Clues on syntenic relationship among some species of Oryzomyini and Akodontini Tribes (Rodentia: Sigmodontinae)

Sigmodontinae rodents represent one of the most diverse and complex components of the mammalian fauna of South America. Among them most species belongs to Oryzomyini and Akodontini tribes. The highly specific diversification observed in both tribes is characterized by diploid complements, which vary from 2n=10 to 86. Given this diversity, a consistent hypothesis about the origin and evolution of chromosomes depends on the correct establishment of synteny analyzed in a suitable phylogenetic framework. The chromosome painting technique has been particularly useful for identifying chromosomal synteny. In order to extend our knowledge of the homeological relationships between Akodontini and Oryzomyini species, we analyzed the species Akodon montensis (2n=24) and Thaptomys nigrita (2n=52) both from the tribe Akodontini, with chromosome probes of Hylaeamys megacephalus (2n=54) of the tribe Oryzomyini. The results indicate that at least 12 of the 26 autosomes of H. megacephalus show conserved synteny in A. montensis and 14 in T. nigrita. The karyotype of Akodon montensis, as well as some species of the Akodon cursor species group, results from many chromosomal fusions and therefore the syntenic associations observed probably represent synapomorphies. Our finding of a set of such associations revealed by H. megacephalus chromosome probes (6/21; 3/25; 11/16/17; and, 14/19) provides phylogenetic information for both tribes. An extension of these observations to other members of Akodontini and Oryzomyini tribes should improve our knowledge about chromosome evolution in both these groups.Fil: Suarez, Pablo. Universidad Federal de Pará; BrasilFil: Nagamachi, Cleusa Yoshiko. Universidad Federal de Pará; BrasilFil: Lanzone, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Misiones. Facultad de Humanidades y Ciencias Sociales. Departamento de Genética. Laboratorio de Genética Evolutiva y Molecular; ArgentinaFil: Malleret, Matias Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Misiones. Facultad de Humanidades y Ciencias Sociales. Departamento de Genética. Laboratorio de Genética Evolutiva y Molecular; ArgentinaFil: O'Brien, Patricia Caroline Mary. University of Cambridge; Reino UnidoFil: Ferguson Smith, Malcolm Andrew. University of Cambridge; Reino UnidoFil: Pieczarka, Julio Cesar. Universidad Federal de Pará; Brasi

Ideograms of <i>Akodon montensis</i> (A), <i>Thaptomys nigrita</i> (B), and <i>Cerradomys langguthi</i> (C), showing chromosome homologies to <i>Hylaeamys megacephalus</i> (left black numbers) and <i>Akodon paranaensis</i> (right green numbers).

<p>Red stars show regions without complementarity with the probes used. Scale shows the percent relative size of chromosome pairs. (Adapted from Ventura et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143482#pone.0143482.ref012" target="_blank">12</a>], and Nagamachi et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143482#pone.0143482.ref017" target="_blank">17</a>]).</p

Hybridization <i>in situ</i> experiments with chromosome-specific probes of <i>Hylaemys megacephalus</i> hybridized to metaphase chromosomes of <i>Akodon montensis</i> (a, b, c, d and e) and <i>Thaptomys nigrita</i> (f) showing syntenic associations.

<p>Yellow numbers indicating each matching chromosome pair on target species. Bar = 10 μm.</p

Total number and location of FISH signals observed on <i>Akodon montensis</i> and <i>Thaptomys nigrita</i> with specific-chromosome probes of <i>Hylaeamys megacephalus</i>.

<p>Total number and location of FISH signals observed on <i>Akodon montensis</i> and <i>Thaptomys nigrita</i> with specific-chromosome probes of <i>Hylaeamys megacephalus</i>.</p

Chromosome complements of <i>Akodon montensis</i> and <i>Thaptomys nigrita</i> with regions of homology to chromosome-specific probes of <i>Hylaeamys megacephalus</i>.

<p>A-B: G-banded karyotypes. Black-square: C-banded X-chromosomes. Grey-square: C-banded B-chromosome. Bar = 10 μm.</p

Syntenic relationships among several chromosome pairs of <i>Hylaeamys megacephalus</i> (HME), <i>Akodon montensis</i> (AMO), <i>A</i>. <i>paranaensis</i> (APA), <i>Thaptomys nigrita</i> (TNI), and <i>Cerradomys langguthi</i> (CLA) reveled by different chromosome-paint probes (Adapted from Hass et al [15, 16], Ventura et al. [12], and Nagamachi et al. [17]).

<p>Dotted lines: indirectly inferred homology from Ventura et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143482#pone.0143482.ref012" target="_blank">12</a>] data. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143482#sec007" target="_blank">Discussion</a> for details.</p