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Biomedical subjects

C Aleixandre

Publications and source records attributed to C Aleixandre.

5 recordsLinked to original sources
PubMed1991

Inheritance of ribosomal gene activity and level of DNA methylation of individual gene clusters in a three generation family.

Ribosomal gene activity and levels of DNA methylation were investigated by cytochemical and immunological methods in the nucleolar organizer regions (NORs) of individually recognised acrocentric chromosomes. Mendelian inheritance of ribosomal gene activity in a three generation family was demonstrated, together with consistent behaviour of individual gene clusters in different carriers, even when environmental conditions were changed. For most chromosomes, an inverse relationship between gene activity and the level of DNA methylation was observed. Exceptions were the two chromosomes 15 and chromosomes 13cp and 22p, all being strongly chromomycin-A3-positive in their short arms. These chromosomes bound to anti-5-MeC antibodies with differential frequencies in the different carriers. The possibility of involvement of repetitive GC-rich DNA in this behaviour is discussed.

Azacitidine↗
PubMed1988

Relationship between the number and function of human ribosomal genes.

The relative number of ribosomal RNA genes of the acrocentric chromosomes in one individual was measured by counting grains after in situ hybridization of 3H-labeled human 18S rDNA to fixed metaphase chromosomes. The relative amount of ribosomal RNA gene activity of each of the same chromosomes was estimated by determining the frequency with which the chromosome's nucleolus organizer region (NOR) was silver stained, the size of the silver-stained region, and how often the chromosome was found in satellite association. Results were similar in phytohemagglutinin-stimulated T-lymphocytes, Epstein-Barr virus transformed lymphoblasts, and fibroblasts. One chromosome 21 had few gene copies and low activity. One chromosome 22 had many gene copies but low activity. Both chromosomes 14 had few gene copies but high activity. The level of expression that can be achieved by rRNA gene clusters can, therefore, be determined by factors other than the number of gene copies.

B-Lymphocytes↗
PubMed1987

p82H identifies sequences at every human centromere.

A cloned alphoid sequence, p82H, hybridizes in situ to the centromere of every human chromosome. After washing under stringent conditions, no more than 8% of the grains are located on any specific chromosome. p82H thus differs from other centromeric sequences which are reported to be chromosome specific, because it detects sequences that are conserved among the chromosomes. Two experimental approaches show that the p82H sequences are closely associated with the centromere. First, p82H remains with the relocated centromeres in an inv(19) and an inv(6) chromosome. Second, p82H hybridizes at the centromere but not to the centromeric heterochromatin of chromosomes 1, 9 and 16 that have elongated 1qh, 9qh and 16qh regions produced by short growth in 5-azacytidine. The only noncentromeric site of hybridization is at the distal end of the 9qh region.

Base Sequence↗