Arrese C A, Rodger J, Beazley L D, Shand J
School of Animal Biology, University of Western Australia, Crawley 6009, Australia.
Vis Neurosci. 2003 May-Jun;20(3):307-11. doi: 10.1017/s0952523803203096.
Microspectrophotometry indicates the presence of at least three cone visual pigments in two Australian marsupials, the fat-tailed dunnart (Sminthopsis crassicaudata) and honey possum (Tarsipes rostratus). Here we have examined the distribution of cone types using antisera, JH455 and JH492, that recognize short-wavelength-sensitive (SWS) and medium-to-long-wavelength-sensitive (M/LWS) cone opsins, respectively. SWS cones were concentrated in dorso-temporal retina in the dunnart with a shallow decreasing gradient extending to the periphery (2300-1500/mm2). In the honey possum, SWS cones showed a uniform distribution (2700/mm2), except for a slight increase in a narrow peripheral band (3100/mm2). In both species, M/LWS cones dominated and their distributions were similar to those of retinal ganglion cells: a horizontal streak in the dunnart (31,000-21,000/mm2) and a shallow mid-ventral to peripheral gradient in the honey possum (37,000-26,000/mm2). A low number of cones remained unlabeled when the antisera were combined revealing further minority cone population(s). We discuss cone distributions in relation to visual capabilities and requirements of the species.
显微分光光度测定法表明，在两种澳大利亚有袋动物——肥尾袋鼬（Sminthopsis crassicaudata）和蜜袋鼯（Tarsipes rostratus）中，至少存在三种视锥视觉色素。在这里，我们使用分别识别短波敏感（SWS）和中长波敏感（M/LWS）视锥视蛋白的抗血清JH455和JH492，研究了视锥类型的分布。在袋鼬中，SWS视锥集中在颞背视网膜，从这里到周边存在一个浅的递减梯度（2300 - 1500个/平方毫米）。在蜜袋鼯中，SWS视锥呈现均匀分布（2700个/平方毫米），除了在一个狭窄的周边带稍有增加（3100个/平方毫米）。在这两个物种中，M/LWS视锥占主导，其分布与视网膜神经节细胞的分布相似：在袋鼬中呈水平条纹状（31,000 - 21,000个/平方毫米），在蜜袋鼯中从中腹到周边呈浅梯度分布（37,000 - 26,000个/平方毫米）。当将抗血清结合使用时，仍有少量视锥未被标记，这揭示了更多的少数视锥群体。我们讨论了视锥分布与物种视觉能力和需求的关系。
