Selechnik Daniel, West Andrea J, Brown Gregory P, Fanson Kerry V, Addison BriAnne, Rollins Lee A, Shine Richard
School of Life and Environmental Sciences (SOLES), University of Sydney, Sydney, NSW, Australia.
Centre for Integrative Ecology, School of Life & Environmental Sciences (LES), Deakin University, Geelong, VIC, Australia.
PeerJ. 2017 Oct 6;5:e3856. doi: 10.7717/peerj.3856. eCollection 2017.
The cane toad () has undergone rapid evolution during its invasion of tropical Australia. Toads from invasion front populations (in Western Australia) have been reported to exhibit a stronger baseline phagocytic immune response than do conspecifics from range core populations (in Queensland). To explore this difference, we injected wild-caught toads from both areas with the experimental antigen lipopolysaccharide (LPS, to mimic bacterial infection) and measured whole-blood phagocytosis. Because the hypothalamic-pituitary-adrenal axis is stimulated by infection (and may influence immune responses), we measured glucocorticoid response through urinary corticosterone levels. Relative to injection of a control (phosphate-buffered saline), LPS injection increased both phagocytosis and the proportion of neutrophils in the blood. However, responses were similar in toads from both populations. This null result may reflect the ubiquity of bacterial risks across the toad's invaded range; utilization of this immune pathway may not have altered during the process of invasion. LPS injection also induced a reduction in urinary corticosterone levels, perhaps as a result of chronic stress.
甘蔗蟾蜍（）在入侵澳大利亚热带地区的过程中经历了快速进化。据报道，来自入侵前沿种群（西澳大利亚）的蟾蜍比来自分布核心种群（昆士兰）的同种蟾蜍表现出更强的基础吞噬免疫反应。为了探究这种差异，我们给来自这两个地区的野生捕获蟾蜍注射了实验性抗原脂多糖（LPS，以模拟细菌感染），并测量了全血吞噬作用。由于下丘脑 - 垂体 - 肾上腺轴会受到感染刺激（且可能影响免疫反应），我们通过尿液皮质酮水平测量了糖皮质激素反应。相对于注射对照物（磷酸盐缓冲盐水），注射LPS增加了吞噬作用以及血液中中性粒细胞的比例。然而，两个种群的蟾蜍的反应相似。这个无效结果可能反映了细菌风险在蟾蜍整个入侵范围内的普遍存在；在入侵过程中，这种免疫途径的利用可能没有改变。注射LPS还导致尿液皮质酮水平降低，这可能是慢性应激的结果。
