Institute for Applied Ecology, University of Canberra, Canberra 2601, Australia.
BMC Genomics. 2013 Dec 17;14:899. doi: 10.1186/1471-2164-14-899.
Scant genomic information from non-avian reptile sex chromosomes is available, and for only a few lizards, several snakes and one turtle species, and it represents only a small fraction of the total sex chromosome sequences in these species.
We report a 352 kb of contiguous sequence from the sex chromosome of a squamate reptile, Pogona vitticeps, with a ZZ/ZW sex microchromosome system. This contig contains five protein coding genes (oprd1, rcc1, znf91, znf131, znf180), and major families of repetitive sequences with a high number of copies of LTR and non-LTR retrotransposons, including the CR1 and Bov-B LINEs. The two genes, oprd1 and rcc1 are part of a homologous syntenic block, which is conserved among amniotes. While oprd1 and rcc1 have no known function in sex determination or differentiation in amniotes, this homologous syntenic block in mammals and chicken also contains R-spondin 1 (rspo1), the ovarian differentiating gene in mammals. In order to explore the probability that rspo1 is sex determining in dragon lizards, genomic BAC and cDNA clones were mapped using fluorescence in situ hybridisation. Their location on an autosomal microchromosome pair, not on the ZW sex microchromosomes, eliminates rspo1 as a candidate sex determining gene in P. vitticeps.
Our study has characterized the largest contiguous stretch of physically mapped sex chromosome sequence (352 kb) from a ZZ/ZW lizard species. Although this region represents only a small fraction of the sex chromosomes of P. vitticeps, it has revealed several features typically associated with sex chromosomes including the accumulation of large blocks of repetitive sequences.
非鸟类爬行动物性染色体的基因组信息很少，只有少数蜥蜴、几种蛇和一种海龟物种有相关信息，而且这些信息只代表这些物种总性染色体序列的一小部分。
我们报告了来自蜥蜴目爬行动物 Pogona vitticeps 的性染色体的 352kb 连续序列，该物种具有 ZZ/ZW 性微染色体系统。该序列包含五个编码蛋白的基因(oprd1、rcc1、znf91、znf131、znf180)，以及大量重复序列家族，其中包括大量 LTR 和非 LTR 反转录转座子，包括 CR1 和 Bov-B LINEs。这两个基因，oprd1 和 rcc1 是同源同线性块的一部分，在羊膜动物中保守。虽然 oprd1 和 rcc1 在羊膜动物的性别决定或分化中没有已知的功能，但哺乳动物和鸡的这个同源同线性块也包含 R 分泌蛋白 1(rspo1)，即哺乳动物的卵巢分化基因。为了探索 rspo1 是否在石龙子中决定性别，我们使用荧光原位杂交技术对基因组 BAC 和 cDNA 克隆进行了定位。它们位于常染色体微染色体对上，而不是 ZW 性微染色体上，这排除了 rspo1 作为 P. vitticeps 性别决定基因的可能性。
我们的研究对来自 ZZ/ZW 蜥蜴物种的最大连续物理映射性染色体序列(352kb)进行了特征描述。尽管该区域仅代表 P. vitticeps 性染色体的一小部分，但它揭示了几个通常与性染色体相关的特征，包括大量重复序列块的积累。
