Scott Michelle Pellissier, Panaitof S Carmen, Carleton Karen L
Department of Zoology and Hubbard Center for Genome Studies, University of New Hampshire, 46 College Rd, Durham, NH 03824, USA.
J Insect Physiol. 2005 Mar;51(3):323-31. doi: 10.1016/j.jinsphys.2004.12.014.
Burying beetles (Nicrophorus orbicollis) are unusual in that to breed they require an unpredictable and valuable resource, a small carcass. Thus the timing of reproduction is unpredictable and beetles' physiological response must be fast. We hypothesized that their pattern of vitellogenin (Vg) synthesis might reflect these requirements. We examined the expression of two Vg genes (sequenced for this study) during sexual maturation and through a reproductive bout. Vg-mRNA, juvenile hormone (JH) titers, ovarian development, and hemolymph concentrations of Vg were quantified in the same individuals. All four variables gradually increased during maturation to peak 15-20 days after eclosion. Twelve hours after the discovery of a carcass, a few hours before oviposition, mRNA was high, hemolymph Vg had decreased, JH and ovarian weight had increased. After oviposition, mRNA was low, hemolymph Vg concentrations and JH were high. This is consistent with our hypothesis that beetles produce and store Vg in the hemolymph prior to the discovery of a breeding resource and replace it quickly. Partial regression of these variables (with the effect of time removed) indicated that JH was not correlated with mRNA, hemolymph Vg, or ovarian weight at any time. Thus the role of JH as a gonadotropin remains unclear.
埋葬虫（Nicrophorus orbicollis）不同寻常之处在于，它们繁殖需要一种不可预测且珍贵的资源——一具小型动物尸体。因此，繁殖时间无法预测，而甲虫的生理反应必须迅速。我们推测它们的卵黄原蛋白（Vg）合成模式可能反映了这些需求。我们研究了两个Vg基因（为本研究测序）在性成熟期间以及整个繁殖周期中的表达情况。对同一批个体的Vg - mRNA、保幼激素（JH）滴度、卵巢发育情况以及血淋巴中Vg的浓度进行了量化。在成熟过程中，所有这四个变量都逐渐增加，在羽化后15 - 20天达到峰值。发现尸体12小时后，即产卵前几小时，mRNA水平较高，血淋巴Vg含量下降，JH和卵巢重量增加。产卵后，mRNA水平较低，血淋巴Vg浓度和JH较高。这与我们的假设一致，即甲虫在发现繁殖资源之前就在血淋巴中产生并储存Vg，然后迅速补充。对这些变量进行偏回归分析（去除时间影响）表明，JH在任何时候都与mRNA、血淋巴Vg或卵巢重量无关。因此，JH作为促性腺激素的作用仍不清楚。
