bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spreading Uncertainty, Shrinking Birth Rates: A Natural Experiment for Italy
Authors: Comolli Chiara L , Vignoli Daniele 
Published: January 2021

AbstractMany previous studies have documented the procyclicality of fertility to business cycles or labour market indicators in Western countries. However, part of the recent fertility decline witnessed since the Great Recession has been left unexplained by traditional measures. The present study advances the notion that birth postponement might have accelerated in response to rising uncertainty, which fuelled negative expectations and declining levels of confidence about the future. To provide empirical support for the causal effect of perceived uncertainty on birth rates, we focus on Italy’s sovereign debt crisis of 2011–2012 as a natural experiment. Perceived uncertainty is measured using Google trends for the term ‘spread’—which acted as somewhat of a barometer for the crisis both in the media and everyday conversations—to capture the general public’s degree of concern about the stability of Italian public finances. A regression discontinuity in time identifies the effect of perceived uncertainty on birth rates in Italy as a drop between 1.5% and 5%, depending on model specification.
LABORATORY STUDIES BEARING ON PIGMENT PATTERN POLYMORPHISMS IN WILD POPULATIONS OF RANA PIPIENS
Authors: Merrell David J 
Published: January 2021

ABSTRACT
Data are presented for 2,393 progeny from a number of crosses related to a study in ecological genetics of the Burnsi and Kandiyohi polymorphisms in natural populations of the leopard frog, Rana pipiens. No significant differences in viability were found between wild-type homozygotes (+/+) and Burnsi heterozygotes (B/+) or homozygotes (B/B). Similarly, no difference in viability was found between wild-type (+/+) and Kandiyohi heterozygotes (K/+) and homozygotes (K/K). However, there appears to be slight reduction in viability of the double dominant heterozygote (B/+; K/+) in comparison with (+/+), (B/+), and (K/+) progeny from the same cross.—The Kandiyohi heterozygotes (K/+) appeared to have a more rapid rate of development from fertilization through metamorphosis than wild-type (+/+) or Burnsi (B+/) or Burnsi-Kandiyohi heterozygotes (B+K/+). Since Kandiyohi is associated primarily with the prairie habitat (Merrell 1965), this finding suggests that the adaptive advantage of Kandiyohi lies in the more rapid rate of development of frogs carrying this gene, enabling them to complete metamorphosis before the prairie breeding ponds dry up.—Data are presented from crosses involving dorsal spot number. The results suggest that heredity plays a role in the determination of dorsal spot number but that non-genetic influences are also of considerable importance.—The results of these crosses are discussed with respect to their bearing on the formation of pigment patterns in Rana pipiens. From the available data it is clear that the pigment pattern in Rana pipiens is a complex trait influenced by major gene loci, by modifying genes, and by environmental effects. The relative importance of these factors varies depending on the particular combination of genetic and environmental conditions.
ENZYME VARIABILITY IN THE DROSOPHILA WILLISTONI GROUP. III. AMOUNTS OF VARIABILITY IN THE SUPERSPECIES, D. PAULISTORUM
Authors: Richmond Rollin C 
Published: January 2021

ABSTRACT
The semispecies composing the superspecies, Drosophila paulistorum, have been analyzed for genetic variation at 17 enzyme loci. On the average a population of D. paulistorum is polymorphic for 55–67% of its loci and an average individual is heterozygous at 21% of its loci. The pattern of genetic variability found supports the hypothesis that allozyme variation is maintained in natural populations by some form of balancing selection. Evidence is presented which supports the hypothesis that glucose-metabolizing enzymes are less genetically variable than non-glucose-metabolizing enzymes. The known genetic relationships between the semispecies of D. paulistorum are discussed in the light of the frequencies of alleles at allozyme loci.
ON THE GENETIC CONTROL OF GENES LOCATED IN THE SEX-CHROMOSOME HETEROCHROMATIN OF DROSOPHILA MELANOGASTER
Authors: Sandler L 
Published: January 2021

ABSTRACT
The genetic properties of a recessive autosomal point mutant, "daughterless" (symbol: da), are described. They are: (1) da maps in the euchromatin of 2L at about position 39 on the genetic map and between 27D and 31E on the salivary map; (2) when homozygous in females, da causes the production of unisexual male progenies owing to sex differential zygote mortality in the egg stage; (3) da has no effect on the progeny of mutant males; (4) female zygotes die, while at least some male zygotes survive, irrespective of the number of Y chromosomes or the amount of X-chromosome heterochromatin carried by either the mutant female or her progeny; (5) homozygous da progeny of heterozygous parents also show sex differential survival favoring males indicating a da effect in development as well as in oogenesis, but with the developmental effect much less pronounced; (6) extra heterochromatin from either the X or Y chromosome in either the mother or her progeny can reduce the mortality caused by da in development (and, therefore, conceivably can also reduce the abnormality in oogenesis, although this is obscured by the seventy of the maternal effect.)——From these results, it is suggested that (1) da regulates either the activity of structural genes in the sex chromosome heterochromatin or the activity or stability of their products, and (2) it is a defective product of sex chromosome heterochromatic genes that causes the abnormalities resulting in the observed mortality of heterozygous progeny of homozygous mutant m3thers and of homozygous mutant progeny of heterozygous mothers.——The striking parallels with the properties of the gene, "abnormal oocyte" are noted as is the close linkage between the two loci. The possibility of a special sex-chromosome-heterochromatin-regulator region on chromosome 2 is considered.
INTERACTIONS OF DIFFERENTIATED PRIMARY SEX FACTORS IN CHIRONOMUS TENTANS
Authors: Thompson Peter E , Bowen Jean S 
Published: January 2021

ABSTRACT
Different populations of Chironomus tentans, possibly representing geographically isolated races, have two differentiated genic mechanisms of sex determination involving either a dominant male-determining factor in the left arm of chromosome 1 or a dominant female-determining factor at the right tip of chromosome 1. In crosses between these populations, the male-determining factor is epistatic to the female-determining factor. No evidence of intersexuality has been found in such crosses.
EXTRACHROMOSOMAL ELEMENT DELTA IN DROSOPHILA MELANOGASTER. VII. RELATION TO FERTILITY IN A SECOND-CHROMOSOME LINE
Authors: Minamori Sumio , Ito Kazuko 
Published: January 2021

ABSTRACT
The IDb-45 chromosome line usually carries an appreciable amount of delta b, but it is not susceptible to the killing action of this delta. The fertility of this line was examined when it carried various amounts of delta b. More than one third of the Cy/IDb-45 males and females tested became sterile when they carried cytoplasm of the Cy/Pm stock which is assumed to carry no delta b. The number of progeny is smaller when flies of this line are raised at 25°C than at 28°C at which temperature the multiplication of delta is accelerated. The progeny number was appreciably reduced when the flies were raised at 18°C at which temperature the multiplication of delta is suppressed. This line could not be maintained at that temperature, since both males and females became sterile. Thus, the conclusion may be drawn that the presence of an appreciable amount of delta b is necessary for the gametogenesis of the Cy/IDb-45 flies.
GENETICS OF SOMATIC FUSION IN PHYSARUM POLYCEPHALUM: THE PpII STRAIN
Authors: Collins O'Neil Ray , Haskins Edward F 
Published: January 2021

ABSTRACT
Plasmodial (somatic) fusion in a strain of Physarum polycephalum, a true slime mold, is controlled by four loci, each of which displays simple dominance. Two diploid plasmodia fuse with each other only if they are phenotypically or genotypically identical for all four fusion loci.
THE EFFECT OF ABNORMAL CHROMOSOME 10 ON TRANSPOSITION OF MODULATOR FROM THE R LOCUS IN MAIZE
Authors: Williams Elizabeth , Brink R Alexander 
Published: January 2021

ABSTRACT
Transposition of the non-specific repressor element, Modulator, from the R locus on chromosome 10 in maize, is enhanced by coupling with the K10 segment at a distance of at least 35 map units from R. There is no detectable interaction in the repulsion phase. The K10 effect appears to be relatively greater in the earlier somatic cell generations during ear development. The transposition rate also is affected by the direction of crosses, being somewhat higher on the ears of F1 plants which received the compound mutable R allele from the pollen parent. The significance of the behavior of Modulator and other instability phenomena of higher plants is discussed in relation to chromosome organization.
ISOLATION OF PLAQUE-FORMING, GALACTOSE-TRANSDUCING STRAINS OF PHAGE LAMBDA
Authors: Feiss Michael , Adyha Sankar , Court Donald L 
Published: January 2021

ABSTRACT
Plaque-forming, galactose-transducing lambda strains have been isolated from lysogens in which bacterial genes have been removed from between the galactose operon and the prophage by deletion mutation.—A second class has been isolated starting with a lysogenic strain which carries a deletion of the genes to the right of the galactose operon and part of the prophage. This strain was lysogenized with a second lambda phage to yield a lysogen from which galactose-transducing, plaque-forming phages were obtained. These plaque-forming phages were found to be genetically unstable, due to a duplication of part of the lambda chromosome. The genetic instability of these partial diploid strains is due to homologous genetic recombindation between the two identical copies of the phage DNA comprising the duplication. The galactose operon and the duplication of phage DNA carried by these strains is located between the phage lambda P and Q genes.
NONSENSE MUTATIONS IN THE ADE3 LOCUS OF SACCHAROMYCES CEREVISIAE
Authors: Jones Elizabeth W 
Published: January 2021

ABSTRACT
Fifty seven mutations at the ade3 locus have been crossed to ochre, amber and ochre-amber suppressors. 70% (39/56) of the mutations at this locus are nonsense mutations; 61% (34/56) are ochre mutations and 9% (5/56) are amber mutations. The frequency of nonsense mutations among ade3 alleles recovered is very high and raises the interesting possibility that only polar mutations at this locus are recovered. An hypothesis to explain these genetical findings as well as physiological properties of these mutations is proposed.
DIFFERENCES IN SYNAPTIC AFFINITY OF CHROMOSOME ARMS OF DROSOPHILA MELANOGASTER REVEALED BY DIFFERENTIAL SENSITIVITY TO TRANSLOCATION HETEROZYGOSITY1
Authors: Roberts Paul A 
Published: January 2021

Abstract
The chromosome arms of Drosophila melanogaster differ in the degree to which translocation heterozygosity suppresses crossing over both regionally, and as whole arms. We have identified the region of maximum sensitivity to structural heterozygosity in each arm of the long autosomes ⅓ to ½ the length of the arm in from the tip. We interpret the regional differences as further indication that synapsis usually begins distally, but not at the telomeres. We interpret the different sensitivity of arms 3R, 2R, 3L and 2L (ranked in order of increasing sensitivity) as evidence of intrinsic differences in the synaptic affinity of chromosome arms.
NONSENSE MUTATION IN THE REGULATORY GENE ETH2 INVOLVED IN METHIONINE BIOSYNTHESIS IN SACCHAROMYCES CEREVISIAE
Authors: Masselot M , de Robichon-Szulmajster H 
Published: January 2021

ABSTRACT
Ethionine-resistant mutants, mapping at the locus eth2—the product of which is involved in pleiotropic regulation of methionine biosynthesis—have been isolated in a strain carrying five ochre nonsense mutations. Selection for nonsense suppressors in such a strain led to characterization of several allele-specific but gene non-specific suppressors which are active on the recessive heteroallele eth2–2 (resulting in partial recovery of sensitivity toward ethionine) as well as on the five other suppressible alleles. Two of these suppressors are unlinked to the eth2 gene and either dominant or semi-dominant. It is concluded that the mutation eth2–2 resulted in a nonsense codon. Enzyme studies indicate that this mutation results in a complete absence of an active product of gene eth2, in contrast with the effect of a former mutation eth2–1 which was interpreted as leading to a modified product of this gene (Cherest, Surdin-Kerjan and de Robichon-Szulmajster 1971). This conclusion is based on the absence of repressibility of methionine group I enzymes and the observation that in a heteroallelic diploid, eth2–1 expression is not masked by eth2–2. The nonsense suppressors studied lead to at least partial recovery of repressibility of methionine group I enzymes. All these results support the idea that the product of gene ETH2 is an aporepressor protein.
INHERITANCE DURING PARTHENOGENESIS IN DAPHNIA MAGNA
Authors: Hebert P D N , Ward R D 
Published: January 2021

ABSTRACT
Natural populations of Daphnia magna have been found which are polymorphic for electrophoretic variants of supernatant malic dehydrogenase, esterase, and alkaline phosphatase. Using these enzyme variants as genetic markers it has been possible to demonstrate the absence of recombination during parthenogenetic reproduction. Genetic uniformity is expected within parthenogenetic clones derived from a single female.
CHARACTERIZATION OF CHICKEN b-LOCUS (IgG) ALLOTYPES
Authors: David C S 
Published: January 2021

ABSTRACT
Chicken allotypes b1 and b2 are controlled by allelic genes and associated with the IgG class of immunoglobulins. The determinants cannot be detected on either isolated heavy and light polypeptide chains or the enzymatic fragments. The results suggest that either the intact IgG molecule is required for their expression or the conditions normally used for isolation of the subunits destroy or modify the antigenic specificities in chickens.
A MODEL FOR THE GENETICS OF HANDEDNESS
Authors: Levy Jerre , Nagylaki Thomas 
Published: January 2021

ABSTRACT
Experimental data and theoretical work on the inheritance of handedness and cerebral dominance are reviewed. A two-gene, four-allele model, one locus pertaining to left or right hemispheric dominance and the other to contralateral or ipsilateral hand control relative to the dominant hemisphere, is constructed. It is in excellent agreement with all quantitative information regarding this problem. Refinements designed to explain relevant qualitative facts are proposed and discussed.
DIRECT EVIDENCE OF GENIC DIFFERENTIATION BETWEEN SEX RATIO AND STANDARD GENE ARRANGEMENTS OF X CHROMOSOME IN DROSOPHILA PSEUDOOBSCURA
Authors: Prakash Satya , Merritt R B 
Published: January 2021

ABSTRACT
Evidence of strong association of alleles at the Esterase-5 and adult Acid phosphatase-6 loci with the Sex Ratio and the Standard X chromosome arrangements in D. pseudoobscura is presented. There is no differentiation at these two loci, either in the Sex Ratio or the Standard arrangement from two widely separated geographic populations. At the Esterase-5 locus, alleles characteristic of one arrangement are found in low frequencies in the other arrangement. It is concluded, from these and other observations that the differentiation between the Sex Ratio and the Standard arrangement, at these two loci, is a result of natural selection favoring different coadapted gene blocks in these arrangements. The average heterozygosity at these two loci in different karyotypes is in the following order: ST/SR &gt; ST/ST &gt;&gt; SR/SR which agrees very well with the fitness estimates of these karyotypes.
TRANSITORY HETEROSIS IN NUMBERS OF BASAL BODIES IN TETRAHYMENA PYRIFORMIS
Authors: Nanney D L , Doerder F P 
Published: January 2021

ABSTRACT
The numbers of kinetosomes in ciliary rows on the ventral surface of cells of Tetrahymena pyriformis, syngen 1, are greater by about 10% in young heterozygotes established by crossing two inbred strains than in either homozygote. The difference, apparent at 20 fissions post-fertilization, is essentially gone by 100 fissions. This observation is consistent with a generalized "allelic exclusion" at all loci completed by perhaps 60 fissions after fertilization.
GENETIC MAP OF THE LACTOSE REPRESSOR GENE (i) OF ESCHERICHIA COLI
Authors: Pfahl Magnus 
Published: January 2021

ABSTRACT
39 tonB i- deletions were used to map 57 independently isolated i gene mutants. Methods selective for i+ recombinants from various types of i mutants are described. i+ recombination frequencies of 6 × 10-6 to 6 × 10-7 can be detected in the different selective systems. Twenty i s mutations and 12 i -d mutations map in distinct but different regions of the gene. i - sus mutations are scattered over the gene.
SATELLITE DNAs IN THE EMBRYOS OF VARIOUS SPECIES OF THE GENUS DROSOPHILA
Authors: Travaglini E C , Petrovic J , Schultz J 
Published: January 2021

ABSTRACT
A tentative evolutionary pattern has been found for two classes of the multiple satellite DNA's found in the genus Drosophila. The satellite DNA's from five Drosophila species (D. melanogaster, D. simulans, D. nasuta, D. virilis and D. hydei) were analyzed and found to fall into three arbitrary CsCl buoyant density classes: Class I, ρ = 1.661-1.669 g cm-3, DNA molecules composed of primarily dA and dT moieties; Class II, ρ = 1.685 and ρ = 1.692, DNA molecules of low GC content; and Class III, ρ = 1.711, a DNA of high GC composition. The dAT satellite DNA's appear in all the species studied except D. hydei, the species of most recent evolutionary divergence, whereas the heavy satellite appears only in the two species of most recent divergence, D. virilis and D. hydei.
ANALYSIS OF COMPLEX ALLOZYME POLYMORPHISMS IN A BARLEY POPULATION
Authors: Weir B S , Allard R W , Kahler A L 
Published: January 2021

ABSTRACT
Genotypes of 68,230 individuals taken from 10 generations (F4-F6, F14-F17, F24-F26) of an experimental population of barley were determined for four esterase loci. The results show that frequencies of gametic ditypes changed significantly over generations and that striking gametic phase disequilibrium developed within a few generations for each of the six pairwise combinations of loci which were monitored. The complex behavior of these four enzyme loci in the population is attributed to interactions between selection and restriction of recombination resulting from the effects of linkage and/or inbreeding.
INFLUENCE OF BACKGROUND GENOME ON ENZYMATIC CHARACTERISTICS OF YELLOW (Ay/-, Avy/-) MICE
Authors: Wolff George L , Pitot Henry C 
Published: January 2021

ABSTRACT
dentification of the fundamental polypeptide difference between yellow (Ay/-, Avy/-) and non-yellow mice is important for biomedical research because of the influence of the yellow genotype on normal and neoplastic growth and obesity. The complexity of the "yellow mouse syndrome" makes attainment of this objective dependent on the separation of those pleiotropic enzyme differences which are secondary, and depend on the background genome, from those which are primary, and depend primarily on the agouti locus genotype.—Four of nine hepatic enzyme activities assayed simultaneously differed between eight-week-old yellow (Ay/-, Avy/-) and non-yellow (A/-, a/a) male inbred and F1 hybrid mice. Among these four, only cytoplasmic malic enzyme activity was elevated in all yellow mice, as compared with the non-yellow sibs, regardless of background genome. Glucokinase, serine dehydratase, and tyrosine α-ketoglutarate transaminase activities were also changed in yellow mice, but these alterations depended on the background genome.—The ratio of malic enzyme activity to citrate-cleavage enzyme activity, possibly related to the altered fat metabolism of yellow mice, was influenced by background genome as well as by the yellow genotype.—Significant deviations of enzyme activities from mid-parent values among F1 hybrids were associated with particular background genomes; the number of such deviations was larger among yellow mice than among non-yellows and this difference was greater among C3H F1 hybrids than among C57BL/6 F1 hybrids.
GENOTYPE-TEMPERATURE INTERACTION IN DROSOPHILA MELANOGASTER. II. BODY WEIGHT
Authors: Fontdevila Antonio 
Published: January 2021

ABSTRACT
The effect of genotype-temperature interactions on body weight has been studied in a natural population of Drosophila melanogaster using four isogenic strains derived from it, and their hybrid F1 and F2 progenies. Measurements were made at four constant temperatures–25°, 21°, 17° and 13°C—and at a temperature oscillating between 17° and 25°C.—Low, though significant, genotype-temperature interaction exists among the isogenic strains, but not among the F1 nor F2 hybrid progenies. These low interaction values may be due to the fact that all isogenic strains have a common origin and therefore presumably little genic divergence exists among them. F1 and F2 hybrid progenies generally exhibit higher homeostasis than the isogenic strains, although one isogenic line has better homeostasis than the majority of the hybrids.—There is no evidence of heterosis and some evidence of dominance. These results are consistent with the hypothesis that body weight is regulated mainly by additive genetic factors and is subject to stabilizing selection.
PRE-MEIOTIC DNA SYNTHESIS AND RECOMBINATION IN CHLAMYDOMONAS REINHARDI
Authors: Chiu S M , Hastings P J 
Published: January 2021

ABSTRACT
The time of the pre-meiotic S-period was determined by 32P incorporation in synchronously germinating zygospores of Chlamydomonas reinhardi at six and one-half to seven hours after the beginning of germination. Phenethyl alcohol treatment caused death of zygospores at a period one hour before the S-period, and also during meiotic prophase. Recombination between arg-1 and arg-2 was increased by treatment with phenethyl alcohol or mitomycin C at a time between the first sensitive period to phenethyl alcohol and the S-period. Actinomycin D caused an increase in recombination at the time of this sensitive period. FUdR, nalidixic acid and hydroxurea all cause a decrease in recombination when applied during S-period, and have no effect earlier. These results are explained by postulating (1) that the units of delayed premeiotic replication are whole replicons, and (2) that the amount of recombination is proportional to the number of replicons in which synthesis is delayed. It is suggested that the control of DNA replication controls the distribution of recombination events.
REGULATION OF RIBOSOMAL RNA GENE MULTIPLICITY IN DROSOPHILA MELANOGASTER
Authors: Tartof Kenneth D 
Published: January 2021

ABSTRACT
The ribosomal RNA (rRNA) genes of Drosophila melanogaster can undergo a disproportionate replication of their number. This occurs when the cluster of rRNA genes (rDNA) of one chromosome is maintained with a homologous chromosome that is completely or partially deficient in its rDNA. Under appropriate genetic conditions, it appears that disproportionate rDNA replication can be generated at the level of both somatic and germ line cells. In the latter case, mutants partially deficient for rDNA can increase their rRNA gene number to the wild type level and transmit this new genotype to successive generations.