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C Bélanger

Publications and source records attributed to C Bélanger.

At least 19 recordsLinked to original sources
PubMed1999

Procedure to protect confidentiality of familial data in community genetics and genomic research.

The collection of familial data is an essential step for community genetics programs or genetic research. Ethical issues concerning privacy and confidentiality present a major challenge in such programs. In order to keep familial data confidential, we have developed a family-based numerical coding procedure which allows the use of confidential data and the determination of familial relationships without risk of disclosure. This procedure is composed of two parts: the physical separation of identifying information and individual data; and the use of a code containing all the information required to build family trees. This procedure has been used in Eastern Quebec since 1995, mainly for screening, genetic counseling, research on familial dyslipidemias, public health intervention, and research projects on the genetics of complex traits, such as arterial hypertension and coronary artery disease.

Abstracting and Indexing↗
PubMed1997

Variable efficiency of a Ti plasmid-encoded VirA protein in different agrobacterial hosts.

The transconjugant CB100, harboring the Ti plasmid from the Agrobacterium tumefaciens biovar 2 strain D10B/87 in the chromosomal background of the biovar 1 strain C58, was defective in vir gene induction. This defect was corrected in the presence of virA from pTiA6. Based on this complementation result and an analysis of the induction requirements of the transconjugant CB100 and its parent strains, it was hypothesized that the defective vir gene induction in CB100 was related to a dysfunctional interaction between the pTi-encoded D10B/87 VirA and the chromosome-encoded C58 ChvE. To verify this hypothesis, D10B/87 and C58 virA were compared, and conclusions from this first set of analyses were then corroborated by comparing D10B/87 and C58 chvE. Whereas only a few nucleotide differences were identified in the promoters and 5' ends of the coding regions of D10B/87 and C58 virA, analysis of hybrid virA genes showed that these differences collectively accounted for the poor vir gene induction of strain CB100. In contrast with the sequence similarity of the VirA proteins, extensive divergence was seen between the chromosome-encoded D10B/87 and C58 ChvE. Although D10B/87 chvE introduced in trans had little effect on vir gene induction of CB100, it enhanced the induction response of a strain CB100 derivative in which the chromosomal C58 chvE had been inactivated by marker exchange. These results suggest that chromosomal backgrounds provided by different strains of A. tumefaciens are not equivalent for VirA function. Following conjugative transfer of certain Ti plasmids to a new agrobacterial host, evolution of the newly introduced virA, or coevolution of chvE and virA, may lead to optimization of ChvE-VirA interaction and vir gene induction levels.

Agrobacterium tumefaciens↗
PubMed1996

Cardiovascular, neuroendocrine, and monoaminergic responses to psychological stressors: possible differences between remitted panic disorder patients and healthy controls.

Both clinical symptomatology and stress research suggest that panic attacks might be partially attributable to exaggerated psychophysiological responses to environmental stressors. In the present study, we aimed to explicitly test this idea by measuring the physiological responses to a mild psychological stressor in both healthy controls (n = 8) and fully remitted, medication-free panic disorder patients (n = 8). One hour before the stressor, former patients, compared to healthy controls, exhibited higher diastolic blood pressure. From a blood sample taken 30 min before the stressor, patients, compared to controls, had lower paroxetine platelet binding site densities. During the stressor, patients, compared to controls, had greater increases in plasma levels of cortisol. These preliminary findings suggest that remitted panic disorder patients might have disturbed physiological responses to mild psychological stressors. These disturbances might be related to the development of future episodes.

Adult↗
PubMed1996

Generation of an integrated transcription map of the BRCA2 region on chromosome 13q12-q13.

An integrated approach involving physical mapping, identification of transcribed sequences, and computational analysis of genomic sequence was used to generate a detailed transcription map of the 1. 0-Mb region containing the breast cancer susceptibility locus BRCA2 on chromosome 13q12-q13. This region is included in the genetic interval bounded by D13S1444 and D13S310. Retrieved sequences from exon amplification or hybrid selection procedures were grouped into physical intervals and subsequently grouped into transcription units by clone overlap. Overlap was established by direct hybridization, cDNA library screening, PCR cDNA linking (island hopping), and/or sequence alignment. Extensive genomic sequencing was performed in an effort to understand transcription unit organization. In total, approximately 500 kb of genomic sequence was completed. The transcription units were further characterized by hybridization to RNA from a series of human tissues. Evidence for seven genes, two putative pseudogenes, and nine additional putative transcription units was obtained. One of the transcription units was recently identified as BRCA2 but all others are novel genes of unknown function as only limited alignment to sequences in public databases was observed. One large gene with a transcript size of 10.7 kb showed significant similarity to a gene predicted by the Caenorhabditis elegans genome and the Saccharomyces cerevisiae genome sequencing efforts, while another contained a motif sequence similar to the human 2',3' cyclic nucleotide 3' phosphodiesterase gene. Several retrieved transcribed sequences were not aligned into transcription units because no corresponding cDNAs were obtained when screening libraries or because of a lack of definitive evidence for splicing signals or putative coding sequence based on computational analysis. However, the presence of additional genes in the BRCA2 interval is suggested as groups of putative exons and hybrid selected clones that were transcribed in consistent orientations could be localized to common physical intervals.

BRCA2 Protein↗
PubMed1996

[Is there a social consensus which defines and understands the problems of conjugal violence?].

Why is that some relationships, initially harmonious, tip into violence and abuse? Many studies have examined the phenomenon to attempt to circumscribe the incidence and seize its dynamics. These studies seem to bring out a social phenomenon of quite serious amplitude. Thus, according to a study conducted by MacLeod and Cadieux in 1980, one in ten women is battered on a regular basis. According to Statistics Canada, in 1993, 25% of Canadian women have been victim of violence by their partner since the age of sixteen. Among this group, 15% are still living with the same partner. Moreover, despite programs destined to help victims of conjugal violence, the number of cases declared appears to have diminished. Such alarming results have brought many researchers to study the problem further. In the last ten years, some progress has thus been realized in the understanding of the phenomenon of violence against women. Programs of intervention, government involvement, judiciarization of certain forms of abuse, sensitization of the public regarding conjugal violence as well as denunciation of cases of violence have marked this progress. In spite of a rising conscience regarding conjugal violence, research sometimes runs up against obstacles. In spite of complex modelization of concepts and factors of prediction of the phenomenon, results sometimes appear disappointing. Thus, is there a social consensus on a definition of the problem and its dynamics? The authors will try to answer this question by reviewing different theoretical approaches used to define conjugal violence. They will then attempt to make a critical analysis of these theories by examining different empirical studies realized in this field.

Domestic Violence↗
PubMed1995

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors.

Little is known about the effect of the host on the genetic stability of bacterial plant pathogens. Crown gall, a plant disease caused by Agrobacterium tumefaciens, may represent a useful model to study this effect. Indeed, our previous observations on the natural occurrence and origin of nonpathogenic agrobacteria suggest that the host plant might induce loss of pathogenicity in populations of A. tumefaciens. Here we report that five different A. tumefaciens strains initially isolated from apple tumors produced up to 99% nonpathogenic mutants following their reintroduction into axenic apple plants. Two of these five strains were also found to produce mutants on pear and/or blackberry plants. Generally, the mutants of the apple isolate D10B/87 were altered in the tumor-inducing plasmid, harboring either deletions in this plasmid or point mutations in the regulatory virulence gene virG. Most of the mutants originating from the same tumor appeared to be of clonal origin, implying that the host plants influenced agrobacterial populations by favoring growth of nonpathogenic mutants over that of wild-type cells. This hypothesis was confirmed by coinoculation of apple rootstocks with strain D10B/87 and a nonpathogenic mutant.

Acetophenones↗
PubMed1995

Importance of cysteines in the LDLR-related domain of the subgroup A avian leukosis and sarcoma virus receptor for viral entry.

The extracellular domain of the subgroup A avian sarcoma and leukemia virus (ALSV-A) receptor contains a region that is related in sequence to the ligand-binding motifs of the low-density lipoprotein receptor (LDLR). This domain contains six cysteines that are highly conserved between different members of the LDLR protein superfamily, and these residues are presumed to participate in intrachain disulfide bonds. To assess the importance of each cysteine in the ALSV-A receptor, individual or multiple cysteines were mutated to alanines and the altered receptors were tested for the ability to confer susceptibility to viral infection. Receptors bearing single mutations allowed subgroup A viral entry, albeit at less than wild-type levels. Receptors containing two or three substitutions were completely inactive if one of the changed residues was Cys-35 or Cys-50. Of the altered receptors tested, the only exception to this rule was a functional receptor which lacked both Cys-35 and Cys-50, an activity that was dependent on the presence of other cysteines in this protein. Most interestingly, a receptor containing both Cys-35 and Cys-50 but lacking the other four cysteines was completely functional. These results demonstrate the importance of Cys-35 and Cys-50 for viral entry mediated by the ALSV-A receptor and show that in the presence of these two residues, all of the other cysteines in this protein can be removed without loss of this function.

Alpharetrovirus↗
PubMed1994

Arrangement of a cluster of three mouse type I keratin genes expressed sequentially during esophageal-type epithelial cell differentiation.

Keratins are intermediate filament proteins expressed in epithelial cells. They are divided into two groups, type I and type II, that must associate to form filaments. The genes encoding these proteins are clustered in two type-specific loci. In stratified epithelia, differentiation of the basal cells is accompanied by a switch in the expression of keratin genes. However, how this switch is controlled is not yet understood. We report here the cloning and mapping of a 55-kb region surrounding the keratin 19 (K19) gene in the mouse genome. This gene encodes a type I subunit expressed in simple and complex epithelia, notably in nonkeratinizing stratified epithelia of internal organs. In these tissues, it is expressed in basal cells and not in suprabasal cells, where the main type I subunit is keratin 13. Using probes corresponding to highly conserved sequences in intermediate filament proteins, we mapped two other genes downstream from the K19 gene. Restriction mapping and sequencing data indicate that they encode the mouse K15 and K13. The three genes are separated by about 5-6 kb, and they are in the same transcriptional orientation. Because the three genes are expressed together in stratified epithelia and because their order of expression during differentiation is the same as their order on the chromosome, we suggest that there is a relationship between their genomic organization and the control of their expression.

Amino Acid Sequence↗
PubMed1994

Common origins of BRCA1 mutations in Canadian breast and ovarian cancer families.

Women who carry mutations in the BRCA1 gene on chromosome 17q have an 85% lifetime risk of breast cancer, and a 60% risk of ovarian cancer. We have identified BRCA1 mutations in 12 of 30 (40%) Canadian families with breast and/or ovarian cancer, including six of the eight families (75%) that contained two cases of early-onset breast cancer and two cases of ovarian cancer. Six frameshift mutations account for all 12 mutant alleles, including nucleotide insertions (two mutations) and deletions (four mutations). Four independent families carried the same 1 basepair (bp) insertion mutation in codon 1755 and four other families shared a 2 bp deletion mutation in codons 22-23. These families were not known to be related, but haplotype analysis suggests that the carriers of each of these mutations have common ancestors.

Amino Acid Sequence↗
PubMed1993

Macroscopic marital interaction coding systems: are they interchangeable?

The present study sought to determine the convergent validity of two macroscopic marital interaction coding systems: the Marital Interaction Coding System-Global and the Global Couple Interaction Coding System. The sample consisted of 40 couples who completed the Dyadic Adjustment Scale, the Potential Problem Checklist and a 30-min problem solving interactional task. Filmed interactions were coded by separate teams of observers using the Marital Interaction Coding System-Global and the Global Couple Interaction Coding System. Results showed that interobserver agreement, as assessed through intraclass correlations, was satisfactory for both coding systems. Between-system comparisons revealed that convergent validity coefficients were moderate; thus, it seems premature to conclude that macroscopic coding systems are interchangeable. Finally, multiple regression analyses indicated that both systems contained significant non-redundant behavioral predictors of marital adjustment. Implications of these results are discussed.

Adult↗
PubMed1991

Analysis of the promoter region of the gene encoding NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase.

Sequence analysis of the 5'-flanking region of the gene encoding NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase (NMDMC) revealed several putative cis-regulatory elements. To delineate the function of these regulatory elements, various deletion mutants of the 5'-flanking region were connected to the reporter gene chloramphenicol acetyltransferase (CAT) and promoter activity was measured in transient transfection assays. Transfection experiments performed with the sequence extending from -508 to +59 produced a high-level transient expression of the CAT gene in BALB/c 3T3-SV-T2 and NIH 3T3 cells. Removal of the sequence from +16 to +59 which includes the second transcription start point at +43, a TATA-like box and 5'-untranslated sequences abolished the promoter activity. Deletion analysis of 5'-upstream sequences revealed that the region from positions -55 to +59 is sufficient to mediate a high CAT activity comparable to the level obtained with the construct -508/+59. Within this region are found a CAAT box, a TATA-like box and two putative GC boxes. A functional analysis of the promoter showed that the sequence from -55 to +59 is sufficient to respond to stimulation by serum.

Aminohydrolases↗
PubMed1991

Structural organization of the murine gene encoding NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase.

The structural organization of the entire nuclear gene (NMDMC) encoding the mitochondrial (mt) NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase enzyme (NMDMC) was determined by analysis of clones obtained from a lambda EMBL3 murine genomic DNA library. The gene is approx. 13 kb in length and contains eight exons and seven introns. All exon/intron splice junctions follow the GT/AG rule. The amino acid presequence, which is essential for transport of the NMDMC enzyme precursor into mt, is encoded almost entirely in the first exon. Two major transcriptional start points (tsp), located 33 and 75 nucleotides upstream from the AUG start codon, were revealed by S1 nuclease mapping and RNase protection analyses. The immediate 5'-flanking region of the first exon contains one CAAT box, a TATA-like box and three sites homologous to the consensus sequence for the binding of transcription factor Sp1.

Aminohydrolases↗
PubMed1989

Isolation and characterization of cDNA clones encoding the murine NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase.

Forty cDNA clones corresponding to the bifunctional NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase enzyme were isolated from a mouse lambda gt11 library. Two classes of cDNA clones were shown by Northern analysis to correspond to the two mRNA species of 1.7 and 2.0 kilobases present in transformed cells but not in normal tissues and that apparently are derived from alternate polyadenylation signals. The 1050-base pair coding region encodes a protein of 350 amino acids which contains a putative mitochondrial-targeting signal peptide of 34 amino acids following the initiator methionine. The 20 amino acids immediately following the signal peptide correspond exactly to those determined by sequence analysis of the amino terminus of the purified protein. The derived amino acid sequence of the NAD-dependent dehydrogenase-cyclohydrolase shows extensive homology with the corresponding amino-terminal sequence of the trifunctional NADP-dependent dehydrogenase-cyclohydrolase-synthetase enzyme from human cells (approximately 40%), yeast cytosol (approximately 36%), and yeast mitochondria (approximately 45%).

Amino Acid Sequence↗
PubMed1986

Differential expression of keratin genes during mouse development.

Suprabasal layers of the newborn mouse epidermis contain two mRNAs of 2.0 and 2.4 kb which are translated into keratins of 59 and 67 kDa, respectively. To study their expression during development, cDNA sequences corresponding to the 2.0- and the 2.4-kb mRNAs were cloned, characterized by hybridization selection assay, and used as probes to detect keratin sequences in polyadenylated RNA from Day 11, 13, 15, and 17 embryos. In RNA from Day 11 of gestation, two RNAs of 2.8 and 1.8 kb were identified. They were found to have homologies with both epidermal RNAs, suggesting that they are coding for proteins of the keratin family. These two sequences were not detected in sample of later stages. RNAs comigrating with the two epidermal keratin RNAs were identified only in Day 15 and 17 embryos indicating that their expression was induced between Day 13 and 15. Finally, the localization of the 59-kDa keratin mRNA was examined by in situ hybridization. The spinous and granulous cell layers were found to be heavily covered with grains while other regions of the tissue sections were unlabeled. All these results support the hypothesis of a sequential expression of keratins during differentiation of epidermal cells and suggest that proteins related to the keratins expressed specifically in keratinizing cells are expressed earlier during development.

Animals↗