bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENETIC ANALYSIS OF PETITE MUTANTS OF SACCHAROMYCES CEREVISIAE: TRANSMISSIONAL TYPES
Authors: Perlman Philip S 
Published: April 2021

ABSTRACT
We have studied a number of petite [rho -] mutants of Saccharomyces cerevisiae induced in a wild-type strain of mitochondrial genotype [ome - CHLR ERYS OLIS 1,2,3 PARS] by Berenil and ethidium bromide, all of which have retained two mitochondrial genetic markers, [CHLR] and [ERYS], but have lost all other known markers. Though stable in their ability to retain these markers in their genome, these mutants vary widely among themselves in suppressiveness and in the extent to which the markers are transmitted on crossing to a common wild-type tested strain. In appropriate crosses all of the strains examined in this study demonstrate mitochondrial polarity, and thus have also retained the [ome -] locus in a functional form; however, five different transmissional types were obtained, several of them quite unusual, particularly among the strains originally induced by Berenil. One of the most interesting types is the one that appears to reverse the parental genotypes with [CHLR ERYS] predominating over [CHLS ERYR] in the diploid [rho+] progeny, rather than the reverse, which is characteristic of analogous crosses with [rho+] or other petites. Mutants in this class also exhibited low or no suppressiveness. Since all of the petites reported here are derived from the same wild-type parent, and so have the same nuclear background, we have interpreted the transmissional differences as being due to different intramolecular arrangements of largely common retained sequences.
SELECTION OF EXTRANUCLEAR MUTANTS OF NEUROSPORA CRASSA
Authors: Rosenberg Emiko , Mora Christina , Edwards David L 
Published: April 2021

ABSTRACT
A procedure is described that produces primarily extranuclear mutants of Neurospora crassa. An analysis of five mutants, [cni-3], [cni-4], [rsp-2], [rsp-3], [rsp-4] is presented. All five mutants segregate in an extranuclear manner. They can be assorted into two classes based on their respiratory properties: (1) those with cyanide-insensitive respiration (cni); (2) those with slow respiration (rsp). All of the mutants are female sterile. The respiratory trait can be placed in different nuclear backgrounds by heterokaryotic transfer. The abnormal respiratory traits are observed in mitochondria isolated from the mutants and it is likely that the mutations are in mitochondrial DNA.
FURTHER STUDIES ON THE RIBOSOMAL RNA CISTRONS OF SCIARA COPROPHILA (DIPTERA)
Authors: Gerbi Susan A , Crouse Helen V 
Published: April 2021

ABSTRACT
Additional experiments with homologous as well as heterologous hybridization confirmed our previous finding in Sciara coprophila that XX females have nearly twice the number of ribosomal RNA cistrons as X0 males. A comparison between two different X' chromosomes revealed that only the one carrying the irradiation-induced Wavy mutation has a deletion of 70% of its ribosomal RNA cistrons as compared to the standard X. The deletion is relatively stable, and the remaining ribosomal RNA cistrons do not appear to undergo disproportionate replication or magnification as in Drosophila. Homologous hybridization experiments revealed an unusually low reiteration of ribosomal RNA cistrons in this fly, 45 gene copies per X chromosome. The question is raised as to whether such a low number of cistrons may be related to the unusual nucleolar condition encountered in the Sciaridae.
THE CYTOGENETIC STUDY OF CROSSING OVER IN INTERSPECIFIC HYBRIDS BETWEEN DROSOPHILA VIRILIS AND D. TEXANA
Authors: Evgen'ev M B 
Published: April 2021

ABSTRACT
Spontaneous crossing over was studied by means of combined cytological and genetic methods in F1 Drosophila virilis x D. texanafemales (series I) and in D. virilis females carrying a D. texana fifth chromosome in heterozygous condition (series II). The main criterion utilized to distinguish the oogonial crossovers from the meiotic ones is the identity of cytological positions of genetic exchange in crossovers constituting a cluster. Five clusters of crossovers with identical positions of exchange were found in the first series of experiments. In the second series of experiments not a single cluster of crossovers resulting from oogonial crossing over was found.
MEIOSIS IN MALE DROSOPHILA MELANOGASTER. II. NONRANDOM SEGREGATION OF COMPOUND-SECOND CHROMOSOMES
Authors: Gethmann Richard C 
Published: April 2021

ABSTRACT
The segregation of compound-second chromosomes in males from two different stocks has been examined. Segregation is random in males from the C(2L)RM4, dp; C(2R)RM4, px stock. Gametes containing only one of the two compound chromosomes comprise 50% of the gametes, and gametes containing either both elements or neither element make up the other 50% of the gametes.——In males from the C(2L)RM, b; C(2R)RM, cn stock, gametes containing either C(2L)RM, b or C(2R)RM, cn make up the majority of the gametes. Gametes containing both chromosomes or neither chromosome account for only 2-3% of the gametes. The nonrandom segregation is due to the C(2R)RM, cn chromosome.——Viability is reduced in flies carrying the C(2R)RM, cn chromosome. This includes larval lethality, delayed development and premature adult lethality. Cytologically, this chromosome contains a large duplication of 2L material, which includes material proximal to region 38 or 39. It is suggested that the viability and segregational properties associated with this chromosome are due to the duplicated 2L material.
GENETIC ANALYSIS OF ASPARTATE AMINOTRANSFERASE ISOZYMES FROM HYBRIDS BETWEEN DROSOPHILA MELANOGASTER AND DROSOPHILA SIMULANS AND MUTAGEN-INDUCED ISOZYME VARIANTS
Authors: Grell E H 
Published: April 2021

ABSTRACT
The aspartate aminotransferases (designated GOT1 and GOT2) are two enzymes of Drosophila melanogaster for which naturally occurring electrophoretic variants were not found. There is an electrophoretic difference between D. melanogaster and D. simulans. Since the F1 hybrid offspring of these species are sterile, a genetic analysis of the ordinary type cannot be done on differences between the two species. A method was devised to make "partial hybrids" in which one chromosome arm is homozygous for melanogaster genes in an otherwise hybrid background. By using this method, Got1 was localized to 2R and Got2 to 2L. Once a gene can be assigned to a chromosome, it may be followed in crossing schemes and mutations from mutagen treatments may be looked for. At the locus of Got1 a mutation with low activity was recovered and designated Got1lo. It was located at a genetic map position of 75 on 2R. A Got2 mutant with a greater migration to the anode was recovered and designated Got2J. It was located at a genetic map position of 3.0, and in the salivary chromosome was between 22B1 and 22B4 inclusive.
DIPLOID GYNOGENESIS IN THE MEXICAN AXOLOTL
Authors: Trottier Thomas M , Armstrong John B 
Published: April 2021

ABSTRACT
Gynogenetic diploid axolotls were produced by activating eggs with ultraviolet-inactivated sperm, and then subjecting the activated eggs to heat shock. Optimal conditions for ultraviolet inactivation of the sperm, and for suppression of the second meiotic division by heat shock, were established. Gynogenetic diploids produced by these procedures included progeny homozygous for recessive alleles carried by a heterozygous mother. Gynogenesis could, therefore, be used to uncover new mutations more rapidly than by conventional inbreeding techniques. However, some difficulty was encountered in recognizing mutant phenotypes because of the high incidence of abnormalities and deaths. Defective embryos probably resulted from a combination of heat-shock-induced damage to the eggs and the expression of deleterious recessive alleles carried by the mother.
THE EVOLUTIONARY ADVANTAGE OF RECOMBINATION. II. INDIVIDUAL SELECTION FOR RECOMBINATION
Authors: Felsenstein Joseph , Yokoyama Shozo 
Published: April 2021

ABSTRACT
Based on the Fisher-Muller theory of the evolution of recombination, an argument can be constructed predicting that a recessive allele favoring recombination will be favored, if there are either favorable or deleterious mutants occurring at other loci. In this case there is no clear distinction between individual and group selection. Computer simulation of populations segregating for recessive or dominant recombination alleles showed selection favoring recombination, except in the case of a dominant recombination allele with deleterious background mutants. The relationship of this work to parallel investigations by Williams and by Strobeck, Maynard Smith, and Charlesworth is explored. All seem to rely on the same phenomenon. There seems no reason to assume that the evolution of recombination must have occurred by group selection.
THE GENETICS OF DOPA DECARBOXYLASE IN DROSOPHILA MELANOGASTER. II. ISOLATION AND CHARACTERIZATION OF DOPA-DECARBOXYLASE-DEFICIENT MUTANTS AND THEIR RELATIONSHIP TO THE α-METHYL-DOPA-HYPERSENSITIVE MUTANTS
Authors: Wright Theodore R F , Bewley Glenn C , Sherald Allen F 
Published: April 2021

ABSTRACT
Of 84 lethals isolated over the dopa decarboxylase (DDC) deficiency Df(2L)50, 8 have been identified as DDC-deficient alleles on the basis of their effect on DDC activity when heterozygous over the CyO balancer chromosome with activities ranging from 28% to 53% of controls. Some of the Ddc-deficient alleles exhibit intracistronic complementation. Most of the complementing pairs of alleles are much reduced in viability, e.g. &lt; 5% of expected, and express a common syndrome of mutant phenes which can reasonably be inferred to derive from inadequately sclerotinized cuticle. Individuals heterozygous for the noncomplementing allele, Ddcn7, over the 12-band DDC deficiency, Df(2L)130, die at the end of embryogenesis as unhatched larvae with unpigmented mouth parts.
The Ddc alleles and the l(2)amd α-methyl dopa (αMD) hypersensitive alleles are both located within the 11 band region 37B10-C7. The l(2)amd locus is immediately to the right of hk(2-53.9).Ddc has been mapped within 0.004 Map Units to the right of l(2)amd with a maximum estimated recombination frequency of 0.01%. None of the Ddc/CyO strains are sensitive to the dietary administration of α-methyl dopa (αMD), and complementation occurs between the Ddc deficient alleles and the l(2)amd alleles both on the basis of viability and DDC activity. No effect on DDC by the amd alleles has been found to date. Even in the complementing heterozygote, amdH1/amdH89, the level of activity, thermostability, and in vitro αMD inhibition of DDC remains unaffected. Although no biochemical phene has yet been established for the αMD hypersensitive amd alleles, it seems likely that the two groups of mutants are functionally related.
THE RIBOSOMES OF DROSOPHILA. III. RNA AND PROTEIN HOMOLOGY BETWEEN D. MELANOGASTER AND D. VIRILIS
Authors: Weber Lee , Berger Edward , Vaslet Charles , Yedvobnick Barry 
Published: April 2021

ABSTRACT
The extent of interspecific homology between D. melanogaster and D. virilis for ribosomal RNA and ribosomal protein was examined using the techniques of two-dimensional gel electrophoresis, and RNA-DNA filter hybridization. Only 2 of the 71 ribosomal proteins resolved were found to be species specific, while comparisons of soluble larval hemolymph protein patterns showed little similarity. Depending on the technique employed, the sequence homology for 18S + 28S ribosomal RNA was found to be between 83-94%, and sequence homology for 5S rRNA was judged to be complete.
SULFHYDRYL COMPOUNDS IN MELANOCYTES OF YELLOW (Ay/a), NONAGOUTI (a/a), AND AGOUTI (A/A) MICE
Authors: Galbraith Donald B , Patrignani Alan M 
Published: April 2021

ABSTRACT
Cleffmann (1953, 1963a,b) has reported that yellow but not black melanocytes of agouti (A/A) rabbits contained reducing sulfhydryl compounds. We have attempted to repeat Cleffmann's observations in mouse melanocytes of the lethal yellow (Ay/a), nonagouti (a/a) and agouti (A/A) genotypes. Our results contradict those of Cleffmann and reveal that yellow and black melanocytes, regardless of genotype, possess equivalent amounts of histochemically detectable sulfhydryl compounds. These results do not support the hypothesis that agouti-locus genes act by controlling the sulfhydryl metabolism of pigment cells.
TESTING FOR SELECTIVE NEUTRALITY OF ELECTROPHORETICALLY DETECTABLE PROTEIN POLYMORPHISMS
Authors: Weir B S , Brown A H D , Marshall D R 
Published: April 2021

ABSTRACT
The statistical assessment of gene-frequency data on protein polymorphisms in natural populations remains a contentious issue. Here we formulate a test of whether polymorphisms detected by electrophoresis are in accordance with the stepwise, or charge-state, model of mutation in finite populations in the absence of selection. First, estimates of the model parameters are derived by minimizing chi-square deviations of the observed frequencies of genotypes with alleles (0,1,2…) units apart from their theoretical expected values. Then the remaining deviation is tested under the null hypothesis of neutrality. The procedure was found to be conservative for false rejections in simulation data. We applied the test to Ayala and Tracey 's data on 27 allozymic loci in six populations of Drosophila willistoni. About one-quarter of polymorphic loci showed significant departure from the neutral theory predictions in virtually all populations. A further quarter showed significant departure in some populations. The remaining data showed an acceptable fit to the charge state model. A predominating mode of selection was selection against alleles associated with extreme electrophoretic mobilities. The advantageous properties and the difficulties of the procedure are discussed.
THE POPULATION GENETICS OF SPERM DISPLACEMENT
Authors: Prout Timothy , Bundgaard Jørgen 
Published: April 2021

ABSTRACT
This article reports the results of some sperm displacement experiments, as well as the results of a theoretical study of selection arising from genetic differences in displacing ability. The experimental work involved the use of three genetic marker stocks in double and triple matings. The speed of displacement following the matings was determined by scoring the progeny of each female daily. There were clear differences between strains in their displacing ability. It is shown how new information concerning the displacement process results when three markers are used; however, no new light is shed by these experiments on the mechanism of displacement.
The theoretical study of selection resulting from displacement uses a one-locus, two-allele model in which three diploid male genotypes confer different displacing abilities. The results indicate stable equilibria if (1) there is heterosis, and (2) there are certain nontransitive relationships in displacing ability among the different kinds of double matings.
Some evolutionary consequences are discussed in which sperm displacement is regarded as a form of sexual selection.
REGULATION OF NEWLY EVOLVED ENZYMES. III EVOLUTION OF THE ebg REPRESSOR DURING SELECTION FOR ENHANCED LACTASE ACTIVITY
Authors: Hall Barry G , Clarke Norma D 
Published: April 2021

ABSTRACT
The evolution of lactose utilization by lacZ deletion strains of E. coli occurs via mutations in the ebg genes. We show that one kind of mutation in the regulatory gene ebgR results in a repressor which retains the ability to repress synthesis of ebg enzymes, but which permits 4.5-fold more ebg enzyme synthesis during lactose induction than does the wild-type repressor. A comparison between the growth rate of various ebg + strains on lactose and the amount of ebg enzyme synthesized by these strains shows that the rate of enzyme synthesis permitted by the wild-type repressor is insufficient for growth on lactose as a sole carbon source by a cell with the most active ebg lactase yet isolated. We conclude, therefore, that the evolution of lactose utilization requires both a structural and a regulatory mutation.
BIPARTITE STRUCTURE OF THE ade3 LOCUS OF SACCHAROMYCES CEREVISIAE
Authors: Jones Elizabeth W 
Published: April 2021

ABSTRACT
Forty ade3 mutants were examined with respect to their growth requirements, levels of the tetrahydrofolate interconversion enzymes, and/or map positions. Four deletions were detected. Mutations that result in a requirement for adenine and histidine map in one region of the locus; those which result in a requirement for adenine only map in a quite separate region of the locus, a region not disclosed in previous studies. No correlation was observed between growth properties of the strains and enzyme levels.
KINETICS OF MUTATION INDUCTION BY ULTRAVIOLET LIGHT IN EXCISION-DEFICIENT YEAST
Authors: Eckardt Friederike , Haynes R H 
Published: April 2021

ABSTRACT
We have measured the frequency of UV-induced reversions (locus plus suppressor) for the ochre alleles ade2-1 and lys2-1and forward mutations (ade2 adex double auxotrophs) in an excision-deficient strain of Saccharomyces cerevisiae (rad2-20). For very low UV doses, both mutational systems exhibit linear induction kinetics. However, as the dose increases, a strikingly different response is observed: in the selective reversion system a transition to higher order induction kinetics occurs near 9 ergs/mm2 (25% survival), whereas in the nonselective forward system the mutation frequency passes through a maximum near 14 ergs/mm2 (4.4% survival) and then declines. This contrast in kinetics cannot be explained in any straightforward way by current models of induced mutagenesis, which have been developed primarily on the basis of bacterial data. The bacterial models are designed to accommodate the quadratic induction kinetics that are frequently observed in these systems. We have derived a mathematical expression for mutation frequency that enables us to fit both the forward and reversion data on the assumptions that mutagenesis is basically a "single event" Poisson process, and that mutation and killing are not necessarily independent of one another. In particular, the dose-response relations are consistent with the idea that the sensitivity of the revertants is about 25% less than that of the original cell population, whereas the sensitivity of the forward mutants is about 29% greater than the population average. We argue that this relatively small differential sensitivity of mutant and nonmutant cells is associated with events that take place during mutation expression and clonal growth.
THE EVOLUTION OF ONE- AND TWO-LOCUS SYSTEMS. II
Authors: Nagylaki Thomas 
Published: April 2021

ABSTRACT
Weak selection in a monoecious population is studied in two multiallelic panmictic models. In the first, a single locus is considered with continuous time and age-independent fertilities and mortalities. If the fertilities of the various matings and the genotypic mortalities may be expressed with an error at most of the second order in s (i.e., O(s 2)), where s is the intensity of selection, as sums of terms corresponding to the different genotypes and alleles, respectively, then after several generations the deviations from Hardy-Weinberg proportions are of O(s 2). In the second model, two loci are treated with discrete nonoverlapping generations. It is shown that if the epistatic parameters are of O(s2), then after several generations the linkage disequilibria are reduced to O(s 2). Assuming only weak selection, it is proved that in both models, after several generations, the total change in mean fitness is generally positive. It is likely that the exclusion of the initial period is usually unnecessary in natural populations. Exceptions are discussed.
A METHOD FOR FATE MAPPING THE FOCI OF LETHAL AND BEHAVIORAL MUTANTS IN DROSOPHILA MELANOGASTER
Authors: Flanagan James R 
Published: April 2021

ABSTRACT
A new method of mosaic fate mapping, called focusing, is introduced. Its advantages are that it allows a mapping, on the blastoderm surface, of the site of action of functions defined by either pre-adult lethal or behavioral mutations. Moreover, it does not require that the mosaics used be 50% of one genotype and 50% of the other. Methods for quantitative evaluation of the results of focusing, and a comparison of this method with others, are discussed.—Focusing is applied to the analysis of a new mutant, doomed (symbol: dmd), a distally located X-linked recessive in D. melanogaster, that causes the deaths of males and females around the time of eclosion. The dmd phenotype among eclosing flies is first seen as the loss of thoracic motor coordination and as ether sensitivity. Fate mapping by the method of focusing places the site of action of the dmd + function in the same region of the map as that of the thoracic neural ganglia primordia, but not that of muscle, suggesting the possibility that the effect of dmd is on a thoracic neural function rather than a muscular one.
TRAUMATIC INDUCTION OF EARLY MATURITY IN TETRAHYMENA
Authors: Nanney D L , Meyer E B 
Published: April 2021

ABSTRACT
Exposure of conjugating pairs of Tetrahymena thermophila to high temperature (37°) during macronuclear development causes an abortion of many macronuclei, but it also often induces an early appearance of sexual maturity in clones completing macronuclear development. Lines become mature after about 15 cell divisions rather than after 50 or more cell divisions in untreated pairs. The phenotype resembles that associated with Em (early maturity) mutants but, because it is not transmitted to the progeny in the next generation, it must be considered a phenocopy. The hypothesis is developed that an early genotype-environment incompatibility, whether associated with an abnormal genotype or an unusual environment, activates a shunt mechanism permitting the organisms to undertake quickly an ordinarily forbidden sexual lottery.
SITES OF THE 5S RIBOSOMAL GENES IN DROSOPHILA. I. THE MULTIPLE CLUSTERS IN THE VIRILIS GROUP
Authors: Wimber D E , Wimber Doris R 
Published: April 2021

ABSTRACT
Drosophila melanogaster 125I-5S RNA was annealed to salivary gland preparations of 6 species in the virilis group of Drosophila. Two patterns of annealing were found. D. virilis, D. montanaand D. borealis showed three 5S gene clusters on chromosome 5; Sd-f and Wc-j were strongly labeled, but Xa-e was weakly labeled. D. montana and D. borealis have a greater percentage of their total 5S cistrons at S d-f than does D. virilis. D. americana americana, D. americana texana and D. novamexicana showed 2 sites labeled; no label was seen at Sd-f while Wc-j was weakly labeled and Xa-e was strongly labeled, the reciprocal of the previous pattern in the W-X region. Hybrids between D. a. americana and D. virilis showed no difference in chromosome banding at the sites of the 5S clusters despite their pattern differences. D. a texana x D. virilis, on the other hand, did show a difference in staining the Xa-e region. These patterns fall squarely into the biosystematic groupings deduced by many previous workers.