Cadierno M P, Saveanu L, Dreon M S, Martín P R, Heras H
Biol Bull. 2018 Aug;235(1):1-11. doi: 10.1086/699200. Epub 2018 Aug 10.
High fecundity often contributes to successful invasives. In molluscs, this may be facilitated by the albumen gland-capsule gland complex, which in gastropods secretes the egg perivitelline fluid that nourishes and protects embryos. The biochemistry of the albumen gland-capsule gland complex and its relationship with fecundity remain largely unknown. We addressed these issues in Pomacea canaliculata (Lamarck, 1822), a highly invasive gastropod whose fecundity and reproductive effort exceed those of ecologically similar gastropods. We evaluated the dynamics of its major secretion compounds (calcium, polysaccharides, and total proteins) as well as the gene expression and stored levels of perivitellins during key moments of the reproductive cycle, that is, before and after first copulation and at low, medium, and high reproductive output. Copulation and first oviposition do not trigger the onset of albumen gland-capsule gland complex biosynthesis. On the contrary, soon after an intermediate reproductive effort, genes encoding perivitellins overexpressed. A high reproductive effort caused a decrease in all albumen gland-capsule gland complex secretion components. Right after a high reproductive output, the albumen gland-capsule gland complex restored the main secretion components, and calcium recovered baseline reserves; but proteins and polysaccharides did not. These metabolic changes in the albumen gland-capsule gland complex after multiple ovipositions were reflected in a reduction in egg mass but did not compromise egg quality. At the end of the cycle, egg dry weight almost doubled the initial albumen gland-capsule gland complex weight. Results indicate that albumen gland-capsule gland complex biosynthesis limits a constantly high reproductive output. Therefore, lowering fecundity by targeting biosynthesis could effectively reduce the rate of this species' spread.
高繁殖力往往有助于物种成功入侵。在软体动物中，这可能由蛋白腺 - 壳腺复合体促成，在腹足纲动物中，该复合体分泌卵周液，为胚胎提供营养并保护它们。蛋白腺 - 壳腺复合体的生物化学及其与繁殖力的关系在很大程度上仍不为人知。我们在福寿螺（Pomacea canaliculata，拉马克，1822年）中研究了这些问题，福寿螺是一种极具入侵性的腹足纲动物，其繁殖力和繁殖投入超过了生态习性相似的腹足纲动物。我们评估了其主要分泌化合物（钙、多糖和总蛋白）的动态变化，以及在生殖周期的关键阶段，即首次交配前后以及低、中、高繁殖产出时，卵黄蛋白原的基因表达和储存水平。交配和首次产卵不会触发蛋白腺 - 壳腺复合体生物合成的开始。相反，在中等繁殖投入后不久，编码卵黄蛋白原的基因就会过度表达。高繁殖投入导致蛋白腺 - 壳腺复合体所有分泌成分减少。在高繁殖产出后，蛋白腺 - 壳腺复合体恢复了主要分泌成分，钙恢复到基线储备水平；但蛋白质和多糖没有恢复。多次产卵后蛋白腺 - 壳腺复合体的这些代谢变化反映在卵块质量的降低上，但并未损害卵的质量。在周期结束时，卵的干重几乎是初始蛋白腺 - 壳腺复合体重量的两倍。结果表明，蛋白腺 - 壳腺复合体生物合成限制了持续的高繁殖产出。因此，通过靶向生物合成来降低繁殖力可以有效降低该物种的扩散速度。
