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A depressão é um transtorno mental frequente e vários estudos mostram que os estudantes de medicina são mais suscetíveis. O objetivo deste trabalho foi verificar a presença de sintomas depressivos em estudantes de medicina da Universidade Abierta Interamericana, Buenos Aires. Foi utilizada a pesquisa científica descritiva e transversal em que o Inventário de Depressão de Beck foi utilizado. A normalidade dos dados foi avaliada com o teste de Kolmogórov-Smirnov e os dados foram comparados com o teste T de Student e o teste U de Mann Whitney. As variáveis qualitativas foram comparadas com o teste exato de Fisher. Não houve diferença significativa em idades, níveis de depressão entre homens e mulheres e na distribuição das frequências do ano estudado. O nível leve foi o mais frequente. Os alunos que vivem com amigos têm uma taxa de depressão moderada menor, e os alunos que vivem em hostel têm um índice mais alto. A porcentagem de alunos que nunca fizeram tratamento psicológico é próxima daqueles que nunca receberam tratamento psiquiátrico.

Fil: Takagui, Fábio Hiroshi. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Dias, Ana Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Olivan Birindelli, José Luís. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología animal y vegetal. Museo de Zoología; Brasil. Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología. Laboratorio de Histología y Genética; Brasil. Fil: Da Rosa, Renata. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. Fil: Lui, Roberto Laridondo. Universidad del Oeste de Paraná. Centro de Ciencias Biológicas y de la Salud. Laboratorio de Citogenética; Brasil. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética. Laboratorio de Citogenética General; Argentina. Fil: Giuliano-Caetano, Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General. Laboratorio de Citogenética Animal; Brasil. The family Doradidae (Siluriformes) is an important group of fishes endemic to freshwater ecosystems in South America. Some cytogenetic studies have been conducted focused on the group; however, there are no reports on the occurrence of B chromosomes for the family. In this paper the chromosomal characteristics of Platydoras armatulus (Valenciennes, 1840), Pterodoras granulosus (Valenciennes, 1821) and Ossancora punctata (Kner, 1855) were investigated through classical cytogenetics approaches. The conventional staining reveals 2n=58 in Platydoras armatulus and Pterodoras granulosus, however with distinct karyotypic formulae, possibly originated by pericentric inversions. In Ossancora punctata a derivate karyotype was described with 2n=66 and predominance of acrocentric chromosomes. The C banding pattern was resolutive in discriminating the three species, being considered an important cytotaxonomic marker. All species showed B chromosomes totally heterochromatic with non-Mendelian segregation during meiosis and low frequencies in mitotic cells. The probably origin of these additional elements was through fragmentations of chromosomes of the standard complement, which occurred recently and independently in these three species. The diploid number observed in O. punctata is an evidence of centric fusions and up to the moment it is the highest diploid number reported for Doradidae.

Fil: Gonzalez Gouveia, Juceli. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General; Brasil. Fil: Oliveira de Moraes-Manécolo, Vivian Patrícia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General; Brasil. Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología; Brasil. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina. Fil: Giuliano-Caetano, Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General; Brasil. Fil: Dias, Ana Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Biología General; Brasil. Several neotropical Siluriformes groups suffered important taxonomic revisions based on the evaluation of morphological and molecular characteristics that allow the construction of new phylogenetic hypothesis. In the present study were cytogenetically analyzed six species belonging to Heptapteridae (Cetopsorhamdia iheringi, Phenacorhamdia tenebrosa, Rhamdella eriarcha, Pimelodella meeki, Pimelodella australis, Heptapterus mustelinus) and two to Pseudopimelodidae families (Microglanis cottoides and Microglanis cibelae) by means of differential staining techniques to describe more precisely cytogenetic similarities and differences. The diploid number of R. eriarcha with 2n = 58 and M. cibelae with 2n = 56 were reported for the first time. Also, the lowest chromosome number (2n = 48) for P. tenebrosa was described. The chromosome-banding techniques for to put in evidence nucleolar organizers impregnated by silver nitrate ([AgNORs], chromomycin A3 [CMA3], and rDNA 18S) showed for all studied species conserved patterns, characteristic for each family. The rDNA 5S showed high variability among species or populations of both families, these regions could be simple or multiple, syntenic, or not with rDNA18S. The chromosome markers showed that both families are related not only from a morphologic point of view but also by their karyotypic characteristics, however, some of the present cytogenetic results evidence the importance of new morphologic, molecular, and phylogenetic studies to improve the knowledge of these fish groups.

Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología; Brasil. Fil: Dias, Ana Lucia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología; Brasil. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina. Fil: Fenocchio, Alberto Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico (Nordeste). Instituto de Biología Subtropical; Argentina. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Biología Subtropical; Argentina. The objective of this study was to cytogenetically analyze Phractocephalus hemioliopterus comparing the findings with other data to infer relationships among Pimelodidae species. The results revealed a diploid number of 2n = 56 and the karyotype composed of 16 metacentric, 20 submetacentric, 6 subtelocentric and 14 acrocentric chromosomes (FN = 98). The Ag-NORs, 18S rDNA and CMA3 signals were coincident in location occupying the short arm of an acrocentric chromosome pair (23th), in a secondary constriction. The 5S rDNA genes were localized near the centromere on the short arms of one submetacentric chromosome pair. C-bands were localized predominantly in the terminal regions of chromosomes, including the AgNORs and a small metacentric pair with a conspicuous positive band on interstitial region. This chromosome pair could be considered a species-specific cytogenetic marker.

Fil: Grassi, Diego Javier. The Scripps Research Institute. Department of Molecular Therapeutics; United States. Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología; Brasil. Fil: Abdala Dergam, Jorge. Universidad Federal de Viçosa. Departamento de Biología Animal; Brasil. Fil: Pastori, María Cristina. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina. Fil: Pastori, María Cristina. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Biología Subtropical; Argentina. Fil: Pastori, María Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico (Nordeste). Instituto de Biología Subtropical; Argentina. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Biología Subtropical; Argentina. Fil: Fenocchio, Alberto Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico (Nordeste). Instituto de Biología Subtropical; Argentina. Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydrographic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C- and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromosomes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias malabaricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore, this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.

The Potamotrygonidae family represents the only freshwater group of specialized elasmobranchs and is composed of 4 genera: Plesiotrygon, Paratrygon, Potamotrygon, and Heliotrygon. Individuals of Potamotrygon motoro were collected from the Paraná River at Ituzaingó (Province of Corrientes) in Argentina. Mitotic preparations were obtained using direct techniques and lymphocyte cultures. Chromosomes were studied with conventional Giemsa, C-band and nucleolus organizer region stainings. The diploid number and karyotype formulae were 2n = 66 with 33 homomorphic pairs (14M + 16SM + 22ST + 14A) in females and 2n = 65 with 31 homomorphic pairs plus 3 heteromorphic chromosomes (13M + 15SM + 23ST + 14A) in males. Heterochromatin was distributed at the pericentromeric regions of almost all chromosomes and in the telomeric and interstitial positions of some chromosomes. nucleolus organizer regions were multiple and located at telomeric regions. Because of the clear karyotype differences between the 2 sexes and the presence of 3 unpaired chromosomes in males, it is possible to suggest the occurrence of a multiple sex chromosome system, with male heterogamety (X1X1X2X2/X1X2Y). Further cytogenetic studies are required to develop a hypothesis about the origin of the multiple sex chromosome system in P. motoro.

Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydrographic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C- and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromosomes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias malabaricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore, this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.

In this work, 2 species of the Pimelodidae family, Luciopimelodus pati and Pinirampus pirinampu, were cytogenetically analyzed. Specimens collected from the Parana River, near Corrientes city, Argentina, were assessed using conventional Giemsa, C-banding, and AgNOR staining. L. pati and P. pirinampu showed 2n=50 chromosomes. The cytogenetic characteristics of the 2 species could be considered as derivate features with respect to the other Pimelodinae fishes. Chromosome fusions and chromatin loss are proposed as the hypothetical origin of the described karyotypes.

Karyotype macrostructure and nucleolar organizer regions have often been studied in Neotropical siluriform fishes, but data about structural rearrangements and gene mapping are scarce. 5S rDNA is localized and characterized in Sorubiminae species (Steindachneridion melanodermatum and S. scriptum) using fluorescence in situ hybridization, C- and G-banding and restriction enzyme banding (AluI, BamHI and EcoRI). Chromosome mapping of 5S rDNA genes showed only one site located on the short arms of subtelocentric chromosome pair (chromosome 23) in both species, with no apparent polymorphisms. This region is C-positive and shows a clear G-band, having no cleavage sites for the restriction enzymes tested. These genes are not syntenical with the 18S ones and their karyotype location remains conserved in the species studied, appearing as a cytogenetic marker.

Fifty three species (48 species valid) belonging to the Pimelodidae, Heptapteridae and Pseudopimelo- didae families have been studied cytogenetically, and in the present paper the chromosome number, the presence of B chromosomes and other relevant data were examined. The diploid number varies from 2n=42 to 2n=58 and were detected three cases of triploids with 3n=87 in Rhamdia species. The karyotypes show a high fundamental number because there are constituted predominantly by meta/submetacentric chromosomes.

The chromosomes and banding patterns of Steindachneridion sp., a large catfish (Pimelodidae), endemic to the Iguaçu River, Brazil, were analyzed using conventional (C-, G-banding) and restriction enzyme banding methods. The same diploid number (2n = 56) as in other members of the genus and the family was found but the karyotype displayed an XX/XY sex chromosome system. The X chromosome was the smallest submetacentric, while the Y was the largest chromosome in the karyotype. Meiotic analysis showed 27 autosomal bivalents plus one heteromorphic XY bivalent during spermatogenesis. Sex chromosomes had no particular pattern after C-banding but G- and restriction enzyme bandings showed specific banding characteristics. The present finding represents the first report of a well-differentiated and uncommon sex chromosome system in the catfish family Pimelodidae.

We analyzed cytogenetically specimens of Pimelodella meeki from Tibagi River at Limoeiro (LM) and from two tributaries, Couro do Boi (CB) and Gabriel da Cunha (GC) Rivers. All specimens presented 2n = 46 chromosomes, which were the karyotypes composed by 15 pairs metacentric (M) + 6 pairs submetacentric (SM) + 2 pairs subtelocentric (ST). In specimens of GC, CB, and LM, the results of analyses of the nucleolus organizer regions (NORs), done by means of AgNO 3 and CMA 3 staining, showed that they are identical, located in terminal position on the short arm of a SM chromosome pair, and they were observed to be a size heteromorphism in some metaphase plates. FISH with 18S rDNA probe yielded evidence for these regions but not for the size variation, indicating that they are not due to a greater number of NOR cistrons in one of the homologue chromosomes. An interesting characteristic of these regions is that they could appear divided in blocks, as evidenced by all the techniques. This work makes clear the necessity for more deeply systematic studies, because of the confused taxonomic situation of the genus Pimelodella.

This paper reports the results of cytogenetic analyses carried out on Porichthys plectrodon using conventional Giemsa staining, C-banding and silver staining techniques. A diploid chromosome count of 2n=44 was observed, consisting of 8 metacentric, 10 submetacentric, 6 subtelocentric and 20 acrocentric chromosomes. Differences in length made it possible to identify homologous chromosomes within the metacentric group. Constitutive heterochromatin was distributed as large pericentromeric blocks in pairs 1 and 2, while the rest of the chromosomes were marked in centromeric regions, some more conspicuously than others. One pair of small-sized acrocentric NOR-bearing chromosomes (21) was identified by the nucleolar regions located terminally on their short arms.

A cytogenetic study was conducted on five species of the genus Pimelodus collected from various regions in Brazil: Pimelodus heraldoi, Pimelodus sp, Pimelodus argenteus, P. maculatus and P. mysteriosus. All the species had 2n=56 chromosomes. AgNOR was found in one pair of subtelocentric (ST) chromosomes with staining at the termi- nal position in all the five species. However, Pimelodus sp, P. heraldoi and P. maculatus showed NOR staining on long arm and P. argenteus and P. mysteriosus showed NOR staining on the short arm. AgNOR size heteromorphism was observed in Pimelodus sp, P. maculatus and P. argenteus. The CMA3 fluorochrome staining pattern in all the spe- cies corresponded with AgNOR sites, also showing heteromorphism, including P. mysteriosus. FISH revealed the presence of one pair of chromosomes with ribosomal cistrons and confirmed the presence of the structural hetero- morphism of these sites, except in P. heraldoi.

Were analysed cytogenetically 53 specimens of Imparfinis aff. schubarti of the basin of the Tibagi river (Parana ´,Brazil). The diploid number of 58 chromosomes was observed and a karyotype of 28M+28SM+2ST with a fundamental number (FN) of 116. The nucleolus organizer regions (NORs) were studied by means of AgNO3 and CMA3 staining, as well as by FISH using an 18S rDNA probe. NORs were found to be located at the interstitial po- sition on the long arm of the first metacentric chromosome pair, corresponding to a secondary constriction observed in the conventional staining. AgNO3 and CMA3 evidenced a size heteromorphism between the NORs of the homolo- gous chromosomes. However, after FISH no difference was observed in the size of the homologous NORs. The first M pair. showed a pale C-banding in the pericentromeric region.

In Pimelodidae fish the available chromosome numbers range from 2n=46 to 2n=63, the value 2n=56 being the most frequent one. In the present paper 6 species belonging to the Rhamdiinae subfamily were analyzed: Rhamdia hilarii, R. quelen, Cetopsorhamdia sp., C. iheringhi, Imparfinis cf. piperatus and Imparfinis aff. schubarti. Chromosome preparations were obtained by direct and short term culture methods from kidney cells and analysed under standard Giemsa staining, C-banding and NOR silver staining. Rhamdia species present a basic karyotype composed by 58 chromosomes and the NORs are located on the short arm of a subtelocentric chromosome pair. Cetopsorhamdia sp., C. iheringhi and Imparfinis aff. schubarti. also shows 2n=58, while I. cf. piperatus is the only analyzed species presenting 2n=56. However, these 4 species show an interstitial NOR location. These chromosomal data agree with the occurrence of subgroups in the Rhamdiinae subfamily, proposed on the basis of their morphological traits.

Conventional karyotype and nucleolar organizer regions (NORs) of C. macropomum x P. brachypomus hybrids and parental species are reported. A modal diploid number of 54 chromosomes and a fundamental number (NF) of 108 were found for C. macropomum, P. brachypomus and their hybrids. P. brachypomus shows a pair of silver stained chromosomes, while cells with three and four Ag-NOR bearing chromosomes were observed in C. macropomum. The hybrids consistently presented cells with a single metacentric Ag-NOR bearing chromosome and cells with three Ag-NOR bearing chromosomes. The FISH technique was employed to localize 18S rDNA in the chromosomes of the parentals and the hybrids. In P. brachypomus the FITC signals appeared in the SM pair as when stained with silver salts. In C. macropomum the signals were evidenced in six chromosomes. In the hybrids, as expected, the FITC dots were observed in four chromosomes. All the techniques employed in the present work represent good tools to identify the parentals a...

Seventeen specimens of Pimelodella aff. avanhandavae from the Tibagi River (Parana state, Brazil) were analyzed. The diploid number of 52 chromosomes was observed and the karyotype was composed by 30M and 22SM with fundamental number (FN) of 104. Results of analyses of the nucleolus organizer regions (NORs), obtained by AgNO3 and CMA3, staining and FISH with 18S rDNA probe showed fluorescence in a terminal position on the short arm of a pair of subtelocentric chromosomes. The C-banding regions were evidenced weakly in telomeric and centromeric regions and some chromosomes present conspicuous marks, also staining positively the NORs.

The chromosomes of Steindachneridion sp. (2n = 56) and Rhamdia quelen (2n = 58) were analyzed by C-banding (CB) and Chromomycin A3 (CMA3) and 4,6-diamidino-2-phenylindole (DAPI) staining, separately and consecutively, in order to understand the role of base-specific fluorochrome treatment after CB. Both species' chromosomes shared common staining profiles as follows. CB with Giemsa (CBG) revealed weak heterochromatic blocks in the telomeric regions of some chromosomes and conspicuous bands on the short arms of one chromosome pair, where nucleolar organizer regions (NORs) were evidenced by silver-staining. Without CB pretreatment, the NORs were stained conspicuously with CMA3, but not with DAPI. The latter uniformly stained all chromosomes, but leaving the NORs pale. Combination of CMA3 or DAPI staining with CB showed distinctive fluorescent blocks in the NOR-bearing short arms of the single chromosome pair along with several bright fluorescent signals on other chromosomes, which were not evidenced by single CMA3 or DAPI staining. These results suggest a modification of chromatin structure by CB treatment, which may increase the stainability of CMA3 and DAPI.

Cytogenetic studies of A. brasiliensis from the south coast of Brazil were made with specimens of two populations: Baia de Paranagua and Lagoa da Conceicao. All the individuals analyzed presented a diploid number of 48 chromosomes with a standard karyotype constituted by 4M + 10SM + 14ST + 20A (FN=76). There have been found five different cytotypes (A to E) in the specimens of the Baia de Paranagua/PR, while in the Lagoa da Conceicao/SC just two (standard and F). These cytotypes are characterized by changes in the number of M and SM chromosomes and these differences could be due to pericentric inversions. The C-banding regions were evidenced in pericentromeric and telomeric regions also staining positively the secondary constrictions. NORs detected by AgNO3 and CMA3 staining are located at the short arms of acrocentric chromosomes (19th pair) and these techniques evidence a size heteromorphism between the homologue chromosomes. The heteromorphism of the NOR bearing chromosome was not detect by FI...

The synthetic (GA)9+C sequence was used as probe for in situ hybridization in chromosomes of wheat (Triticum aestivum), fishes (Imparfinis schubarti, Steindachneridion scripta, Rineloricaria latirostris), mouse (Akodon nigrita), and frog (Rana catesbiana). Differences were observed in localization and intensity of probe signals among these karyotypes. In wheat, stronger hybridization signals were observed at interstitial regions while weak signals were mainly at sub-centromeric ones. In Imparfinis schubarti, (GA)9+C microsatellite were highly clustered at the telomeric regions of all the chromosomes. In S. scripta they appeared disperse along the chromosome arms but are also observed bright signals at some telomeric regions, and in Rineloricaria latirostris only one chromosome pair shows detectable FITC signal, near to the NORs sites. In R. catesbiana, only few and weak signals were observed at some centromeric and interstitial regions. Akodon nigrita showed hybridization sites on the pericentromeric regions. The (GA)9+C microsatellite varies extensively from species to species in the amount and dispersion patterns, supporting what is already known about families of repeated DNA.

Karyotypic data on Iheringichthys labrosus from several populations of Paraná River/Argentina are presented. The diploid number was 2n=56 and the karyotype consisted of 42m/sm + 14st/a (NF= 98). The AgNORs were observed in telomeres of the long arm of a st/a chromosome pair. These sites were also positive after C-banding. Heterochromatin was observed in the telomeric position in some chromosomal pairs and can be found in one or both metacentric chromosome arms. The obtained results were compared with those reported for different populations from Brazilian rivers and the similarity among them was evident. However, discordant chromosome formulae and karyotype features between samples should be carefully taken because, in some cases, they seem to be more technical artifacts than real differences. Dados cariotípicos de Iheringichthys labrosus de várias populações do Rio Paraná/Argentina são apresentados. O número diploide foi 2n=56 e o cariótipo constituído de 42m/sm + 14st/a (NF= 98). As AgNORs foram observadas telomericamente no braço longo de um par cromossômico st/a. Estes sítios também apresentaram bandas positivas após bandamento C. Heterocromatina foi observada em posição telomérica em alguns pares cromossômicos e podem ser encontradas em um ou ambos os braços de cromossomos metacêntricos. Os resultados obtidos foram comparados com aqueles reportados em diferentes populações de rios brasileiros e foi evidente uma similaridade entre eles. Entretanto, fórmulas cariotípicas discordantes e características cariotípicas entre exemplares deveriam ser cuidadosamente observadas porque, em alguns casos, eles parecem ser mais artefatos de técnica que diferenças reais. Fil: Sánchez, Sebastián. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; Argentina. Fil: Swarça, Ana Claudia Universidade Estadual de Londrina. Centro de Ciências Biológicas. Departamento de Histología; Brasil. Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Departamento de Genética; Argentina.

The ribosomal RNA genes of Pinirampus pirinampu have been localized by fluorescence in situ Hybridization hybridization (FISH) with 18S rDNA probe. This method allowed the location of FITC signals on the short arm of the biggest subtelocentric chromossomic pair and evidenced a size heteromorphism of hybridization signals between homologous chromosomes. This difference has been attributed to variation in the amount of rRNA genes per cluster, probably due structural modifications (i.e. duplications by unequal crossing over or transpositions) of NOR involving homologous segments.

Only 33 species among about 300 belonging to the families Pimelodidae and Rhamdiidae have been studied cytogenetically. The diploid number varies from 2n = 46 to 2n = 63 chromosomes, with the karyotypes often being of the meta/submetacentric type. As a result, there is generally a very elevated fundamental number. No presente trabalho foi realizado um levantamento citogenético de espécies de peixes das famílias Pimelodidae e Rhamdiidae, onde foi observado que das 300 espécies pertencentes a estas famílias, apenas 33 foram caracterizadas citogeneticamente. O número diplóide variou de 2n = 46 a 2n = 63 cromossomos, os cariótipos são freqüentemente assimétricos, com uma predominância de cromossomos do tipo meta/submetacêntricos, resultando portanto, em um número fundamental alto.

Eighteen specimens of Pimelodus maculatus collected from Tibagi River (Sertaneja, PR, Brazil) were analyzed cytogenetically. The diploid number of 56 chromosomes was observed and karyotype was 20 M + 20 SM + 10 ST + 6 A with fundamental number (FN) of 106. Results of analyses from the nucleolus organizer regions (NORs), obtained by AgNO3, CMA3 and C-band staining showed marking in a terminal position on the long arm of a pair of subtelocentric chromosomes. The restriction enzyme AluI produced a linear differentiation similar to C-banding.

Specimens of Pinirampus pirinampu were analyzed cytogenetically. Fifteen individuals were obtained from the Tibagi river near Sertaneja, PR, Brazil. A karyotypic structure consisting of 50 chromosomes distributed as 26M+12SM+2ST+10A was observed. The nucleolar organizing regions ( NORs) were identified on the short arm of a pair of subtelocentric chromosomes. A variation in size of the NOR regions was observed among the paired chromosomes. Chromomycin (CMA 3) staining established not only the nucleolar chromosome pair, but also fluorescent marking in the telomeric and centromeric regions of other chromosomes which seem to correspond to the distribution patterns of the constitutive heterochromatin. Restriction enzyme Alu I was employed and the reaction pattern obtained also corresponded to the heterochromatin constitutive distribution.

Hemisorubim platyrhynchos is a medium- to large-sized pimelodid catfish distributed along several river basins of the Neotropical Region, noteworthy for representing an important fishery source. In this work, H. platyrhynchos from three isolated populations were cytogenetically analyzed. The karyotype shows a diploid number of 2n=56 chromosomes comprising 22m, 16sm, 10st, 8a (FN=104). NORs detected by AgNO3 were located in the terminal regions of the short arm of a st chromosome pair, as confirmed by CMA3 and FISH using an 18S rDNA probe. C-banding revealed a small amount of heterochromatin in chromosomes, including the NORs, and one biarmed pair that showed conspicuous positive bands on both arms. This fact was also evidenced when using other banding techniques, such as RE (AluI), and indicates that this pair constitutes a species-specific cytogenetic marker.

In this work, Bunocephalus doriae was cytogenetically analyzed. A karyotype with a diploid number of 2n= 50 comprising 6m, 10sm, 6st, and 28a (FN= 72) chromosomes was observed. The occurrence of an asymmetric karyotype with a large number of acrocentric chromosomes distinguishes this species from others the Order Siluriformes. An exclusive character observed is the first pair of subtelocentric as the largest chromosome pair of the complement. NORs detected using AgNO3 were located in the terminal regions, on the short arm of a subtelocentric chromosome pair (pair 11), in a secondary constriction. C-banding revealed heterochromatic centromeric regions on several chromosomes of the complement after C-banding. This is the first cytogenetic description of this species and the first cytogenetic report on a member of the family Aspredinidae.No presente trabalho, Bunocephalus doriae. foi analisado citogeneticamente. O número diploide encontrado foi 2n= 50 compreendendo 6m, 10sm, 6st, and 28a (NF= 72) cromossomos. A ocorrência de um cariótipo assimétrico com um grande número de cromossomos acrocêntricos distingue esta espécie das demais pertencentes à Ordem Siluriformes e foi observada como característica exclusiva a presença do primeiro par subtelocêntrico, sendo o maior do complemento. As NORs detectadas pelo AgNO3 foram observadas na região terminal do braço curto de um par cromossômico subtelocêntrico (par 11), em uma constrição secundária. A heterocromatina, após o bandamento C, foi visualizada em regiões centroméricas de vários cromossomos do complemento. Esta é a primeira descrição citogenética desta espécie e a primeira descrição de um membro da família Aspredinidae.

Several cytogenetic techniques (AgNOR, C- G- and RE bandings, DAPI, CMA3 and FISH) were applied in order to analyze the structure and variability of NORs in the fish species Steindachneridion melanodermatum and S. scripta. Ag-NORs were observed on the short arm of the first acrocentric chromosome pair, coincidentally with a strong C-positive band on a large secondary constriction. In addition, NORs showed bright fluorescent signals when stained with CMA3 and treated for FISH with rDNA 18S. However, they showed negative coloration after G- and restriction enzyme banding and DAPI staining. The results evidence a substantial size polymorphism in these regions. The NOR bearing chromosomes in both species may be considered homologues because they maintain conserved characteristics, such as being interspersed with a GC-rich heterochromatin and possessing target sequences for AluI, BamHI and EcoRI.

We present the karyotypic characterization of 26 specimens of the side-necked turtle Hydromedusa tectifera collected in the upper Iguaçu River, Paraná state, Brazil. The turtles were cytogenetically analyzed using Giemsa staining and other banding techniques (C, G, Ag-NOR and CMA3) as well as fluorescence in situ hybridization (FISH) with a rDNA 18S probe. All the specimens showed a diploid number of 58 composed of 22 macro and 36 microchromosomes. The Ag-NOR, CMA3 and FISH techniques permitted the identification and characterization of the chromosome pairs bearing nucleolus organizer regions (NORs), while G-banding facilitated a better recognition and pairing of macrochromosomes. These data agree with some information available in the literature and should be very useful for further cytotaxonomic and cytosystematic studies.

In the present cytogenetic study of Pimelodus maculatus, 13 specimens (8 males and 5 females) from the Congonhas Stream in Paraná State, Brazil, were examined using conventional staining. All of them showed a karyotype of 2n = 56, with a chromosome distribution of 20m + 20sm + 10st + 6a. However, four individuals (2 males and 2 females) were found to have a variant karyotype (cytotype) with two heteromorphic chromosomes in the group of submetacentric chromosomes - one of them corresponds to the second largest chromosome of this group and the other is a chromosome of small size. This variation suggests the existence of a structural polymorphism in the studied population.

A família Doradidae é atualmente constituída por 95 espécies de peixes que ocorrem apenas em ecossistemas dulcícolas da América do Sul, sendo mais abundantes na bacia amazônica, onde desempenham papeis ecológicos fundamentais para a homeostasia do ecossistema. Nas últimas décadas diversos estudos filogenéticos baseados em marcadores morfológicos e moleculares corroboraram o monofiletismo do grupo, entretanto algumas divergências permanecem, principalmente em alguns clados onde a abordagem taxonômica tradicional não foi suficiente para diagnostica-los. Nesse sentido, o presente estudo busca resolver alguns desses problemas taxonômicos, utilizando marcadores citogenéticos associados ao DNA barcoding, assim como propor tendências sobre a evolução cariotípica em Doradidae. Foram analisadas 15 espécies de thorny catfishes, provenientes de diferentes sistemas hidrográficos, os dados obtidos foram distribuídos em três capítulos, cada qual explorando a eficiência dos estudos cariotípicos para compreender questões biogeográficas, citotaxonômicas e evolutivas. O capítulo 1 traz informações sobre as caracteríticas cariotípicas da subfamília Wertheimerinae: Wertheimeria maculata, Kalyptodoras bahiensis e Franciscodoras marmoratus. As três espécies exibiram 2n=58 e a mesma fórmula cromossômica com diferenças apenas no padrão de distribuição dos DNAr e principalmente na disposição dos blocos heterocromáticos. Tal variação microestrutural parece estar relacionada com a atividade saltatória de elementos transponíveis, dentre os quais o retrotransposon Rex3 merece destaque. Também foi sugerida uma hipótese biogeográfica para explicar a diversificação cariotípica de Wertheimerinae, sendo essa baseada em eventos de captura de cabeçeira no Complexo do Espinhaço que proporcionou um dinâmico intercâmbio de ictiofauna entre o rio São Francsisco e a drenagem costeira do Leste. O capítulo 2 trata de questões citaxonômicas, com ênfase no gênero Anadoras, que embora seja um dos mais amplamente distribuídos dentre aqueles alocados em Doradidae, possui apenas duas espécies formalmente descritas: Anadoras grypus e Anadoras weddellii, sendo que no presente estudo o status taxonômico de uma possível nova espécie endêmica do Alto rio Araguaia foi testado, utilizando marcadores citogenéticos e algoritmos de delimitação de espécies baseado no DNA barcoding. Os dados cromossômicos foram eficientes somente para diferenciar A. grypus de seus congeneres, evidenciando uma notável similaridade entre A. weddelli e Anadoras sp. ?araguaia? . Entretanto o DNA barcoding separou claramente as três espécies, identificando três unidades taxonômicas moleculares operacionais (MOTUs), com alto valor de divergência genética e suportadas pelas inferências Bayesianas,Verossimilhança e por todos os algorítmos de delimitação de espécies. Foi observado também uma baixa distância genética entre populações de A. weddelli do Alto, Médio rio Paraguai e Baixo amazonas, sugerindo uma baixa varibilidade entre populações distantes geograficamente. Curiosamente, a distância intraespecífica observada em indivíduos de uma mesma população de A. grypus foi maior do que aquela observada em populações de bacias distintas de A. weddellii, no entanto o valor obtido não suporta a hipótese de espécies crípticas em simpatria no Lago Catalão e sugere que a variação descrita no padrão de NORs é um polimorfismo intrapopulacional. No capítulo 3, inferências evolutivas utilizando o software Mesquite foram propostas para explicar a origem da atual diversidade cariotípica de Doradidae. Nesse estudo, 9 espécies foram analisadas evidenciando uma acentuada variação no número de diplóide: 2n= 44 em Amblydoras nheco, 2n= 46 em Amblydoras affinis, 2n=52 em Astrodoras asterifrons, 2n= 58 em Platydoras hancockii, Pterodoras granulosus, Centrodoras brachiatus, Oxydoras niger, Hemidoras stenopeltis e 2n=60 em Trachtdoras steindachneri. Espécies crípticas foram identificadas em Amblydoras affinis assim como um inédito sistema de NORs múltiplas em P. hancockii. A reconstrução do caracter ancestral corroborou estudos anteriores e estimou como 2n basal 58 cromossomos e NORs simples terminais no braço curto de subtelocêntricos, essas característica permanecem conservadas em diferentes clados de Doradidae, porém cariótipos derivados também ocorrem devido á rearranjos cromossômicos (inversões pericêntricas, Fissão e Fusão cêntrica, Translocações) e também pelo acúmulo diferencial de regiões heterocromáticas. The Family Doradidae is currently composed of 95 species of fish that occur only in South American freshwater ecosystems, most abundantly in the Amazon basin, where they play ecologic roles that are fundamental for the homeostasis of the ecosystem. In the last decades, several phylogenetic studies based on morphological and molecular markers have corroborated the monophyletic nature of the group, however some divergences remain, mainly in some clades where the traditional taxonomic approach was not enough to diagnose them. In this sense, the present study aims to solve some of these taxonomic problems, using cytogenetic markers associated with DNA barcoding, as well as to propose trends on the karyotype evolution in Doradidae. 15 species of thorny catfishes from different hydrographic systems were analysed. The data were divided in three chapters, each of them exploring the efficiency of karyotype studies for better understand biogeographic, cytotaxonomic and evolutionary issues of Doradidae. Chapter 1 provides information on the characteristics of the species of the subfamily Weitheimerinae: Wertheimeria maculata, Kalyptodoras bahiensis and Franciscodoras marmoratus. The three species had 2n=58 chromosomes and the same chromosomal formula with differences only in the distribution pattern of rDNA and specially in the arrangement of the heterochromatin blocks. Such microstructural variation seems to be related to the salutatory activity of transposable elements, among which the retrotransposon Rex3 is worth being highlighted. It was also suggested a biogeographic hypothesis to explain the karyotypic diversification of Wertheimerinae, which is based on River catching events in the Espinhaço Complex and provided a dynamic interchange in the ichthyofauna between São Francisco River and the eastern coastal drainage.Chapter 2 deals with cytotaxonomic issues, with emphasis on the genus Anadoras, which is the most widely distributed among those allocated in Doradidae, however the genus has only two formally described species: Anadoras grypus and Anadoras wedelli, and in the present study the taxonomic status of a possible new endemic species from Upper Araguaia River was tested using cytogenetic markers and DNA delimitation algorithms based on DNA barcoding.The chromosome data were eficiente only to differenciate A. grypus from its congeneres,evidencing a remarkable similarity between A. wedelli and Anadoras sp. ?araguaia?. However, DNA barcoding clearly separated the three species, identifying three molecular operational taxonomic units (MOTUs), with high genetic divergence value and supported by Bayesian inferences, Likelihood and by all algorithms of species delimitation. It was also observed a low genetic distance between populations of A. wedelli from Upper, Middle Paraguay River and Lower Amazonas, suggesting a low variability among populations geographically distant. Interestingly, the intraspecific distance observed in individuals from the same A. grypus population was higher than what was observed in populations from the distant basis of A. wedelli, however the value does not support the hypothesis of cryptic species in sympatri in Lake Catalão and suggest that the variation described for the NORs pattern is an intrapopulational polymorphism. In Chapter 3, evolutionary inferences using the Mesquite software were proposed to explain the origin of the current karyotype diversity in Doradidae. In this study, 9 species were analyzed showing a remarkable variation in the diploid number: 2n = 44 in Amblydoras nheco, 2n = 46 in Amblydoras affinis, 2n = 52 in Astrodoras asterifrons, 2n = 58 in Platydoras hancockii, Pterodoras granulosus, Centrodoras brachiatus, Oxydoras kneri, Hemidoras stenopeltis and 2n = 60 in Trachydoras steindachneri. Cryptic species were identified in Amblydoras affinis as well as an unprecedented system of multiple NORs in P. hancockii. The reconstruction of the ancestral character corroborated previous studies and estimated 2n=58 chromosomes and simple terminal NORs in the short arm of subtelocentric as basal, these characteristics remain conserved in different clades of Doradidae, however it also occurs in derived karyotypes due to chromosomal rearrangements (pericentric inversations, Fission and Centric Fusion and translocations) and also by the differential accumulation of heterochromatic.

Atividades como a construção de barragens, desmatamento, alteração das matas ciliares e introdução de espécies exóticas estão entre as principais causas da desestruturação das comunidades de peixes e fragmentação dos ambientes aquáticos. Essas ações resultaram em uma redução na eficiência do processo de recrutamento de espécies nativas. Com o objetivo de identificar os possíveis fatores responsáveis pelas alterações no padrão de reprodução das espécies e também importantes pontos de desova na bacia do baixo rio Paranapanema nos períodos de 2013, 2014 e 2015, foram realizadas coletas de ovos e larvas em trechos relacionados às barragens das Hidrelétricas de Rosana (1986), Taquaruçu (Escola politécnica-Taquaruçu, 1992) e Capivara (Escola Engenharia Mackenzie, 1975). O material foi quantificado e identificado até o menor grupo taxonômico possível para determinação da composição e distribuição espacial das formas iniciais de desenvolvimento de peixes. Para avaliar quais variáveis ambientais foram significativas no recrutamento das espécies, utilizou-se da análise de componentes principais (PCA) determinou que o pH, a condutividade e a temperatura foram as variáveis abióticas que mais influenciaram a distribuição de ovos e larvas. A análise de coordenadas principais (PCoA) mostrou que Auchenypterus osteomystax , Plagioscion squamosissimus e Tatia neivai foram as espécies que mais influenciaram a separação dos reservatórios, em virtude de conseguirem completar seu ciclo de vida nos pontos estudados. Os resultados obtidos reforçam a necessidade de conservação das áreas de reprodução e crescimento para ampliar a eficiência do recrutamento e também de repensar as atividades de peixamento, visto que as espécies foco desta atividade foram pouco representativas no presente estudo. Activities such as dam construction, deforestation, alteration of riparian forests and the introduction of exotic species are among the main causes of disruption of fish communities and fragmentation of aquatic environments. These actions resulted in a reduction in the efficiency of the recruitment of native species process. In order to identify the possible factors responsible for changes in the pattern of reproduction of the species and also important spawning points in the lower Rio Paranapanema basin in the periods 2013, 2014 and 2015 eggs and larvae were collected in related sections to dams of Hydropower Rosana (1986), Taquaruçu (polytechnic-Taquaruçu School, 1992) and Capybara (Mackenzie Engineering School, 1975). The material was quantified and identified to the lowest possible taxonomic group to determine the composition and spatial distribution of early forms of fish development. To evaluate which environmental variables were significant in the recruitment of species, we used the principal component analysis (PCA) determined that the pH, conductivity and temperature were the abiotic variables that most influenced the distribution of eggs and larvae. The principal coordinates analysis (PCoA) showed that Auchenypterus osteomystax, Plagioscion squamosissimus and Tatia neivai were the species that most influenced the separation of the reservoirs, due to achieve complete their life cycle in point studied. The results reinforce the need for conservation of breeding areas and growth to expand recruitment efficiency and also to rethink the activities of stocking, as the species focus of this activity were unrepresentative in this study.