Hatle John D, Juliano Steven A, Borst David W
Department of Biological Sciences, Illinois State University, Normal, Illinois 61790-4120, USA.
Arch Insect Biochem Physiol. 2003 Jan;52(1):45-57. doi: 10.1002/arch.10067.
The role of hemolymph ecdysteroids in the reproduction of non-dipteran insects is unclear. We examine the role(s) of hemolymph ecdysteroids during egg production in the lubber grasshopper, Romalea microptera. In all individuals, hemolymph ecdysteroids rose to a sharp peak with similar maxima and then fell to undetectable levels. The time from the adult molt to the maximum ecdysteroid titer (E(max) titer) varied in response to food availability, whereas the time from E(max) titer to oviposition was unrelated to food availability. Because both the timing of egg production and the timing of E(max) responded similarly to environmental changes, ecdysteroids may be involved in egg production. We hypothesized that this role is the stimulation of vitellogenesis. Ovariectomized females had vitellogenin but no ecdysteroids, so ecdysteroids are not necessary for vitellogenin production. In addition, treatment of females with ecdysteroids altered neither Vg titers nor ovarian growth. Ovarian ecdysteriods increased at the same age in development as hemolymph ecdysteroids. In contrast to hemolymph ecdysteroids, ovarian ecdysteroids persisted until oviposition. Despite this, [(3)H]ecdysone injected into the hemolymph was detected later only at very low levels in the ovary, suggesting that hemolymph ecdysteroids are not sequestered by the ovary. In summary, our studies indicate that hemolymph ecdysteroids in adult females of the lubber grasshopper are associated with the timing of egg production, but they neither regulate vitellogenesis nor act as a source of ecdysteroids for the ovary.
血淋巴蜕皮类固醇在非双翅目昆虫繁殖中的作用尚不清楚。我们研究了血淋巴蜕皮类固醇在美洲沙漠蝗（Romalea microptera）产卵过程中的作用。在所有个体中，血淋巴蜕皮类固醇都急剧上升至相似的最大值，然后降至检测不到的水平。从成虫蜕皮到蜕皮类固醇滴度最大值（E(max)滴度）的时间因食物供应情况而有所不同，而从E(max)滴度到产卵的时间与食物供应情况无关。由于产卵时间和E(max)时间对环境变化的反应相似，蜕皮类固醇可能参与了产卵过程。我们假设其作用是刺激卵黄发生。切除卵巢的雌性有卵黄原蛋白但没有蜕皮类固醇，所以蜕皮类固醇对于卵黄原蛋白的产生不是必需的。此外，用蜕皮类固醇处理雌性既不改变卵黄原蛋白滴度也不改变卵巢生长。卵巢蜕皮类固醇在发育中的相同年龄与血淋巴蜕皮类固醇同时增加。与血淋巴蜕皮类固醇不同，卵巢蜕皮类固醇一直持续到产卵。尽管如此，注入血淋巴的[(3)H]蜕皮激素后来仅在卵巢中以非常低的水平被检测到，这表明血淋巴蜕皮类固醇不会被卵巢所隔离。总之，我们的研究表明，美洲沙漠蝗成年雌性的血淋巴蜕皮类固醇与产卵时间有关，但它们既不调节卵黄发生，也不作为卵巢蜕皮类固醇的来源。
