Biomedical subjects

J Duchaine

Publications and source records attributed to J Duchaine.

15 recordsLinked to original sources

PubMed1991

Biochemical and developmental characterization of the murine cluster of differentiation 1 antigen.

The cluster of differentiation-1 (CD1) antigens are major histocompatibility complex (MHC) class I-like glycoproteins belonging to the immunoglobulin supergene family. Initially described in humans, more recently putative CD1 encoding genes have been identified in several other species, including the mouse where it has been clearly demonstrated that CD1 mRNA is expressed. However, in the mouse both its unusually wide tissue distribution and the prevalence of incompletely spliced RNA have raised the possibility that the mRNA did not encode a functional protein. We have utilized a rabbit polyclonal antiserum raised against an Escherichia coli-expressed recombinant murine CD1 fusion protein to characterize the murine CD1 protein. Here we demonstrate that the antiserum binds specifically to a set of glycoproteins (49,000-55,000 MW) which contain a common core protein with both a size (36,000 MW) and tissue distribution in accordance with those predicted. During thymic ontogeny, this protein is highly expressed by Day 14 of embryonic development and persists into adulthood, while its pattern of expression in other organs changes significantly during development. Thus, the mouse provides an amenable model system for the study of CD1 function.

Animals↗

PubMed1989

Localization of molecules with restricted patterns of expression in morphogenesis: an immunohistochemical approach.

In a search for molecules with restricted patterns of expression during development, monoclonal antibodies were raised against different transitory structures of the chick embryo. Mice were immunized with cell suspensions from lightly homogenized embryonic tissues explanted from morphogenetically active regions. A convenient immunohistochemical assay was used to screen the hybridoma supernatants on a large scale. It relied on the use of poly(ethylene glycol) as embedding medium. Its water miscibility allowed, in a one-step incubation with antibody-containing supernatants, the dewaxing and rehydration of the tissue sections as well as antibody binding. We report here the usefulness of this approach in selecting monoclonals with unique patterns of immunoreactivity. In this study, cephalic neural crest cells in early or late phase of migration, together with their surrounding tissues, were used as immunogens. The monoclonal antibodies obtained have been classified into regional, cell-lineage, cell-cycle or extracellular material-associated markers. The information provided by the direct visualization of the immunoreactivity of the various monoclonal antibodies on tissue sections, as early as the first round of screening, allows rapid determination of the subsequent strategy to be followed for further characterization of the individual markers.

Animals↗

PubMed1987

Histological characterization of a monoclonal antibody raised against the branchial arches of the chick embryo: reactivity with myogenic lineages and a few non-mesodermal derivatives.

Monoclonal antibody A7H2 has been selected from a library of monoclonals raised against the branchial arch cells of 3-day-old chicken embryos, and its histological distribution was examined at different embryonic stages and levels. The immunoreactivity appeared during neurulation and was almost general in extraembryonic areas. As the embryo formed, A7H2-fluorescence disappeared from most tissues, but was concentrated in the splanchnomesoderm-derived smooth muscle lineages and epithelial linings of the coelomic cavity. A strong and durable reactivity was also observed in the myogenic condensations constituting the axis of the branchial arches, whereas myotomal cells of the differentiating somites were labelled more weakly and for a shorter time. Interestingly, non-mesodermal fluorescence was restricted to the branchial arch epithelium and some ectodermal placodes, to the thinning-out zones of the neural tube destined to form the choroid plexus, and to the pharyngeal and cloacal extremities of the digestive tract.

Animals↗

PubMed1984

Ecological distribution of Legionellaceae in the Quebec city area.

One hundred environmental water samples, which were collected in the Quebec city area and cultured on buffered charcoal yeast extract medium and three selective media, were inoculated to guinea pigs and were screened by direct immunofluorescent staining (DFA) for the presence of Legionellaceae. Six isolates were made (four Legionella pneumophila and two Tatlockia (Legionella) micdadei: three by animal inoculation and three by culture). No samples were simultaneously positive by both methods. After screening by DFA, 43 of the 100 samples were positive for Legionellaceae and 27 of those contained more than one serogroup and (or) species of Legionellaceae. Legionella pneumophila (serogroups 1 to 6) was the most frequent species seen by DFA. These results clearly show that Legionellaceae are frequent members of the freshwater microbial flora of the Quebec city area.

Culture Media↗

PubMed1970