bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of an unusual chromosome architecture on disjunction and non-disjunction in Drosophila
Authors: Falk Raphael 
Published: September 2009

SUMMARYTwo homologous autosomes of Drosophila that were attached to form a single entire compound autosome II were found to affect the segregation of the sex chromosomes in both males and females. The compound segregated nearly always from an attachedX.Ychromosome in males with no other sex chromosome. When two sex chromosomes were present together with the compound they differed in their tendency to segregate from the compound. In males theX.Ychromosome segregated more often from the compound than did theYchromosome, and theYchromosome segregated more often from the compound than did the regularXchromosome. In females theX.Ysegregated more often from the compound than did the regularXchromosome. This preferential segregation in females was observed for exchangeXchromosomes as well as for the non-exchange chromosomes.In the presence of the compound the frequency of primary non-disjunction of the sex chromosomes was elevated in both females and males; usually both sex chromosomes segregatedfromthe compound and only rarelywithit.Flies devoid of most of the proximal heterochromatin of the sex chromosomes die. However, when the compound autosome was present some such flies survived. This indicates that a segment of the proximal heterochromatin of the sex chromosomes was intercalated into the compound when it was constructed. It was concluded that the segment intercalated into the compound carries specific sites for sex chromosome disjunction. Specific sites determine sex chromosome disjunction in males. In females they determine the disjunction of the sex chromosomes in cooperation with exchange pairing.
Genetic analysis of transmission ratio distortion byt-haplotypes in the mouse
Authors: Bennett Dorothea , Alton Althea K. , Artzt Karen 
Published: September 2009

SUMMARYLethal and semilethalt-haplotypes in the mouse are polymorphic in wild populations, where they are presumably maintained by transmission distortion from males, which transmit the aberrant chromosome to over 95% of progeny. We report here measurements of transmission ratio that show an unexpectedly strong effect of background genotype, specifically genes on the homologous chromosome, on the degree of transmission distortion oft-haplotypes. We also provide additional evidence that withint-haplotypes two separable elements co-operate to control transmission distortion, and that the system is thus closely analogous to segregation distortion in Drosophila, as has been previously proposed by Gluecksohn-Waelsch & Erickson (1970), Demin, Safronova & Lapkina (1978), and Styrna & Klein (1982).
Further studies on the alcohol dehydrogenases in barley: evidence for a third alcohol dehydrogenase locus and data on the effect of an alcohol dehydrogenase – 1 null mutation in homozygous and in heterozygous condition
Authors: Harberd N. P. , Edwards K. J. R. 
Published: September 2009

SUMMARYThis paper presents evidence that the alcohol dehydrogenases (ADHs) in barley are specified by three loci. Six distinct ADH isozymes are observed following native slab polyacrylamide gel electrophoresis of crude extracts from flooded wild-type roots. Three of these isozymes are missing in flooded roots of plants homozygous for the Adhl-M9 mutation. The results also indicate that a simple binomial model (incorporating random dimerization and no inhibitive interaction of the two subunit species within heterodimers) is unable to account for the distribution of the total ADH activity between the ADH isozymes observed. Finally, the level and distribution of ADH activity in heterozygous (Adhl+ / Adhl-M9) flooded roots is not what would be expected if these contain only one-half of the available ADH1 protomers and the same frequency of available ADH2 and ADH3 protomers as is contained in the flooded roots of wild-type homozygotes (Adhl + / Adhl + ).
Genetic variation of wild mouse populations in southern Germany: I. Cytogenetic study
Authors: Adolph Sabine , Klein Jan 
Published: September 2009

SUMMARYSome 400 wild mice (Mus domesticus) from southern Germany (the triangle formed by the cities Tübingen, Heidenheim and Friedrichshafen) were karyotyped and, in 243 of them, the chromosome compositions were determined by banding techniques. Virtually all mice tested carried at least one pair of metacentric chromosomes; some mice had up to ten metacentric chromosomes. Based on their chromosome composition, five mouse populations could be distinguished. Population I was characterized by the diploid chromosome number of 2n = 38 and the presence of two copies of metacentric chromosome Rb(4.12)1Tu. This translocation was also found in virtually all mice captured in southern Germany, almost always in a homozygous state. Mice of other populations had extra metacentric chromosomes Rb(5.15)15Tu (population II), Rb(13.14)17Tu (population III), Rb(5.14)18Tu (population IV) and Rb(11.13)6Tu (population V). In addition, rare variants (1 or 2 mice) were found in the different populations, which were heterozygous for additional metacentric chromosomes. Population V was quite heterogeneous in that it contained up to five metacentric chromosomes in addition to those mentioned. The number and the composition of these metacentric chromosomes varied from place to place. With the exception of population I, the individual populations occupied geographically distinct areas: Representatives of population I were found concentrated in one area, but, in addition, some were scattered over the entire studied region.
Production and modification of Mu (G–) phage particles inE. coli K12andErwinia
Authors: Toussaint Ariane , Schoonejans Eric 
Published: September 2009

SUMMARYWe studied the amount of Mu(G+) and Mu(G−) phages in different Mu lysates prepared either upon induction or upon infection ofE. coliandErwiniastrains. We also looked at the level of expression of the modification function (mom) by Mu(G−) phages, both after induction and after infection ofE. coliandErwinia. The expression ofmomseems to be regulated in the same manner inE. coliand in the strain ofErwinia carotovoratested. The proportion of both types of Mu(G+) and Mu(G−) phages in induced lysates is very variable and we found growth conditions favouring the production of Mu(G−) particles. This should extend the use of Mu as a genetic tool and as a generalized transducing phage to many enterobacteria.
Abuffspore colour mutant inSordaria brevicollisshowing high-frequency conversion: 2. Loss of the high-frequency conversion
Authors: Macdonald Mary V. , Whitehouse Harold L. K. 
Published: September 2009

SUMMARYA mutant, YS17, at thebuffspore colour locus inSordaria brevicollishas previously been described. It shows conversion with high frequency, predominantly to wild type, and is believed to act as a recognition site for an endonuclease that initiates recombination at the YS17 site. The discovery is now reported of a gene that causes loss of the high-frequency conversion shown by the YS17 mutant. The gene was present in existing stocks of the fungus. It reduces the conversion frequency of YS17 to a level similar to that of otherbuffmutants, from which it is inferred that the YS17 mutant no longer acts as an initiation site for recombination. When the conversion frequency of YS17 is low the bias in conversion to wild type rather than to mutant is lost, suggesting that this bias may relate to the initiation of recombination at the site. The loss of high frequency conversion of YS17 appears to be determined by a single recessive gene linked to mating type and unlinked tobuff. It is suggested that the dominant allele induces recombination at the site of YS17 by controlling either the synthesis or the activity of an endonuclease that is capable of recognising the nucleotide sequence at the YS17 site. Some anomalous results point to the existence of modifiers of the action of the gene.
Nitrite toxicity inAspergillus nidulans: a new locus in aproA1 pabaA6 yA2strain
Authors: Pombeiro Sandra R. C. , Martinez-Rossi Nilce M. , Rossi Antonio 
Published: September 2009

SUMMARYThis report describes the existence of a mutation in aproA1 pabaA6 yA2strain ofAspergillus nidulans, which prevents it growing on elevated concentrations of nitrite. The nitrite toxicity marker (nihA) resulted from a mutation in a single gene representing a new locus in linkage group I, and behaved as a recessive character. The observed recombination frequencies betweennihAandproA1and betweennihAandpabaA6were about 1 and 11%, respectively. Nitrite toxicity was not due to a defect in nitrite reductase, because the mutant grew well on nitrate. Furthermore, ammonium protected bothnis-5andniiA−strains against nitrite toxicity, which was not observed for thenihAstrain. Since growth of the mutant was inhibited more by a mixture of ammonium and nitrite, compared to nitrite alone, it is proposed that theproA1 pabaA6 yA2strain has a mutation leading to increased efficiency in nitrite uptake, which is not repressed by ammonium.
Shikimate dehydrogenase – a biochemical marker for group 5 chromosomes in the Triticinae
Authors: Koebner R. M. D. , Shepherd K. W. 
Published: September 2009

SUMMARYStructural genes for the isozymes of shikimate dehydrogenase (E.C.1.1.1.25) have been located on chromosome arms 5AS, 5BS and 5DS of wheat, 5RS of cereal rye and on chromosome 5CuofAegilops umbellulataby electrophoretic techniques. This character provides a useful genetic marker for these previously unmarked chromosome arms, and the results support the notion of the conservation of gene synteny groups within the Triticinae.
The intrachromosomal mapping of a glucose phosphate isomerase structural gene, using allelic variation among stocks of Chinese Spring wheat
Authors: Chojecki A. J. S. , Gale M. D. , Holt Linda M. , Payne P. I. 
Published: September 2009

SUMMARYDetectable allelic variation at theGpi-1loci on the short arms of the homoeologous group 1 chromsomes in wheat is not common. However, a variant null allele at theGpi-D1locus is present in some stocks of Chinese Spring. This has allowed the locus to be mapped between the ω-gliadin locus carried distally on the short arm of chromosome 1D,Gli-D1(34·5%) and the high-molecular-weight glutenin subunit locus carried near the centromere on the long arm,Glu-D1(36·2%). The origin of this isoenzyme polymorphism in Chinese Spring stocks is described and its potential significance is discussed in relation to quantitative analysis of aneuploids, alien chromosome addition and substitution lines and intervarietal chromosome substitution lines involving Chinese Spring.
Chromosomal control of early embryonic development in mice: II. Experiments on embryos with structural aberrations of autosomes 7, 9, 14 and 17
Authors: Baranov V. S. 
Published: September 2009

SUMMARYPerculiarities of preimplantation and early postimplantation development were studied in embryos with partial deletions and duplications of chromosomes 7, 9, 14 and 17, in the progeny of mice heterozygous for the unequal reciprocal translocations T(7; 14)2Iem, T(16; 17)43H and T(9; 17)138Ca. Deficiencies for any part of autosomes 9 or 14 combined with duplications of the corresponding segments of autosomes 7 or 17 do not affect preimplantation development, though they are lethal soon after implantation. Deficiency for the distal part of chromosome 7 (Df7F4) induces embryonic death by the early blastocyst stage. Deficiencies for the distal part of chromosome 17 (Df17El–E5), as well as for its proximal region (Df17AB) carrying all genes of theT-tcomplex, have no detrimental effects on cleavage, blastulation and implantation, but are lethal after implantation, mostly during early neurulation. Deficiency for the middle part of chromosome 17 (Df17CD) is expressed just after a few cleavage divisions, and these embryos all die by the morula stage. It is suggested that the genes of the CD region of chromosome 17 and of the F4 region of chromosome 7 are of major significance for genetic control of early development in the laboratory mouse.
Haematopoietic role for Patch (Ph) revealed by newWmutant (Wct) in mice
Authors: Loutit J. F. , Cattanach B. M. 
Published: September 2009

SUMMARYA new mutant (Wct) has been identified at theWlocus of the mouse. The homozygote is poorly viable. Whereas the heterozygote (Wct/ +) is only mildly anaemic likeWυ/ +, the double heterozygoteWct+ / +Phis considerably more anaemic thanWυ+ / +Phand it andWsh+ / +Phhave significantly raised leucocyte counts.Wct+ / +Phis also unduly radiosensitive to whole body X-irradiation, 50% dying from haematopoietic failure at a dose of 4·59 ± 0·14 Gy, whereas the median forWct/ + was 6·49 ± 0·28 Gy. Serial blood counts of mice after low- or sub-lethal doses of X-rays revealed significantly more profound depression of counts of both red cells and leucocytes inWct+, and more notably inWct+ / +Ph, than in + / + orWsh/ + (haematologically normal) iso-dosed mice. We conclude that control of haematopoiesis by chromosome 5 is not confined to theWlocus but is shared by the linked genePh(and perhapsRw) and that expression of the change is not limited to the erythron but involves the pluripotent haematopoietic stem cell.
Map and function ofgadmutations inPhysarum polycephalum
Authors: Shinnick T. M. , Anderson R. W. , Holt C. E. 
Published: September 2009

SUMMARYAmoebae and plasmodia are alternate vegetative forms in the life cycle of the acellular slime mouldPhysarum polycephalum. Haploid amoebae carrying heterothallic alleles of thematA(ormt) locus ordinarily form plasmodia only by crossing, but occasionally give rise to mutants that form plasmodia by selfing as well as by crossing. Twelve independently isolated mutants of this type have been studied. Eight carry mutations (termedgador greater asexual differentiation mutations) within approximately 0·2 map units ofmatA. Another mutation (gad-12) is linked neither tomatAnor to any of 9 other markers tested. The remaining three mutations are linked tomatAand map as follows:matA–0·5 units –gad-4–4 units –gad-6– 8 units –gad-11. One mutation,gad-11, has been tested in strains carrying each of the fivematAalleles (matAl, 2, 3, 4, andh) available in a common genetic background; the mutation is expressed with all five alleles. The mutationnpfF1(formerlyaptA1), which was isolated as a suppressor of selfing in Colonia (matAh) amoebae, suppresses the action of each of the 12gadmutations. The similarly isolated mutationnpfA1is also epistatic to eight of the mutations, but permits selfing withgad-5, 6, 12and13. For double mutant strains containinggad-12andgad-1, 2, 4, 6or11, the selfing behaviour of each double mutant differs from that of either single mutant. Mixtures ofgad−npfF1withgad+npf+amoebae readily form plasmodia, a result suggesting thatgadmutations are dominant or semi-dominant. We conclude that the commitment of a cell to differentiate into a plasmodium is under the control of a complex group of genes linked tomatA.
Quantitative genetics and the evolution of ontogeny: I. Ontogenetic changes in quantitative genetic variance components in randombred mice
Authors: Cheverud James M. , Leamy Larry J. , Atchley William R. , Rutledge J. J. 
Published: September 2009

SUMMARYWe report the results of an ontogenetic analysis of quantitative genetic variance components with two replicates drawn from the randombred ICR strain of mice. A total of 432 mice from 108 full-sib families raised in a cross-fostering design were used to estimate direct effects heritability, maternal effects, and environmental effects for weight, head length, trunk length, trunk circumference, and tail length at 17, 24, 31, 38, 45, 52, 59, and 66 days of age. There was no significant difference in heritability between the replicates. Heritabilities either stayed more or less constant with age at about 0·30 (weight, trunk length, trunk circumference) or increased slightly with age (head length, tail length). Maternal effects decreased with age from a maximum of about 0·50 at weaning to about 0·15 at age 66 when growth was nearly complete. Environmental effects increased in relative importance during ontogeny.
Oocyte specific regulation of PGK-1 isozyme activity in female germ cells of the mouse
Authors: McMahon Andy 
Published: September 2009

SUMMARYThe expression of electrophoretic variant forms of the X-linked enzyme phosphoglycerate kinase (PGK-1) was examined during the ontogeny of the female germ-line followingX-chromosome reactivation. Non-growing oocytes from foetal and neonatal ovaries of heterozygous females show a higher PGK-1A isozyme activity, a reflection of prior non-randomX-inactivation favouring activity of theX-chromosome carrying thePgk-1aallele andXceclocus. On oocyte growth, the total PGK-1 enzyme activity increases 40–50 fold and the pattern of PGK-1 isozyme expression changes giving an electrophoretic pattern now skewed in favour of the PGK-1B isozymic form. Activity of the PGK-1B isozyme exceeds that of PGK-1A in all growing oocytes with a total activity greater than 0·075 nmol h−1oocyte−1. Mice homozygous for eitherPgk-1allele show similar PGK-1 specific activities in somatic tissues where oneX-chromosome is active, but oocytes ofPgk-lbhomozygotes show a higher specific activity compared to those ofPgk-1ahomozygotes. Thus increased activity of the PGK-1B isozyme relative to the PGK-1A isozyme is specific to growing oocytes.
Nonprogressive sperm motility is characteristic of most completethaplotypes in the mouse
Authors: Olds-Clarke Patricia 
Published: September 2009

SUMMARYEpididymal sperm from male mice carryingtw32(t12complementation group) exhibit a peculiar nonprogressive type of motility called ‘dancing’; sperm from congenie wild-type mice do not. To determine whether this effect was unique totw32or common to all t haplotypes, sperm from mice carrying otherthaplotypes were examined. A male was considered to have nonprogressive sperm if more than 20% of the motile sperm had nonprogressive trajectories. The mean percentage of nonprogressive but motile sperm for 33 wild-type and Brachyury males of various genetic backgrounds was 4. All males carryingtw12(tw1complementation group),tw5ortw73, and 56% of males carryingt0ortLub1had nonprogressive motile sperm. Five per cent of males carryingtchromatin or a deletion in the proximal (to the centromere) half of thetcomplex had nonprogressive motile sperm, but all males carryingtchromatin in the distal half of thetcomplex had nonprogressive motile sperm. These observations suggest that the factor or factors causing nonprogressive sperm motility may be common to all completethaplotypes, and located in the distal region of thetcomplex.
Effects of linkage on response to directional selection from new mutations
Authors: Keightley P. D. , Hill W. G. 
Published: September 2009

SUMMARYThe influence of linkage on the rates of response to continued directional selection of quantitative traits deriving from variation contributed by new mutations in finite populations is investigated. Mutant genes are assumed to have additive effects which are randomly sampled from a symmetric distribution, and to be randomly located on the chromosome. Results were obtained by Monte Carlo simulation.The expected steady rate of response, when variability from new mutations is balanced by that lost by drift and selection, is reduced the tighter the linkage, but the reduction is small unless there are few, short chromosomes. For a given rate of new mutational variance per haploid chromosome set per generation, greater effects of linkage are obtained in large than in small populations, because more mutants segregate. The response and influence of linkage are essentially the same whether the new variance is due to many genes of small effect or few of large effect.The variability of response between replicates and generations was investigated, and the contribution to this of new mutants or recombination of existing mutants compared. Usually most genetic variability was due to the occurrence of a new favourable mutant of large effect.
A new type of plasmodium formation inPhysarum polycephalum
Authors: Anderson Roger W. , Truitt Christine L. 
Published: September 2009

SUMMARYHaploid amoebae ofPhysarum polycephalummay form plasmodia sexually by ‘crossing’, which involves cellular and nuclear fusion, or asexually by ‘selfing’, which occurs without nuclear fusion. In most amoebal strains, selfing is seen in clonal cultures only at very low frequency. In the present study, we have shown that selfing occurs at a similarly low frequency in mixtures of crossing-incompatible amoebae, but is stimulated in crossing-compatible mixtures. In certain compatible mixtures involving mutant strains, where crossing is temperature-sensitive, selfing may be stimulated even at a temperature that largely or wholly abolishes crossing. The extent to which selfing is stimulated appears to be influenced bymatB, a locus which is known to affect the frequency of amoebal fusion. We have failed to detect any filter-transmissible factor that might be responsible for the effects we have observed. We suggest a sequence of events that might bring about ‘stimulated selfing’ as a consequence of abortive crossing.
Identification of a male determinant on the X chromosome of housefly (Musca domestica L.) populations in South-East England
Authors: Denholm I. , Franco M. G. , Rubini P. G. , Vecchi M. 
Published: September 2009

SUMMARYHouseflies collected from eight pig-breeding farms were used to investigate the nature of sex determinants in fly populations of South-East England. Earlier observations had shown that their sex determination mechanism was not of the standard (XX females, XY males) type.Most flies of both sexes were XX; the male determining Y chromosome of standard populations was rare. Test-crosses to females of standard multimarked strains and crosses using aneuploid (OX) flies identified two dominant male determinants, one on autosome 3 (M III) and another on the X chromosome (Xm), and provided the first demonstration in this species of an active involvement of the X chromosome in sex determination. A small secondary constriction on X appeared to indicate reliably the presence of Xm. Most individuals in field populations were Xm homozygotes, implying the presence of an unlocated female determinant F,† epistatic to Xm and M III.M III was less common and differed in frequency between samples. Its increased frequency in a strain selected in the laboratory with the pyrethroid insecticide permethrin might be due either to genetic drift, or to linkage between M III and a gene on autosome 3 that confers resistance to pyrethroids in houseflies.
Rec-mediated recombinational activity of two adjacent Chi elements in bacteriophage lambda
Authors: Yagil Ezra , Shtromas Inna 
Published: September 2009

SummaryChi is a sequence of eight nucleotide pairs which stimulaterecBC-mediated recombination (Smith, 1983a, b). The effect of two linked Chis onrecBC-mediated recombination was tested in bacteriophage lambda. It was noticed that the Chi element located on the right side of the phage chromosome is epistatic on the other Chi. These findings support a model proposed by Stahlet al.(1983) which suggests that the recombination machinery moves unidirectionaly in the phage chromosome from right to left. The results also suggest that in the presence of more than one Chi only the rightmost one stimulates recombination.