Evolutionary relationship of fat body endoreduplication and queen fecundity in termites

Endoreduplication or nuclear genome replication without cell division is widely observed in the metabolically active tissues of plants and animals. The fat body cells of adult female insects produce abundant yolk proteins and become polyploid, which is assumed to accelerate egg production. Recently, it was reported that in termites, endopolyploidy in the fat body occurs only in queens but not in the other females; however, the relationship between the fecundity and ploidy level in the fat body remains unclear. Termite queens exhibit a huge variation in their egg producing capacity among different species; queens in the species with a foraging lifestyle, in which workers leave the nest to forage outside, are much more fecund than those in the species living in a single piece of wood. In this study, we conducted ploidy analyses on three foraging and three wood-dwelling termites via flow cytometry. In all the species, the fat body of queens contained significantly more polyploid cells than...核内复制（endoreduplication，即不伴随细胞分裂的核基因组复制）广泛存在于动植物的代谢活跃组织中。成年雌性昆虫的脂肪体细胞（fat body）可合成大量卵黄蛋白并形成多倍体，该过程被认为能够促进卵子生成。近期研究显示，白蚁脂肪体的内多倍性仅存在于蚁后体内，而非其他雌性个体；但脂肪体倍性水平与繁殖力之间的关联仍尚不明确。不同白蚁物种的蚁后产卵能力差异悬殊：具有觅食型生活史（即工蚁离巢外出觅食）的物种，其蚁后繁殖力远高于仅栖息于单块木材中的物种。本研究通过流式细胞术（flow cytometry）对3种觅食型白蚁和3种木栖性白蚁开展了倍性分析。在所有受试物种中，蚁后的脂肪体所含多倍体细胞数量均显著多于……