A Mucin-Like Protein Is Essential for Oviposition in Nilaparvata lugens

Abstract

Mucins play a variety of roles; for example, in vertebrates, mucins lubricate epithelial surfaces and protect tissue from physical and biological damage, however, knowledge of insect mucins is limited. Here, we identified an eggshell-related mucin-like protein, NlESMuc, in the brown planthopper (BPH), Nilaparvata lugens . NlESMuc was specifically expressed in the follicular cells from the egg chambers of the ovarioles. RNA interference (RNAi) was used to perform functional analysis of NlESMuc . Adult female BPH with NlESMuc knockdown had significantly reduced fecundity, including more difficult oviposition, lower egg production, and eggs that could not hatch. Scanning electron microscopy showed that, in NlESMuc knocked-down BPH, the ultrastructure of the eggshells of fully developed oocytes was loose, and the cross-section showed many small droplets of about 0.1-μm diameter. Based on the results, it is concluded that NlESMuc is an eggshell-related protein and essential for normal oviposition. Our findings help to provide new targets for pesticide design and RNAi-based BPH control and will also provide new insights into insect eggshells and insect mucins.

Identification of mucins and their expression in the vector mosquitoAedes albopictus

“…Although mammalian mucins have been extensively characterized, insect mucins remain largely unknown (Lou et al 2019). Identifying insect mucins by homology search with mammalian mucins could barely work, because of poor sequence conservation (Lang et al 2004).…”

“…Interestingly, while transcriptional upregulation of the mucin genes in the fat body and ovary is significant, transcriptional regulation of mucins in the midgut is relatively minor. Previous studies showed that the mucin-like protein of Nilaparvata lugens is essential for oviposition (Lou et al 2019), suggesting that some mosquito mucins might have effects on mosquito egg formation and oviposition. One possible explanation for the minor transcriptional regulation of mosquito midgut mucins is that the mucins might be regulated at the translational level or post-translational level.…”

“…While vertebrate mucins are well‐characterized, mucins of insects remain largely unknown. Studies have found that mucins affect insect embryonic development (Syed et al 2008), oviposition (Lou et al 2019), feeding (Shangguan et al 2018), and host cellular immunity (Hu et al 2014). Mosquitoes, which constitute a major group of disease vectors worldwide, acquire and transmit hundreds of human pathogenic viruses, including dengue virus, Zika virus, and Japanese encephalitis virus, via blood feeding (Wu et al 2019a).…”

Structural and proteomic analyses of vitelline membrane proteins of blackbird (Turdus merula) and song thrush (Turdus philomelos)

“…In general, the zona pellucida proteins consist of three or four glycoproteins (ZP1-4) with different functions during oogenesis, fertilization, and early embryonic stage. It is believed that oligosaccharides of these glycoproteins play a key role in the recognition of sperm 34 . In this study, zona pellucida glycoprotein 1 (U3KC80 FICAL) was also identified in the VM of blackbird eggs.…”

NADPH Oxidase 5 Is Essential for Molting and Oviposition in a Rice Planthopper Nilaparvata lugens

“…In N. lugens , some progress has been made in understanding its reproductive regulation mechanisms. A mucin-like gene and an eggshell-associated NlChP38 gene, specifically expressed in the follicular cells, are essential for N. lugens oviposition [ 5 , 6 ]. We speculate that there are functional candidate genes contributing to oviposition success, but which remain unexplored.…”