bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXAMINATION OF ALLELIC VARIATION AT THE HEXOKINASE LOCI OF DROSOPHILA PSEUDOOBSCURA AND D. PERSIMILIS BY DIFFERENT METHODS
Authors: Beckenbach Andrew T , Prakash Satya 
Published: April 2021

ABSTRACT
Recently a number of electrophoretic techniques have been applied to reveal the presence of additional genetic variation among the electrophoretic mobility classes of the highly polymorphic xanthine dehydrogenase (XDH) and esterase-5 (est-5) loci. We examined the hexokinase loci of Drosophila pseudoobscura and D. persimilis using a variety of techniques to determine whether further allelic variation could be revealed for these much less polymorphic loci and to analyze the nature of the known variation at the hexokinase-1 (hex-1) locus. The following studies were conducted: 135 strains of the two species from six localities were examined with buffer pH ranging from 5.5 to 10.0; 40 strains of D. pseudoobscura and 9 strains of D. persimilis from Mather were studied using starch gel concentrations ranging from 8.5 to 15.5% and were examined for differences in heat stability and reactivity to the thiol reagent p CMSA; strains were also tested for susceptibility to urea denaturation and differences in relative activities. Major findings of the work are: (1) No additional allelic variation could be detected at any of the hexokinase loci by applying these techniques. The finding of abundant hidden genetic variation in XDH and est-5 does not extend to all enzyme loci. (2) Evidence from studies using p CMSA indicates that the hex-1 alleles 0.6, 0.8, 1.0 and 1.2 of the two species form a series of unit charge steps. Since the 0.94 allele of D. persimilis has mobility intermediate between 0.8 and 1.0, it is argued that routine electrophoretic techniques are sensitive to at least some conservative amino acid substitutions. (3) Strong correlations were found at the hex-1locus between low allelic frequency, reduced relative activity and reduced stability to heat and urea denaturation. Since the three sibling species, D. pseudoobscura, D. persimilis and D. miranda, all appear to share a common high frequency allele (1.0) at that locus, these findings are taken as evidence that the observed allelic frequencies are a result of directional selection and mutation, rather than any form of balancing selection.
GENETIC ANALYSIS OF A POPULATION OF TRIBOLIUM. VI. POLYMORPHISM AND DEMOGRAPHIC EQUILIBRIUM
Authors: Moffa A M , Costantino R F 
Published: April 2021

ABSTRACT
Demographic and genetic data of continuously growing populations of Tribolium castaneum initiated with identical age structures but with different frequencies of the unsaturated fatty acid-sensitive allele were collected for 68 weeks.—The life history data provided the following insights: Genotypic differences for total number of offspring were due primarily to larval viability. The total lifetime offspring production of the genotypes predicted a stable polymorphic genetic equilibrium. The genotypic reproductive functions forecast that a stable age structure was not a prerequisite for genetic equilibrium.—Those cultures initially segregating for the unsaturated fatty acid-sensitive allele converged to an equilibrium allele frequency of 0.25 and a genotypic array composed of equal numbers of +/+ and +/cos individuals.—The numbers of larvae, pupae and adults during the first six weeks were quadratic functions of the initial frequency of the sensitive allele. Qualitative age structure changes that followed were similar in all cultures and demographic equilibrium was realized at week 50. The overall demographic pattern during the 68-week study was interpreted in terms of the interactions among the numbers of small larvae, large larvae plus pupae, and adults.
PROPERTIES OF EQUILIBRIA IN MULTI-LOCUS GENETIC SYSTEMS
Authors: Ewens Warren J , Thomson Glenys 
Published: April 2021

ABSTRACT
The classical mathematical theory of population genetics considered, for simplicity, almost exclusively one-locus systems. In the last two decades much work has been done on two-locus and, less frequently, multi-locus systems. This research has usually involved investigating properties of systems with given, and usually rather special, fitness parameters. Real genetic fitness systems are undoubtedly multi-locus and seldom will possess simplifying characteristics. One aim of this paper is to study generalized systems where no special assumptions are made about fitness structure, the number of alleles at each locus, the number of loci involved or the recombination structure between loci. A second aim is to consider marginal properties (often one-locus properties) of complex systems: the fact that many observations involve data from only one locus makes this second aim relevant.
HERITABILITY OF QUASI-CONTINUOUS SKELETAL TRAITS IN A RANDOMBRED POPULATION OF HOUSE MICE
Authors: Self Steven G , Leamy Larry 
Published: April 2021

ABSTRACT
Heritabilities of 11 quasi-continuous skeletal traits were estimated in randombred house mice of three separate ages (1, 3, and 5 months). Three separate methods-regression, maximum likelihood correlation, and Falconer's Method-were used to obtain heritabilities for each of the separate age groups. Significant differences in the incidences of seven of the skeletal traits were found among ages, but they did not affect the heritability estimates, these estimates being pooled over ages. Heritabilities calculated from female parents were consistently higher (by about 13%) than those from male parents, indicating the presence of maternal effects. Mid-parent estimates made by all three methods gave very similar mean levels (0.17 - 0.20). Although low, this level compared favorably with that expected on the basis of previously estimated rates of accumulation of genetic variance. Maternal effects estimated from full sib correlations averaged 0.08.
A MECHANISM OF CHROMOSOMAL REARRANGEMENTS: THE ROLE OF HETEROCHROMATIN AND ECTOPIC JOINING
Authors: Yoon Jong Sik , Richardson R H 
Published: April 2021

ABSTRACT
Clusters of breaks at certain intercalary heterochromatin sites producing chromosomal rearrangements are reported in four endemic species (24 strains) of Hawaiian Drosophila. In laboratory strains of these species we observed some types of changes in chromosome structure that were predicted in our earlier studies (Yoon and Richardson 1976a).—We outline the pseudochromocenter model for the production of chromosomal rearrangements. First, nonhomologous sites that are heterochromatic and contain similar base sequences of highly repetitious DNA join in a chromocenter-like configuration. Second, chromatid exchanges by breakage and reunion occur at the ectopically joined sites. Based on this model, one expects many new chromosomal rerrangements, some of which have been observed and used to differentiate species.—Inversions with identical breakpoints may occur with much greater frequency than previously assumed. Chromosome phylogenies, based on the assumption that inversions are unique events, still would be accurate if the incorporation of an inversion into the karyotype was rare. This would be the case if a rare combination of genes was necessarily contained in the inversion before it was likely to be incorporated into the gamete pool and thereby become a characteristic feature of the species.
X-LINKED AND AUTOSOMAL GENES CONTROLLING MOUSE α-GALACTOSIDASE EXPRESSION
Authors: Lusis Aldons J , West John D 
Published: April 2021

ABSTRACT
Analysis of F2 and backcross animals has confirmed the X-chromosome linkage of Ags, the structural locus for mouse α-galactosidase. The position of Ags has been located in the X chromosome, 9 centimorgans from Mo, and the gene order is centromere-Hq-Bn-Ta-Mo-Ags. A variation in the developmental expression of α-galactosidase activity, inherited as an autosomal trait, has been characterized using recombinant inbred lines of mice. Among certain recombinant inbred lines, the variation appears to segregate as a single major locus.
SEX RATIO DISTORTION CAUSED BY MEIOTIC DRIVE IN A MOSQUITO, Culex pipiens L
Authors: Sweeny Theresa Luine , Barr A Ralph 
Published: April 2021

ABSTRACT
A genetic factor, distorter (d), has been discovered that upsets the normal sex ratio of 1:1 and results in a large excess of males in Culex pipiens. The effect can be explained by a sex-linked, recessive gene. Males homozygous for the gene (Md/md) produce few female offspring; the effect is not due to postzygotic mortality. During the first meiotic division in spermatogenesis, the shortest chromosome pair, which, according to Jost and Laven (1971), is associated with sex determination, can be seen to be abnormal. In a high proportion of spermatocysts, one of the dyads of the shortest bivalent fragments, and the pieces are distributed irregularly to the daughter cells. It is believed that the female-determining chromosomes fragment. This would give rise to an excess of male-determining sperm. The possible usefulness of this factor for control or for experimental purposes is discussed.
GENETIC AND PHENOGENETIC STUDIES ON THE DYNAMIC NATURE OF THE CYTOPLASMIC INHERITANCE SYSTEM IN CULEX PIPIENS
Authors: French Wilbur L 
Published: April 2021

ABSTRACT
Analysis by a progeny test system has permitted the selection for different cytoplasmic sterility factors in two strains of mosquitoes derived from the progeny of a single female. Reciprocal interstrain crosses show full fertility and viability. However, testcrosses to a third cytoplasmic type show highly significant, reproducible differences in the cytoplasmic systems of the selected strains. A direct relationship between teratological growth patterns and the degree of heterozygosity of cytoplasmic factors was observed. In testcrosses, cytoplasmic sterility factors, when selected to homozygosity, produce non-teratological inviable haploid, or exceptional viable gynogenetic diploid larvae. Heterozygosity in the cytoplasmic system in testcrosses produced a broad spectrum of teratological growth patterns related to the degree of heterozygosity of the multiple factors present in the cytoplasm. Formal genetic crosses involving the selected strains show that teratological growth and cytoplasmic sterility, both partial and complete, are inherited through the germ plasm of the maternal parent. This work suggests that the interactions of cytoplasmic factors that result in teratological growth and cytoplasmic sterility may not be restricted to Culex pipiens, where in some cases it is prominent and obvious, but may be a much more general hereditary mechanism of major significance in other eukaryotic animals.
A NEW STRAIN OF DROSOPHILA THAT INHIBITS THE DEVELOPMENT OF SYMPTOMS IN IMAGOES INFECTED WITH SIGMA VIRUS
Authors: Herforth R S 
Published: April 2021

ABSTRACT
A strain of Drosophila melanogaster bearing the mutant gene ebony has been found to slow the development of symptoms (carbon dioxide sensitivity) in adult flies inoculated with sigma virus, a member of the rhabdovirus group. This inhibition is made evident by comparing mean incubation times of the virus in ebony and wild-type (Oregon) flies. The increase in mean incubation time in ebony flies has ranged from about 3 to 8 days, depending on the virus strain, amount of virus injected, and the age of the flies at the time of inoculation. This delay in development of symptoms appears to be due to a dominant autosomal gene, although further work is needed to confirm this. When accumulation of infectious virus after inoculation is compared in ebony and Oregon flies, there seems to be no inhibition of multiplication in ebony at the level of the entire fly. The relationship of this work to current theories on the mechanism of symptom production by sigma virus is discussed.
HETEROZYGOUS EFFECTS ON FITNESS OF EMS-TREATED CHROMOSOMES IN DROSOPHILA MELANOGASTER
Authors: Simmons Michael J , Sheldon Emily W , Crow James F 
Published: April 2021

ABSTRACT
The heterozygous effects on fitness of second chromosomes carrying mutants induced with different doses of EMS were ascertained by monitoring changes in chromosome frequencies over time. These changes were observed in populations in which the treated chromosomes, as well as untreated competitors, remained heterozygous in males generation after generation. This situation was achieved by using a translocation which links the second chromosome to the X chromosome; however, only untranslocated second chromosomes were mutagenized. Chromosomes were classified according to their effects on viability in homozygous condition. A preliminary homozygosis identified completely lethal chromosomes; secondary tests distinguished between drastic (viability index &lt; 0.1) and nondrastic chromosomes. Chromosomes that were nondrastic after treatment were found to reduce the fitness of their heterozygous carriers by 3-5%. The data show that flies homozygous for these chromosomes were about 2.7% less viable per treatment with 1 mm EMS than flies homozygous for untreated chromosomes. By comparing the fitness-depressing effects of nondrastic EMS-induced mutants in heterozygous condition with the corresponding viability-depressing effects measured by Temin, it is apparent that the total fitness effects are several times larger than the viability effects alone. Completely lethal chromosomes derived from the most heavily treated material reduced fitness by 11% in heterozygous condition; approximately half of this reduction was due to the lethal mutations themselves.
REPRODUCTION IN CAGE POPULATIONS OF A POLYMORPHISM REGULARLY OBSERVED IN THE NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER IN FRANCE
Authors: Fleuriet Annie 
Published: April 2021

ABSTRACT
Polymorphism for both alleles of a gene ref(2)P, which is a usual trait of French natural populations of Drosophila melanogaster, can be reproduced in experimental conditions. ref(2)P is a gene for resistance to the hereditary, noncontagious Rhabdovirus α, responsible for CO2 sensitivity in Drosophila melanogaster. The equilibrium frequencies observed in cages are the same as in the wild, whether α virus is present or not. The rapid rate of return to these equilibrium frequencies indicates that strong forces, which remain to be determined, are responsible for the maintenance of this polymorphism.
GENETIC CONTROL AND LINKAGE RELATIONSHIPS AMONG AMINOPEPTIDASES IN MAIZE
Authors: Ott Lila , Scandalios John G 
Published: April 2021

ABSTRACT
Maize aminopeptidase is coded by four genes. Amp1 and Amp2 have been localized to chromosome 1. A three-point cross shows the gene order to be Amp2—15%—Amp1—33%—Adh2(alcohol dehydrogenase). Amp3 and Amp4 assort independently of each other and of chromosome 1 aminopeptidases. Another linkage relationship among the maize genes Amy2 (amylase), Cat1 (catalase), and Amp3 exists, but the chromosome location has yet to be established unequivocally.
POPULATION DYNAMICS OF THE SEGREGATION DISTORTER POLYMORPHISM OF DROSOPHILA MELANOGASTER
Authors: Charlesworth Brian , Hartl Daniel L 
Published: April 2021

ABSTRACT
Two two-locus models of the population dynamics of the segregation distortion (SD) polymorphism of Drosophila melanogaster are described. One model is appropriate for understanding the population genetics of SD in nature, whereas the other is a special case appropriate for understanding an artificial population that has been extensively analysed. The models incorporate the general features of the Sd and Rsp loci which form the core of the SD system. It is shown that the SD polymorphism can be established only when there is sufficiently tight linkage between Sd and Rsp. An approximate treatment, valid for tight linkage, is given of all the equilibria of the system and their stabilities. It is shown that the observed composition of natural and artificial populations with respect to the Sd and Rsp loci is predicted well by the model, provided that restrictions are imposed on the fertilities of certain genotypes. Highly oscillatory paths towards equilibrium are usually to be expected on the basis of this model. The selection pressures on inversions introduced into this system are also investigated.
BISEXUAL HYBRID STERILITY IN DROSOPHILA MELANOGASTER
Authors: Colgan D J , Angus D S 
Published: April 2021

ABSTRACT
A new type of hybrid sterility was investigated in D. melanogaster. Matings between strain 27 males from Para Wirra, South Australia, and Canton-S females produce 70-80% fully sterile male and female progeny. Strain 27 males produce sterile progeny when crossed to females of other geographic origins, but produce fertile progeny when crossed to a second sympatric strain. The sterility is avoided by lower rearing temperatures. Heat shock and tetracycline produce no improvement in the fertility of the hybrids. Normal flies produce sterile progeny when injected with, or fed, homogenates of sterile flies. A combination of maternal and paternal factors may interact to produce sterile hybrids by inhibiting gonad development.
AN APPARENT CONNECTION BETWEEN HISTIDINE, RECOMBINATION, AND REPAIR IN NEUROSPORA
Authors: Newmeyer Dorothy , Schroeder Alice L , Galeazzi Donna R 
Published: April 2021

ABSTRACT
Two mutants of Neurospora crassa, uvs-3 and mei-3, share four properties—UV sensitivity, inhibition by histidine, meiotic blockage when homozygous, and increased duplication instability (due to mitotic crossing over, to deletions or to both). The present paper shows that a third nonallelic mutant, uvs-6, exhibits the same four properties.—Also, the instability of duplications in the absence of any UV-sensitive mutant is increased by the presence of histidine in the growth medium.
UNIPARENTAL INHERITANCE OF MITOCHONDRIAL GENES IN YEAST: DEPENDENCE ON INPUT BIAS OF MITOCHONDRIAL DNA AND PRELIMINARY INVESTIGATIONS OF THE MECHANISM
Authors: Birky C William , Demko Catherine A , Perlman Philip S , Strausberg Robert 
Published: April 2021

ABSTRACT
In Saccharomyces cerevisiae, previous studies on the inheritance of mitochondrial genes controlling antibiotic resistance have shown that some crosses produce a substantial number of uniparental zygotes, which transmit to their diploid progeny mitochondrial alleles from only one parent. In this paper, we show that uniparental zygotes are formed especially when one parent (majority parent) contributes substantially more mitochondrial DNA molecules to the zygote than does the other (minority) parent. Cellular contents of mitochondrial DNA (mtDNA) are increased in these experiments by treatment with cycloheximide, alpha-factor, or the uvs?5 nuclear mutation. In such a biased cross, some zygotes are uniparental for mitochondrial alleles from the majority parent, and the frequency of such zygotes increases with increasing bias. In two- and three-factor crosses, the cap1, ery1, and oli1 loci behave coordinately, rather than independently; minority markers tend to be transmitted or lost as a unit, suggesting that the uniparental mechanism acts on entire mtDNA molecules rather than on individual loci. This rules out the possibility that uniparental inheritance can be explained by the conversion of minority markers to the majority alleles during recombination. Exceptions to the coordinate behavior of different loci can be explained by marker rescue via recombination. Uniparental inheritance is largely independent of the position of buds on the zygote. We conclude that it is due to the failure of minority markers to replicate in some zygotes, possibly involving the rapid enzymatic destruction of such markers. We have considered two general classes of mechanisms: (1) random selection of molecules for replication, as for example by competition for replicating sites on a membrane; and (2) differential marking of mtDNA molecules in the two parents, possibly by modification enzymes, followed by a mechanism that "counts" molecules and replicates only the majority type. These classes of models are distinguished genetically by the fact that the first predicts that the output frequency of a given allele among the progeny of a large number of zygotes will approximately equal the average input frequency of that allele, while the second class predicts that any input bias will be amplified in the output. The data suggest that bias amplification does occur. We hypothesize that maternal inheritance of mitochondrial or chloroplast genes in many organisms may depend upon a biased input of organelle DNA molecules, which usually favors the maternal parent, followed by failure of the minority (paternal) molecules to replicate in many or all zygotes.
ESTIMATION OF LIFE CYCLE COMPONENTS OF SELECTION IN AN EXPERIMENTAL PLANT POPULATION
Authors: Clegg M T , Kahler A L , Allard R W 
Published: April 2021

ABSTRACT
Viability and fertility components of selection associated with linkage blocks marked by four electrophoretically detectable loci were estimated in an experimental population of barley [Composite Cross V (CCV)]. The intensity of selection affecting the distribution of pollen types in the outcross pool was also estimated and comparisons were made between the selective values of genes in the pools of uniting ovules and pollen. The estimates show that selection was intense at various stages of the life cycle and that viability and fertility components often opposed one another. Estimates of viability and fertility components of selection were also extended to the three-locus level. The multilocus estimates reveal large differences in viability and fertility among homozygous genotypes. It is concluded that strong selection operates at all life cycle stages in CCV, although often in differing directions.
ABNORMAL MITOCHONDRIAL GENOMES IN YEAST RESTORED TO RESPIRATORY COMPETENCE
Authors: Oakley K M , Clark-Walker G D 
Published: April 2021

ABSTRACT
When crosses are performed between newly arisen, spontaneous petite mutants of Saccharomyces cerevisiae, respiratory competent (restored) colonies can form. Some of the restored colonies are highly sectored and produce large numbers of petite mutants. The high-frequency petite formation trait is inherited in a non-Mendelian manner, and elimination of mitochondrial DNA from these strains results in the loss of the trait. These results indicate that abnormal mitochondrial genomes are sometimes formed during restoration of respiratory competence. It is hypothesized that these abnormalities result either from recombination between mitochondrial DNA fragments to produce molecules having partial duplications contained on inverted or transposed sequences, or else recombinational "hot spots" have been expanded.
TWO CLOSELY LINKED MUTATIONS IN DROSOPHILA MELANOGASTER THAT ARE LETHAL TO OPPOSITE SEXES AND INTERACT WITH DAUGHTERLESS
Authors: Cline Thomas W 
Published: April 2021

ABSTRACT
A new spontaneous mutation named Sex-lethal, Male-specific #1 (SxlM1) is described that is lethal to males, even in the presence of an Sxl + duplication. Females homozygous for SxlM1 are fully viable. This dominant, male-specific lethal mutation is on the X chromosome approximately 0.007 map units to the right of a previously isolated female-specific mutation, Female-lethal, here renamed Sex-lethal, Female-specific #1 (SxlF1). SxlM1 and SxlF1 are opposite in nearly every respect, particularly with regard to their interaction with the maternal effect of the autosomal mutation, daughterless (da). Females that are homozygous for da produce defective eggs that cannot support female (XX) development. A single dose of SxlM1 enables daughters to survive this da female-specific lethal maternal effect. A duplication of the Sxl locus weakly mimics this action of SxlM1. In contrast, SxlF1 and a deficiency for Sxl, strongly enhance the female-lethal effects of da. The actions of SxlM1 and SxlF1 are explained by a model in which expression of the Sxl locus is essential for females, lethal for males, and under the control of a product of the da locus. It is suggested that SxlM1 is a constitutive mutation at the Sxl locus.