Regulation of vitellogenin genes in insects

Abstract

Vitellogenins (Vg) genes code for the major egg yolk protein precursor in insects and many other oviparous species. In insects, the Vg gene is expressed extra-ovarially in the fat body in sex-, tissue-and stage-specific manners. During the reproductive phase, the Vg mRNA is expressed in large quantities, which is then translated, secreted into hemolymph and ultimately taken up by the developing oocytes through receptormediated endocytosis. Once sequestered, the Vgs are stored as vitellin (Vn), the main nutritional reserve for the developing embryo. The regulation of Vg genes is directly under the control of hormones at the transcriptional level. Hormones involved in Vg gene transcription are juvenile hormone (JH), ecdysteroids and some neuropeptides. The overall understanding that has emerged is that the insects can be classified, based on the system of hormonal regulation of Vg gene transcription, into three groups: (i) insects (like most of hemipterans) that use only JH for Vg gene transcription; (ii) insects (like dipterans) that need both JH and ecdysteroids for Vg regulation; and (iii) insects like lepidopterans that require JH, ecdysteroids and additional hormones to regulate their reproductive biology. However, why insect species diverge in using different hormones to govern their reproductive physiology remains unclear. The present contribution focuses on the current status of knowledge regarding the regulation of Vg genes in insects. Besides a brief information on biochemical and molecular features, the role of Vg genes as a target of endocrine disruptors will be addressed. Also, the molecular mechanism of Vg gene regulation will be discussed.

Identification of Development-Related Genes in the Ovaries of Adult Harmonia axyridis (Pallas) Lady Beetles Using a Time- Series Analysis by RNA-seq

“…Five genes were included in the Jak-STAT signalling pathway, which can affect the bone morphogenetic protein25. Three genes were related to vitellogenin, which provides nutrition to the ovary31 and thus is indispensable for embryonic development41.…”

Mating alters the rate of development of ovarioles in the ladybird, Propylea dissecta (Coleoptera: Coccinellidae)

“…Egg maturation with age has been attributed to juvenile hormones (JH), sex peptides (SP) and ovulin (Chen et al, 1988;Herndon & Wolfner, 1995;Heifetz et al, 2000Heifetz et al, , 2005Chapman et al, 2003;Liu & Kubli, 2003). Juvenile hormones are involved in the synthesis and uptake of vitellogenin in adult female insects (Davey et al, 1993;Glinka & Wyatt, 1996;Tufail et al, 2014), and their levels vary according to the oviposition cycle (Wyatt & Davey, 1996;Borst et al, 2000). Juvenile hormone levels in many insect species are directly correlated with ovarian mass and stage of ovarian development (Koeppe et al, 1985;Okuda & Chinzei, 1988).…”

Interclonal proteomic responses to predator exposure in Daphnia magna may depend on predator composition of habitats

“…In contrast, JH or JH agonists are able to positively control vtg synthesis in adult female insects (Tufail et al . ) and crustaceans (Subramoniam ). In our study on adult female D. magna , vtg as well as a JH regulated vtg receptor (Chen & Lewis ) and a JH‐binding hormone are more abundant in animals exposed to the predator; therefore, a positive control of vtg by JH seems also likely.…”