Chameleons display high karyological diversity in chromosome number (from 2n = 20 to 62), morphology, heterochromatin distribution and location of specific chromosomal markers, making them unique study models in evolutionary cytogenetics. However, most available cytogenetic data are limited to the description of the chromosome number and morphology. Concerning sex chromosomes, our knowledge is limited to ZZ/ZW and Z1Z1Z2Z2/Z1Z2W systems in the genus Furcifer and the isolation of sex-linked, male-specific, sequences in Chamaeleo calyptratus, but the putative XY chromosomes have still to be identified in Chamaeleo and the conservation of male heterogamety in the genus needs confirmation from other species. In this study we performed a molecular and a cytogenetic analysis on C. chamaeleon, using standard, banding methods and molecular cytogenetics to provide a throughout karyological characterization of the species and to identify and locate the putative XY chromosomes. We confirm that the chromosome formula of the species is 2n = 24, with 12 metacentric macrochromosomes, 12 microchromosomes and NORs on the second chromosome pair. Heterochromatin was detected as weak C-bands on centromeric regions, differently from what was previously reported for C. calyptratus. Fluorescence in situ hybridization (FISH) showed the occurrence of interspersed telomeric signals on most macrochromosomes, suggesting that ancient chromosome fusions may have led to a reduction of the chromosome number. Using a combination of molecular and FISH analyses, we proved that male specific Restriction site-Associated DNA sequences (RADseq) isolated in C. calyptratus are conserved in C. chamaeleon and located the putative XY chromosomes on the second chromosome pair. We also identified different transposable elements in the focal taxa, which are highly interspersed on most chromosome pairs.

中文翻译：

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普通变色龙（Chamaeleo chamaeleon）的核学特征为变色龙科性染色体的进化和多样化提供了见解

变色龙在染色体数量（从 2n = 20 到 62）、形态、异染色质分布和特定染色体标记的位置方面表现出高度的核学多样性，使其成为进化细胞遗传学中独特的研究模型。然而，大多数可用的细胞遗传学数据仅限于对染色体数量和形态的描述。关于性染色体，我们的知识仅限于 Furcifer 属的 ZZ/ZW 和 Z1Z1Z2Z2/Z1Z2W 系统，以及 Chamaeleo calyptratus 中性连锁的、雄性特异性序列的分离，但推定的 XY 染色体仍有待在 Chamaeleo 中鉴定并且该属中雄性异配性的保守性需要其他物种的证实。在这项研究中，我们对变色龙进行了分子和细胞遗传学分析，使用标准，条带方法和分子细胞遗传学，以提供物种的完整核学特征，并识别和定位假定的 XY 染色体。我们确认该物种的染色体分子式为 2n = 24，在第二对染色体上有 12 条宏染色体、12 条微染色体和 NOR。异染色质在着丝粒区域被检测为弱 C 带，与先前报道的 C. calyptratus 不同。荧光原位杂交 (FISH) 显示大多数大染色体上散布着端粒信号，这表明古代染色体融合可能导致染色体数量减少。使用分子和 FISH 分析的组合，我们证明了雄性特异性限制位点相关 DNA 序列 (RADseq) 在 C. calyptratus 在 C. chamaeleon 中是保守的，并将假定的 XY 染色体定位在第二对染色体上。我们还在焦点分类群中发现了不同的转座因子，它们高度散布在大多数染色体对上。