An urn model of the development of L/M cone ratios in human and macaque retinas.
An urn model of the development of L/M cone ratios in human and macaque retinas.
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人类和猕猴视网膜 L/M 视锥细胞比率发育的瓮模型。
DOI：
10.1017/s0952523806233157
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Neitz,Jay
中科院分区：
文献类型：
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作者：
Knoblauch,Kenneth;Neitz,Maureen;Neitz,Jay
提出了一种东半球灵长类动物视网膜视锥比的发展模型。据推测，在妊娠期间，视锥细胞在转录L或M视蛋白的状态之间随机循环。当前的状态决定并增加了它在未来周期中转录相同视蛋白的可能性。这些假设足以将这一过程形式化为一个马尔可夫链，该链可以建模为一个包含两种球（L和m）的瓮。绘制一个球导致其种类增加而另一个减少。长此以往，骨灰盒里的球只会变成一种类型。这种状态对应于光感受器在其一生中采用固定的身份。我们研究了状态数和向一种或另一种锥体类型转换优势的调节规则对胎儿和成人L/M锥体比率关系的影响。在100到1000个状态范围内，初始L/M比或过渡优势的微小变化都能产生最终L/M比的巨大变化，与人类成人视网膜的变化在质上一致。达到稳定的L/M比率的时间过程也随这些参数而变化。如果相信这种循环遵循昼夜节律，那么人类和猕猴的最终L/M锥体比率将在出生后不久稳定下来。
A model of the development of L/M cone ratios in the Old World primate retina is presented. It is supposed that during gestation, the cone cycles randomly between states in which it transcribes either L or M opsin. The current state determines and increases the probability that it will transcribe the same opsin in future cycles. These assumptions are sufficient to formalize the process as a Markov chain that can be modeled as an urn containing two types of balls, L and M. Drawing one ball results in the increase of its species and the decrease of the other. Over the long run, the urn will become populated with a single type of ball. This state corresponds to the photoreceptor adopting a fixed identity for its lifetime. We investigate the effect of the number of states and the rule that regulates the advantage of transition toward one cone type or another on the relation between fetal and adult L/M cone ratios. In the range of 100 to 1000 states, small variations of the initial L/M ratio or the transition advantage can each generate large changes in the final L/M ratio, in qualitative accord with the variation seen in human adult retinas. The time course to attain stable L/M ratios also varies with these parameters. If it is believed that the cycling follows a circadian rhythm, then final L/M cone ratios would be expected to stabilize shortly after birth in the human being and the macaque.