Timing Sexual Differentiation: Full Functional Sex Reversal Achieved Through Silencing of a Single Insulin-Like Gene in the Prawn, Macrobrachium rosenbergii1

Abstract

In Crustacea, an early evolutionary group (∼50 000 species) inhabiting most ecological niches, sex differentiation is regulated by a male-specific androgenic gland (AG). The identification of AG-specific insulin-like factors (IAGs) and genomic sex markers offers an opportunity for a deeper understanding of the sexual differentiation mechanism in crustaceans and other arthropods. Here, we report, to our knowledge, the first full and functional sex reversal of male freshwater prawns (Macrobrachium rosenbergii) through the silencing of a single IAG-encoding gene. These "neofemales" produced all-male progeny, as proven by sex-specific genomic markers. This finding offers an insight regarding the biology and evolution of sex differentiation regulation, with a novel perspective for the evolution of insulin-like peptides. Our results demonstrate how temporal intervention with a key regulating gene induces a determinative, extreme phenotypic shift. Our results also carry tremendous ecological and commercial implications. Invasive and pest crustacean species represent genuine concerns worldwide without an apparent solution. Such efforts might, therefore, benefit from sexual manipulations, as has been successfully realized with other arthropods. Commercially, such manipulation would be significant in sexually dimorphic cultured species, allowing the use of nonbreeding, monosex populations while dramatically increasing yield and possibly minimizing the invasion of exotic cultured species into the environment.

Genomic cloning, expression, and single nucleotide polymorphism association analysis of the insulin-like androgenic gland hormone gene in the oriental river prawn (Macrobrachium nipponense)

“…qRT-PCR showed that IAG was present at low levels in the hepatopancreas, similar to results from C. sapidus (Chung et al, 2011) and F. chinensis (Ventura et al, 2012). However, this result also differed from a previous report (Ma et al, 2013).…”

“…The reduced growth of Mr-IAG-silenced individuals implied that Mr-IAG may act as a growth regulator (Ventura et al, 2009). Further study has shown that the IAG gene is closely related to metabolism in M. rosenbergii (Ventura et al, 2012). IAG may, thus, represent an excellent positional and functional candidate gene for growth traits in crustaceans.…”

Molecular cloning and expression analysis of two sex-lethal homolog genes during development in the oriental river prawn, Macrobrachium nipponense

“…To understand the mechanism controlling sex maturation, a high-quality normalized cDNA library from testis tissue of this species has been established (Qiao et al, 2012). For this reason, molecular mechanisms regulating the expression of sex-specific and sex-determining genes in crustaceans have received great attention in recent years Kato et al, 2011;Ventura et al, 2012). In the present study, we aimed to obtain a full cDNA clone encoding the Sxl gene from the cDNA library of testis in M. nipponense, and to examine the expression pattern of the Sxl gene during the embryonic development, larvae, and post-larvae stages of M. nipponense.…”

A crayfish molar tooth protein with putative mineralized exoskeletal chitinous matrix c properties

“…Furthermore, in vivo silencing of Cq-M15 was lethal, suggesting it has a vital function during the molt cycle. While numerous gene- silencing studies assessing the functionality of novel crustacean genes have been published previously (Ventura et al, 2009(Ventura et al, , 2012Rosen et al, 2010), to the best of our knowledge, the lethal effect of gene silencing has been previously reported in crustaceans only once (Christoffersen et al, 1989). We had shown earlier that silencing of particular transcripts in C. quadricarinatus affects the formation of the extracellular matrix and the calcification process (Shechter et al, 2008b;Glazer et al, 2010), as well as the duration of molt cycles (Pamuru et al, 2012;Tynyakov et al, 2015).…”