More sex chromosomes than autosomes in the Amazonian frog Leptodactylus pentadactylus
More sex chromosomes than autosomes in the Amazonian frog Leptodactylus pentadactylus
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DOI：
10.1007/s00412-018-0663-z
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发表时间：
2018-06-01
期刊：
影响因子：
1.6
通讯作者：
Parise-Maltempi, P. P.
中科院分区：
文献类型：
--
作者：
Gazoni, T.;Haddad, C. F. B.;Parise-Maltempi, P. P.
异形性染色体在真核生物中很常见，在鸟类和哺乳动物中也普遍存在。当今已知脊椎动物中数量最多的多条性染色体是在单孔类鸭嘴兽（Ornithorhynchus anatinus，2n = 52）中发现的，它恰好具有 10 条性染色体。有趣的是，鱼类、两栖动物和爬行动物的性别决定机制涉及或不涉及形态分化的性染色体。相对较少的两栖动物物种携带异形性染色体，并且当存在时，它们通常仅由一对代表，即 XX:XY 或 ZZ:ZW 类型。相比之下，我们通过经典和分子细胞遗传学分析的多项证据，在巴西烟熏丛林蛙种群中发现了 12 条性染色体，命名为 Leptodactylus pentadactylus Laurenti, 1768（Leptodactylinae），其核型为 2n = 22 条染色体。雄性表现出惊人的稳定环形减数分裂链，由六条X和六条Y染色体组成。性染色体的数量比发现的常染色体的数量还要多，这些数据代表了脊椎动物物种中迄今为止发现的最大数量的多性染色体。此外，序列和核型变异数据表明，该物种可能代表了一个物种复合体，其中染色体重排可能在进化过程中发挥了重要作用。
Heteromorphic sex chromosomes are common in eukaryotes and largely ubiquitous in birds and mammals. The largest number of multiple sex chromosomes in vertebrates known today is found in the monotreme platypus (Ornithorhynchus anatinus, 2n = 52) which exhibits precisely 10 sex chromosomes. Interestingly, fish, amphibians, and reptiles have sex determination mechanisms that do or do not involve morphologically differentiated sex chromosomes. Relatively few amphibian species carry heteromorphic sex chromosomes, and when present, they are frequently represented by only one pair, either XX:XY or ZZ:ZW types. Here, in contrast, with several evidences, from classical and molecular cytogenetic analyses, we found 12 sex chromosomes in a Brazilian population of the smoky jungle frog, designated as Leptodactylus pentadactylus Laurenti, 1768 (Leptodactylinae), which has a karyotype with 2n = 22 chromosomes. Males exhibited an astonishing stable ring-shaped meiotic chain composed of six X and six Y chromosomes. The number of sex chromosomes is larger than the number of autosomes found, and these data represent the largest number of multiple sex chromosomes ever found among vertebrate species. Additionally, sequence and karyotype variation data suggest that this species may represent a complex of species, in which the chromosomal rearrangements may possibly have played an important role in the evolution process.