RNAi reveals the key role of Nervana 1 in cockroach oogenesis and embryo development

Abstract

Na+ , K + -ATPases is a heterodimer protein consisting of α-and β-subunits that control the ion transport through cell membranes . In insects the β-subunit of the Na + , K + -ATPase, known as Nervana, was characterized as a nervous system-specific glycoprotein antigen from adult Drosophila melanogaster heads. Nervana is expressed ubiquitously in all insect tissues, and in epithelial cells appeared located in a basolateral position as part of the septate junctions. Herein we study two Nervana isoforms fromBlattella germanica, a cockroach species with panoistic ovaries. The sequencing and the phylogenetic analysis results suggest that these two isoforms are orthologs of D.melanogaster Nervana 1 and Nervana 2, respectively. Nervana 1 is highly expressed in the ovary of B. germanica, and depleting its expression results in changes in oocyte shape that do not impair oviposition. However, the resulting embryos show different defects and never hatch. These findings highlight the importance of this type of membrane pump in insect oogenesis as well as in embryo development, and its possible regulation by juvenile hormone.

Knockdown of juvenile hormone acid methyl transferase severely affects the performance of Leptinotarsa decemlineata (Say) larvae and adults

“…50,51,79 In contrast, RNAi successfully knocked down target genes in several tissues in T. castaneum 80 -83 and in various developmental stages in Blattella germanica. 46,84,85 Although we do not know why our approach is so efficient, our results indicate that it will be possible in the future to develop this approach to control L. decemlineata.…”

Systemic RNAi of V‐ATPase subunit B causes molting defect and developmental abnormalities in Periplaneta fuliginosa

“…However, because RNAi efficacy is variable among insect species (e.g., RNAi experiments were unsuccessful in some studies using Lepidoptera) (Bellés, 2010;Terenius et al, 2011), consideration of the target insect species is required. Previously, RNAi was demonstrated to work well in two cockroach species, P. americana and B. germanica (Cruz et al, 2006;Pueyo et al, 2008;Gomez-Orte & Bellés, 2009;Revuelta et al, 2009;Irles et al, 2013;French et al, 2015;Lozano et al, 2015;Lemonds et al, 2016). For example, the requirement of the melanin pathway for overall body pigmentation in P. americana nymphs and adults was revealed by RNAi of two enzymecoding genes (Lemonds et al, 2016).…”

“…Functional analysis of this unique insect group is expected to greatly contribute to the comparative study of V-ATPases. Additionally, RNAi works well as a powerful reverse genetics tool in two other sanitary pest species, P. americana and B. germanica (Cruz et al, 2006;Pueyo et al, 2008;Gomez-Orte & Bellés, 2009;Revuelta et al, 2009;Irles et al, 2013;French et al, 2015;Lozano et al, 2015;Lemonds et al, 2016). Nevertheless there is no report of RNAi in P. fuliginosa, the most abundant pest cockroach species in Japan (The Japanese Society of Pestology, Personal communication).…”

Unlike in Drosophila Meroistic Ovaries, Hippo Represses Notch in Blattella germanica Panoistic Ovaries, Triggering the Mitosis-Endocycle Switch in the Follicular Cells

“…One characteristic of B. germanica oogenesis is that only the basal oocyte develops in each gonadotrophic cycle [25]. This oocyte begins maturation in the last nymphal instar, expressing most of the genes that will be necessary for its development and the formation of the future embryo [25], [26]. During the last nymphal instar the follicular epithelium that surrounds the basal oocyte shows the highest rate of proliferation, coinciding with the highest expression of the main components of the Hippo pathway.…”