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PubMed1976

Hereditary respiration deficiency in Saccharomycodes ludwigii.

Saccharomycodes ludwigii, supposed to be "petite-negative," gave rise to respiration-deficient mutants when acriflavine and ultraviolet irradiation, respectively, were applied to this yeast, strain IFO 1194. The frequency of such mutants was very low as compared with that in Saccharomyces cervisiae and other "petite-positive" yeasts. Cytochrome composition was characterized by spectrophotometry at the temperature of liquid nitrogen. The respiratory mutants examined contained cytochrome c unaltered in quality and quantity. Cytochrome b was often present only in small amounts though never absent, while cytochrome a + a3 was either present or absent. The respiratory mutants could form zygotes after conjugation with a wild-type culture of opposite mating type (alpha vs. a). The hybridization and segregation analysis of spore tetrads showed the inheritance of respiratory mutant character to be either Mendelian or non-Mendelian and similar to that of pet (nuclear) and rho- (cytoplasmic) mutants, respectively, in Saccharomyces cerevisiae.

Acriflavine↗
PubMed1985

Experimental allergic orchitis in mice. II. Association of disease susceptibility with the locus controlling Bordetella pertussis-induced sensitivity to histamine.

Susceptibility to the induction of murine autoimmune orchitis was found to be associated with the locus controlling Bordetella pertussis-induced sensitivity to the vasoactive amine, histamine. Only those inbred and H-2 congenic strains of mice possessing both the H-2d haplotype and the locus for susceptibility to B. pertussis-induced sensitivity to histamine developed autoimmune orchitis. In addition, segregation analysis of backcross generation mice also demonstrated a high degree of correlation between susceptibility both to disease and to histamine sensitization, which was indicative of additional multigene control. Pertussigen-histamine sensitization factor (P-HSF) was only effective in eliciting disease when it was administered on the same day, or within a period up to 6 days following sensitization with mouse testicular homogenate-emulsified in complete Freund's adjuvant. P-HSF induced sensitivity to histamine was not found to be associated with an increase in the vascular permeability of target tissue. Thus, B. pertussis-induced sensitivity to histamine appears to play a more crucial role during the sensitization phase of autoimmune orchitis induction, rather than at the inflammatory or effector phase of the disease.

Animals↗
PubMed1981

New chromosomal dysmorphic syndromes. 4. Trisomy 12p.

This is the report of two independent families in which a balanced maternal translocation led to trisomy 12 p in one of each their offspring. Evaluation of 21 further case reports indicates that this is a phenotypically well defined syndrome which leads to severe developmental retardation. It can be recognized by a characteristic combination of craniofacial anomalies which are summarized in a phantom picture. The gene sequences which produce the typical features in the trisomic state must be localized distally to band 12p12, which is the breakpoint in the partial trisomies. The specific craniofacial anomalies are not visibly modified by the length of the trisomic segment or additional small monosomies or trisomies of recipient chromosomes. However, the frequency and severity of organ malformations and the resulting probability of survival seem to decrease with increasing degrees of chromosomal imbalance. A cytogenetic classification of the 21 inherited translocations and a segregation analysis from the pedigree data was performed. For the different types of translocations the calculated risk figures are given.

Chromosomes, Human, 6-12 and X↗
PubMed1977

Residual family resemblance for PTC taste sensitivity.

Complex segregation analysis reveals no evidence for incomplete dominance, polygenic variation, or an effect of family environment on PTC sensitivity. Estimates of gene frequency and displacement from a phenotypic trichotomy agree closely with conventional values for the the dichotomy of tasters vs. nontasters.

Gene Frequency↗
PubMed1978

Genetic variation in the activity of the histidine catabolic enzymes between inbred strains of mice: a structural locus for a cytosol histidine aminotransferase isozyme (Hat-1).

Variation in activity of the main histidine catabolic enzymes (histidase, urocanase, and aminotransferase) has been surveyed using inbred strains of mice (C57BL, DBA, Peru, SM, and SWR). Some variation was found in the activity of all enzymes, but only in the case of cytosolic histidine aminotransferase was it greater than twofold (SM 3.3-fold greater than C57BL). The divergent strains for the activity of this enzyme were crossed and the F1's were backcrossed; the segregation analysis indicated a single locus with additively acting alleles (designated Hat-1: a allele SM, b allele C57BL). Cytosolic histidine aminotransferase differed in heat stability between SM and C57BL, indicating that Hat-1 is a structural locus. The conflict in the biochemical literature (Morris et al., 1973; Noguchi et al., 1976a,b) over the number and subcellular distribution of the histidine aminotransferase isozymes is partly resolved by the acquisition of a variant at the Hat-1 locus. Hat-1 affects the cytosolic form but not the mitochondrial form of the enzyme. Purification and analysis of the isozymes of histidine aminotransferase from livers of C57BL and SM mice will further clarify the situation.

Animals↗
PubMed1981

Genetic variation in erythrocyte NAD levels in the mouse and its effect on glyceraldehyde phosphate dehydrogenase activity and stability.

During a screening of inbred strains for enzyme variation in glycolysis, differences were found in glyceraldehyde phosphate dehydrogenase (GAPDH) activity between C57BL/6J and SM/J mice. Segregation analysis did not reveal unequivocal monogenic inheritance. Dialysis of hemolysates caused decay of enzyme activity, especially in C57BL animals, which could be prevented by the presence of NAD. This led to the finding that erythrocyte NAD levels were threefold higher in SM than C57BL animals and, although additively inherited, did not appear to be monogenic. This is comparable with but independent of the differences and effect of erythrocyte NADP levels on glucose-6 phosphate dehydrogenase activity reported by R. P. Erickson (1974) Biochem. Genet. 11:33] and emphasizes the range of mechanisms that can be involved in the genetic control of enzyme activity in mammalian systems.

Animals↗
PubMed1985

Aldehyde reductase isozymes in the mouse: evidence for two new loci and localization of Ahr-3 on chromosome 7.

Evidence is presented for two new forms of mouse liver and kidney aldehyde reductase activity (designated AHR-3 and AHR-4) resolved using cellulose acetate electrophoresis zymogram techniques and stained by glyceraldehyde and NADPH as substrate and coenzyme, respectively. Activity variants were observed for those isozymes among inbred strains of mice and used in a genetic analyses to support a proposal for two new genetic loci (Ahr-3 and Ah-4) which control the activity phenotype for these isozymes. Segregation analysis indicated that these loci are separately localized on the mouse genome, with Ahr-3 positioned on the distal end of chromosome 7. Liver AHR-2 (or hexonate dehydrogenase) exhibited no detectable phenotypic variation among the 44 inbred strains of mice examined. The AHR-3 and AHR-4 isozymes were readily distinguished from AHR-1 [or aldehyde reductase A2, described previously by Duley and Holmes (Biochem. Genet. 20:1067, 1982)], hexonate dehydrogenase (AHR-2), and alcohol dehydrogenase A2 in terms of their differential substrate, coenzyme, and inhibitor specificities.

Alcohol Oxidoreductases↗
PubMed1984

A regulatory locus, Hdc-e, determines the response of mouse kidney histidine decarboxylase to estrogen.

Levels of histidine decarboxylase (HDC; EC 4.1.1.22) activity in female mouse kidney are modulated by estrogen (administered as implanted pellets). In some inbred strains HDC activity is induced by estrogen, while in others the enzyme is repressed. Immunoprecipitation with an anti-fetal rat HDC antiserum has shown that induction and repression of HDC levels are due to changes in enzyme concentration. Segregation analysis has identified a single additively inherited regulatory locus, Hdc-e, which determines the response to estrogen. The allele Hdc-eb (C57BL/10) determines induction, and the allele Hdc-ed (DBA/2) determines repression. Preliminary evidence indicates cosegregation of Hdc-e alleles with alleles of another regulatory locus, Hdc-c (determining kidney HDC concentration), and therefore putative linkage of Hdc-e with the HDC gene complex on chromosome 2. This is the first report of a mammalian regulatory gene controlling two opposite mechanisms, induction and repression in response to a single effector.

Animals↗
PubMed1990

Biochemical and genetic studies on rabbit hemoglobin. II. Electrophoretic polymorphism of the alpha-chain.

A genetic polymorphism of rabbit (Oryctolagus cuniculus) hemoglobin alpha chain is demonstrated by means of acid starch gel electrophoresis. The polymorphism is not detected by isoelectric focusing and may be based upon neutral for neutral amino acid substitutions in accordance with previous findings by means of amino acid sequencing. Segregation analysis was performed on 15 matings with 49 offspring and confirmed the initial genetic hypothesis of three common codominant alleles at an autosomal locus. The calculated gene frequencies in a random sample of 86 unrelated individuals are HBA*1 = 0.73, HBA*2 = 0.22, and HBA*3 = 0.05.

Alleles↗
PubMed1991

Genetic polymorphism of sorbitol dehydrogenase in the brown hare and the distribution of the variation in central Europe.

A genetic polymorphism of sorbitol dehydrogenase (SDH; EC 1.1.1.14) for two allozymes is demonstrated in the brown hare (Lepus europaeus) by means of horizontal starch gel electrophoresis. Segregation analysis was performed in a sample of four matings with 12 offspring and confirmed the genetic hypothesis: two alleles at an autosomal locus. The calculated gene frequencies in the brown hare breed studied are Sdha = 0.712 and Sdhb = 0.288. The distribution of the polymorphism in free-ranging brown hare populations from Austria, Czechoslovakia, Hungary, and Poland is described.

Alleles↗
PubMed1990

Complexity at the mouse minor histocompatibility locus H-4.

The fine immunogenetics of the chromosome 7 mouse minor histocompatibility (H) locus H-4 was investigated. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted "helper" T cells (TH) specifically reactive with H-4 antigens were isolated as clones and were used as genetic probes for classical backcross segregation analysis. Results of a four point cross indicated that the H-4 locus was actually comprised of two genes, that have been designated H-46 and H-47. The former encodes antigens recognized by the TH and the latter encodes antigens recognized by the CTL. Moreover, these two genes could be separated from the gene pink-eyed dilution (p) which was found to be "sandwiched" between them. The functional significance of a minor H congenic strain differing by both TH-defined H-46 and CTL-defined H-47 was addressed using F1 complementation tests. Such studies indicated that immune responses against H-46 antigens was required for generation of H-47-specific CTL. Altogether, these results suggest selective presentation of different minor H gene products by class I or class II MHC proteins and that the minor H "locus" H-4 may have necessarily included both TH and CTL-defined genes because of requisite TH-CTL collaboration.

Animals↗
PubMed1975

On the mutation rate of neurofibromatosis.

A genetic study of 124 cases of neurofibromatosis was performed. The contingent of probands was mainly represented by a Russian population, most of the individuals being born in the European part of the RSFSR. Both parents of the probands were examined in only 58 cases, the proportion of sporadic cases in this group being 0.79, as compared to 0.77 for the whole group under study. The existing data evaluated by a direct method are not yet sufficient for a decisive estimation of the penetrance, which, however, cannot be under 80%. Segregation analysis of descendants from particular marriages showed a good correspondance to the hypothesis of Mendelian dominance (32 affected children out of 65). These results analyzed together with those obtained by other authors permit an inference on the full penetrance of neurofibromatosis. The genetic interpretation of sporadic cases as a result of new mutations is presented. The prevalence of neurofibromatosis among the 16-year-old youths was evaluated as 12.8 with 10-(5). This value is suggested to be an estimation of the incidence of the condition in the general population, the mutation rate evaluated by a direct method being equal to 4.4 with 10-(5) divided by 4.9 with 10-minus 5. The increased birth order of probands in sporadic cases (against the theoretical expectation) as well as increased paternal age (as compared with controls) were found to be statistically significant (P equals 0.004 and P equals 0.03, respectively) while the difference in maternal ages was statistically insignificant (P equals 0.008). No statistical relationship between sporadic cases and occupational exposure of parents to deleterious chemical and physical factors was found.

Adult↗
PubMed1995

A genetic study of idiopathic focal dystonias.

The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrance underlying focal dystonia.

Adult↗
PubMed1980

Genetic models of reading disability.

Test data collected on 133 reading-disabled (RD) children and their nuclear families who participated in the Colorado Family Reading Study were subjected to segregation analysis utilizing the technique of Elston and Yelverton (1975) for a continuous phenotypic measure. The possibility of genetic heterogeneity of RD was investigated by analyzing four subsets of data: all families, families with male probands, families with female probands, and families with severely affected probands. Furthermore, an analysis of the children's data was compared to that of all family members to investigate the possibility that the disorder may be manifested differently in adults. Results from the four subsets of data show that RD is etiologically heterogeneous. Compatibility with a major recessive gene for RD was demonstrated for families with female probands. Analyses of the children's data alone give results consistent with both environmental and genetic determination of RD.

Child↗
PubMed1987

High-frequency reactivation of X-linked genes in Chinese hamster X human hybrid cells.

Three genes on the human inactive X chromosome retained in the Chinese hamster X human hybrid cell line X8/6T2 have been reactivated using the demethylating agent, 5-azacytidine (5-aza-CR). Pulse-labeling and histochemical methods permitted detection and measurement of reactivation rates of the hypoxanthine phosphoribosyltransferase (Hpt) and glucose-6-phosphate dehydrogenase (G6pd) genes within 48 h of treatment. About 50% of the cells became active for these genes, which represents a reactivation rate some 30-fold greater than previously reported in similar systems. The phosphoglycerate kinase (Pgk) gene was not reactivated as frequently as the Hpt or G6pd genes. Segregation analysis of progeny of treated cells showed that enzyme-positive and enzyme-negative cells were produced in proportions supporting the notion that 5-aza-CR causes demethylation by replicative loss and that demethylation leads to reactivation.

Animals↗
PubMed1982

Structural and functional hemi- and dizygous Chinese hamster chromosome 2 gene loci in CHO cells.

Fourteen independent somatic cell hybrid clones made between diphtheria toxin (DT)-resistant mouse Cl1D cells and DT-sensitive Chinese hamster ovary (CHO) cells slowly segregated CHO chromosome. Concordant segregation analysis of electrophoretically resolvable Chinese hamster chromosome 2 gene products and CHO chromosomes 2 and Z2 (having q1-q24 deletion) in DT-selected and control hybrid subclones was conducted. Analysis revealed that loci for DT sensitivity and galactose-1-phosphate uridyltransferase could be regionally assigned to Chinese hamster chromosome 2q1-24 and were physically hemizygous in CHO cells. Enolase (ENO1), 6 phosphogluconate dehydrogenase (PGD), and phosphoglucomutase 1 (PGM1) were located outside the q1-24 region on Chinese hamster chromosome 2 and were dizygous in CHO cells. Functional dizygosity of ENO1, PGD, and PGM1 in CHO cells, as determined by the isolation of diploid heterozygous electrophoretic shift mutants following UV and EMS exposure, confirmed their location outside the Z2 deletion and indicated that the deletion did not result in the inactivation of adjacent loci. These results are discussed in relation to current theories on the basis for high frequency of drug-resistant autosomal recessive mutants in CHO cells and conservation of mammalian autosomal linkage groups.

Animals↗
PubMed1981

Enhancing the efficiency of DNA-mediated gene transfer in mammalian cells.

We have investigated several of the experimental factors that affect calcium phosphate-DNA-mediated gene transfer of thymidine kinase (tk) into mouse LM tk- Cl 1D cells using unfractionated DNA from both Chinese hamster ovary cells and L6 rat myoblasts. Increases in the length of exposure to DNA (24 h) and the expression time (48 h) before selection result in a 20-fold enhancement in the efficiency of transformation. These modifications yield frequencies up to 35 HATR colonies/20 microgram tk"NA/10(6) recipient cells. Exposure to dimethyl sulfoxide enhances transformation efficiencies slightly for short DNA exposure times, but has no effect when optimal DNA exposure times are used. Several other variations in our standard transformation protocol were also examined: these include the concentration and size of the DNA and exposure to low concentrations of the nonionic detergent, Tween-80. We have also isolated and characterized a subclone of Cl 1D that is a high-efficiency recipient for the tk+ marker. Segregation analysis reveals that the majority of the TK+ transformants derived from this subclone are stable, in contrast to those derived from the DL 1D parent. The combination of improved methodology and the high-efficiency recipient subclone permits DNA-mediated transformation for tk at frequencies on the order of 10(-4) transformants per recipient cell.

Animals↗
PubMed1994

Familial risk and genetic susceptibility for breast cancer.

Clinical observations suggest that breast cancer is occasionally inherited as an autosomal dominant disease in families. Epidemiologic studies consistently have shown that a history of breast cancer in a first-degree relative increases a woman's risk of breast cancer when compared with the general population. The risk is similar if a mother or sister is affected and is increased further if both are affected. The difficulty with such an observation is that in itself it does not clarify the nature of the true underlying risk factors which could be genetic or due to the aggregation of environmental risk factors in families. Complex segregation analysis of breast cancer aggregation in families suggests that breast cancer susceptibility is due to an autosomal dominant inheritance of one or more rare genes in a few families in which carriers have a high probability of developing the disease perhaps as great as 100 percent. Close linkage of a breast-cancer-susceptibility gene (BRCA1), between markers of the chromosomal region 17q12-q21 on the long arm of chromosome 17, with breast cancer recently has been reported. Families linked to BRCA1 were more likely to have early onset of breast cancer or have breast and ovarian cancer in the family. It is likely that other genes play a role in the unlinked breast-cancer families. Both the epidemiologic and genetic data suggest that breast cancer is a heterogeneous disease.

Age of Onset↗