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F Mami

Publications and source records attributed to F Mami.

7 recordsLinked to original sources
PubMed1988

Conservation of the immunoglobulin C lambda 5 gene in the Mus gene.

A gene encoding the lambda 5 light chain constant region was isolated from a genomic library from the SPE mouse strain (C lambda 5S). SPE is an inbred wild mouse strain belonging to the Mus 3 or Mus spretus group that has been genetically isolated from Mus 1 (the group to which laboratory mice belong) for a period of 1-3 million years. The sequence of the C lambda 5S gene shows strong homology to C lambda 5 of (C57BL/6J x DBA/2)F1 both in the coding region (98% identity) and in the 5'- and 3'-flanking regions (98 and 95% identity, respectively). Sequence comparison of C lambda 5 genes with C lambda 1 of BALB/c shows only few substitutions in the C lambda 5 coding regions and suggests that the three genes have a common ancestor. These data indicate that the C lambda 5 gene has evolved under strong selective pressure and probably encodes a functional gene product. The conservation of the C lambda 5 gene in various Mus species was observed by high stringency Southern blot analyses using a C lambda 5S probe on DNA sample from members of four different groups of wild mice. All the laboratory and wild mouse strains tested, including those with amplified sets of C lambda 1 and C lambda 2 hybridizing sequences, showed only single C lambda 5 hybridizing fragments. Little variation in size of restriction fragments detected with the C lambda 5 probe was seen in the different Mus species suggesting a high degree of conservation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1987

C lambda 2 and C lambda 4 immunoglobulin light chain genes in a wild-derived inbred mouse strain.

A genomic clone containing the lambda constant (C) region genes (C lambda 2S and C lambda 4S) has been isolated from a genomic library from the mouse strain SPE. SPE is an inbred strain derived from progenitors trapped near Grenada in Spain and has been classified as mus 3 or mus spretus. The sequence of the C lambda 2S gene is virtually identical to that of BALB/c both in the coding region and in flanking sequences, suggesting that it is an expressed gene in the SPE strain. By contrast, the C lambda 4S gene on the same cluster has diverged in sequence from that of BALB/c and contains a large deletion that precludes its normal expression. Whereas BALB/c J lambda 4 region contains substitutions that probably preclude its usage, the SPE J lambda 4 gene includes all sequences required for a functional J gene. Comparison of the C lambda 2S and C lambda 4S gene sequences with those available for BALB/c C lambda 3 and C lambda 1 confirms the close relationship between the C lambda 1-C lambda 4 and C lambda 2-C lambda 3 gene pairs. The C lambda 3 gene of BALB/c is more closely related to C lambda 2S than is C lambda 1 of BALB/c to C lambda 4S. If it is assumed that C lambda 1 and C lambda 2 are respective duplicates of C lambda 4 and C lambda 3 and that these duplications occurred at the same time, then the C lambda 2 gene has been under stronger selective pressure than C lambda 4.

Amino Acid Sequence↗
PubMed1986

The expression of the sIgD isotype in wild-derived mice.

IgD and IgM are concomitantly expressed on the surface of most mouse B lymphocytes and both molecules serve as receptor for antigen. In this communication we report that in contrast to IgM, which is expressed in a constant manner on the surface of spleen B lymphocytes of different laboratory and wild-derived mice, IgD expression is variable among the spleen cells of wild-derived mice. SPE, SEI, and SFM mice belonging to the Mus 3 subgroup show a fluorescence profile characterized by a marked diminution in the population of B lymphocytes expressing the IgD isotype; in addition, these cells have a low sIgD density on their membranes. These findings were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the iodinated membrane proteins. Polyclonal in vitro activation with lipopolysaccharide increases the frequency of surface IgD (sIgD)-bearing spleen cells and sIgD density in the SPE strain but decreases both the frequency and the density of IgD bearing cells in the BALB/c strain. This result suggests that delta gene expression is regulated differently in SPE and BALB/c mice. In addition, genetic analysis of sIgD expression in (BALB/c X SPE)F1 hybrids suggests that the proportion of sIgD-bearing cells and sIgD density are independently regulated.

Animal Population Groups↗
PubMed1986

Serologic variations in kappa light chains of various Mus species correlate with differences in gene structure.

Kappa light chains were investigated in sera of several groups of wild derived mouse strains by radioimmunological analysis using xenogeneic anti-mouse kappa light chain antibodies. Although the majority of strains tested expressed serologically indistinguishable kappa chains, several significant exceptions were observed. Anti-kappa chain reactivity was not detectable in normal sera of Mus caroli and Mus cervicolor species using specific antiserum. These strains express a variant of the kappa light chain. Some serologic variation was also observed in kappa chains from members of the subgenus Nannomys. Southern blot analyses using C kappa and J kappa probes indicated different patterns of hybridization in strains that were serologically distinguishable. Mus caroli and Mus cervicolor DNAs digested with the enzymes EcoRI or BamHI show variation from BALB/c and most other mouse strains tested in the size of the hybridizing fragments. This correlation between serologic and blotting analyses is no longer found in SJL and SPE strains, which show variation in BamHI cleavage but not at the serological level. The majority of laboratory and wild derived mice analyzed have the same pattern of hybridization. Taken together our results may also have implications for the phylogenetic classification of wild type mouse strains.

Animals↗
PubMed1982

The relationship between variable region determinants and antigen specificity on mitogen reactive B cell subsets.

On the basis of previous frequency determinations we could set up large numbers of cultures, each containing less than one competent precursor B cell specific for beta-galactosidase or for each of three idiotopes previously found on a monoclonal anti-beta-galactosidase antibody. Cultures were polyclonally activated by either lipopolysaccharide or Nocardia-delipidated cell mitogen. Each culture supernatant was individually tested for hemagglutination activity against sheep erythrocytes coupled with beta-galactosidase or with each of the three purified monoclonal anti-idiotypic antibodies. The results showed that only a minority of those clones positive for only one or two idiotopes recognized antigen. However, all those clones simultaneously positive for the three V region determinants recognized beta-galactosidase. The implications of these results for our understanding of the relationship between the antigen-binding site and idiotope expression are discussed.

Animals↗
PubMed1982

Mitogen-reactive B cell subpopulations selectively express different sets of V regions.

The experiments presented here were designed to investigate whether the idiotypic repertoire is equally distributed among B cells subpopulations as defined by mitogen reactivity. To this end we used lipopolysaccharides (LPS) and Nocardia delipidated cell mitogens (NDCM), which are two mitogens that have been described to act on different B cell subsets. The repertoire can be defined in quantitative terms as the frequency of B cells that are precursors for clones secreting immunoglobulin with a given specificity or with a determinate idiotype. We determined, therefore, the absolute frequency of LPS- and NDCM-sensitive B lymphocytes secreting immunoglobulin molecules that bear three idiotopes originally found on a monoclonal anti-beta galactosidase antibody. Because the frequencies of B cells carrying one of these idiotypes are dramatically different in the LPS- and NDCM-sensitive B cells subsets, we conclude that the idiotypic repertoire is not randomly distributed among mitogen-reactive B cell subpopulations.

Animals↗