Sex-specific and hormone-controlled expression of a vitellogenin-encoding gene in the gypsy moth

Analyses of adult transcriptomes from four different populations of the spongy moth, Lymantria dispar L., from China and the USA

The spongy moth Lymantria dispar, formerly known as the gypsy moth, is a forest pest that occurs as two different biotypes: the European spongy moth (ESM), Lymantria dispar dispar, which is distributed in Europe and North America; and the Asian spongy moth (ASM), which consists of subspecies Lymantria dispar asiatica and Lymantria dispar japonica and is distributed in China, Russia, Korea, and Japan. The Asian biotype is classified as a quarantine pest by the U.S. Department of Agriculture because of the superior flight ability of adult females compared to females of the European biotype. To identify genes that potentially account for differences in female flight capability between the two biotypes, we assembled and compared transcriptional profiles of two North American populations of ESM and two Chinese populations of ASM, including samples of unmated female adults and females after mating and oviposition. Of 129,286 unigenes identified, 306 were up-regulated in ASM samples relative to ESM, including genes involved in egg production. In contrast, 2309 unigenes were down-regulated in ASM samples, including genes involved in energy production. Although a previous study found that ASM female flight was reduced after oviposition, a comparison of gene expression before and after mating and oviposition did not reveal any genes which were consistently up- or down-regulated in the two ASM populations.

VHDL, a larval storage protein from the corn earworm, Helicoverpa zea, is a member of the vitellogenin gene family

The hemolymph of last instar larvae of the corn earworm, Helicoverpa zea contains a blue very high-density lipoprotein (VHDL) that is selectively taken up into fat body prior to pupation. Its amino-terminal sequence was determined by Edman degradation, and used to design a degenerate primer for PCR amplification. With 5' and 3' RACE techniques, the entire cDNA coding for VHDL was amplified and sequenced. Conceptual translation reveals a 173 kDa protein that contains a 15 amino acid signal sequence immediately before the experimentally determined N-terminus of the mature protein. The protein contains a typical lipoprotein N-terminal domain, and shows high sequence similarity to vitellogenins from Lepidoptera and other insect species. VHDL mRNA was not detectable in adult H. zea, and antibodies raised against VHDL did not react with adult hemolymph or yolk proteins. Therefore VHDL, although a member of the vitellogenin gene family, seems to be distinct from the vitellogenin expressed in adult females.

Vitellogenin expression in queen ovaries and in larvae of both sexes of Apis mellifera

In the honeybee, Apis mellifera, vitellogenin (Vg) expression has been detected in the ovary of queens, but not in that of workers. In addition, larvae of both sexes produce Vg in significant amounts, which suggest that Vg serves for functions additional to oocyte growth and energy supply to the embryo. In vivo hormone treatment experiments suggest that the decrease of 20-hydroxyecdysone concentration occurring in previtellogenic phases allows Vg production. Southern analysis indicates that the Vg gene is present as a single copy in the honeybee genome.