Faculty Bibliography

We have examined the arrangement of immunoglobulin heavy chain constant (CH) and joining (JH) region genes in murine T cell hybrid lines and in T lymphomas. CH genes derived from both parental cell types were present in all hybrids for which polymorphism in sequences flanking CH genes permitted us to distinguish parental CH genes. All T lymphomas and T cell hybrids retained the C alpha gene in germ-line configuration and all but one cell line had germ-line C mu genes. Novel DNA fragments reactive with JH probes were observed in six of nine T cell hybrids, as well as in two T lymphomas, WEHI7.1 and YAC-1, but not in the fusion parent, BW5147. No RNA homologous to C gamma 2b, C alpha, or lambda genes was detected in any of the T cell lines. T cell lines contained poly(A)+ RNA homologous to a C mu cDNA probe. More importantly, in several cell lines the C mu RNAs were associated with membrane-bound polyribosomes. These results suggest that both JH rearrangements and C mu RNA production occur in at least some mature, antigen-specific T cells. They may therefore reflect events in normal T cell development and function related to those involved in the generation of the T receptor for antigen

To determine the chromosomal location of the human alpha interferon genes, we scored a series of human/rodent somatic cell hybrids for the presence of DNA sequences hybridizing to an alpha 1 interferon DNA probe. The presence of human chromosome 9 in a hybrid correlated with the presence of a family of alpha interferon genes

A series of mouse-hamster somatic cell hybrids containing a variable number of mouse chromosomes and a constant set of hamster chromosomes have been used to determine the chromosomal location of a family of hormone-inducible genes, the murine caseins. Recombinant mouse cDNA clones encoding the alpha-, beta-, and gamma-caseins were constructed and used in DNA restriction mapping experiments. All three casein cDNAs hybridized to the same set of somatic cell hybrid DNAs isolated from cells containing mouse chromosome 5, while negative hybridization was observed to ten other hybrid DNAs isolated from cells lacking chromosome 5. A fourth cDNA clone, designated pCM delta 40, which hybridized to an abundant 790 nucleotide poly(A)RNA isolated from 6-d lactating mouse mammary tissue, was also mapped to chromosome 5. The chromosomal assignment of the casein gene family was confirmed using a mouse albumin clone. The albumin gene had been previously localized to mouse chromosome 5 by both breeding studies and analogous molecular hybridization experiments. An additional control experiment demonstrated that another hormone-inducible gene, specifying a 620 nucleotide abundant mammary gland mRNA, hybridized to DNA isolated from a different somatic cell hybrid line. These studies represent the first localization of a peptide and steroid hormone-responsive gene family to a single mouse chromosome

Immunoglobulin J chain mediates the polymerization of both IgM and IgA immunoglobulins. Its synthesis is closely regulated in B lymphocytes, apparently at the level of RNA transcription. To define the genetic bases of this regulation, we have determined the location and number of J chain genes in the mouse. Analysis of DNA from a group of somatic cell hybrids containing various mouse chromosomes on a constant background of Chinese hamster chromosomes indicated that this gene is located on mouse chromosome 5, unlinked to immunoglobulin heavy and light chain structural genes. Restriction mapping experiments further suggested the existence of a single J chain gene per haploid genome. This result was confirmed by quantitative analyses of band intensities yielded by Southern blots of mouse genomic DNA and J gene-containing plasmid DNA

We have mapped the genes for murine immunoglobulin lambda light chains to the region of chromosome 16 proximal to band B5 by hybridizing a cDNA probe for gamma light chains to the DNA of a series of hybrid clones made between mouse fibroblasts carrying Searle's translocation, T(X;16)16H, and Chinese hamster cells. Based on homology, we predict that the human Ig gamma gene (IGL) will map to the proximal two-thirds of HSA 22

The distributions of three human ribosomal gene polymorphisms among individual chromosomes containing nucleolus organizers were analyzed by using mouse--human hybrid cells. Different nucleolus organizers can contain the same variant, suggesting the occurrence of genetic exchanges among ribosomal gene clusters on nonhomologous chromosomes. Such exchanges appear to occur less frequently in mice. This difference is discussed in terms of the nucleolar organization and chromosomal location of ribosomal gene clusters in humans and mice

The chromosomal distributions of five families of mouse r-protein genes (S16, L18, L19, L30 and L32/33) were studied by Southern blot analysis of DNa from a panel of mouse-hamster hybrid cells containing various complements of mouse chromosomes. Our results indicated that members of a particular family are often located on more than one chromosome, that extensive clustering of many r-protein gene families on a few chromosomes is unlikely, and that there is no obligatory linkage of r-protein and rRNA genes

Several lines of evidence suggest a close functional relationship and a common evolutionary origin for alpha-fetoprotein and albumin. In the mouse, breeding studies have previously allowed the assignment of the albumin gene to chromosome 5. To test the possible linkage of alpha-fetoprotein and albumin, five somatic cell hybrids containing various combinations of mouse chromosomes, together with a constant set of hamster chromosomes, were tested for the presence of both genes using DNA restriction mapping techniques. Two of the five hybrids possessed both genes, and the other three lacked both. The only mouse chromosome present in the positive lines and absent from the negative ones was number 5, allowing the assignment of both genes to this chromosome

To determine the chromosomal localization of murine lambda light (L) chain structural genes, DNA from a panel of 11 mouse x hamster somatic cell hybrids was scored for the presence of sequences homologous to cloned lambda DNA probe molecules. Six of the hybrids had detectable lambda I and lambda II gene sequences. In all six, the full complement of murine sequences was present, and in its germline configuration. The remaining hybrids lacked any detectable murine lambda L chain gene sequences. The only mouse chromosome present in all of the positive hybrids and absent from the negative ones was number 16, allowing the assignment of lambda L chain structural genes to this chromosome. Together with the previous assignments of the kappa L chain genes to chromosome 6 and heavy chain genes to chromosome 12, this finding completes the mapping of Ig structural genes in the mouse at the chromosomal level