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C Bouniol

Publications and source records attributed to C Bouniol.

10 recordsLinked to original sources
PubMed1996

Conditions favoring RNA polymerase I transcription in permeabilized cells.

RNA synthesis can be detected in nuclei using modified RNA precursors (Br-UTP) introduced in permeabilized cells. Surprisingly, RNA pol I transcripts are detected only after inhibition of RNA pol II or salt enhancement of RNA pol I activity. By modifying a previously reported protocol, we found that RNA pol I transcripts can be detected selectively or simultaneously with RNA pol II transcripts without any drug treatment. Removing glycerol from the permeabilization and transcription buffers and improving the permeabilization using Triton X-100 revealed RNA pol I transcription in two cell lines (mammalian and Xenopus) and in isolated mouse oocytes. The transcripts were most probably rRNA because they were detected in the nucleoli, digested by RNase, sensitive to actinomycin D, and resistant to alpha-amanitin. We found by microinjection of the Br-UTP precursors in living cells that low ionic strength allows the detection of RNA pol I transcription. Electron microscopy of mouse oocytes showed that the "looseness" of the nucleolar organization is associated with the detection of the RNA pol I transcription; this detection does not necessarily need nucleolar disorganization. The data obtained with both permeabilized cells and microinjections of RNA precursors in the absence of glycerol support the hypothesis that the degree of hydration of the cell plays a role in RNA pol I transcription.

Animals↗
PubMed1995

Endogenous transcription occurs at the 1-cell stage in the mouse embryo.

In most animal species, the earliest stages of embryogenesis are regulated by maternally inherited components, at least until the activation of the zygotic genome. Although the first proteins derived from the activation of the embryonic genome have been detected long ago at the 2-cell stage in the mouse, the exact timing of transcriptional activity resumption after fertilization is still a matter of debate. Any new information about this critical event is relevant to the practice of transgenesis and cloning of embryos as well as to the general understanding of the regulation of nuclear processes following fertilization. Using a new fluorescent method allowing the detection of in vivo RNA synthesis, we show that endogenous transcription by RNA polymerase II takes place unambiguously as early as at the late 1-cell stage. Furthermore, we demonstrate that transcription is first initiated in the paternal pronucleus.

Animals↗
PubMed1994

Biochemical and genetic analysis of variant C of caprine alpha s2-casein (Capra hircus).

Two alleles, A and B, were previously described at the goat alpha s2-casein locus. Isoelectric focusing allowed us to subdivide the former one in two new alleles, called A and C. Although alpha s2-casein C cannot actually be distinguished from its A counterpart by starch or polyacrylamide gel electrophoresis, it differs from the previous allele by a single substitution Lys (A)/Ile (C) at position 167, which was confirmed at the nucleotide level. The frequencies of the three alpha s2-casein alleles A, B and C were estimated to be 0.85, 0.04 and 0.11 in the French dairy breeds 'Alpine' and 'Saanen'.

Alleles↗
PubMed1993

Bovine alpha s2-casein D is generated by exon VIII skipping.

Bovine alpha s2-casein D (CasD) differs from the common type A by the deletion of a stretch of 9 amino acids (aa) starting at a position not precisely known, either at aa 50, 51, or 52. The sequence of cloned PCR-amplified genomic DNA from three homozygous cows, two unrelated females carrying the CasD allele and one carrying the CasA allele, did not reveal any deletion and showed two identical nucleotide (nt) substitutions in the 1.7-kb region of both CasD alleles encompassing codons 43-75 in the cDNA encoding alpha s2-CasA. This strongly suggests that the deleted bovine alpha s2-CasD arises from skipping the 27-nt exon, now identified as exon VIII, which encodes aa 51-59 of alpha s2-CasA. The G-->T transversion (allele A-->D) affecting the last nt of exon VIII, i.e., the 5' consensus splicing site, might be responsible for the altered splicing of the primary transcript of alpha s2-CasD.

Alleles↗
PubMed1993

Localization of the alpha-S2-casein gene (CASAS2) to the homoeologous cattle, sheep, and goat chromosomes 4 by in situ hybridization.

The alpha-S2-casein gene (CASAS2) has been mapped to the homoeologous cattle, sheep, and goat chromosomes 4 and to the long arm of a bovine chromosome translocation, t(4;8), using nonradioactive in situ hybridization and simultaneous fluorescent R-banding. The t(4;8) has been characterized by GTG-, GBG-, and RBG-banding and by silver staining of nucleolus organizer regions. These results confirm the previous (ISCNDA, 1989) localization of the casein gene group to chromosome 4 of cattle, sheep, and goats. We propose that the discrepancy between our results and earlier assignments of the casein gene group to chromosome 6 of cattle and sheep can be explained by the fact that the chromosome identified as No. 6 in the Reading Conference (1976) report was renamed chromosome 4 in the ISCNDA (1989) standardized karyotype of both species.

Animals↗
PubMed1991

Multiple mRNA species code for two non-allelic forms of ovine alpha s2-casein.

The two non-allelic forms of alpha s2-casein, occurring in ovine milk, differ by an internal deletion of nine amino acid residues, including both cysteine residues at positions 34 and 42 in the mature chain. Sequencing of several alpha s2-casein cDNA, isolated from the mammary cDNA library of a single lactating ewe, showed three new types which differed from that previously studied. In addition to the expected deletion of codons +34 to +42 affecting 30-40% of mRNA, another structural difference involving an internal stretch of 44 nucleotides in the 5' untranslated region, was found. S1-nuclease protection assays confirmed the existence of several types of the relevant mRNA and sequencing of in-vitro-amplified genomic DNA demonstrated the presence of the 44-nucleotide stretch in the alpha s2-casein transcriptional unit, thus ruling out the possibility of a cloning artefact. The different alpha s2-casein mRNA, four in terms of deletion and two in terms of nucleotide substitutions for a given ewe, can be readily explained by partial exon skipping and allelic differences, respectively. This assumption is well supported by the following observations: 5' and 3' ends of both deleted DNA fragments are similar to those of exons; sequences neighbouring the 44-nucleotide stretch of the genomic DNA perfectly match consensus sequences described for 3' and 5' ends of introns; the rather simple patterns observed on Southern blots of different enzymatic digests of genomic DNA strongly suggest the occurrence of only 1 copy alpha s2-casein gene/haploid genome. During the course of evolution, the alpha s2-casein-encoding gene has undergone many mutations and some of them might have occurred in regions corresponding to consensus splicing regions of the pre-mRNA. Thus, complete skipping of some exons might be responsible for the shorter sizes of rat and mouse alpha s2-casein mRNA. If so, the overall organization of the alpha s2-casein gene in the different species might be more similar than expected from structural comparisons of the cognate mRNA or caseins.

Amino Acid Sequence↗
PubMed1990

[Place of implantology in the treatment plan: apropos of some clinical situations].

The advent of osseointegrated implants has considerably influenced the treatment of the edentulism. The Brånemark's protocol allows a high enough degree of predictability for a wide variety of clinical applications. A selection of the most typical indications attempts to focus on the benefit of implant supported prosthesis, regarding the conventional prosthetic treatment. The relative indications concern single-tooth replacement and Kennedy class III situations where classical tooth supported bridge is not easily feasible. The resort to osseointegration treatment enhances the possibilities of prosthetic rehabilitation in unfavorable conditions. The greater part of the indications is represented by Kennedy class I and class II situations. Clinical examples selected show the different combinations related to the fixtures position in the maxilla where bone availability is reduced. When just one fixture can be installed, connection with adjacent tooth must be carefully indicated. With two fixtures, a bridge must be designed with a posterior cantilever. But the opposite dentition can also dictate a fixture installation in the posterior region for a good occlusal stabilization: a specific modality of fixture installation in the pterygoid region has provided a seductive alternative. The last part concerns the prosthetic rehabilitation of advanced cases involving evolutive periodontal disease. The current trends determine a flexible approach with strategic extractions and progressive fixtures installation during stabilized periods of the disease activity. This management of the treatment planning reduces the psychogenic stress related to the complete edentulism and allows a easier transition from partial implant supported-prosthesis to fully bone anchored-prosthesis.

Dental Implantation, Endosseous↗