Golding D W, Yuwono E
Department of Marine Sciences and Coastal Management, University of Newcastle upon Tyne, United Kingdom.
Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):11777-81. doi: 10.1073/pnas.91.25.11777.
Most nereid polychaetes are strictly semelparous, a single episode of reproduction being invariably followed by death. Endocrine manipulation in Nereis diversicolor by the regular implantation of cerebral ganglia from immature donors unveils characteristics associated with a capacity to engage in repeated gametogenic cycling. Such manipulation permits full maturation of the gametes but blocks spawning. Gamete resorption then leads on to another bout of gametogenesis and a new cohort of gametes is formed. The neurosecretory system adopts a cyclical pattern of activity, which parallels that of gametogenesis. Repair and maintenance of the soma continue throughout sexual maturation, as shown by the persistence of feeding and the capacity for regenerative segment proliferation. In consequence, life is extended apparently indefinitely. These latent capacities are reminiscent of features of iteroparous life histories, characterized by repeated breeding, and are postulated to be vestiges of an iteroparous ancestry. They also constitute a preadaptation for iteroparity and reveal how readily a reversal to this condition could occur. The study suggests that reproductive strategies may be unexpectedly labile in even their most fundamental aspects.
大多数沙蚕多毛纲动物严格单次生殖，一次繁殖后必然死亡。通过定期植入未成熟供体的脑神经节对变色沙蚕进行内分泌调控，揭示了与重复配子发生循环能力相关的特征。这种调控使配子完全成熟，但阻止产卵。然后配子吸收引发另一轮配子发生，形成新的配子群体。神经分泌系统呈现出周期性的活动模式，这与配子发生的模式相似。如进食的持续和再生节段增殖的能力所示，在性成熟过程中，体细胞的修复和维持一直在进行。因此，寿命显然会无限延长。这些潜在能力让人联想到多次生殖生活史的特征，即以重复繁殖为特点，并被假定为多次生殖祖先的遗迹。它们也构成了对多次生殖的预适应，并揭示了向这种状态逆转是多么容易发生。该研究表明，即使在最基本的方面，生殖策略也可能出人意料地不稳定。
