Molecular characterization of SSS139, a new satellite DNA family in sibling species of the Drosophila buzzatii cluster

We characterized sequences of a novel SSS139 RsaI satellite DNA family in Drosophila gouveai and Drosophila seriema, two members of the Drosophila buzzatii cluster (D. repleta group). The sequences were AT-rich (69 percent) with a monomer unit length of about 139 bp and contained two direct subrepeats of 14 bp and 16 bp, suggesting that it might have originated by the duplication of smaller sequences. Southern and dot-blot hybridization analyses also detected SSS139 in other Drosophila buzzatii cluster species (D. koepferae, D. antonietae, D. borborema and D. serido) but not in D. buzzatii. These results agree with the marginal phylogenetic position of D. buzzatii within the D. buzzatii cluster.

Satellite DNA sites in four species of the genus Astyanax (Teleostei, Characiformes)

Cytogenetic data about satellite DNA distribution in four Astyanax species (Characidae) from the Paraitinga river, Paraíba do Sul river basin, Brazil, are presented. In order to characterize the constitutive heterochromatin, C-banding, chromomycin A3 and DAPI fluorescence staining, as well as fluorescence in situ hybridization (FISH) with the satellite DNA As-51 probe were performed. A. scabripinnis and A. parahybae presented 2n = 50 and 2n = 48 chromosomes, respectively. The heterochromatin was located in the pericentromeric and terminal regions of many chromosomes, corresponding to GC-positive regions and to the As-51 satellite DNA in terminal regions. A. intermedius and A. giton, both with 2n = 50 chromosomes, showed little heterochromatin, mostly restricted to the terminal and pericentromeric regions of a few chromosomes. No GC-positive regions, neither any correspondence between the scarce heterochromatin of these species and the As-51 satellite DNA was observed. AT-positive blocks were not detected in any of the species studied. Based on these and other available data, the hypothesis that Astyanax represents a polyphyletic group is discussed.

X chromosome centromeric alpha satellite DNA variation in Klinefelter's syndrome patients and their parents / 重庆医科大学学报

Objective:To study the variation of X chromosome centromeric Alpha Satellite DNA in Klinefelter's syndrome patients,their parents and normal individuals and to discuss the mechanism of Klinefelter's syndrome X chromosome nondisjunction.Methods:The multi-copies of a 2Kb tandem repeat unit on X chromosome of centromeric Alpha Satellite DNA were simultaneously amplified with reasonable primers by (representative sampling of multiple repetitive units,rep)PCR,and the mechanism of X chromosome aneuploidy resulted by abnormal structure of centromere was investigated.Results:1774bp,570bp and 1410bp,583bp,220 bp (three short fragments are resulted by deletion in alpha satellite DNA) were detected in Klinefelter's syndrome patients,their parents and normal karyotype controls.There were 1774bp and 1410bp DNA fragments in all of samples.The relative frequencies of 570bp and 583 bp were significantly higher in Klinefelter's syndrome patients than in normal karyotype controls,the 220bp was not found significantly different in the three groups.Conclusion:Deletion in the region of Alpha Satellite DNA is present at centromeres of all human X chromosome,while Klinefelter's syndrome patients and their parents show higher frequency than normal individuals.These results imply that analysis of deletion on X-specific ?satellite of the parents during the pre-pregnancy and pregnancy plays a important role either in estimating the risk of repruducing Klinefelter's syndrome or in providing the guideline for prenatal chromosome diagnosis of villus and amniotic fluid.