Abstract
A substantial proportion of Acanthopagrus schlegelii individuals change sex from male to female during their lifetime. However, the mechanisms underlying sex change are unknown. In this research, iTRAQ analyses of proteins obtained from A. schlegelii gonads in four different stages of development were compared. In total, 4692 proteins were identified, including common sex-specific proteins, such as sperm-associated antigen 6 and cilia- and flagella-associated proteins in males, and zona pellucida sperm-binding proteins in females. Furthermore, proteins involved in the integrin signaling pathway, inflammation mediated by the chemokine and cytokine signaling pathways, pyruvate metabolism, CCKR signaling map, de novo purine biosynthesis and the ubiquitin proteasome pathway were upregulated in female gonads, whereas proteins implicated in DNA replication, the heterotrimeric G-protein signaling pathway, Gi alpha- and Gs alpha-mediated pathways, wnt signaling pathway, and hedgehog signaling pathway were upregulated in male gonads. Interestingly, cathepsins were only identified in ovaries, indicating their potential involvement in rapid ovarian development. Apoptosis-related proteins expressed in ovaries (such as MAPK and Cdc42) may protect them from cancer. This is the first report on the gonad proteome from A. schlegelii in different stages of sex reversal, and the results provide important fundamental data for studying the molecular mechanisms of sex reversal.
Highlights
The evolution of sex determination is an important scientific issue in evolutionary biology
There are three types of hermaphroditism: protogyny, in which some or all individuals function first as females and later in life function exclusively as males; protandry, in which the sex change is from male to female; and simultaneous hermaphroditism, in which individuals function at the same time of life as both male and female [2]
Since half-smooth tongue sole has both a genetic sex determination and an environmental sex determination, they suggest a causal link between the bias sex chromosome and the transgenerational epigenetic inheritance of sex reversal in tongue sole fish
Summary
The evolution of sex determination is an important scientific issue in evolutionary biology. Vitellogenic oocytes did not appear in the ovary until the complete regression of testicular tissue This sex pattern provides a very good model to study the mechanism of sex change in fish. Recent research about sex reversal has identified a number of candidate sex-determining genes in various fish [13,14,15,16], such as sf-1, dmrt, dax-1, amh, wnt, foxl and cyp19a1a These genes were associated with testicular and ovarian development [17]. The compared results from each group were used to explore which proteins play the key role in the gonadal development, especially to examine the protein mechanism of sex reversal in the black porgy. The understanding of fish sex reversal mechanisms helps us to understand the evolution and development of fish reproductive strategies and the process of vertebrate sex determination
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