Abstract: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 convention… Show more
“…There is no cytogenetic data known for three species (Table 1). The diploid number in the Family varied from 62 to 65, and in the genus Dasyprocta, from 64 to 65, due to the presence of B chromosomes in four species (Ramos et al 2003). …”
Rodents constitute one of the most diversified mammalian orders. Due to the morphological similarity in many of the groups, their taxonomy is controversial. Karyotype information proved to be an important tool for distinguishing some species because some of them are species-specific. Additionally, rodents can be an excellent model for chromosome evolution studies since many rearrangements have been described in this group.This work brings a review of cytogenetic data of Brazilian rodents, with information about diploid and fundamental numbers, polymorphisms, and geographical distribution. We point out that, even with the recent efforts on cytogenetic studies in this group, many species lack karyotypic data. Moreover, we describe for the first time the karyotype of Carterodon
sulcidens (Lund, 1838) (Family Echimyidae), a new fundamental number for an undescribed species of Neacomys Thomas, 1900 (Family Cricetidae, Subfamily Sigmodontinae), and illustrate the karyotype of a Brazilian specimen of Mus
musculus Linnaeus, 1758 (Family Muridae). This review compiles the cytogenetic data on Brazilian rodents reported in the last three decades, after the last revision published in 1984, including synonyms, chromosomal variations, and geographic distribution. Additionally, it also reinforces that Brazilian biodiversity is still poorly known, considering the new data reported here.
“…There is no cytogenetic data known for three species (Table 1). The diploid number in the Family varied from 62 to 65, and in the genus Dasyprocta, from 64 to 65, due to the presence of B chromosomes in four species (Ramos et al 2003). …”
Rodents constitute one of the most diversified mammalian orders. Due to the morphological similarity in many of the groups, their taxonomy is controversial. Karyotype information proved to be an important tool for distinguishing some species because some of them are species-specific. Additionally, rodents can be an excellent model for chromosome evolution studies since many rearrangements have been described in this group.This work brings a review of cytogenetic data of Brazilian rodents, with information about diploid and fundamental numbers, polymorphisms, and geographical distribution. We point out that, even with the recent efforts on cytogenetic studies in this group, many species lack karyotypic data. Moreover, we describe for the first time the karyotype of Carterodon
sulcidens (Lund, 1838) (Family Echimyidae), a new fundamental number for an undescribed species of Neacomys Thomas, 1900 (Family Cricetidae, Subfamily Sigmodontinae), and illustrate the karyotype of a Brazilian specimen of Mus
musculus Linnaeus, 1758 (Family Muridae). This review compiles the cytogenetic data on Brazilian rodents reported in the last three decades, after the last revision published in 1984, including synonyms, chromosomal variations, and geographic distribution. Additionally, it also reinforces that Brazilian biodiversity is still poorly known, considering the new data reported here.
The study of B chromosomes (Bs) started more than a century ago, while their presence in mammals dates since 1965. As the past two decades have seen huge progress in application of molecular techniques, we decided to throw a glance on new data on Bs in mammals and to review them. We listed 85 mammals with Bs that make 1.94% of karyotypically studied species. Contrary to general view, a typical B chromosome in mammals appears both as sub- or metacentric that is the same size as small chromosomes of standard complement. Both karyotypically stable and unstable species possess Bs. The presence of Bs in certain species influences the cell division, the degree of recombination, the development, a number of quantitative characteristics, the host-parasite interactions and their behaviour. There is at least some data on molecular structure of Bs recorded in nearly a quarter of species. Nevertheless, a more detailed molecular composition of Bs presently known for six mammalian species, confirms the presence of protein coding genes, and the transcriptional activity for some of them. Therefore, the idea that Bs are inert is outdated, but the role of Bs is yet to be determined. The maintenance of Bs is obviously not the same for all species, so the current models must be adapted while bearing in mind that Bs are not inactive as it was once thought.
“…Cytogenetic studies are essential because each species is characterized by a typical karyotype, which may differ from others with respect to form, size, and number of chromosomes (Lima, 2000). By cytogenetic analysis of 30 animals of the genus Dasyprocta (D. prymnolopha, D. leporina, and D. fuliginosa), Ramos et al (2003) identified that the individuals presented two cellular lineages, with 2n = 64 and 2n = 65 chromosomes. The karyotypes showed similarity, and chromosomal polymorphism was not detected by Giemsa conventional staining and G banding.…”
Section: General Characteristics Of Male and Female Agoutimentioning
confidence: 99%
“…This variation was observed with a frequency of approximately 70% in cells with 2n = 64 and 30% in cells with 2n = 65. There was no variation in the pattern of nucleolus organizer regions (NORs) in the species studied, which was used to verify chromosomal polymorphism (Ramos et al, 2003).…”
Section: General Characteristics Of Male and Female Agoutimentioning
Dasyprocta spp. (agouti) include wild rodents with highlighted ecological and economic importance, and are considered experimental models for endangered hystricognath rodents. Of late, development of techniques to conserve their genetic material as well as the formation of biobanks is increasing. In this context, this review describes the main advances in the knowledge of the reproductive morphophysiological specificities of agouti as well as the development and improvement of assisted reproductive techniques aimed at conservation, multiplication, and exploitation of their reproductive potential under captivity.
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