Gene-enzyme Systems Research Articles

Genetic diversity in leukemia-prone feral house mice infected with murine leukemia virus.

The Lake Casitas (LC) mouse population located in south western Ventura county in California is unusual insofar as 85% of these mice are persistently viremic with congenitally transmitted murine leukemia virus (MuLV). The virus has been identified as the etiological agent responsible for lymphoma and neuromotor paralysis in large numbers of the mice. The majority of other wild mouse populations are generally free of infectious MuLV despite the presence of endogenous cellular DNA sequences homologous to infectious virus isolated from wild mice. Electrophoretic variation in 46 gene-enzyme systems was surveyed using mice from Lake Casitas and from a virus-negative population located in Bouquet Canyon (BC) approximately 40 miles from Lake Casitas. The LC and BC populations are genetically very similar to each other and to feral mouse populations previously studied in California and Europe. In the LC population 24% of the loci are polymorphic compared to 17% in the BC population. The average heterozygosities for the LC and Bc populations are 0.094 and 0.073, respectively. The large amount of genic variation in LC fails to support the concept of the derivation of the colony from a small number of founders. Tests for linkage disequilibrium and/or selective association of viremia and polymorphism at 15 loci located on nine mouse chromosomes did not reveal any nonrandom assortments. The viremic LC population, then, appears indistinguishable within the limits of experimental resolution from the virus-negative BC population in its population genetic structure.

Experimental studies on some genetic effects of marine pollution

Following the results of a series of investigations carried out to estimate the degree of marine pollution by utilizing certain marine filter feeders, such as the blue musselMytilus galloprovincialis, research has been planned to detect possible genetic effects of pollutants, with special attention to those acting at the population level. The possible selective role of pollutants has been studied both in natural (Mytilus) and in experimental (Tisbe holothuriae) populations by utilizing some electrophoretically-detected gene-enzyme systems as genetic markers. For some of the seven polymorphic loci studied inMytilus (AP, LAP, 6-PGD, IDHs, IDHm, PGI, PGM) significant changes in gene frequencies have been detected which can be related to the degree of pollution in the sampling areas. In the more polluted areas these changes were accompanied by a decrease in the frequency of heterozygotes. Similar changes in gene frequencies also occurred in laboratory populations of the copepodTisbe, reared under various experimental conditions. In particular, certain alleles of two loci, PGI-1 and AP-1, exhibited an increase in frequency, especially in populations cultured at various levels of oil pollution. This trend appeared more significant for the locus PGI. The fact that equilibria are reached and that the less favoured alleles are nevertheless maintained in the populations, even at extremely low frequencies, suggests the balanced nature of these enzyme polymorphisms. The significance of the above findings is briefly discussed.

A molecular approach to the identification and individualization of human and animal cells in culture: Isozyme and allozyme genetic signatures

The electrophoretic resolution of a group of genetically monomorphic gene-enzyme systems that are developmentally and biologically ubiquitous has been used to provide a species-specific and type-specific biochemical characterization of various cultured cells. The relative mobilities of gene-enzyme systems representing nine distinct gene products from cell cultures of 25 species from Drosophila to man are presented. These isoenzymes effectively discriminate interspecies cell-to-cell contamination and almost invariably serve to identify the contaminating species. The resolution of eight polymorphic gene-enzyme systems in human cell cultures provides a virtually unique allozyme genetic signature as a monitor of intraspecies cellular contamination. The genetic signatures of 47 commonly used human cells are presented. Included in the test were seven putative HeLa (human cervical carcinoma) contaminants each of which expressed a signature identical with that of HeLa. The probability that an unrelated human cell line will have a signature identical to a typed cell is computed for each line from the genotypic frequencies at each locus in a population of cultured human cells. The gene frequencies of this cell population are comparable to the same frequencies in natural human populations. The most common human signature has a frequency (and therefore a probability) of 0.02. The majority of the 17,010 possible signatures are far less probable. A calculation of the theoretical incidence of chance matching of signatures within test groups of two or more individuals is presented. The probability of a chance match between any two randomly selected individuals is 0.004 and among five randomly selected individuals is 0.034. The allozyme genetic signature represents a definitive monitor of cell identity and is presented as a standard of cell and tissue identification for a variety of biological studies.

Electrophoretic studies of gene-enzyme systems: Microevolutionary processes and phylogenetic inference

Abstract Electrophoretic studies of gene-enzyme systems: microevolutionary processes and phylogenetic inference Some main contributions to evolutionary population biology and systematics from electrophoretic studies of gene-enzyme systems are reviewed. The following topics are in particular discussed: 1. statistical methods for estimating genetic divergence; 2. variability of enzyme loci and their contribution to genetic distance; 3. patterns of genetic differentiation during the speciation process and the levels of divergence between taxa of different rank; 4. identification of sibling species and detection of reproductive isolating mechanisms; 5. phylogenetic inference from electrophoretic data and the construction of dendrograms; 6. congruence between electrophoretic and morphological data in taxonomy. 7. It is concluded that electrophoresis is a powerful tool in the study of microevolutionary processes and significantly contributes, at the lower taxa level,' to a systematic arrangement more consistent...

Isozyme studies on the association of the herpes simplex virus type 1 thymidine kinase gene with human chromosomes in somatic cell hybrids

To investigate chromosomal site(s) of integration of the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) gene in biochemically transformed [HeLa(BU25)/KOS 8-1] cells, these human cells which had been transformed by ultraviolet light-irradiated HSV-1 were fused with TK-negative mouse LM(TK-) cells, human-mouse somatic cell hybrid clones (LH81 clones 1-20) were isolated by HATG-ouabain selection and their chromosomes and isozymes were analyzed. Electrophoretic and serological analyses showed that all 20 clones expressed type-specific HSV-1 TK. Isozyme analyses on 29 gene-enzyme systems representing 22 human chromosomes revealed that all of the HSV-1 TK-positive clones expressed human aminoacylase-1 (ACY-1) and esterase D (ESD), which have been mapped to human chromosomes 3 and 13, respectively. Other human isozymes were detected in only one to four clones or in none of the clones. Chromosome analyses showed that: (1) the hybrid clones retained only a few human chromosomes; (2) a marker chromosome, designated M7, consisting of a chromosome 17 translocated to the short arm of chromosome 3, occurred in 36 out of the 41 metaphases examined of LH81-4 clones 1 to 4 and in 31 out of the 33 metaphases examined of LH81-12 clone 10; (3) a modified M7 chromosome, (M7/m), in which the distal 2/3 of the long arm of M7 was translocated to a small acrocentric mouse chromosome, was the only human chromosome found in metaphases of LH81-13 clone 17; and (4) an intact human chromosome 13 was not present in LH81-12 clone 10 or LH81-13 clone 17 cells. Counterselection with BrdUrd resulted in the isolation of subclones lacking HSV-1 TK, human ACY-1 and ESD, and the human marker M7 chromosomes. The experiments indicate that the HSV-1 TK gene is probably associated in HeLa (BU25)/KOS 8-1 cells with marker chromosome M7, but the possibility is not excluded that the segment of human chromosome 13 which codes for ESD is involved.

Characterization of the WIDR: a human colon carcinoma cell line.

We describe the establishment and characterization of WiDr, a cell line derived from a human colon carcinoma. It produces carcinoembryonic antigen in culture, and has a doubling time of 15 hr with plating efficiency of 51%. The HLA antigenic profile and the allozyme genetic signature (composed of eight gene-enzyme systems) of WiDr cells are different from those of HeLa cells. Furthermore, WiDr cells possess three marker chromosomes, again distinct from the HeLa marker chromosomes. Finally, it is highly tumorigenic in four different xenogeneic animal models. Based on these studies, WiDr represents a useful model cell line for tumor cell biology investigations.

Biochemical genetic variation and evidence of speciation in Chthamalus barnacles of the tropical eastern Pacific Ocean

Gene-enzyme variation was studied electrophoretically within and between barnacle populations of the genus Chthamalus from 8 intertidal stations from central California to the Pacific coast of Panama. Horizontal starch-gel electrophoresis separated and resolved 18 enzymes from 512 individual barnacles. A maximum of 25 gene-enzyme systems was interpretable from the resulting zymograms. Electrophoretic phenotypes and patterns of phenotypic variation generally conformed with those observed in other organisms. The amount of genetic variation within barnacle populations varied; average heterozygosity, for example, ranged from a low of 3.4% in a Mexican population of the C. fissus group to a high of 10.4% in C. anisopoma from the Gulf of California. Observed and expected average heterozygosities agreed in all population samples, indicating that these species are outbreeding. In contrast to the prediction stemming from a hypothesis that trophic stability regulates the amount of genetic variation in marine species, average heterozygosity tends to be positively correlated with latitude. Data from these and other barnacle species may support a hybrid “environmental heterogeneity-trophic diversity” model recently proposed to explain genetic variation in decapod crustaceans. Juxtaposition of individuals from different localities revealed numerous genetic differences among populations of the C. fissus group. At least three partially sympatric sibling species are separated by genetic distances as large as those observed between the C. fissus group and the distinct species C. dalli and C. anisopoma. A cladistic analysis places C. anisopoma close to the Mexican and Panamanian sibling species, with C. fissus from San Diego and C. dalli successively farther removed.

A gene ( Bevi) on human chromosome 6 is an integration site for baboon type C DNA provirus in human cells

Human VA-2 cells infected with baboon type C virus were cloned and fused to Syrian hamster cells, and 33 primary hybrid colonies were obtained. These cells segregated human chromosomes and retained the complete hamster genome. Assays for type C viral p30 antigen and reverse transcriptase were performed in conjunction with analyses of 30 gene-enzyme systems representing 22 different human chromosomes. The results confirmed that a gene, Bevi, previously assigned to human chromosome 6, dominantly controls baboon type C virus expression in hybrid cells. Representative hybrid clones were studied by nucleic acid hybridization techniques for the presence of integrated proviral DNA using complementary 3H-DNA transcripts of the baboon viral RNA genome. For each of 12 clones examined, there was a concordance between the presence of human chromosome 6, the presence of baboon type C proviral DNA sequences and virus expression. Clones which segregated chromosome 6 as judged by isozyme and karyological analyses lost detectable proviral DNA sequences and failed to produce virus. No syntenic association between the replication of baboon virus and the presence of 21 other human chromosomes was detected. We conclude that Bevi is a preferred integration site for the baboon type C provirus in the human genome.

Enzyme Polymorphisms as Genetic Markers in the Avocado

Cultivated varieties (cvs) of the avocado (Persea americana) originate by selfing, hybridization or chance selections, and are then propagated by grafting. The mesocarps of a given cv are consequently all genetically identical. Mesocarp gene-enzyme systems were examined by starch gel electrophoresis and were found to be highly polymorphic. Alcohol dehydrogenase, phosphoglucomutase, glutamic-oxaloacetic transaminase and leucine aminopeptidase are coded by 10 genes with 20 condominant alleles. ‘Seedling’ populations have been produced by selfing or by hybridizing cvs. Seedlings were found to segregate in normal Mendelian fashion for any gene for which the parent or parents were heterozygous. No isozyme evidence contradicted the reported parentage of several cvs of hybrid or selfed origin. Outcrossing, as indicated by the presence of a non-parental isozyme, was detected among the seedlings of a supposed selfed population. To our knowledge, this is the first report of molecular genetics and of the genetics of any single-gene character for the avocado. Possible applications are discussed.

Isozyme and allozyme patterns in embryonic Drosophila cell culture lines.

Two independently derived embryonic Drosophila cell culture lines were examined for 19 gene-enzyme systems. At two loci, alpha-glycerophosphate dehydrogenase on chromosome 2, and isocitrate dehydrogenase on chromosome 3, allelic variation was detected. These can now serve as genetic markers to identify hybrid cell clones. Quantitative differences between cell lines were found for five enzymes.

Low specific activity of rare allozymes of α-glycerophosphate dehydrogenase in Drosophila

ELECTROPHORETIC surveys of Drosophila species1 show that many gene–enzyme systems are essentially monomorphic. Very often, however, one or more populations may contain rare alleles, that is, at frequencies less than 5%. Are these alleles selectively neutral and rare because of historical accidents2 or are they deleterious and maintained in populations only through mutation? The dimeric enzyme α-glycerophosphate dehydrogenase (αGPDH) is a good example of an essentially monomorphic Drosophila gene–enzyme system. Out of the 101 species of Drosophila surveyed thus far for electrophoretic variation of αGPDH (refs 3–5), only D. melanogaster is polymorphic. This polymorphism seems to be maintained by selection with temperature being, or strongly correlated with, the selective agent6–8. Microcomplement fixation experiments indicate that this enzyme is evolving slowly among Drosophila species and has accepted relatively few changes in its structure9. We propose that the rare alleles of the αGPDH locus found in some species (see ref. 5) may be at low frequencies because the products of these alleles (allozymes) are catalytically less efficient than their ‘wild-type’ counterparts.

Enzyme polymorphisms as genetic signatures in human cell cultures.

The electrophoretic resolution of seven relatively polymorphic human gene-enzyme systems expressed in tissue culture cells can be used as a sensitive genetic monitor for intraspecific cell contamination. An identical genotype at each of the same allozyme loci provides a 95% (or greater) confindence estimate of the identity of two cultured lines, on the basis of the allelic frequencies of the seven enzyme loci in natural populations and in populations of independently derived cultured cells. Of 27 commonly used human cell lines examined, only one of 351 pairwise comparisons proved genetically indistinguishable.

Gene—enzyme systems in Drosophila

FEBS LettersVolume 70, Issue 1-2 p. 284-285 Book reviewFree Access Gene—enzyme systems in Drosophila Vol. 6 in the series Results and Problems in Cell Differentiation by W. J. Dickinson and D. T. Sullivan Edited by W. Beerman, J. Reinert and H. Ursprung Springer-Verlag; Berlin, Heidelberg, New York, 1975 x + 164 pages with 32 figures. DM 58.00, $ 25.30 B.A. Kilby, B.A. KilbySearch for more papers by this author B.A. Kilby, B.A. KilbySearch for more papers by this author First published: November 01, 1976 https://doi.org/10.1016/0014-5793(76)80779-XAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume70, Issue1-2November 01, 1976Pages 284-285 RelatedInformation

Gene-Enzyme Systems in Drosophila. Results and Problems in Cell Differentiation. W. J. Dickinson , D. T. Sullivan

Previous articleNext article No AccessNew Biological BooksGene-Enzyme Systems in Drosophila. Results and Problems in Cell Differentiation. W. J. Dickinson , D. T. Sullivan James B. BoydJames B. Boyd Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 51, Number 2Jun., 1976 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/409349 Views: 1Total views on this site Copyright 1976 Stony Brook Foundation, Inc.PDF download Crossref reports no articles citing this article.

Drosophila Gene-Enzyme Systems

The genetic analysis of morphological mutants of drosophila in the past years has led to a nearly complete catalog of specific genetic sites that control many features of the adult phenotype. An approach to understanding drosophila gene action has relied on studying mutations of genes for specific enzymes that affect subtle secondary characteristics of the enzyme, have little or no effect on enzymatic properties in vivo , and do not impair the viability of the mutant organism. Several different gene-enzyme systems in drosophila have been described and genetically characterized, thereby adding substantially to the understanding of genetic expression in eukaryotic cells. The chapter focuses on the specific properties of individual gene-enzyme systems that have been amenable to analysis and hold promise for additional investigation, and discusses the genetic nomenclature, specific gene-enzyme systems, dosage compensation of gene activity, genetic organization, genetic regulation of enzyme formation, and such. Emphasis on enzyme polymorphisms is given with the view that the results of these comparisons can often provide information on possible interactions of gene systems and products.

ISOZYMIC EVIDENCE BEARING ON THE ORIGIN OF NICOTIANA TABACUM L.

Isozyme patterns of plant organs and tissues are a direct reflection of particular genes that are operating at a given stage of growth and differentiation. Gene-enzyme systems affect survival and fitness in the course of evolution and consequently may provide useful information for studies of phylogenetic relationship. The application of isozyme patterns for biosystematics in plants has been reported in the recent literature (West and Garber, 1967; Sheen, 1970). The genus Nicotiana has been a favored material for studies on inheritance and evolution in higher plants. It comprises 64 presently recognized species (Smith, 1968), among which N. tabacum, an allopolyploid, is the only species cultivated around the world. The origin and evolution of N. tabacum has been deduced from morphological, ecological, genetic, and cytogenetic investigations. It is generally believed that interspecific hybridization, with subsequent amphiploidy as well as gene recombination, has played an important role in its evolution. However, N. tabacum is not found in nature (Goodspeed, 1954), particularly in the geographic area where the putative progenitor species overlap in their distribution. The origin of N. tabacum has, therefore, been a debatable subject for many years. In 1928 Clausen hypothesized that N. tabacum (N = 24) had originated from an interspecific hybrid between N. sylvestris (N = 12) and N. tomentosa (N = 12) after chromosome doubling. This hypothesis was later changed with regard to the progenitor species from the Tomentosae section. There are two currently recognized hypotheses regarding the origin of tobacco. Hypothesis I was proposed by Clausen (1932) and Kostoff (1938) who believed that N. tomentosiformis (N = 12) was one of the progenitors. In contrast, Goodspeed (1954) favored N. otophora (N = 12) (hypothesis II) as the closer relative of modern tobacco. Both hypotheses agreed that an ancestor of N. sylvestris was the other progenitor. Recently, Cameron (1965) added evidence that N. sylvestris contributed cytoplasm to the hybrid from which N. tabacum was evolved. The evolutionary process of N. tabacum may be clarified if synthesis of this species can be achieved through experimental hybridization and amphiploidy. Kostoff (1938) has conducted such experiments by backcrossing the F1 hybrid of N. sylvestris X N. tomentosiformis (2N = 24) first to N. sylvestris and then to N. tomentosiformis to reconstitute the respective genomes. He obtained two amphidiploids (2N = 48) which were taxonomically indistinguishable from N. tabacum and readily crossable with tobacco cultivars. However, some morphological features of the amphidiploids resembled the hybrids of a N. tabacum x (N. sylvestris x N. tomentosiformis) cross. Greenleaf (1942) produced similar amphidiploid from callus of the F1 hybrid. In contrast to Kostoff's amphidiploid which was self-fertile, the callus-induced one was completely female sterile but highly male fertile. Amphidiploids produced by colchicine treatments showed the same character of female sterility (D. U. Gerstel, pers. comm.). The present investigation was designed 1 Contribution from the Department of Agronomy, University of Kentucky, Lexington, Kentucky. Published with the approval of the Director as Paper No. (70-3-161) Journal series, Kentucky Agricultural Experiment Station.

Genetic studies of urease mutants in Neurospora crassa

Urease-defective mutants, genetic symbol ure, from Neurospora crassa were studied genetically with the use of known markers in crosses. A method was developed for rapid testing of urease activity in cultures from ascospore isolations. Two ure mutants, isolation numbers (9) and (47), respectively, were located in the right arm of linkage group V, approximately 30 crossover units from the centromere. The two ure mutants are at separate loci at a distance of approximately 3 c.o. units. They are separated by the gene am. Recombination between the two ure loci was studied using the closely linked markers am 1 (32213) and hist-1 (C91). A screening procedure was used to select for rare recombinant types from among random ascospores. A 1 ure +: ure − segregation of spore pairs within dissected asci was found in crosses between ure mutants (9) and (47). Mutants from the two ure loci complements to form urease-positive heterokaryons. The urease mutants are designated with a locus and an allele (isolation) numbers as ure-1 (9) and ure-2 (47), respectively, for future use. The results are discussed in relation to other complex gene-enzyme systems in Neurospora.

An Analysis of Gene-Enzyme Variability in Natural Populations of Drosophila melanogaster and D. simulans

Nine populations of D. melanogaster and two populations of D. simulans were analyzed for polymorphism in 10 gene-enzyme systems by the technique of gel electrophoresis. In the eight natural populations of D. melanogaster, an average of 54% of the enzymes were polymorphic, and the average heterozygosity was 22.7%. An experimental population of D. melanogaster, which has been maintained in a laboratory cage for 20 years, showed levels of polymorphism equivalent to those of natural populations. The D. simulans populations had much less variability. The possible factors involved in maintaining these polymorphisms are discussed.