Molecular shifts in limb identity underlie development of feathered feet in two domestic avian species.
Molecular shifts in limb identity underlie development of feathered feet in two domestic avian species.
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肢体身份的分子转移是两个家用禽类中羽毛脚发育的基础。
DOI：
10.7554/elife.12115
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发表时间：
2016-03-15
期刊：
影响因子：
7.7
通讯作者：
Shapiro MD
中科院分区：
文献类型：
--
作者：
Domyan ET;Kronenberg Z;Infante CR;Vickrey AI;Stringham SA;Bruders R;Guernsey MW;Park S;Payne J;Beckstead RB;Kardon G;Menke DB;Yandell M;Shapiro MD
鸟类在鳞片和脚羽的分布和形态上表现出显著的多样性，但这种多样性的遗传和发育机制仍不清楚。家鸽在同一物种中足羽的变化非常显著，这为研究皮肤附属器差异的分子基础提供了一个易处理的模型。我们发现，羽脚在鸽子的结果从后肢到前肢的身份介导的顺式调节变化的基因编码的后肢特异性转录因子Pitx 1和前肢特异性转录因子Tbx 5的部分转化。我们还发现Tbx 5的异位表达与鸡的脚羽有关，这表明这两个物种之间表型趋同的分子途径相似。这些结果表明，如何在区域图案化基因的表达变化可以产生本地化的器官命运和形态的变化，并提供可行的分子机制的多样性后肢规模和羽毛分布。http://dx.doi.org/10.7554/eLife.12115.001从鱼类到鸟类的动物在物种内部和物种之间表现出巨大的多样性;然而，人们对这种变异背后的遗传和发育机制知之甚少。在鸟类及其灭绝的恐龙亲属中，脚上鳞片和羽毛的分布是一个高度可变的特征。不同品种的家鸽都属于同一物种，但脚上有羽毛或鳞片的程度不同。经典的遗传学实验表明，只有少数基因参与了鸽子脚上皮肤从鳞片到羽毛的转变。然而，这种转变的分子基础是未知的。Domyan等人通过在实验室中让不同品种的鸽子交配，然后对鸽子的DNA进行测序，着手确定从鳞片脚到羽毛脚转变所涉及的基因。他们还调查了许多其他鸽子品种的整个DNA序列，这些鸽子有羽毛脚和没有羽毛脚。这种结合的方法表明，鸽子基因组的两个区域对家鸽脚上羽毛的数量和大小有着深远的影响。这些区域包含已知在控制肢体生长以及是否发育成腿或翅膀方面起关键作用的基因。在鸽子胚胎的发育过程中，Domyan等人发现，一种被称为Pitx 1的基因，通常被认为是后肢基因，在长有羽毛的脚的品种的腿中的表达水平低于长有鳞片的脚的品种。实验还表明，在许多动物的前肢中表达的基因Tbx 5在鸽子和长有羽毛脚的鸡的胚胎后肢中表达异常。总之，这些发现表明，在分子水平上，有羽毛脚的家禽的后肢更像翅膀，这导致它们被羽毛而不是鳞片覆盖。未来的工作将旨在发现改变羽足品种中Pitx 1和Tbx 5表达的特定DNA序列，以及相同的基因是否控制其他鸟类的脚羽。DOI：http://dx.doi.org/10.7554/eLife.12115.002网站
Birds display remarkable diversity in the distribution and morphology of scales and feathers on their feet, yet the genetic and developmental mechanisms governing this diversity remain unknown. Domestic pigeons have striking variation in foot feathering within a single species, providing a tractable model to investigate the molecular basis of skin appendage differences. We found that feathered feet in pigeons result from a partial transformation from hindlimb to forelimb identity mediated by cis-regulatory changes in the genes encoding the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also found that ectopic expression of Tbx5 is associated with foot feathers in chickens, suggesting similar molecular pathways underlie phenotypic convergence between these two species. These results show how changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide viable molecular mechanisms for diversity in hindlimb scale and feather distribution. DOI: http://dx.doi.org/10.7554/eLife.12115.001 Animals ranging from fish to birds display dramatic diversity within and among species; yet remarkably little is known about the genetic and developmental mechanisms that underlie this variation. In birds and their extinct dinosaur relatives, the distribution of scales and feathers on the feet is a highly variable trait. Different breeds of domestic pigeon all belong to the same species but have feet that can be feathery or scaly to different extents. Classical genetics experiments suggested that only a few genes are involved in the transition from scaled to feathered skin on the feet of pigeons. However, the molecular basis for this transition was unknown. Domyan et al. set out to identify the genes involved in the transition from scaled to feathered feet by mating different breeds of pigeon in the laboratory and then sequencing the birds’ DNA. They also surveyed the entire DNA sequences of many additional pigeon breeds with and without feathered feet. This combined approach showed that two regions of the pigeon genome have a profound effect on the number and size of feathers on the feet of domestic pigeons. These regions contain genes that are known to play key roles in controlling the growth of a limb and whether it develops into a leg or a wing. In developing pigeon embryos, Domyan et al. found that a gene called Pitx1, which is typically considered a hindlimb gene, is expressed at lower levels in the developing legs of breeds with feathered feet than in a breed with scaled feet. The experiments also showed that Tbx5, a gene that is expressed in the forelimbs of many animals, is expressed abnormally in the embryonic hindlimbs of breeds of pigeon and chicken with feathery feet. Together, these findings suggest that the hindlimbs of domestic birds with feathery feet are more like wings at the molecular level, which results in them being covered in feathers rather than scales. Future work will now aim to discover the specific DNA sequences that alter the expression of Pitx1 and Tbx5 in feather-footed breeds, and whether the same genes control the foot feathers of other species of birds. DOI: http://dx.doi.org/10.7554/eLife.12115.002