bluuebunny/crossref_metadata_2025_split huggingface dataset:
MULTIPLE MEIOTIC DRIVE SYSTEMS IN THE DROSOPHILA MELANOGASTER MALE
Authors: Miklos George L Gabor , Yanders Armon F , Peacock W J 
Published: January 2021

ABSTRACT
The behaviour of two "meiotic drive" systems, Segregation-Distorter (SD) and the sex chromosome sc4sc8 has been examined in the same meiocyte. It has been found that the two systems interact in a specific way. When the distorting effects of SD and sc4sc8 are against each other, there is no detectable interaction. Each system is apparently oblivious to the presence of the other, gametes being produced according to independence expectations. However when the affected chromosomes are at the same meiotic pole an interaction occurs; the survival probability of the gamete containing both distorted chromosomal products is increased, rather than being decreased by the combined action of two systems.
CLONAL VARIATION IN PARAMECIUM II. A COMPARISON OF STABLE AND UNSTABLE CLONES OF THE SAME SEROTYPE
Authors: Finger Irving , Onorato Fred , Heller Carol , Dilworth Linda 
Published: January 2021

ABSTRACT
Paramecium generally expresses only one antigen on its surface from among an array of antigens. This mutual exclusion of antigens now has been shown in certain instances to be illusory. Unstable clones which will give rise to subclones with new serotypes possess several antigens. Unstable clones, even though they manifest only one serotype, continually manufacture an antigen other than the surface antigen characteristic of the serotype.
EVIDENCE FOR POST-CLEAVAGE FERTILIZATION AMONG MOSAICS IN HABROBRACON JUGLANDIS
Authors: Clark Arnold M , Gould Adair B 
Published: January 2021

ABSTRACT
Habrobracon females homozygous for the mutant ebony produce about 5% mosaic progeny among fertilized eggs. The present experiment demonstrates by means of a test-cross method that in the production of these mosaics only one pronucleus is involved, and that this nucleus cleaves before union of one of its daughter nuclei with the sperm nucleus.
VARIATION ASSOCIATED WITH AN AEGILOPS UMBELLULATA CHROMOSOME SEGMENT INCORPORATED IN WHEAT. II. PEROXIDASE AND LEUCINE AMINOPEPTIDASE ISOZYMES
Authors: Macdonald T , Smith H H 
Published: January 2021

ABSTRACT
Zymograms were analyzed of a number of Triticum aestivum derivatives which incorporated a segment of the Aegilops umbellulata chromosome bearing resistance to leaf rust. Evidence has been presented which suggests that genes involved in the production of two peroxidases and a single peptidase are located on the short arm of wheat chromosome 6B. One peroxidase isozyme, attributed to the presence of the Aegilops segment, was seen in only one of the resistant lines (Transfer) and it was postulated that this peroxidase band was present in a suppressed state in a number of lines. Possible differences in the A and B genomes of T. aestivum and T. dicoccum were discussed.
DEVELOPMENTAL ANALYSIS OF THE WING DISC IN THE MUTANT ENGRAILED OF DROSOPHILA MELANOGASTER
Authors: Garcia-Bellido A , Santamaria P 
Published: January 2021

ABSTRACT
The engrailed (en) mutation leads to the transformation of the posterior structures of the dorsal mesothoracic disc into those characteristic of the anterior region of the same disc. Similar posterior-anterior duplications have been detected in dorsal as well as ventral structures of all the thoracic segments. —Genetic combinations of en with other pattern mutants have shown their synergistic effect on the posterior wing pattern.—A clonal analysis of the en wing disc shows that en affects its development in a characteristic way. The genetic change, by induced mitotic recombination, of en+ into en cells is followed by the corresponding transformation, except when it takes place some cell divisions prior to differentiation.—The en posterior wing disc cells show positive affinities with normal anterior wing disc cells in aggregates.—The mode of action of the en+ locus controlling wing disc development is discussed.
A DOMINANT CONSTITUTIVE phoR MUTATION IN ESCHERICHIA COLI
Authors: Pratt Charles , Gallant Jonathan 
Published: January 2021

ABSTRACT
A dominant constitutive mutation of the phoR locus controlling alkaline phosphatase synthesis in Escherichia coli is described. Its phenotype can be explained by the production of a poisonous subunit of the phoR gene product. The phoR gene product is inferred to consist of at least 3 or 4 subunits.
THE EFFECT OF OXYGEN ON THE FREQUENCY OF SOMATIC RECOMBINATION IN DROSOPHILA MELANOGASTER
Authors: Stauffer H H 
Published: January 2021

ABSTRACT
The influence of oxygen on the frequency of somatic recombination in the yellow singed system on the X chromosome of Drosophila melanogaster was studied under a variety of experimental conditions. Flies raised from egg to adult in atmospheres containing 70-90% oxygen were found to have significantly more mosaic spots on their abdominal tergites than were observed in flies which developed in air. First instar larvae X-rayed in from 0 to 100% oxygen demonstrated the existence of an oxygen effect for somatic recombination in the cells which form the abdominal hypoderm. The mosaic spot counts, beginning with the lowest numbers which were found in flies X-rayed in nitrogen, increased rapidly with rising oxygen tensions until the percentage in air was reached, then leveled off at the higher concentrations. Post-treatment with nitrogen of larvae X-rayed in air or oxygen created a substantially higher number of mosaic spots than were found when larvae, after being similarly irradiated, were instead placed into air or oxygen.
STUDIES ON THE SAL LOCUS IN DROSOPHILA PSEUDOOBSCURA. I. THE BANDING PATTERN OF THE TIP OF SALIVARY CHROMOSOME 3 IN LARVAE HOMOZYGOUS AND HETEROZYGOUS FOR SAL
Authors: Gersh Eileen Sutton 
Published: January 2021

ABSTRACT
In the mutant sal the banding pattern at the tip of chromosome 3 is changed. Certain bands are compacted instead of being partially puffed. In sal+/sal heterozygotes, when the chromosome tips are paired they both show the sal+ pattern or are intermediate; but when unpaired, each shows the pattern characteristic of its own genotype.
BACTERIAL CONJUGATION: AN ANALYSIS OF MIXED RECOMBINANT CLONES
Authors: Lotan Dafna , Yagil Ezra , Bracha Moshe 
Published: January 2021

ABSTRACT
A fraction of recombinant colonies resulting from conjugation is heterogenetic for unselected markers. Constitutivity for alkaline phosphatase synthesis (phoR) is studied as the unselected marker. The frequency of phoR heterogeneity depends on the genetic distance between phoR and the selected marker. Various models are considered which explain the formation of heterogenetic colonies (mixed clones), and experiments are described which test these models. It is concluded that the Hfr fragment can replicate and participate more than once in recombination thus yielding heterogenetic colonies.
SUSCEPTIBILITY TO SPONTANEOUS PNEUMONITIS IN AN INBRED STRAIN OF BEIGE AND SATIN MICE
Authors: Lane Priscilla W , Murphy Edwin D 
Published: January 2021

ABSTRACT
Among mice of strain SB/Le, homozygous for the mutant genes beige (bg), satin (sa), and white-bellied agouti (Aw), 70% developed progressive pneumonitis by 6 months of age. Among backcross offspring from an outcross to C57BL/6J-Aw-J, 49% of homozygous beige and 11% of nonbeige genotypes developed pneumonitis by 6 months of age. The evidence indicates that a specific action of the beige gene increases susceptibility to progressive pneumonitis. Lymphadenopathy, including reticulum cell neoplasms and atypical lymphoproliferative lesions, was observed in high incidence in sa+/sa bg males, suggesting a closer association with satin than with beige. Beige mice show giant lysosomal granules in the leukocytes and pigment dilution closely analogous to the Chediak-Higashi syndrome in man and similar disorders in mink and cattle. Strain SB/Le provides a convenient model in a laboratory animal for study of the increased susceptibility to infection analogous to that of the Chediak-Higashi syndrome.
ALLOZYME GENOTYPE-ENVIRONMENT RELATIONSHIPS. I. VARIATION IN NATURAL POPULATIONS OF DROSOPHILA PACHEA
Authors: Rockwood-Sluss E S , Johnston J S , Heed W B 
Published: January 2021

ABSTRACT
Remarkable geographic and seasonal uniformities in gene and genotype frequencies were found for four enzyme loci. Principal component analysis revealed two patterns of allele frequency changes in three of the allozyme loci (Est-b, Est-c and Acph) and one pattern in the Mdh-d locus. These patterns accounted for 90% to 100% of the variability at these loci. Significant positive correlations were obtained between several of the components and the variability in the non-saponifiable and alkaloid fractions of the senita cactus host plant. The genetic variance within a single locality (Guaymas, Mexico) was as great as the variance between all localities sampled. This is interpreted as a local founder effect. The temporary nature of the rotting cactus breeding site, the delayed maturation and the differential maturation rate of females and males are three factors proposed to cause forced outbreeding and counter the local founder effect. A combination of selection resulting from a direct interaction of the genotype and the environment, in addition to migration, is proposed to maintain the uniform gene frequencies.
GENETIC CONTROL OF MITOCHONDRIA IN PARAMECIUM
Authors: Beisson J , Sainsard A , Adoutte A , Beale G H , Knowles J , Tait A 
Published: January 2021

ABSTRACT
Mitochondrial mutations for resistance to various antibiotics (erythromycin, chloramphenicol, spiramycin, mikamycin) have been obtained in Paramecium aurelia and their properties are reviewed. Using these mitochondrial markers, the interactions between nucleus and mitochondria have been studied in two ways: by microinjection of mitochondria from one stock or species into other stocks and species of P. aurelia and by a genetic study of a nuclear mutation affecting mitochondrial multiplication. Both types of experiments show: (1) that there may exist incompatibility between a given type of mitochondria and the cell into which they are introduced and (2) that through multiplication in the host cell, mitochondrial properties can be modified. The possible basis for incompatibility and host-induced modifications is discussed.
PHYSIOLOGICAL STUDIES OF SALMONELLA HISTIDINE OPERATOR-PROMOTER MUTANTS
Authors: Ely Bert 
Published: January 2021

ABSTRACT
S. typhimurium hisO mutations are cis dominant and trans recessive and occur in a regulatory segment separate from but adjacent to the first structural gene of the histidine operon, hisG. Strains containing hisO mutations singly and in combination with other regulatory mutations were examined for their content of L-histidinol phosphate phosphatase when grown on limiting and on excess L-histidine. HisO mutations classed as "constitutive" (high enzyme levels) or as "promoter-like" (low enzyme levels) cause a variety of sub-phenotypes. A model is proposed that accounts for the phenotypes found as well as for the interspersion of constitutive and promoter-like mutations on the genetic map (Ely, Fankhauser and Hartman 1974). In this model we suggest that the his operator-promoter DNA is a functional unit that assumes alternate conformations including: (a) the classic linear duplex, active in transcription, and (b) a looped structure that is transcriptionally closed and susceptible to the binding of repressor.
GENETIC ANALYSIS OF A DOUBLE MALE STRAIN OF ESCHERICHIA COLI K12
Authors: Falkinham Joseph O , Clark A J 
Published: January 2021

ABSTRACT
The behavior of a double male strain of Escherichia coli K12 has been compared to that of its parents and a primary F' strain carrying F14 in order to determine whether the genome of the double male, responsible for the double origin mode of gene transmission, is composed of one or two linkage groups. F-prime plasmids carrying leu and pyrB and argG and metC have been detected following mating an F- recA - recipient with the double male. Their existence strongly supports the contention that the double male is composed of a single linkage group with two integrated sex factors. Data from acridine orange curing experiments places the frequency of double male cells in the population of growing cells in the two-chromosome configuration as less than one percent. Evidence for a unique origin and terminus of DNA replication deduced by the density labelling and transduction of double male DNA supports the contention that the double male is best considered a cell with a single chromosome carrying two integrated F plasmids.
PHASE-SPECIFIC GENES FOR MACROCONIDIATION IN NEUROSPORA CRASSA
Authors: Selitrennikoff Claude P , Nelson Robert E , Siegel Richard W 
Published: January 2021

ABSTRACT
Two new mutant genes in Neurospora crassa prevent the formation of free macroconidia from proconidial chains. These genes, called conidial separation-1 and conidial separation-2, are phase-specific, playing no role in either the sexual life cycle or other aspects of the asexual life cycle. A cell-wall-associated autolytic activity was found to increase in wild-type cultures at the time of active formation of free conidia from proconidial chains; no such increase was detected in mutant cultures. It appears that the products of these genes are both essential for and unique to macroconidiation.
INDUCTION BY MUTAGENS OF TANDEM GENE DUPLICATIONS IN THE glyS REGION OF THE ESCHERICHIA COLI CHROMOSOME
Authors: Straus Daniel S 
Published: January 2021

ABSTRACT
Four mutagens (ultraviolet light, nitrous acid, the acridine half mustard ICR 372, and niridazole) have been found to increase the frequency of tandem gene duplications in the glyS region of the Escherichia coli chromosome. This result was obtained by quantitating the spontaneous and mutagen-induced reversion frequency of a glycyl-tRNA synthetase (glyS) mutant. Following mutagenesis, as many as 0.2% of the survivors were obszrved to contain duplications in the glyS region. In addition, several classes of stable revertants of the glyS mutant have been identified.
RIBOSOMAL GENE MAGNIFICATION IN DROSOPHILA: A CHROMOSOMAL CHANGE
Authors: Harford A Gayler 
Published: January 2021

ABSTRACT
The sex-linked mutant "bobbed" can undergo a rapid phenotypic reversion during a prescribed series of outcrosses. The experiments reported here distinguish between two general genetic models. The first is that the phenotypic change results from the changing genetic background brought about by the outcrosses. The second is that the phenotypic change results from an alteration of the X chromosome in the germ line. The data support the second model. It is shown that both the bobbed and reverted phenotypes segregate from the same female. In addition, the reverted phenotype maps in or near the proximal heterochromatin of the X chromosome, which is the standard map position of both bobbed and the nucleolus organizer.
LINKAGE DISEQUILIBRIUM IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER
Authors: Langley Charles H , Tobari Yoshiko N , Kojima Ken-Ichi 
Published: January 2021

ABSTRACT
Two large, stable populations (Texas and Japan) of Drosophila melanogaster were surveyed at 21 allozyme loci on the second and third chromosomes and for chromosomal gene arrangements on those two chromosomes. Over 220 independent gametes were sampled from each population. The types and frequencies of the surveyed genetic variation are similar to those observed previously and suggest only slight differentiation among geographically distant populations. Linkage disequilibrium among linked allozymes loci is only slightly, if at all, detectable with these sample sizes. Linkage disequilibrium between linked inversions and allozymes loci is common especially when located in the same arm. These disequilibria appear to be in the same direction for most comparisons in the two population samples. This result is interpreted as evidence of similar selective environments (ecological and genetic) in the two populations. It is also noted that the direction of these linkage disequilibria appears to be oriented with respect to the gene frequencies at the component loci.
GENETIC ANALYSIS IN THE COLONIA STRAIN OF PHYSARUM POLYCEPHALUM: HETEROTHALLIC STRAINS THAT MATE WITH AND ARE PARTIALLY ISOGENIC TO THE COLONIA STRAIN
Authors: Adler Paul N , Holt Charles E 
Published: January 2021

ABSTRACT
Amoebae of the Colonia (CL) strain, which normally produce plasmodia in clones, are shown to cross with mt3 and mt4 amoebae under appropriate conditions. Strains carrying mt3 and mt4 in a CL genetic background were constructed and used in the genetic analysis of mutants isolated in CL.
ESTERASES OF DROSOPHILA II. BIOCHEMICAL STUDIES OF ESTERASE-5 in D. pseudoobscura
Authors: Berger Edward M 
Published: January 2021

ABSTRACT
In vitro enzyme hybridization was carried out with combinations of six allozymic variants of Esterase-5 from Drosophila pseudoobscura. Studies on heat stability and specific activity changes accompanying hybridization were done to examine the possible expression of overdominance at the biochemical level. In 11 of 15 combinations no significant change in specific activity was found following hybridization. In two cases hybridization resulted in a decrease in activity in the mixture, while in two cases esterase activity was elevated. Heat stability studies, in several cases, revealed reduced rates of inactivation in in vitro and in vivo heterozygotes compared with homozygotes. From these and other data a model for the molecular mechanism of heterosis is presented.
THE RESPONSE OF DOPA DECARBOXYLASE ACTIVITY TO VARIATIONS IN GENE DOSAGE IN DROSOPHILA: A POSSIBLE LOCATION OF THE STRUCTURAL GENE
Authors: Hodgetts Ross B 
Published: January 2021

ABSTRACT
A location of the structural gene(s) for dopa decarboxylase (EC 4.1.1.26) is proposed on the basis of enzyme determinations in a set of duplication-bearing aneuploids, which revealed only one dosage-sensitive region in the Drosophila genome. This region lies between 36EF and 37D on the left arm of chromosome 2.
FITNESS OF ALLOZYME VARIANTS IN DROSOPHILA PSEUDOOBSCURA. I. SELECTION AT THE PGM-1 AND ME-2 LOCI
Authors: Marinković Dragoslav , Ayala Francisco J 
Published: January 2021

ABSTRACT
We have studied in Drosophila pseudoobscura the effect of allozyme variation on seven fitness components: female fecundity, egg hatchability, egg-to-adult survival under near-optimal and under competitive conditions, rate of development under near-optimal and under competitive conditions, and mating capacity of males. Three genotypes at each of two loci, Pgm-1 and Me-2, have been studied in various combinations. These two loci are highly polymorphic in natural populations of D. pseudoobscura. Statistically significant differences involving one or more genotypes exist for all components of fitness. No single genotype is best for all fitness components; rather the relative fitnesses of genotypes are reversed when different parameters are considered, or when they are studied in different environmental conditions. Also, the average egg-to-adult survival and rate of development are better when different genotypes are reared together than when they occur in pure culture. Four different modes of selection have been uncovered by our experiments. These forms of selection may account for the persistence of the two allozyme polymorphisms in nature, and for previously observed seasonal fluctuations of the allelic frequencies in natural populations.
GENETIC ORGANIZATION AND ADAPTIVE RESPONSE OF ALLOZYMES TO ECOLOGICAL VARIABLES IN FUNDULUS HETEROCLITUS
Authors: Mitton Jeffry B , Koehn Richard K 
Published: January 2021

ABSTRACT
Populations of Fundulus heteroclitus, (Cyprinodontidae) a widespread coastal marine fish, were studied in control and artificially heated environments on the North Shore of Long Island, New York to determine (1) patterns of variation in biochemical phenotypes and (2) the extent to which this variation reflected adaptation to environmental characteristics.—Variation at three of twelve polymorphic isoenzyme loci from the warm water population was beyond the range of variation among control populations, and resembled those determined for populations living at more southern latitudes. Hence, these differences were interpreted as adaptations to warm environments. Significant differences in allele frequencies and zygotic proportions at ten of twelve isoenzyme loci were found associated with differences in environments, sexes, and/or age classes. These data strongly support the view that protein polymorphisms are adaptive.—Several observations suggested that selection acts upon multilocus phenotypes rather than upon those of single loci. Several di-locus phenotypic distributions were demonstrated to be nonrandom, and those that exhibited similar patterns of dependence over years were postulated to be maintained by selection. Highly heterozygous fish exhibited superior viability when cohorts were compared over successive years.—The consequences of the polygynous mating system in this species for maintaining genetic variation and for allowing rapid evolutionary response to a variable environment are discussed.
POPULATION SIZE AND SELECTION INTENSITY EFFECTS ON LONG-TERM SELECTION RESPONSE IN MICE
Authors: Eisen E J 
Published: January 2021

ABSTRACT
Long-term response to within full-sib family selection for increased postweaning gain was evaluated in lines having different effective population sizes (Ne) and selection intensities (i). Line designations were I4(4), I8(2), I16(2), M4(4), M8(2) and M16(2), where I and M indicate selection of the top 50% and 25%, respectively; 4, 8 and 16 represent the number of parental pairs per replicate and number of replicates is given in parentheses. Realized within full-sib family heritabilities (hR 2) in the first phase of selection (0-14 generations) were larger in 16-pair lines than in 4- and 8-pair lines. In the second phase of selection (&gt;14 generations), hR 2 declined significantly (P&lt;.01) in all lines, and only the I16 and M16 lines had hR 2 values significantly (P&lt;.01) greater than zero. Realized genetic correlations involving number born, 12-day litter weight, weaning weight and six-week weight tended to decline in the second phase of selection. The I16, M16 and control (C16) replicates were crossed in all combinations at generation 14. Crosses were then selected within litters for high postweaning gain. The hR 2 values in the crossbred lines were all larger than those in the second selection phase for M16-1, M16-2 and I16-1, but not for I16-2. Within each Ne level, total response was significantly (P&lt;.01) less for I lines compared with M lines. Total response increased as Ne increased, within each level of i. Relatively small differences in realized i values among Ne lines could not account for this result. The difference in total response among the Ne lines at a given selection intensity may be due to inbreeding depression and a combination of interactions involving "drift" and selection. By crossing replicates of the M lines with the C16 control, the effects of inbreeding depression were removed. Inbreeding depression and genetic drift, as defined herein, were equally important in accounting for differences among Ne lines in total response.
ENZYME POLYMORPHISMS: GENE FREQUENCY DISTRIBUTIONS WITH MUTATION AND SELECTION FOR OPTIMAL ACTIVITY
Authors: Latter B D H 
Published: January 2021

ABSTRACT
Gene frequency distributions observed in large-scale surveys of species of Drosophila are shown to be incompatible with a genetic model involving neutral mutations and genetic drift alone. The data are, however, qualitatively similar to predictions based on an alternative model of natural selection for an optimal level of enzyme activity in addition to drift and mutation. The intensity of selection detected reduces the mean rate of gene substitution to less than one-quarter that expected on the neutral-allele hypothesis.