Abstract：
AbstractThe common eastern bumble bee (Bombus impatiens) queens endure cold winter months by entering a diapause state. During this overwintering period, these animals use stored energy reserves while maintaining a low metabolic rate. This study investigates changes in the metabolic rate of bumble bee queens during diapause-like laboratory conditions and the potential reorganization of the flight muscle metabolic properties during this period. We first confirmed the hypometabolic state of queens during diapause in the laboratory, which lowered their resting metabolic rate to less than 5% of normal resting values. Body mass decreased during diapause, body composition changed where carbohydrates decreased initially, and later protein declined, with a similar trend for lipid content. Using cellular respirometry, we determined the capacity of the flight muscle cells of bumble bee queens to use various metabolic fuels and whether this capacity changes during the progression of diapause to favor stored lipid-derived substrates. Queens showed a low capacity to oxidize the amino acid proline, compared with workers, and their capacity to oxidize all metabolic substrates did not change during a 4-mo diapause period in the laboratory. We also show no detectable ability to oxidize fatty acid by flight muscle mitochondria in this species. The metabolic properties of flight muscle tissue were further characterized using metabolic enzyme activity profiles showing little change during diapause, indicating that profound metabolic suppression is induced without major changes in muscle metabolic phenotypes. Overall, B. impatiens queens undergo diapause while maintaining flight muscle capacity under the conditions used.
摘要：
普通的东部大黄蜂（Bombusimpatiens）皇后通过进入滞育状态而忍受寒冷的冬季。在这个越冬时期，这些动物利用储存的能量储备，同时保持低代谢率。这项研究调查了类似滞育的实验室条件下大黄蜂皇后的代谢率变化以及在此期间飞行肌肉代谢特性的潜在重组。我们首先在实验室中证实了皇后区在滞育期间的低代谢状态，这将他们的静息代谢率降低到正常静息值的5%以下。滞育期间体重下降，身体成分改变了碳水化合物最初减少的地方，后来蛋白质下降了，脂质含量的趋势相似。使用细胞呼吸测量法，我们确定了大黄蜂皇后的飞行肌肉细胞使用各种代谢燃料的能力，以及这种能力在滞育过程中是否会发生变化，以有利于储存的脂质来源的底物。皇后区对氨基酸脯氨酸的氧化能力很低，与工人相比，在实验室的4个月滞育期间，它们氧化所有代谢底物的能力没有变化。我们还显示出在该物种中没有可检测到的通过飞行肌肉线粒体氧化脂肪酸的能力。使用代谢酶活性谱进一步表征飞行肌肉组织的代谢特性，显示滞育期间几乎没有变化，这表明在肌肉代谢表型没有重大变化的情况下诱导了深度代谢抑制。总的来说,在所使用的条件下，凤仙花皇后在保持飞行肌肉能力的同时进行滞育。
