Showing papers on "Chromosomal region published in 1981"

A new era in mammalian gene mapping: somatic cell genetics and recombinant DNA methodologies.

Abstract: Mammalian gene mapping techniques are now sufficiently advanced to contribute significantly to prenatal diagnosis and to human molecular genetics. Restriction fragment mapping can be used to place polymorphic genetic markers at random sites within the genome, and these sites used to assign genes responsible for disease conditions to a chromosomal region. Somatic cell genetic techniques can then be applied to saturate that region with additional restriction fragment markers, some of which will be closely linked to the disease gene. Closely linked restriction fragment markers, especially flanking pairs of markers, can act as predictors for the transmission of defective genes to offspring. A series of tightly linked flanking restriction markers might in addition contribute to the eventual isolation and cloning of the disease gene itself.

Specific integration of REV proviruses in avian bursal lymphomas

Abstract: The most common naturally occurring cancer of chickens associated with retrovirus infection is lymphoid leukosis (LL), a bursa (B) cell lymphoma. The primary causative agents are avian lymphoid leukosis viruses (LLVs), which do not necessarily have an oncogene. Recent evidence of Hayward et al.1 suggests that LLV infection promotes the expression of a cellular gene, c-myc (homologous to the oncogene of acute leukaemia virus, MC-29) thereby triggering the transformation process. In the majority of the tumours induced by LLV, the pro virus is integrated next to the c-myc gene (refs 1,3,18,19). To examine further the specific involvement of c-myc in lymphocytic transformation, we exploited our previous findings that replication-competent or non-defective reticuloendotheliosis virus (nd REV), genetically unrelated to LLV, are also capable of inducing lymphoma in chickens, with similar latent period and pathology to LL5. We have characterized the structure of the nd REV proviruses in the induced tumours and report here that proviral DNA is integrated next to c-myc in over 90% of the tumours analysed. This finding strengthens the hypothesis that the c-myc and its adjacent sequences are important in B-lymphocyte transformation. We also obtained evidence that amplification and structural alteration of the chromosomal region encompassing the REV provirus and c-myc gene have occurred during tumorigenesis in some of the tumours.

Distribution of Tn551 insertion sites responsible for auxotrophy on the Staphylococcus aureus chromosome.

Abstract: A method was devised to efficiently select isolates of Staphylococcus aureus 8325 in which Tn551, a transposon originating on the pI258 plasmid responsible for erythromycin resistance (Emr), had translocated to the host chromosome. This method consisted of selecting for Emr at 43 degrees C with a strain in which the pI258 plasmid was unable to replicate at 43 degrees C because of a temperature-sensitive plasmid mutation. By selecting isolates that were Emr at 43 degrees C and auxotrophic for nutrients not required by the parent strain. Tn551-induced auxotrophic mutants were readily isolated. The incidence of auxotrophic classes was not random; 80% of the isolates in one experiment were Trp-, whereas only a single example of each of some of the other classes was isolated. Among the Trp- mutants, the distribution of trp genes affected and the frequency of precise excision of Tn551 from individual sites varied. When analyzed by transformation, the Tn551-induced ala, his, ilv, lys, rib, thrA, thrB, and trp mutations were shown to occupy sites previously defined by nitrosoguanidine-induced mutations. Tn551-induced mutagenesis provided three previously unrecognized classes of auxotrophs (tyr, met, and thrC), and the Tn551 integration sites resulting in these mutations have been identified. In addition, a chromosomal region (uraB) was identified by Tn551 mutagenesis that is distinct from uraA (previously defined by chemical mutagenesis). Some Tn551-induced mutations (most notably pur) could not be linked to the known linkage groups of the chromosome by transformation. With the exception of two pur mutations, all of the Tn551-induced auxotrophic mutational sites cotransformed at unity with Tn551 and, in cases in which they were selected, prototrophic transformants were always Ems. Thus, the Tn551 and auxotrophic sites are identical.

Structural analysis of the three vitellogenin genes in Drosophila melanogaster

Abstract: Genomic fragments coding for sequences expressed as abundant mRNA in female Drosophila melanogaster were isolated from a lambda library. Hybridization of these clones to polytene chromosomes. in situ, identified four which mapped to X chromosomal region 9A to 9B, the locus for yolk proteins 1 and 2 (Ypl,2) and two which mapped to 12A6-7 to 12D3, the locus for Yp3. These clones were mapped with restriction enzymes, and the coding regions and regions of homology determined by Southern blots probed with cDNA, 5'-end-labelled RNA and nick-translated DNA. Heteroduplex and R-loop mapping confirmed that three of the clones carried two genes separated by about 1.4 kb and oriented in opposite directions. Southern blots probed with cDNA made from alkali-hydrolyzed RNA showed that these genes had their 5' ends next to each other. All 3 genes show homology to each other and have a main coding region of about 1.3 kb, the approximate size for the mRNAs.

Mapping of IS1 elements flanking the argF gene region on the Escherichia coli K-12 chromosome.

Abstract: Two directly-repeated IS1 elments have been mapped on the Escherichia coli K-12 chromosome at positions 23.2 kb and 34.5 kb counterclockwise of the IS3 element α3β3 by using F-prime plasmids (including the F lac- proAB+ plasmid F128) that carry different portions of the bacterial chromosome in the purE to proA region. Mapping was accomplished in part by construction of EcoRI, BamHI, and BglII restriction enzyme cleavage maps. Electron microscope heteroduplex and hybridization studies indicate that the chromosomal region flanked by these IS1 elements is completely homologous to the IS1-argF-IS1 region (Tn2901) on the P1argF5 transducing phage (York and Stodolsky, 1981), which suggests that the argF gene region in the usual E. coli K-12 strains has a transposon-like structure.

Interspecies MHS Relationships Studied by Serological and Cellular Cross-Reactions

Abstract: The major histocompatibility system (MHS) is an interrelated complex of genes located on a phylogenetically conserved chromosomal region involved in immunological processes. The gene products are transplantation antigens, Ia antigens, and complement factors. The precise relationship of these molecules to the multiple functions associated (in physiology and pathology) with the MHS is still unclear. It is characteristic of the MHS that an extensive series of alleles (a high degree of polymorphism) occurs at the individual gene loci.

The Major Histocompatibility Complex of Primates: Evolutionary Aspects and Comparative Histogenetics

Abstract: All mammalian species investigated have a chromosomal region designated as the major histocompatibility complex or m.h.c. The biological significance of the m.h.c. goes far beyond controlling the most important histocompatibility or transplantation antigens; the capacity to respond immunologically, the susceptibility to disease (including cancer), the serum level of several complement factors and numerous other biological traits are regulated by genetic systems closely linked within that chromosomal region. While the basic structure of the m.h.c. seems to be rather similar for all mammalian species, the similarities among the m.h.c. of human and non-human primates are particularly impressive. In this communication, m.h.c. gene products of rhesus monkey, chimpanzee and man are compared and reviewed. Evolutionary aspects of the persistence of the m.h.c. region or 'supergene' throughout the animal kingdom are discussed.

The HLA System

Abstract: The pioneer studies by J. Dausset, using leukocyte agglutinins from multiple transfused patients, and J. J. van Rood and R. Payne, using serum from women immunized by leukocytes during pregnancy, were followed by intensive studies which succeeded in defining a series of highly polymorphic loci very closely linked with each other on the short arm of chromosome 6. These studies received a great impetus from the experimental work in mice which had previously demonstrated homologous closely linked loci determining antigens which Gorer and Snell showed were important histocompatibility antigens, determining the rejection or survival of transplanted tissues (the H-2 system). The subsequent findings (1) that under experimental conditions humoral and cellular immune responses to certain synthetic antigens were determined by genes in the H-2 regions, and (2) that the occurrence of virus induced leukaemia was influenced by genes in this region, provided important clues as to the likely biological roles of this chromosomal region in immune regulation and in determining susceptibility or resistance to disease. For the clinical geneticist concerned with the analysis of the complex genetics of more or less common disorders, the findings of the associations between certain of the HLA antigens and many of these diseases have provided an important tool for genetic research. This has acted as a stimulus for new ideas concerning the pathogenesis of many clinical conditions. For a general review see Bodmerl.

Genetic analyses of alloreactions between recently wild and classical inbred strains of Syrian hamsters: evidence in favor of a major histocompatibility complex.

Abstract: Cytotoxic alloantisera were raised between recently wild and classical inbred strains of Syrian hamsters. Antisera produced by immunizing the classical inbred strains with tissue from the partially inbred, recently wild hamsters detect several specificities shared between the classical and recently wild strains. Reciprocal mixed lymphocyte reactions between the two different groups of hamsters suggest that the new source of hamsters possesses several unique MLR phenotypes which may represent new Hm-1 haplotypes. Moreover, several recently wild strains express MLR phenotypes quite similar if not identical to the Hm-1a haplotype of the inbred strain, MHA. Genetic analyses of alloreactions between domestic inbred and recently wild strains suggest that a single locus or chromosomal region encodes the allodeterminants that induce strong MLR reactivity. Six unique MLR phenotypes have been defined which most likely represent haplotypes of the hamster MHC equivalent, Hm-1. Genetic linkage studies indicate that some alloantisera detect determinants encoded by loci closely linked to the MLR locus, and therefore define Hm-1 determinants. Moreover, other alloantisera recognize determinants encoded by a locus that is unlinked to Hm-1. These studies suggest that Syrian hamsters express a polymorphic MHC equivalent, Hm-1, which encodes determinants that induce both cell-mediated and humoral alloreactivity.

Structure of H-2 Major Histocompatibility Complex Products

Abstract: The immune response is a reaction to a foreign or nonself substance. Intricately involved in this highly specific and tightly regulated protective-reaction mechanism are the gene products of the major histocompatibility complex (MHC) (Klein, 1975; Snell et al., 1976; Paul and Benacerraf, 1977; Gotze, 1977; Snell, 1978). This genetic system was referred to as the H-2 locus when it was initially recognized as a determinant of transplantation acceptance or rejection nearly 45 years ago by P.A. Gorer (1936). The serological and genetic features were gradually unraveled over the ensuing years. The complexity, both in terms of number of genes and in terms of polymorphism, led to the use of the term H-2 major histocompatibility complex to refer to this chromosomal region in the mouse. Similar MHC complexes have been found in other species (Gotze, 1977).

Suppression of ‘dot-like’ echanges in C-bands and late replicating DNA-rich regions of chromosomes

Abstract: An apparent suppression of ‘dot-like’ exchanges in C-bands and late replicating DNA-rich regions of chromosomes has been observed inAllium cepa. This result suggests that the occurrence of SCE very near each other could be avoided in these chromosomal regions.

Biochemical characterization of Syrian hamster cell surface alloantigens. III. Hamster alloantisera immunoprecipitate class II-like, but not class I-like, molecules.

Abstract: Twelve hamster alloantisera, recently produced by mutual immunizations of domestic inbred strains and recently wild, partially inbred lines, identify two cell surface molecules, 29 and 39 kilodaltons, expressed by hamster lymphohematopoietic cells. Their expression on lymph node and spleen cells suggests that hamster T cells display cell surface class II homologues. None of the alloantisera identify putative hamster homologues of class I MHC molecules. The data are consistent with the hypothesis that hamsters possess a chromosomal region, tentatively designated Hm-1, that comprises genetic loci encoding alloantigens detectable by mixed lymphocyte reactivity and by serology, a region that resembles the I region of murine H-2.

Genetic control of the expression of allelic Ig genes at the VH a locus in a1/a2 heterozygous rabbits

Abstract: Heterozygous rabbits representing 9 of 15 possible a1 and a2 heavy chain haplotype gene combinations among rabbits in the University of Illinois colony were analyzed for ratios of al to a2 in serum immunoglobulin (Ig). The Ig from rabbits of the a1x−y−n81f73g74de12,15 heavy chain haplotype in combination with any of three a2-associated heavy chain haplotypes have higher ratios of a1 to a2 than Ig from rabbits in which a1 is encoded by 4 other heavy chain haplotypes. For example, the mean a1: a2 ratio for adult a1x−y−n81f73g74de12,15/a2x32y33,− n82,f71g75de12,15 rabbits was 12:1 compared to 5:1 for a1x−y33,30n83,f71g75de12,15/a2x32y33,− n82,f71g75de12,15 heterozygous rabbits. Family studies indicated that the a1:a2 ratio was under the control of the heavy chain chromosomal region or a locus closely linked to it. Whether the regulation is due to varying numbers of VH genes and/or J gene segments, a separate regulator gene, or more efficient joining of certain gene segments, has yet to be determined.

Isolation and Analysis of a Cosmid Hybrid Containing the Human Genomic Interferon Gene, HuIFNβ1

Abstract: Human fibroblast interferon HuIFNβ has an anti-viral activity and can also stimulate natural killer cell action against neoplastic cells1 2 3. The IFNβ-gene belongs to a rare class of eukaryotic genes for which the immediate induction of transcription in response to certain inducers such as poly I:poly C has been demonstrated4 5 6. Recent findings indicate that two IFNβ mRNAs exist which are at the most only distantly related, but are co-ordinately induced in human fibroblasts7. It therefore seemed of great interest to isolate the chromosomal region for the IFNs1 gene so as to study the structure of the transcription unit, the possible adjacent transcription units, and the later application of this information to the production of interferon s in eukaryotic cells.

The actin genes of drosophila : homologous protein coding regions with distinct structural arrangements and chromosomal locations

Abstract: . We are investigating the structure and expression of the Drosophila melanogaster actin genes. Our findings are as follows. There are six actin genes per haploid Drosophila genome, and each gene is located in a distinct chromosomal region. The positions of introns within these genes are variable: DmA2 is split in the 5′ untranslated region, DmA4 within codon 13, and DmA1 and DmA6 within codon 307. The primary sequence of each Drosophila actin is like those of vertebrate cytoplasmic actins, except that in each case a cysteine precedes the three acidic residues of the N-terminus. We relate these findings to recently acquired data from actin genes of other species.