Oliveira Da Silva Willam, Pieczarka Julio Cesar, Ferguson-Smith Malcolm Andrew, O'Brien Patricia Caroline Mary, Mendes-Oliveira Ana Cristina, Sampaio Iracilda, Carneiro Jeferson, Nagamachi Cleusa Yoshiko
Centro de Estudos Avançados da Biodiversidade, Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Belém, Brasil.
Cambridge Resource Centre for Comparative Genomics, Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom.
PLoS One. 2017 Aug 1;12(8):e0182218. doi: 10.1371/journal.pone.0182218. eCollection 2017.
The Neacomys genus (Rodentia, Sigmodontinae) is distributed in the Amazon region, with some species limited to a single endemic area, while others may occur more widely. The number of species within the genus and their geographical boundaries are not known accurately, due to their high genetic diversity and difficulties in taxonomic identification. In this work we collected Neacomys specimens from both banks of the Tapajós River in eastern Amazon, and studied them using chromosome painting with whole chromosome probes of Hylaeamys megacephalus (HME; Rodentia, Sigmodontinae), and molecular analysis using haplotypes of mitochondrial genes COI and Cytb. Chromosome painting shows that Neacomys sp. A (NSP-A, 2n = 58/FN = 68) and Neacomys sp. B (NSP-B, 2n = 54/FN = 66) differ by 11 fusion/fission events, one translocation, four pericentric inversions and four heterochromatin amplification events. Using haplotypes of the concatenated mitochondrial genes COI and Cyt b, Neacomys sp. (2n = 58/FN = 64 and 70) shows a mean divergence of 6.2% for Neacomys sp. A and 9.1% for Neacomys sp. B, while Neacomys sp. A and Neacomys sp. B presents a medium nucleotide divergence of 7.4%. Comparisons were made with other published Neacomys data. The Tapajós and Xingu Rivers act as geographic barriers that define the distribution of these Neacomys species. Furthermore, our HME probes reveal four synapomorphies for the Neacomys genus (associations HME 20/[13,22]/4, 6a/21, [9,10]/7b/[9,10] and 12/[16,17]) and demonstrate ancestral traits of the Oryzomyini tribe (HME 8a and 8b, 18 and 25) and Sigmodontinae subfamily (HME 15 and 24), which can be used as taxonomic markers for these groups.
尼氏鼠属（啮齿目，棉鼠亚科）分布于亚马逊地区，有些物种局限于单一的特有区域，而其他物种的分布可能更为广泛。由于该属物种具有高度的遗传多样性以及分类鉴定困难，其物种数量和地理边界尚不清楚。在本研究中，我们从亚马逊东部塔帕若斯河两岸采集了尼氏鼠标本，并使用大头长吻鼠（Hylaeamys megacephalus，HME；啮齿目，棉鼠亚科）的全染色体探针进行染色体涂染分析，以及利用线粒体基因COI和Cytb的单倍型进行分子分析。染色体涂染结果显示，尼氏鼠A种（NSP - A，2n = 58/FN = 68）和尼氏鼠B种（NSP - B，2n = 54/FN = 66）在11次融合/分裂事件、1次易位、4次臂间倒位和4次异染色质扩增事件上存在差异。利用串联线粒体基因COI和Cytb的单倍型分析，尼氏鼠种（2n = 58/FN = 64和70）与尼氏鼠A种的平均分歧度为6.2%，与尼氏鼠B种的平均分歧度为9.1%，而尼氏鼠A种和尼氏鼠B种之间的核苷酸平均分歧度为7.4%。我们还与其他已发表的尼氏鼠数据进行了比较。塔帕若斯河和欣古河构成了界定这些尼氏鼠物种分布的地理屏障。此外，我们的HME探针揭示了尼氏鼠属的四个共衍征（HME 20/[13,22]/4组合、6a/21组合、[9,10]/7b/[9,10]组合和12/[16,17]组合），并展示了稻鼠族（HME 8a和8b、18和25）以及棉鼠亚科（HME 15和24）的祖先特征，这些特征可作为这些类群的分类标记。
