Analysis of ovarian transcriptomes reveals thousands of novel genes in the insect vectorRhodnius prolixus

Abstract

Rhodnius prolixus is a Triatominae insect species and a primary vector of Chagas disease. The genome of ​ R. prolixus has been recently sequenced and partially assembled, but few transcriptome analyses have been performed to date. In this study, we describe the stage-specific transcriptomes obtained from previtellogenic stages of oogenesis and from mature eggs. By analyzing ~228 million paired-end RNA-Seq reads, we significantly improved the current genome annotations for 9,206 genes. We provide extended 5' and 3' UTRs, complete Open Reading Frames, and alternative transcript variants. Strikingly, using a combination of genome-guided and de novo transcriptome assembly we found more than two thousand novel genes, thus increasing the number of genes in ​ R. prolixus ​ from 15,738 to 17,864. We used the improved transcriptome to investigate stage-specific gene expression profiles during ​ R. prolixus oogenesis. Our data reveal that 11,127 genes are expressed in the early previtellogenic stage of oogenesis and their transcripts are deposited in the developing egg including key factors regulating germline development, genome integrity, and the maternal-zygotic transition. In addition, GO term analyses show that transcripts encoding components of the steroid hormone receptor pathway, cytoskeleton, and intracellular signaling are abundant in the mature eggs, where they likely control early embryonic development upon fertilization. Our results significantly improve the ​ R. prolixus genome and transcriptome and provide novel insight into oogenesis and early embryogenesis in this medically relevant insect.

Knockdown of E1‐ and E2‐ubiquitin enzymes triggers defective chorion biogenesis and modulation of autophagy‐related genes in the follicle cells of the vector Rhodnius prolixus

“…To identify the ovary‐expressing genes involved in the conjugation of ubiquitin to targeted substrates, we explored the stage‐specific transcriptome obtained from the previtellogenic follicles and chorionated oocytes of R. prolixus (Coelho et al, 2021). We designed specific primers for the mRNAs encoding pUbq (RPRC012247), E1‐activating (RPRC003935), and the two most abundant E2‐conjugating enzymes in the oocyte's transcriptomes E2.1 (RPRC007710) and E2.2 (RPRC006315).…”

“…The sequences of R. prolixus pUbq (RPRC012247), E1 (RPRC003935), E2.1 (RPRC007710), and E2.2 (RPRC006315) were first retrieved from transcriptomes obtained from R. prolixus chorionated oocytes (Coelho et al, 2021), and validated using the genome and transcriptome databases (Rpro C3.2) available in Vector Base (http://www.vectorbase.org; Giraldo‐Calderón et al, 2015; Mesquita et al, 2015).…”

eIF3 subunit M regulates blood meal digestion in Rhodnius prolixus affecting ecdysis, reproduction and survival

“…The eIF3m subunit is conserved from fission yeast to higher eukaryotes, but it is absent in budding yeast (Zeng et al, 2013), and it is the only unidentified eIF3 subunit in trypanosomatid genomes (Rezende et al, 2014). After sequencing the R. prolixus genome, the first triatomine genome available (Mesquita et al, 2015), several transcriptomic studies appeared correlating mRNA level profiles of different tissues with physiology, immunity, reproduction and development (Coelho et al, 2021; Latorre-Estivalis et al, 2020, 2017; Leyria et al, 2020a, 2020b; Ribeiro et al, 2014). However, the results obtained with a proteomic approach in the midgut showed an expression profile distinct from the mRNA, suggesting that post-transcriptional regulation of gene expression is crucial (Ouali et al, 2021).…”

Global characterization of gene expression in the brain of starved immature R. prolixus

“…Transcriptomic studies allowed the discovery of new genes and transcripts, the identification of differentially expressed genes, determining targets for broader functional analyses. Some transcriptomes have analyzed gene expression in different R. prolixus tissues such as salivary glands (27), ovaries (28,29), gut (25), testicles (30), and antennae (22). Furthermore, this technique allowed defining the molecular bases of female reproductive physiology under differing nutritional states (18), as well as characterizing the innate immune system of these bugs at the molecular level (31).…”

“…Furthermore, this technique allowed defining the molecular bases of female reproductive physiology under differing nutritional states (18), as well as characterizing the innate immune system of these bugs at the molecular level (31). Several of these bioinformatic analyses have recently shown that the genome of R. prolixus has many missing or miss-annotated genes (22,29,31), highlighting the importance of transcriptomes for improving the quality of the annotated genome of R. prolixus . Therefore, the present study aims to describe the genetic components that serve as the molecular neural bases controlling behavior in the brain of unfed R. prolixus nymphs.…”