Sexual dimorphic expression pattern of a splice variant of zebrafish vasa during gonadal development

Abstract

In Drosophila, the RNA helicase VASA (VAS) is required for both germ line formation and oocyte differentiation. While the murine VAS homologue is required for spermatogenesis, it is dispensable for germ line formation. The molecular basis for this apparently dual role of VAS in germ line ontogeny is, however, unclear. Recent evidence indicates that fish, like flies, employs VAS both in early and late stages of the germ line development and that there is a sex-linked differential expression of splice variants. We show here that the longer of two splice variants of zebrafish vas is transiently downregulated in the germ line around the time when the germ cells reach the developing gonad. Using transgenic vas::EGFP fish lines, which allow us to distinguish between male and female individuals, we show that the long splice variant reappears in both sexes at around day 25 and is subsequently downregulated during male gonadal development. Our data further suggest that there is a switch from maternal to zygotic expression of the long splice variant of vas as sexual dimorphic development commences.

Identification and sexually dimorphic expression of vasa isoforms in Dabry′s sturgeon (Acipenser dabryanus), and functional analysis of vasa 3′-untranslated region

“…Additionally, sexual dimorphic expression of vasa variants has also been reported. Zebrafish had long and short isoforms of vasa in the ovary, and only short transcript in the testis (Krovel and Olsen 2004), while the rare minnow had long and short variants of vasa in the testis, and only a long variant in the ovary (Cao et al 2012). In tilapia, vas and vas-s variants were both detected in the ovary and the testis, with vas mainly expressed in the testis and vas-s abundant in the ovary (Kobayashi et al 2002).…”

“…Different isoforms of Vasa homologues have also been identified in other fish. Two vasa variants were found in tilapia (Kobayashi et al 2002), zebrafish (Krovel and Olsen 2004) and the rare minnow (Cao et al 2012), while more than two transcripts were characterized in Senegalese sole (Pacchiarini et al 2013), Japanese flounder (Wu et al 2014b), tongue sole and Lusitanian toadfish (UbedaManzanaro et al 2014). Most isoforms from each species displayed slight sequence differences at the N-terminus.…”

Heat-induced masculinization in domesticated zebrafish is family-specific and yields a set of different gonadal transcriptomes

“…The AB zebrafish strain and the Tg(vasa:vasa-egfp) zebrafish line of AB strain (78) were used for the temperature treatment experiments. Breeding protocols and husbandry details can be found in SI Appendix, Materials and Methods.…”

Cloning and characterization of Vasa gene expression pattern in adults of the Lusitanian toadfish Halobatrachus didactylus

“…In this sense, it was thought that Vasa expression in fish was restricted to germ cell lineage, however Vasa extragonadal expression has been reported in several fish species, such as Onco rhynchus mykiss (Yoshizaki et al 2000), Dicentrarchus labrax (Blázquez et al 2011) and Solea senegalensis (Pacchiarini et al 2013b). Many studies have reported levels and pattern changes of Vasa expression during embryogenesis, sex differentiation and larval development in various fish species (Yoon et al 1997, Krøvel & Olsen 2004, Xu et al 2005, Li et al 2010, Raghuveer & Senthilkumaran 2010, Cao et al 2012, Lin et al 2012, Pacchiarini et al 2013a, showing a differential expression during oogenesis and spermatogenesis (Cao et al 2012). Different Vasa transcripts with different expression patterns have also been characterized in diverse fish species, such as zebrafish, tilapia and Senegalese sole (Yoon et al 1997, Kobayashi et al 2002, Pacchiarini et al 2013b, and the Vasa gene is usually present as a single copy gene in the majority of chordates, e.g.…”

“…Different Vasa transcripts with different expression patterns have also been characterized in diverse fish species, such as zebrafish, tilapia and Senegalese sole (Yoon et al 1997, Kobayashi et al 2002, Pacchiarini et al 2013b, and the Vasa gene is usually present as a single copy gene in the majority of chordates, e.g. in zebrafish (Krøvel & Olsen 2004). However, recently, Fujimura et al (2011) re ported 3 Vasa gene loci in the genome of tilapia.…”