Biomedical subjects

J Pasantes

Publications and source records attributed to J Pasantes.

7 recordsLinked to original sources

PubMed2000

Familial mosaicism of del(Y) and inv del(Y).

Molecular cytogenetic investigation of a male proband showing oligozoospermia (OAT I-II degrees ) has led to the detection of a Y-chromosome mosaicism. This mosaicism consists of a deleted Y chromosome with deletion of most of the long-arm heterochromatin, including the PAR2, del(Y), and a Y chromosome, which, in addition to that deletion, shows a paracentric long-arm inversion, inv del(Y), with breakpoints in the DAZ gene cluster in deletion interval 6 and within the remainder of the long-arm heterochromatin of the Y. The Y mosaicism is not confined to the sterile proband but is also detected in both his father and his fertile brother. Interestingly, the percentage of inv del(Y) is highest (80%) in the proband showing oligozoospermia.

Adult↗

PubMed1998

Concerted evolution of members of the multisequence family chAB4 located on various nonhomologous chromosomes.

During the last years it became obvious that a lot of families of long-range repetitive DNA elements are located within the genomes of mammals. The principles underlying the evolution of such families, therefore, may have a greater impact than anticipated on the evolution of the mammalian genome as a whole. One of these families, called chAB4, is represented with about 50 copies within the human and the chimpanzee genomes and with only a few copies in the genomes of gorilla, orang-utan, and gibbon. Members of chAB4 are located on 10 different human chromosomes. FISH of chAB4-specific probes to chromosome preparations of the great apes showed that chAB4 is located, with only one exception, at orthologous places in the human and the chimpanzee genome. About half the copies in the human genome belong to two species-specific subfamilies that evolved after the divergence of the human and the chimpanzee lineages. The analysis of chAB4-specific PCR-products derived from DNA of rodent/human cell hybrids showed that members of the two human-specific subfamilies can be found on 9 of the 10 chAB4-carrying chromosomes. Taken together, these results demonstrate that the members of DNA sequence families can evolve as a unit despite their location at multiple sites on different chromosomes. The concerted evolution of the family members is a result of frequent exchanges of DNA sequences between copies located on different chromosomes. Interchromosomal exchanges apparently take place without greater alterations in chromosome structure.

Animals↗

PubMed1997

Comparative mapping of Xp22 genes in hominoids--evolutionary linear instability of their Y homologues.

Several genes located within or proximal to the human PAR in Xp22 have homologues on the Y chromosome and escape, or partly escape, inactivation. To study the evolution of Xp22 genes and their Y homologues, we applied multicolour fluorescence in situ hybridization (FISH) to comparatively map DNA probes for the genes ANT3, XG, ARSD, ARSE (CDPX), PRK, STS, KAL and AMEL to prometaphase chromosomes of the human species and hominoid apes. We demonstrate that the genes residing proximal to the PAR have a highly conserved order on the higher primate X chromosomes but show considerable rearrangements on the Y chromosomes of hominoids. These rearrangements cannot be traced back to a simple model involving only a single or a few evolutionary events. The linear instability of the Y chromosomes gives some insight into the evolutionary isolation of large parts of the Y chromosomes and thus might reflect the isolated evolutionary history of the primate species over millions of years.

Animals↗

PubMed1994

Autosomal sex reversal and campomelic dysplasia are caused by mutations in and around the SRY-related gene SOX9.

A human autosomal XY sex reversal locus, SRA1, associated with the skeletal malformation syndrome campomelic dysplasia (CMPD1), has been placed at distal 17q. The SOX9 gene, a positional candidate from the chromosomal location and expression pattern reported for mouse Sox9, was isolated and characterized. SOX9 encodes a putative transcription factor structurally related to the testis-determining factor SRY and is expressed in many adult tissues, and in fetal testis and skeletal tissue. Inactivating mutations on one SOX9 allele identified in nontranslocation CMPD1-SRA1 cases point to haploinsufficiency for SOX9 as the cause for both campomelic dysplasia and autosomal XY sex reversal. The 17q breakpoints in three CMPD1 translocation cases map 50 kb or more from SOX9.

Amino Acid Sequence↗

PubMed1989

Denaturing effect of acridine orange and adriamycin.

Acridine orange and adriamycin have a very low denaturing effect on DNA isolated from Chinese hamster cells but strongly increase heat-induced denaturation. When these intercalating agents are added to the growth media they modify the sensitivity to heat denaturation of DNA extracted from treated cultures when compared with untreated cultures. This effect correlates with a considerable increase in the disruption of chromosomal ultrastructure.

Acridine Orange↗

PubMed1988

Changes in metaphasic chromosomal ultrastructure caused by denaturing treatments.

Denaturation and posterior renaturation of metaphase chromosomes after different treatments were tested by acridine orange staining. A relationship between conservation of ultrastructure and the capacity to renature was discovered. Amyl acetate, commonly used in electron microscopy to fix chromosomes, avoids the action of denaturing agents and this effect is not reversed by chromosome rehydration.

Animals↗

PubMed1987

Morphological parameter variations between sister chromatids by electron microscopy.

Five morphological parameters of sister chromatids, viz radius, length, centromeric index, volume and centromere width, were studied by electron microscopy, from 140 human number 1 chromosomes, and 122 human number 2 chromosomes. The degree of variation obtained ranged from 0.277 +/- 0.003% and 0.286 +/- 0.005% for the centromeric index of chromosomes 1 and 2, respectively, to 9.835 +/- 0.933% and 13.472 +/- 1.461% for centromere width.

Cells, Cultured↗