bluuebunny/crossref_metadata_2025_split huggingface dataset:
CYTOLOGICAL IDENTIFICATION OF THE CHROMOSOMES INVOLVED IN SEARLE'S TRANSLOCATION AND THE LOCATION OF THE CENTROMERE IN THE X CHROMOSOME OF THE MOUSE
Authors: Eicher Eva M , Nesbitt Muriel N , Francke Uta 
Published: January 2021

ABSTRACT
The autosome in Searle's X-autosome translocation has been shown to be chromosome 16. The breakpoint in chromosome 16 is slightly proximal to the middle and in the X is slightly distal to the middle.—Available evidence indicates that either Linkage Group XV or Linkage Group XIX is carried on chromosome 16.—The centromere of the X chromosome is at the spf end of the linkage group.
SOMATIC SEGREGATION, RECOMBINATION, ASYMMETRICAL DISTRIBUTION AND COMPLEMENTATION TESTS OF CYTOPLASMICALLY-INHERITED ANTIBIOTIC-RESISTANCE MITOCHONDRIAL MARKERS IN S. CEREVISIAE
Authors: Rank G H , Bech-Hansen N T 
Published: January 2021

ABSTRACT
Genetic analyses of 48-hr-old zygote-daughter-colony cells from crosses between chloramphenicol and erythromycin resistance markers located in mitochondrial DNA demonstrated homoplasmons of parental and recombinant genotypes, and heteroplasmons with recombinant and/or parental genotypes. Although the heteroplasmons were unstable and the homoplasmic components could be segregated by plating on selective media, the heteroplasmic state was often maintained beyond 19 cell divisions when grown on non-selective medium. Homoplasmons of recombinant genotype from repulsion crosses were observed with a frequency of 7.2, 9.0, 11.2 and 11.4 percent; two crosses with the resistance markers in coupling had 5.4 and 11.5 percent recombinants. Under non-selective conditions, the mitochondrial marker derived from the haploid parent of a mating type predominated in zygote-daughter-cells; this asymmetrical distribution could be reversed by selective pressure for the marker transmitted with low frequency. The challenge with chloramphenicol and erythromycin of zygotes from crosses of resistance-markers in repulsion revealed that inter-mitochondrial complementation was not occurring.
LONG-TERM SELECTION RESPONSE FOR 12-DAY LITTER WEIGHT IN MICE
Authors: Eisen E J 
Published: January 2021

ABSTRACT
Long-term selection for increased 12-day litter weight in two replicate lines (W2, W3) of mice resulted in an apparent selection limit at about 17 generations. Quadratic polynomial and exponential models were fitted to the data in order to estimate the plateaued response and half-life of the selection process. Using the polynomial results, the half-life estimates were 4.5 and 8.6 generations for W2 and W3, respectively. The plateaued responses were 5.1 and 5.8 g which, when expressed in phenotypic standard deviation units, became 1.1 and 1.3. The exponential model provides similar estimates. A negative association between 12-day litter weight and fitness was not considered to be an adequate explanation for the plateau since there was no decrease in fertility of the selected lines. Evidence that exhaustion of genetic variability was not the cause of the plateau came from the immediate response to reverse selection. It was proposed that the plateau may be due to a negative genetic correlation between direct and maternal genetic effects, which would be expected to occur after many generations of selection. There were positive correlated responses in both replicates for adult body weight, which was in agreement with the positive genetic correlation between preweaning and postweaning body weight. The expected positive correlated response for number born was realized in only one of the replicates.
CLONAL VARIATION IN PARAMECIUM. I. PERSISTENT UNSTABLE CLONES
Authors: Finger Irving , Heller Carol , Dilworth Linda , Allmen Carolyn Von 
Published: January 2021

ABSTRACT
Clones of Paramecium of identical serotype when cultured in test tubes may differ in their ability to give rise to subclones of this serotype. Characteristically, stable clones yield progeny indistinguishable from their parents, while from unstable clones diverse subclones with new serotypes can be isolated repeatedly. Stable lines are resistant to changes in culture medium and also are unaffected by most sera. In contrast, the numbers and kinds of serotypes displayed among subclones derived from unstable lines are often affected by these same agents. Stable and unstable clones are interconvertible when the medium from individual cultures is repeatedly and frequently replaced by fresh culture fluid. This effect is very likely a result of the removal of the initial exhausted medium with any cell products rather than the addition of fresh nutrient.
GENETIC ANALYSIS OF MUTATIONS INDIRECTLY SUPPRESSING recB AND recC MUTATIONS
Authors: Templin Ann , Kushner Sidney R , Clark Alvin J 
Published: January 2021

ABSTRACT
Mutations in sbcB inactivate exonuclease I and suppress the UV-sensitive, mitomycin-sensitive, recombination-deficient phenotypes associated with recB and recC mutations. Mapping experiments have located sbcB about 0.4 minutes from the his operon at 38.0 on the standard map of E. coli. This places sbcB between supD and his. A four-point cross shows that sbcB lies between P2 attH and his. P2 eduction deleting the his operon beginning with P2 attH also deletes sbcB and produces the expected exonuclease I deficiency and suppression of recB -. The occurrence of chemical-mutagen-induced and spontaneous mutations indirectly suppressing recB - and recC - is examined. Three lines of strains produce only sbcA mutations while only sbcB mutations occur in a fourth line. Explanations for this behavior are proposed in light of the ability of the first three lines to express sbcB mutations which they inherit by transduction.
NUCLEIC ACID HYBRIDIZATION STUDIES WITHIN THE GENUS CUCURBITA
Authors: Goldberg Robert B , Bemis William P , Siegel Albert 
Published: January 2021

ABSTRACT
The DNAs of Cucurbita species were examined by several methods. All Cucurbita DNAs have a similar CsCl isopycnic banding pattern consisting of a major band at 1.695 g/cc and a well separated satellite band at 1.707 g/cc. Compared to other plant and animal genera, Cucurbita species have a large genomic proportion of rDNA; this value ranging from 1.4% to 3.1%. The genomic proportion of rDNA was found not to be useful as a characteristic indicating degree of relatedness of the various Cucurbita species. However, Cucurbita DNAs can be distinguished by the extent to which their repetitive sequences cross-hybridize to each other and an assessment of species relationships can be made on this basis.
THE RELATIVE INFLUENCE OF SEX OF PROGENY ON THE LETHAL EXPRESSION OF THE SONLESS GENE IN DROSOPHILA MELANOGASTER
Authors: Colaianne James J , Bell A E 
Published: January 2021

ABSTRACT
The sex-linked maternally influenced lethal gene, sonless (snl), in D. melanogaster was shown to affect the survival of daughters as well as sons of snl/snl mothers but to a lesser degree. Interaction studies of sonless with the sex altering mutants transformer (tra) and doublesex (dsx) revealed that any alteration toward increased masculinity of progeny from snl/snl females reduced their zygotic viability, independent of snl dosage or Y chromosome presence or absence. Possible implications of these results are discussed and the original gene action hypothesis for snl is extended to incorporate these new findings.—Sonless is non-allelic but closely linked to rudimentary (r) and fused (fu), two mutants with similar sex-ratio patterns.
ENZYME EVOLUTION: I. THE IMPORTANCE OF UNTRANSLATABLE INTERMEDIATES
Authors: Koch Arthur L 
Published: January 2021

ABSTRACT
The proportion of two allelic mutant forms of a haploid species can be calculated from six quantities, the original proportion, the two effective growth rate constants, the two mutation rate constants for the transition from one to the other, and the elapsed time. With a program for carrying out this calculation in a mini-computer, we set about investigating the rates of exploration of multiple intragene changes in populations of enormous numbers over a large number of cell generations. It seemed evident from the outset that unless in the past very different proportions of the different types of mutational changes occurred, then neither the numbers nor the times could have been of sufficient magnitude to account for enzyme evolution by multiple simultaneous changes within a gene to yield a superior protein. Rather, we propose that the more rapid path of enzyme evolution consisted of the sequence: 1) gene duplication, 2) inactivation of a gene copy by a chain-terminating mutation or other mutational change which suppresses transcription and/or translation, 3) multiple base-pair changes and/or small deletions and additions within the non-functioning gene, and finally, 4) reversion of the mutation which was suppressing translation. It is shown that this path will lead to faster advance, if the selective advantages of different forms are dependent on the function of the gene products at certain times in history, while at other times, although this function may be necessary, it is not limiting for growth.
MUTATION RATE AND DOMINANCE OF GENES AFFECTING VIABILITY IN DROSOPHILA MELANOGASTER
Authors: Mukai Terumi , Chigusa Sadao I , Mettler L E , Crow James F 
Published: January 2021

ABSTRACT
Spontaneous mutations were allowed to accumulate in a second chromosome that was transmitted only through heterozygous males for 40 generations. At 10-generation intervals the chromosomes were assayed for homozygous effects of the accumulated mutants. From the regression of homozygous viability on the number of generations of mutant accumulation and from the increase in genetic variance between replicate chromosomes it is possible to estimate the mutation rate and average effect of the individual mutants. Lethal mutations arose at a rate of 0.0060 per chromosome per generation. The mutants having small effects on viability are estimated to arise with a frequency at least 10 times as high as lethals, more likely 20 times as high, and possibly many more times as high if there is a large class of very nearly neutral mutations.—The dominance of such mutants was measured for chromosomes extracted from a natural population. This was determined from the regression of heterozygous viability on that of the sum of the two constituent homozygotes. The average dominance for minor viability genes in an equilibrium population was estimated to be 0.21. This is lower than the value for new mutants, as expected since those with the greatest heterozygous effect are most quickly eliminated from the population. That these mutants have a disproportionately large heterozygous effect on total fitness (as well as on the viability component thereof) is shown by the low ratio of the genetic load in equilibrium homozygotes to that of new mutant homozygotes.
DIRECT INDUCTION IN WILD-TYPE NEUROSPORA CRASSA OF MUTANTS (qa-1C) CONSTITUTIVE FOR THE CATABOLISM OF QUINATE AND SHIKIMATE
Authors: Partridge C W H , Case Mary E , Giles Norman H 
Published: January 2021

ABSTRACT
A color test has been developed for the selection and identification of mutants in Neurospora crassa, constitutive for the three normally inducible enzymes which convert quinate to protocatechuate. By this means seven such mutants have been recovered after ultra violet irradiation of wild type and have been shown to be allelic (or very closely linked) to the qa-1C mutants previously obtained by other means. Thus, the regulation of the synthesis of these three catabolic enzymes is indicated to be under the control of a single gene, qa-1+.
CHARACTERIZATION OF THE DNA IN DROSOPHILA MELANOGASTER
Authors: Travaglini E C , Petrovic J , Schultz J 
Published: January 2021

ABSTRACT
DNA has been quantitatively extracted from Drosophila melanogaster at various stages of embryonic development and analyzed by isopycnic centrifugation in CsCl and by fractionation on methylated albumin columns. The DNA is composed of three main classes of DNA, as defined by their buoyant density, ρ, in CsCl: a bulk DNA, ρ = 1.699 g cm-3, and two satellite DNAs, ρ = 1.685 g cm-3 and ρ = 1.669 g cm-3. These three types of DNA persist throughout the development of the insect. In the unfertilized egg, 80% of the total DNA consists of the satellite DNAs; this amount decreases to 18% during the first three hours after fertilization and then remains constant through embryogenesis. There is a concomitant increase of the satellite DNA's with the bulk DNA after blastoderm formation.
THE EFFECT OF RADIATION-INDUCED MUTATIONS ON THE FITNESS OF DROSOPHILA POPULATIONS
Authors: Blaylock B G , Shugart H H 
Published: January 2021

ABSTRACT
The change in frequencies of D. melanogaster and D. simulans in competition experiments was used to measure the effect of radiation on the fitness of a population. A dose of 250 or 500 rads given to the males of highly inbred lines of D. simulans at the beginning of competition and every three weeks thereafter increased the relative frequency of the irradiated population. If the dose was increased to 1000 rads, the deleterious effects of radiation became too great a burden on the population, and the frequency of the irradiated population decreased. From these results it was concluded that below certain doses the introduction of radiation-induced mutations into a highly homozygous population would increase the fitness of the population.
THE EFFECT OF SELECTION ON ESTERASE ALLOZYMES IN A BARLEY POPULATION
Authors: Allard R W , Kahler A L , Weir B S 
Published: January 2021

ABSTRACT
Changes in gene and genotypic frequencies at four esterase loci were monitored over 25 generations in Composite Cross V, an experimental population of barley, to obtain experimental evidence concerning the balance of forces responsible for: (1) the marked differences in allelic frequencies among barleys from different ecogeographical regions of the world; and (2) the extensive allelic variation found within local populations of barley. Analyses of the highly significant changes in allelic frequencies which occurred in CCV showed they were due to directional selection favoring particular alleles and not to mutation, migration or genetic drift. The results show that intense balancing selection, featuring consistent excesses of heterozygotes, also occurred in CCV. It is concluded that among the factors of neo-Darwinian evolution, natural selection plays the predominant role in determining the observed patterns of allelic variation in the barley species as a whole.
STUDIES ON THE SAL LOCUS IN DROSOPHILA PSEUDOOBSCURA. II. MODES OF REGULATION OF THE SAL BANDING PATTERN
Authors: Gersh Eileen Sutton 
Published: January 2021

ABSTRACT
From a consideration of genetic and chromosomal alterations which affect the banding pattern of a specific salivary chromosome region, it is concluded that (1) a regulator locus, sal, is closely linked with the region in question but separated from it spatially by a few bands; (2) either mutation of the sal locus or transfer of the region to a heterochromatic region affects the banding pattern similarly; and (3) the change probably consists of a compaction of DNA and a concomitant inactivation of genetic loci.
CHEMICAL SELECTION OF ALCOHOL DEHYDROGENASE NEGATIVE MUTANTS IN DROSOPHILA
Authors: Sofer William H , Hatkoff Mark A 
Published: January 2021

ABSTRACT
We describe a selection procedure which utilizes the vapor from an unsaturated alcohol, 1-pentene-3-ol, for the detection and isolation of mutant flies with little or no alcohol dehydrogenase activity. ADH-negative flies are unaffected by exposure to the unsaturated alcohol, but ADH positives (wild-types) die after short exposure. The technique can be used to select rare ADH-negative individuals from large populations of wild-type flies.
CONGRESSION OF UNLINKED MARKERS AND GENETIC MAPPING IN THE TRANSFORMATION OF BACILLUS SUBTILIS 168
Authors: Erickson Robert J , Copeland James C 
Published: January 2021

ABSTRACT
A thorough examination of cotransformation of two unlinked genetic markers in Bacillus subtilis 168 shows that the two recombinational events do not occur randomly. The cotransformation frequency is dependent on the distance between the two markers as well as on the order in which they replicate in the competent cell. These results indicate that uptake and/or integration of DNA molecules bearing these genetic markers is enhanced at the time these markers replicate in the competent cell.
RECOMBINATION AND DNA REPLICATION IN THE DROSOPHILA MELANOGASTER OOCYTE
Authors: Grell Rhoda F 
Published: January 2021

ABSTRACT
A method is described that permits the recovery of a well-synchronized population of oocytes. Utilizing this pupal system, the heat-responsive period for increasing crossing-over in the Drosophila genome has been defined for the Χ chromosome and a portion of chromosome 2. The response is initiated close to the time of oocyte formation (premeiotic interphase) and is terminated after ~36 hr. During the 36-hr period different regions show characteristic responses, which vary in degree, in duration, and in initiation and termination points, so as to generate the beginning of a thermal recombination map for the Drosophila genome. Centromere regions exhibit the greatest increases in crossing-over for their respective chromosomes but are distinctly asynchronous in time; interstitial regions respond the least. Correlated autoradiographic studies have localized DNA replication in the oocyte to a ~24-hr period, which also begins close to oocyte formation (premeiotic interphase); late labeling in restricted regions, undetectable with the present method, could extend the period, as could prolonged synthesis in the oocyte. The results demonstrate that DNA replication and the heat-sensitive period for enhancement of crossing-over are coincident processes over most and possibly all of their length.
THE GENETIC SYSTEM CONTROLLING HOMOTHALLISM IN SACCHAROMYCES YEASTS
Authors: Harashima Satoshi , Nogi Yasuhisa , Oshima Yasuji 
Published: January 2021

ABSTRACT
There are four types of life cycles in Saccharomyces cerevisiae and its related species. A perfect homothallic life cycle (the Ho type) is observed in the classic D strain. Two other types show semi-homothallism; one of them shows a 2-homothallic diploid:2α heterothallic haploid segregation (the Hp type) and another, a 2-homothallic:2a segregation (the Hq type). In the segregants from these Ho, Hp, and Hq diploids, each homothallic segregant shows the same segregation pattern as its parental diploid. The fourth type has a heterothallic life cycle showing a 2a:2α segregation and the diploids are produced by the fusion of two haploid cells of opposite mating types. The diploids prepared by the crosses of α Hp (an α haploid segregant from the Hp diploid) to a Hq (an a haploid from the Hq diploid) segregated two types (Type I and II) of the Ho type homothallic clone among their meiotic segregants. Genetic analyses were performed to investigate this phenomenon and the genotypes of the Ho type homothallic clones of Type I and Type II. Results of these genetic analyses have been most adequately explained by postulating three kinds of homothallic genes, each consisting of a single pair of alleles, HO/ho, HMα/hmα, and HMa/hma, respectively. One of them, the HMα locus, was proved to be loosely linked (64 stranes) to the mating-type locus. A spore having the HO hmα hma genotype gives rise to an Ho type homothallic diploid (Type I), the same as in the case of the D strain which has the HO HMα HMa genotype (Type II). A spore having the a HO hmα HMa or α HO HMα hma genotype will produce an Hp or Hq type homothallic diploid culture, respectively. The other genotypes, a HO HMα hma, α HO hmα HMa, and the genotypes combined with the ho allele give a heterothallic character to the spore culture. A possible molecular hypothesis for the mating-type differentiation with the controlling elements produced by the HMα and HMa genes is proposed.
REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA: ISOLATION OF MUTANTS DEFICIENT IN THE REPRESSIBLE ALKALINE PHOSPHATASE
Authors: Gleason Mary K , Metzenberg Robert L 
Published: January 2021

ABSTRACT
Mutants of Neurospora crassa have been isolated that lack the repressible alkaline phosphatase, but, unlike nuc-1 and nuc-2 mutants, are able to make the repressible acid phosphatase and the repressible phosphate permease under conditions of derepression (phosphate deprivation). The new mutants, called pho-2, map in Linkage Group V, and are unlinked to the putative control mutants, nuc-1, nuc-2-pconc, and pregc. Three of the pho-2 mutants do not make detectable amounts of repressible alkaline phosphatase, but the fourth makes about 1% of the level found in wild type. The small amount of alkaline phosphatase made by this strain appears to be qualitatively similar or identical to the wild-type enzyme, as judged by electrophoretic mobility, heat stability, and titration with specific antibody to the wild-type enzyme. Several revertants of this strain have been examined in the same way, and the alkaline phosphatase of these strains also appears to be qualitatively normal. Reversion events can occur at, or near, the pho-2 locus, but also occur in at least two unlinked sites (suppressor mutations). One suppressor maps very close to nuc-1.
RECONSTITUTION OF THE Rr COMPOUND ALLELE IN MAIZE
Authors: Dooner H K , Kermicle J L 
Published: January 2021

ABSTRACT
The Rr:standard allele in maize, which conditions anthocyanin pigmentation in plant and seed tissues in the presence of appropriate complementary factors, is associated with a tandem duplication. The proximal member of the duplication carries P, the plant pigmenting determiner and the distal member member carries S, the seed pigmenting determiner. Derivatives from Rr that have lost S function are designated rr. They represent either losses of the distal member of the duplication (P derivatives) or mutations of S to s (P s). Derivatives that have lost P function are designated Rg, and represent either losses of the proximal member of the duplication (S derivatives) or mutations of P to p (p S).—All four possible types of rr/Rg heterozygotes were tested for their capacity to yield Rr reconstitution by crossing over. No Rr derivatives were obtained from P/S heterozygotes, a result consistent with the view that P and S occupy corresponding positions in homologous chromosome segments. Rr reconstitution was detected in both tandem duplication heterozygotes P s/S and P/p S, and was found to be about ten times more frequent in the latter. The ratio of Rr reconstitution in the two heterozygotes is a function of position of the anthocyanin marker within the duplicated segment. The data from these heterozygotes allow one to measure the distance between P and S, that is to say, the genetic length of the duplicated segment. This distance was found to be 0.16 map units. The highest frequency of Rr reconstitution was obtained from P s/p S heterozygotes, since direct pairing (see PDF) as well as the p//s type of displaced pairing have the potential to produce Rr derivatives. One of the Rg derivatives used in this study, Rg 6, was found to back-mutate in some sublines to Rr. The basis for this instability remains unknown.
GENETIC STRUCTURE OF A POPULATION OCCUPYING A CIRCULAR HABITAT
Authors: Nagylaki Thomas 
Published: January 2021

ABSTRACT
The geographical structure of a finite population distributed continuously and homogeneously along a circular habit is explored. Selection is supposed to be absent, and the analysis is restricted to a single locus with discrete, non-overlapping generations. Assuming every mutant is new to the population, the rate of decay of genetic variability is obtained, and the probability that two homologous genes separated by a given distance are different alleles is calculated. If moments of the migration function higher than second are neglected, the eigenvalue equation is shown to be a simple trigonometric one, and the Fourier series giving the transient and stationary probabilities of allelism are summed in terms of elementary functions. The proportion of homozygotes, the effective number of alleles maintained in the population, and the amount of local differentiation of gene frequencies are discussed.