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Biomedical subjects

M Morisson

Publications and source records attributed to M Morisson.

8 recordsLinked to original sources
PubMed1998

Identification of 16 chicken microchromosomes by molecular markers using two-colour fluorescence in situ hybridization (FISH).

A feature of avian karyotypes is the presence of microchromosomes. As a typical avian genome, the chicken karyotype (2n = 78) consists of nine pairs of macrochromosomes, including the W and Z sexual chromosomes, and 30 pairs of indistinguishable microchromosomes usually ordered arbitrarily by decreasing size. Despite their reduced size, microchromosomes represent one-third of the genome and have a high gene density. So as to provide a tool to identify them, we developed a set of large insert-containing clones to be used as tags in two-colour fluorescence in situ hybridization experiments. Seventeen clones, six of which contain a microsatellite sequence and two others the fatty acid synthase gene or genes from the major histocompatibility complex, all presenting a strong hybridization signal, were selected for this purpose and enabled us to identify 16 different microchromosomes. The ability to recognize individual microchromosomes will be of great value for cytogenetic gene mapping, assignation of linkage groups from genetic maps and other studies on avian genome structure.

Animals↗
PubMed1998

Integration of chicken cytogenetic and genetic maps: 18 new polymorphic markers isolated from BAC and PAC clones.

As an approach to integrate the chicken genetic and cytogenetic maps, bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones were localized by fluorescence in situ hybridization (FISH) on chromosomes and by genetic mapping on the East Lansing and Compton reference families. Some of the clones used in this study were previously selected for the presence of potentially polymorphic (CA)n repeats and a microsatellite marker was developed when possible for genetic mapping. For other clones, a single strand conformational polymorphism (SSCP) was developed and used for this purpose. Between the two approaches, 18 markers linking the cytogenetic and genetic maps, seven on macrochromosomes and 11 on microchromosomes, were generated. Our results enabled the assignment and orientation of a linkage group to chromosome 3, together with the assignment of linkage groups to eight different microchromosomes, a fraction of the genome lacking mapping data and for which the degree of coverage by the genetic map was not well estimated previously.

Animals↗
PubMed1997

Associated effects of divergent selection for residual feed consumption on reproduction, sperm characteristics, and mitochondria of spermatozoa.

Eighteen generations of divergent selection for residual feed intake have been completed in two Rhode Island Red lines of domestic fowl. The high intake R+ line and the low intake R- line cocks used to sire Generation 19 of the selection experiment have been compared for associated responses on fertility, hatching, and sperm quality. Evaluations of sperm samples were based on volume, cell concentration, biochemical parameters (pH, uric acid and protein concentrations), and motility and morphology of spermatozoa. Finally, individual spermatozoa were analyzed by flow-cytometry (FCM) using Rhodamine 123 (Rh123) and nonyl-acrydine-orange (NAO) specific fluorochromes to assess, respectively, overall mitochondrial activity and overall mitochondrial content. Hatchability of incubated eggs was 20 points higher for the R- line, mainly because unfertilized eggs were only 6 vs 30% in the R+ line. Early embryo mortality was also twice as high in the R+ line (21%). The ratio of Rh123 to NAO fluorescence was identical for both lines. This result suggests that there was no difference in the energy producing potential of the individual mitochondria. Therefore, the difference seen for both dyes between the two lines might be attributed to a difference in the quantity of mitochondrial inner membranes present in the cell (with 17% less for the R+ line). In the R+ line, the poor performance at fertilization and during early embryonic development was associated with lower production of motile spermatozoa, possibly in relation to a lower quantity of mitochondria in spermatozoa from R+ cocks. Although the female contribution to the differences between lines was not explored separately, results suggest that selection for residual feed intake may have altered some cellular function related to the production of energy in the R+ line.

Analysis of Variance↗
PubMed1997

A deleted retroviral insertion at the ev21-K complex locus in Indonesian chickens.

Very poor feather development has been observed in chickens of the Nunukan strain, originating from Indonesia. The wing of the newly hatched chick does not show any primary or covert feathers; this phenotype will be referred to as very-late feathering (VLF). As adults, chickens are feathered but tail feathers are short and fragile. An experimental population was set up at the National Institute of Agronomic Research (INRA), Jouy-en-Josas, from one Nunukan male and four Nunukan females. Preliminary observations did not support the hypothesis of a sex-linked dominant mode of inheritance for the VLF phenotype. A restriction fragment length polymorphism (RFLP) study using five restriction enzymes and two probes, RAV-2 and endogenous virus (ev) ev21-int specific for the endogenous viral locus ALVE21, showed the presence of the expected 3' junction fragments for the ev21 occupied site but failed to reveal the expected 5' junction fragments for ev21 in Nunukan chickens. The unoccupied site corresponded to the ev21 unoccupied repeat (UR) of type a (URa). A deletion in the 5' region of the provirus and of the insertion site was indicated by the RFLP analysis and confirmed by a PCR study. Primers were designed in order to amplify a 5' junction fragment specific to the modified ev21 found in the Nunukan chickens. The sequence of this amplified product showed that the deletion started 652 bp upstream of the insertion site of ev21 and ended within the pol gene of the viral genome. This deletion represents a new allele, OSD, at the ev21 insertion site (locus ALVE21), that appears insufficient to produce a complete virus. Current data do not show a clear causal relationship between OSD and the VLF phenotype. The presence of OSD may be required but is not in itself sufficient to obtain the VLF phenotype. The genetic relationships between OSD and the altered feathering phenotype of Nunukan chickens will be investigated further in families segregating for the VLF phenotype, using the locus-specific PCR test developed as part of this study.

Alleles↗
PubMed1990

Sequence variability of bovine leukemia virus env gene and its relevance to the structure and antigenicity of the glycoproteins.

The nucleotide sequences of the env genes of seven bovine leukemia viruses and the encoded peptide sequence were compared, with the objective of (i) determining the genetic distance separating bovine leukemia virus isolates from different geographical regions, (ii) identifying particular amino acids that contribute to the sequential and conformational epitopes, and (iii) relating such epitopes to their projected position in a three-dimensional model of the structure of the gp51 surface glycoprotein. Two bovine leukemia virus subgroups were clearly identified, a Japanese-American subgroup represented by strains lambda BLV-1, VdM, and FLK-BLV and a European subgroup by strains T15-2, LB285, and LB59. It was possible to identify amino acids that were important in determining three of the epitopes (F, G, and H) recognized by neutralizing monoclonal and polyclonal antibodies. On the model, these epitopes were adjacent and located on the exposed region of the molecule. Amino acid sequences contributing to a fourth cryptic epitope were identified; as predicted by the model, they lay on the opposite side to the neutralizable epitopes in a region involved in glycoprotein subunit association. The fact that this region is not normally exposed on the virion surface provides further evidence for the validity of the model.

Amino Acid Sequence↗