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The Genetical Society of Great Britain THE GENETICAL SOCIETY OF GREAT BRITAIN ABSTRACTS of Papers presented at the HUNDRED AND SEVENTY-NINTH MEETING of the Society held on 14th and 15th NOVEMBER 1975 in UNIVERSITY COLLEGE, LONDON. INTERSPECIES TRANSFER OF MITOCHONDRIA OF PARAMECIUM AURELIA G. H. BEALE and J. K. C. KNOWLES Institute of AnimalGenetics,Edinburgh Thetechnique of microinjection has been used to transfer mitochondria between in- dividuals belonging to different species of Paramecium aurelia, isolated by natural genetic barriers. Mitochondria from three species (denoted nos. 1, 5 and 7) were injected into paramecia belonging to each. Erythromycin-resistant paramecia were used as donors and sensitive cells as recipients, thus making possible a selection of donor mitochondria in the recipients, by adding erythromycin to the medium. Mitochondria from species 1 and 5 could be readily transferred and maintained in all three species, but species 7 mitochondria could be maintained in species 7 cells only. Further- more, species I mitochondria could be established in species 1 cells more readily than in species 5. Hence there are minor differences between species I and 5 mitochondria, and a more pronounced difference between these two and species 7 mitochondria. Study of the transferability of mitochondria from "hybrid" cells, i.e. those containing nuclei of one species and mitochondria from another, gave evidence indicating that the "compatibility" of mitochondria is mainly under the control of the nuclear genome. CELLSURVIVAL AND CHROMOSOME DAMAGE IN ATAXIA TELANGIECTASIA FOLLOWING X-IRRADIATION A. M. R. TAYLOR, J. A. METCALFE, J. M. OXFORD and C. F. ARLETT Department ofCancer Studies,Medical School, University ofBirmingham and M.R.C.Cell Mutation Unit, University of Sussex, Brighton Ataxiatelangiectasia (AT) is an autosomal recessive syndrome in which a main charac- teristic is an enhanced level of malignant disease. (Kersey, Spector and Good. mt. J. Cancer, 12, 333-347, 1973). Patients given radiotherapy have shown an increased sensitivity to ionising radiation (Cunliffe, Mann, Cameron, Roberts and Ward. Brit. J. Radiology, 48, 374-376, 1975). Cell survival experiments on skin fibroblasts from these patients show that this radio- sensitivity is reflected at the cellular level, in all six cases we have studied. Cells from a heterozygote for AT showed normal levels of sensitivity. Investigations into the radiosensitivity of chromosomes of blood lymphocytes from normal controls and AT individuals have revealed: (1) Important differences between these two genotypes following irradiation at the beginning of both Gl and G2; and, (2) Possible anomalies in the accepted classification of chromosome and chromatid type damage induced by irradiation in early Gl and G2 respectively. AHAPLOIDISATION TECHNIQUE FOR COPRINUS LAGOPUS JANE NORTH Department of Biological Sciences, Cityof London Polytechnic Although stable vegetative diploid strains of Coprinus lagopus are easily selected from common-A heterokaryons, they rarely haploidise even under selective pressure (Casselton, 36/2—s 283 284 GENETICALSOCIETY OF GREAT BRITAIN Genetical Research 6, 190-208, 1965). The antibiotic griseofulvin is commonly used against dermatophytes and is known to inhibit mitosis in Basidiobolus ranarum by interfering with the spindle apparatus (Gull and Trinci, Arch, Microbial. 95,57-65, 1974). When diploid strains of C. lagopus are grown on medium containing 20 jig/mi griseofulvin, growth is inhibited by 70-80 per cent. More rapidly growing sectors arise after a few days; most when tested appear to be haploids with recombinant genomes. Some sectors remain disomic for the B mating-type locus and may be mitotic recombinants. THEDOMINANCE INDEX AND IMMUNOGENETIC (IR-GENE) SYSTEMS A. EBRINGER, N. DEACON and C. YOUNG Immunology Unit, Department of Biochemistry, Queen Elizabeth College, London Antigensinjected into different inbred strains of the same species, frequently produce high antibody responses in some strains and low antibody responses in other strains of animals. It has been suggested that this indicates the presence of dominant immune response (IR) genes in high responder animals and their absence in low responder animals (Benacerraf and McDevitt, Science 175, 273, 1972). Genetic degrees of dominance can readily be calculated when examining quantitative phenotypic traits confined to one locus and excluding the effects of pleiotropic and epistatic genes. The degree of dominance (d) was calculated using Fisher's formula (Fisher, Trans. Roy. Soc. Edin. 52, 399, 1918), where, d= Aa—aa —l (AA—aa) and which takes the value of + 1 for complete dominance, —1for complete recessivity and the value of zero for no dominance. In reviewing 875 Fl hybrid animals, obtained from 47 different immunogenetic systems, the degree of dominance (d) was found to be: d =—00284±0Ol48(mean±S.E.) which is close to a value of zero, thus indicating no genetic influence of one allelic JR-gene upon the other, and this lack of dominance is statistically significant (= 2343,p <0.01). Furthermore, Fl back crosses to parental strains give 50 per cent parental response and 50 per cent Fl hybrid response in the backcross progeny. It is suggested that in immunogenetic systems, both alleles are expressed as co-dominant genes. THEtamA LOCUS IN ASPERGILLUS N!DULANS J. A. PATEMAN and J. R. KINGHORN Deportment of Genetics, University of Glasgow, Glasgow Mutantsdesignated tamArl 19 etc., formerly amrB (Kinghorn and Patema, Heredity, 31, 427, 1973) have been described which are resistant to the toxic analogues thiourea, aspartic hydroxamate, methylammonium and chlorate with L-alanine as the sole nitrogen source. The resistance of tamAr mutants is correlated with partially repressed levels of some enzyme and transport systems regulated by ammonium. Furthermore, lamAr mutants have low NADP-glutamate dehydrogenase activity and also efflux ammonium under certain con- ditions. This mutant isolation method also generated partially repressed mutants at the areA locus (Arst and Cove, Molec. gen. Genet., 126, 111-141, 1973). A fully repressed allele of tamA has been made (tamAt50). It is unable to utilise a number of inorganic and organic nitrogen sources and grows normally only on ammonium. A revertant of tamA' was selected on the basis of sensitivity to the toxic analogues in the presence of ammonium. This derepressed allele, designated tamA4l, is insensitive to am- monium control of a number of ammonium repressible systems. GENETICAL SOCIETY OF GREAT BRITAIN 285 The properties of the various tamA alleles establish that tamA is a regulatory gene involved in the control of nitrogen and/or carbon metabolism in A. nidulans. THENEWBORN SCREENING BLOOD SAMPLE: A VALUABLE SOURCE OF GENETIC DATA IN MAN P. S. HARPER and L. K. BORYSEWICZ Section of Medical Genetics, Department of Medicine, Welsh National School of Medicine, Cardiff Inall regions of Britain and in most of continental Europe a capillary blood sample dried on filter paper is taken from all newborn infants for the detection of phenylketonuria. This sample represents a potentially valuable source of population data on polymorphic genetic markers, and a study has been made in Wales to assess the feasibility of using it to obtain population frequencies for blood group and red cell enzyme systems. The results for the ABO blood group system and for the enzymes PGM 1 and AK show close correspondence with phenotype frequencies obtained from conventional samples and methods; the sample is less suitable for some other loci which may not be fully expressed in the newborn period. The application of this approach to studies of genetic variation between and within popu- lations, and to the prospective study of the selective advantage of genetic polymorphic systems, will be discussed. GENETICHETEROGENEITY AND VARIATION OF ENZYME ACTIVITIES IN PRIMARY AND TRANSFORMED CHINESE HAMSTER CELL LINES J. M. CLARK and J. A. PATEMAN Institute of Genetics, University of Glasgow, Glasgow Gil Sf5, Scotland Theactivities of nine enzymes have been studied in cultured Chinese hamster Kupifer cells. The Kupifer cell population in liver provides a source of homogeneous cells which express "differentiated" functions in culture. Isolated Kupifer cells from three adult, female sibs were used to initiate 130 cell lines, each originating from a single Kupifer cell. The following enzyme activities were studied: peroxidase, catalase, fl-glucuronidase, arginase, haem oxygenase, alcohol dehydrogenase, lactate dehydrogenase, isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase. Each enzyme demonstrated considerable variation in activity between cell lines. In all cell lines, enzyme activities dropped below the initial level and maintained a minimum activity for approximately 80 cell doublings. Hetero- geneity of enzyme activities was not paralleled by karyotypic variation. Transformation of cultured adult Kupifer cell with Simian Virus 40 resulted in the loss of "differentiated" functions, and all enzyme activities, with the exception of fl-glucuronidase, fell to a fraction of those observed in primary adult cell lines. Unlike cultured Kupifer cells from adults, cultured foetal Kupifer cells exhibited many of the properties of transformed adult Kupifer cells. The observation of a high correlation between certain enzyme activities in cultured adult cells suggests the possibility of a mechanism which controls the activities of two or more unrelated enzymes. These correlations are maintained in cultured foetal cells
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