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C Petit

Publications and source records attributed to C Petit.

11 recordsLinked to original sources
PubMed2000

OTOF encodes multiple long and short isoforms: genetic evidence that the long ones underlie recessive deafness DFNB9.

We have recently reported that OTOF underlies an autosomal recessive form of prelingual sensorineural deafness, DFNB9. The isolated 5-kb cDNA predicted a 1,230 amino acid (aa) C-terminus membrane-anchored cytosolic protein with three C2 domains. This protein belongs to a family of mammalian proteins sharing homology with the Caenorhabditis elegans fer-1. The two other known members of this family, dysferlin and myoferlin, both have six predicted C2 domains. By northern blot analysis, a 7-kb otoferlin mRNA could be detected in the human brain. We isolated the corresponding cDNA, which is expected to encode a 1,977-aa-long form of otoferlin with six C2 domains. A 7-kb cDNA derived from the murine orthologous gene, Otof, was also identified in the inner ear and the brain. The determination of the exon-intron structure of the human and murine genes showed that they are composed of 48 coding exons and extend approximately 90 kb and approximately 80 kb, respectively. Alternatively spliced transcripts could be detected that predict several long isoforms (six C2 domains) in humans and mice and short isoforms (three C2 domains) only in humans. Primers were designed to explore the first 19 OTOF exons, henceforth permitting exploration of the complete coding sequence of the gene in DFNB9 patients. In a southwestern Indian family affected by DFNB9, a mutation in the acceptor splice site of intron 8 was detected, which demonstrates that the long otoferlin isoforms are required for inner ear function.

Alternative Splicing↗
PubMed1979

Genetic control of the immune response to the terpolymer L-glutamic acid 60-L-alanine 30-L-tyrosine10 (GAT). III. Restricted heterogeneity of the anti-GAT response from BALB/c responder mice.

The heterogeneity of the anti-GAT [terpolymer poly(Glu60, Ala30, Tyr10)] response of GAT responder mice has been analyzed. Purified anti-GAT antibodies from BALB/c mice belong only to the gamma 1 kappa subclass. The isoelectric focusing pattern obtained indicates that the anti-GAT antibodies are particularly basic and restricted. These results have been confirmed by two-dimensional polyacrylamide gel electrophoresis; by this technique, we have shown that the gamma 1 chain and the corresponding kappa chain of anti-GAT antibodies are restricted. All the anti-GAT antibodies from 10 BALB/c mice bear the cross-reactive GAT idiotype previously defined (J. Thèze and G. Sommé, Eur. J. Immunol. 1979, 9: 924). The present results indicate that the anti-GAT repertoire expressed in BALB/c mice is very limited.

Animals↗
PubMed1978

Comparison of the developmental kinetics of antibody- and immunoglobulin-forming cells in normal and tolerant mice.

The developmental kinetics of antibody-forming cells (AFC) and of cells synthesizing immunoglobulins without detectable antibody function against the antigen injected (IFC) were compared in lymph nodes of normal mice and tolerant mice receiving an immunogenic challenge. Tolerant states to bovine serum albumin (BSA), induced in adult mice, and to human gamma-globulin (HGG), induced in newborn mice, were studied. Whatever the tolerant state induced, the following main results were obtained: 1) both AFC and IFC were suppressed in tolerant mice, and this to approximately the same extent for the two populations; 2) both the suppression of the AFC and of the antigen-induced IFC were specific to the tolerogen used.

Animals↗
PubMed1977

Enzymatic variation at seven loci in nine natural populations of Drosophila melanogaster.

Allozyme polymorphisms at seven loci have been studied in nine natural populations of Drosophila melanogaster from the Saône and Rhône valleys sampled in 1973 and 1974. A great deal of polymorphism was observed; an individual was on the average heterozygous at 20.2% of its loci. The populations were genetically very homogeneous throughout the region sampled. The number of ovariolae per female varied from one group of populations to another depending on their geographical separation. Yet the number of ovariolae remained constant from one year to the next. The results show that migration alone cannot explain the homogeneity of the allozyme frequencies. It seems reasonable to conclude that selection plays a major role in maintaining the homogeneity of populations living in proximal biotopes.

Animals↗
PubMedDate not supplied

[Antibody producing cells and immunoglobulin synthesizing cells lacking antibody function].

After primary immunization the first immunoglobulin-synthesizing cells which appeared, contained immunoglobulins devoided of antibody function. These cells were progressively replaced by antibody synthesizing cells. The results we reported here demonstrated that except the repartition of Ig between IgM and IgG, there are no differences in the molecular composition and in the rate of biosynthesis between these two populations of cells.

Animals↗
PubMedDate not supplied

Development of immuneeoglobulin and antibody-forming cells in different stages of the immun response.

After primary immunization of mice, rats and rabbits with antigens (horse radish peroxidase, bovine serum albumin and muchroom tyrosinase) emulsified in complete or incomplete Freund's adjuvant, both cells synthesizing immunoglobulin without detectable antibody function and antibody-producing cells were detected. The first cells which appeared were synthesizing and secreting IgG and IgM immunoglobulins without antibody function. These cells were progressively replaced by cells synthesizing and secreting antibodies. In some plasma cells of mice, rats and rabbits immunized with peroxidase, antibody activity was detected only in restricted areas of the cytoplasm ; the remainder contained antigenic determinants of immunoglobulins. After secondary immunization the results were the following: in mice, both cells containing immunoglobulins without antibody function and antibody-containing cells appeared simultaneously and they were present in equal amount; in rats, only the antibody-containing cells were present in high number. Immunizations performed using different protein antigens (horse radish peroxidase, human and bovine serum albumin, aggregated and desaggregated human IgG, and ovalbumin) injected as a solution in saline have shown that after antigenic stimulation both populations of cells appeared, their number depending on the dose of the antigen injected. Further experiments carried out with tolerant mice, with germ-free animals and with "B" mice have shown that the appearance or not of antibody-producing cells was always related with respectively the presence or absence of cells synthesizing immunoglobulins without detectable antibody function. Finally experiments performed on rabbits have shown that some cells containing immunoglobulins without antibody function share idiotypic determinants in common with cells synthesizing antibodies.

Animals↗