Geuverink E, Verhulst E C, van Leussen M, van de Zande L, Beukeboom L W
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
Insect Mol Biol. 2018 Feb;27(1):99-109. doi: 10.1111/imb.12352. Epub 2017 Oct 14.
In many insect species maternal provision of sex-specifically spliced messenger RNA (mRNA) of sex determination genes is an essential component of the sex determination mechanism. In haplodiploid Hymenoptera, maternal provision in combination with genomic imprinting has been shown for the parasitoid Nasonia vitripennis, known as maternal effect genomic imprinting sex determination (MEGISD). Here, we characterize the sex determination cascade of Asobara tabida, another hymenopteran parasitoid. We show the presence of the conserved sex determination genes doublesex (dsx), transformer (tra) and transformer-2 (tra2) orthologues in As. tabida. Of these, At-dsx and At-tra are sex-specifically spliced, indicating a conserved function in sex determination. At-tra and At-tra2 mRNA is maternally provided to embryos but, in contrast to most studied insects, As. tabida females transmit a non-sex-specific splice form of At-tra mRNA to the eggs. In this respect, As. tabida sex determination differs from the MEGISD mechanism. How the paternal genome can induce female development in the absence of maternal provision of sex-specifically spliced mRNA remains an open question. Our study reports a hitherto unknown variant of maternal effect sex determination and accentuates the diversity of insect sex determination mechanisms.
在许多昆虫物种中，母体提供性别决定基因的性别特异性剪接信使核糖核酸（mRNA）是性别决定机制的一个重要组成部分。在单双倍体膜翅目昆虫中，寄生蜂丽蝇蛹集金小蜂已证明母体提供与基因组印记相结合，即所谓的母体效应基因组印记性别决定（MEGISD）。在此，我们描述了另一种膜翅目寄生蜂烟蚜茧蜂的性别决定级联反应。我们展示了烟蚜茧蜂中存在保守的性别决定基因双性基因（dsx）、变异性别决定因子（tra）和变异性别决定因子2（tra2）的直系同源基因。其中，At-dsx和At-tra进行性别特异性剪接，表明在性别决定中具有保守功能。At-tra和At-tra2 mRNA由母体提供给胚胎，但与大多数已研究的昆虫不同，烟蚜茧蜂雌虫向卵中传递的是At-tra mRNA的非性别特异性剪接形式。在这方面，烟蚜茧蜂的性别决定不同于MEGISD机制。在没有母体提供性别特异性剪接mRNA的情况下，父本基因组如何诱导雌性发育仍是一个悬而未决的问题。我们的研究报告了一种迄今为止未知的母体效应性别决定变体，并突出了昆虫性别决定机制的多样性。
