12 research outputs found
Isolation of subtelomeric DNA sequences labelling sheep and goat chromosome ends
Two techniques that make it possible to isolate telomere DNA are presented, using sheep as an example. The first technique is based upon the screening of a sheep BAC library with PCR amplified DNA segments preserved from high-power laser beam irradiation. Twenty-three BACs hybridising to 13 subtelomeric regions in sheep and goats were obtained (out of 27 in the sheep complement), of which 13 recognised more than one region, telomeric or not. Twenty-three microsatellites were isolated from these BACs and 22 were genetically mapped on the sheep international genetic map, always consistently with the cytogenetical localisation in 17 cases out of 22. These results are discussed. The second technique is based upon the selective cloning of subtelomeric enriched DNA. Preliminary results were obtained by this approach
Role of the Epigenetic Regulator HP1γ in the Control of Embryonic Stem Cell Properties
The unique properties of embryonic stem cells (ESC) rely on long-lasting self-renewal and their ability to switch in all adult cell type programs. Recent advances have shown that regulations at the chromatin level sustain both ESC properties along with transcription factors. We have focused our interest on the epigenetic modulator HP1γ (Heterochromatin Protein 1, isoform γ) that binds histones H3 methylated at lysine 9 (meH3K9) and is highly plastic in its distribution and association with the transcriptional regulation of specific genes during cell fate transitions. These characteristics of HP1γ make it a good candidate to sustain the ESC flexibility required for rapid program changes during differentiation. Using RNA interference, we describe the functional role of HP1γ in mouse ESC. The analysis of HP1γ deprived cells in proliferative and in various differentiating conditions was performed combining functional assays with molecular approaches (RT-qPCR, microarray). We show that HP1γ deprivation slows down the cell cycle of ESC and decreases their resistance to differentiating conditions, rendering the cells poised to differentiate. In addition, HP1γ depletion hampers the differentiation to the endoderm as compared with the differentiation to the neurectoderm or the mesoderm. Altogether, our results reveal the role of HP1γ in ESC self-renewal and in the balance between the pluripotent and the differentiation programs
Direct hybridization of sorted human chromosomes: localization of the Y chromosome on the flow karyotype.
Isolation of subtelomeric DNA sequences labelling sheep and goat chromosome ends
Two techniques that make it possible to isolate telomere DNA are presented,
using sheep as an example. The first technique is based upon the screening
of a sheep BAC library with PCR amplified DNA segments preserved from
high-power laser beam irradiation. Twenty-three BACs hybridising to
13 subtelomeric regions in sheep and goats were obtained (out of 27
in the sheep complement), of which 13 recognised more than one region,
telomeric or not. Twenty-three microsatellites were isolated from these
BACs and 22 were genetically mapped on the sheep international genetic map,
always consistently with the cytogenetical localisation in 17 cases out
of 22. These results are discussed. The second technique is based upon the
selective cloning of subtelomeric enriched DNA. Preliminary results were
obtained by this approach.Isolement de séquences d'ADN subtélomériques chez les ruminants.
Deux techniques permettant d'isoler l'ADN télomérique sont présentées,
le mouton servant d'exemple. La première technique est basée sur le criblage
d'une banque de BACs ovins avec des segments d'ADN amplifiés par PCR préservés
de l'irradiation par un laser à forte puissance. Vingt trois BACs s'hybridant
à 13 régions sub-télomériques (parmi les 27 du génome ovin) ont été obtenus,
dont treize reconnaissent plus qu'une région unique, télomérique ou non.
Vingt-trois microsatellites ont été isolés à partir des BACs et 22
cartographiés génétiquement sur la carte ovine internationale, de façon
cohérente avec la localisation cytogénétique dans 17 cas sur 22. Ces résultats
sont discutés. La seconde technique est basée sur le clonage sélectif d'ADN
enrichi en régions sub-télomériques. Des résultats préliminaires ont été
obtenus par cette approche