Navegando por Assunto "Roedor"

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Análise citogenética de duas espécies do gênero Hylaeamys (Rodentia: Cricetidae) por citogenética clássica e molecular
(Universidade Federal do Pará, 2013-04-05) PINTO, Jamilly Amaral; NAGAMACHI, Cleusa Yoshiko; http://lattes.cnpq.br/8887641213110093
Rodents are one of the largest and oldest orders of the class Mammalia. In South America, the order Rodentia compromises about 42% of mammal species, and from this more than 50% belong to the family Cricetidae, which includes the subfamily Sigmodontinae. The genus Hylaeamys is inserted in the tribe Oryzomyini and corresponds to one of 10 new genera proposed for species and species groups within Oryzomys. Hylaeamys is the equivalent of "megacephalus group", and consists of the species H. acritus, H. laticeps, H. megacephalus, H. perenensis, H. oniscus, H. tatei and H. yunganus, distributed in Venezuela, Trinidad, Guyana, Paraguay and Brazil, in areas of the Amazon rain forest, Atlantic rainforest and savannah. This study aims to analyze chromosomal markers in two species of the genus Hylaeamys, providing data to assist in its taxonomic and cytogenetic characterization. Nineteen samples of Hylaeamys megacephalus (HME) and four samples of Hylaeamys oniscus (HON) were analyzed. HME has 2n = 54 and HON, 2n = 52. The results obtained by G- and C-banding and Fluorescent In Situ Hybridization with whole chromosome probes from Hylaeamys megacephalus made it possible to determine the chromosomal characteristics of the species studied, as well as allowing a comparative analysis between them, and in comparison with Cerradomys langguthi, observing homeologies and karyotypic differences. The two species of Hylaeamys differ by a centric fission/fusion rearrangement in which HON shows the association of the pairs 14/19 of HME. This association is shared with CLA with an inversion (19/14/19). This work is an achievement for phylogeny and chromosomal studies on the genus Hylaeamys.
Acesso aberto (Open Access)
Anatomical and histological characteristics of teeth in agouti (Dasyprocta prymnolopha Wagler, 1831)
(2013-12) SILVA, Daiane Claydes Baia da; FAGUNDES, Nathália Carolina Fernandes; TEIXEIRA, Francisco Bruno; PENHA, Nelson Elias Abrahão da; SANTANA, Luana de Nazaré da Silva; OLIVEIRA, Ana Cristina Mendes de; LIMA, Rafael Rodrigues
The agouti species Dasyprocta prymnolopha (D. prymnolopha) is a medium-sized rodent, diurnal, and characteristic of northeastern Brazil, south of the Amazon. Several studies have been made on these rodents. However, there is a lack of analysis of masticatory system, in particular morphology of the teeth. Thus, this research seeks to describe anatomical and histological aspects of the agouti teeth. For this purpose, we used adult agouti, in which measurements and descriptions of teeth and dental tissues were made. It was observed that the dental arch of D. prymnolopha comprises of twenty teeth, evenly distributed in the upper and lower arch, being inferior teeth larger than their corresponding higher. The incisors are larger, and between the posterior premolars and molars, there is a gradual increase in length in the anterior-posterior arch. In microscopic examination, a prismatic appearance was observed consisting of enamel prisms arranged in different directions, behind the enamel and dentin with standard tubular dentinal tubules with variable diameter and far between, also showing a sinuous path from the inner portion to the junction with more superficial enamel. Morphological analysis of dental tissues showed that an enamel with structural organization adapted to the act of chewing and high impact dentin compatible with standard tubular function resilience and mechanical damping of masticatory forces, as found in larger animals, confirming the understanding of eating habits that define much of its ecological functions within the ecosystem they inhabit.
Acesso aberto (Open Access)
Aspectos morfológicos comparativos entre neurônios da camada I do córtex visual de duas espécies de roedores: Cavia porcellus e Rattus norvegicus
(Universidade Federal do Pará, 2014-08-20) MOREIRA, Thayana de Nazaré Araújo; SILVA FILHO, Manoel da; http://lattes.cnpq.br/2032152778116209
The layer I has as main characteristic the low number of neurons and a high density of nerve fibers. The morphology of neurons of layer I is still understudied, so that in studies evaluating the morphology of these neurons has not yet reached a consensus on the forms and functions of these neurons. This study evaluated the morphology of neurons in layer I of the visual cortex of two rodent species: Cavia porcellus, popularly known in Brazil as a guinea pig and Rattus norvegicus, which is the rat and the Wistar strain was used, commonly used in scientific research. The guinea pig is a widely studied animal model used in several areas of science. Although this species is well studied, works on layer I of this animal are relatively rare, especially in relation to morphology and electrophysiology of neurons in this cortical region. Research in rats on neurons of layer I are more frequent, both in relation to morphology and electrophysiology. To discriminate the potential for differences in the morphology of neurons in layer I of the visual cortex of the guinea pig and mouse, this study classified these neurons according to the trajectory of their dendrites and dendritic measures analyzed using the technique of intracellular injection of biocytin. After classification of neurons comparisons were made between the same cell types of each rodent. 35 guinea India Dunkin-Hartley variety of short-haired of both sexes aged 4-5 days of postnatal life were used. As for the rats, 30 rats of Wistar variety of both sexes aged 14 to 21 days of postnatal life were used. The animals were anesthetized and had their brains removed, separated hemispheres and sections were made in the coronal plane in the occipital region where is located the visual area of rodents. Slices were maintained in artificial cerebrospinal fluid and then brought to the microscope to inject biocytin and subsequently were fixed and treated for mounting on slides and counterstained with Nissl for better viewing. Neurons found were classified as horizontal, ascending, descending and radial. The receptive field area, total and average dendritic length, total area of the cell body, dendrites number, distance from the pia mater and distribution analysis Sholl: The following dendritic measures were analyzed. Results of the most notable were the extent of dendritic branches and the size of the cell body of neurons of layer I of the guinea pig compared to rat. This suggests that in this species, a larger number of neural microcircuits can be established, and therefore greater metabolic rate justified by the size of the cell body.
Acesso aberto (Open Access)
Caracterização cromossômica e mapeamento genômico comparativo de Oecomys paricola e Oecomys auyantepui com sondas de Hylaeamys megacephalus (Cricetidae – Sigmodontinae)
(Universidade Federal do Pará, 2015-05-19) ROSA, Celina Coelho da; NAGAMACHI, Cleusa Yoshiko; http://lattes.cnpq.br/8887641213110093
The Order Rodentia represents the largest mammal order, with approximately 42% of species currently known. Rodents have 2,227 species, 468 genera and 33 families recent, the latter being raised to 50 if the extinct families are considered. Their huge variation in morphology, diversity of habitats and climates and food are the causes of this be most numerous and evolutionarily successful among mammalian orders. The Oecomys genus belongs to the subfamily Sigmodontinae (Cricetidae, Rodentia) with approximately 16 described species, distributed in tropical and subtropical forest of Central and South America. Previous cytogenetic studies suggest that Oecomys features large karyotype diversity, with the diploid number ranging from 58 to 86. In this study were analyzed by conventional cytogenetic techniques and multidirectional chromosome painting (using whole chromosome probes of Hylaeamys megacephalus) 18 specimens of Oecomys were analyzed, four were collected in the metropolitan area of Belém, Pará; two in the city of Santa Barbara, Pará; five in the region of Carajás, Pará and 7 in Calha Norte region, Pará. Specimes from Belém Environmental Park had 2n = 72 and FN = 76; specimes from Santa Barbara had 2n = 70 and FN = 74; from Carajás presented 2n = 70 and FN = 72. All this sample was identified as O. paricola. Specimens collected from the Calha Norte region had 2n = 62 and NF = 80 and were identified as O. auyantepui. The cytotypes described for O. paricola showed differences in five HME peaks, indicating 3 associations for this species. O. auyantepui showed five associations. Chromosomal differences found for O. paricola from different geographic regions suggest that these cytotypes belong to cryptic species. We suggest that these populations of O. paricola are a complex of species where the chromosomal differentiation already happened but not the morphological and molecular ones.
Acesso aberto (Open Access)
Dieta de Micoureus demerarae (Thomas) (Mammalia, Didelphidae) associada às florestas contíguas de mangue e terra firme em Bragança, Pará, Brasil
(2006-12) FERNANDES, Marcus Emanuel Barroncas; ANDRADE, Fernanda Atanaena Gonçalves de; SILVA JÚNIOR, José de Sousa e
The diet of Micoureus demerarae (Thomas, 1905) was studied in mangrove and terra firme stands by using stomachal and faecal samples. The number of captured individuals was inversely proportional to availability of fruits and insects, being Coleoptera and Hemiptera the most consumed arthropod orders and Passifloraceae and Arecaceae the most ingested fruits. Thus, either fruits variability or their high yield during the dry season seem to explain the increase of captured animals in the terra firme stands, where they originally come from. The food items suggest that this species has an omnivorous diet, independently of the seasonality or distribution of available resources.
Acesso aberto (Open Access)
Diversidade morfológica e molecular do gênero Oecomys thomas, 1906 (Rodentia: Cricetidae) na Amazônia oriental brasileira
(Universidade Federal do Pará, 2010) FLORES, Tamara Almeida; SILVA JÚNIOR, José de Sousa e; http://lattes.cnpq.br/4998536658557008; ROSSI, Rogério Vieira; http://lattes.cnpq.br/0447251112059340
The arboreal rice rats, genus Oecomys, are distributed in tropical and subtropical areas from Central and South America, with 17 currently recognized species and another two species already described in earlier studies but still unnamed. Six of these species are expected to occur in eastern Brazilian Amazon. Because defining the species limits inside Oecomys based only on morphological characters is a complicated task, many nominal taxa have already been associated to the genus, and different taxonomic arrangements have been proposed by specialists. Despite of this taxonomic instability, there is only one taxonomic review for the genus carried out 50 years ago, in which only two polytypical species were recognized. However, several recent studies based on morphological, molecular and karyotypical data have been showing that the species diversity inside Oecomys is largely underestimated, resulting in recent descriptions of new taxa or revalidation of previously synonymized species. This work aimed to assess the species diversity inside this genus in the eastern Brazilian Amazon by investigating the molecular and morphological variation in regional specimens. We employed phylogenetic analysis based on cytochrome-b in order to define clades that may represent species, and described the external and cranial morphology of these recognized species. As a result, we recognized 11 species in the eastern Amazonian forest in Brazil, of which five are already expected to occur in this area (Oecomys auyantepui, O. bicolor, O. paricola, O. rex, and O. rutilus), two are recorded for the first time in the biome Amazonia (Oecomys catherinae and O. cleberi), and the four are either new or not currently recognized species (i.e. synonyms), herein referred as Oecomys sp. A, Oecomys sp. B, Oecomys sp. C, and Oecomys sp. D. Moreover, we suggest that Oecomys bicolor is a species complex, based in the high nucleotide divergence we found (7.5 %), corroborating previous molecular studies. We observed sexual dimorphism and ontogenetic variation on cranial morphometry in the species Oecomys paricola, and for comparison purposes we treated all other species herein studied as exhibiting this kind of dimorphism. We also suggest a phylogenetic hypothesis among the species of this genus based on 653 bp of cytochrome-b. This is the most comprehensive phylogeny for Oecomys published to date, due to the great number of species included in the analysis (11 of the 16 currently recognized species plus seven probably new species), and the wide-ranging geographic area included in our sample.
Acesso aberto (Open Access)
Estudos citogenéticos em roedores do gênero oecomys (rodentia: cricetidae)
(Universidade Federal do Pará, 2011-04-29) ROSA, Celina Coelho da; NAGAMACHI, Cleusa Yoshiko; http://lattes.cnpq.br/8887641213110093
The rodents are one of the most diversified groups of living mammals and also have a large range of ecological adaptations. The rodents, because of yours population characteristics, developed as the most specious group of mammals in Neotropical forests and one of the most interesting for studies of genetic variation and evolution among vertebrates. The genus Oecomys (Sigmodontinae) comprises approximately 16 species that inhabit tropical and subtropical forests in Central and South America. Six of these species are expected to occur in eastern Brasilian Amazon. In literature, the genus Oecomys has a large karyotypic variation, where the diploid number ranges from 58 to 86. In this study specimens of Oecomys paricola Thomas, 1904 from Belém and Marajó Island, northern Brazil, were investigated using cytogenetic, molecular and morphological analyses. Three karyotypes were found, two from Belém (2n=68, FN=72 and 2n=70, FN=76) and a third from Marajó Island (2n=70, FN=72). No molecular or morphological differences were found between the individuals with differing cytotypes from Belém and Marajó Island. Specimens from the Belém City region may represent two cryptic species because two different karyotypes are present in the absence of significant differences in morphology and molecular characteristics. The Marajó Island and Belém populations represent distinct species that have been separated for some time, and are in the process of morphological and molecular differentiation as a consequence of reproductive isolation at the geographic and chromosomal levels.
Acesso aberto (Open Access)
Influência do tamanho da ninhada sobre o declínio cognitivo e a morfologia microglial da camada molecular do giro denteado em rattus novergicus
(Universidade Federal do Pará, 2012-10-11) OLIVEIRA, Marcus Augusto de; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286; DINIZ JUNIOR, José Antônio Picanço; http://lattes.cnpq.br/3850460442622655
It has been proposed that aging is associated with neuroinflammation in the central nervous system but it is not known whether microglial changes induced by aging are affected by early in life effects of litter size. On the other hand the molecular layer of dentate gyrus has been recognized as the main target of the perforant pathway, whose synaptic integrity is essential for the recognition memories of identity and spatial location. In the present report we investigated if aging cognitive decline and microglial morphological changes in the molecular layer are influenced by litter size changes early in life and aging. To assess these questions Wistar rats suckled in litters of six or 12 pups/mother were raised sedentarily in groups of 2-3 from the 21st post-natal day onwards. At four (mature adult) or 23 (aged) months of age were submitted to spatial memory and object identity recognition tests, sacrificed, perfused with aldehyde fixatives and had their brains processed for selective microglia/macrophages immunolabeling with anti-IBA-1 antibodies. A representative sample of the immunolabeled cells in the molecular layer of dentate gyrus was analyzed after three-dimensional reconstruction with Neurolucida software (Microbright Field Inc.) and morphological features of each cell were quantified by Neuroexplorer (Microbright Field Inc.). It was found that Wistar rats maintained all life in standard laboratory cages showed spatial memory deficits in both mature and aged subjects no matter the litter size. On the other hand all aged subjects independent of the litter size had their object recognition identity memory impaired. Microglial morphological analysis revealed that cell soma area and perimeter and branches volume seem to be more intensely affected by aging and that these changes are mainly associated with animals from large litters. In addition it was observed important shrinkage and thickening of the microglial branches in aged individuals in higher proportion in the group from large litters. Taken together the results suggest that spatial memory seems to be more susceptible to the aging process than object recognition and that these changes are associated with distinct effects on the soma and branching patterns of microglia of molecular layer from young and aged subjects.
Acesso aberto (Open Access)
Karyotypic analysis in species of the genus Dasyprocta (Rodentia: Dasyproctidae) found in Brazilian Amazon
(2003-03) RAMOS, Rosemar Silva Luz; VALE, William Gomes; ASSIS, Maria de Fátima Lima
A total of 30 animals of the genus Dasyprocta were cytogenetically studied. They belong to the following species: D. prymnolopha (N=20), D. leporina (N=6), D. fuliginosa (N=1) and Dasyprocta sp. (N=3) (Dasyproctidae, Hystricognathi). Cell suspensions were obtained by peripheral blood culture, besides bone marrow and spleen cells, from D. prymnolopha and D. leporina. The diploid number was 64/65 for all samples. The karyotypes showed similarity, and chromosomal polymorphism was not detected by Giemsa conventional staining and G banding. The constitutive heterochromatin distribution at the pericentromeric region of all the chromosomes was similar in all species. D. prymnolopha, D. leporina and Dasyprocta sp. presented variation in the heterochromatical block size at one of the homologues of the A18 pair. D. fuliginosa presented the heterochromatin uniformly distributed in all chromosomes. There was not variation in the NORs pattern in the species studied.
Acesso aberto (Open Access)
Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)
(2009-12) BARROS, Maria Claudene; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio; BONINO, Alfredo Ricardo Langguth
A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree was enriched with the area of occurrence and with information on the karyotype of the samples. Based on this enriched tree, and with a described methodology, hypotheses were proposed on the karyotype and area of occurrence of the ancestors of each Clade. Thus it was possible to discuss hypotheses on chromosome evolution of the group, and on dispersion events from the "area of original differentiation" of akodontines in the Andes. Chromosome evolution started with high diploid numbers (2n=52) and showed a tendency to reduction (until 2n=14 in more recent clades). Independent side-branches of the tree showed 2n reduction and in one case the 2n increased. At least four dispersion events from the Andes down to South-eastern Brazil were proposed. The results should suggest the direction of new studies on comparative karyology.
Acesso aberto (Open Access)
Parâmetros demográficos de Micoureus demerarae (Didelphidae, Marsupialia) em áreas contíguas de manguezal e terra firme, Bragança, Pará, Brasil
(2007-06) ANDRADE, Fernanda Atanaena Gonçalves de; FERNANDES, Marcus Emanuel Barroncas; BRITO, Stélio Ângelo da Costa
This study investigated some aspects of the population dynamics of Micoureus demerarae (Thomas, 1905), such as: density, recruitment, and survivorship in two contiguous ecosystems, mangal and terra firme at the Fazenda das Salinas in the northeast of the state of Pará. One transect in each system was used for fieldwork. Data collection was carried out from November 2002 to September 2003. The following population parameters were estimated: density, recruitment, and survivorship. The results defined an open population with an even distribution for individuals from mangal and a clumped one for individuals from terra firme, and the evident seasonality with higher proportion of males in the terra firme. The reproductive period was the most important parameter to the population fluctuation in the beginning of the dry season. The environmental impacts over the population dynamics parameters of M. demerarae seem to be determinant for the maintenance of these populations.
Acesso aberto (Open Access)
The effects of diazepam on the elevated T-maze are dependent on the estrous cycle of rats
(2009-12) GOUVEIA JUNIOR, Amauri; ANTUNES, Gabriela; OLIVEIRA, Caio Maximino de; CARVALHO, Silvio Morato de
In order to determine the modulation of anxiolytic and panicolytic-like effects of diazepam by the hormonal cycle of female rats, male and female rats – the latter divided per estrous cycle phase (estrus, diestrus, metaestrus and proestrus) – were tested in the elevated T-maze, a behavioral model of panic and anxiety. Diazepam (0.5, 1.0 and 2.0 mg/kg) or saline solution was injected in individual animals that were submitted to one session in the elevated T-maze 25 min after drug/saline administration. The test consisted of three avoidance trials and one escape trial, separated by a 30 s interval, during which the animals were isolated in individual cages. The avoidance trials began with the animal being placed at the end of the maze's enclosed arm. The time necessary for the animal to leave the central square was considered as the response's latency. The trials that exceeded 300 s were considered as failures. Results demonstrate a decrease in the effects of diazepam in inhibitory avoidance (anxiety) trials in females in diestrus and proestrus, but no relation of gender or estrous cycle on diazepam effects on escape trials (fear). The results support the hypothesis that down-regulation of GABAA receptors by activation of nuclear estrogen receptors and induction of PKC-mediated GABAA receptor phosphorylation by activation of surface estrogen receptors in raphe neurons underlie the modulation of diazepam sensitivity by estrogen.