bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of lines of mice selected for fat content. 2. Correlated responses in the activities of enzymes involved in lipogenesis
Authors: Hastings Ian M. , Hill William G. 
Published: September 2009

SummaryEstimates of the activities (Vmax) of six enzymes involved inde novofat synthesis were made in replicated lines of mice differing in fat content. These lines had been selected high and low for 20 generations with three replicates each of Fat, Control and Lean lines and for a further eight generations high and low as an unreplicated line. The activities of ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACC), fatty acid synthetase (FAS), cytoplasmic malate dehydrogenase (MDH), malic enzyme (ME) and pyruvate kinase (PK) were determinedin vitroin both liver and gonadal fatpad tissues taken at ages five and ten weeks. The activities of ACL, ACC, FAS and ME were significantly higher in the Fat than the Lean lines, and the differences were more pronounced at the earlier age and in the gonadal fatpad where activities in the Fat lines were higher by factors of 3·5, 2·4, 2·5 and 3·5 respectively. The activity of PK was unchanged in each tissue. MDH activity was significantly lower in adipose tissue in the Fat lines than the Lean lines at age ten weeks but not at age five weeks or in liver tissue. Results from replicates indicated that random genetic drift affected enzyme activities but nevertheless significant changes in activity were associated with the direction of selection. The changes in enzyme activity reported here are similar to those known to be associated with major mutations causing obesity in mice.
The use of maternally coded gene products inDrosophila
Authors: Robbins Leonard G. 
Published: September 2009

SummaryBoth maternal and zygotic expression of many essential genes are required for normal development. For some of these genes, absence of maternal function yields striking embryonic defects. The experiments reported here examine two questions about such genes: (1) Are embryonic effects of maternal deficits a common property of maternally-and-zygotically active genes? and (2) Is use of the maternal products of these genes restricted to early embryogenesis? A comparison of times of lethality of mutant sons of normal and mutant-heterozygous mothers has been made for six mutations in thezeste-whiteregion of theDrosophila Xchromosome. Four of the mutations are defective in single cistrons and two are deficiencies that between them remove thirteen essential loci. All of these mutations had previously been shown to have both maternal and zygotic effects, and all of them had been tested, using homozygous germ-line clones, for the effects of complete maternal defects. For several of them, homozygous germ-line clones cause embryonic defects. Of the six, only one,Df(l)K95, shows a shift from larval to embryonic lethality when the mothers are heterozygous, and even in that case lethality occurs at the very end of embryogenesis. These results have two implications: (1) maternally-derived transcripts do not always serve a solely embryonic role; and (2) an embryonic effect of a complete maternal deficit does not by itself demonstrate an embryo-restricted function for the maternal transcript.
Assignment of the mouse desmin gene to chromosome 1 band C3
Authors: Li Zhenlin , Mattei Marie-Geneviève , Mattei Jean-François , Paulin Denise 
Published: September 2009

SummaryThe chromosomal localization of the mouse gene coding for desmin, one of the muscle-specific intermediate filament subunits, was determined byin situhybridization using a specific3H-labelled DNA probe. There is only one copy of the desmin gene and it is located on chromosome 1 in the band C3. This result adds an eleventh locus to a conserved gene cluster and confirms the partial homology that exists between the long arm of human chromosome 2 and chromosome 1 of the mouse.
Analysis of a rare recombination event within the multigenic Hor 2 locus of barley (Hordeum vulgare L.)
Authors: Shewry Peter R. , Parmar Saroj , Franklin Julian , Burgess Shirley R. 
Published: September 2009

SummaryA rare recombinant within the multigenic Hor 2 locus of barley was detected by SD-PAGE of hordein fractions from F2 grain from the cross Bomi × P12/3. Analysis of a homozygous F4 line by 2-D IEF/SDS-PAGE showed that recombination between the class I/II and class III subfamilies of genes had occurred, indicating that they are spatially separate within the Hor 2 locus. RFLP analysis using a B hordein-related cDNA clone confirmed that recombination had occurred, while similar analysis using a genomic clone related to γ-type hordein (encoded by the Hor 5/HrdF locus) indicated the order of the two subfamilies of genes on the short arm of chromosome 5, the class I/II genes being closer to the centromere. The results are consistent with the origin of the B hordein gene family from initial duplication of a single ancestral gene to give two genes which diverged to become the ancestors of the class I/II and class III subfamilies. Subsequent cycles of duplication and divergence have resulted in the present high degree of polymorphism.
Elevated galactosyltransferase activity ont-bearing sperm segregates with T/t-complex distorter loci-2
Authors: Shur Barry D. , Scully Natalie F. 
Published: September 2009

SummarySperm bearing completet-haplotypes are preferentially transmitted during fertilization from heterozygous +/tmales, often in excess of 95% relative to their +-bearing meiotic partner. Sperm fromt-bearing males have an approximate two- to fourfold increase in β1, 4-galactosyltransferase (GalTase) activity, a cell surface protein that mediates sperm binding to the egg zona pellucida. The elevated GalTase activity strictly correlates with the preferential transmission oft-sperm from +/tmales, since eight other enzymes show normal levels of activity ont-sperm. Furthermore, sperm bearing proximal partialt-haplotypes, which are no longer favoured during fertilization, have normal levels of GalTase activity. Nevertheless, it has been unclear whether the elevated sperm GalTase activity ont-sperm is due to specific loci in the distal segment of the T/t-complex, or rather, is an indirect consequence of the abnormal sperm function characteristic of +/tandtx/tymales. In this study, it is shown that the elevated sperm GalTase activity is due specifically to factors that reside within the distal segment of the T/t complex, which also containsTcd-2, the strongest of the distorter loci. Since the structural locus for GalTase is located on mouse chromosome 4, these results also show that T/t-complex alleles on chromosome 17 are regulatory in nature and affect the expression of sperm surface components critical for normal fertilization. Models are presented to explain how elevated GalTase activity could contribute to sperm transmission distortion.
The effect of biased conversion on the mutation load
Authors: Bengtsson Bengt O. 
Published: September 2009

SummaryThe mutation load is sensitive to changes in the segregation ratio caused, for example, by biased conversion. If the distortion, measured by the force of conversion, is greater than the loss of fitness in the mutation heterozygotes, then the mutation load will be far away from its normal value. Examples are given where a small positive bias together with realistic fitness parameters increase the mutation load by more than two orders of magnitude.In practical terms this implies that great restrictions should be placed on the use of substances and treatments that may induce mutations associated with a positive conversion bias.
Selection response in traits with maternal inheritance
Authors: Lande Russell , Kirkpatrick Mark 
Published: September 2009

SummaryMaternal inheritance is the non-Mendelian transmission of traits, from mothers to their offspring. Despite its presence in virtually all organisms, acting through a variety of mechanisms, the evolutionary consequences of maternal inheritance are not well understood. Here we review and extend a model of the inheritance and evolution of multiple quantitative characters with complex pathways of maternal effects. Extensions of the earlier model include common family environmental effects not associated with maternal phenotype, sexual dimorphism, and paternal effects (non-Mendelian influence of the father on offspring traits). We find that, in contrast to simple Mendelian inheritance, maternal inheritance produces qualitatively different evolutionary dynamics for two reasons: (1) the response to selection on a set of characters depends not only on their additive genetic variances and covariances, but also on maternal characters that influence them, and (2) time lags in the response to selection create a form of evolutionary momentum. These results have important implications for evolution in natural populations and practical applications in the economic improvement of domesticated species. We derive selection indices that maximize either the economic improvement in a single generation of artificial selection or the asymptotic rate of improvement in long-term selection programmes, based on individual merit or a combination of individual and family merit. Numerical examples show that accounting for maternal inheritance can lead to considerable increases in the efficiency of artificial selection.
Mutation-selection balance and the evolutionary advantage of sex and recombination
Authors: Charlesworth Brian 
Published: September 2009

SummaryMutation-selection balance in a multi-locus system is investigated theoretically, using a modification of Bulmer's infinitesimal model of selection on a normally-distributed quantitative character, taking the number of mutations per individual (n) to represent the character value. The logarithm of the fitness of an individual withnmutations is assumed to be a quadratic, decreasing function ofn. The equilibrium properties of infinitely large asexual populations, random-mating populations lacking genetic recombination, and random-mating populations with arbitrary recombination frequencies are investigated. With ‘synergistic’ epistasis on the scale of log fitness, such that log fitness declines more steeply asnincreases, it is shown that equilibrium mean fitness is least for asexual populations. In sexual populations, mean fitness increases with the number of chromosomes and with the map length per chromosome. With ‘diminishing returns’ epistasis, such that log fitness declines less steeply asnincreases, mean fitness behaves in the opposite way. Selection on asexual variants and genes affecting the rate of genetic recombination in random-mating populations was also studied. With synergistic epistasis, zero recombination always appears to be disfavoured, but free recombination is disfavoured when the mutation rate per genome is sufficiently small, leading to evolutionary stability of maps of intermediate length. With synergistic epistasis, an asexual mutant is unlikely to invade a sexual population if the mutation rate per diploid genome greatly exceeds unity. Recombination is selectively disadvantageous when there is diminishing returns epistasis. These results are compared with the results of previous theoretical studies of this problem, and with experimental data.
A newt-complex embryonic lethal (tcl0) has arisen in theThpchromosome of the mouse and is allelic tot0
Authors: Sanchez Edwin R. , Hammerberg Craig 
Published: September 2009

SUMMARYComplement testing of aThpline revealed a failure of survival ofThp/t0embryos. The genetic factor responsible for this lethality maps between Brachyury (T) and tufted (tf) on the murine seventeenth chromosome. This lethal factor permits recombination betweenTandtfand does not affect the transmission of its seventeenth chromosome. Its effect upon embryonic development is similar to that of thet0haplotype. It would appear to represent a point mutation of a single gene,t-complex lethal zero(tcl0).
Cattanach's translocation [Is(7:X)Ct] corrects male sterility due to homozygosity for chromosome 7 deletions
Authors: Erickson Robert P. 
Published: September 2009

SUMMARYMice carrying particular deletions of chromosomal material at and around the colour (C) locus on chromosome 7 (c3H/c6H) are viable but sterile. An insertional translocation of chromosome 7 into theX(Cattanach's) has been previously used to rescue females carrying deletions of chromosome 7 which are ordinarily lethal. We studied the ability of this translocation to correct the sterility found in the presence of the two partially complementing deletions. We predicted that the sterility would be corrected in females who would be mosaics because of X-inactivation. The result in males was uncertain since the sterility had been shown to be due to defective spermatogenesis, and the X chromosome is inactivated early in the course of spermatogenesis. Thec3H/c6Hmale and female deletional sterility were rescued by Cattanach's translocation.
Variation in the shape of the mouse mandible: 1. Effect of age and sex on the results obtained from the discriminant functions used for genetic monitoring
Authors: Lovell D. P. , Totman P. , Johnson F. M. 
Published: September 2009

SUMMARYThe shape of the mandible of the mouse can be described by a series of discriminant functions which have been used to discriminate between and investigate relationships among strains of mice. The effect of sex and variation in age of the animal on the results obtained from these functions has been investigated. Significant sex differences in mandible shape were detected, but these were considerably smaller than the differences found between two inbred strains. A simple correction for expressing each measure as a proportion of the sum of the measures on each bone removes the effects of overall size. Significant age effects were found, but these were only large in animals under seven weeks of age where considerable changes are taking place in the relative lengths of bone measurements. Routine testing for genetic authenticity using the shape of the mandible is possible over a wide age range and may be an efficient method for monitoring genotypes at the end of long-term experiments.
Two locally acting genetic controls of gene conversion,ccf-5andccf-6, inAscobolus immersus
Authors: Howell W. M. , Lamb B. C. 
Published: September 2009

SUMMARYTwo new conversion control factors (ccfs),ccf-5andccf-6, have been characterized in the Pasadena strains ofAscobolus immersus. Both are monogenic, with two known allelic forms (calledAandB) of each factor, and affect the frequency of meiotic gene conversion at awhite(w) ascospore locus closely linked to it,ccf-5affectingw-9andccf-6affectingw-BHj. Theccfs appear to be specific to their own target site, with no effect on at least nine unlinkedwmutations. Conversion of thewlocus affected was studied in + ×wcrosses with all four possibleccfarrangements: for example, for + ×w-9, withccf-5(A) in both parents, withccf-5(B) in both parents, withccf-5(A) in +,Binw-9, and withccf-5(B) in +,Ainw-9. For bothccfs, there were slight differences between crosses homozygous forAand those homozygous forB, and also slight differences between the two forms of heterozygous cross,A/BandB/A, but the major effect was for heterozygosity for the control factor to depress conversion frequency of thewlocus, compared with either homozygous state. These twoccfs are compared with other sites affecting recombination in fungi and higher eukaryotes. Two possible modes of action ofccfs5and6are (i) on pairing closeness before hybrid DNA initiation, and (ii) on later stages such as the spread of hybrid DNA from an initiation point.
Genetic and environmental modification of gene expression in thebrlA12variegated position effect mutant ofAspergillus nidulans
Authors: Clutterbuck A. J. , Spathas D. H. 
Published: September 2009

SUMMARYThebrlA12variegated position effect mutant is particularly suited for tests of environmental and genetic influences on variegation, but out of a large number of substances added to the medium, only salts at high concentrations and methylamine significantly increased expression of this gene. Medium shifting experiments showed thatbrlA12activity could be switched on late, but once active, was rarely switched off again during conidiation. SeparatebrlA12clones in heterokaryons were activated independently. SomebrlA12-specific suppressor mutants, including those at loci giving almost complete suppression, have been studied. One class of suppressors also confers inability to utilize galactose as carbon source and comparison with other, pre-existing mutants showed that thebrlA12phenotype was either suppressed or enhanced by mutants with complex phenotypes involving galactose utilization, molybdate resistance, acid phosphatase production and sulphur metabolism. Tests for the involvement of DNA methylation inbrlA12expression gave negative results.
AnSD(Segregation Distribution) –MR(Male Recombination) chromosome isolated from a natural population ofDrosophila melanogaster
Authors: Bencze Gábor , Slatko Barton E. 
Published: September 2009

SUMMARYA second chromosome line ofDrosophila melanogaster(S-90), isolated from a northern California natural population, is able to induce (1) an increased frequency of X-chromosome visible mutations, (2) male recombination activity subject to reciprocal cross suppression, and (3) strong meiotic drive from heterozygous males. Based upon several lines of evidence (including the response to suppressor chromosomes of both systems) we conclude thatS-90contains bothSD(Segregation Distortion) andMR(PorI) chromosome activity. The two systems appear to behave independently and simultaneously, and a small centromeric region of theS-90chromosome appears to contain the major genetic elements of both systems.
The DNA transposition system of hybrid dysgenesis inDrosophila melanogastercan function despite defects in host DNA repair
Authors: Slatko Barton E. , Mason James M. , Woodruff R. C. 
Published: September 2009

SUMMARYGenetic traits associated with the hybrid dysgenesis syndrome were quantified in strains deficient in two major host-coded DNA repair pathways, post-replication and excision repair. A defect in either (or both) pathway(s) fails to influence the frequency of male recombination or sex-linked recessive lethal mutations associated with hybrid dysgenesis, suggesting that the DNA transposable elements associated with this syndrome act independently of these cellular functions. However, when the post-replication repair pathway is blocked, the recovery of second chromosomes containing factors associated with hybrid dysgenesis activity is reduced. The decrease in recovery is associated with zygotic lethality.
Two-way within-family and mass selection for 8-week body weight in different mouse populations
Authors: von Butler Ines , Willeke Henning , Pirchner Franz 
Published: September 2009

SUMMARYTwo mouse populations, randombred albino mice and a cross of four inbred strains, were divergently selected for high (H8) and low (L8) 8-week body weight over 18 generations using within-family and individual selection. The crossbreds showed asymmetry of selection response and realized heritabilities (H80·29 ± 0·01; L80·17 ± 0·01). In the randombred population realized heritabilities were symmetrical (H80·23 ± 0·01; L80·22 ± 0·02). Over the first nine generations individual selection was nearly 40 per cent better than within-family selection, as was expected from the full sib correlation in both populations. As selection progressed, within-family selection reached 82% and 61% of the responses obtained with individual selection in the crossbreds and randombred respectively. Correlated responses for 3-week (weaning) and 5-week body weights agreed with observations made on direct responses, but selection for L8did not reduce weaning weight. Selection for L8decreased and selection for H8increased first litter size at birth. However, mass-selected L8-pairs had a higher life-reproduction and life-span than H8-pairs.
Potential for hitchhiking in theeda-edd-zwfgene cluster ofEscherichia coli
Authors: Dykhuizen Daniel E. , De Framond Jean , Hartl Daniel L. 
Published: September 2009

SUMMARYThe locieda, eddandzwfform a tightly linked cluster inE. colithat functions in the metabolism of galacturonate, gluconate and glucose. This cluster has been transferred from six natural isolates into the genetic background ofE. coliK12 and examined with regard to effects on growth rate in chemostats. Although the naturally occurringedaandzwfalleles are selectively neutral, theeddalleles are not. Theeddalleles fall into three functional classes distinguished by their effects on growth rate in gluconate medium, the most common classes differing in fitness by approximately 1% per hour. This extensive non-neutral genetic variation ofeddis discussed in light of the evident rarity of gluconate as a natural substrate. We propose that gluconate selection is intermittent in space or time, providing the population an opportunity to accumulate non-neutral genetic variants during periods of relaxed selection. Such genetic variants will eventually be sorted out by the intermittent periods of gluconate selection, and during these periods the linkededaandzwfalleles will experience pronounced hitchhiking effects.
Variance-effective population number: the effects of sex ratio and density on the mean and variance of offspring numbers in the flour beetle,Tribolium castaneum
Authors: Wade Michael J. 
Published: September 2009

SUMMARYI report the results of an experimental study of the effects of sex ratio and density on the mean and variance in offspring numbers in both sexes of the flour beetle,Tribolium castaneum. The variance-effective number is estimated from the observed variance in offspring numbers using the methods of Crow & Morton (1955).Both the mean and the variance in offspring numbers were found to vary with sex ratio and density; as was found in previous studies (Wade, 1980), males were generally more variable in offspring numbers than females. The ratio of variance to mean progeny numbers in each sex was approximately unity at all sex ratios.
Effects of a temperature-sensitiveMinutemutation on gene expression inDrosophila melanogaster
Authors: Sinclair Donald A. R. , Grigliatti Thomas A. , Kaufman Thomas C. 
Published: September 2009

SUMMARYMinute(M) lesions exhibit a striking propensity for interacting with many different mutations. In the past, few attempts have been made to explain these diverse phenomena. This study describes a variety of temperature-sensitive (ts) interactions exhibited by the ts third chromosomeMinutemutationM(3)LS4Q-III(Q-III). Most of these interactions (i.e. those involvingvg, cp, Dl, DfdorLy) reflectQ-III-induced enhancement of the respective mutant phenotypes at the restrictive temperature. However,Q-IIIalso suppresses the extra-sex-comb phenotypes ofPcandMscat 29 °C and evokes lethal and bristle traits when combined withJ34eat the restrictive temperature. All of these interactions are characteristic of non-tsMinutelesions and thus they appear to be correlated with general physiological perturbations associated with theMsyndrome. In addition, our findings show that mutations that affect ribosome production and/or function, namelysu(f)ts67gandbbts−1, exhibit interactions comparable to those elicited byQ-III. Hence, in accordance with previous findings, we argue that most of theQ-IIIinteractions can be attributed to reduced translational capacity at the restrictive temperature. Finally, reciprocal temperature shift studies were used to delineate TSPs for interactions betweenQ-IIIandvg(mid to late second instar),cp(about mid-third instar),Dfd(early third instar) andDl(late second to mid third instar). We believe that these TSPs represent developmental intervals during which the respective gene products are utilized.