bluuebunny/crossref_metadata_2025_split huggingface dataset:
A gene unlinked to mating-type affecting crossing between strains ofPhysarum polycephalum
Authors: Dee Jennifer 
Published: September 2009

SUMMARYTwo alleles of a gene (rac) unlinked to the mating-type locus (mt) have been identified in strains ofPhysarum polycephalumfrom different laboratories. Heterothallic strains differing inmtalleles cross more rapidly if they differ also in theirracalleles. The recovery of hybrid plasmodia from crosses between apogamic (mth) and heterothallic strains is more likely to be achieved if strains of differentracgenotype are used.
Evidence for transductional shortening of the plasmid obtained by recombination between the TOL catabolic plasmid and the R91 R plasmid
Authors: White G. P. , Dunn N. W. 
Published: September 2009

SUMMARYThe previously isolated plasmid pND3, arising from recombination between the TOL catabolic plasmid and the R plasmid R91, was transduced by pf16 inPseudomonas putida. Apparent transductional shortening was evident in 25% of the transduced pND3 plasmids. Transductants were isolated which had segregated the antibiotic resistance marker, transfer ability and some of the catabolic functions of the parent plasmid.
Drosophila alcohol dehydrogenase frequencies and temperature
Authors: Gionfriddo Maria A. , Vigue Charles L. 
Published: September 2009

SUMMARYD. melanogaster imagoes were collected weekly throughout the summer and early fall of 1976. Their Adh genotypes were determined by electrophoresis. The frequency of the Adh4 isoallele fluctuated throughout the period of study. Correlation coefficients assuming no delay, one week delay, two weeks' delay, three weeks' delay, and a four-week delay of the effect of temperature on the frequency of the Adh4 isoallele were insignificant. It was concluded that temperature alone may not be a selective factor but may be selective in combination with other environmental factors.
The expression of the gene asebia in the laboratory mouse: 2. Hair follicles
Authors: Josefowicz Wendy J. , Hardy Margaret H. 
Published: September 2009

SUMMARYMice homozygous for the asebia mutation (ab/ab) are char1acterized by defective sebaceous glands, a short sparse hair coat from 7 days and progressive alopecia. In addition, we have found that the initial hair follicle rudiments in the skin of these mice are able to differentiate into relatively normal anagen follicles which are often excessive in length and have minor abnormalities of the inner and outer root sheath components. The inner root sheath fails to form the typical transverse corrugations at the level of the sebaceous glands and its cells apparently remain, partially undegraded, plugging the hair canal and adhering to emerging hair shafts. Defects noted in the outer root sheath may be responsible for the failure of inner root sheath degradation. With increasing age, irregularities in hair cycle duration, loss of the originally parallel arrangement of hair follicles and further abnormalities of the individual follicular components are increasingly evident. Follicles in asebic mice have a tendency to form buds and branches which occasionally begin typical follicular differentiation. The consistent failure of the asebic follicles to pass normally through the catagen stage to the telogen stage results in long twisted follicles with abnormal and often loosely anchored hair clubs. The dermal papillae are often abnormal or absent from telogen follicles, while typical germ cells are not formed. Thus the lack of multiple hair follicles, the disorganization of follicles and the progressive alopecia observed in the asebic mice are accounted for. It is suggested that the altered dermal environment and outer root sheath abnormalities may be responsible for many of the follicular defects.
The expression of the gene asebia in the laboratory mouse: 3. Sebaceous glands
Authors: Josefowicz Wendy J. , Hardy Margaret H. 
Published: September 2009

SUMMARYContrary to what their name asebia implies, mice homozygous for the ab gene do possess actively secreting sebaceous glands which develop normally from the follicular outer root sheath, at 18 days post-conception. However, by the 20th day post-conception, these mice exhibit the abnormal sebaceous cytodifferentiation which remains typical of the asebic glands throughout life. Nests of outer root sheath cells below the sebaceous glands also undergo atypical sebaceous differentiation. The smooth membrane system and mitochondria, which appear to be responsible for the orderly accumulation of lipid droplets and sebum production in normal mice, become increasingly abnormal in asebic mice. Fewer lipid droplets form, the smooth endoplasmic reticulum becomes distorted and dilated, and the normal transformation of mitochondria does not occur. Atypical differentiation occurs randomly and ‘differentiated’ cells often degenerate within the asebic sebaceous glands. Of the larger specialized sebaceous-type glands studied, only the Meibomian glands are similarly affected by the asebia mutation, while the anal and preputial glands appear to undergo a more normal cytological differentiation. The abnormalities seen in the asebic sebaceous glands seem to be due to defective regulation of the synthetic or degenerative processes necessary for completion of normal sebum production. Both the defects of sebaceous glands and the unusual characteristics of the epidermis and hair follicles in asebic mice may be initiated by the abnormal underlying dermis or the apparently abnormal endocrine system.
Genetic variation between mice in their metabolism of coumarin and its derivatives
Authors: Lush I. E. , Andrews Kathryn M. 
Published: September 2009

SUMMARYAdult females from 19 strains of mice were injected with either coumarin or 7-ethoxycoumarin and the urinary excretion of the umbelliferone produced by the metabolism of these substances was measured. With the exception of C57L the strains fell into three classes as follows: high metabolizers (DBA/1 and DBA/2), medium metabolizers (CBA, 129/Rr, NZB and NZW) and low metabolizers (the other 12 strains). The difference in metabolizing ability between the medium group and the low group of strains was also evident when the 4-methyl derivatives of the same two substances were used. However with the 4-methyl derivatives there was no difference in metabolizing ability between the medium group and the high group. The results are interpreted as evidence that the gene Coh on chromosome 7 comprises two closely linked genes which determine cytochrome P-450 isozymes with different substrate specificities.
The effect of finite population size on models of linked overdominant loci
Authors: Avery P. J. 
Published: September 2009

SUMMARYModels of two linked overdominant loci in moderately large, but finite, populations are examined by looking at the variance-covariance matrix of the two gene frequencies and the linkage disequilibrium around stable deterministic equilibrium points. In particular, the effect of genetic drift is examined in cases where, in infinite populations, two stable equilibria with non-zero linkage disequilibrium,D, are maintained. Theoretical formulae are produced and checked by computer simulation. In general, the results show that unless the population size is very large indeed, genetic drift causes the values ofDto vary considerably about the equilibrium values and that for many models, where stable equilibria exist at non-zeroDvalues, a wide range of values ofDhave a high probability. Thus it is very difficult to draw conclusions about the selection regime by measuring Linkage disequilibrium in a finite population.
Genetic variation in plasma thyroxine levels and minimal metabolic rates of the mouse, Mus musculus
Authors: Stewart A. D. , Batty Jennifer , Harkiss G. D. 
Published: September 2009

SUMMARYA study of inbred strains of the mouse using competitive protein-binding techniques revealed significant strain variation in the total plasma thyroxine levels and in the plasma-free thyroxine index. Measurements of minimal metabolic rates also showed strain variation, but the positive correlation which might be expected between the plasma-free thyroxine index and the minimal metabolic rate did not obtain. Possible explanations are discussed.
Distribution of linkage disequilibrium with selection and finite population size
Authors: Avery P. J. , Hill W. G. 
Published: September 2009

SUMMARYThe effects of finite population size, occurring either as a bottleneck in a single generation followed by a large expansion or in all generations, are considered for models of two linked heterotic loci. Linkage is assumed to be tight because it is required if there is to be stable linkage disequilibrium,Dǂ 0, in infinitely large populations. (Dis the difference between gamete frequencies and the product of the gene frequencies.)If a substantial perturbation of frequencies occurs as a result of a bottleneck but the population is subsequently very large,Dmay take hundreds of generations to return to its stable point. In finite populations, the distribution ofDcan be ⋃-shaped, unimodal or bimodal. The correlation ofDin successive generations is higher with tight linkage and is little affected by selection or the size of the population.The utility of infinite population studies of linkage disequilibrium and its stable points is questioned, and considerable pessimism is expressed about the possibilities of distinguishing selection and sampling effects at linked loci.
Glutamyl-γ-methyl ester acts as a methionine analogue inEscherichia coli: analogue resistant mutants map at themetJandmetKloci
Authors: Kraus Jan , Soll Dieter , Brooks Low K. 
Published: September 2009

SUMMARYEscherichia coliK-12 mutants resistant to glutamyl-γ-methyl ester were isolated. A mutation leading to resistance of up to 1·4 mg/ml of the methionine analogue maps at min 63 and is 13% cotransducible withserAindicating an alteration in themetKgene. Another mutation leading to resistance to 3 mg/ml of the analogue and cross-resistance to other amino acid analogues maps at min 87. This mutation, which has the phenotype of MetJ−, is shown to be situated between theglpKandmetBgenes and thus indicates a different gene order from the published one.
Rate of segregation due to plasmid incompatibility
Authors: Cullum John , Broda Paul 
Published: September 2009

SUMMARYWe calculated the rates of segregation due to plasmid incompatibility under several simple models. A common feature of all the models that we considered is that incompatibility is caused by the inability of the segregation mechanism to distinguish between two incompatible plasmids.We measured the rate of segregation due to incompatibility of a pair of ColE1 derivatives under two conditions: (1) One plasmid was introduced into cells carrying the other by conjugation. (2) Cells carrying both plasmids were maintained by selection and then selection was released.Interpretation of the results was made more difficult by effects of the Plasmids on the host cell's growth rate. These experiments gave results in agreement with the predictions of a random pool replication model. Published results were also in reasonable agreement with this model.
Estimation of meiosis and sporulation efficiencies in the fission yeast by ascus analysis
Authors: Calleja G. B. , Zuker M. , Johnson Byron F. 
Published: September 2009

SUMMARYPopulations of linear asci are classified according to the number of spores in an ascus. The resultant five numerical classes are further classified into ten spatial classes according to the arrangement of the spores in an ascus and, by inference, into ten historical classes according to the number and origins of failures during the developmental process. An analysis of the observed frequencies of numerical classes allows derivation of the efficiencies of the first meiotic division, the second meiotic division and sporulation in a fission yeast. The analytical method may be useful in locating the site of action of sporulation inhibitors and in identifying meiosis mutants from sporulation mutants.
Variation among inbred strains of mice in adenosine 3′:5′ cyclic monophosphate levels of spermatozoa
Authors: Erickson Robert P. , Butley Martin S. , Martin Susan R. , Betlach Charles J. 
Published: September 2009

SUMMARYSpermatozoa from inbred strains of mice were found to vary significantly for levels of cyclic AMP when extractions were performed in a reproducible manner. The F1hybrid between high and low spermatozoal cAMP strains showed spermatozoal cAMP levels typical of the low strain. An analysis of spermatozoal cAMP in individual mice from the back-cross of the F1to the high strain suggested that alleles at more than one locus determine strain differences in spermatozoal cAMP. The major histocompatibility locus of mice,H-2, which had been found to have an effect on liver cAMP levels did not seem to affect spermatozoal cAMP levels.t-Alleles, which appear to alter fertilization rates by effects on motility, had no apparent affects on spermatozoal cAMP.
Additive effects of the genestabbyandcrinkledon tooth size in the mouse
Authors: Sofaer J. A. 
Published: September 2009

SUMMARYThe semi-dominantX-linked gene tabby (Ta) in the mouse and its recessive autosomal mimic crinkled (cr) produce the same mutant syndrome involving abnormalities of the hair, teeth and certain exocrine glands. Previous work has provided some indication of interaction between these loci in terms of vibrissa number. The results of the present study demonstrate that, for tooth size, mice doubly heterozygous for tabby and crinkled show a more extreme phenotype than either heterozygotes for tabby or crinkled alone.
Intramolecular amplification of the tetracycline resistance determinant of transposon Tn1771 inEscherichia coli
Authors: Schöffl F. , Pühler A. 
Published: September 2009

SUMMARYStrains ofEscherichia coliharbouring a conjugative plasmid that carries a transposon for tetracycline resistance (Tn1771) were found to be adaptable to very high tetracycline concentrations. The molecular analysis of plasmids isolated from strains with enhanced levels of tetracycline resistance revealed an intramolecular amplification of the resistance determinant of the tetracycline transposon.A model for the molecular structure of the transposon is presented, which suggests that there are three repetitive DNA segments on Tn1771. This accounts for the properties both of transposition and of gene amplification.
Allelism of methionine-sensitive mutants ofSchizosaccharomyces pombeto loci involved in adenine biosynthesis
Authors: Strauss Andre 
Published: September 2009

SUMMARYMethionine-sensitive mutants ofSchizosaccharomyces pombewere found to map at 16 loci,min1–min16, seven of which are allelic to knownadeloci involved in adenine biosynthesis. The mutantmin1–106was shown to be located within theade6locus by intragenic recombination analysis. Methionine sensitivity of these mutants is reversible by adenine supplementation and their pigmentation is similar to that of the correspondingademutants. We conclude, therefore, that theseminmutants are incompletely blocked in adenine biosynthesis. These observations further indicate that adenine biosynthesis inS. pombeis inhibited by methionine or a metabolite derived from it. For some otherminmutants showing reversibility of methionine sensitivity by leucine or proline, no allelism to knownleuorproloci was detected.
Characterization of fractional mutations inDrosophila: differential inhibition of complete and fractional mutations by inhibitors of repair synthesis
Authors: Mukherjee A. S. , Mandal S. K. 
Published: September 2009

SUMMARYThe ‘maxy’ technique was used for scoring the frequencies of whole body and fractional mutations in the progeny of males ofDrosophila melanogasterthat had been irradiated with 2000 R, irradiation being followed or preceded by treatment with caffeine or acriflavine. Three 2-day broods were used, and males irradiated without subsidiary chemical treatment were used as controls. Both chemicals whether given as post- or pre-treatment strongly reduced the frequencies of fractional mutants in all broods. The frequency of whole-body mutants was unaffected in the first two broods and suffered a moderate reduction in the third. These results are discussed in relation to the hypothesis that repair processes regulate the development of a primary lesion into either a whole-body or a fractional mutant and that the functioning of the repair enzymes depends on the state of maturity of the male germ cell.
Genetic structure of a natural population of Coriolus versicolor (L. ex Fr.) Quél.
Authors: Todd N. K. , Rayner A. D. M. 
Published: September 2009

SUMMARYExperiments were carried out to investigate genetic relationships within a population of Coriolus versicolor (a polyporaceous basidiomyceto causing white rot of wood) present in a birch stump. The population consisted of individual dikaryons occupying longitudinally continuous columns of decay separated from one another by narrow, dark, relatively undecayed interaction zones. These dikaryons were shown to be genetically homogeneous throughout their respective decay columns by dedikaryotization procedures. They were mutually antagonistic when paired in culture, but monokaryons derived from their fruit-bodies were interfertile. Experiments using synthesized dikaryons indicated that antagonism is inevitable between genetically distinct mycelia, but that the intensity of interaction diminishes with increased relatedness. Results of pairings between synthesized dikaryons and monokaryons varied according to the relatedness of the isolates. Antagonism invariably occurred when the monokaryon contained a nucleus differing from both nuclei in the dikaryon, but this did not necessarily prevent dikaryotization. Often in this situation dikaryotized sectors developed in the monokaryon visibly separated by zones of antagonism (‘tracks’). Where the monokaryon contained the same nucleus as one of the components of the dikaryon, antagonism usually occurred initially, but normally the colonies eventually fused.
Mechanism of infertility in t-complex mice
Authors: Archer J. R. , Self S. J. , Winchester B. G. 
Published: September 2009

SUMMARYSperm from mice heterozygous (t/+) for many t-lethal haplotypes show segregation distortion. More offspring inherit the t-haplotype than the normal wild haplotype. In contrast males heterozygous (tx/tv) for two t-lethal haplotypes are sterile although they produce normal-looking sperm. The experiments were undertaken to show whether sperm from tx/tv mice are the same as t-fertile sperm from t/+. Female albino mice were persuaded to mate first with coloured sterile tx/tv heterozygotes and then with normal white +/+ males. With the exception of one litter (from a t-heterozygous male which proved to have been misidentified) all the progeny were derived from the mating with the normal father. We conclude that t-bearing sperm from t-lethal (tx/tv) heterozygotes are inviable, and different from t-sperm in t/+ heterozygotes.
Herbicide-tolerant tobacco mutants selected in situ and recovered via regeneration from cell culture
Authors: Radin David N. , Carlson Peter S. 
Published: September 2009

SUMMARYThe herbicides Bentazone and Phenmedipharm kill the leaves of intact tobacco plants but do not affect callus cultures. Tolerant mutants were isolated by treating leaves of previously γ-irradiated haploid plants with herbicide then excising and culturing the green herbicide-resistant cell clones on the otherwise yellowed leaves. Among plants subsequently regenerated were a total of ten stable independently isolated mutants. Sexual crosses show these ten represent four Bentazone and two Phenmedipharm loci; all mutants were recessive to wild type.
Genetic analysis of the mutationFemale-lethalinDrosophila melanogaster
Authors: Marshall Terri , Whittle J. R. S. 
Published: September 2009

SUMMARYA genetic analysis was made of theFemale-lethal(Fl) locus ofDrosophila melanogaster. This is anX-linked mutation which causes lethality only in females. Other alleles do not complementFland are either lethal or sterile when homozygous in females. Complementation studies onFlalleles demonstrate that there is no simple ranking of these alleles in terms of severity of phenotypic effect. Dosage manipulation ofFlalleles indicates that the sex-specificity is not a consequence of gene dosage effects. Viability studies on males carryingFlalleles show thatFlalleles have no effect on viability regardless of the presence or absence of aYchromosome. TheFllocus is therefore sex-specific. The hypothesis thatFl+ is involved in the establishment of imaginal phenotypic sex cannot be substantiated on the basis of experiments utilizing sex-change mutations.
A test for the rare male mating advantage in coisogenic strains of Drosophila melanogaster
Authors: Markow Therese A. 
Published: September 2009

SUMMARYExperiments were carried out to see if rare male mating advantage could be detected when males differ at only one locus. The eye colour mutant sepia was inserted into a strain of Drosophila melanogaster homozygous for a first, second, and third chromosome from the Canton-S strain. Tests for the rare male advantage were conducted using ratios of 4:1, 1:1, and 1:4 of the coisogenic wild-type and sepia males. No deviations from expected types of matings were observed. The results are discussed with respect to possible conditions necessary for the rare male effect to occur.
Diapause in the gypsy moth: environment-specific mode of inheritance
Authors: Lynch Carol Becker , Hoy Marjorie A. 
Published: September 2009

SUMMARYPreliminary investigation of the genetic basis of diapause in the gypsy moth, Lymantria dispar, involved a comparison of reciprocal crosses between wild-type moths and a selectively bred ‘non-diapause’ strain with the parental stocks, where half of the eggs resulting from each of the four mating types were exposed to one month of chill at 5 °C. The presence of chill dramatically altered the phenotypic expression of diapause-dependent characteristics. Early hatching was completely recessive in unchilled eggs, while hatching time was intermediate in chilled eggs, and there was no difference between reciprocal hybrids. Proportion of eggs hatching and, therefore, number of larvae produced was also influenced by chill. Unchilled hybrids did not differ substantially from wild-type eggs, while chilled hybrids were closer to the performance of the selected line. In this case, a significant reciprocal difference indicated some involvement of sex-linkage in the inheritance of diapause.
Inheritance and morphology of exencephaly, a neonatal lethal recessive with partial penetrance, in the house mouse
Authors: Wallace Margaret E. , Knights P. J. , Anderson Janice R. 
Published: September 2009

SUMMARYAn inherited exencephaly in the mouse is described, using embryos at 11–17 days gestation. The cephalic portion of the neural tube remains open on the dorsal surface, the bony vault of the brain fails to develop, and the tissues of the brain are exposed; the development of these tissues, which is somewhat variable, is described. There is strong evidence that the condition is due to a single recessive gene, xn, with full viability until birth. Penetrance is twice as high in females as in males, and it varies overall according to the genetic milieu studied, from 33% to 84%. These features, and the absence of pleiotropic effects and of genetic evidence of associated chromosomal anomalies, make its inheritance different from that of exencephalies so far described.