BARRY, T.O.; MARTIN, T.R.; FEI, H.; HATLE, J.D.; BORST, D.W.; Illinois State University, Normal: The regulation of vitellogenin production in the lubber grasshopper, Romalea microptera.

Previous studies have shown that juvenile hormone (JH) stimulates vitellogenin (Vg) production in many insects. To investigate the regulation of Vg production in the lubber grasshopper, we allatectomized (CA-; removal of the source of JH) females five days after the adult molt and measured Vg-mRNA levels 13 days later. CA- animals had <1% of the Vg mRNA detected in sham operated animals, and treatment of CA- animals with JH for the final three days elevated Vg-mRNA levels 24-fold above the levels observed in CA- animals treated with saline. These results indicate that JH stimulates vitellogenin production. Other females were well fed for 17 days after the adult molt, and then moved to individual containers. Some of these animals were then well fed and the others were starved. Animals from each group were killed 48 and 96 hrs later. Some of their fat body (FB) tissue was incubated in vitro for 4 hrs and the amount of Vg produced was determined by ELISA. Vg-mRNA levels were measured in the remaining FB tissue. Starvation decreased JH levels to 32% and 23% of the levels in control animals at 48 and 96 hr, respectively. Likewise, the in vitro production of Vg in FB from starved animals dropped to 54 and 2% of the levels in control animals after 48 and 96 hrs, respectively. In contrast, levels of Vg-mRNA were not affected by starvation. The infusion of starved animals with JH for 48 hr had no effect on Vg production by the FB but did cause a 2-fold increase in Vg-mRNA levels. These data indicate that Vg production is controlled by two different mechanisms: JH stimulates the production of Vg-mRNA in the FB, and some other (as yet unidentified) factor controls its translation. (Supported by NSF grant DBI – 9978810 to DWB).