bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inheritance of Scottish-type resistance to warfarin in the Norway rat
Authors: Greaves J. H. , Ayres P. B. 
Published: September 2009

SUMMARYThe inheritance of resistance to the rodenticide, warfarin, in the Norway rat, Rattus norvegicus, derived from a wild rat population in Scotland was studied in the backcross, intercross and testcross. The resistance was found to be due to a major gene with about the same map position in Linkage Group I as the warfarin-resistance gene, Rw2, which occurs in the wild rat population in Wales. In heterozygotes, the Scottish resistance gene, unlike the Welsh gene, is incompletely penetrant in expression, though the penetrance was found to increase markedly in response to selection. Differences between the Scottish and Welsh types of resistance suggest that the two resistance genes are allelic.
Parental age and recombination frequency in the house mouse
Authors: Wallace Margaret E. , MacSwiney Felicity J. , Edwards R. G. 
Published: September 2009

SUMMARYThe relationship between parental age and recombination frequency in the offspring of mice has been studied using backcrosses to heterozygous males or females. The mice were allowed to breed until they became infertile. Data for several chromosomes were analysed, mostly from a stock carrying five markers covering approximately three-quarters of the length of chromosome 2.Analyses of two-point recombination ratios or of multi-point interference ratios revealed no consistent age-related heterogeneity in offspring of male or female heterozygotes. A significant age-related heterogeneity was detected in the offspring of female heterozygotes but not of males, when the number of offspring with no detectable recombination was compared to those with one or more. This difference between the sexes could be related to earlier cytological observations on chiasma frequency in oocytes and spermatocytes. The significance of these findings for the analysis of follicular growth in mammals and in the origin of human trisomic conditions is discussed.
New results on the genetic characteristics of the Far East race of Drosophila melanogaster
Authors: David J. , Bocquet C. , Pla E. 
Published: September 2009

SUMMARYRecently collected strains from Malay peninsula, Taïwan and Japan proved to be similar to previously studied Japanese strains kept for long time under laboratory conditions. It is therefore possible to speak of a Far East race, characterized by slow growth, very high fresh weight and small ovariole number. High heterogeneity between laboratory strains founded from wild caught flies seems also typical. Among the three traits studied, a positive genetic correlation was observed only between duration of development and adult weight. No correlations were found between biometrical traits and the latitude of strain origin. The problem of the origin of the Far East race is discussed.
Distribution of crossing-over in mouse chromosomes
Authors: Lyon Mary F. 
Published: September 2009

SUMMARYIn devising maps of the positions of gene loci along chromosomes, by measurements of crossing-over, it is usual to assume that the chiasmata which give rise to the crossing-over are randomly located, unless there is evidence to the contrary. If chiasmata are in fact preferentially located at certain points or regions this not only affects mapping, but also is of interest for population genetics since it may favour the development during evolution of blocks of genes relatively undisturbed by crossing-over. Preferential localization of chiasmata is well known in a number of disparate organisms (Darlington 1965; John & Lewis, 1965), but has so far been little studied in mammals. Evidence is presented suggesting tha chiasmata are in fact non-randomly located in certain chromosomes of the mouse.
Characterization of the new osmotic mutants (os) which originated during genetic transformation inNeurospora crassa
Authors: Mishra N. C. 
Published: September 2009

SUMMARYInositol independent (inl+) strains were obtained either as transformants following treatment of the inositol requiring (inl) strains ofNeurospora crassawith the wild-type DNA or as revertants without any DNA treatment. A significant number of the inositol-independent transformants were also found to have acquired additional mutations called osmotics (os) which made them unable to grow on 1 m-NaCl medium. None of the inositol-independent revertants were found to possess such osmotic mutations and their growth remained unaffected by the presence of NaCl. Many of the osmotic mutants described here were found to be new alleles of the previously knownos–1mutation on the linkage group I ofNeurospora crassa. The remainder were found to map at two new genetic loci designated asos-6andos-7; these loci were found to be closely linked toos–1. Among the new osmotic mutants onlyos-1andos-6mutants showed intragenic complementation. The mechanism of DNA-induced mutation during transformation is discussed.
Superinfection inhibition by prophage B3 of some R plasmids inPseudomonas aeruginosa
Authors: Krishnapillai V. 
Published: September 2009

SUMMARYThe prophage of the phage B3 ofP. aeruginosaexhibits superinfection inhibition towards certain R plasmids such as R18-1 or R18-3 as shown by a severe depression (c. 10−6) in the conjugal transfer of these plasmids into B3 lysogens. The transfer of other R plasmids into such lysogens and the transfer of R18-1 or R18-3 into bacteria lysogenic for unrelated phages was unimpaired. R18-1 or R18-3 was non-transducible into B3 lysogens although transducible into non-lysogens. The interaction appeared to be reciprocally expressed since B3 lysogenization of bacteria R+for R18-1 or R18-3 was also reduced. Consistent with the failure of co-existence of the prophage and the plasmids was the observation that when the transconjugants from the cross R18-1 donor ×B3 lysogenic recipients were tested, transfer-deficient plasmid derivatives were encountered (about 40%). Other transconjugants were cured of prophage, or carried mutant B3 prophage with lytic, lysogenization or superinfection inhibition functions impaired.
Factors affecting the observed number of young resulting from adjacent-2 disjunction in mice carrying a translocation
Authors: Lyon Mary F. , Glenister P. H. 
Published: September 2009

SUMMARYThe frequency of adjacent-2 disjunction in mice carrying the reciprocal translocation T(9; 17)138Ca was studied by mating together animals heterozygous for the translocation and carrying different recessive marker genes, usingTtfor chromosome 17 andcwcwfor chromosome 9. The proportion of marked young arising from adjacent-2 disjunction varied according to the markers carried in the two parents. When the female carriedTtthe frequencies of marked young were always higher than when non-Tfemales were used, and whenTtandcwcwwere carried in the same parent there was a shortage of marked young obtaining both copies of the proximal region of chromosome 17 from the father. Both these effects were regarded as probably another example of the phenomenon discovered by Johnson, of inviability of young lacking a maternal homologue of a certain region of chromosome 17. There were other variations in frequency of marked young, among crosses using non-Tfemales, which may have been due to differences in transmission ratio of male gametes carrying varioust-haplotypes or to true variations in frequency of adjacent-2 disjunction.
The effect of random selection coefficients on populations of finite size – some particular models
Authors: Avery P. J. 
Published: September 2009

SUMMARYThe model of random selection coefficients is considered in the context of a finite population of diploids. The selection coefficients of the homozygotes are allowed to vary with equal variance while the fitness of the heterozygote is kept fixed. Steady-state solutions are found in the case of equal two-way mutation rates with particular reference to the expected heterozygosity. Increasing the variance of the selection coefficients of the homozygotes is found to uniformly increase the heterozygosity for all values of the average selection coefficients and its effect is largest when the selection coefficients of the homozygotes are fully correlated. The fate of mutant genes is also considered in the case of random selection coefficients by looking at the probability of ultimate fixation and the mean times to fixation and extinction. The errors in previous calculations (e.g. Kimura, 1954; Ohta, 1972) are pointed out. It is found that a small average heterozygote advantage together with a reasonable degree of variance in the coefficients can cause an unexpectedly large amount of heterozygosity to be maintained. It is also seen that probabilities of fixation and mean times to boundaries are usually increased by increasing the variance showing that it in fact helps to keep the population heterozygous for much longer than the non-random case. This is in contradiction to some conclusions of Karlin & Levikson (1974) because their haploid results are not easily extendable to the consideration of this sort of diploid model.
On the fixation probability of a gene under random fluctuations in selection intensities in small populations
Authors: Narain Prem , Pollak Edward 
Published: September 2009

SUMMARYA population withNmonoecious individuals, and having two alleles, is considered. The problem of calculating the fixation probability of a particular allele under random fluctuation of selection intensities is re-examined, employing finite Markov chain methods. An approximate but general expression for this probability is obtained and the results obtained by previous workers are shown to be special cases of this result.
Resistance to meiotic drive at theMDlocus in an Indian wild population ofAedes aegypti
Authors: Suguna S. G. , Wood R. J. , Curtis C. F. , Whitelaw A. , Kazmi S. J. 
Published: September 2009

SUMMARYFemales from an Indian wild population ofAedes aegyptiwere crossed to males carrying the sex ratio distorter factorMDwhich shows meiotic drive. Progenies from F1males were tested for sex ratio distortion, i.e. the chromosomes from the wild females were screened for their resistance to the action ofMD. The distribution of sex ratio in the progenies of different F1males indicated a polymorphism in the wild population for resistant and sensitive variants of theXchromosome. Seven discrete categories ofXappear to exist, associated with sex ratios ranging from 50% ♀ to less than 1·25% ♀. The overall level of resistance varied slightly but significantly in different parts of a town. The results are discussed in relation to the use of sex ratio distortion for genetic control of mosquitoes.
Genetical and embryological comparison of two mutations which cause foetal blebs in mice
Authors: Center Elizabeth M. 
Published: September 2009

SUMMARYMutants with abnormalities which were the consequence of the formation of haematomas during gestation were designated as ‘foetal haematomata’ (fh). Thefhhomozygotes were found to be morphologically and embryologically very similar to myelencephalic bleb (my) mice. It was also found, however, that thefhandmymutants were separate genetic entities due to two independently segregating recessive genes.
Long-term storage of mouse embryos at —196 °C: the effect of background radiation
Authors: Whittingham D. G. , Lyon Mary F. , Glenister P. H. 
Published: September 2009

SUMMARYIn order to test the feasibility of preservation, of genetic stocks of mice by storage in liquid nitrogen, mouse embryos at the 8-cell stage, were frozen and stored in liquid nitrogen at – 196 °C under increased radiation exposures of 1·8×, 9× and 84× background levels for periods of 6–8 months, 10–12 and 27–29 months, the 1·8 × level being regarded as a control. Their survival rates to the blastocyst stage, and after transfer to recipient females, to foetal or liveborn stages were then compared with those of unfrozen or short term frozen control embryos. The freezing processper secaused a marked loss of viability, in comparison with the unfrozen controls, but at the 1·8× radiation level there was then no further loss in viability even at the longest storage time (27–29 months). Similarly, at the 9× radiation level there was no loss of viability during storage up to 29 months, but at the 84× level the proportions of implanted embryos and live foetuses were slightly reduced. It was not clear if this was a true effect of radiation, since it was not related to time of storage. Considering all groups, about 20–30% of the embryos originally frozen were recovered as foetuses or liveborn young. It is concluded that the preservation of genetic stocks by storage in liquid nitrogen is a feasible proposition.
A new allele at the patch locus in the mouse
Authors: Truslove Gillian M. 
Published: September 2009

SUMMARYEvidence is presented for the existence of a new allele at the patch locus called patch-extended (symbol Phe). Crosses of Phe with Ph, Wv and Rw produce double heterozygotes that are different from those resulting from the original patch allele. Besides the different coat colour in these mice, all the Wv + / + Phe animals that were tested resembled Wv + / Wv + and proved to be sterile. However, the two patch alleles interact to produce a split-face phenotype which resembles the presumed Ph/Ph.
Unifactorial inheritance of warfarin resistance in Rattus norvegicus from Denmark
Authors: Greaves J. H. , Ayres P. B. 
Published: September 2009

SUMMARYWild populations of the Norway rat, Rattus norvegicus, in Jutland have been known to be resistant to the anticoagulant rodenticide warfarin since 1962. The inheritance of the resistance was investigated in the F1, backcross and intercross. The results are consistent with the resistance being due to a major gene at the Rw locus. Resistant homozygotes, heterozygotes and susceptible homozygotes appeared to be distinguishable experimentally on the basis of differences in their susceptibility to vitamin K deficiency. The results are discussed in relation to previous studies of the inheritance of warfarin resistance in rats.
The detection, in unordered octads, of 6+:2mand 2+:6mratios with postmeiotic segregation, and of aberrant 4:4s, and their use in corresponding-site interference studies
Authors: Ghikas Aglaia , Lamb B. C. 
Published: September 2009

SUMMARYSystems for the detection of postmeiotic segregation in unordered octads are described for 4:4(2), 6:2(2), 2:6(2), 5:3(3), 3:5(3) and 4:4(4) segregations, where the number in parentheses is the number of pairs of non-identical sister-spores. Linkage relations, centromere distances and phenotypic detectability of suitable combinations of markers for initial selective identification of such segregations, and subsequent confirmation tests, are discussed; correction formulae are given to allow for non-detection of certain classes in particular circumstances. Using one such system inAscobolus immersus, we detected 4:4(2), 6:2(2) and 2:6(2) segregations at thew-78 site: 2:6(2)swere previously unknown. Initial visual detection in this system was from octad phenotype ratios forw-78 (white ascospore) andgr-3 (granular ascospore pigmentation), with mating type and parafluorophenylalanine resistance as confirmatory markers after germination. Corresponding-site interference for wider ratio and – for the first time – narrower ratio unique classes was determined: it was moderately positive or moderately negative, depending on the cross and segregation class involved.
Genetic analysis of nystatin-resistant mutants ofSaccharomyces cerevisiae
Authors: Karunakaran V. , Johnston J. R. 
Published: September 2009

SUMMARYPrimary genes, designated asNYSA, NYSD, NYSE, NYSF(dominant) andnysB,nysC(recessive) are responsible for resistance to nystatin ranging from 30 to 80 u/ml. A dominant modifier gene increases the resistance conferred byNYSFfrom 80 to 140 u/ml and a recessive modifier gene enhances resistance due toNYSAby 20 u/ml (from 40 to 60 u/ml). One nystatin-resistant mutant is apparently cytoplasmic and this ‘mutation’ suppresses specifically the action of modifying factors which increase the level of resistance conferred by theNYSAgene. Interaction resulting in additive levels of resistance is shown by geneNYSDin combination with each of the genesnysB,nysCandNYSE. A model of step-wise increases in resistance due to polygenic primary genes and nuclear and cytoplasmic modifying factors is proposed.
The contribution of plasmid and host genes to plasmid-mediated interference with phage growth
Authors: Hughes Victoria , Meynell G. G. 
Published: September 2009

SUMMARYThe R factors, R56 and R64, interfere with the growth of several otherwise unrelated phages, including λ, P22 and T7. In addition, λviris inhibited more strongly in λ lysogens carrying either R factor when the prophage has an intact O – P region. Interference does not occur in certainstr AR+hosts but may reappear if they also carry other mutations affecting ribosomal proteins. Host mutants not permitting interference were isolated but were notstrA. Non-interfering plasmid mutants were also isolated, of which some also failed to cause interference after transfer to a different host genus.
Allosuppressors in yeast
Authors: Cox B. S. 
Published: September 2009

SUMMARYFive loci have been identified inSaccharomyces cerevisiaewhose function reduces suppressor activity in strains carrying ochre super-suppressor mutations. Recessive mutations which allow an increased level of suppression occur at these loci. In such mutants, termed allosuppressors, the serine-inserting suppressorSUPQ5suppresses ochre mutations in a [psi−] background and Class I tyrosine-inserting suppressors are lethal or have a reduced viability. Mutations at two allosuppressor loci,sal3 andsal4, have a lethal interaction with one another and with the extrachromosomal determinant [psi+]. This interaction is expressed in the absence of any suppressor mutation. All the mutant alleles of one allosuppressor locussal3 are cold sensitive. One allosuppressor mutation,sal4.2, is temperature-sensitive for growth, as well as for other aspects of its phenotypic expression; namely the expression ofSUPQ5and the lethal interactions with Class I super-suppressors, with [psi+] and withsal3. At low temperature (24 °C),sal3-sal4.2 double mutants weakly suppress the ochre mutationade2.1, but do not suppresshis5.2 orlys1.1. It is argued that the site of function of the products of these loci is ribosomal and that they are involved in chain termination at UAA codons. It is inferred that the [psi+] factor or its product affects protein synthesis by interaction with the ribosome.
Continuous variation of genic dosage inPhycomyces
Authors: Medina Juan Ramon 
Published: September 2009

SUMMARYA computer simulation of the genetic analysis of the asexual life cycle ofPhycomyces' heterokaryons has been carried out. We have studied experimentally the relationship between the nuclear proportion in heterokaryotic mycelia containing prototrophic and auxotrophic nuclei and their growth rates. We discuss possible evolutionary implications of heterokaryosis in coenocytic fungi and the genetic applications of the quantitative complementation technique.
Polymorphism at the G6PD and 6PGD loci inDrosophila melanogaster: I. Evidence for selection in experimental populations
Authors: Bijlsma R. , van Delden W. 
Published: September 2009

SUMMARYGene frequency changes were followed in 17 experimental cage populations ofDrosophila melanogasterpolymorphic for the two loci G6PD and 6PGD. From these cages it was observed that selection was favouring theFalleles of both loci when the cages were started with low frequencies of these alleles (0·20Fand 0·50F). A viability experiment and an extinction experiment also provided evidence that theFalleles of both loci were favoured. It is argued that the observed selection is not due to selective differences in genetic background of the different alleles, but is acting on the isozyme loci themselves.
A plasmodial colour mutation in the MyxomycetePhysarum polycephalum
Authors: Anderson R. W. 
Published: September 2009

SUMMARYA spontaneous mutation conferring white plasmodial colour on the MyxomycetePhysarum polycephalumhas been analysed. The mutantwhi-1 allele is recessive towhi+in both heterokaryotic and heterozygous plasmodia. Thewhilocus is unlinked tomt, npfA, fusAandleu.
Theoretical study on genetic variation in multigene families
Authors: Ohta Tomoko 
Published: September 2009

SUMMARYGenetic variation contained in a multigene family was theoretically investigated from the standpoint of population genetics. Unequal crossover is assumed to be responsible for the coincidental evolution of mutant genes in a chromosome. When the allowed latitude of the duplicated or deleted number of gene units at unequal crossover is 10 ˜ 15% of the total gene number in a chromosome, the arrangement of gene lineage in a chromosome is shown to be roughly random. The equilibrium properties of genetic variation or the probability of identity of two genes within a family (clonality) were studied under mutation, unequal crossover, interchromosomal crossover and sampling of gametes. The clonality of a multigene family withina chromosomeis shown to be approximatelyin which α = 2k/n2withk= effective number of cycles of unequal crossover and withn= number of gene units in a family,vis the mutation rate per gene unit, β is the rate of interchromosomal crossover per family andNeis the effective size of the population, all measured by the rate per generation. The clonality of a gene family betweentwo different chromosomesbecomes approximatelyC1=C0/(l + 4Neν). Some models of natural selection which lowers the clonality or increases genetic variation in a multigene family were investigated. It was shown that natural selection may be quite effective in increasing genetic variation in a gene family.
Skeletal polymorphism and genetic drift in a Delhi frog, Rana cyanophlictis – a follow-up study
Authors: Grewal Manjit Singh 
Published: September 2009

SUMMARYFour isolated populations of the skipper frog, Rana cyanophlictis were first studied in 1965 and then again in 1975. The genetical changes were measured by the incidence of 19 non-metrical skeletal variants. It was found that these populations have changed very little in 10 years, although the inter-population diversity, as judged by the estimates of divergence, is less now than previously. This could be due to the similar environmental conditions prevailing in Delhi and its neighbourhood from where these frog populations were collected.
Radiation-inducedalcohol dehydrogenasemutants in maize following allyl alcohol selection of pollen
Authors: Freeling Michael , Cheng David S. K. 
Published: September 2009

SUMMARYThealcohol dehydrogenase-1gene in maize presents advantages for mutational analysis. Foremost among these is the ability to chemically select ADH-negative and ADH-low gametophytes owing to their resistance to allyl alcohol vapour. Immature tassels were irradiated with either 220 kV X-rays or 400 MeV/amu accelerated neon-ions; spontaneous mutants were also selected and recovered. RBE for neon-20 was about 5. A total of 70 presumptive mutants were placed into one of four classes on the basis of allozyme profiles following electrophoresis and ADH staining: (A) dysfunction, (B) underproducer, (C) overproducer, and (D) up-Adh2gene. Mutants have been recovered and confirmed in the first three classes. These include two male-transmissible deletion-type lesions induced by X-rays, five underproducer transpositions and one overproducer transposition induced by neon-20. Certain of the neoninduced alleles are unstable in their expression. All 70 mutants are chromosomal aberrations; no intragenic lesions were recovered although our experimental design would have preferentially recovered them if they had occurred.The Discussion considers the mutagenic action of ionizing radiation, and especially the well-documented differences between maize and Drosophila data. In particular, the effect of these chromosome derangements on the ‘programmable’ component(s) of theAdhlcistron is discussed.