Showing papers on "Genome published in 1968"
TL;DR: Hundreds of thousands of copies of DNA sequences have been incorporated into the genomes of higher organisms and used in medicine, science, and engineering.
Abstract: Hundreds of thousands of copies of DNA sequences have been incorporated into the genomes of higher organisms.
2,699 citations
TL;DR: The results support the conclusion that the pattern and evolution of late RNA abundances during T4 development has its origin in changing rates of transcription and not in changing stabilities.
271 citations
TL;DR: Cytological studies of 74 deficiencies of tomato chromosomes induced by radiation and identified by the pseudo-dominant technique reveal the loci of 35 genes on 18 of the 24 arms of the complement, and aspects of the frequently observed non-homologous pairing phenomenon are presented.
Abstract: Cytological studies of 74 deficiencies of tomato chromosomes induced by radiation and identified by the pseudo-dominant technique reveal the loci of 35 genes on 18 of the 24 arms of the complement. These findings integrated with data obtained from various trisomic types establish centromere positions, orientation of linkage groups, and markers on all but three of the arms. The prospects of obtaining a specific kind of deficiency for a given region were found to depend on : (1) kind of radiation applied, (2) (non-random) breakage frequency in different parts of the chromosome, (3) stability of broken ends, (4) tolerance of deficiency in different parts of the genome, and (5) relative vigor of the mutant homozygote used to detect the deficiency. Aspects of the frequently observed non-homologous pairing phenomenon are presented and discussed. Marker genes whose loci are known appear to be non-randomly distributed between and within chromosomes. Chromosome exchanges as determined by genetic crossing over and cytologically observed chiasmata are likewise non-randomly distributed between and within chromosomes.
124 citations
TL;DR: The basic technique was hybridization of RNA synthesized in infected or transformed cells to viral DNA, and hybridization competition experiments, and results partly similar to those reported here were recently published by Aloni et al.
Abstract: The expression of genes of the oncogenic virus SV40 is regulated. In productive infection, some genes are expressed before viral DNA replication begins (“early” genes); others are expressed after it has begun (“late” genes).1 In transformed cells, which contain the complete viral genome,2 some genes are expressed; others are not. Whether either type of regulation is at the level of transcription of viral genes is the question raised in the work to be reported here. The basic technique was hybridization of RNA synthesized in infected or transformed cells to viral DNA, and hybridization competition experiments. Results partly similar to those reported here were recently published by Aloni et al.3
122 citations
113 citations
92 citations
TL;DR: A collection of λbio transducing particles were isolated and the phage and bacterial extent of their genomes characterized, and the nature of the λdb particles conforms to the structural predictions of the Campbell model.
88 citations
TL;DR: While cells treated with actinomycin D appear to go through a survival maximum at the same age, they are most resistant after the completion of DNA synthesis; i.e. in G2 (or G2‐mitosis).
Abstract: A comparative study was made of the toxic properties of actinomycin D and X-rays using synchronized populations of Chinese hamster cells cultured in vitro. X-irradiated cells are most resistant in the latter half of the DNA synthetic period (late S). While cells treated with actinomycin D appear to go through a survival maximum at the same age, they are most resistant after the completion of DNA synthesis; i.e. in G2 (or G2-mitosis).
In spite of these differences, we found that actinomycin D damage in late S cells interacts with X-ray damage. Thus, a common locus for the site of actions of both agents is suggested which may be in or around the genome of a cell in view of the well-known DNA binding properties of actinomycin D.
72 citations
TL;DR: It is proposed that one or more of the Class I proteins exerts an active regulatory role in this shift of the synthesis from one class of proteins to another.
64 citations
TL;DR: The results suggest that gene duplication has been a major mechanism operative in the increase of DNA content of metazoans through evolution.
Abstract: A comparative study has been made of the reactions of bacteriophage T4, B. subtilis,and mouse DNA with homologous DNA trapped on a membrane filter. The variation of reaction rate with temperature provides information as to the number of unique and partially related base sequences. The thermal stability of the duplexes formed at various temperatures has been used as a criterion of the extent of base pairing. These studies suggest that no closely related base sequences exist within the T4 genome. Similar results were obtained with Bacillus subtilisDNA although the data suggest the possibility of some very distant intragenome homologies. In contrast, mouse DNA contains so many related base sequences that the predominant reaction product is always one containing partially complementary strands. These results suggest that gene duplication has been a major mechanism operative in the increase of DNA content of metazoans through evolution. The relationship between the existence of partial base sequence redundancies and the mechanism of recombination is also discussed.
59 citations
TL;DR: Relationships between the A and B genomes of the tetraploid Avena species and between these and the AS genome of the diploid A. hirtula and strigosa were studied in triploid (AS) species.
Abstract: Relationships between the A and B genomes of the tetraploid Avena species (A. magna excluded) and between these and the AS genome of the diploid A. hirtula and strigosa were studied in triploid (ASAB) and tetraploid (ASASAB) hybrids. Chromosome affinities were estimated on the basis of the karyotypes and the pairing behaviour of the chromosomes.The main findings were:1. The AS karyotype of the 2x and the A of the 4x species were identical and the chromosomes of the genomes A and B were similar. No difference was noticeable in the karyotypes of the 4x species studied. A nucleolar chromosome appeared from the B set in the 3x hybrids. It was concluded that the B genome is probably a modified form of A.2. All the chromosomes were capable of pairing in the ASAB and ASASAB hybrids. High degree of homology between the AS and A genomes was indicated by the high frequency of ring bivalents and ring-rod trivalents. The synaptic success of the B genome chromosomes (up to six trivalents) was interpreted as homoeology...
TL;DR: Evidence from the Annelida suggests that the diverse phosphagen kinases evolved in this way because the genome contains extra DNA with suitable coding properties that is provided by the duplication of a gene for a functionally related enzyme.
Abstract: The relationship between structure and function of proteins makes it unlikely that a new enzyme activity can evolve unless the genome contains extra DNA with suitable coding properties such as is provided by the duplication of a gene for a functionally related enzyme. Evidence from the Annelida suggests that their diverse phosphagen kinases evolved in this way.
TL;DR: The present experiment reveals that preferential activation of maternally derived alleles need not be a rule of development.
Abstract: The gene locus for the enzyme 6-phosphogluconate dehydrogenase belongs to that part of the genome which is activated at the beginning of embryonic development. The present experiment, utilizing three alleles at this autosomally inherited locus of the Japanese quail, was designed to show whether exhaustion of maternally stored 6-PGD is followed by maternally hemizygous de novo synthesis of the same enzyme. 6-PGD phenotypes of early embryos resulting from the mating between a male homozygous for one allele and a female heterozygous for two other alleles were examined by starch gel electrophoresis. The result showed that the maternally stored 6-PGD is exhausted before the twenty-fourth hour of incubation. This is followed by synchronous activation of both parental alleles. Previous studies on the development of various interspecific crosses have revealed that, at all loci studied, the activation of the maternally derived allele preceded that of the paternally derived allele. The present experiment reveals that preferential activation of maternally derived alleles need not be a rule of development.
TL;DR: Evidence is presented in support of the hypothesis that the genome of P. pilosa (= P genome) is shared by all of the polyploids, and the supporting evidence will be drawn from the geographical distribution and ecology, morphology, cytology and chemoprofile of the taxa.
Abstract: Polyploidy among the eastern North American species of Phlox is of limited occurrence. Of the 41 taxa only 5 are consistently polyploid and each is tetraploid, 2n = 28 (Flory, 1934; Meyer, 1944; Erbe and Turner, 1962; Levin, 1963, 1966a, 1967a; Levin and Smith, 1965; Smith and Levin, 1967). Four of the phloxes are closely related members of the P. pilosa complex as follows: P. aspera E. Nels., P. pulcherrima Lundell, P. villosissima (Gray) Whitehouse, and P. floridana Benth. The following discussion will deal with the genomic constitution and mode of evolution of these taxa. Evidence is presented in support of the hypothesis that (1) the genome of P. pilosa subsp. pilosa (= P genome) is shared by all of the polyploids, that (2) P. floridana and P. pulcherrima contain the genome of P. carolina subsp. angusta (= C genome) in addition to the P genome, and that (3) P. villosissima and P. aspera contain the genome of P. drummondii subsp. mcallisteri (D genome) in addition to the P genome. The supporting evidence will be drawn from the geographical distribution and ecology, morphology, cytology and chemoprofile of the taxa.
TL;DR: It is suggested that most nucleotide sequences in the rII genes, which are longer than 12 nucleotides, are not recurring in the T4 genome.
TL;DR: The determination patterns and rates of divergence of genes in related organisms affords a comparison with phyletic relationships determined by phenotypic traits and an approach to the detection of base sequence relationships within a genome utilizes techniques of specific duplex reactions of polynucleotides.
Abstract: HERE are many facets to the study of gene variability. The determination patterns and rates of divergence of genes in related organisms affords a comparison with phyletic relationships determined by phenotypic traits. On a molecular level, a geneiral approach has been the comparison of polynucleotide sequences by DNA/DNA duplex formation (DOTY et al., 1960) and RNA/DNA hybridization (MCCARTHY and BOLTON 1963) of nucleic acids from different organisms. A more detailed analysis is possible by coinparing structures of specific gene products of related organisms (see ZUCKERKANDL and PAULING 1965). A more limited set of relationships is revealed by the analysis of variants at a single locus within a population. Hemoglobin amino acid sequence data have proved useful in estimating the number and relationship of different alleles (see RUCKNAGEL and NEEL 1961). The detection of products of allelic genes extends this analysis to a number of loci (HUBBY and LEWONTIN 1966; HARRIS 1966). An additional set of relationships may exist among genes within the genome of a single organism. Thie well-known increase of DNA content per nucleus (with organism complexity (see MCCARTHY 1965) has encouraged speculation as to the mechanism by which more complex genomes have been generated through evolution. An important mechanism for the development of new base sequences may involve gene duplication followed by divergence (BRIDGES 1935). Again, the detailed amino acid comparisons of functionally related proteins have provided specific examples of this kind of gene evolution (WALSH and NEURATH 1964). Proteins with overtly different functions but related amino acid sequences have also been reported (BREW, VANAMAN and HILL 1967), and the number of these examples will surely increase. In Drosophila, gene duplications are wellknown. STURTEVANT (1925) reported a duplication at the Bar locus, leading to the suggestion that such duplications could be an important evolutionary process. Cytological comparisons of banding patterns in polytene chromosomes of Drosophila have provided (other possible examples of gene duplication (BRIDGES 1935). An approach to the detection of base sequence relationships within a genome utilizes techniques of specific duplex reactions of polynucleotides. Comparison of the rate of formation and the structures of these duplexes, with the correspond-
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Journal Article•
TL;DR: Much more experimentation will be required to delineate the information added to the cells during transformation and the viral genes required to effect and to maintain the transformed state.
Abstract: that suitable technics will detect differences between the trans formed cells and cells of the parental type. Markers often used to follow such transformation are changes in karyotype, in morphology, in antigenic makeup, and in the acquisition of tumorigenic potential. Although it is known that at least a portion of the virus genome persists following virus transfor mation of cells, little is known of the state in which the genome of DNA-containing viruses exists in the tranformcd cell, and much more experimentation will be required to delineate the information added to the cells during transformation and the viral genes required to effect and to maintain the transformed state.
TL;DR: Growth-rate mutations that were newly induced in haploid yeast by nitrosoguanidine were partially expressed in diploid heterozygous for these mutations only when the diploids were heterozygotes elsewhere in the genome, and when both haploids and diploidal were grown in a stress environment.
Abstract: Growth-rate mutations that were newly induced in haploid yeast by nitrosoguanidine were partially expressed in diploids heterozygous for these mutations only when the diploids were heterozygous elsewhere in the genome, and when both haploids and diploids were grown in a stress environment.
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Journal Article•
TL;DR: In euploid Drosophila, marked multiple-inversion stocks have proved useful for chromosome assay and methods which assess the genetic contribution of particular chromosomes or parts of chromosomes to the variability of a polygenic system are proposed.
Abstract: increasing number of contributions to our knowledge of quantitative inA!eritance and polygenic interactions have employed materials and techniques which partition the complex system statistically and experimentally. A major promise is greater understanding of the genetic, cytogenetic, and epigenetic architectures (GRANT 1964) of continuously varying traits. Especially fruitful are methods which assess the genetic contribution of particular chromosomes or parts of chromosomes to the variability of a polygenic system. Indeed, THODAY (1961) has proposed and shown that adequate techniques may permit the isolation and study of some of the individual gena ctic ’ components ( SPICKETT and THODAY 1966). In euploid Drosophila, marked multiple-inversion stocks have proved useful for chromosome assay. In this organism MATHER and HARRISON (1949 a,b) showed that all chromosomes affected differentially the number of abdominal chaetae, and BREESE and MATHER (1957, 1960) assayed six regions of chromosome 111 for effects on chaeta number and viability. ROBERTSON (1954) performed a chromosome analysis for the genetic effects of selection on body size. KELLER and MITCHELL (1962 a,b) have analyzed the interaction of X chromosomes and autosomes from three inbred lines for effects on certain morphological and viability traits. The technique has also been applied by MOHLER (1965) in the study of crossveinless-like strains; and by KEARSEY and KOJIMA (1967), who assayed the three main chromosomes from four different stocks for effects on body weight and egg hatchability. Employing aneuploid series in wheat (SEARS 1953a), the use of chromosome substitution lines (UNRAU, PERSON, and KUSPIRA 1956) promises a more detailed analysis of the polygenic structure of quantitative characters (AKSEL 1967). Using intervarietal chromosome substitution, LAW (1966, 1967) has analyzed the effect of allelic differences between chromosome 7B of two varieties of wheat for the characteristics of yield (grain weight, grain number, tiller number), height, and days to ear emergence. By an “inbred backcross line” technique (with some similarities in principle to monosomic substitution), WEHRHAHN and ALLARD (1965) have deduced evidence for four major genes with additive effects on heading time distinguishing two varieties of wheat. Another avenue of chromosome assay is opened in certain plant groups where
01 Jan 1968
TL;DR: Preliminary evidence suggests that A. 77mg7zn is a truly rare species in the Mediterranean region.
Abstract: The karyotype of the newly discovered tetraploid species A. nrngnn was described and comparzd with that of the other tetraploid species. While one set of chromosomes of A. nragnn is very similar to that of the As genome of some of the diploids and to that of the A genome of the other tetraploids, the second set of A. n z n p n is quite different from the second set (B) of the other tetraploids. Preliminary evidence suggests that A. 77mg7zn is a truly rare species in the Mediterranean region.