摘要:

The metaphase chromosomes of five wild species of the sectionVignaof the genusVigna, namelyV. ambacensis, V. heterophylla, V. racemosa, V. marina, andV. graciliswere analysed in order to define the reacting properties to differential staining methods and chromosomal distribution of the different fractions of their heterochromatin, using C-banding and fluorochrome staining as discriminating techniques. Based on these characters it was possible to cluster the above species into three homogeneous groups:V. ambacensisandV. heterophyllabelong to the first cluster,V. racemosais the only member of the second group, andV. marinaandV. gracilisform the third set. Species clustered into the first group show heterochromatin chromosomal distribution and reacting properties more similar to those of the cultivated speciesV. unguiculatathan the other two sets. These findings are compared to those of earlier studies on related species.

ISSN:0008-7114    

DOI:10.1080/00087114.1996.10797375

出版商:Taylor & Francis    

年代:1996

数据来源: Taylor

摘要:

Oryzomysis the genus of South American cricetine rodents with the greatest number of species. More than 50 nominal forms have been assigned to the genus, but the taxonomical situation of most of these still confusing.Oryzomysalso shows a great chromosomic differentiation and it karyotypes have been used as a diagnostic character for its species. With the aim of determinating the taxonomical frontiers between the species of themacconnelli-capitogroup, the banding karyotypes of two morphologically similar species of this group:O. talamancaeandO. capitowere studied. The karyotype ofOryzomys talamancaeis very different from that of the other species of this genus, because it has few elements (34) and they are all biarmed. On the other hand, the karyotype ofO. capito, constituted by 54 chromosomes, mostly acrocentrics, is rather ordinary among the oryzomyine. G-banding was performed with tripsin treatment, and C-bands by denaturation-renaturation. The comparison of the G-banding patterns allowed us to detect at least three chromosomic arms shared by both karyotypes. The C-banding pattern ofO. talamancaeis very peculiar because the heterochromatin was found only on the centromeres of two autosomic pairs and on the X chromosome. These results suggest that chromosomic differentiation between the two species has occurred via Robertsonian fusions.

ISSN:0008-7114    

DOI:10.1080/00087114.1996.10797376

出版商:Taylor & Francis    

年代:1996

数据来源: Taylor

摘要:

The chromosomes of the South American rodentCalomys musculinushave been analyzed by standard Giemsa C-banding, chromomycin A3, distamycin A and DAPI fluorochrome staining and “in situ” digestion with the restriction endonucleases Alul, HaeIII and HindIII. Constitutive heterochromatin is restricted to the centric regions, and fluoresces after either chromomycin A3 or DAPI treatments, indicating the co-existence of AT and GC-rich sequences in these regions. The restriction enzymes assayed induce diffuse, overlapping patterns of centric and interstitial bands in the chromosomes of this species. Our results agree with other authors' biochemical analyses that indicate the existence of moderately to highly repetitive DNA sequences inC. musculinusthat do not appear as a satellite in neutral CsCI DNA gradients, as well as a great abundance of the cleavage sites of these restriction enzymes in the genome of this rodent.

ISSN:0008-7114    

DOI:10.1080/00087114.1996.10797377

出版商:Taylor & Francis    

年代:1996

数据来源: Taylor

摘要:

Cytogenetic studies conduced on a sample of 19 specimens of rainbow trout(Oncorhyncus mykiss)showed that 6 presented two chromosomes with a single subterminal AgNOR on the short arms and 13 presented one chromosome with a single subterminal Ag-NOR and a second chromosome with two small subterminal Ag-NORs. Synaptonemal complex studies showed the presence of a pairing failure involving the two lateral elements (LEs) of the NOR-bearing chromosomes only in those specimens with two different NOR-bearing chromosomes, suggesting that the chromosomes with two Ag-NORs originated from a paracentric inversion involving a terminal segment of the original NOR-bearing chromosome. A comparative analysis between three normal and three heterozygous fishes suggest that in the latter group the LEs of the NOR-bearing chromosomes initiate the synaptic process in a more delayed manner, the synapsis develops more quickly, and the nucleolus stays associated with chromosomes for a longer time.

ISSN:0008-7114    

DOI:10.1080/00087114.1996.10797378

出版商:Taylor & Francis    

年代:1996

数据来源: Taylor

摘要:

We have analysed different populations of European mussels belonging to genusMytilusin order to clarify the karyotype complements of these three species (M. edulis, M. galloprovincialisandM. trossulus). We have employed different cytogenetic techniques (C-banding, fluorochrome staining and Ag-NOR staining) and we have carried out chromosome measurements by using image analysis. Results obtained allow us to confirm the diploid number of these species and to detect different karyotype composition. Furthermore, we describe cytogenetical differences between larval chromosomes and gill tissue chromosomes.

ISSN:0008-7114    

DOI:10.1080/00087114.1996.10797379

出版商:Taylor & Francis    

年代:1996

数据来源: Taylor