bluuebunny/crossref_metadata_2025_split huggingface dataset:
CYTOGAMY: AN INDUCIBLE, ALTERNATE PATHWAY OF CONJUGATION IN TETRAHYMENA THERMOPHILA
Authors: Orias Eduardo , Hamilton Eileen P 
Published: April 2021

ABSTRACT
We report the occurrence of cytogainy in Tetrahymena thermophila. By analogy to Paramecium, cytogamy generates exconjugant clones that derive their entire genetic information from a single meiotic product of their cytoplasmic parent. Thus, "instant" whole-genome homozygotes are created. Cytogamy has been induced in every strain of T.thermophila tested, and most of the excytogamous progeny have exhibited high fertility. The high frequency with which cytogamy can be induced by hyperosmotic shock, coupled with the foregoing genetic properties, make this process a practical (and already proven) method for the isolation of recessive mutants in T.thermophila. We also report that the cytogamy-inducing treatment induces other rare abnormalities of genetic transmission, which have not yet been characterized.
A NEW MATING COMPATIBILITY LOCUS IN PHYSARUM POLYCEPHALUM
Authors: Youngman Philip J , Pallotta Dominick J , Hosler Betsy , Struhl Gary , Holt Charles E 
Published: April 2021

ABSTRACT
The rate and extent of plasmodium formation were studied in mating tests involving pairs of largely isogenic amoeba1 strains compatible for matingtype (mt) alleles. A systematic variability was observed: plasmodia formed either rapidly and extensively or slowly and inefficiently. Plasmodium formation was found to be 103- to 104-fold more extensive in "rapid" crosses than in "slow" crosses. A genetic analysis revealed that the variability reflects the influence of a multiallelic compatibility locus that determines mating efficiency. This compatibility locus (designated matB), together with the original mating type locus mt (in this work designated matA), constitute a tetrapolar mating specificity system in Physarum polycephalum.
THE GENETICS OF A SMALL AUTOSOMAL REGION OF DROSOPHILA MELANOGASTER CONTAINING THE STRUCTURAL GENE FOR ALCOHOL DEHYDROGENASE. I. CHARACTERIZATION OF DEFICIENCIES AND MAPPING OF ADH AND VISIBLE MUTATIONS
Authors: Woodruff R C , Ashburner M 
Published: April 2021

ABSTRACT
The position of the structural gene coding for alcohol dehydrogenase (ADH) in Drosophila melanoguster has been shown to be within polytene chromosome bands 35B1 and 35B3, most probably within 35B2. The genetic and cytological properties of twelve deficiencies in polytene chromosome region 34-35 have been characterized, eleven of which include Adh. Also mapped cytogenetically are seven other recessive visible mutant loci. Flies heterozygous for overlapping deficiencies that include both the Adh locus and that for the outspread mutant (osp: a recessive wing phenotype) are homozygous viable and show a complete ADH negative phenotype and strong osp phenotype. These deficiencies probably include two polytene chromosome bands, 35B2 and 35B3.
HYBRID DYSGENESIS IN DROSOPHILA MELANOGASTER: THE BIOLOGY OF FEMALE AND MALE STERILITY
Authors: Engels William R , Preston Christine R 
Published: April 2021

ABSTRACT
High levels of female and male sterility were observed among the hybrids from one of the two reciprocal crosses between a wild strain of D. melanogaster known as π2 and laboratory strains. The sterility, which is part of a common syndrome called hybrid dysgenesis, was found to be associated with the rudimentary condition of one or both of the ovaries or testes. All other tissues, including those of the reproductive system were normal, as were longevity and mating behavior. The morphological details of the sterility closely mimic the agametic condition occurring when germ cells are destroyed by irradiation or by the maternal-effect mutation, grandchildless. We suggest that sterility in hybrid dysgenesis is also caused by failure in the early development of germ cells. There is a thermo-sensitive period beginning at approximately the time of initiation of mitosis among primordial germ cells a few hours before the egg hatches and ending during the early larval stages. Our results suggest that hybrid dysgenesis, which also includes male recombination, mutation and other traits, may be limited to the germ line, and that each of the primordial germ cells develops, or fails to develop, independently of the others. This hypothesis is consistent with the observed frequencies of unilateral and bilateral sterility, with the shape of the thermo-sensitivity curves and with the fact that males are less often sterile than females. The features of this intraspecific hybrid sterility are found to resemble those seen in some interspecific Drosophila hybrids, especially those from the cross D. melanogasfer × D. simulans.
A REFINED MAP OF THE hisG GENE OF SALMONELLA TYPHIMURIUM
Authors: Hoppe I , Johnston H M , Biek D , Roth J R 
Published: April 2021

ABSTRACT
The hisG gene is the most operator-proximal structural gene of the histidine operon; it encodes the feedback-inhibitable first enzyme of the biosynthetic pathway. Previously, hisG mutants were mapped into seven intervals defined by the available deletion mutations having endpoints in the hisG gene. The map has been refined using over 60 new deletion mutants. The new map divides the gene into 41) deletion intervals, which average approximately 30 base pairs in length. The map has been used to analyze the distribution of insertion sites for the transposable element Tn10 and has permitted conclusions on the distribution of duplication endpoints. The map promises to be useful in analysis of his regulation and, more particularly, in the determination of the possible role of the hisG enzyme in this mechanism.
LYSOSOMAL DYSFUNCTIONS ASSOCIATED WITH MUTATIONS AT MOUSE PIGMENT GENES
Authors: Novak Edward K , Swank Richard T 
Published: April 2021

ABSTRACT
Melanosomes and lysosomes share several structural and biosynthetic properties. Therefore, a large number of mouse pigment mutants were tested to determine whether genes affecting melanosome structure or function might also affect the lysosome. Among 31 mouse pigment mutants, six had 1.5- to 2.5- fold increased concentrations of kidney β-glucuronidase. Three mutants, pale ear, pearl and pallid, had a generalized effect on lysosomal enzymes since there were coordinate increases in kidney β-galactosidase and a-mannosidase. The effects of these three mutations are lysosome specific since rates of kidney protein synthesis and activities of three nonlysosomal kidney enzymes were normal. Also, the mutants are relatively tissue specific in that all had normal liver lysomal enzyme concentrations.—A common dysfunction in all three mutants was a lowered rate of lysosomal enzyme secretion from kidney into urine. While normal C57BL/6J mice daily secreted 27 to 30% of total kidney β-glucuronidase and β-galactosidase, secretion of these two enzymes was coordinately depressed to l to e%, 8 to 9% and 4 to 5% of total kidney enzyme in the pale-ear, pearl and pallid mutants, respectively. Although depressed lysosomal enzyme secretion is the major pigment mutant alteration, the higher lysomal enzyme concentrations in pearl and pallid may be partly due to an increase in lysosomal enzyme synthesis. In these mutants kidney glucuronidase synthetic rate was increased 1.4 to 1.5-fold.—These results suggest that there are several critical genes in mammals that control the biogenesis, processing and/or function of related classes of subcellular organelles. The mechanism of action of these genes is amenable to further analysis since they have been incorporated into congenic inbred strains of mice.
THE DYNAMICS OF FINITE HAPLOID POPULATIONS WITH OVERLAPPING GENERATIONS. II. THE DIFFUSION APPROXIMATION
Authors: Emigh Ted H 
Published: April 2021

ABSTRACT
The dynamics of a gene in a haploid population can be explained approximately by considering the average reproductive value of the gene. The dynamics of the average reproductive value are similar to those of a gene in a population with nonoverlapping generations with the following modifications: The effective population size, Ne, replaces N; the average mutation rates,μ* and v* replace μ and v; the average overall selection r*+(T-l)s** replaces s; and time is measured in terms of generations, T. The implications of the average selection coefficient to adaptive life histones are discussed.
MUTAGENESIS BY CYTOSTATIC ALKYLATING AGENTS IN YEAST STRAINS OF DIFFERING REPAIR CAPACITIES
Authors: Ruhland Axel , Brendel Martin 
Published: April 2021

ABSTRACT
Reversion of two nuclear ochre nonsense alleles and cell inactivation induced by mono-, bi-, and tri-functional alkylating agents and by UV has been investigated in stationary-phase haploid cells of yeast strains with differing capacities for DNA repair. The ability to survive alkylation damage is correlated with UV repair capacity, a UV-resistant and UV-mutable strain (RAD REV) being least and a UV-sensitive and UV-nonmutable strain (rad1 rev3) most sensitive. Mutagenicity of alkylating agents is highest in the former and is abolished in the latter strain. Deficiency in excision repair (radl rad2) or in the RAD18 function does not lead to enhanced mutability. Mutagenesis by the various agents is characterized by a common pattern of induction of locus-specific revertants and suppressor mutants. Induction kinetics are mostly linear, but UV-induced reversion in the RAD REV strain follows higher-than-linear (probably "quadratic") kinetics. The alkylating agent cyclophosphamide, usually considered inactive without metabolic conversion, reduces colony-forming ability and induces revertants in a manner similar but not identical to the other chemicals tested. These findings are taken to support the concept of mutagenesis by misrepair after alkylation, which albeit sharing common features with the mechanism of UV-induced reversion, can be distinguished therefrom.
ULTRAVIOLET-INDUCED REVERSION OF cyc1 ALLELES IN RADIATION-SENSITIVE STRAINS OF YEAST. III. rev3 MUTANT STRAINS
Authors: Lawrence Christopher W , Christensen Roshan B 
Published: April 2021

ABSTRACT
The role of the REV3 gene function in UV-induced mutagensis in the yeast Saccharomyces cerevisiae has been examined by determining the reversion of 12 well-defined cycl mutations in diploid strains homozygous for the rev3—1 or rev3—3 allele. The 12 cycl alleles include one ochre, one amber, four initiation, two proline missense, and four frameshift mutations. We find that the rev3 mutations reduce the frequency of UV-induced reversion of all of the cycl alleles, though different classes of alleles respond to a different extent. These results imply that the REV3 gene function is required for the production of a wide variety of mutational events, though probably not all, and show that each of the three REV loci have different mutational phenotypes. Such diverse phenotypes are not predicted by the unitary model for bacterial mutagenesis (CAILLET-FAUQUET, DEFAIS and RADMAN 1977; WITKIN 1976), suggesting that this is at best an incomplete description of eukaryotic mutagenesis.
CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. II. THE X CHROMOSOME AND EGG VIABILITY
Authors: Chapco William 
Published: April 2021

ABSTRACT
Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg-to-adult viability. The results were compared with those of an earlier study involving egg production. All segments influence both traits, but to extents that are dependent upon the strains being compared. Segmental effects are also a function of the genetical background, which, in this case, constitutes material within the same chromowme. With respect to both traits, the segments are not necessarily parallel in their effects. A segment that increases fecundity, for example, may or may not augment viability. The possibility of manipulating chromosomal segments to improve "yield" in organisms is explored.
THE PROPHAGE OF SPβc2dcitK1, A DEFECTIVE SPECIALIZED TRANSDUCING PHAGE OF BACILLUS SUBTILIS
Authors: Rosenthal Richard , Toye Patryce A , Korman Ruth Z , Zahler Stanley A 
Published: April 2021

ABSTRACT
The defective specialized transducing phage SPβc2dcitK1 carries two known bacterial genes, kauA and citK, as well as SPβ phage markers including the heat-sensitive repressor allele, c2. Some phage genes (including essential ones) are missing. When SPβc2dcitK1 transduces SPβ-sensitive cells of Bacillus subtilis, the defective prophage is inserted into sites in the homologous bacterial DNA of the attSPβ-kauA-citK region of the recipient chromosome. During the growth of these transductants, occasional excisions occur that result in the loss of the phage genes and OI the heterogenotic state. These excisions increase greatly in frequency during growth at repressor-inactivating temperatures. The kinds of insertions and excisions seen suggest that a Campbell-type (CAMPBELL 1962) circular phage genome may occur transiently. If the transductants are superinfected by SPβc2 or by the clear-plaque mutant SPβc1, the resulting double lysogen can be heat induced to release high-frequency of-transduction (HFT) lysates for kauA and citK.
A MUTATOR AFFECTING THE REGION OF THE ISO-1-CYTOCHROME c GENE IN YEAST
Authors: Liebman Susan W , Singh Arjun , Sherman Fred 
Published: April 2021

ABSTRACT
The mutator gene DEL1 in the yeast Saccharomyces cerevisiae cauces a high rate of formation of multisite mutations that encompass the following three adjacent genes: CYC1, which determines the structure of iso-l-cyto-chrome c; RAD7, which controls UV sensitivity; and OSM1, which controls osomotic sensitivity. The simplest hypothesis is that these multisite mutations are deletions, although it has not been excluded that they may involve other types of gross chromosomal aberrations. In contrast, normal strains do not produce such multisite mutations even after mutagenic treatments.——The multisite mutations arise at a rate of approximately 10-5 to 10-6 per cell per division in DEL1 strains, which is much higher than rates observed for mutation of genes in normal strains. For example, normal strains produce all types of cycl mutants at a low rate of approximately 10-8 to 10-9. No evidence for multisite mutations was obtained upon analysis of numerous spontaneous adel, ade2, met2 and met15 mutants isolated in a DEL1 strain. DEL1 segregates as a single Mendelian gene closely linked to the CYC1 locus. DEL1 appears to be both cis- and trans-dominant. The location of the DEL1 gene and the lack of effect on other genes suggest that the mutator acts only on a region adjacent to itself.
GENETIC INSTABILITY IN DROSOPHILA MELANOGASTER: THE INDUCTION OF SPECIFIC CHROMOSOME 2 DELETIONS BY MR ELEMENTS
Authors: Green M M , Shepherd S H Y 
Published: April 2021

ABSTRACT
We describe the spontaneous induction of deletions by MR elements at the l(2)gl, net, pr and cn loci. The frequent induction of l(2)gl deletions mimics the high frequency of l(2)gl alleles found in wild populations of D. melanogaster. We suggest that these and other data that we present militate far the conclusion that, in the wild, autonomous MR elements occur and function as mutators. We contend that MR elements are not simply the by-products of hybridization between wild and laboratory strains.
SPONTANEOUS UNEQUAL EXCHANGE IN THE ROSY REGION OF DROSOPHILA MELANOGASTER
Authors: Gelbart William M , Chovnick Arthur 
Published: April 2021

ABSTRACT
A selective system for recovery of exchanges between trans mutations at adjacent loci, l(3)S12 and rosy, is described. In addition to the expected cross-over and conversion classes, two exceptional types of offspring were recovered. Triploid offspring arose as 0.01% of all zygotes; the diploid chromosome set was apparently of maternal origin. Nine tandem duplications derived from unequal exchange between nonsister homologues were recovered among 2.25 × 106 zygotes screened. From considerations of the proportion of the genome that was assayed in this system, and on the assumption that the rate of unequal exchange observed is typical for the genome as a whole, it appears that one unequal exchange occurs per 500 female meioses in Drosophila.
TWO NEW B-10 TRANSLOCATIONS INVOLVED IN THE CONTROL OF NONDISJUNCTION OF THE B CHROMOSOME IN MAIZE
Authors: Lin Bor-Yaw 
Published: April 2021

ABSTRACT
A B-A translocation, TB-1O(18), has been established involving breakpoints in the proximal region of the long arm of chromosome 1O and the minute short arm of the maize B chromosome. TB-l0(18) differs in its nondisjunctional behavior at the second microspore division froin TB-10(19), which has a breakpoint in the same region of IO but in the heterochromatic region of the long arm of B, in the following ways: (1) Nondisjunction of the B10 chromosome of the TB-l0(18) translocation occurs in the absence of the reciprocal element (10B), albeit at low frequency. (2) Presence of 1OB increases the frequency of B10 nondisjunction but not tc the level found for TB-l0(19) and certain other translocations. (3) The frequency of B10 nondisjunction varies among closely related sublines both when 1OB is present and when it is absent. It is inferred that the B10 of TB-lO(18) carries all the components of B necessary for nondisjunction but that expression is weak in the absence of 10B, suggesting the existence in the B chromosome short arm of a factor influencing efficient nondisjunction.
ENZYME POLYMORPHISM AND CYCLIC PARTHENOGENESIS IN DAPHNIA MAGNA. I. SELECTION AND CLONAL DIVERSITY
Authors: Young J P W 
Published: April 2021

ABSTRACT
Genotype frequencies and fecundities were recorded over a period of two years for three polymorphic enzyme loci (Est, Mdh and Got) in a parthenogenetic natural population of Daphnia magna Straus (Crustacea: Cladocera) . There was a large excess of heterozygotes at each locus, and some nonrandom association between loci, although 29 different three-locus genotypes were detected. There were small but significant changes in genotype frequencies that did not follow any clear seasonal cycles or overall trends, and the genotypes often differed significantly in fecundity, although the direction of the difference was not constant. These fitness differences were probably not attributable to the specific loci studied.—Models of balancing selection are of two types: segregation-balanced (e.g., heterosis) and competition-balanced (e.g., frequency dependence). Only the latter type can stabilize diversity in a clonal population. The observed selection was not heterotic, but it is not certain that it was stabilizing either. Clonal competition did not lead to victory by a single, fittest clone; genotypic diversity remained high.
SPECIFICITY OF INSERTION BY THE TRANSLOCATABLE TETRACYCLINE-RESISTANCE ELEMENT Tn10
Authors: Kleckner Nancy , Steele David A , Reichardt Katherine , Botstein David 
Published: April 2021

ABSTRACT
Genetic analysis of 131 independent transpositions of the tetracycline-resistance element TnlO from a single site in phage P22 into the histidine operon of Salmonella typhimurium reveals that Tn1O insertions are not randomly distributed along this chromosomal target. The insertions occur in 22 different "clusters"; insertions within each cluster are very tightly linked in recombination tests. TnlO insertions are not evenly distributed among the identified clusters. The existence of these clusters suggests that this chromosomal target contains particular genetic signals that guide TnlO to particular preferred positions for insertion. Insertions within each cluster occur in both orientations with roughly equal frequency.——The relationship among different insertions within each cluster has been examined. The resolution of genetic mapping places an upper limit of about 50 basepairs on the distance between different insertions within a cluster. Different insertions within a cluster usually have the same reversion frequency; however, heterogeneity in reversion frequency has been detected in at least two clusters. For most clusters, the available data are consistent with the simple possibility that all insertions within a cluster are at identical positions; however, the data do not exclude other possibilities.
MEIOTIC-LIKE RECOMBINATION IN VEGETATIVE DIKARYONS OF SCHIZOPHYLLUM COMMUNE
Authors: Frankel Carl 
Published: April 2021

ABSTRACT
A total of 65 Schizophyllum commune dikaryons of three different geno-types were synthesized, maintained on agar plates, prevented from fruiting, and macerated. The macerate was plated. Germlings of homokaryotic morphology were isolated using no chemical or genetic selection, grown, and tested for recombinant genotypes. Crossover types were plentiful among the homokaryons with recombinant genotypes, indicating that meiotic-like processes in vegetative dikaryons are common and may be as important as conventional basidial meiosis in the origin of recombinant strains.
HYBRID DYSGENESIS IN DROSOPHILA MELANOGASTER: STERILITY RESULTING FROM GONADAL DYSGENESIS IN THE P-M SYSTEM
Authors: Kidwell Margaret G , Novy Jill B 
Published: April 2021

ABSTRACT
Crosses between two types of strains, called P and M, characteristically give high frequencies of F1 sterility and other aberrant traits. Previous studies indicated that, in addition to the direction of the parental cross, many factors influence the manifestation of this phenomenon known as "hybrid dysgenesis."—The present study is concerned with the characteristics of GD (gonadal dysgenesis) sterility associated with the P-M system and its temperature dependence. Female sterility is accompanied by a complete absence of egg-laying, and this is not attributable to an inability to mate. Thus, it seems likely that sterility results from a defect in gametogenesis of hybrid individuals. This conclusion is supported by the morphological and cytological observations presented in an accompanying paper (SCHAEFER, KIDWELL and FAUSTO-STERLING 1979).—A narrow, critical, developmental temperature range was found in which both female and male sterility rose sharply from a low level to a high maximum. The critical range was 27 to 29° for males, slightly higher than the range of 24 to 26° for females. Two other dysgenic traits, male recombination and transmission ratio distortion, were affected by developmental temperature, but temperature response curves were quite different from those for sterility. The temperature-sensitiye stage for female sterility occurs during embryonic and early larval development.——GD sterility is compared and contrasted with SF sterility, another specific type of nonMendelian sterility resulting from a different interstrain dysgenic interaction.