The human desmin and vimentin genes are located on different chromosomes

We have used somatic cell hybrids of Chinese hamster X man and mouse X man to localize the genes (des and vim) encoding the intermediate filaments desmin and vimentin in the human genome. Southern blots of DNA prepared from each cell line were screened with hamster cDNA probes specific for des and vim genes, respectively. The single-copy human des gene is located on chromosome 2, and the single-copy human vim gene is assigned to chromosome 10. Partial restriction maps of the two human genomic loci are presented. A possible correlation of the des locus with several reported hereditary myopathies is discussed.     

The genes for human gastrin and cholecystokinin are located on different chromosomes

Summary The polypeptide hormones gastrin and cholecystokinin are structurally related, having the identical pentapeptide GWMDF located at their C-terminus. The precursors to these two hormones also show amino acid homology, suggesting that they may have a common ancestral origin. Recombinant DNA clones corresponding to gene fragments encoding human gastrin and cholecystokinin were used to determine their respective chromosomal localization by analyzing human-rodent cell lines. We have assigned the cholecystokinin gene to human chromosome 3q12-3pter and the gastrin gene to chromosome 17q.     

Chromosomal location in wheat of the genes coding for the acyl carrier proteins I and III

Communicated by J.W. Snape     

Genes controlling hydroxylations of phytosiderophores are located on different chromosomes in barley (Hordeum vulgare L.)

Phytosiderophores, mugineic acids, have been demonstrated to be involved in Fe acquisition in gramineous plants. In this study, chromosomal arm locations of genes encoding for biosynthesis of various phytosiderophores were identified in a cultivar of barley (Hordeum vulgare L. cv. Betzes). Using wheat (Triticum aestivum L. cv. Chinese Spring)-barley (cv. Betzes) ditelosomic addition lines for 4HS and 4HL, a gene for hydroxylation of 2′-deoxymugineic acid to mugineic acid was localized to the long arm of barley chromosome 4H. To locate the gene for hydroxylation of mugineic acid to 3-epihydroxymugineic acid, hybrids between the 4H addition line and other wheat-barley addition lines were studied. Only a hybrid between 4H and 7H addition lines produced 3-epihydroxymugineic acid. The gene was further localized to the long arm of chromosome 7H by feeding mugineic acid to ditelosomic addition lines for 7HS and 7HL. A new phytosiderophore was discovered in both 7H and 7HL addition lines, which was identified to be 3-epihydroxy-2′-deoxymugineic acid by detailed nuclear magnetic resonance studies. These results revealed that in barley there are two pathways from 2′-deoxymugineic acid to 3-epihydroxymugineic acid: 2′-deoxymugineic acid → mugineic acid → 3-epihydroxymugineic acid and 2′-deoxymugineic acid → 3-epihydroxy-2′-deoxymugineic acid → 3-epihydroxymugineic acid. Barley genes encoding for the hydroxylations of phytosiderophores are located in different chromosomes and each gene hydroxylates different C-positions: the long arm of chromosome 4H carries the gene for hydroxylating the C-2′ position and the long arm of chromosome 7H carries the gene for hydroxylating the C-3 position of the azetidine ring. Received: 10 August 1998 / Accepted: 30 September 1998     

The human genes for calbindin 27 and 29 kDa proteins are located on chromosomes 8 and 16, respectively

Genomic clones coding for the brain calcium-binding protein, calbindin 29 kDa, were isolated from a human library. A fragment containing exon 2 was used as a probe to investigate the presence of the gene in human x rodent somatic cell hybrids. The gene was unambiguously assigned to chromosome 16. The closely-related calbindin 27 kDa gene was previously assigned to chromosome 8. These two genes, deriving from a common ancestor, thus appear to have been separated during vertebrate evolution.     

5S-RNA genes of barley are located on the second chromosome

Summary The genes coding for 5S RNA in barley were cloned, sequenced, and their cluster was assigned to chromosome 2 using wheat-barley chromosome addition lines. High-resolution gel-electrophoresis of DNA and subsequent hybridization revealed new details of the organization of 5S DNA both in wheat and barley. The in situ hybridization of the cloned 5S gene with triploid endosperm nuclei also suggests that these genes are located in a single locus.On leave from: Department of Plant Breeding and Genetics, College of Agriculture, Orissa University of Agriculture & Technology, Bhubaneswar-751003, India     

Mammalian adenylyl cyclase family members are randomly located on different chromosomes

Molecular cloning studies have elucidated the presence of multiple isoforms of mammalian adenylyl cyclase. So far, six different isoforms (I to VI) have been fully characterized. Comparison of their structural and biochemical characteristics suggests that the mammalian adenylyl cyclase family can be classified into four sub-families: type I, type III, type II/IV, and type V/VI. We have determined the chromosomal localization of these genes. Type I gene was assigned to chromosome 7, type III to chromosome 2, types II and IV to chromosomes 5 and 14, and types V and VI to chromosomes 3 and 12. Our results indicate that the different adenylyl cyclase isoforms, even within the same subfamily, are distributed randomly in the genome, in contrast to the chromosomal organization of other components within the same signaling pathway, such as catecholamine receptors and G proteins.     

Characterization of two different acyl carrier proteins in complex I from Yarrowia lipolytica

Acyl carrier proteins of mitochondria (ACPMs) are small (∼ 10 kDa) acidic proteins that are homologous to the corresponding central components of prokaryotic fatty acid synthase complexes. Genomic deletions of the two genes ACPM1 and ACPM2 in the strictly aerobic yeast Yarrowia lipolytica resulted in strains that were not viable or retained only trace amounts of assembled mitochondrial complex I, respectively. This suggested different functions for the two proteins that despite high similarity could not be complemented by the respective other homolog still expressed in the deletion strains. Remarkably, the same phenotypes were observed if just the conserved serine carrying the phosphopantethein moiety was exchanged with alanine. Although this suggested a functional link to the lipid metabolism of mitochondria, no changes in the lipid composition of the organelles were found. Proteomic analysis revealed that both ACPMs were tightly bound to purified mitochondrial complex I. Western blot analysis revealed that the affinity tagged ACPM1 and ACPM2 proteins were exclusively detectable in mitochondrial membranes but not in the mitochondrial matrix as reported for other organisms. Hence we conclude that the ACPMs can serve all their possible functions in mitochondrial lipid metabolism and complex I assembly and stabilization as subunits bound to complex I.     

The genes coding for the muscle contractile proteins, myosin heavy chain, myosin light chain 2, and skeletal muscle actin are located on three different chromosomes

[This corrects the article on p. 1299 in vol. 1.].     

Developmental and pathogen-induced expression of three barley genes encoding lipid transfer proteins

Clones for three barley non-specific lipid transfer proteins (LTP2, LTP3, and LTP4; formerly Cw18, Cw20 and Cw21, respectively) which had been previously shown to inhibit growth of plant pathogens, were selected and characterized from a cDNA library derived from young etiolated leaves. Genes Ltp2 and Ltp4 were located in chromosome 3H and gene Ltp3 was assigned to chromosome 7H by Southern blot analysis of wheat—barley disomic addition lines, using gene-specific probes (3'-ends of cDNAs). These assignments were confirmed by the polymerase chain reaction, using specific primers. The three genes were expressed in stem, shoot apex, leaves and roots (at low levels) throughout development. Genes Ltp3 and Ltp4 were expressed at high levels, and Lpt2 at low levels, in the spike (rachis, lemma plus palea and grain coats). Neither of the mRNAs was detected in endosperm. The proteins were localized by tissue-printing with polyclonal antibodies in the outer cell layer of the exposed surfaces of the plant, throughout the embryo, and in vascular tissues. Expression levels in leaves were moderately increased by 0.34 M NaCl and by 0.1 mM abscisic acid and were not affected by cold, drought, salicylate, 2,6-dichloro-isonicotinic acid, ethylene or ethephon. Methyl Jasmonate (10 µM) switched off all three genes. Inoculation with Av6 or vir6 isolates of the fungal pathogen Erysiphe graminis increased the three mRNAs, especially that of LTP4, which reached a maximum nine-fold increase 12–16 h after infection.     

Isolation of duplicated human c-src genes located on chromosomes 1 and 20.

The oncogene (v-src) of Rous sarcoma virus apparently arose by transduction of the chicken gene known as c-src(chicken). We isolated DNA fragments representative of two src-related loci from recombinant DNA bacteriophage libraries of the human genome. One of these loci, c-src1(human), appeared to direct the synthesis of a 5-kilobase polyadenylated RNA that presumably encodes pp60c-src(human). Probes specific for the other locus, c-src2(human), did not hybridize to polyadenylated RNA prepared from a variety of human cell lines. Partial nucleotide sequence determinations of the loci demonstrated that c-src1(human) is highly related to chicken c-src and that c-src2(human) is slightly more divergent. The sequences imply that the final two coding exons of each human locus are identical in length to those of chicken c-src and that the location of an amber stop codon is unchanged in all three loci. c-src1(human) has been mapped to chromosome 20, and the second locus is located on chromosome 1. We conclude that c-src1(human) is the analog of c-src(chicken) and that the duplicated locus, c-src2(human), may also be expressed.     

The genes coding for the muscle contractile proteins, myosin heavy chain, myosin light chain 2, and skeletal muscle actin are located on three different mouse chromosomes.

The chromosomal distribution of murine genes expressed during differentiation of skeletal muscle cells was determined by Southern blot analysis of DNA from mouse-Chinese hamster hybrid cell lines containing incomplete subsets of mouse chromosomes. All detectable myosin heavy chain genes are located on chromosome 11. The gene for the myosin light chain 2 is located on chromosome 7. The skeletal muscle alpha-actin gene and several other actin genes, or pseudogenes, are located on chromosome 3. Additional actin DNA sequences are distributed on other mouse chromosomes.     

The gene and the pseudogene for mouse p53 cellular tumor antigen are located on different chromosomes.

The chromosomal assignments of the two genes encoding the murine p53 cellular tumor antigen were determined by using a panel of mouse-Chinese hamster somatic cell hybrid clones and a mouse p53-specific cDNA clone. One gene, probably the functional member of the family, was found to be on chromosome 11. The other gene, which is probably a processed pseudogene, was assigned to chromosome 14. The potential relevance of these findings to documented cases of chromosome 11 trisomy are also discussed.     

The gene encoding Escherichia coli acyl carrier protein lies within a cluster of fatty acid biosynthetic genes.

The gene encoding Escherichia coli acyl carrier protein (ACP) has been isolated and sequenced. The ACP gene (called acpP) was located on the genetic map between fabF and fabD which encode two fatty acid biosynthetic enzymes, 3-ketoacyl-ACP synthase II and malonyl CoA-ACP transacylase, respectively. An open reading frame between acpP and fabD encodes a 26.5-kDa protein that has significant sequence identity (greater than 40%) with two acetoacetyl-CoA reductases and thus is believed to encode a 3-ketoacyl-ACP reductase. This gene (called fabG) is cotranscribed with acpP. Thus, the gene encoding ACP, the key carrier protein of fatty acid synthesis, is located within a cluster of fatty acid biosynthetic genes.     

The var genes of Plasmodium falciparum are located in the subtelomeric region of most chromosomes.

PfEMP1, a Plasmodium falciparum-encoded protein on the surface of infected erythrocytes is a ligand that mediates binding to receptors on endothelial cells. The PfEMP1 protein, which is encoded by the large var gene family, shows antigenic variation and changes in binding phenotype associated with alterations in antigenicity. We have constructed a yeast artificial chromosome contig of chromosome 12 from P. falciparum and show that var genes are arranged in four clusters; two lie amongst repetitive subtelomeric sequences and two occur in the more conserved central region. Analysis of parasite chromosomes by pulsed field gel electrophoresis (PFGE) demonstrates that most contain var genes and two-dimensional PFGE has shown that var genes are located at chromosome ends interspersed amongst repetitive sequences present in the subtelomeric complex. Analysis of a var gene located in the subtelomeric region of chromosome 12 has shown that it has close homologues at the opposite end of the chromosome and in the subtelomeric region of two other chromosomes. This suggests that recombination between heterologous chromosomes has occurred in the subtelomeric regions of these chromosomes. The subtelomeric location of var genes dispersed amongst repetitive sequences has important implications for generation of antigenic variants and novel cytoadherent specificities of this protein.     

Cloning of human satellite III DNA: different components are on different chromosomes.

Two fragments cloned from purified human satellite III DNA do not cross-react with each other. One fragment, for which a partial sequence is reported, hybridises to satellite II as well as III and is shown to originate on chromosome 1. The other cloned fragment originates from the Y chromosome. This fragment has undergone considerable changes in size when cloned in lambda gt WES lambda B. Human satellite III is shown to consist of a number of non-cross-reacting sequences which nevertheless are related by the presence of closely spaced Hin F1 sites.     

Subfamilies of histone H3 and H4 genes are located on most,possibly all of the chromosomes in maize

Summary It has been previously shown that in the genome of maize the multiple copies of the histone H3 and H4 multigenic families are organized into eight to ten subfamilies each containing a variable number of copies. Each subfamily is characterized by a specific proximal environment and thus can be revealed by blot-hybridization with its specific 5 probe. Restriction fragment length polymorphism (RFLP) combined with monosomic analysis was used to localize several H3 and H4 subfamilies on maize chromosomes. H3 and H4 genes were found to be located on most, possibly all of the chromosomes, revealing a remarkably dispersed organization of these multigenic families.     

The genes coding for the cardiac muscle actin, the skeletal muscle actin and the cytoplasmic beta-actin are located on three different mouse chromosomes.

The actins are a group of highly conserved proteins encoded by a multigene family. We have previously reported that the skeletal muscle actin gene is located on mouse chromosome 3, together with several other unidentified actin DNA sequences. We show here that the gene coding for the cardiac muscle actin, which is closely related to the skeletal muscle actin (1.1% amino acid replacements), is located on mouse chromosome 17. The gene coding for the cytoplasmic beta-actin is located on mouse chromosome 5. Thus, these three actin genes are located on three different chromosomes.