Respiration of Aquatic and Terrestrial Amphibian Embryos
Respiration of Aquatic and Terrestrial Amphibian Embryos
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水生和陆生两栖动物胚胎的呼吸
DOI：
--
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
R. Seymour
中科院分区：
文献类型：
--
作者：
R. Seymour
单卵和卵团结构的呼吸限制影响了两栖动物在水中和空气中的繁殖模式。水生卵通常需要较少的氧气，发育更快，更早孵化，但这些特征与卵的小尺寸有关。对两种具有相同大小卵子的水生和陆地繁殖青蛙进行比较，发现在孵化期、最大吸氧率、卵囊的氧传导或卵囊间的P o2差异没有差异。然而，水生物种的发育速度约为2.4倍，并且耐受较低的环境P o2，表明适应了短暂水的发育。对单个水生卵的扩散氧运输建模表明，如果胶囊的内半径很大，那么胶囊周围的大量果冻（或边界层）可能不会极大地限制气体交换。然而，含有其他胚胎竞争氧气的凝胶状卵团因此在大小上是有限的，除非卵之间通过水的对流通风。水生卵经常成群地悬浮在基质上方，促进氧气从各个方向进入到团体中。陆地上的卵团更受扩散限制，因为重力和表面张力使它们坍塌，阻止了卵之间的对流，并限制了氧气扩散的来源。陆生胚胎通常比水生胚胎大，对氧气的需求也更高。陆地环境选择了减少胚胎之间呼吸竞争的适应，例如，通过大量的果冻分离胚胎或减少一窝卵的数量。泡沫巢的大小是无限的，因为每个胚胎的氧气都直接来自泡沫。
Respiratory constraints on the structure of single eggs and egg masses have affected the mode of amphibian reproduction in water and in air. Aquatic eggs generally require less oxygen, develop faster, and hatch earlier, but these characteristics are related to small ovum size. A comparison of two species of aquatic and terrestrial breeding frogs with similarly sized ova shows no differences in hatching stage, maximum rate of oxygen uptake, oxygen conductance of the egg capsule, or P o2 difference across the capsule. However, the aquatic species develops about 2.4 times faster and tolerates lower environmental P o2, suggesting adaptation for development in ephemeral water. Modelling of diffusive oxygen transport into a single aquatic egg shows that a large amount of jelly (or a boundary layer) around the capsule may not greatly restrict gas exchange, if the inner radius of the capsule is large. However, gelatinous egg masses that contain other embryos that compete for oxygen are therefore limited in size, unless the eggs are ventilated by convection of water among them. Aquatic egg are often suspended in masses above the substrate, promoting oxygen movement into the mass from all directions. Terrestrial egg masses are more diffusion limited, because gravity and surface tension collapse them, preventing convection between the eggs, and restricting the source for oxygen diffusion. Terrestrial embryos are often larger than their aquatic counterparts and have higher demands for oxygen. Terrestrial conditions have selected for adaptations that reduce respiratory competition between embryos, for example, separating of embryos by large volumes of jelly or reducing the number of eggs in a clutch. The size of foam nests is unlimited, because oxygen for each embryo is supplied directly from the foam.
两栖动物胚胎的孵化：生理触发因素。
DOI：
10.1126/science.7089563
发表时间：
1982
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Petranka,JW;Just,JJ;Crawford,EC
通讯作者：
Crawford,EC