Allocation of Nutrients to Somatic Tissues in Young Ovariectomized Grasshoppers
Allocation of Nutrients to Somatic Tissues in Young Ovariectomized Grasshoppers
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DOI：
10.1093/icb/icq105
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发表时间：
2010-11-01
影响因子：
2.6
通讯作者：
Hahn, Daniel A.
中科院分区：
文献类型：
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作者：
Judd, Evan T.;Hatle, John D.;Hahn, Daniel A.
一次性索马假说预测，当繁殖减少时，寿命会增加，因为更多的营养物质被投入到索马中，增加了躯体修复。严格检验这一假设需要跟踪营养素从摄入到分配到索马或生殖的过程。果蝇对延长寿命的饮食限制增加分配到索马“相对”的繁殖，这表明营养物质的分配可以与延长寿命。在这里，我们使用稳定的同位素来跟踪摄入的营养素在卵巢切除蝗虫在第一个产卵周期。先前的研究表明，卵巢切除术延长了寿命，但在第一窝卵产下之前，生殖过程中的蛋白质投资不会减少。因为卵巢切除术在这个年龄并不影响生殖的投资，所以一次性索马假说预测卵巢切除术也不应该影响体组织的投资。我们开发了具有不同特征的C-13和N-15的蚱蜢饮食，但产生了相等的生殖输出。因此，这些饮食适合于追踪摄入的营养素所需的饮食中的相互转换。将稳定同位素掺入卵中表明，蚱蜢是收入的繁殖者，特别是碳。卵巢切除术使成年人摄入的氮分配到脂肪体的比例略有增加，这是我们唯一与一次性索马假说不一致的结果。相比之下，卵巢切除术并不影响分配的氮股肌肉。此外，碳分配到脂肪体或股骨肌肉似乎不受卵巢切除术的影响。总的抗氧化活性的血淋巴和股骨肌肉卵巢切除术没有受到影响。这些实验表明，营养物质的分配改变不大，卵巢切除术在年轻的蝗虫。需要对老年人进行更多的研究，以进一步检验一次性索马假说。
The disposable soma hypothesis predicts that when reproduction is reduced, life span is increased because more nutrients are invested in the soma, increasing somatic repair. Rigorously testing the hypothesis requires tracking nutrients from ingestion to allocation to the soma or to reproduction. Fruit flies on life-extending dietary restriction increase allocation to the soma "relative'' to reproduction, suggesting that allocation of nutrients can be associated with extension of life span. Here, we use stable isotopes to track ingested nutrients in ovariectomized grasshoppers during the first oviposition cycle. Previous work has shown that ovariectomy extends life span, but investment of protein in reproduction is not reduced until after the first clutch of eggs is laid. Because ovariectomy does not affect investment in reproduction at this age, the disposable soma hypothesis would predict that ovariectomy should also not affect investment in somatic tissues. We developed grasshopper diets with distinct signatures of C-13 and N-15, but that produced equivalent reproductive outputs. These diets are, therefore, appropriate for the reciprocal switches in diet needed for tracking ingested nutrients. Incorporation of stable isotopes into eggs showed that grasshoppers are income breeders, especially for carbon. Allocation to the fat body of nitrogen ingested as adults was slightly increased by ovariectomy; this was our only result that was not consistent with the disposable soma hypothesis. In contrast, ovariectomy did not affect allocation of nitrogen to femoral muscles. Further, allocation of carbon to the fat body or femoral muscles did not appear to be affected by ovariectomy. Total anti-oxidant activities in the hemolymph and femoral muscles were not affected by ovariectomy. These experiments showed that allocation of nutrients was altered little by ovariectomy in young grasshoppers. Additional studies on older individuals are needed to further test the disposable soma hypothesis.