bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECTS OF B, K10, AND AR CHROMOSOMES ON THE RESISTANCE OF MAIZE TO VIRAL INFECTION
Authors: McGirr Scott C , Endrizzi J E 
Published: April 2021

ABSTRACT
Studies were conducted to determine if accessory (B) chromosomes, the abnormal tenth (K10) chromosome or the aberrant ratio (AR) phenomenon of maize (Zea mays L.) affect the resistance of the plants to viral infection. Genetically similar stocks of maize with and without these elements were compared to determine what effect they would have on the plants response to Brome Mosaic Virus (BMV), Maize Dwarf Mosaic Virus (MDMV), Wheat Streak Mosaic Virus (WSMV) and Barley Stripe Mosaic Virus (BSMV).—The test results with BSMV were not found to be conclusive. With BMV and MDMV, neither the B orK10 chromosomes were found to alter infections; however, these chromosomes were found to affect the resistance of the plants to WSMV infection. The B chromosomes were found to delay the onset of leaf necrosis by 15%, while the K10 chromosome was found to increase the susceptibility to necrosis by 100%. The AR phenomenon was not found to alter the resistance of maize to BMV infection. However, it was found to increase the susceptibility of maize to MDMV infection by 36% and to decrease the susceptibility of maize to WSMV infection by 92%.
THE EVOLUTION OF CONTINUOUS VARIATION. III. JOINT TRANSMISSION OF GENOTYPE, PHENOTYPE AND ENVIRONMENT
Authors: Cavalli-Sforza L L , Feldman M W 
Published: April 2021

ABSTRACT
Evolutionary models of continuous traits are developed. The models are based on the ideas that: (1) the phenotype is the result of the interaction between genotype and environment; (2) the phenotype is the object of natural selection; (3) not only the genotype but also environmental variables and even phenotypes can be directly transmitted. The phenotype of an offspring at birth is a linear combination of its genotypic value, the phenotypic values of its parents, and their environmental values, all measured on the phenotypic scale. The genetic effects are additive polygenic, and a mutation contribution to the within family variance is admitted.—The values of the offspring phenotype and environment before selection are each linear combinations of these values at birth, the coefficients defining what we call "development." Selection is mostly stabilizing of the Gaussian type, but directional selection is introduced using a Gaussian fitness function with a large variance and a mean far from the current population.—Assortative mating for both phenotype and environment are considered. The analysis in all cases is made by iteration of the means, variances and covariances of the trivariate random variable (genotype, phenotype, environment) whose changes over time completely specify the evolution. In most cases numerical methods are used. The problems of estimating the relative roles of each of the variates in the parents in determining the variates in the offspring are discussed. The major results concern the relative magnitudes of the variances and correlations of the three variates, genotype, phenotype and environment, in a variety of selective, developmental and assorting situations with complex transmission in which G-(genetic), F-(phenotypic), E-(environment) inheritance mechanisms operate jointly. The transmission rules and development patterns (i.e., interactions between phenotype and environment during development) are of major importance in determining qualitative features of the equilibrium distribution.
GENETIC DISSECTION OF CLONALLY INHERITED GENOMES OF POECILIOPSIS. I. LINKAGE ANALYSIS AND PRELIMINARY ASSESSMENT OF DELETERIOUS GENE LOADS
Authors: Leslie James F , Vrijenhoek Robert C 
Published: April 2021

ABSTRACT
Theoretical considerations suggest that a high load of deleterious mutations should accumulate in asexual genomes. An ideal system for testing this hypothesis occurs in the hybrid all-female fish Poeciliopsis monacha-lucida. The hybrid genotype is retained between generations by an oogenetic process that transmits only a nonrecombinant haploid monacha genome to their ova. The hybrid genotype is re-established in nature by fertilization of these monacha eggs with sperm from a sexual species, P. lucida. The unique reproductive mechanism of these hybrids allows the genetic dissection of the clonal monacha genome by forced matings with males of P. monacha. The resultant F1 hybrids and their backcross progeny were examined to determine the amount and kinds of genetic changes that might have occurred in two clonal monacha genomes.—Using six allozyme markers, four similar linkage groups were identified in each clonal genome. Segregation and assortment at these loci revealed no apparent differences between monacha genomes from sexually and clonally reproducing species. Mortality of F1 and backcross progeny revealed differences between the two clonal genomes, suggesting that deleterious genes may accumulate in genomes sheltered from recombination.
EFFECTS OF MARKER CHROMOSOMES ON RELATIVE VIABILITY
Authors: Cockerham C Clark , Mukai Terumi 
Published: April 2021

ABSTRACT
Viability relative to Cy/Pm as a standard was studied in Drosophila melanogaster. One experiment, E1, consisted of progeny from eleven distinct 7 x 7 factorial mating designs with reciprocals for second chromosomes extracted from a natural population. The other experiment, E2, consisted of two distinct sets of heterozygotes with reciprocals and corresponding homozygotes. It was established from E1 that there are little to no synergistic effects among different genotypes in a vial and that Cy and Pm heterozygotes vary almost as much as would be expected if one chromosome were held constant for wild-type heterozygotes. In wild-type heterozygotes, variances were estimated to be 0.0099 for average chromosomal effects, 0.0054 for interactions of chromosomes, 0.0021 for maternal effects, 0.0079 for paternal effects, and -0.0010 for the remaining interaction effects, all being significantly different from zero except the last. The variances of Cy and Pm heterozygotes, covariance of Cy and Pm heterozygotes, and covariances of Cy and Pm heterozygotes with wild-type heterozygotes, as well as the comparable statistics available in E2, all showed a large paternal component of variance and a smaller maternal component of variance, both unexpected results.—From E2 the variance of homozygotes, excluding error variance, was estimated to be 0.0149, and the covariances of homozygotes with wild-type heterozygotes to be 0.0056 for maternally derived chromosomes common and 0.0126 for paternally derived chromosomes common, again showing the larger paternal than maternal influence. The average genetic regression of heterozygotes on homozygotes of 0.61 was reduced only slightly to 0.56 by correcting for maternal and paternal variances. These genetic regressions, generally utilized as estimators of the average degree of dominance, are larger than any previously reported.—Differential meiotic drive in Cy and Pm parents was shown to be compatible with the large paternal and maternal variances, but other causes cannot be ruled out.—Approximations were developed for translating various variances, covariances, and regressions between single- and double-marker experiments, assuming that marker chromosomes behave as typical wild-type chromosomes in one case and assuming a (partially) recessive model with the population in mutation selection balance in another case. Various features, particularly the estimation of dominance, were compared and discussed between the two cases.
LACK OF SPONTANEOUS SISTER CHROMATID EXCHANGES IN SOMATIC CELLS OF DROSOPHILA MELANOGASTER
Authors: Gatti M , Santini G , Pimpinelli S , Olivieri G 
Published: April 2021

ABSTRACT
Neural ganglia of wild type third-instar larvae of Drosophila melanogasier were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 μg/ml) . Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs) . At the lowest concentration of BUdR (1 μg/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9 and 27 μg/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogasier, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.—In order to find an alternative way of measuring the frequency of SCEs in Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(I)TR94-2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(I)TR94-2 and rod chromosomes.
FREQUENCY-DEPENDENT SELECTION AT THE LAP LOCUS IN DROSOPHILA MELANOGASTER
Authors: Nassar R 
Published: April 2021

ABSTRACT
Results of fitness estimates for the Lap locus in Drosophila melanogaster revealed that under crowded media conditions gene frequency equilibrium was maintained by frequency-dependent selection. Evidence was obtained that indicated that mating and egg-to-adult viability were frequency dependent.
EXPERIMENTAL POPULATION GENETICS OF MEIOTIC DRIVE SYSTEMS II. ACCUMULATION OF GENETIC MODIFIERS OF SEGREGATION DISTORTER (SD) IN LABORATORY POPULATIONS
Authors: Lyttle Terrence W 
Published: April 2021

ABSTRACT
The accumulation of modifiers of the meiotic-drive locus Segregation Distorter (SD) in Drosophila melanogaster was monitored by measuring the changes in the mean and variance of drive strength (in terms of "make" value) that occur in laboratory populations when SD and SD+ chromosomes are in direct competition. The particular SD lines used are T(Y;2),SD translocations showing pseudo-Y drive. Four sets of population cages were analyzed. Two sets were monitored for changes in SD fitness and drive strength (presumed to be positively correlated) and analyzed for the presence of autosomal dominant or X-linked modifiers after long periods of time. The remaining two sets were made up of cages either made isogenic or variable for background genetic material, and these were used to test whether the rate of accumulation of modifiers was dependent on initial genetic variability.—Contrary to previous studies in which most suppression of SD action could apparently be attributed to a few dominantly acting modifiers of large effect, the conclusion here is that laboratory populations that are initially free of such major dominant loci evolve to suppress SD action by accumulating polygenic, recessive modifiers, each of small effect, and that much of the required genetic variability can be generated de novo by mutation. Possible explanations for these seemingly incompatible results and the evolutionary implications for SD are considered.
A PROBABILITY MODEL FOR EVALUATING THE RANDOMNESS OF THE ASSORTMENT OF CHROMOSOMES DURING SOMATIC REDUCTION
Authors: Geng Shu , Dvorak Jan , Schneeman Paul 
Published: April 2021

ABSTRACT
Pollen mother cells with reduced numbers of chromosomes have been observed in wheat, its hybrid derivatives and amphiploids. Models are presented here for calculating the exact probability of the occurrence of any particular combination of single chromosomes and chromosome pairs in any reduced cell. Hence, it is possible to evaluate randomness of chromosome assortment in somatic reduction. Several sets of data reported by other investigators on somatic reduction in Triticum are analyzed, and we conclude that in those instances chromosomes assort at random.
RESPONSES TO SELECTION FOR BODY WEIGHT IN DESCENDANTS OF X-IRRADIATED RATS
Authors: Gianola Daniel , Chapman A B , Rutledge J J 
Published: April 2021

ABSTRACT
The effectiveness of selection for high and low body weight at six weeks of age was studied in descendants of X-irradiated (R) and nonirradiated (C) inbred rats. There were two replicates of each of the direction of selection irradiation treatments. In C lines, there were no consistent responses to selection, probably due to a low level of genetic variability. In R rats, selection was effective only for decreased body weight. The results of this experiment do not suggest the use of irradiation combined with selection as a means of enhancing responses to selection in animals.
VARIANCE IN QUANTITATIVE TRAITS DUE TO LINKED DOMINANT GENES AND VARIANCE IN HETEROZYGOSITY IN SMALL POPULATIONS
Authors: Avery P J , Hill W G 
Published: April 2021

ABSTRACT
The influence of small population size (N) on the genetic variance within and between randomly bred unselected lines, with selfing permitted, is investigated for a model of a quantitative trait determined by linked genes that show dominance within loci but are additive over loci. Formulae for within-line variance include terms in linkage disequilibrum, which occurs by chance in the lines and these are evaluated in terms of N, map length and gene number. —The expected variance within lines is increased by this disequilibrium, quite substantially if there are many loci, with most of the increase being between or within full-sib families and almost no change expected between half-sib families or in the covariance of offspring and parent. If all loci are unlinked, there is no increase in variance within full-sib families. The variance between lines is little affected by disequilibrum generated by chance.— Expressions for the variance between individuals in heterozygosity over the whole genome are special cases of those for the variance due to linked dominated genes, and formulae are given and evaluated. The coefficient of variation of heterozygosity is at least 1/√3N and can be much higher for species with few chromosomes.
THE DYNAMICS OF FINITE HAPLOID POPULATIONS WITH OVERLAPPING GENERATIONS. I. MOMENTS, FIXATION PROBABILITIES AND STATIONARY DISTRIBUTIONS
Authors: Emigh Ted H 
Published: April 2021

ABSTRACT
Much of the work on finite populations with overlapping generations has been limited to deriving effective population numbers with the tacit assumption that the dynamics of the population will be similar to a population with nonoverlapping generations and the appropriate population number. In this paper, some exact and approximate results will be presented on the behavior of the first two moments of the gene frequencies. The probability of fixation of a neutral gene is found equal to the initial average reproductive value of the gene, and the means and covariances of the stable distribution with mutation in both directions are found by a simple extension of the values found by assuming nonoverlapping generations.
POPULATION GENETICS OF DROSOPHILA AMYLASE. II. GEOGRAPHIC PATTERNS IN D. PSEUDOOBSCURA
Authors: Powell Jeffrey R 
Published: April 2021

ABSTRACT
Morph frequencies of three related polymorphisms were determined in ten natural populations of Drosophila pseudoobscura. They are the well-known inversion polymorphism of the third chromosome and the polymorphism for a-amylase produced by the structural gene Amy (which resides on the third chromosome). The third polymorphism was for tissue-specific expression of Amy in adult midguts; a total of 13 different patterns of activity have been observed. The preceding paper (POWELL and LICHTENFELS 1979) reports evidence that the variation in Amy expression is under polygenic control. Here we show that the polymorphism for midgut activity patterns occurs in natural populations and is not an artifact of laboratory rearing.—From population to population, Amy allele freuencies and frequencies of inversions belonging to different phylads vary coordinately. The geographic variation in α-amylase midgut activity patterns is uncorrelated with that for the other two types of polymorphisms. Furthermore, no correlation was detected between activity pattern(s) and Amy genotype(s) when both were assayed in the same individual.——These results imply that whatever the evolutionary-ecological forces are that control frequencies of the structural gene variants, they are not the same factors that control the frequencies of polymorphic genetic factors responsible for the tissue-specific expression of the enzyme.
A MODEL ALLOWING CONTINUOUS VARIATION IN ELECTROPHORETIC MOBILITY OF NEUTRAL ALLELES
Authors: Cobbs Gary 
Published: April 2021

ABSTRACT
The infinite-sites model with no recombination is extended to include mutations that affect electrophoretic mobility. The model allows the effect of a single-site mutation to have a continuous effect on mobility. Formulae are obtained for the variance of electrophoretic mobility of alleles after an arbitrary length of time. A special case of the general model is the case of stepwise production of neutral alleles with an arbitrary number of steps.
GENETIC MAPPING OF THE CODING REGIONS FOR THREE HEAT-SHOCK PROTEINS IN DROSOPHILA MELANOGASTER
Authors: Peterson Nancy S , Moller Galina , Mitchell Herschel K 
Published: April 2021

ABSTRACT
We describe variants of three heat-shock proteins of Drosophilg melanogaster and their use to map the chromosome regions that contain the coding sequences for these proteins. All three map to a region on chromosome 3L that includes only one heat-shock puff, designated as 67B. The results imply that the genes coding for at least three heat-shock proteins are included within the 67B region.
MATHEMATICAL COMPARISON OF HOMOLOGOUS AND HOMOEOLOGOUS CHROMOSOME CONFIGURATIONS AND THE MODE OF ACTION OF THE GENES REGULATING PAIRING IN WHEAT
Authors: Driscoll C J 
Published: April 2021

ABSTRACT
Analyses of frequencies of chromosome configurations in wheat and wheat hybrids are extended to include data from hybrids of three chromosome-pairing mutants of wheat with Aegilops variabilis and from autotetraploid Triticum monococcum. These data confirm and extend the theory proposed by DRISCOLL, BIELIG and DARVEY (1979). Homoeologous and homologous chromososme pairing are fundamentally identical. The mode of action of the genes regulating pairing in wheat involves either physical alteration in thr chromosomes themselves or changes in an enzyme system that monitors pairing.
TWO MUTATORS AND THEIR SUPPRESSORS IN DROSOPHILA ANANASSAE
Authors: Hinton Claude W 
Published: April 2021

ABSTRACT
Assays of seven mutant stocks exposed a ten-fold range in spontaneous Minute mutation frequencies. Genetic analysis of the difference between the px (0.0006 Minutes) and bri (0.0042 Minutes) stocks revealed that each of these stocks lacks one of two complementary, autosomally transmitted, maternally expressed, dominant suppressors of a dominant 3-linked mutator present in the bri stock. Analysis of the ca; stw stock (0.0013 Minutes) with respect to the former two indicated the presence of the autosomal suppressor functions in addition to a maternally expressed, extrachromosomally transmitted, suppressor of a paternal chromosome-breaking mutator, which is also extra-chromosomally transmitted. The lesions induced by tlie two mutators in male carriers are probably different, but bsth kinds are subject to modification by the maternal suppressors soon after fertilization. The existence of these diverse controls of mutability is viewed as confirmation of STURTEVANT'S (1937) argument that natural selection invokes a variety of devices to minimize mutation rates while retaining mutational potential.
ORGANIZATION OF THE CHORION GENES OF BOMBYX MORI, A MULTIGENE FAMILY. II. PARTIAL LOCALIZATION OF THREE GENE CLUSTERS
Authors: Goldsmith Marian R , Clermont-Rattner Eileen 
Published: April 2021

ABSTRACT
Chorion genes of the inbred stock Ascoli have been localized to three linked clusters by analysis of testcross progeny. Electrophoretic variants screened by isoelectric focusing served as markers. The clusters are designated Ch 1, Ch 2, and Ch 3. The gene order is Ch 1-Ch 2-Ch 3-Y, with relative map distances of approximately 0.4 m.u. for Ch 1-2, 3.3 ± 0.9 m.u. for Ch 2-3, and 21 m.u. for Ch 3-Y. In a separate testcross using different markers, two chorion regions were localized 2.3 mu. and 3.1 mu. from p. These markers could not be assigned to Ch 1, 2, or 3 because there is at present no test for allelism in this system.
A STUDY OF ENZYME ACTIVITIES IN A DOSAGE SERIES OF THE LONG ARM OF CHROMOSOME ONE IN MAIZE
Authors: Birchler James A 
Published: April 2021

ABSTRACT
The enzyme activity levels of alcohol, malate, isocitrate, glucose-6-phosphate and 6-phosphogluconate dehydrogenases were determined in mature maize scutella in a series of one to four doses of the long arm of chromosome 1, produced by the B-A translocation 1La. Although the Adh structural locus was varied, ADH levels did not exhibit a gene-dosage effect. The levels of GGPDH, GPGDH and IDH were negatively correlated with the dosage of 1L. MDH was unresponsive. The esterase-8 enzyme, whose structural locus was demonstrated to be elsewhere in the genome, was also negatively correlated with 1L dosage. The portion of the B chromosome involved in the translocation was shown to have no effect on the enzyme levels. Measurements of cell size and hydrolysable DNA per mg dry weight revealed no change in the number of cells through the one, two and three dose series. The topic of enzyme alterations in aneuploids is reviewed.