Characterization of a Vitellogenin Receptor in the Bumblebee, Bombus lantschouensis (Hymenoptera, Apidae)

Abstract

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) family, responsible for mediating the endocytosis of vitellogenin (Vg) into the ovaries to promote ovarian growth and oviposition. Here, we cloned and measured VgR gene expression characteristics in the bumblebee Bombus lantschouensis. RNA interference was used to validate VgR function. The results showed that the full length of the BLVgR cDNA was 5519 bp, which included a 5280 bp open reading frame encoding 1759 amino acids (AAs). Sequence alignment revealed that the protein contained 12 LDLa, 5 EGF, 2 EGF-CA and 10 LY domains. Phylogenetic analysis showed that BLVgR and the VgR of Bombus terrestris clustered together and the tree of bumblebees (Bombus) appeared as one clade next to honeybees (Apis). Transcript expression analysis showed that BLVgR was expressed in all tested tissues and showed the highest abundance in the ovaries. BLVgR expression was present in all developmental stages. However, the expression level in larvae was extremely low. In addition, the expression of BLVgR was significantly upregulated after egg laying in both workers and queens. In new emerging workers injected with 5 µg of VgR dsRNA, the expression level of BLVgR was 4-fold lower than that in the GFP dsRNA-injected group after 72 h. Furthermore, BLVgR silencing significantly reduced the number of eggs laid (3.67 ± 1.96 eggs) and delayed the first egg-laying time (16.31 ± 2.07 days) in worker microcolonies when compared to dsGFP (37.31 ± 4.09 eggs, 8.15 ± 0.22 days) and DEPC-treated water injected controls (16.42 ± 2.24 eggs, 10.00 ± 0.37 days). In conclusion, the BLVgR gene and its reproductive function were explored in the bumblebee B. lantschouensis. This gene plays an important role in egg laying time and egg number.

Molecular evolution of bumble bee vitellogenin and vitellogenin‐like genes

“…To date, for most multi-species Vg analysis, bumble bee Vg sequences were compared with species from other genera (Du et al, 2019;Li et al, 2010;Salmela et al, 2016), probably due to the lack of sequence data from multiple bumble bee species. In this study, based on 27 bumble bee genomes, and combined with genomes of their phylogenetically close relatives (honey bees and stingless bees), we conducted the first large-scale molecular evolutionary analyses of bumble bee Vg and Vg-like genes to understand the selective patterns of Vg gene family in bumble bees.…”

Research Progress on Oviposition-Related Genes in Insects

“…The oviposition-related genes of insects are mainly divided into four categories: the genes controlling oviposition-related glands, the egg surface, oviposition-site-selection-related, and ovulation and egg hatching; these genes may directly or indirectly affect the oviposition of insects ( Du et al 2019 , Guo et al 2019 , Ma et al 2019 , Peng et al 2020 ). To date, RNA interference (RNAi) and CRISPR/CRISPR-associated protein 9 (CRISPR/Cas9) have been used to study some oviposition-related genes in detail; the combination of RNAi and other methods to control plant diseases and injurious pests is especially important, and a small amount of commercial application has begun ( Killiny and Kishk 2017 , Yu et al 2017 , Dao and Illiny 2018 , Yu and Killiny 2018a , Abdullaha et al 2019 , Avelar et al 2019 , Chen et al 2019a , Fandino et al 2019 , Hao et al 2019 , Liu et al 2019a , Lin et al 2019 , Lu et al 2019a , Ortega and Killiny 2019 , Richard et al 2019 , Wang et al 2019a , Dias et al 2020 ).…”

The RNA helicase DDX3 is required for ovarian development and oocyte maturation in Locusta migratoria

“…VgR belongs to low‐density lipoprotein receptor superfamily (Raikhel & Dhadialla, 1992; Sappington & Raikhel, 1998), and plays indispensible role in vitellogenesis (Cong et al, 2015; Shang et al, 2018). Knockdown VgR by RNAi or knockout VgR by Crispr/cas9 in many insects produces similar phenotypes such as reduced Vgs in ovary, accumulation of Vgs in hemolymph and reduced fecundity (Du et al, 2019; Hu et al, 2019; Husain et al, 2020; Liu et al, 2019; Lu et al, 2015; Miao et al, 2020; Mitchell et al, 2007; Peng et al, 2019; Shang et al, 2018; Shu et al, 2016; Thomas et al, 2020; Tufail & Takeda, 2005; Xiang et al, 2019), suggesting a conserved role for VgR in insects. One VgR exists in locust and is expressed primarily in ovary (Ferenz, 1993).…”