Pellegrino K C, Rodrigues M T, Yonenaga-Yassuda Y
Departamento de Biologia, Universidade de São Paulo, Brasil.
Hereditas. 1999;131(1):15-21. doi: 10.1111/j.1601-5223.1999.00015.x.
An extensive karyotype differentiation was found among three species of gymnophthalmid lizard genus Leposoma which occur in the tropical forest areas of Brazil. We examined the chromosomes of the Amazonic species L. guianense (LOU) and L. oswaldoi (LOS) and the Atlantic forest species L. scincoides (LSC) after conventional and differential staining, and FISH of telomeric sequences. Both Amazonic species shared very similar 2n = 44 karyotypes, including 20 biarmed macrochromosomes and 24 microchromosomes (20 M + 24 m). However, the location of Ag-NORs and the amount of constitutive heterochromatin differed in these karyotypes. The Atlantic forest species L. scincoides has a very distinct karyotype with 52 acrocentric and subtelocentric chromosomes of decreasing size. Comparative R-banding analysis revealed complete homeology of the macrochromosomes of LGU and LOS and correspondence of banding patterns between LSC acrocentrics and subtelocentrics and some arms of biarmed LGU and LOS chromosomes. Pair 1 had similar banding patterns in the three species, implying the occurrence of a pericentric inversion. Interstitial telomeric bands (ITBs) detected by FISH at the pericentromeric region of some biarmed LGU and LOS chromosomes could be remnants of chromosomal rearrangements occurred during the differentiation of the karyotypes. Robertsonian rearrangements as well as pericentric inversions events probable were involved in the karyotype evolution of these Amazon and Atlantic forests species of Leposoma.
在巴西热带森林地区发现的三种裸眼蜥属（Leposoma）蜥蜴中，观察到了广泛的核型分化。我们对亚马逊物种圭亚那裸眼蜥（L. guianense，LOU）、奥斯瓦尔多裸眼蜥（L. oswaldoi，LOS）以及大西洋森林物种斯氏裸眼蜥（L. scincoides，LSC）的染色体进行了常规染色、差异染色以及端粒序列的荧光原位杂交（FISH）分析。两种亚马逊物种的核型非常相似，均为2n = 44，包括20条双臂大染色体和24条小染色体（20M + 24m）。然而，这两种核型中银染核仁组织区（Ag-NORs）的位置以及组成型异染色质的数量有所不同。大西洋森林物种斯氏裸眼蜥具有非常独特的核型，由52条大小递减的近端着丝粒和亚端着丝粒染色体组成。比较R带分析显示，圭亚那裸眼蜥和奥斯瓦尔多裸眼蜥的大染色体完全同源，斯氏裸眼蜥近端着丝粒和亚端着丝粒染色体的带型模式与双臂圭亚那裸眼蜥和奥斯瓦尔多裸眼蜥染色体的某些臂相对应。在这三个物种中，第1对染色体具有相似的带型模式，这意味着发生了一次臂间倒位。通过FISH在一些双臂圭亚那裸眼蜥和奥斯瓦尔多裸眼蜥染色体的着丝粒区域检测到的间质端粒带（ITBs）可能是核型分化过程中发生的染色体重排的残余。罗伯逊重排以及臂间倒位事件可能参与了这些亚马逊和大西洋森林地区裸眼蜥物种的核型进化。
