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N Lévy

Publications and source records attributed to N Lévy.

24 records · Page 2Linked to original sources
PubMed1996

Localization of ribosomal genes in human spermatogonia by fluorescent in situ hybridization and confocal microscopy.

The distribution of ribosomal RNA genes in nucleoli is still a matter of controversy. We have investigated the nucleolus of human type A spermatogonia, which displays a single, large fibrillar center. Silver-staining was used to localize the fibrillar center by light microscopy. Fluorescent in situ hybridization was performed on the same cell, using a 5.8-kb probe specific for a transcribed region of the ribosomal genes. The fluorescent area exactly corresponded to the silver-stained area. The three-dimensional distribution of rDNA was studied in horizontal and orthogonal sections using a confocal laser scanning microscope. The presence of the fluorescent signal throughout the whole silver-stained structure demonstrated that the fibrillar center, and at least a part of the dense fibrillar component, contained most of the rDNA.

Cell Nucleolus↗
PubMed1993

Isolation of cosmids and fetal brain cDNAs from the proximal long arm of human chromosome 22.

The proximal portion of human chromosome 22q appears to carry genes implicated in the pathogenesis of various developmental disorders, including the cat eye syndrome (CES) and the DiGeorge syndrome (DGS). A cosmid library was prepared from a radiation hybrid selected for its content in chromosome 22 fragments. A large fraction of cosmids containing human DNA were found to derive from the juxtacentromeric region of chromosome 22, as shown by fluorescence in situ hybridization (FISH) performed using individual cosmids or cosmid pools as probes. Finer mapping was obtained for individual cosmids by hybridization to a somatic cell hybrid mapping panel which splits the long arm of the chromosome into 14 bins numbered 1 to 14 from the centromere to the telomere. Of the 10 cosmids mapped, eight belonged to group 1, the other two to group 14, in agreement with FISH data. Rare endonuclease sites and fragments conserved between species were searched in single cosmids, resulting in the selection of seven cosmid fragments which were used to screen a human fetal brain cDNA library. Three cDNAs were identified, encoded from two chromosome 22 genes which appeared to be novel, as determined from partial end sequence and comparison with the database entries. Fine localization of the 30.9 cDNA indicated that the corresponding gene was located in a segment of proximal 22q overlapping with the critical DGS region.

Animals↗
PubMed1993

Localization of 15 cosmids on human chromosome 22 by fluorescence in situ hybridization.

Fluorescence in situ hybridization has been used in a cytogenetic analysis to map 15 cosmids on human chromosome 22. Thirteen cosmids were localized on the long arm of chromosome 22 (22q) while two other probes displayed a hybridization signal on 22p and the short arm of the acrocentric chromosomes of groups D and G. The regional assignment of these new chromosome markers will improve the mapping of chromosome 22; they can be used to detect numerical and structural aberrations of this chromosome involved in numerous pathologies.

Chromosome Mapping↗