Masculinizer is not post-transcriptionally regulated by female-specific piRNAs during sex determination in the Asian corn borer, Ostrinia furnacalis. (May 2023)

• Record Type: Journal Article
• Authors: Fukui, Takahiro; Shoji, Keisuke; Kiuchi, Takashi; Suzuki, Yutaka; Katsuma, Susumu
• Is Part Of: Insect biochemistry and molecular biology. Volume 156(2023)
• Publication Date: 2023-05
• Subjects: Lepidoptera -- Ostrinia furnacalis -- Sex determination -- Masculinizer -- PIWI-interacting RNA -- doublesex; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2023.103946
• Languages: English
• ISSNs: 0965-1748

Abstract

Abstract: Lepidopteran insects are heterogametic in females, although most insect species are heterogametic in males. In a lepidopteran model species, the silkworm Bombyx mori (Bombycoidea), the uppermost sex determinant Feminizer ( Fem ) has been identified on the female-specific W chromosome. Fem is a precursor of PIWI-interacting small RNA (piRNA). Fem piRNA forms a complex with Siwi, one of the two B . mori PIWI-clade Argonaute proteins. In female embryos, Fem piRNA–Siwi complex cleaves the mRNA of the male-determining gene Masculinizer ( Masc ), directing the female-determining pathway. In male embryos, Masc activates the male-determining pathway in the absence of Fem piRNA. Recently, W chromosome-derived piRNAs complementary to Masc mRNA have also been identified in the diamondback moth Plutella xylostella (Yponomeutoidea), indicating the convergent evolution of piRNA-dependent sex determination in Lepidoptera. Here, we show that this is not the case in the Asian corn borer, Ostrinia furnacalis (Pyraloidea). Although our previous studies demonstrated that O . furnacalis Masc ( OfMasc ) has a masculinizing function in the embryonic stage, the expression level of OfMasc was indistinguishable between the sexes at the timing of sex determination. Deep sequencing analysis identified no female-specific small RNAs mapped onto OfMasc mRNA. Embryonic knockdown of two PIWI genes did not affect the expression level of OfMasc in either sex. These results demonstrated that piRNA-dependent reduction of Masc mRNA in female embryos is not a common strategy of sex determination, which suggests the possibility of divergent evolution of sex determinants across the order Lepidoptera. Graphical abstract: Image 1 Highlights: The embryonic mRNA level of Masculinizer ( Masc ) was similar between the sexes in Ostrinia furnacalis . Small RNA-seq failed to identify Masc -targeting piRNAs in Ostrinia furnacalis. Knockdown of PIWI genes did not affect the mRNA level of Masc in either sex. Sex determination by Masc -targeting piRNAs is not a common system among Lepidoptera.