bluuebunny/crossref_metadata_2025_split huggingface dataset:
ALLELIC COMPLEMENTATION IN THE FIRST GENE FOR HISTIDINE BIOSYNTHESIS IN SACCHAROMYCES CEREVISIAE. I. CHARACTERISTICS OF MUTANTS AND GENETIC MAPPING OF ALLELES
Authors: Korch Christopher T , Snow Richard 
Published: January 2021

ABSTRACT
A number of his1 mutants were tested for suppressibility, for reversion by EMS, ICR-170, and nitrous acid, for their allelic complementation response, and for their temperature sensitivity and osmotic remediability. None of 52 mutants tested was suppressible by a known ochre suppressor. This is a very surprising result compared with other studies of suppressibility in yeast and suggests that another function essential to the cell is associated with the his1 gene product, the polarity effect of a nonsense mutation destroying the activity of the his1 enzyme and this second function.
Sixty-four his1 alleles were ordered by allelic mapping methods utilizing gamma rays, X-rays, and MMS. The three maps agree well in placement of alleles and have been oriented on chromosome V of yeast with respect to the centromere. The 18 noncomplementing alleles are localized in the distal half of the gene, whereas the complementing alleles are distributed more or less evenly. Mutations which revert to feedback resistance map in the proximal end. Also at this end are mutations having a very high X-ray or MMS induced homoallelic reversion rate. This suggests that a number of missense mutations can occur in this region which result in innocuous amino acid substitutions in the enzyme. One X-ray map unit is estimated to correspond to about 131 base pairs or 43 amino acids, in agreement with results for the cytochrome-c protein obtained by Parker and Sherman (1969).
ALLELIC COMPLEMENTATION IN THE FIRST GENE FOR HISTIDINE BIOSYNTHESIS IN SACCHAROMYCES CEREVISIAE. II. COMPLEMENTATION MAPPING OF MUTANTS AND A SUBUNIT MODEL OF THE ENZYME
Authors: Korch Christopher T 
Published: January 2021

ABSTRACT
Sixty-two alleles of the histidine-1 (his1) gene were tested for complementation. The 44 complementing mutants fell into 31 complementation groups which were used to construct a complex complementation map with 18 complementation units. Cluster analysis of the complementation map by either visual inspection or the computer method of Gillie and Peto (1969) shows two very definite clusters. The molecular weight estimate of the his1 enzyme, phosphoribosyl adenosine triphosphate: pyrophosphate phosphoribosyltransferase, is 1.8 . 105 by sucrose density gradient analysis and 2.4 . 105 by Sephadex gel chromatography. Correlating the length of the his1 gene to the molecular weight of the enzyme indicates that this enzyme is composed of 6 subunits, as is the analogous enzyme in Salmonella typhimurium. A model of the subunit and tertiary and quaternary structure of the enzyme has been developed from consideration of the genetic and complementation data, the distribution of the various mutant types within the gene, and the biochemical properties of the enzyme encoded by the his1 gene.
DOSAGE COMPENSATION IN DROSOPHILA MELANOGASTER TRIPLOIDS. II. GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITY
Authors: Maroni Gustavo , Plaut Walter 
Published: January 2021

ABSTRACT
The level of activity of the enzyme glucose-6-phosphate dehydrogenase was determinel in flies having seven different chromosomic constitutions. All those having an integral number of chromosomes [XAA, XXAA, XAAA, XXAAA, and XXXAAA (X=X chromosome, A=set of autosomes)] were found to have similar units of enzyme activity/mg live weight, while diploid females with a duplication and triploid females with a deficiency showed dosage effect. The amount of enzyme activity per cell, on the other hand, is also independent of the number of X's present but appears roughly proportional to the number of sets of autosomes.—It is proposed that dosage-compensated sex-linked genes are controlled by a positively acting regulatory factor(s) of autosomal origin. With this hypothesis it is possible to explain dosage compensation as a consequence of general regulatory mechanisms without invoking a special device which applies only to the X chromosomes.
DIVERGENT SELECTION UNDER TWO NUTRITIONAL ENVIRONMENTS FOR PACKED ERYTHROCYTE VOLUME IN JAPANESE QUAIL
Authors: Stino F K R , Washburn K W 
Published: January 2021

ABSTRACT
Two-way selection for two-week packed erythrocyte volume (PCV) was practiced for four generations under two nutritional environments in the Japanese quail (Coturnix coturnix japonica). One environment was an iron, copper-"adequate" diet and the other was iron, copper-deficient "stress" diet. Response to selection was greater in both directions under the adequate environment than under the stress environment. After four generations of selection there were 29% and 18% differences between the high and low lines under the adequate and the stress environments, respectively. An asymmetry of response was observed toward the low line under the adequate environment and toward the high line under the stress environment. The realized heritability estimates for the high and low Fe-Cu-adequate lines were.26 and.35, respectively, while those for the high and low Fe-Cu-deficient lines were.16 and.06, respectively.
THYMINELESS MUTAGENESIS IN BACTERIOPHAGE T4
Authors: Smith M Diane , Green Ronald R , Ripley Lynn S , Drake John W 
Published: January 2021

ABSTRACT
Thymine deprivation can be achieved in bacteriophage T4 either by the use of the thymidylate synthetase inhibitor FUdR, or by an appropriate combination of genetic blocks; both methods produce marked mutagenesis. Extensive tests of the specificity of thymineless mutagenesis reveal that only A:T base pairs are affected, and that transitions and possibly transversions are produced. This system therefore constitutes the fist example of an A: T-specific mutagen. Thymineless mutagenesis in bacteriophage T4 exhibits a marked dependence upon the functional state of the DNA polymerase gene, but is largely independent of the px-γ misrepair system.
ON THE ORIGIN OF MITOCHONDRIAL MUTANTS: EVIDENCE FOR INTRACELLULAR SELECTION OF MITOCHONDRIA IN THE ORIGIN OF ANTIBIOTIC-RESISTANT CELLS IN YEAST
Authors: Birky C W 
Published: January 2021

ABSTRACT
In wild-type Sacchromyces cerevisiae, erythromycin and certain other antibacterial antibiotics inhibit the formation of respiratory enzymes in mitochondria by inhibiting translation on mitochondrial ribosomes. This paper is concerned with the origin of mutant cells, resistant to erythromycin by virtue of having a homogeneous population of mutant mitochondrial DNA molecules. Such mutant cells are obtained by plating wild-type (sensitive) cells on a nonfermentable substrate plus the antibiotic. Colonies of mutant cells appear first about four days after the time of appearance of established mutant cells; new colonies continue to appear, often at a constant rate, for many days. Application of the NEWCOMBrEes preading experiment demonstrates that most or all of the mutant cells which form the resistant colonies on selective medium arise only after exposure of the population to erythromycin. It is suggested that this result is most probably due to intracellular selection for mitochondrial genomes. Resistant mitochondria arising from spontaneous mutatLon are postulated to be at a selective disadvantage in the absence of erythromycin; reproducing more slowly than wild-type sensitive mitochondria, they cannot easily accumulate in sufficient numbers in a cell to render it resistant as a whole. In the presence of erythromycin, resistant mitochondria can continue to reproduce while sensitive mitochondria cannot, until there is a sufficient number to make the cell resistant, i.e. to permit normal cell growth. The same phenomenon is seen with respect to chloramphenicol resistance. Intracellular selection is considered more likely than direct induction of mutation by the antibiotic, since mutant cells do not accumulate in the presence of erythromycin if the mitochondrial genome is rendered nonessential by growth on glucose or nontranslatable by chloramphenicol. Intracellular selection provides a mechanism for direct adaptation at the cell level, compatible with currently acceptable ideas of spontaneous miitation and selection at the organelle level.
INDUCTION OF MITOTIC CROSSING OVER IN SACCHAROMYCES CEREVISIAE BY BREAKDOWN PRODUCTS OF DIMETHYLNITROSAMINE, DIETHYLNITROSAMINE, 1-NAPHTHYLAMINE AND 2-NAPHTHYLAMINE FORMED BY AN IN VITRO HYDROXYLATION SYSTEM
Authors: Mayer V W 
Published: January 2021

ABSTRACT
Dimethylnitrosamine and diethylnitrosamine, two potent carcinogens, are nonmutagenic when tested directly in microorganisms. Likewise 1-naphthylamine and 2-naphthylamine are also nonmutagenic but the N-hydroxy derivatives are mutagenic in microorganisms. Apparently these compounds require metabolism to breakdown products which are then the proximately active agents, and microorganisms lack the enzymes necessary to effect this conversion. These compounds are mutagenic in Saccharomyces after conversion to breakdown products in an in vitro hydroxylation medium. The induction of mitotic crossing over in Saccharomyces cerevisiae by breakdown products of dimethylnitrosamine, diethylnitrosamine, 1-naphthylamine and 2-naphthylamine formed in the Udenfriend hydroxylation medium is reported in this communication. Mitotic crossing over was detected as red sectored colonies resulting from induced homozygosity of the ade2 marker. Dimethylamine and diethylamine, which lack the nitroso group of the nitrosamines, did not induce mitotic crossing over under any of the test conditions. To further confirm that the induced sectored colonies were the result of mitotic crossing over they were tested for the presence of reciprocal products. The expected reciprocal products were found in over 67% of the isolates tested. The significance and practicality of using mitotic recombination as an indicator of genetic damage potential of chemicals is discussed.
GENETIC CONTROL OF INSECT POPULATIONS: I. CAGE STUDIES OF CHROMOSOME REPLACEMENT BY COMPOUND AUTOSOMES IN DROSOPHILA MELANOGASTER
Authors: Fitz-Earle M , Holm D G , Suzuki D T 
Published: January 2021

ABSTRACT
A genetic method for insect control was evaluated using the test organism, Drosophila melanogaster. The technique involved the displacement under a system of continuous reproduction, of standard strains by those carrying compound autosomes. The eradication of the replacements could subsequently be achieved through the use of temperature-sensitive lethal mutations.—While certain compound autosome strains failed to displace standards in population cages, even at the initial release ratio of 25:1, others were highly successful. Indeed, for some strains when the ratio of compounds to standards was as low as 9:1, the population rapidly went to fixation in favor of the compound line.—Hatchability was found to be an insufficient index of fitness to estimate the initial ratios of compounds to standards that would guarantee fixation of the former. Differences in other fitness components, such as development time, were detected that could seriously modify displacement, especially with continuous overlapping generations. The importance of examining the fitness of various compound lines and selecting the most competitive in cages, prior to field tests, cannot be overemphasized.
HYPERPRODUCTION OF DIHYDROFOLATE REDUCTASE IN DIPLOCOCCUS PNEUMONIAE AFTER MUTATION IN THE STRUCTURAL GENE. EVIDENCE FOR AN EFFECT AT THE LEVEL OF TRANSCRIPTION
Authors: Sirotnak F M , McCuen R W 
Published: January 2021

ABSTRACT
Dihydrofolate reductase is markedly hyperproduced in strains of Diplococcus pneumoniae which bear any one of a unique group of sense to sense mutations (amer) in the corresponding structural gene. Increased enzyme levels mediated by the amer mutations are apparently the result of increased rates of de novo synthesis. The basis for these effects could be transcriptional, translational or could involve an increase in messenger RNA stability. Data revealing no difference in stability of the related mRNA in a variety of mutants and the wild-type strain appear to eliminate the last possibility. Other data support the idea of an effect on transcription. This includes the extreme sensitivity of amer mutation expression following genetic transformation, to inhibition by actinomycin D and rifampacin, and the presence in one extremely high level mutant (amer-3 with 120 times the wild-type enzyme content) of increased amounts of mRNA. The data are most compatible with the idea of a regulatory function for the dihydrofolate reductase protein in this organism.
RECOGNITION OF STREPTOCOCCAL DNA BY A MUTANT PNEUMOCOCCUS UNABLE TO DISCRIMINATE AMONG MARKERS IN PNEUMOCOCCAL DNA
Authors: Tiraby Gerard , Ravin Arnold W 
Published: January 2021

ABSTRACT
A mutant strain of pneumococcus which fails to discriminate against low-efficiency markers during transformation by homospecific pneumococcal donor DNA retains the wild-type capacity to discriminate against heterospecific (streptococcal) donor DNA. We conclude that discrimination against heterospecific DNA must differ from that against low-efficiency markers by the kind or number of elements being recognized.
TWO DIFFERENT h
- MATING TYPES IN SCHIZOSACCHAROMYCES POMBE
Authors: Gutz Herbert , Doe Frank J 
Published: January 2021

ABSTRACT
In the strains of Schizosaccharomyces pombe introduced by Leupold (1950, 1958) into genetic research, heterothallic and homothallic mating types are known. The mating types are determined by two closely linked genes. We show that two distinct heterothallic - mating types exist: a stable one (h-S) and an unstable one (h-U), which can mutate to heterothallism + and homothallism. A proposal for incorporation of the new mating type h-U into Leupold's two-gene scheme is discussed.
COMPLEMENTATION ANALYSIS OF METABOLITE-RESISTANT MUTATIONS WITH FORCED HETEROKARYONS OF NEUROSPORA CRASSA
Authors: Thwaites W M , Knauert F K , Carney S S 
Published: January 2021

ABSTRACT
The double mutant strain pyr-3 arg-12s is a prototroph because a common precursor of arginine and pyrimidine is supplied by the arginine pathway. Growth of this strain is inhibited by exogenous citrulline or arginine. Citrulline-resistant mutants of this strain were selected, and they resulted from modifier mutations at other loci. Forced heterokaryons were used to study complementation among these modifiers. Since the complementation test requires the scoring of non-growth as the positive result, there was concern that variations in nuclear ratios could give erroneous results. This possibility does not seem significant, since groups of mutants established by complementation correspond with groups established by physiological, enzymatic, and recombinational measurements.—The technique has revealed that the most frequently mutated loci are arg-1 and what is probably un-3. Arg-1 mutations affect the conversion of citrulline to argininosuccinate, while un-3 mutations reduce the citrulline uptake rate. Since most of these mutations are of the intracistronic complementing type, a complementation map was constructed for most of the affected loci. The high proportion of complementors in each map can be explained by assuming that partially functioning gene products are more likely to complement with each other than are those which are nonfunctional.
COMPARISONS OF RELATIVE ACTIVITIES OF MAIZE Adh
1 ALLELES IN HETEROZYGOTES—ANALYSES AT THE PROTEIN (CRM) LEVEL
Authors: Schwartz Drew 
Published: January 2021

ABSTRACT
The method of high-resolution electrophoresis was employed to compare the relative amounts of enzyme produced by the Adh1F and Adh1S alleles in heterozygotes at different stages of development. The results are in complete agreement with those obtained from enzymatic analyses and support the competition hypothesis for the regulation of the alcohol dehydrogenase gene.
THE MECHANISM OF A BROODING EFFECT ASSOCIATED WITH SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER
Authors: Hartl D L 
Published: January 2021

ABSTRACT
The recovery of the SD chromosome from a heterozygous SD male increases with brood. This is independent of the age of the female, occurs during the time the sperm are stored in the females, disappears when the segregation distortion is suppressed, and is temperature-sensitive-temperature shocks above or below 25°C applied to the mature sperm both tend to accelerate the increase in the recovery of SD. All this suggests the existence of a class of sperm affected by SD in which the sperm are able to fertilize eggs for a short time following ejaculation but become dysfunctional thereafter.
GENE DUPLICATION WITHIN THE FAMILY SALMONIDAE: DISOMIC INHERITANCE OF TWO LOCI REPORTED TO BE TETRASOMIC IN RAINBOW TROUT
Authors: Allendorf Frederick W , Utter Fred M 
Published: January 2021

ABSTRACT
We describe our studies of the genetics of allelic variation for NADP-dependent isocitrate dehydrogenase (IDH) in rainbow trout (Salmo gairdneri). Five populations of rainbow trout were studied to determine the phenotypic distribution of IDH; 453 progeny from a number of controlled matings were examined to determine the nature of inheritance of these alleles. The variation was found to be the result of four alleles producing protein subunits of differing electrophoretic mobilities. Progeny from crosses clearly demonstrated the presence of two disomic loci controlling the variation, rather than one tetrasomic locus as had been previously reported. These findings support our contention that the hypothesis of a tetraploid event in salmonid evolution should not be uncritically accepted.
ANALYSES OF GENE FREQUENCIES OF MATES
Authors: Cockerham C Clark 
Published: January 2021

ABSTRACT
A genic analysis of variance of data on mate pairs for a codominant gene is developed. This analysis provides estimators of the correlation, F, of genes within individuals, of the correlation, Θ, of genes between mates, and of various variances-all relative to the correlation or variation among genes of nonmates. The data are manipulated into marginal distributions to produce another method of obtaining the same estimators. Several examples are given of how assumptions about the model and parameters modify the estimators and which were utilized in constructing X2 tests of hypotheses concerning F and Θ.—A recessive gene is also considered. Only the frequency of recessive genotypes and the correlation of recessive mates are estimable in this case unless one makes very demanding assumptions about the model.—Numerical examples of the analysis of variance and estimators are given for both a codominant and recessive gene.
RATES OF ELECTRON TRANSFER AND OF NON-CYCLIC PHOTOPHOSPHORYLATION FOR CHLOROPLASTS ISOLATED FROM MAIZE POPULATIONS SELECTED FOR DIFFERENCES IN JUVENILE PRODUCTIVITY AND IN LEAF WIDTHS
Authors: Hanson W D , Grier R E 
Published: January 2021

ABSTRACT
In vitro studies with chloroplasts isolated from maize populations differing in juvenile productivity by the sixth leaf stage of growth demonstrated differences in rates of ferricyanide reduction and of non-cyclic photophosphorylation. Similar results were obtained for two independent sets of replicate selections for high and for low productivity. Chloroplasts from low productive selections had about 115 percent of the reduction rate and 129 percent of the phosphorylation rate found for the high productive selections. Differences in ferricyanide reduction held for a fourfold range of experimentally induced rates. The contrasting rates of electron flow did not result from differential extraction environments following cell disruption nor from the failure to protect chloroplasts during extraction. Light-dependent phosphate uptake gave evidence, though inconclusive, of being so modified. No evidence was found for reciprocal effects between low-high and high-low hybrids. No difference in activities was found between chloroplasts isolated from two populations selected for narrow and for wide leaf widths. These two selections differed markedly in leaf areas. While in vitro measures of chloroplast efficiency reflected differences which were under genetic control, the results did not follow those expected from photosynthetic studies. The differences in rates appeared to reflect modification of processes other than those in the photosynthetic pathway.
SOMATIC CROSSING OVER IN GLYCINE MAX (L.) MERRILL: MUTAGENICITY OF SODIUM AZIDE AND LACK OF SYNERGISTIC EFFECT WITH CAFFEINE AND MITOMYCIN C
Authors: Vig B K 
Published: January 2021

ABSTRACT
Glycine max (soybean) is one angiosperm which lends itself to the study of somatic crossing over. This is made possible because some varieties have gene combinations Y11Y11, Y11y11 and y11y11 in the segregating populations from Y11y11 plants. The gene in question is responsible for chlorophyll synthesis. The Y11Y11 plants have dark green leaves, Y11y11 are light green and y11y11 plants are golden yellow. The heterozygous plants have dark green, yellow and dark green-yellow (double) spots on the leaves of the untreated control material, whereas the two homozygotes are almost always devoid of somatic sectoring. Application of caffeine, or mitomycin C, to the seeds increased the frequency of double, dark green and yellow spots on the Y11y11 background. Possibly, some dark green or yellow spots originate by failure of one of the two components of what might start as a double spot due to somatic crossing over. The application of NaN3 increases the frequency of dark green or yellow spots, almost exclusively. The two spots increase in equal frequency. The y11y11 plants so treated do not have any light green sectors, but dark green, Y11Y11, plants do develop a few light green or very dark green spots. The data indicate that NaN3 is capable of inducing nondisjunction, but does not cause mutations (at this locus), chromosome fragmentations (segmental losses) or somatic crossing over to an appreciable degree. It has previously been shown that caffeine-induced chromosome rejoining in Vicia faba can be inhibited by treating the roots with NaN3. In the present experiments NaN3 did not affect the processes of somatic crossing over as induced by caffeine or mitomycin C. The effect was additive. This system offers advantages for studying chemical mutagens in that somatic crossing over, point mutations, segmental losses through chromosome breakage and nondisjunction can all be studied in a single treatment to the seeds.
ISOLATION OF P22 SPECIALIZED TRANSDUCING PHAGE FOLLOWING F'-EPISOME FUSION
Authors: Kaye Robert , Barravecchio John , Roth John 
Published: January 2021

ABSTRACT
A P22 specialized transducing phage has been constructed which carries the structural gene for aspartate transcarbamylase (ATCase). This gene (pyrB) was first brought close to the P22 attachment site by fusing an F' pyrB + episome to an F' prolac episome which carries a P22 prophage attachment site. A prophage was added to these fused F' episomes and the lysogen was UV-induced. The specialized transducing phage was isolated from the resulting lysate. The phage also carries argI, the structure gene for ornithine transcarbamylase.
GENETIC CONTROL OF CHROMOSOMAL AND PLASMID RECOMBINATION IN STAPHYLOCOCCUS AUREUS
Authors: Wyman L , Goering R V , Novick R P 
Published: January 2021

ABSTRACT
Recombination-deficient mutants of Staphylococcus aureus have been isolated and found to have properties similar to those of recombination-deficient Escherichia coli. In addition, one Rec- mutant was found to be defective in the restriction and modification of DNA. There is a marked reduction (∼ 104-fold) in recombination between penicillinase plasmids in the Rec- mutants suggesting that these elements do not encode an efficient recombination system. There is, however, a demonstrable residuum of interplasmid recombination; evidence is lacking on whether this residuum is a plasmid or host function. In the absence of the generalized host recombination system it has been possible to demonstrate that interplasmid recombination occurs during vegetative bacteriophage growth and is presumably mediated by a phage-determined recombination system.