Mannino M Constanza, Rivarola Máximo, Scannapieco Alejandra C, González Sergio, Farber Marisa, Cladera Jorge L, Lanzavecchia Silvia B
Laboratorio de Insectos de Importancia Económica, Instituto de Genética Ewald A. Favret, Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina.
BMC Genomics. 2016 Oct 12;17(1):793. doi: 10.1186/s12864-016-2759-2.
Diachasmimorpha longicaudata (Hymenoptera: Braconidae) is a solitary parasitoid of Tephritidae (Diptera) fruit flies of economic importance currently being mass-reared in bio-factories and successfully used worldwide. A peculiar biological aspect of Hymenoptera is its haplo-diploid life cycle, where females (diploid) develop from fertilized eggs and males (haploid) from unfertilized eggs. Diploid males were described in many species and recently evidenced in D. longicaudata by mean of inbreeding studies. Sex determination in this parasitoid is based on the Complementary Sex Determination (CSD) system, with alleles from at least one locus involved in early steps of this pathway. Since limited information is available about genetics of this parasitoid species, a deeper analysis on D. longicaudata's genomics is required to provide molecular tools for achieving a more cost effective production under artificial rearing conditions.
We report here the first transcriptome analysis of male-larvae, adult females and adult males of D. longicaudata using 454-pyrosequencing. A total of 469766 reads were analyzed and 8483 high-quality isotigs were assembled. After functional annotation, a total of 51686 unigenes were produced, from which, 7021 isotigs and 20227 singletons had at least one BLAST hit against the NCBI non-redundant protein database. A preliminary comparison of adult female and male evidenced that 98 transcripts showed differential expression profiles, with at least a 10-fold difference. Among the functionally annotated transcripts we detected four sequences potentially involved in sex determination and three homologues to two known genes involved in the sex determination cascade. Finally, a total of 4674SimpleSequence Repeats (SSRs) were in silico identified and characterized.
The information obtained here will significantly contribute to the development of D. longicaudata functional genomics, genetics and population-based genome studies. Thousands of new microsatellite markers were identified as toolkits for population genetics analysis. The transcriptome characterized here is the starting point to elucidate the molecular bases of the sex determination mechanism in this species.
长尾潜蝇茧蜂（膜翅目：茧蜂科）是实蝇科（双翅目）具有经济重要性的果蝇的一种独居寄生蜂，目前在生物工厂中大量饲养并在全球范围内成功应用。膜翅目一个独特的生物学特征是其单倍体 - 二倍体生命周期，其中雌性（二倍体）由受精卵发育而来，雄性（单倍体）由未受精卵发育而来。许多物种中都有二倍体雄性的描述，最近通过近亲繁殖研究在长尾潜蝇茧蜂中得到证实。这种寄生蜂的性别决定基于互补性别决定（CSD）系统，至少一个位点的等位基因参与该途径的早期步骤。由于关于这种寄生蜂物种的遗传学信息有限，需要对长尾潜蝇茧蜂的基因组学进行更深入的分析，以提供分子工具，以便在人工饲养条件下实现更具成本效益的生产。
我们在此报告使用454焦磷酸测序对长尾潜蝇茧蜂的雄性幼虫、成年雌性和成年雄性进行的首次转录组分析。共分析了469766条读数，并组装了8483个高质量的isotig。经过功能注释，共产生了51686个单基因，其中7021个isotig和20227个单拷贝序列至少有一个与NCBI非冗余蛋白质数据库的BLAST匹配。成年雌性和雄性的初步比较表明，98个转录本显示出差异表达谱，差异至少为10倍。在功能注释的转录本中，我们检测到四个可能参与性别决定的序列以及与性别决定级联反应中两个已知基因同源的三个序列。最后，通过计算机分析鉴定并表征了总共4674个简单序列重复（SSR）。
此处获得的信息将极大地有助于长尾潜蝇茧蜂功能基因组学、遗传学和基于群体的基因组研究的发展。数千个新的微卫星标记被鉴定为群体遗传学分析的工具包。此处表征的转录组是阐明该物种性别决定机制分子基础的起点。
