bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection under assortative mating in mice
Authors: Sutherland T. M. , Biondini Patricia E. , Haverland L. H. 
Published: September 2009

1. Approximately 25000 mice have been produced over twelve generations of selection in nine lines. The experimental design involved a 3 × 3 factorial arrangement of direction of selection with mating system. The primary character measured was 6-week body weight.2. Consistently high phenotypic correlations between mates have been achieved, positive in the assortative lines, negative in the disassortative lines. Correlations were low and inconsistent in direction in the random-bred lines. These correlations have had very little, if any, effect in redistributing the genetic variance as estimated from the variance component analysis; the expected higher variances in the assortative lines and expected lower variances in the disassortative lines have not appeared, thus leaving heritability unaffected.3. Selection differentials likewise show no consistent advantage for the assortative lines, so that the progress from selection has been virtually identical in all three mating systems in each direction.4. Assortment of mates, either positively or negatively, for characters of even moderate heritability appears to have little influence on the outcome of selection. On the other hand, selection has been singularly effective in modifying the mean 6-week weight, with progress markedly greater in the downward direction; indeed it appears that the lower limit, may already have been approximately attained.5. Environmental effects operating in the various generations have affected all lines in remarkably consistent fashion.
Analysis of quantitative inheritance of body size in mice: V. Effects of small numbers of polygenes on similar genetic backgrounds
Authors: Chai C. K. 
Published: September 2009

Sublines carrying isolated polygenes determining body size, developed by selection and repeated backcrossing to theLGandSMstrains of mice, were inbred by full-sib matings with concomitant selection to study the inheritance of body size, using birth, weaning (28-day) and 60-day body weights as indices.Mean body weights in those sublines backcrossed toSMand selected for large body size were greater than in those selected for small body size, proving that the difference resulting from seven earlier generations of backcrossing and selection, although small, was genetic and could be fixed by inbreeding. The mean body weights of the sublines selected for small body size drifted upward despite downward selection, a phenomenon thought to be due to the pressure of natural selection outweighing that of artificial selection.In the sublines developed from backcrosses to theLGstrain, mice from lines selected for small body size attained a mean body weight greater than that of mice from lines selected for large body size and also than of the parentalLGstrain. These results were contrary to expectation and a genetic interpretation was offered.
Analysis of the genetic instability induced by nitrous acid in Schizosaccharomyces pombe
Authors: Loprieno N. , Abbondandolo A. , Bonatti S. , Guglielminetti R. 
Published: September 2009

A pedigree analysis of several cell-colony generations following a mutagenic treatment with nitrous acid has shown that in S. pombe a genetic instability is produced that replicates several times and produces a mutation in independent lines.It has been shown that the mutants isolated in the progeny of a mosaic colony all contain a genetic alteration that cannot be resolved by genetic analysis and therefore the mutations have occurred at the same genetic site. This finding is confirmed by interallelic complementation and phenotypic analyses.
Segregation of factors controlling fusion between plasmodia of the true slime mould Physarum polycephalum
Authors: Poulter R. T. M. , Dee Jennifer 
Published: September 2009

1. The occurrence of fusion between plasmodia produced from amoebal clones of P. polycephalum was studied.2. The occurrence of fusion was found to be strain-dependent and the factors responsible segregated in the progeny of a cross.3. The segregations found in crosses between several strains led to the conclusion that four alleles (f1–f4) of one gene f were controlling fusion in these strains.4. Fusion occurs only between plasmodia carrying identical f alleles, except in one class of results.5. A model accommodating all the results, including the ‘exceptional’ class, is proposed. It requires that the action of the f factors is to inhibit fusion between dissimilar strains rather than to promote fusion between identical strains. Certain physiological deductions from this model are discussed.6. The locus (mt) determining mating type of the amoebae is not concerned in plasmodial fusion and is unlinked to f.7. The rate of fusion between some pairs of strains is apparently influenced by modifying genes.8. It is suggested that, as a result of the operation of the f gene and of the previously described killing reaction, heterokaryons will occur rarely in natural populations of P. polycephalum.
Resistance ofEscherichia colito penicillins: III. AmpB, a locus affecting episomally and chromosomally mediated resistance to ampicillin and chloramphenicol
Authors: Nordström Kurt , Eriksson-Grennberg Kerstin G. , Boman Hans G. 
Published: September 2009

We have previously described strains ofEscherichia coliK12 resistant to D, L-ampicillin concentrations of 50 μg/ml (Eriksson-Grennberget al.1965; Bomanet al.1967). Such strains were assumed to be double mutants carrying the genesampAandampB. We here describe genetic steps which produce strains carrying only theampBgene. Determinations of resistance showed thatampAincreased the resistance provided byampA+by a factor of 10–15.AmpBincreased the resistance of bothampAandampA+by a factor of 2.R-factors were introduced into two sets of strains with all combinations ofampA,ampBand their wild type alleles.AmpAand the R-factors gave additive effects on resistance, whileampBdoubled the ampicillin resistance mediated byampAas well as by the R-factors.AmpBalso enhanced the chloramphenicol resistance of R-factor and of the wild type chromosomal genes. It is suggested thatampBresembles the modifying genes previously described and that R-factors can be useful for the identification of such genes.
The effects of population size and selection intensity in selection for a quantitative character inDrosophila: III. Analyses of the lines
Authors: Frankham R. , Jones L. P. , Barker J. S. F. 
Published: September 2009

1. In order to determine the nature of the genetic variation causing the response to selection in our lines (Joneset al.1968), various analyses were performed.2. There was no consistent change in heritability, estimated from half-sib correlation or from the phenotypic correlation between the bristle numbers of two abdominal segments, after 10 to 20 generations of selection.3. Realized heritabilities over the 10 generations subsequent to the heritability estimations were less than in the early generations but bore little relationship to the estimated values.4. Six lines contained recessive lethals with appreciable effects on bristle number as indicated by high variances, large regression on relaxation and large response to reverse selection.5. Reverse selection lines taken from the main lines at generation 40 indicated that genetic variation was still present in almost all of the lines. Only one line failed to respond to further forward or to reverse selection.6. The three highest lines were crossed in pairs and reselected. Two of the three possible crosses gave further response, exceeding the higher parent after one and three generations, but the other cross failed to pass the highest parent line.7. A combination of large gene effects, linkage, and gene interaction effects have been suggested as the cause of irregularities in the response of the lines. It has not been possible to determine the relative importance of these effects.
Drug sensitivity and mutability to drug resistance associated with the presence of an R factor
Authors: Yoshikawa Masanosuke 
Published: September 2009

SUMMARYStudies on the growth kinetics of R+and R−cultures ofEscherichia coliin the presence of nalidixic acid (NA), acriflavine (AF) and kanamycin (Kan) showed that each drug caused a decline in viability of both R+and R−cells for several hours. During further incubation the viability rose rapidly for the R+cultures, but either rose less rapidly (AF and Kan) or continued to decline (NA) for R−cultures. Distribution curves of the resistances of individual clones of R+and R−bacteria to atabrine, NA, AF and Kan suggested that the presence of an R factor in the host bacterium increased its mutation rate to resistance to these drugs: this would account for the more rapid growth rate of R+cells during the latter stages of incubation in their presence. The mutations causing increased resistance to NA and to Kan were located in the bacterial chromosome and not in theRfactor.
Interaction of a colicinogenic factor with a resistance factor and with the fertility factor F inEscherichia coliK-12
Authors: Cooper Pearl 
Published: September 2009

SUMMARYThe resistance (R)-factor R538–1drdof three F-like R-factors tested can cause the transfer of the non-transmissible ColV determinant fromE. coliV. The col factor, once transferred toE. coliK-12 strains, was shown to be related to the fertility factor, F, on the basis of entry exclusion and plasmid incompatibility. The col factor was found to recombine with R538–1drd, yielding a transmissible plasmid comprised of the col determinant and the sex factor of the R-factor, but not the resistance genes. The recombinant plasmid was found to be incompatible with both R538–1drdand F, and excluded the entry of R538–1drdbut not F.
Conditional induction ofλprophage inexrAmutants ofEscherichia coli
Authors: Donch J. J. , Green M. H. L. , Greenberg J. 
Published: September 2009

SUMMARYStrains ofEscherichia coliwhich contain the UV sensitivity geneexrA, repress UV induction ofλprophage in a novel manner. WhileexrA+strains can be induced by UV irradiation and express this induction in a 2 h period,exrAmutants delay the expression of induction for almost 4 h, and the induction maximum is approximately 10% of the wild-type value. The kinetics of the delayed induction and superinfection experiments indicate that the lifting of immunity and induction ofλprophage occur simultaneously.
Genetical evidence for diploidy in Phytophthora
Authors: Shaw David S. , Khaki Ikram A. 
Published: September 2009

SUMMARYA spontaneous mutant of Phytophthora drechsleri, resistant to p-fluorophenyl-alanine and two induced mutants resistant to chloramphenicol have been selected and analysed. The pattern of inheritance of the mutant phenotypes was identical and conformed to that expected in a diploid organism.
Chromosome transfer inPseudomonas aeruginosamediated by R factors
Authors: Stanisich Vilma A. , Holloway B. W. 
Published: September 2009

SUMMARYR factors present inPseudomonas aeruginosastrains of clinical origin can be transferred to other strains ofP. aeruginosaand may act to promote host chromosome transfer. In general, their properties are similar to those R factors in Enterobacteria. The different R factors studied vary with respect to transferability, transfer of specific resistance properties, repressibility, and ability to promote chromosome transfer.
The physiological control of gene action in theeyelessandeyegonemutants ofDrosophila melanogaster
Authors: Hunt David M. 
Published: September 2009

SUMMARYThe effect of dietary supplements of individuall-amino acids on the expression of theeyegoneandeyelessKmutants ofDrosophila melanogasterare compared. In both mutants, eye size is reduced by excess levels of tryptophan, phenylalanine and methionine, and in each case the effects are independent of metabolic competition for pyridoxal phosphate. A dietary interaction involving methionine and UNA can be demonstrated in theeyKstrain, but the mechanism of action of this amino acid is obscure. Tryptophan metabolism is examined in detail. Although both tryptamine and serotonin have significant effects, the action of tryptophan on eye development is largely independent of its metabolic products. Conversely, the effect of dietary supplements of certain catecholamines is consistent with the action of phenylalanine. The action of certain metabolic inhibitors provides additional support for the suggestion that the catecholamines have an important effect on morphogenesis in the eye imaginai disks. Eye development is also affected by increasing concentrations of γ-amino-butyric acid, and this, taken together with the effect of the catecholamines and indolalkylamines, suggests that physiological control of the action of the mutant genes on eye development involves a group of compounds characteristically associated with nervous tissue. Eye development in theeyKstrain may be influenced by the availability of acetyl CoA, which would be expected to affect acetylcholine biosynthesis. Possible mechanisms of action of the effective dietary treatments are discussed, together with a tentative hypothesis regarding the mode of action of the mutant genes on eye development.
The production and assay of segmental substitution lines in barley
Authors: Gale M. D. , Rees H. 
Published: September 2009

SUMMARYThe usual systems of assay using techniques of chromosome substitution demonstrated inDrosophilaand wheat are not applicable to barley (Hordeum vulgare). Chromosomal material for assay may, however, be substituted from one variety into another by using translocations to mark and restrict crossing over in the chromosomes to be transferred. This paper describes the isolation and assay of lines derived in this way.Seven substitution lines derived from the donor variety Maris Badger and the recipient variety Mars have been scored for quantitative characters in two field trials.The results indicate that variation in flowering time and other associated characters is largely determined by genes on chromosome 2 and that chromosome 4 is involved in the control of plant height.The feasibility of the technique as a method of assaying the contributions of chromosomes to qualitative characters by substitution in a diploid is discussed.
The microscopic appearance of waved-2 mouse hairs
Authors: McLaren Anne 
Published: September 2009

SUMMARYHairs from two stocks of homozygous waved-2 mice have been examined. The observations do not agree with a previous report, that the waving was due to a decrease in the proportion of guard hairs and an increase in the number of constrictions per hair, but are consistent with the view that it arises from a defect of keratinization.
Transduction mechanisms of bacteriophage ε15I. General properties of the system
Authors: Hedges R. W. 
Published: September 2009

SUMMARYBacteriophageεγis capable of transduction both by replacement of a genetic segment of the recipient by the homologous genetic material from the donor strain and by the formation of defective transducing particles capable of lysogenizing the recipient strain ofS. anatum.The isolation of strains carrying such prophages, which have incorporated the lactose or arabinose operons, is reported. Lysogenic strains, carrying both normal and defective transducing prophage, form high-frequency transducing lysates. Other strains, carrying only defective prophage, show evidence that the association of prophage genes and transduced materials is stable since the loss of one frequently entails loss of the other.
Spirochaete-mediated abnormal sex-ratio (SR) condition in Drosophila: A second virus associated with spirochaetes and its use in the study of the SR condition
Authors: Oishi Kugao 
Published: September 2009

SUMMARYA class of abnormal sex-ratio (SR) condition in Drosophila characterized by the elimination of male zygotes is caused by infection with maternally transmitted SR-spirochaetes. A given spirochaete strain, WSR, was shown to have an associated DNA virus, spv-2, in a latent condition. This virus is induced to multiply when another DNA virus, previously designated spv-1, infects WSR spirochaetes; spv-1 is normally associated with another strain of SR-spirochaetes, NSR, and is in a manifest state. Spv-2 infects and lyses NSR, thus eliminating spirochaetes from fly hosts which, in these experiments, were D. melanogaster.The elimination of WSR through lysis by spv-1 results in the ‘curing’ of the SR-condition in the host flies. However, the elimination of NSR by spv-2 does not lead to the immediate elimination of the SR-condition in the host. A hypothesis is presented in favour of the view that a substance, androcidin, is produced by SR-spirochaetes and that this substance is actually responsible for the death of male zygotes. NSR may produce a more potent androcidin than WSR.
A purine and pyrimidine requiring mutant ofDrosophila melanogaster
Authors: Vyse E. R. , Sang J. H. 
Published: September 2009

SUMMARYThe E.M.S.-induced auxotrophic mutant1308ofDrosophilais located between 13·7 and 21·0 on chromosome 1. Survival of larvae is possible if whole RNA is provided in the diet, and this is shown to be a requirement for a source of both purines and pyrimidines. A proportion of larvae will grow on pyrimidine nucleosides alone. Tests for utilization of bases and of precursors suggest that1308is a double mutant, and not a single mutation preventing the synthesis of a common precursor of purines and pyrimidines.
Phosphatases ofCoprinus lagopus: the conditions for their production and the genetics of the alkaline phosphatase
Authors: North Jane , Lewis D. 
Published: September 2009

SUMMARY1.Coprinus lagopusproduces two non-specific phosphatases: a constitutive acid phosphatase, and an alkaline phosphatase which is repressed during growth on media with a high inorganic phosphate concentration.2. The alkaline phosphatase is also repressed whenCoprinusis grown on an organic phosphate source; but if the acid phosphatase is selectively inhibited by fluoride the alkaline phosphatase is de-repressed and growth is comparable to that observed on an inorganic phosphate source.3. Alkaline phosphatase is not repressed in aerial mycelium or sporophores even when grown on high phosphate medium.4. Mutants altered in their capacity to synthesize alkaline phosphatase were selected from two compatible wild-type strains, H2 and H5.5. Mutants producing a higher level of alkaline phosphatase than wild-type (‘regulator’ mutants) fall into four (or possibly five) complementation groups. Assuming five separate genes, two pairs are linked; the remaining one is independent and on another chromosome.6. Mutants deficient in alkaline phosphatase synthesis fall into at least three groups. They were tested for linkage to ‘regulator’ loci but so far there is no evidence of this.
Phenotypic specificity of aneuploid states inAspergillus nidulans
Authors: Upshall A. 
Published: September 2009

SUMMARYHyperhaploid and hyperdiploid colonies ofAspergillus nidulans, disomic or trisomic for one or more chromosomes respectively, are abnormal in phenotype and somatically unstable. It has been shown for Glasgow strains that a different specific phenotype arises, depending upon which chromosome is additional (Pollard, Käfer & Johnston, 1968). This report extends this system and shows that irrespective of the residual genetic background of the isolate, the system of phenotypic specificity applies.
R-Factor elimination by thymine starvation
Authors: Pinney R. J. , Smith J. T. 
Published: September 2009

SUMMARYR-factor 1818, which is refractory to curing by acridines or ethidium bromide fromEscherichia coliK 12 andKlebsiella aerogenes418 hosts, was eliminated from thymineless mutants of these organisms under conditions of thymine starvation. Neither R-7268 nor R-TEM could be eliminated by this method. The concurrence of R-TEM with R-1818 inhibited the curing of R-1818, whereas R-7268 had no effect on R-1818 elimination
Genetic analysis of spontaneous half-sectored colonies ofSaccharomyces cerevisiae
Authors: Johnston J. R. 
Published: September 2009

SUMMARYGenetic analysis of spontaneous half-sectored colonies of a diploid strain homozygous forade2and heterozygous for linked markersaro1A,hom2,ade8 and trp4was undertaken. Some of these were due to an unexpectedly high rate ofade2reversion and others to a low incidence of haploid sectors. About 50% resulted from mitotic recombination. Only a few were due to mitotic crossing over alone, the majority resulted from non-reciprocal ‘conversion’, including recombination extending over two loosely-linked loci, and some colonies featured both mitotic crossing over and mitotic conversion. The latter indicate that negative interference operates for mitotic recombination. The rate of mitotic recombination forade8, calculated from the frequency of half-sectored colonies was 3·1 × 10−4per cell division.
Meiotic disjunction in mouse translocations and the determination of centromere position
Authors: Searle A. G. , Ford C. E. , Beechey C. V. 
Published: September 2009

SUMMARYIf heterozygotes for a reciprocal translocation are intercrossed, some of their viable balanced progeny result from the fusion of unbalanced gametes with complementary duplications and deficiencies of the translocated segments. Therefore, if one parent in such an intercross is homozygous for a genetic marker on one of the segments concerned, some homozygous offspring will be produced even if the other parent does not have the marker. The expected frequency of such exceptional offspring among live-born is one-sixth if the marker is on the distal (non-centromeric) side of the point of exchange and single chiasmata normally occur in each interstitial segment. Much lower frequencies are expected if the marker is on the centromeric side, since duplications and deficiencies of proximal segments occur only as a consequence of adjacent-2 disjunction, in which homologous centromeres proceed to the same pole. This is rarer than normal disjunction. Thus, by comparing the frequencies of offspring homozygous for markers on one or other side of the point of exchange, it is possible (i) to determine which marker is in the centromeric segment, (ii) to estimate the frequency of adjacent-2 disjunction, given information on the nature of meiotic configurations in the translocation concerned.By this method, it is shown that the frequency of adjacent-2 disjunction is similar in heterozygotes for mouse translocations(T5;18)26H, T(13; ?) 70HandT(14;17)264Ca, averaging 13%. Centromeres were located at theSdend of linkage group V (confirming previous findings), thefzend of XIII and the bg end of XIV.
The genetic control of anthocyanin biosynthesis by homoeologous chromosomes in wheat
Authors: Gale Michael D. , Flavell Richard B. 
Published: September 2009

SUMMARYColeoptile anthocyanin pigmentation in the hexaploid variety of wheat, Hope, is due to at least eight anthocyanins including four acylated forms. All are derivatives of either cyanidin or peonidin. Two homoeologous chromosomes, 7A and 7B, are involved in anthocyanin production. Both chromosomes carry genes that promote the synthesis of the same anthocyanins from flavonoid precursors. The roles of chromosomes 7A and 7B in anthocyanin biosynthesis and the consequences of interallelic interaction and dominance of possibly homoeologous loci are discussed.