Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada, T2N 1N4.
J Exp Biol. 2010 Jun 15;213(Pt 12):2086-93. doi: 10.1242/jeb.038091.
Encapsulated freshwater pond snail embryos display a cilia-driven rotation behaviour that is stimulated by artificially induced hypoxia. Previous studies have suggested that the mixing effect of this behaviour causes enhanced oxygen delivery to embryos within their egg capsules. Despite extensive laboratory-based studies describing this behaviour, it is unclear how this behaviour is used to cope with changes in oxygen concentration and other environmental factors in natural water bodies. We made field measurements of embryo rotation rates in laboratory-reared Helisoma trivolvis embryos placed in ponds of different trophic levels that ranged geographically from the southern Alberta prairie to the Rocky Mountains. Abiotic factors including temperature, pH, conductivity and water oxygen concentration were measured to understand how embryonic rotation is influenced by environmental conditions. Results showed that H. trivolvis embryos exhibit differences in rotational behaviour depending on the environmental conditions. Temperature and oxygen concentration were the primary factors significantly affecting rotation rates. The effect of oxygen concentration on rotation rates was not as widespread as observed under laboratory conditions, probably because the measured oxygen concentrations were above the range that influences embryonic rotation in the laboratory. The rotational behaviour of laboratory-reared Lymnaea stagnalis provided confirmation that embryos of other encapsulated pulmonates exhibit a similar rotational response in natural environments. These results suggest that embryo rotation is influenced by a complex interplay of environmental factors.
包被淡水池塘蜗牛胚胎表现出纤毛驱动的旋转行为，这种行为受到人为诱导的缺氧刺激。先前的研究表明，这种行为的混合效应导致卵壳内胚胎的氧气输送增强。尽管有大量基于实验室的研究描述了这种行为，但目前尚不清楚这种行为如何用于应对自然水体中氧浓度和其他环境因素的变化。我们对在不同营养水平的池塘中培养的 Helisoma trivolvis 胚胎的胚胎旋转率进行了现场测量，这些池塘在地理上从阿尔伯塔草原南部到落基山脉。测量了包括温度、pH 值、电导率和水氧浓度在内的非生物因素，以了解胚胎旋转如何受到环境条件的影响。结果表明，H. trivolvis 胚胎的旋转行为因环境条件而异。温度和氧气浓度是显著影响旋转速度的主要因素。氧气浓度对旋转速度的影响不如实验室条件下观察到的那么广泛，可能是因为测量的氧气浓度高于实验室中影响胚胎旋转的范围。在实验室中培养的 Lymnaea stagnalis 的旋转行为证实了其他包被的陆生蜗牛胚胎在自然环境中表现出类似的旋转反应。这些结果表明，胚胎旋转受环境因素的复杂相互作用影响。
