Identification of a female spawn‐associated Kazal‐type inhibitor from the tropical abalone Haliotis asinina

Abstract

Abalone (Haliotis) undergoes a period of reproductive maturation, followed by the synchronous release of gametes, called broadcast spawning. Field and laboratory studies have shown that the tropical species Haliotis asinina undergoes a two-week spawning cycle, thus providing an excellent opportunity to investigate the presence of endogenous spawning-associated peptides. In female H. asinina, we have isolated a peptide (5145 Da) whose relative abundance in hemolymph increases substantially just prior to spawning and is still detected using reverse-phase high-performance liquid chromatography chromatograms up to 1-day post-spawn. We have isolated this peptide from female hemolymph as well as samples prepared from the gravid female gonad, and demonstrated through comparative sequence analysis that it contains features characteristic of Kazal-type proteinase inhibitors (KPIs). Has-KPI is expressed specifically within the gonad of adult females. A recombinant Has-KPI was generated using a yeast expression system. The recombinant Has-KPI does not induce premature spawning of female H. asinina when administered intramuscularly. However it displays homomeric aggregations and interaction with at least one mollusc-type neuropeptide (LRDFVamide), suggesting a role for it in regulating neuropeptide endocrine communication. This research provides new understanding of a peptide that can regulate reproductive processes in female abalone, which has the potential to lead to the development of greater control over abalone spawning. The findings also highlight the need to further explore abalone reproduction to clearly define a role for novel spawning-associated peptide in sexual maturation and spawning. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Alternative Splicing Profile and Sex-Preferential Gene Expression in the Female and Male Pacific Abalone Haliotis discus hannai

“…Genes involved in numerous metabolic pathways such as innate immunity, cell stress and repair system, and antioxidant defense systems have been cloned and tested to determine their mRNA expression, translational inducibility, and molecular functions. Recently, the use of a genomics platform was successfully applied in H. discus hannai , although many research groups have continuously employed ‘-omics’ platforms (e.g., genomics, proteomics, linkage map development, Bacterial Artificial Chromosome (BAC) library construction) to understand the growth, development, reproduction, molecular adaptation, or innate immune response mechanisms upon environmental stressors or pathogen challenges in the Haliotis genus [5,6,7,8,9,10,11,12,13,14]. For H. discus hannai , a genetic linkage map was constructed as a potential application of marker-assisted selection in breeding programs using amplified fragment length polymorphism (AFLP) markers [15].…”

Neural Ganglia Transcriptome and Peptidome Associated with Sexual Maturation in Female Pacific Abalone (Haliotis discus hannai)

“…Recently, transcriptome and proteome analyses of abalone have been conducted to identify the reproductive and metabolic genes, such as vitellogenin, forkhead box protein L2, sperm-associated antigen 6, Fem-1 homolog C-like, Teckin-1, heat shock cognate 70, and peroxiredoxin 6 [22,23]. In addition, the putative abalone neuropeptides that were involved in the regulation of sexual maturation and spawning were reported, including GnRH [24], a Kazal-type proteinase inhibitor [25], APGWamide [26,27], myomodulin, whitnin, FMRFamide, a schistosomin-like peptide, molluscan insulin-related peptide, and haliotid growth-associated peptide [14]. However, the detailed mechanisms that orchestrate the entire reproductive process have not yet been elucidated, and no systematic identification of neuropeptides that are involved in sexual maturation has been performed in abalone species.…”