Showing papers on "Genome published in 1976"

Introduction to Genetic Analysis

Abstract: Genetics and the Organism PART I: TRANSMISSION GENETIC ANALYSIS: Patterns of Inheritance The Chromosomal Basis of Inheritanc e Eukaryote Chromosome Mapping by Recombination The Genetics of Bacteria and Their Viruses PART II: THE RELATIONSHIP OF DNA AND PHENOTYPE: From Gene to Phenotype Structure and Replication of DNA RNA and Transcription Proteins and Translation Regulation of Transcription PART III: GENOME STRUCTURE AND ENGINEERING: Recombinant DNA Technology Genomic Sequence Analysis Epigenetics The Dynamic Genome: Transposons and Genome Architecture PART IV: THE NATURE OF HERITABLE CHANGE: Gene Mutation and Crossing Over Large Scale Chromosomal Changes PART V: FROM GENES TO NETWORKS: Mutational Dissection Genetic Networks Cancer Developmental Genetics PART VI: THE IMPACT OF GENETIC VARIATION: Population Genetics Quantitative Genetics Evolutionary Genetics

DNA related to the transforming gene(s) of avian sarcoma viruses is present in normal avian DNA

Abstract: INFECTION of fibroblasts by avian sarcoma virus (ASV) leads to neoplastic transformation of the host cell. Genetic analyses have implicated specific viral genes in the transforming process1–4, and recent results suggest that a single viral gene is responsible4. Normal chicken cells contain DNA homologous to part of the ASV genome5–8; moreover, embryonic fibroblasts from certain strains of chickens can produce low titres of infectious type C viruses either spontaneously9 or in response to various inducing agents10. None of the viruses obtained from normal chicken cells, however, can transform fibroblasts, and results with molecular hybridisation indicate that the nucleotide sequences responsible for transformation by ASV are not part of the genetic complement of the normal cell11. We demonstrate here that the DNA of normal chicken cells contains nucleotide sequences closely related to at least a portion of the transforming gene(s) of ASV; in addition, we have found that similar sequences are widely distributed among DNA of avian species and that they have diverged roughly according to phylogenetic distances among the species. Our data are relevant to current hypotheses of the origin of the genomes of RNA tumour viruses12 and the potential role of these genomes in oncogenesis13.

Transposable genetic elements and plasmid evolution

Abstract: Transposable elements of DNA that are structurally defined and genetically discrete units seem to have an important role in the evolution of bacterial plasmids. Recombination occurring at the termini of such elements can result in the joining together of unrelated DNA segments that lack extensive nucleotide sequence homology. In addition, transposable elements serve as novel biological switches capable of turning on and off the expression of nearby genes as a consequence of their insertion into or excision from plasmid genomes.

The Construction in vitro of Transducing Derivatives of Phage Lambda

Abstract: Methods are described for the construction of plaque-forming, transducing derivatives of phage lambda, using appropriate receptor genomes and fragments of DNA generated by the restriction enzymes endo R.EcoRI and endo R.HindIII. The general properties of the transducing derivatives are described and discussed. Plaque-forming phages carrying the E. coli trp, his, cysB, thyA, supD, supE, supF, hsd, tna and lig genes have been isolated.

gag Gene of mammalian type-C RNA tumour viruses

Abstract: The translation product of the gag gene of mammalian type-C RNA viruses is a 65,000–68,000 molecular weight precursor polypeptide (Pr65) whose cleavage leads to the formation of four virion proteins, p30, p15, p12 and p10. An immunological approach has been used to establish the arrangement of the sequences coding for these proteins within the viral genome as (5′) p15–p12–p30–p10 (3′).

Endonuclease recognition sites mapped on Zea mays chloroplast DNA.

Abstract: The closed-circular DNA molecules of 85 × 106 daltons from Zea mays chloroplasts were isolated, digested with the restriction endonucleases Sal I, Bam I, and EcoRI, and the resulting fragments sized by agarose gel electrophoresis. A map of maize chloroplast DNA showing the relative location of all the Sal I recognition sequences and many of the Bam I and EcoRI recognition sites was determined. A DNA sequence representing approximately 15% of the Zea mays chloroplast genome is repeated. The two copies of this sequence are in an inverted orientation with respect to one another and are separated by a nonhomologous sequence representing approximately 10% of the genome length. The inverted repeats contain the genes for chloroplast ribosomal RNAs.

Genome structure of incomplete particles of adenovirus.

Abstract: Incomplete particles arising during productive growth of adenovirus were separated from infectious particles by density gradient centrifugation. The DNA contained in particles of low density was characterized by restriction enzyme analysis and by electron microscopy and heteroduplexing techniques. The DNA is heterogeneous in length, ranging in size from 15% of the normal genome to full length. Many individual molecules contain long, inverted terminal repetitions, which consist of the sequences extending from the normal left-hand end of the viral genome inward; the normal right end sequences appear to be missing from these molecules. The region of the genome reiterated in these molecules is that which has been implicated in transformation of rat cells by adenovirus (Gallimore, Sharp, and Sambrook, 1974; Graham, van der Eb, and Heijneker, 1974). A model for adenovirus replication is presented that accounts for the aberrant structures observed.

Mapping of the influenza virus genome. III. Identification of genes coding for nucleoprotein, membrane protein, and nonstructural protein.

Abstract: In previous communications we reported that the eight RNA segments of influenza A/PR/8/34 (HON1) virus could be distinguished from corresponding segments of influenza A/Hong Kong/8/68 (H3N2) virus by migration on polyacrylamide-urea gels. Examination of the RNA patterns of the two parent viruses and recombinants derived from them in concert with serological identification of surface proteins and analysis of the other proteins on sodium dodecyl sulfate gradient gels permitted the identification of the genes coding for hemagglutinin, neuraminidase, and the P1, P2, and P3 proteins (Palese and Schulman, 1976; P. Palese et al., Virology, in press). In the present report we have extended these observations using similar techniques to examine other recombinants and have identified the genes coding for the remaining virus-specific moving RNA segment as 1) and segment 6 of Hong Kong virus coding for the respective nucleoproteins, and that segment 7 of both viruses codes for the membtane protein and RNA segment 8 codes for the nonstructural protein. This completes the mapping of the influenza A virus genome.

Satellite DNA and cytogenetic evolution. DNA quantity, satellite DNA and karyotypic variations in kangaroo rats (genus Dipodomys).

Abstract: The genusDipodomys (kangaroo rats) exhibits major interspecies variations in the proportions of highly reiterated satellite DNA sequences in the genome as well as in the chromosome number and the proportions of uni-armed and bi-armed chromosomes. For nearly all of the approximately 22 species of the genus and several subspecies, liver DNA was distributed in neutral CsCl buoyant density gradients into four fractions: principal DNA (1.698 g/ml), intermediate-density DNA (1.702 g/ml), MS satellite (1.707 g/ml) and HS (heavy) satellites (1.713 g/ml). The total nuclear DNA content of diploid liver cells measured in eleven species by quantitative cytophotometry, ranged from 6.9 to 10.9 pg. These data were correlated with known features of the karyotypes of individual species. The salient findings were: (1) that interspecies variations in diploid chromosome number cluster at 52–54, 60–64 and 70–72 (2) that high total nuclear DNA was associated with high chromosome number, and with relatively large amounts of satellite DNA (3) that a high ratio of HS satellites to intermediate-density DNA was generally correlated with a predominance of metacentric and submetacentric chromosomes (high fundamental number). The relationships of satellite DNA to karyotype structure reveal a new level of hierarchy in the genome that appears capable of exerting global control over environmental adaptation and the evolution of new species. This mechanism is consistent with recent hypotheses that changes in the macro-structure of the genome are more important than point mutations in facilitating the rapid phases of animal evolution.

Telomeric satellite DNA functions in regulating recombination.

Abstract: Molecular and cytogenetical analyses of three sibling species of Australian grasshopper, Atractomorpha australis, A. species-1 and A. similis, resolves one of the long standing problems of highly repeated DNA. In this system satellite DNA functions in regulating the level and position of recombination, irrespective of whether the repeated DNA is located in telomeric or centric regions. — Even though the three species do not differ in their euchromatic genome sizes, their relative DNA contents are 1.00/1.10/ 1.41, the difference in genome size being due solely to visible centric or telomeric blocks of heterochromatin. — Antibiotic analytical and preparative ultracentrifugation, in situ hybridization and renaturation kinetic analyses reveal that a large cryptic satellite of A. similis constitutes the heterochromatic telomeric blocks of nearly all autosomes and that the DNA of this satellite is highly repeated. — Comparison of these grasshopper data with published literature of heterochromatic rearrangements in Drosophila and with heterochromatin distribution and recombination patterns in diploid plant species reveals that in every case heterochromatin is implicated in some form of alteration in the meiotic recombination system.

The relationship between the genome of triticum urartu and the a and b genomes of triticum aestivum

Abstract: Triticum urartu (2n = 14) was crossed with T. aestivum lines ditelosomic for chromosomes of the A and B genomes. Except for telosome 4Aα, the rest of the telosomes of the A genome paired in these h...

Nucleotide sequence organisation in the wheat genome

Abstract: Chromosomal nucleotide sequence organisation has been studied in hexaploid wheat, Triticum aestivum, using methods based upon the different renaturation kinetics of repeated and non-repeated sequences. Approximately 25 per cent of the wheat genome consists of non-repeated sequences. Nearly two-thirds of these (15 per cent of the genome) are around 1000 base pairs long interspersed between repeated sequences. Approximately 7 per cent of the genome consists of non-repeated sequences several thousand base pairs long. Less than 5 per cent of the genome consists of very much longer non-repeated sequences. Four per cent of the genome consists of extremely rapidly renaturing (fold-back ?) sequences. These sequences are distributed through at least 20 per cent of the genome. Between 50 and 65 per cent of the genome consists of repeated sequence DNA which is cleaved to duplexes approximately 400 to 800 base pairs long by S1 nuclease after renaturation in vitro. This implies that related repeated sequences frequently have different neighbouring sequences in the chromosomes. Repeated sequences (32 per cent of the genome) able to reanneal in very stringent incubation conditions are between approximately 350 and 650 base pairs long and are distributed through 85 per cent of the genome at intervals of less than 4000 base pairs. This distribution implies that short regions of essentially non-diverged repeated sequence DNA are interspersed with longer regions of diverged repeated sequence DNA in the chromosomes. Approximately 10 per cent of the genome appears to consist of very long repeated sequences or of long clusters of short, essentially identical repeated sequences.

Genetics of somatic mammalian cells: genetic, immunologic, and biochemical analysis with Chinese hamster cell hybrids containing selected human chromosomes.

Abstract: Through hybridization of specific Chinese hamster cell auxotrophs with human cells and selection in media lacking the nutritional supplements required by the former cells, a series of stable hybrid clones can be prepared. These hybrids have genomes consisting of a common part--the complete or almost complete set of Chinese hamster chromosomes, plus a variable part--one or a few human chromosomes. The identity of the human chromosomes can be varied by utilizing different Chinese hamster auxotrophs and the appropriate selective media. The human chromosomes present can be determined by a combination of cytogenetic analysis with chromosome banding and testing for specific human marker genes. Hybrids containing single human chromosomes 11 and 12 and the combination of both 11 and 12 are described. The system appears to lend itself to various studies such as identification of human cell surface antigens, determination of their chromosomal loci, measurement of their distribution among cells of normal human tissues, study of interrelations among syntenic and asyntenic genes, and mutational analysis of the human genome.

Complexity of germline and somatic DNA in Ascaris.

Abstract: DURING the early determination of the blastomeres in the nematode Ascaris chromosomal segments are eliminated in the presomatic cells (chromatin diminution). In the germline, however, all the chromatin is preserved. Similar genome differentiation phenomena have been published1–3. Since no molecular description of chromatin diminution has been made we have begun to study the chromosomes in germline and somatic cells4. It was found that the amount of DNA occurring only in the germ-line chromosomes is not constant5 and that this DNA is not enriched in rDNA6. There is no evidence that the germline-limited DNA is transcribed in vivo7. The results presented here show that the germline DNA of Ascaris contains highly repetitive components, eliminated by the diminution process. Their possible molecular function in connection with germline–soma differentiation and chromosomal behaviour is discussed.

Evolution of genome size by DNA doublings.

Abstract: Logarithmic distributions of nucleic acid contents per genome of species within major phylogenetic groups of organisms tend to form several peaks. These peaks appear to represent intragroup doublings of DNA or RNA which, in the case of eukaryotes, are independent of polyploidy. This phenomenon has been termed cryptopolyploidy. There are numerical similarities in peak values for different taxonomic groups. A high degree of order is suggested when minimum values for the major phylogenetic groups are plotted against a series of theoretical doublings. These data demonstrate the apparent existence of an exponential periodicity over eight orders of magnitude, leading us to suggest an evolutionary continuity of doublings of a basic ancestral genome (of about 300 nucleotides), these doublings being independent of both chromosome number and ploidy level. This proposed continuity encompasses most major life forms and is generally concomitant with increasing evolutionary complexity, particularly in the prokaryotes and lower eukaryotes. Our interpretation of the data presented here must currently be viewed as speculative, and we do not propose that genome doubling is the only mechanism for genome evolution. However, we feel that the evidence is sufficient to warrant serious scrutiny of our proposals. We hope that this approach to a synthesis of available data will provoke discussion and will stimulate further work toward either supporting, modifying, or disproving our hypothesis.

Changes in the expression of the chloroplast genome of Euglena gracilis during chloroplast development.

Abstract: The transcription program from the chloroplast genome of Euglena gracilis Z during light-induced chloroplast development has been characterized by hybridization of total cell RNA to 3H-labeled chloroplast DNA. Pancreatic DNase activated, purified Euglena chloroplast DNA was enzymatically labeled by Escherichia coli DNA polymerase I with [3H]TTP as a substrate. The [3H]DNA 'hybridization probe" was characterized by the kinetics of its renaturation with purified chloroplast DNA, and the thermal stability of [3H]DNA-DNA, and [3H]DNA-RNA hybrids. The [3H]DNA was hybridized in trace amounts to total cellular RNA extracted from Euglena cells 0, 4, 8, 12, 24, 48, and 72 h after the onset of chloroplast development. A large percentage (17%) of the chloroplast genome was found to be transcribed in dark adapted cells. Development is marked by an initial decrease in the fraction of the genome transcribed followed by an increase to 23% transcribed at the end of 72 h of light growth. Chloroplast RNA transcripts were also characterized by the kinetics of their hybridization to chloroplast DNA. The chloroplast specific RNA population is composed of three abundance classes, and the R0t1/2 for each class varies during the early stages of chloroplast development.

Bovine leukemia virus genes in the DNA of leukemic cattle.

Abstract: Reverse transcripts of the rna genome of the bovine leukemia virus (BLV) as well as 125I-labeled BLV RNA hybridize to the DNA of tissues from leukemic cattle with the adult form of the disease but not to bovine thymic lymphoma or normal bovine tissues.

Maintenance of genetic homogeneity in systems with multiple genomes.

Abstract: Genes or sequences of DNA present in multiple copies per cell include entire genomes of mitochondria and chloroplasts, nuclear ribosomal RNA genes, and highly repetitive sequences in heterochromatin. All copies are nearly identical, in spite of mutational pressure and weak selection. A zygote containing mitochondrial or chloroplast genophores of two different genotypes quickly produces progeny pure for one genotype or another (vegetative segregation). Evidence from yeast and Chlamy-domonas suggests that organelle genophores undergo repeated rounds of random mating and recombination. When two molecules carrying different alleles at a locus recombine, gene conversion can result in the cell becoming pure for one allele. Stochastic matching and conversion (SMAC) has been studied by computer simulations which suggest that it will tend to eliminate new mutations in yeast mitochondrial DNA and speed up vegetative segregation. We have verified previous suggestions that gene conversion, occurring during unequal mitotic sister-strand crossing-over, provides an efficient mechanism for maintaining the homogeneity of repeated sequences in eukaryotic chromosomes.

Non xenopus-like DNA sequence organization in the Chironomus tentans genome

Abstract: We have examined the sequence organization of Chironomus tentans DNA by means of optical and hydroxyapatite renaturation kinetics of total DNA fragment sizes of 0.36, 2.6 and 13.5 kilobases (kb) as well as isolated middle repeat DNA at sizes of 0.36 and 13.5 kb. 90% of the DNA renatured as unique sequences of a genome of 0.20 pg with the balance of DNA renaturing as middle repetitive sequences present on averge 90 times per haploid genome. At a DNA fragment length of 13.5 kb, 35% of the DNA was trapped on the hydroxyapatite as middle repetiitive fraction. We concluded C. tentans DNA to have a mean repeat length of about 4.3 kb distributed throuth out at least 35% of the genome with an inter repeat spacing of at least 13.5 kb but possibly being distributed throughout the whole genome with an inter repeat spacing of 36 kb. This shows C. tentans DNA organization not to follow the most ubiquitous Xenopus model but to be similar to the organization of Drosophila melanogaster DNA.

Do highly oncogenic group A human adenoviruses cause human cancer? Analysis of human tumors for adenovirus 12 transforming DNA sequences.

Abstract: Adenovirus 12 (Ad12) (Huie) (highly oncogenic group A) readily induces tumors in newborn rodents. Since Ad12 is isolated from human fecal samples, we investigated whether it plays a role in the etiology of human gastrointestinal cancer. If Ad12 is a causal agent of human cancer, then human tumors should contain Ad12 transforming genes, as indicated by studies of cells transformed in vitro and in vivo by oncogenic viruses. Ad12 DNA and the Ad12 transforming restriction fragment (EcoRI-C fragment, left 16% of the viral genome) were labeled in vitro to 10(7) to 4 X 10(8) cpm/mug by the nick translation reaction of DNA polymerase of Escherichia coli. The fidelity and sensitivity of these probes were established by (i) analysis of DNA from Ad12-transformed cells and from hamsters with tumors induced by Ad12, (ii) reconstruction experiments with added Ad12 DNA and EcoRI restriction fragments, and (iii) comparison of annealing characteristics with Ad12 probes labeled in vivo. With Ad12 [3H]DNA as probe, no viral DNA sequences were detected in 18 normal gastrointestinal tissues and 34 gastrointestinal tumors, including cancers of the colon, rectum, small intestine, and stomach, under conditions that would detect 0.1 copy of the Ad12 genome per tumor cell. Similar analyses of Ad12-transformed hamster cells and Ad12 primary hamster tumors indicated 6-18 copies per cell of over 90% of the viral genome. With the Ad12 EcoRI-C transforming fragment as probe, no hybridization was detected with 32 human gastrointestinal tumors and five normal tissues; this result excludes 1-2% of the Ad12 genome per tumor cell. Our date are strong evidence that Ad12 is not a major cause of human gastrointestinal cancer. The Ad12 transforming EcoRI-C fragment hybridized (50-68% efficiency) with other Ad12 isolates and with Ad18 and 31 (members of oncogenic group A), but not at all with 28 other human Ad serotypes (manuscript in preparation). Thus other group A members probably are also not involved in human gastrointestinal cancer. No viral DNA sequences were detected in 12 normal lungs and 22 lung tumors, suggesting that respiratory cancer does not involve an Ad12 etiology.