bluuebunny/crossref_metadata_2025_split huggingface dataset:
cDNA sequence and chromosomal localization of the mouse parvalbumin gene,Pva
Authors: Zühlke Ch. , Schöffl F. , Jockusch H. , Simon D. , Guénet J.-L. 
Published: September 2009

SummaryIn the homozygous condition, the mutationadr(arrested development of righting response) of the mouse causes a myotonia and a drastic reduction of the Ca2+-binding protein parvalbumin (PV) in fast muscles. Using a rat PV probe, a mouse cDNA clone was isolated from a λgt11 wild-type fast-muscle library and its nucleotide sequence was determined. The protein coding and the 3′ non-translated regions of the mouse gene show extensive homology with the rat PV gene. The result of Southern blot hybridization is consistent with a single copy gene for parvalbumin. Restriction fragment length polymorphisms (RFLPs) betweenMus musculus domesticus(e.g. C57BL/6) andMus spretus(SPE) were detected with the enzymesEcoRI,PstI, andSstI. The restriction fragment patterns of DNA samples from 65 individual offspring of (C57BL/6 × SPE)F1 × C57BL/6 backcrosses were tested with the PV probe and matched, for linkage detection, to pre-existing patterns established with various RFLP probes on the same samples. A co-distribution of PV-RFLPs withPvt-1 andMlvi-2, which had been localized on chromosome 15, was detected. Thus, the structural gene for PV, designatedPva, maps to chromosome 15 of the mouse whereas theadrmutation shows no linkage with markers on this chromosome. Gene locus homology between chromsome 15 of the mouse and chromosome 22 of man (which carries the human PV gene) is discussed.
A study of ten families of transposable elements onXchromosomes from a population ofDrosophila melanogaster
Authors: Charlesworth Brian , Lapid Angela 
Published: September 2009

SummaryData were collected on the distribution of ten families of transposable elements among fourteenXchromosomes isolated from a natural population ofDrosophila melanogaster, by means ofin situhybridization to polytene chromosomes. It was found that, with the exception ofroo, the copy number per chromosome followed a Poisson distribution. There was no evidence for linkage disequilibrium, either within or between families. Some pairs of families of elements were correlated with respect to the identity of the sites that were occupied in the sample, although there was no evidence for a correlation with respect to the sites at which elements attained relatively high frequencies. Elements appeared to be distributed randomly along the distal part of theXchromosome. There was, however, a strong tendency for elements to accumulate at the base of the chromosome. Element frequencies per chromosome band were generally low, except at the base of the chromosome where bands in subdivisions 19E and 20A sometimes had high frequencies of occupation. These results are discussed in the light of models of the population dynamics of transposable elements. It is concluded that they provide strong evidence for the operation of a force or forces opposing transpositional increase in copy number. The accumulation of elements at the base of the chromosome is consistent with the idea that unequal exchange between elements at non-homologous sites is such a force, although other possibilities cannot be excluded at present. The data suggest that the rate of transposition per element per generation is of the order of 10−4, for the elements included in this study.
P-element transposase induces male recombination inDrosophila melanogaster
Authors: McCarron Margaret Y. , Duttaroy Atanu , Doughty Glenn A. , Chovnick Arthur 
Published: September 2009

SummaryMale recombination in P–M dysgenic crosses has been viewed as a reflection ofP-element transposase interacting withPelements. However, recent studies suggest that the transposase may catalyse double-stranded breaks in chromosomal DNA. We have, therefore, introducedP(Δ2–3ry+) (99B), a single non-mobileP-element transposase source, into the long-standing laboratory trueMstrains of a flanking lethal crossover selective system, thus facilitating the examination of rare male recombination events as an assay for transposase activity. We find that the rate of male recombination in the presence of this non-mobilePelement is greater than twenty times the background rate of male recombination in the control examined prior to introduction of the transposase source.
Acrosin activity in spermatozoa from sterilet6/tw32and fertile control mice
Authors: Mittal Ram Devi , Wileman Geraldine , Hillman Nina 
Published: September 2009

SummarySpermatozoa from sterilet6/tw32and control fertile + / +,T/tw32,T/t6mice were compared for their abilities to hydrolyse protein matrices and for their levels of acrosin activity. The data show that the immature and mature gametes from both the experimental and control males hydrolyse protein matrices. The quantitative acrosin assays show, however, that the mature gametes from the intercomplement males have significantly less total acrosin activity than any of the control groups of gametes. These findings suggest that this reduced acrosin activity is an additional phenotypic expression of the intercomplement genotype which results in male sterility.
Origin of rare Ha-ras alleles: relationship of VTR length to a 5′ polymorphic Xho I site
Authors: Baxter Glenn D. , Hayward Nicholas K. , Collins Russell J. , Lavin Martin F. 
Published: September 2009

SummaryAmongst the four common Ha-ras alleles in both controls and cancer patients, we detected the presence of a polymorphic Xho I site associated specifically with the 6·6 and 7·7 kb Bam HI fragments but absent from the 7·1 and 8·2 kb alleles, as recently reported by others. We have extended this study and report here, the consistent appearance of this Xho I site in unusual alleles close in size to the two common alleles of 6·6 and 7·7 kb, in control lymphoblastoid DNA samples in a variety of tumor DNAs. Unusual alleles grouped around the 7·1 and 8·2 kb common alleles on the other hand, did not possess the Xho I site. The consistent presence of the Xho I site polymorphism, in the unusual Ha-ras alleles surrounding the 6·6 and 7·7 kb common alleles and its absence in alleles around the 7·1 and 8·2 kb common alleles, suggests that the unusual ones are derived from the corresponding common alleles to which they are closest in size.
Hybrid dysgenesis-induced response to selection inDrosophila melanogaster
Authors: Pignatelli Patricia M. , Mackay Trudy F. C. 
Published: September 2009

SummaryInDrosophila melanogaster, theP−MandI−Rsystems of hybrid dysgenesis are associated with high rates of transposition ofPandIelements, respectively, in the germlines of dysgenic hybrids formed by crossing females of strains without active elements to males of strains containing them. Transposition rates are not markedly accelerated in the reciprocal, nondysgenic hybrids. Previous attempts to evaluate the extent to which hybrid dysgenesis-mediatedPtransposition contributes to mutational variance for quantitative characters by comparing the responses to selection ofP−Mdysgenic and nondysgenic hybrids have given variable results. This experimental design has been extended to include an additional quantitative trait and theI−Rhybrid dysgenesis system. The selection responses of lines founded from both dysgenic and nondysgenic crosses showed features that would be expected from the increase in frequency of initially rare genes with major effects on the selected traits. These results differ from those of previous experiments which showed additional selection response only in lines started from dysgenic crosses, and can be explained by the occasional occurrence of large effect transposable element-induced polygenic mutations in both dysgenic and nondysgenic selection lines. High rates of transposition in populations founded from nondysgenic crosses may account for the apparently contradictory results of the earlier selection experiments, and an explanation is proposed for its occurrence.
Relationship between chromosome content and nuclear diameter in early spermatids ofDrosophila melanogaster
Authors: González Cayetano , Casal José , Ripoll Pedro 
Published: September 2009

SummaryWe have studied, using light microscopy, the relationship between chromosome content and nuclear diameter in early spermatids of males carrying different combinations of wild-type and compound chromosomes inDrosophila melanogaster. By using these genotypes we have been able to observe spermatid nuclei bearing various numbers of chromosomes ranging from only one sex chromosome and no major autosomes to almost twice the normal chromosome complement. We have found that variations in the chromosome content are accompanied by increasing the variance in early spermatid nuclear diameter; the more gametic classes produced, the higher the variance of nuclear diameters. These results indicate that measuring nuclear diameters in early spermatids represents a useful way to estimate the levels of meiotic non-disjunction and thereby to improve the characterization of lethal or male sterile mutants in which analysis of meiotic chrosome non-disjunction cannot be achieved by conventional genetic methods.
Gene dosage effects on transmission ratio distortion and fertility in mice that carrythaplotypes
Authors: Silver Lee M. 
Published: September 2009

SummaryCompletethaplotypes can be transmitted at distorted ratios from heterozygous +/tmale mice as a consequence oft-specific alleles at a series oft complex distorterloci (Tcd-1tthroughTcd-4t) and at complex responderlocus. Partialthaplotypes that lack theTcd-2tallele cannot be transmitted at the very high ratios characteristic of completethaplotypes. The breeding studies reported here tested the possibility that the absence ofTcd-2tcould be compensated for by the presence of double doses of otherTcdtalleles. The results indicate that a double dose ofTcd-4talone will not work, but that a double dose of bothTcd-1tandTcd-4tcan promote a very high transmission ratio in the absence ofTcd-2t. These results suggest that the extent to which transmission ratios are distorted is dependent upon the absolute level of expression of the individualTcdgenes. Further studies of genotypic effects on transmission ratio distortion, as well as fertility, lead to the suggestion of a fiftht complex distorter(Tcd-5) locus withinthaplotypes.
A population genetical model for sequence evolution under multiple types of mutation
Authors: Iizuka Masaru 
Published: September 2009

SummaryDNA sequencing and restriction mapping provide us with information on DNA sequence evolution within populations, from which the phylogenetic relationships among the sequences can be inferred. Mutations such as base substitutions, deletions, insertions and transposable element insertions can be identified in each sequence. Theoretical study of this type of sequence evolution has been initiated recently. In this paper, population genetical models for sequence evolution under multiple types of mutation are developed. Models of infinite population size with neutral mutation, infinite population size with deleterious mutation and finite population size with neutral mutation are considered.
An XXY mouse, the result of a rearrangement between one X and a Y chromosome
Authors: Evans Edward P. , Breckon George , Peters Josephine 
Published: September 2009

SummaryA male mouse with irregular white spotting, typical of piebald, s, arose during an experiment designed to search for mutations induced in spermatogonial cells by ethylnitrosourea (ENU). On being examined cytologically it was found to carry 40 chromosomes but was effectively XXY since one of the two X chromosomes present was distally fused to a Y chromosome. In common with the previously described XXY mice, all of which carried 41 chromosomes, the mouse was sterile with a total absence of germ cells. Because of this, it was not possible to determine if the white spotting was inherited. The spotting could not be related to any observable abnormality of chromosomes known to carry spotting genes, nor could it be linked in any way with the X and Y fusion. It was concluded from the cytological considerations and the time interval (6 months) that had elapsed between mutagen treatment and birth of the offspring, that whereas the spotting was probably the result of ENU damage in a spermatogonial stem cell, the XY fusion was probably a later and spontaneous event.
Meiotic imbalance in laboratory-produced hybrid males of Chorthippus parallelus parallelus and Chorthippus parallelus erythropus
Authors: Bella J. L. , Hewitt G. M. , Gosálvez J. 
Published: September 2009

SummaryThe grasshopper Chorthippus parallelus has two quite distinct subspecies, which meet along the Pyrenees forming a hybrid zone. Using silver staining we show that on the French side Cp. parallelus has three nucleolar organizer regions, on the L2, L3 and X chromosomes, while on the Spanish side Cp. erythropus has only two NORs, on the L2 and L3. Laboratory F1 hybrid males show reciprocal differences in the expression of NORs. When a Cp. erythropus is female parent the male progeny show four active NORs in mitotic cells and two silver precipitates in meiotic cells, as expected. But when a Cp. parallelus female donates the X with a NOR, her male offspring have a variable disrupted nucleolar expression. Some NORs are not expressed and extra sites of cryptic rDNA are revealed. Meiosis is more disturbed in this latter F1 cross with higher levels of polyploidy, but both Fls show around 90% spermatid abnormality. Such variation in rDNA expression is also found in individuals collected from the hybrid zone, and the role of this disturbance in affecting fitness is discussed.
Selection in different environments: effects on environmental sensitivity (reaction norm) and on mean performance
Authors: Falconer D. S. 
Published: September 2009

SummaryTo simplify the description of selection in two environments the terms ‘ antagonistic’ and ‘synergistic’ are used. Selection upwards in a bad environment or downwards in a good environment is antagonistic, the selection and the environment acting in opposite directions on the character. Synergistic selection is the reverse, upwards in a good environment or downwards in a bad, selection and environment acting in the same direction. Published experiments are reviewed to see how well they agree with two expectations. First, Jinks & Connolly (1973) showed that antagonistic selection reduces environmental sensitivity and synergistic selection increases it. The experiments reviewed showed many exceptions to this rule, but they all showed that sensitivity was less after antagonistic than after synergistic selection. This is shown to be simply the consequence of correlated responses being less than direct responses. Second, I suggested (Falconer, 1989) that antagonistic selection might be the best way to improve the mean performance in the two environments. In the experiments reviewed, antagonistic selection was significantly better than synergistic for changing the mean, but it is now shown that there is no theoretical justification for this expectation; if one type of selection is better in one direction the other ought to be better in the other direction.Expressions are given for the changes of mean performance and of sensitivity resulting from selection in one or other environment; these changes can be predicted from the parameters of the base population. In the experiments reviewed, an increase of mean performance accounted for 49% or more of the upward response. Equations are presented which allow the variance of mean performance, the variance of sensitivity, and the covariance of mean with sensitivity to be derived from parameters estimated in an unselected population, namely the variances in the two environments and the corresponding covariance. The variance of sensitivity that might be ascribed to scale effects is deduced. Directional selection in a single macro-environment is synergistic with respect to the micro-environmental differences, and is expected to increase environmental sensitivity and consequently to increase environmental variance. Stabilizing selection is antagonistic selection in both directions at the same time, and so is expected to decrease environmental variance.
Frequency of the transposable elementUqin Iowa stiff stalk synthetic maize populations
Authors: Lamkey Kendall R. , Petérson Peter A. , Hallauer Arnel R. 
Published: September 2009

SummaryTheUqtransposable element is one of two transposable elements consistently found in maize (Zea maysL.) populations. Populations developed from two independent recurrent selection programs initiated in the Iowa Stiff Stalk Synthetic (BSSS) maize population were tested for the frequency ofUqtransposable elements to determine howUqfrequency has changed with cycles of recurrent selection. In the first programme, 13 cycles of half-sib and S2progeny recurrent selection [BSSS(S)C13] have been completed and 10 of the 13 cycles were assayed for activeUqelements. In the second programme, 11 cycles of reciprocal recurrent selection [BSSS(R)C11] have been completed and five of the 11 cycles were assayed for activeUqelements. The frequency ofUqwas different for the two recurrent-selection programmes. The percentage of plants containing activeUqelements increased from 19% (BSSS) to 91% [BSSS(S)C13] at a linear rate after 13 cycles of half-sib and S2progeny recurrent selection, whereas the percentage of plants containing activeUqelements decreased from 19% (BSSS) to 0% [BSSS(R)C11] after 11 cycles of reciprocal recurrent selection, with extinction of theUqelement occurring between the fifth and sixth cycles of selection. Our data suggest that the increase in frequency ofUqwith half-sib and S2progeny recurrent selection was predominantly due to random genetic drift coupled with a selective advantage possibly associated with a region of the genome linked toUq. Neither replicative transposition or chromosome assortment and segregation can be invoked to explain the change in frequency ofUqin these populations. The extinction ofUqafter reciprocal recurrent selection was best explained by random genetic drift.
Production of X0 clones in XX females ofDrosophila
Authors: Bachiller Daniel , Sánchez Lucas 
Published: September 2009

SummaryThe experiments reported here are aimed at determining whether mutations deleting the function of theSex-lethal(Sxl) gene are able to suppress the lethality of X0 clones, induced in females after the time when the state of activity ofSxlis irreversibly fixed by the ratio of the number of X chromosomes to sets of autosomes (X: A). This analysis was carried out by comparing the frequency of induced male clones (X0 constitution) inSxlfLS/ + andSxl+/Sxl+females, following irradiation at blastoderm and larval stages. The genotype used in these experiments, however, could also give rise to 2X; 2A cells homozygous forSxlfLS, and such cells would also differentiate male structures. To minimize this possibility, we have constructed a genotype made up of a ring and a rod X chromosome. In such ring-rod females the production of 2X; 2A clones homozygous forSxlfLSis a rather rare event, if possible at all. X0 male clones were produced in both types of females following irradiation at blastoderm stage, while X0 male clones were only observed inSxlfLS/ + females when irradiation took place at larval stage. In this latter case, the only X0 male clones were those that contained theSxlfLSmutation. These results support the idea of Sánchez & Nöthiger (1983) that the X: A signal irreversibly sets the state of activity ofSxlat blastoderm stage, and in addition show that X0 clones generated after that time are viable if they contain aSxl−mutation. These results are compatible with the idea ofSxlbeing the only gene that responds to the X:A signal.
Meiotic drive of t haplotypes: chromosome segregation in mice with tertiary trisomy
Authors: Agulnik Alexander I. , Agulnik Sergei I. , Ruvinsky Anatoly O. 
Published: September 2009

SummaryThe properties of the t haplotypes, specific mutant states of the proximal region of chromosomes 17 in the house mouse, are of continuing interest. One such property is increased transmission of the t haplotype by heterozygous t/ + males to offspring. Using the reciprocal translocation T(16; 17)43H we have constructed males with tertiary trisomy of chromosome 17 (+ T43/+ +/Rb7 + ) carrying the Robertsonian translocation Rb(16.17)7Bnr. Only the progeny of these males which had inherited either T43/ + or Rb7 from their male parent were viable. The segregation patterns in the offspring of t-bearing trisomics were analysed on days 16–18 of embryonic development. It was found that, when the t12 haplotype is in the normal acrocentric (♂♂ + + T43/ + t12 + /Rb7 + +), its presence in the gamete + t12 + / + + T43 does not produce meiotic drive. However, when t6 is in Rb7, meiotic drive was observed: 80% of offspring carried the t haplotype. It is concluded that the meiotic drive is probably inhibited by the presence of a normal homologue of chromosome 17 in the same sperm. Possible mechanisms for the t haplotype effect are discussed.
Partial complementation by murinethaplotypes: deficit of males amongt6/tw5double heterozygotes and correlation with transmission-ratio distortion
Authors: King Thomas R. 
Published: September 2009

SummaryTo evaluate whether sex reversal contributes to sex-ratio imbalance amongt6/tw5double heterozygotes, the cross performed by K. B. Bechtol (Genetical Research39, 1982, 79–84),T/t6×T/tw5, was repeated. Significantly more normal-tailed (t6/tw5) females than males were recovered. By contrast, sex ratios were normal among tailless progeny resulting from this cross and among all classes produced by control crosses. Hybridization of a Y-specific DNA probe with genomic DNA from phenotypic females revealed no XY, sex-reversed males. On the genetic backgrounds that generated only moderate transmission distortion oftw5(81–85%), the overall viability of the doubly heterozygous progeny was only 50% and the sex-ratio skew among this class was strong. However, on a genetic background that displayed extremetw5transmission (99%), embryonic viability was more than 80% and the sex-ratio imbalance was weak.
Biochemical and genetic characterization of esterase-27 (ES-27), the major plasma cholinesterase of the house mouse (Mus musculus)
Authors: von Deimling O. H. , Gaa A. 
Published: September 2009

SummaryEsterase-27A (ES-27A) was characterized in strain A/WySnA by a cascade of seven bands seen after disc electrophoresis of serum and subsequent staining for esterase. ES-27A catalyses the hydrolysis of thiocholine butyrate and is strongly inhibited by 100 μm tetraisopropyl pyrophosphamide (isoOMPA). Hence, the enzyme was concluded to be a cholinesterase EC 3.1.1.8. A heat-labile form termed ES-27B was represented by strain AKR/Han. From a three-point cross (AKR/Han, A/Wy) and a five-point cross (AKR/Han, SEG/1), the gene order on chromosome 3 was concluded to be centromere–Car-2–Es-26–Es-27–Amy-1–Adh-1.