Ventura K, Sato-Kuwabara Y, Fagundes V, Geise L, Leite Y L R, Costa L P, Silva M J J, Yonenaga-Yassuda Y, Rodrigues M T
Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Cytogenet Genome Res. 2012;138(1):19-30. doi: 10.1159/000341887. Epub 2012 Aug 18.
Blarinomys breviceps possesses cryptic and burrowing habits with poorly documented genetics and life history traits. Due to its rarity, only a few specimens and DNA sequences have been deposited in collections worldwide. Here, we present the most comprehensive cytogenetic and molecular characterization of this rare genus. Phylogenetic analyses based on partial cytochrome b sequences were performed, attempting to establish the relationships among individuals with distinct karyotypes along the geographic distribution of the genus in the Atlantic Forest. Classical and molecular cytogenetics, using banding patterns and FISH of telomeric and whole chromosome X-specific painting probes (obtained from the Akodontini Akodon cursor) were used to characterize and compare the chromosomal complements. Molecular phylogenetic analyses recovered 2 main geographically structured clades, northeastern and southeastern with pairwise sequence divergences among specimens varying between 4.9 and 8.4%. Eight distinct karyomorphs are described: (A) 2n = 52 (50A, XX), (B) 2n = 52 (48A, XY+2Bs), (C) 2n = 45 (42A, XY+1B), (D) 2n = 43 (37A, XX+4Bs), (E) 2n = 37 (34A, XY+1B), (F) 2n = 34 (32A, XX), (G) 2n = 31 (27A, XX+2Bs), (H) 2n = 28 (26A, XY), all with the same number of autosomal arms (FN(A) = 50). Variation of 0-4 supernumerary chromosomes (Bs) presenting heterogeneity in morphology and distribution of interstitial telomeric sequences (ITSs) is reported. ITSs are also found in some metacentric autosomes. The phylogeographic separation between 2 major lineages with high levels of genetic divergence, and the wide karyotypic diversity indicate that B. breviceps is a diverse group that warrants taxonomic re-evaluation.
短头布拉鼠具有隐秘和穴居习性，其遗传学和生活史特征的记录很少。由于其稀有性，全球各地的收藏中仅保存了少数标本和DNA序列。在此，我们展示了对这一稀有属最全面的细胞遗传学和分子特征分析。基于细胞色素b部分序列进行了系统发育分析，试图确定在大西洋森林中该属地理分布范围内具有不同核型的个体之间的关系。使用染色体带型以及端粒和全染色体X特异性涂染探针（从阿科东鼠属的阿科东Cursor获得）的荧光原位杂交技术进行经典和分子细胞遗传学分析，以表征和比较染色体组。分子系统发育分析发现了2个主要的地理结构分支，即东北部和东南部，标本之间的成对序列差异在4.9%至8.4%之间。描述了8种不同的核型：(A) 2n = 52 (50A, XX)，(B) 2n = 52 (48A, XY + 2Bs)，(C) 2n = 45 (42A, XY + 1B)，(D) 2n = 43 (37A, XX + 4Bs)，(E) 2n = 37 (34A, XY + 1B)，(F) 2n = 34 (32A, XX)，(G) 2n = 31 (27A, XX + 2Bs)，(H) 2n = 28 (26A, XY)，所有核型的常染色体臂数均相同（FN(A) = 50）。报告了0至4条超数染色体（Bs）的变异，其在形态和间质端粒序列（ITSs）分布上存在异质性。在一些中着丝粒常染色体中也发现了ITSs。两个具有高度遗传分化的主要谱系之间的系统地理分隔以及广泛的核型多样性表明，短头布拉鼠是一个多样化的群体，值得进行分类学重新评估。
