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

Different cytotypes in fi shes of the genus Hypostomus Lcépède, 1803, (Siluriformes: Loricariidae) from Xingu river (Amazon region, Brazil)

We analyzed the karyotypes of three specimens of fi shes of the genus Hypostomus Lacépède, 1803 (Loricaridae) from Xingu River (Amazon region). We used conventional staining techniques, including C-banding, Ag-NOR staining, CMA3- and DAPI-banding. Each specimen had a different cytotype: Hypostomus sp. Xingu-1 had 2n=64 (32M/SM, 32ST/A); Hypostomus sp. Xingu-2 has 2n=66 (32M/SM, 34ST/A), and Hypostomus sp. Xingu-3 had 2n=65 (38M/SM, 26ST/A + 1 B). The three cytotypes showed similar C-, CMA3- and DAPI-banding patterns. The nucleolus organizing regions were located in the short arm of chromosome pair 25 of Hypostomus sp. Xingu-1 and pair 29 of Hypostomus sp. Xingu-2, and in the long arm of pair 30 of Hypostomus sp. Xingu-3, probably because of a pericentric inversion. A fusion/fi ssion rearrangement explains the difference in the diploid number and number of M/SM and ST/A chromosomes between the 2n= 64 and 2n=66 cytotypes. The B chromosome most probably explains the difference between the 2n= 64 and 2n=65 cytotypes. The cytotype with 2n=65 had a signifi cantly larger number of M/SM chromosomes, probably because of pericentric inversions. These three cytotypes may represent different species. © Comparative Cytogenetics

Chromosomal evolution and phylogeny in the Nullicauda group (Chiroptera, Phyllostomidae): evidence from multidirectional chromosome painting.

BACKGROUND: The family Phyllostomidae (Chiroptera) shows wide morphological, molecular and cytogenetic variation; many disagreements regarding its phylogeny and taxonomy remains to be resolved. In this study, we use chromosome painting with whole chromosome probes from the Phyllostomidae Phyllostomus hastatus and Carollia brevicauda to determine the rearrangements among several genera of the Nullicauda group (subfamilies Gliphonycterinae, Carolliinae, Rhinophyllinae and Stenodermatinae). RESULTS: These data, when compared with previously published chromosome homology maps, allow the construction of a phylogeny comparable to those previously obtained by morphological and molecular analysis. Our phylogeny is largely in agreement with that proposed with molecular data, both on relationships between the subfamilies and among genera; it confirms, for instance, that Carollia and Rhinophylla, previously considered as part of the same subfamily are, in fact, distant genera. CONCLUSIONS: The occurrence of the karyotype considered ancestral for this family in several different branches suggests that the diversification of Phyllostomidae into many subfamilies has occurred in a short period of time. Finally, the comparison with published maps using human whole chromosome probes allows us to track some syntenic associations prior to the emergence of this family

CARACTERIZAÇÃO CITOGENÉTICA DE UMA ESPÉCIE DE Spatuloricaria (SILURIFORMES, LORICARIIDAE) DO RIO XINGU, (PARÁ, AMAZÔNIA, BRASIL)

Genus Spatuloricaria (Loricariinae, Loricariidae) comprises 12 species which are not very precisely characterized, because morphological data are incipient and no karyotype information is available. In this work, was made the first cytogenetic characterization of a Spatuloricaria species of the Xingu River. Chromosomes were analyzed with conventional staining techniques, C banding, CMA3, DAPI, fluorescent in situ hybridization (FISH) with telomeric probes and rDNA18S. The results show that Spatuloricaria sp. has 2n=66 (6st/7sm/4m/16a) and a fundamental number (FN) of 92. The C-banding pattern revealed a distribution of heterochromatin in the centromeric and pericentromeric regions of the chromosomes and on the short arm of pair 15, coinciding with the DAPI labeling. FISH with rDNA 18S probes painted the terminal portion of chromosome pair eigth, corresponding to the CMA3 labeling, and a heteromorphism between the genomic blocks of this region was observed. The data obtained shall serve as cytotaxonomic markers for a better understanding of this group and its relationships within family Loricariidae, allowing inferences about the chromosomal evolution of the genus and its relations with other loricarids.Keywords: Loricariinae; cytotaxonomy; FISH; rDNA and telomeric probes.O gênero Spatuloricaria (Loricariinae, Loricariidae) compreende 12 espécies com caracterização pouco precisa, com dados morfológicos insipientes e nenhuma informação cariotípica disponível. Neste trabalho foi feita a primeira caracterização citogenética de uma espécie de Spatuloricaria do rio Xingu, utilizando técnicas de coloração convencional, bandeamento C, CMA3, DAPI, hibridização in situ fluorescente (FISH) com sondas teloméricas e DNAr18S. Os resultados mostram que Spatuloricaria sp. apresenta 2n=66 (6st+7sm+4m+16a) e número fundamental (NF) 92. A heterocromatina constitutiva (HC) está presente nas regiões centroméricas e pericentroméricas dos cromossomos e no braço curto do par 15, coincidindo com as marcações de DAPI. A FISH com sondas de DNAr 18S marcou o par cromossômico oito em sua porção terminal correspondente à marcação de CMA3, sendo observado heteromorfismo de tamanho dessa região. Não foram observadas sequências teloméricas intersticiais. Estes dados poderão servir como marcadores citotaxonômicos para a melhor compreensão do grupo e suas relações dentro da família Loricariidae, permitindo traçar inferências sobre a evolução cromossômica do gênero e suas relações com outros loricarídeos.Palavras-chave: Loricariinae, citotaxonomia, FISH, sondas DNAr, sequências teloméricas

Karyotypic divergence reveals that diversity in the Oecomys paricola complex (Rodentia, Sigmodontinae) from eastern Amazonia is higher than previously thought.

The genus Oecomys (Rodentia, Sigmodontinae) is distributed from southern Central America to southeastern Brazil in South America. It currently comprises 18 species, but multidisciplinary approaches such as karyotypic, morphological and molecular studies have shown that there is a greater diversity within some lineages than others. In particular, it has been proposed that O. paricola constitutes a species complex with three evolutionary units, which have been called the northern, eastern and western clades. Aiming to clarify the taxonomic status of O. paricola and determine the relevant chromosomal rearrangements, we investigated the karyotypes of samples from eastern Amazonia by chromosomal banding and FISH with Hylaeamys megacephalus (HME) whole-chromosome probes. We detected three cytotypes for O. paricola: A (OPA-A; 2n = 72, FN = 75), B (OPA-B; 2n = 70, FN = 75) and C (OPA-C; 2n = 70, FN = 72). Comparative chromosome painting showed that fusions/fissions, translocations and pericentric inversions or centromeric repositioning were responsible for the karyotypic divergence. We also detected exclusive chromosomal signatures that can be used as phylogenetic markers. Our analysis of karyotypic and distribution information indicates that OPA-A, OPA-B and OPA-C are three distinct species that belong to the eastern clade, with sympatry occurring between two of them, and that the "paricola group" is more diverse than was previously thought

Chromosome painting in Glyphorynchus spirurus (Vieillot, 1819) detects a new fission in Passeriformes.

Glyphorynchus spirurus (GSP), also called the Wedge-billed Woodcreeper (Furnariidae) has an extensive distribution in the Americas, including the Atlantic coast of Brazil. Nevertheless, there is no information about its karyotype or genome organization. To contribute to the knowledge of chromosomal evolution in Passeriformes we analysed the karyotype of Glyphorynchus spirurus by classic and molecular cytogenetics methods. We show that Glyphorynchus spirurus has a 2n = 80 karyotype with a fundamental number (FN) of 84, similar to the avian putative ancestral karyotype (PAK). Glyphorynchus spirurus pair 1 was heteromorphic in the Tapajós population whereby the short arms varied in sizes, possibly due to a pericentric inversion, as described in other Furnariidae birds. FISH with the Histone H5 probe revealed a signal in the pericentromeric region of G. spirurus chromosome 5 and rDNA 18S showed interstitial signal in GSP-1. Chromosome painting with Gallus gallus (GGA) macrochromosomes 1-9 probes showed disruption of chromosome syntenies of GGA-1, 2 and 4 by fission in Glyphorynchus spirurus. Our results confirm that the GGA1 centric fission is a synapomorphic character for the phylogenetic branch composed of Strigiformes, Passeriformes, Columbiformes and Falconiformes. On the other hand, the GGA-2 fission is reported here for the first time in Passeriformes. Chromosome painting with BOE whole chromosome probes confirmed these rearrangements in Glyphorynchus spirurus revealed by Gallus gallus 1-9 probes, in addition to enabling the establishment of genome-wide homology map

Chromosomal Signatures Corroborate the Phylogenetic Relationships within Akodontini (Rodentia, Sigmodontinae).

Comparative chromosome-painting analysis among highly rearranged karyotypes of Sigmodontinae rodents (Rodentia, Cricetidae) detects conserved syntenic blocks, which are proposed as chromosomal signatures and can be used as phylogenetic markers. In the Akodontini tribe, the molecular topology (Cytb and/or IRBP) shows five low-supported clades (divisions: "Akodon", "Bibimys", "Blarinomys", "Oxymycterus", and "Scapteromys") within two high-supported major clades (clade A: "Akodon", "Bibimys", and "Oxymycterus"; clade B: "Blarinomys" and "Scapteromys"). Here, we examine the chromosomal signatures of the Akodontini tribe by using Hylaeamys megacephalus (HME) probes to study the karyotypes of Oxymycterus amazonicus (2n = 54, FN = 64) and Blarinomys breviceps (2n = 28, FN = 50), and compare these data with those from other taxa investigated using the same set of probes. We strategically employ the chromosomal signatures to elucidate phylogenetic relationships among the Akodontini. When we follow the evolution of chromosomal signature states, we find that the cytogenetic data corroborate the current molecular relationships in clade A nodes. We discuss the distinct events that caused karyotypic variability in the Oxymycterus and Blarinomys genera. In addition, we propose that Blarinomys may constitute a species complex, and that the taxonomy should be revised to better delimit the geographical boundaries and their taxonomic status

Cytogenetic analysis on pterophyllum scalare (perciformes, cichlidae) from jari river, pará state

Cytogenetic studies were carried out on eighteen wild specimens of Pterophyllum scalare from Jari River, in Pará state, and the results were compared to literature. Mitotic chromosomes were obtained from kidney cells and the analysis was done using: C-banding, Ag-NOR staining, Chromomycin A3/DAPI sequential staining and fluorochrome in situ hybridization with human telomere probes. All individuals showed a chromosome number of 2n = 48 (12 M/SM and 36 ST/A) and FN = 60. No differences were detected between male and female karyotypes, indicating the absence of morphologically differentiated mitotic sexual chromosomes. Constitutive heterochromatin blocks were located at the centromeric and pericentromeric regions of all chromosomes. The largest submetacentric pair showed a differential staining on their short arms. Only two NOR bearing chromosomes were detected, and the stainings were observed at the distal region of the short arm of the largest chromosome pair, matching the secondary constriction. Chromomycin A3, stained the NOR and the centromeres of some chromosomes. DAPI-bands were observed at the centromeric regions of all chromosomes. Telomere sequences hybridised only at the terminal regions. © 2006 Taylor and Francis Group, LLC

Chromosomal phylogeny and comparative chromosome painting among Neacomys species (Rodentia, Sigmodontinae) from eastern Amazonia

Abstract: Background: The Neacomys genus is predominantly found in the Amazon region, and belongs to the most diverse tribe of the Sigmodontinae subfamily (Rodentia, Cricetidae, Oryzomyini). The systematics of this genus and questions about its diversity and range have been investigated by morphological, molecular (Cytb and COI sequences) and karyotype analysis (classic cytogenetics and chromosome painting), which have revealed candidate species and new distribution areas. Here we analyzed four species of Neacomys by chromosome painting with Hylaeamys megacephalus (HME) whole-chromosome probes, and compared the results with two previously studied Neacomys species and with other taxa from Oryzomyini and Akodontini tribes that have been hybridized with HME probes. Maximum Parsimony (MP) analyses were performed with the PAUP and T.N.T. software packages, using a non-additive (unordered) multi-state character matrix, based on chromosomal morphology, number and syntenic blocks. We also compared the chromosomal phylogeny obtained in this study with molecular topologies (Cytb and COI) that included eastern Amazonian species of Neacomys, to define the phylogenetic relationships of these taxa. Results: The comparative chromosome painting analysis of the seven karyotypes of the six species of Neacomys shows that their diversity is due to 17 fusion/fission events and one translocation, pericentric inversions in four syntenic blocks, and constitutive heterochromatin (CH) amplification/deletion of six syntenic autosomal blocks plus the X chromosome. The chromosomal phylogeny is consistent with the molecular relationships of species of Neacomys. We describe new karyotypes and expand the distribution area for species from eastern Amazonia and detect complex rearrangements by chromosome painting among the karyotypes. Conclusions: Our phylogeny reflects the molecular relationships of the Akodontini and Oryzomyini taxa and supports the monophyly of Neacomys. This work presents new insights about the chromosomal evolution of this group, and we conclude that the karyotypic divergence is in accord with phylogenetic relationships