The Pacific abalone, Haliotis discus hannai, is the most important cultivated abalone in China. Improving abalone muscle growth and increasing the rate of growth are important genetic improvement programs in this industry. MicroRNAs are important small noncoding RNA molecules that regulate post-transcription gene expression. However, no miRNAs have been reported to regulate muscle growth in H. discus hannai. we profiled six small RNA libraries for three large abalone individuals (L_HD group) and three small individuals (S_HD group) using RNA sequencing technology. A total of 205 miRNAs, including 200 novel and 5 known miRNAs, were identified. In the L_HD group, 3 miRNAs were up-regulated and 7 were down-regulated compared to the S_HD specimens. Bioinformatics analysis of miRNA target genes revealed that miRNAs participated in the regulation of cellular metabolic processes, the regulation of biological processes, the Wnt signaling pathway, ECM-receptor interaction, and the MAPK signaling pathway, which are associated with regulating growth. Bone morphogenetic protein 7 (BMP7) was verified as a target gene of hdh-miR-1984 by a luciferase reporter assay and we examined the expression pattern in different developmental stages. This is the first study to demonstrate that miRNAs are related to the muscle growth of H. discus hannai. This information could be used to study the mechanisms of abalone muscle growth. These DE-miRNAs may be useful as molecular markers for functional genomics and breeding research in abalone and closely related species.

The abalone Haliotis discus hannai is an important aquaculture species that is grown for human consumption. However, little is known of the genetic mechanisms governing muscle growth in this species, particularly with respect to proteomics. The isobaric tag for relative and absolute quantitation (iTRAQ) method allows for sensitive and accurate protein quantification. Our study was the first to use iTRAQ-based quantitative proteomics to investigate muscle growth regulation in H. discus hannai. Among the 1904 proteins identified from six samples, 125 proteins were differentially expressed in large specimens of H. discus hannai as compared to small specimens. In the large specimens, 47 proteins were upregulated and 78 were downregulated. Many of the significant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including these differentially expressed proteins, were closely related to muscle growth, including apoptosis, thyroid hormone signaling, regulation of the actin cytoskeleton, and viral myocarditis (p < 0.05). Our quantitative real-time polymerase chain reaction (qRT-PCR) analyses suggested that the alterations in expression levels observed in the differentially expressed proteins were consistent with the alterations observed in the encoding mRNAs, indicating the repeatability of our proteomic approach. Our findings contribute to the knowledge of the molecular mechanisms of muscle growth in H. discus hannai.

Most fouling organisms have planktonic larval and benthic adult stages. Larval settlement, the planktonic–benthic transition, is the critical point when biofouling begins. However, our understanding of the molecular mechanisms of larval settlement is limited. In our previous studies, we identified that the AMP-activated protein kinase-silk gland factor 1 (AMPK-SGF1) pathway was involved in triggering the larval settlement in the fouling mussel M. sallei. In this study, to further confirm the pivotal role of SGF1, multiple targeted binding compounds of SGF1 were obtained using high-throughput virtual screening. It was found that the targeted binding compounds, such as NAD⁺ and atorvastatin, could significantly induce and inhibit the larval settlement, respectively. Furthermore, the qRT-PCR showed that the expression of the foot proteins’ genes was significantly increased after the exposure to 10 μM NAD⁺, while the gene expression was significantly suppressed after the exposure to 10 μM atorvastatin. Additionally, the production of the byssus threads of the adults was significantly increased after the exposure to 10–20 μM of NAD⁺, while the production of the byssus threads was significantly decreased after the exposure to 10–50 μM of atorvastatin. This work will deepen our understanding of SGF1 in triggering the larval settlement in mussels and will provide insights into the potential targets for developing novel antifouling agents.