Belden Lisa K, Wingfield John C, Kiesecker Joseph M
Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA.
J Exp Zool A Ecol Genet Physiol. 2010 Oct 1;313(8):524-31. doi: 10.1002/jez.623.
In a series of studies, we examined how larval corticosterone treatment for several species of amphibians can impact fitness parameters both during exposure and after metamorphosis. We completed confinement stress series on larvae of three species in natural/semi-natural conditions: wood frogs (Rana sylvatica), Jefferson salamanders (Ambystoma jeffersonianum), and Eastern spadefoot toads (Scaphiopus holbrooki). Two of the species had a typical vertebrate response of increasing corticosterone with confinement. However, Eastern spadefoot toads, which have a very short developmental period before metamorphosis, did not show any increase in corticosterone in response to confinement. In a second study, we treated the three species with a low and a high concentration of corticosterone (0.001 and 0.01 µM dissolved in tank water) in the laboratory and examined effects on growth. Although we were successful in raising baseline corticosterone levels with our high corticosterone concentrations, this did not translate into changes in mean larval growth for any of the three species. The larval treatments also did not appear to translate into differences in the juvenile response to confinement stress after metamorphosis. Although juvenile wood frogs did respond to confinement with increasing corticosterone, there was no variation based on larval treatment. As with the larval responses, the juvenile Eastern spadefoot toads did not have a hormonal response to confinement. In summary, while our larval corticosterone exposures did elevate baseline corticosterone levels, we did not see effects of exposure on growth or any latent effects of larval exposure on juvenile responses to confinement.
在一系列研究中，我们考察了对几种两栖动物的幼体进行皮质酮处理如何在暴露期间及变态后影响适合度参数。我们在自然/半自然条件下对三种物种的幼体完成了禁闭应激系列实验：林蛙（Rana sylvatica）、杰斐逊蝾螈（Ambystoma jeffersonianum）和东部铲足蟾（Scaphiopus holbrooki）。其中两个物种具有典型的脊椎动物反应，即随着禁闭皮质酮水平升高。然而，东部铲足蟾在变态前发育周期非常短，其皮质酮水平并未因禁闭而升高。在第二项研究中，我们在实验室用低浓度和高浓度的皮质酮（分别为溶解于养殖水中的0.001和0.01 μM）处理这三个物种，并考察对生长的影响。尽管我们成功地用高浓度皮质酮提高了基线皮质酮水平，但这并未转化为这三个物种中任何一个物种幼体平均生长的变化。幼体处理似乎也未转化为变态后幼体对禁闭应激反应的差异。尽管幼体林蛙确实会因禁闭而使皮质酮水平升高，但不存在基于幼体处理的差异。与幼体反应一样，幼体东部铲足蟾对禁闭没有激素反应。总之，虽然我们对幼体进行皮质酮暴露确实提高了基线皮质酮水平，但我们未观察到暴露对生长的影响，也未观察到幼体暴露对幼体禁闭反应的任何潜在影响。
