Friedman-Einat Miriam, Seroussi Eyal
Institute of Animal Science, The Volcani Center, Rishon Le-Zion, Israel.
BMC Genomics. 2014 Jul 3;15(1):551. doi: 10.1186/1471-2164-15-551.
A LEP transcript up-regulated in lungs of ducks (Anas platyrhynchos) infected by avian influenza A virus was recently described in the Nature Genetics manuscript that reported the duck genome. In vertebrates, LEP gene symbol is reserved for leptin, the key regulator of energy balance in mammals.
Launching an extensive search for this gene in the genome data that was submitted to the public databases along with duck genome manuscript and extending this search to all avian genomes in the whole-genome shotgun-sequencing database, we were able to report the first identification of coding sequences capable of encoding the full leptin protein precursor in wild birds. Gene structure, synteny and sequence-similarity (up to 54% identity and 68% similarity) to reptilian leptin evident in falcons (Falco peregrinus and cherrug), tits (Pseudopodoces humilis), finches (Taeniopygia guttata) and doves (Columba livia) confirmed that the bird leptin was a true ortholog of its mammalian form. Nevertheless, in duck, like other domestic fowls the LEP gene was not identifiable.
Lack of the LEP gene in poultry suggests that birds that have lost it are particularly suited to domestication. Identification of an intact avian gene for leptin in wild birds might explain in part the evolutionary conservation of its receptor in leptin-less fowls.
最近在一篇报道鸭基因组的《自然遗传学》论文中描述了一种在感染甲型禽流感病毒的鸭（绿头鸭）肺中上调的LEP转录本。在脊椎动物中，LEP基因符号保留给瘦素，它是哺乳动物能量平衡的关键调节因子。
在与鸭基因组论文一起提交到公共数据库的基因组数据中广泛搜索该基因，并将搜索扩展到全基因组鸟枪法测序数据库中的所有鸟类基因组，我们首次报告了在野生鸟类中能够编码完整瘦素蛋白前体的编码序列的鉴定。在猎鹰（矛隼和草原隼）、山雀（棕颈雪雀）、雀类（斑胸草雀）和鸽子（家鸽）中，基因结构、同线性和与爬行动物瘦素的序列相似性（高达54%的同一性和68%的相似性）表明鸟类瘦素是其哺乳动物形式的真正直系同源物。然而，在鸭中，与其他家禽一样，无法鉴定出LEP基因。
家禽中缺乏LEP基因表明失去该基因的鸟类特别适合驯化。在野生鸟类中鉴定出完整的鸟类瘦素基因可能部分解释了其受体在无瘦素家禽中的进化保守性。
