Effect of juvenile hormone on vitellogenin gene expression in the fat body of burying beetles, Nicrophorus orbicollis

✍ Scribed by S. Carmen Panaitof; Michelle Pellissier Scott

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 951 KB
• Volume: 63
• Category: Article
• ISSN: 0739-4462
• DOI: 10.1002/arch.20144

✦ Synopsis

Abstract

In the burying beetles, Nicrophorus orbicollis, it is not clear the extent to which synthesis of Vitellogenin (Vg) is under hormonal control. Juvenile hormone (JH) and ovarian development increase rapidly upon discovery of a carcass, the necessary reproductive resource, but in its absence, treatment with JH does not accelerate ovarian development. Here we investigated the effect of manipulating JH titers on Vg gene expression in the fat bodies of newly eclosed and sexually mature females. Topical applications of the JH analogue methoprene at doses of 200, 300, and 400 μg of methoprene/g beetle to newly eclosed females resulted in up to a 5‐fold increase in fat body Vg mRNA levels compared to acetone‐treated control females. However, none of these increases were statistically significant. We also measured hemolymph Vg in females subjected to prolonged treatment with an intermediate dose of 300 μg of methoprene/g beetle and found no statistically significant increase in hemolymph Vg following treatment. There was, however, a significantly positive correlation between Vg mRNA and hemolymph Vg. Conversely, although injecting sexually mature females with fluvastatin (an inhibitor of JH biosynthesis in the corpora allata) at a dose of 40 μg/ beetle resulted in significantly decreased JH titers in treated females compared to saline‐injected controls, Vg transcription rates were not affected. We suggest that in burying beetles, JH alone is not sufficient to upregulate the expression of the Vg genes and that other factors may be involved in regulating their vitellogenic cycle as well. Arch. Insect Biochem. Physiol. 63:82–91, 2006. © 2006 Wiley‐Liss, Inc.