bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural selection and colour blindness: fresh data on Indian castes
Authors: Malhotra K. C. 
Published: September 2009

SUMMARYIncidence of colourblindness among 3325 males belonging to 21 endogamous Dhangar castes (shepherds) of Maharashtra, India, has been reported. Of the 21 castes studied 5 lacked the gene for colourblindness, while in other groups it varied from 1% to 55%, with a series average of 2·65%. The low incidence of observed colourblindness has been discussed in the light of the nomadic way of the life of some of the Dhangar castes. The results have been compared with other nomadic populations of Maharashtra. The results, in general, are compatible with the Post and Pickford's hypothesis of differential selection for colourblindness.
Immunogenetics of a sheep (Ovis aries) serum antigen
Authors: Iannelli Domenico 
Published: September 2009

SUMMARYAn allotypic specificity (A1) of sheep serum is described. The antigenic determinant is located on a low molecular weight glycoprotein which has its isoelectric point at pH 5 and is capable of interacting with the lectin concanavalin A.Family studies showed that the allotype is inherited in a simple Mendelian manner.
Meiosis inSchizophyllum commune: premeiotic DNA replication and meiotic synchrony induced with hydroxyurea
Authors: Carmi Pheya , Koltin Y. , Stamberg Judith 
Published: September 2009

SUMMARYHydroxyurea (HU) effectively inhibits meiosis inSchizophyllum. The predominant cytological stage in inhibited fruit bodies is fusion. The inhibition is reversible and makes possible synchronization of a naturally nonsynchronous system. Microphotometric determinations of the DNA content in prefusion nuclei treated with HU suggest that premeiotic DNA replication occurs in prefusion nuclei. Synaptinemal complexes are not completed in HU-treated nuclei, suggesting that this event is dependent on premeiotic DNA replication.
On the dispersion of imaginal progenitor cells in theDrosophilablastoderm
Authors: Wyman Robert J. , King David G. 
Published: September 2009

SUMMARYThe number of blastoderm cells inDrosophilawhose descendants form adult structures has frequently been estimated from genetic mosaics. Data from somatic recombination (method I) and gynandromorph (method II) mosaics both yield very low estimates, e.g. about 10–20 progenitor cells for the eye and antenna, wing or leg.In gynandromorphs the mosaic dividing line has a random orientation on the blastoderm. In the 6000 cell blastoderm it should be very unlikely that the mosaic dividing line passes through any small patch of only 10–20 cells. Yet it has been reported that 10–25% of eye/antenna, wing or leg disks in gynandromorphs are mosaic. Thus the frequency of mosaicism data seems to be in contradiction to the progenitor population estimates. Similar discrepancies are found in the data for other adult structures.In this paper we derive a formula for estimating the number of cells in a blastoderm patch from the frequency with which the gynandromorph dividing line passes through it (method III). In a second method (method IV) we use the maximum distances inside the progenitor areas on a fate map to estimate the progenitor patch size. These two estimates agree closely with each other. We find, e.g. that 50–100 cells are in the patches from which the eye/antenna, wing or leg disks derive.We examine a number of possible explanations for why the first two estimates are so much smaller than the last two. The former estimates refer to the number of progenitor cells which actually have descendants in the adult structure; the latter estimates refer to the total patch area in which the progenitor cells sit. With the present information the most reasonable conclusion is that the progenitor cells for the adult structures are dispersed among other cells which have different developmental fates. If confirmed by experiment, this result has many implications for the process of determination.
Cell numbers and cell sizes in organs of mice selected for large and small body size
Authors: Falconer D. S. , Gauld I. K. , Roberts R. C. 
Published: September 2009

SUMMARYCell numbers in four organs of large, control and small mice were estimated by nuclear counts. Average cell mass was estimated from the cell number and the organ weight. The mice were from the selected Q-strain with six replicate lines in each size-group. The organs were lung, liver, spleen and kidney. At 6 weeks of age the large mice had more cells and larger cells than the controls in all organs; the small mice had fewer and smaller cells than the controls. The regression of log cell-number on log-organ weight provides a measure of how much, proportionately, cell number contributes to the differences in organ weight. In the lung and spleen, cell number contributed about 70% of the strain differences in organ weight, cell mass contributing about 30%; in the liver and kidney the relative contributions were about equal, at 50%.Cell counts at different ages from 3 to 15 weeks showed that cell number and cell mass contributed to the increases of organ weights during growth in roughly the same proportions as stated above. From this it is concluded that the main effect of selection for body weight has been to speed up or slow down the normal processes of cellular growth.
The alcohol dehydrogenase polymorphism in populations ofDrosophila melanogaster: 3. Differences in developmental times
Authors: Van Delden W. , Kamping A. 
Published: September 2009

SUMMARYFrom the F2ratios of crosses betweenDrosophila melanogasterstrains homozygous for theAdhF(F) and theAdhs(S) allele it has been concluded that the developmental time ofFFhomozygotes is shorter than that ofSShomozygotes. This difference is found to be reinforced by increasing levels of crowding. A further analysis of developmental times has been performed by the transfer of larvae to agar medium after they have stayed for periods of variable length on regular food. From the percentage of emerging adults it can be concluded thatFFlarvae and, to a lesser extentFSlarvae, either reach their critical weights for pupation earlier thanSSlarvae or possess a lower critical weight. These differences in developmental time influence the course of allele frequencies. Between populations kept on a 2-week transfer schedule and on a 3-week schedule a divergence of allele frequencies is observed, in the former a decrease inSfrequency occurs. The relevance of the observed differences in developmental time for the maintenance of theAdhpolymorphism is discussed for laboratory populations kept on regular food and at varying densities.
A lethal mutation (cab) affecting heart function in the mouse
Authors: Essien Francine B. 
Published: September 2009

SUMMARYA new autosomal recessive gene (cab, ‘cardiac abnormality’), which affects heart differentiation appeared spontaneously in our mouse colony. The affected homozygotes die approximately half a day prior to birth or at term, with the myocardium exhibiting vacuolation and large areas of mesenchyme-like cells. A significant finding in mutant foetuses is the lack of histochemically detectable glycogen.
A note on the symmetry constraints imposed by dominance in multiple locus genetic models
Authors: Slatkin Montgomery 
Published: September 2009

SUMMARYA method is introduced that allows the simplification of the calculation of equilibrium solutions in multiple locus genetic models of a single infinite population. The method can be applied when the number of different fitnesses is equal to or less than one more than the number of independent allelic frequencies. The results are in terms of relationships – the symmetry constraints – between the gametic frequencies that must be satisfied at any boundary or internal equilibrium. The symmetry constraints are independent of the fitness values and of the recombination fractions. This can lead to some understanding of the equilibrium structure of a model when the full equilibrium solution is not obtained and reduces the number of independent variables in the calculations of the full equilibrium solutions. Examples of two locus models with two alleles at each locus and with two alleles at one locus and three at the other are discussed.
The effects of normalizing and disruptive selection on genes for recombination
Authors: Smith J. Maynard 
Published: September 2009

SUMMARYDeterministic simulations have been carried out of populations under normalizing and disruptive selection for a trait determined by genes with additive effects at six loci. In some simulations a pair of alleles at a seventh locus determined the rate of recombination between the seven loci. Normalizing selection with a single optimum, fixed or fluctuating, invariably led to genetic homozygosity. If the optimum fluctuates widely, the approach to homozygosity may be accompanied by a large decline in the mean fitness of the population. Disruptive selection was simulated by having two ‘niches’ with separate optima and separate density-dependent regulation, but with the adult population mating randomly. If the optima are widely separated, this leads to stable polymorphism. Selection produced linkage disequilibrium, normalizing selection causing repulsion and disruptive selection coupling between + and − alleles. This linkage disequilibrium accelerates the phenotypic response to selection, but delays changes in gene frequency. Selection always favoured alleles for low recombination at the expense of alleles for high recombination.
Germ line aberrations associated with a case of hybrid dysgenesis inDrosophila melanogastermales
Authors: Engels William R. 
Published: September 2009

SUMMARYMale sterility, male recombination, and transmission ratio distortion – all examples of a syndrome known as hybrid dysgenesis inDrosophila melanogaster– were found to involve chromosome–cytoplasm interactions. The latter two have temperature optima near 25° and involve pre-meiotic events. In addition, sex ratio distortion, and induction of certain translocations of theXandYchromosomes (but not the autosomes) were found to be part of hybrid dysgenesis. Both are caused by chromosome–cytoplasm interactions with pre-meiotic events playing a crucial role. The results agree with previous data on female sterility in hybrid dysgenesis, which also has cytoplasmic components and premeiotic origins.
Gene for a serum protein on chromosome 9 in the mouse
Authors: Håkansson E. M. , Juneja R. K. , Lundin L.-G. 
Published: September 2009

SUMMARYAn electrophoretic variation in a mouse serum protein moving closely to the vitamin D binding protein is described. The variation is determined by two codominant alleles at one locus with the allele in DBA causing fast mobility and that in C57BL causing slow mobility. This locus is located in the proximal part of chromosome 9, 14·3 cM from thedlocus and 31·9 cM from theBgslocus. The protein has not yet been identified but possible candidates among the serum proteins are discussed.
Complementation reactions of a lethal mouset-haplotype believed to include a deletion
Authors: Lyon Mary F. , Jarvis Susan E. , Sayers Irene , Johnson D. R. 
Published: September 2009

SUMMARYThe lethalt-haplotypes of the mouse fall into several distinct complementation groups, and varying degrees of partial complementation occur when haplotypes from different groups are crossed. The haplotypeth20arose as a mutant from the haplotypet6, and is thought to include a small deletion covering loci near thet-lethals. In this paper the complementarity ofth20was compared with that of its parent haplotypet6.th20showed weaker complementation thant6of the haplotypestw5,tw32andtw1. Hence the loci of these lethals were probably exposed by the deletion inth20. However,th20showed full complementation oftw18and showed full viability in compound with the dominant brachyury allele hairpin-tail,Thp. Therefore, theth20deletion probably does not overlap the presumed deletion inThp, nor extend to the locus of thetw18lethal. The significance of the weak complementation oftw5,tw32andtw1is discussed.
A sex-linked coat-colour mutation in the mouse non-transmissible through the female
Authors: Guenet Jean-Louis 
Published: September 2009

SUMMARYA sex-linked mutation with a phenotype similar to that of an allele of the Mottled series has been discovered in a mosaic male. This mutation can be normally transmitted through the sperm of the original male but not through the oocytes. Several interpretations of this abnormal transmission are discussed.
Path analysis under generalized assortative mating
Authors: Rao D. C. , Morton N. E. , Cloninger C. R. 
Published: September 2009

SUMMARYAssortative mating is generalized to include social homogamy and phenotypic homogamy as two special cases. This generalization, called mixed homogamy, enables tests of hypotheses on the nature of assortment. Cultural inheritance is also extended to include two components: transmitted from parental environments, and non-transmitted sibship environment. Familial correlations are derived for a variety of relationships under mixed homogamy.
A mathematical model of meiotic segregation in trisomics of yeast
Authors: MacMartin Stuart J. , James A. P. 
Published: September 2009

SUMMARYSegregations at five loci on the left arm of chromosome VII and other data from published sources were used to test a new mathematical model of meiotic segregation in trisomics of the yeastSaccharomyces cerevisiae. Results support this model which predicts that non-centromere-linked genes in trivalent complexes segregate at random. The data indicate that bivalent–univalent complexes are infrequent in trisomics and that recombination between all three homologues is frequent in regions close to the centromere. A test of homologue interference produced no evidence that a crossover between two homologues has any influence on the probability that the same two homologues will be involved in an adjacent crossover.
Hybrid dysgenesis inDrosophila melanogaster: the relationship between theP–MandI–Rinteraction systems
Authors: Kidwell Margaret G. 
Published: September 2009

SUMMARYTwo systems of hybrid dysgenesis, theP–Msystem and theI–Rsystem, are characterized by two different specific types of non-reciprocal hybrid sterility referred to, respectively, asGDandSFsterility. In order to determine the relationship between these two systems, strains representative of the four single-system interactive types were crossed in almost all possible combinations and tested for both types of sterility. The results suggest that the two systems are at least partially independent of one another. There are several examples of single strains that contribute the maternal component for interaction in theP–Msystem and contribute the paternal component in theI–Rsystem. Using parents with the potential for the two types of interaction and. appropriate temperature manipulation, bothGDandSFsterility can be manifested in the same hybrid females. In other crosses, a single type of sterility is observed, or none at all, according to the dual designation of the parental strains. The evidence from a number of additional crosses suggests that most strains of this species have the potential for both types of interaction to varying degrees when mated in appropriate combinations. Some theoretical and practical implications of these results are discussed.
Hybrid dysgenesis inDrosophila melanogaster: rules of inheritance of female sterility
Authors: Engels William R. 
Published: September 2009

SUMMARYHybrid dysgenesis has been described as a syndrome of aberrant traits including sterility, male recombination, and mutation, which occurs in some inter-strain hybrids of Drosophila, but only from one of the two reciprocal crosses. In a series of experiments in which hybrids of various pedigrees were tested for sterility, it was found that a case of hybrid dysgenesis could be most easily interpreted as the interaction of two components. One component was found to be a polygenic Mendelian factor linked to each of the major chromosomes of π2, the paternally contributing strain (‘Pstrain’). These chromosomes were capable of causing sterility when inherited from either parent, provided the appropriate maternal component was also inherited. The ability to transmit this maternal component was designated ‘cytotype’ to indicate that it is a property of the entire cell. It was possible to classify nearly all hybrid females as eitherPorMcytotype on the basis of their ability to produce sterile daughters. All daughters of theM-cytotype mothers were susceptible to the sterilizing effects of the π2chromosome, whereas all, or nearly all daughters ofP-cytotype mothers were immune. When more than one of the π2chromosomes were received by daughters ofM-cytotype females, chromosomal interactions could be detected statistically, but the model of independent action remained a useful approximation. Cytotype was shown to be determined by chromosomal factors, but with limited cytoplasmic transmission. This unusual mode of inheritance can be compared with other cases of hybrid dysgenesis where the behaviour resembles that of self-replicating cytoplasmic particles which are dependent on certain chromosomes. The lack of sterility from intra-strain crosses can be explained by the fact that chromosomes capable of causing sterility also induce thePcytotype, and thus prevent sterility in the next generation.
Genetic aspects of fertility differentials in ponderosa pine
Authors: Linhart Yan B. , Mitton J. B. , Bowman D. M. , Sturgeon K. B. , Hamrick J. L. 
Published: September 2009

SUMMARYThere is a strong genetic component to fertility differentials among individuals of ponderosa pine. Prolific cone-producers as a group were markedly different from low cone-producers at the three protein loci which were monitored. The two groups did not differ significantly in age, but trees with high cone production had slower growth rates and smaller diameters than trees with low cone production. To our knowledge, these results provide the first demonstration of fertility differentials associated with specific genes in a woody plant.
A comparison of genetic variability atX-linked and autosomal loci in kangaroos, man andDrosophila
Authors: Cooper D. W. , Johnston P. G. , Vandeberg J. L. , Maynes G. M. , Chew G. K. 
Published: September 2009

SUMMARYThis paper tests the hypothesis that haplodiploidy orXlinkage leads to less genetic variability. Although haplodiploid organisms exhibit a low level of genetic variability the wide variation existing between different diploid organisms implies that factors other than the genetical system could also be responsible. In order to test the hypothesis critically it is necessary to compare the level of genetic variability betweenX-linked and autosomal genes within a closely related group of organisms. For kangaroos, the ascertainment bias forX-linked loci has been removed by assuming the correctness of Ohno's law of conservation of the mammalianX, i.e. that genes found to beX-linked in man can be assumed to beX-linked in kangaroos. For Man andDrosophila, it has been assumed that the percentage of the karyotype which isXchromosome can be used as the expectation for the percentage ofX-linked polymorphisms. No difference between the two classes of loci is evident in kangaroos and man for percentage polymorphism. The data however have confidence limits which would allow autosomal loci to have three times greater percentage polymorphism. InDrosophilathe published data of Prakash show that autosomal loci are polymorphic about twice as frequently as are theirX-linked counterparts. Thus theremaybe a modest reduction in percentage polymorphism as a result ofX-linkage (i.e. haplodiploidy). No reduction in the number of alleles per locus or average heterozygosity at those loci which are polymorphic is evident in kangaroos, man, orDrosophila. More data on moreX-linked enzymes are necessary to establish firmly that there is a real reduction in percentage polymorphism and to estimate its extent. The kangaroo data are incompatible with the hypothesis that a large fraction of the variability is maintained by simple overdominance since overdominance is very unlikely in the quasi-haploid genetical system which results from the paternalXinactivation mode of dosage compensation used by kangaroos. This is the first report on level of enzymic variability in marsupials. 17% of autosomal loci and 18% ofX-linked loci are polymorphic, average heterozygosity is 4% for autosomal and 4% forX-linked loci and number of alleles per locus is 1·25 for autosomal and 1·21 forX-linked loci. These figures are somewhat lower than for eutherian mammals.
Absence of mitochondrial malic enzyme in mice carrying two complementing lethal albino alleles
Authors: Eicher Eva M. , Lewis Susan E. , Turchin Howard A. , Gluecksohn-Waelsch Salome 
Published: September 2009

SUMMARYMitochondrial malic enzyme (MOD-2) was found to be missing in partially complementing genotypes between lethal deletion alleles at the albino locus in Chromosome 7 of the mouse. Since such partial complementers survive to adulthood, the absence of normal mitochondrial malic enzyme is compatible with life; however, the sterility of both females and males may be correlated with this enzyme deficiency. Of the six radiation-induced lethal albino mutations, five includedeletions for theMod-2locus mapping 1 centimorgan distally fromc.Our data indicate that the maximum genetic distance occupied by any of these deletions is 6 centimorgans.
Digynic triploidy in rabbit blastocysts after delayed insemination
Authors: Beatty R. A. , Coulter V. J. 
Published: September 2009

SUMMARYThe origin of triploid (3N) 5½-day blastocysts in rabbits is inferred from the segregation of sex chromosomes and of an autosomal M-marker whose properties are described. 39 triploids and no tetraploids were scored among 1454 chromosomally scored blastocysts. A delay of 8 h between an ovulatory injection and subsequent insemination raised the estimated normal incidence of 0·59% triploid blastocysts to 3·13%. The increase is ascribed primarily to digyny (17 blastocysts), and to diandry probably mediated by dispermy (1 blastocyst). The triploid components of the two 2N/3N mosaics and the one 3N/6N were digynic. Neither superovulation nor insemination of excessive numbers of spermatozoa could be shown to give rise to triploid embryos. The diandric triploid was X Y Y, the first of this constitution apparently reported in the rabbit. There was some evidence that X X Y triploid blastocysts up to 5½-day gestation are more viable than X X X. In the 2N/3N mosaics each component had been entered by one spermatozoon, and the dliploid component could not have been merely a contamination by dliploid maternal somatic cells. In 2N/4N, 2N/4N/8N and 3N/6N mosaics, each polyploid component showed an exact doubling of the marker chromosome constitution of a component of lower ploidy; their origin is ascribed to doubling or redoubling of chromosome number in isolated embryonic cells. With earlier data included, 49·08 (± s.e. 1·96)% of 652 diploid blastocysts were X Y. 460 non-experimental weaned rabbits were all cliploid.
Interaction between the plasmid R6K andEscherichia coliwith defective DNA polymerase I
Authors: Tweats D. J. , Smith J. T. 
Published: September 2009

SUMMARYInitial experiments demonstrated that the plasmid R6K cannot be transferred to or maintained readily in theE. coliDNA polymerase I deficient strain JG138polA1. Results withE. coliMM386polA12(R6K), which has a temperature sensitive polymerase I enzyme, showed cell division becomes abnormal when the polymerase I enzyme of the host bacteria is inactivated at the restrictive temperature. Under conditions of polymerase I deficiency, R6K replication, as measured by monitoring R-factor-mediated β-lactamase activity, also becomes abnormal with the loss of multiple R6K copies per cell and the apparent maintenance of a single R-factor copy per cell.