving feed biofunctionality and stress-resistant potential. Further analyses revealed that fermented feed markedly improved intestinal morphology in abalone, promoting villus integrity and upregulating tight junction proteins (ZO-1, Claudin) to reinforce intestinal barrier function. Concurrently, it downregulated inflammatory cytokines (TNF-α, NF-κB, IL-16) while upregulating anti-inflammatory factors (TLR4) and antioxidant-related genes (NRF2/KEAP1 pathway), synergistically mitigating intestinal inflammation and enhancing antioxidant capacity. Sequencing and untargeted metabolomics unveiled that fermented feed substantially remodeled gut microbiota structure, increasing Firmicutes abundance while reducing Bacteroidetes, with the notable enrichment of beneficial genera such as Mycoplasma. Metabolite profiling highlighted the significant activation of lipid metabolism, tryptophan pathway, and coenzyme A biosynthesis. A Spearman correlation analysis identified microbiota–metabolite interactions (such as Halomonas’ association with isethionic acid) potentially driving growth performance via metabolic microenvironment regulation. In conclusion, LP-fermented feed enhances abalone growth, immune response, and aquaculture efficiency through multi-dimensional synergistic mechanisms (nutritional optimization, intestinal homeostasis regulation, microbiota–metabolome crosstalk), providing critical theoretical foundations for aquafeed development and probiotic applications in aquaculture. Full article

Low-coverage whole-genome sequencing (lcWGS) followed by imputation is emerging as a cost-effective method for generating a substantial number of single nucleotide polymorphism (SNP) in aquatic species with highly heterozygous and complex genomes. This study represents the first systematic investigation into the application of low-coverage whole-genome sequencing (lcWGS) combined with imputation for genotyping in Pacific abalone (Haliotis discus hannai) without a reference panel. We utilized 1059 Pacific abalone individuals sequenced at an average depth of 7.86×, as well as 16 individuals sequenced at 20×, as sample materials. To assess the genotype imputation accuracy for lcWGS without a reference panel, we simulated data with varying sequencing depths (0.5–4×) and examined the effects of sample size, chromosome length, and minor allele frequency (MAF) using BaseVar and STITCH strategies. Results showed that STITCH achieved high accuracy when the sample size exceeded 400, with a genotype correlation (R²) of 0.98 ± 0.002 and genotype concordance (GC) of 0.99 ± 0.001. Imputation accuracy plateaued when the sample size exceeded 400 and sequencing depth surpassed 1×. Chromosome length had minimal effects, with all three chromosomes achieving an accuracy of approximately 0.98. However, the accuracy for rare MAF (<0.05) was lower, falling below 0.99. A second imputation with Beagle significantly increased SNP detection by 3.9–8.3 folds for a sequencing depth of 0.5–4×, apparently without sacrificing accuracy. To our knowledge, this is the first study of lcWGS analysis conducted in abalone. The findings demonstrate that lcWGS with imputation can achieve high accuracy with moderate sample sizes (n ≥ 400) in Pacific abalone, offering a cost-effective approach for genotyping in aquaculture species. Full article

This study analyzed the basic nutritional components and amino acid, fatty acid, and mineral composition of hybrid abalone Haliotis discus hannai ♀ × H. fulgens ♂ adductor (AM), transition (TM), and skirt (SM) muscles. The taste characteristics of the muscles were measured via electronic tongue, and the volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis. Compared to SM, AM and TM exhibited relatively similar basic nutritional compositions. Although SM exhibited the highest moisture content (84.67%), its protein content (only 11.83%) and total carbohydrate content (only 0.19%) were significantly lower than those of AM (20.42% and 4.14%) and TM (19.10% and 4.48%). The ash and fat contents were similar across the three muscle parts. The amino acid composition was consistent across three parts, and AM showed the highest total amino acid content, ratio of essential amino acids, and essential amino acid index. All three muscle parts were rich in polyunsaturated fatty acids, but the content was higher in AM and TM than in SM. The mineral elements were rich in variety, with high K, P, Mg, and Zn contents. Bitterness intensities were lower and umami and richness intensities were higher in AM and TM than in SM. The contents of volatile compounds related to fishy odor were higher in TM and SM than in AM. The results provided a scientific basis for the intensive processing and comprehensive utilization of Haliotis discus hannai ♀ × H. fulgens ♂. Full article

Reproduction and breeding are crucial to maintaining abalone aquaculture. Understanding the molecular underpinnings of sexual maturation is essential for advancing knowledge in reproductive biology. However, the molecular mechanisms of gonadal development in abalones remain poorly understood, particularly in microRNA (miRNA)-mediated regulation. Thus, this study conducted a comprehensive transcriptomic analysis of abalone Haliotis discus hannai (H. discus hannai) to identify genes and miRNAs associated with ovarian and testicular discovery. This study identified 685 differentially expressed (DE) genes between the H. discus hannai ovary (DD_ovary) and testis (DD_testis) groups, comprising 479 upregulated and 206 downregulated genes in the DD_ovary. Moreover, 137 miRNAs, including 83 novel and 54 known miRNAs, were detected, with 30 upregulated and 27 downregulated in the DD_ovary compared to the DD_testis. Bioinformatics analysis revealed that these miRNAs regulate key processes such as carbohydrate metabolic processes, kinase and hydrolase activity, and starch and sucrose metabolism, all potentially associated with reproductive traits. Further, key mRNA candidates, including Vitelline envelope sperm lysin receptor (Verl) and Testis-specific serine/threonine-protein kinase (Tssk) 1, and miRNAs such as novel_90 and novel_120, were identified as components of a functional miRNA-mRNA network associated with sexual maturity and sex determination. These key genes were verified using qRT-PCR and fluorescence in situ hybridization (FISH). These transcriptomic and miRNA datasets provide valuable resources for understanding abalone reproductive biology and may support molecular breeding strategies. Full article

Background/Objectives: Vasa and PL10 belong to the DEAD-box protein family, which plays crucial roles in various cellular functions, such as DNA replication, DNA repair, and RNA processing. Additionally, DEAD-box family genes have also been identified as being related to gonadal development in many species. However, the function of vasa and PL10 in abalone is poorly understood on a molecular level. Methods: In the present study, we individually isolated and characterized the vasa and PL10 orthologs in Haliotis discus hannai (Hdh-vasa and Hdh-PL10). We also characterized the mRNA distributions of vasa and PL10 in various tissues from adult organisms and different embryonic developmental stages using real-time PCR (RT-qPCR) techniques. Furthermore, spatial and temporal expression of Hdh-vasa and Hdh-PL10 throughout embryonic and larval development was examined by whole-mount in situ hybridization (WMISH). Results: The two predicted amino acid sequences contained all of the conserved motifs characterized by the DEAD-box family. Homology and phylogenetic analyses indicate that they belong to the vasa and PL10 subfamilies. We found that vasa and PL10 mRNA were not solely restricted to gonads but were widely expressed in various tissues. WMISH showed that Hdh-vasa and Hdh-PL10 largely overlapped, with both being maternally expressed and specifically localized to the micromere lineage cells during early cleavage stages. By the gastrulation stage, Hdh-vasa were expressed strongly in two bilaterally symmetrical paraxial clusters, but Hdh-PL10 was dispersed in entire endodermal region. Our results suggest that Hdh-vasa-expressing cells are located as a subpopulation of undifferentiated multipotent cells that express Hdh-PL10. As such, we infer that primordial germ cells are specified from these vasa-expressing cells at some point during development, and inductive signals (epigenesis) play an important role in specifying primordial germ cells (PGCs) in H. discus hannai. Conclusions: This study provides valuable insights into the molecular characteristics and expression patterns of Hdh-vasa and Hdh-PL10, contributing to a better understanding of their roles in germ cell specification and early embryonic development in H. discus hannai. Full article

Haliotid herpesvirus 1 (HAHV-1) causes significant damage to the abalone aquaculture industry. Knowledge of HAHV-1 invasion and host defense mechanisms is limited due to the lack of stable molluscan cell lines. The present study established an in vitro infection model of HAHV-1 using the primary suspension cultures of hemocytes from Haliotis diversicolor supertexta and Haliotis discus hannai. The cytopathic effects of HAHV-1 on adherent-cultured hemocytes of both species were also investigated. The HAHV-1 DNA loads were firstly monitored by means of quantitative PCR during the development of viral infection, and subsequently the mechanism of interaction between HAHV-1 and hemocytes was explored by means of a transcriptome analysis. H. diversicolor supertexta hemocytes exhibited a high degree of susceptibility to HAHV-1, with viral loads reaching a peak of 4.0 × 10⁷ copies/ng DNA. In contrast, no significant replication was observed in H. discus hannai hemocytes. Transcriptome analysis revealed that HAHV-1 evades the host immune response in the early stages of infection, and hijacks the host’s energy and redox metabolism to promote its replication at the late stages. Consequently, this study provides a valuable reference point for the investigation of virus−host interaction between HAHV-1 and abalone in vitro. Full article

Abalone is an economically important mollusk, whose slow growth has impeded the recovery of its wild populations and development of aquaculture. The three-way cross hybrid abalone ((Haliotis discus hannai♀ × H. fulgens♂)♀ × H. gigantea♂, DF × SS) demonstrated notable diversity in growth traits across the population with genetic differentiation, offering a model for exploring the molecular mechanisms of abalone growth. In this study, a total of 89 SNPs and 97 candidate genes were identified to be associated with growth-related traits of abalone using whole-genome resequencing and a genome-wide association study (GWAS) analysis. Then, ten overlap genes were found among these candidate genes by combining the results of GWAS and comparative transcriptomic analyses between the large individuals (L group) and small individuals (S group) of DF × SS. These overlap genes include up-regulated genes (fabG) and down-regulated genes (HMCN1, TLR3, ITIH3) between the L and the S groups, which are thought to function in growth in other organisms. The biological functions of these candidate genes in abalone still have to be confirmed, but they have improved our understanding of the molecular mechanisms behind abalone growth traits and provided molecular markers for abalone breeding programs. Full article

Background/Objectives: The Pacific abalone Haliotis discus hannai originated in cold waters and is an economically important aquaculture shellfish in China. Our goal was to clarify the current status of the genetic structure of Pacific abalone in China. Methods: In this study, eighteen polymorphic EST-SSR loci were successfully developed based on the hemolymph transcriptome data of Pacific abalone, and thirteen highly polymorphic EST-SSR loci were selected for the genetic variation analysis of the six populations collected. Results: The results showed that the average number of observed alleles was 8.0769 (RC)-11.3848 (DQ) in each population. The number of observed alleles in the DQ, NH, and TJ populations was significantly higher than that in the RC population. The cultivated population outside the Changshan Islands has experienced a 22.79% reduction in allele diversity compared to the wild population of DQ. The pairwise F_st values and analysis of molecular variance (AMOVA) revealed significant population differentiation among all populations except DQ and NH populations, with RC and ZZ cultured populations exhibiting the largest population differentiation (F_st = 0.1334). The phylogenetic tree and structural analysis divided the six populations into two groups (group 1: NH, DQ, and ZZ; group 2: DL, TJ, and RC), and there was no relationship between geographical distance and genetic distance. Conclusions: These results may reflect the large-scale culture from different populations in China and the exchange of juveniles between hatcheries. Different breeding conditions have led to a higher degree of genetic differentiation between the RC and ZZ populations. This study enables a better understanding of the genetic diversity and structure of current Pacific abalone populations. Full article

(1) Background: Animal growth is a complex process, involving the coordination of a wide variety of genes, non-coding RNAs, and pathways. Circular RNAs (circRNAs) belong to a novel class of functional non-coding RNAs (ncRNAs). They have a distinctive ring structure and are involved in various biological processes, including the proliferation, differentiation, and apoptosis of muscle cells. The Pacific abalone Haliotis discus hannai is an economically valuable mollusk species cultivated in China. However, the modulation of muscle growth by circRNAs in this species is poorly understood. (2) Methods: In this study, we analyzed the muscle transcriptomes of 6 H. discus hannai specimens: three small (S_HD) and three large (L_HD) groups via RNA-seq and bioinformatics technology. (3) Results: The results indicated the presence of 11,744 circRNAs in abalone adductor muscle. Furthermore, the L_HD group had 250 significantly differentially expressed circRNAs (106 upregulated and 144 downregulated) relative to the S_HD group. Moreover, the bioinformatics assessment revealed that circRNAs were related to lipid transporter activity, lipid biosynthetic process, fat digestion and absorption, the single-organism metabolic process, the thyroid hormone signaling pathway, and the hippo signaling pathway, which regulates growth. Seventeen key candidate circRNAs were identified, and a core functional circRNA-miRNA-mRNA network associated with abalone muscle growth was described. Gene expression was verified using qRT-PCR, confirming the accuracy of the RNA-seq data. (4) Conclusion: Overall, this investigation furnishes novel evidence for the potential muscle growth modulatory mechanisms in Pacific abalone. These high-quality circRNA data of abalone muscle provide a reference for functional studies on the abalone genome. Full article

Few studies are concerned with the effect of the conjugat protein on the bioactivities of the abalone gonad polysaccharide (AGP). In this study, a series of treatments, including raw material (female and male) defatting, extraction temperature (25–121 °C), proteolysis, ultrafiltration, and ethanol precipitation, was conducted to investigate the role of the conjugate protein on AGP anticoagulant activity. All AGP extracts significantly prolonged activated partial thromboplastin time (APTT) and thrombin time (TT). The strongest was observed in the female AGPs prepared at 50 and 121 °C. The most active is located at 30–300 kDa by ultrafiltration. After being exposed to neutral protease, quick shortening of APTT and TT was found in all AGPs. Further ethanol precipitating of found the longest APTT in the sediment, which contains most polysaccharides and proteins. Defatting lowered the activity of female AGP but increased that of males. Proteolysis also significantly weakened the clotting factor inhibition effect of the 50 °C female AGP, but heating seemed not affect the effect. Five fractions were obtained after the 50 °C female AGP was subjected to ion exchange column. Fraction V, with the highest protein and medium polysaccharide content, showed the strongest anticoagulant effect and was also much higher than AGSP, which was obtained by multi-step proteolysis. The findings supported positive effect of the conjugate protein in AGP anticoagulant activity. Full article

The Nrf2/ARE pathway is considered the most important endogenous antioxidant signaling pathway in mammals, playing a crucial role in defending against external damage. This study investigated the functional characteristics of Nrf2 in the abalone, Haliotis discus hannai. The full-length cDNA sequence of the HdhNrf2 gene was cloned using rapid amplification of cDNA ends (RACE) technology and consists of 4568 base pairs encoding a protein of 694 amino acids. The predicted theoretical molecular weight was 77 kDa, with an isoelectric point of 4.72. Multiple sequence alignment analysis revealed the relative conservation of the HdhNrf2 amino acid sequence in H. discus hannai. The tissue expression pattern of the HdhNrf2 gene was analyzed using real-time fluorescence quantitative PCR, which showed the highest expression in the gills, followed by hemocytes, with the lowest levels in the foot and mantle. The inducible expression of HdhNrf2 and antioxidant genes in abalone under H₂O₂ stress was investigated at various time points. Furthermore, an expression vector, pET-28a(+)-rHdhNrf2, was constructed, and the recombinant protein rHdhNrf2 was obtained through induced expression and purification. These findings indicated that HdhNrf2 plays a crucial role in the defense of abalones against oxidative stress. Full article