bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENETIC AND BIOCHEMICAL BASIS OF ENZYME ACTIVITY VARIATION IN NATURAL POPULATIONS. I. ALCOHOL DEHYDROGENASE IN DROSOPHILA MELANOGASTER
Authors: McDonald John F , Ayala Francisco J 
Published: April 2021

ABSTRACT
Recent studies by various authors suggest that variation in gene regulation may be common in nature, and might be of great evolutionary consequence; but the ascertainment of variation in gene regulation has proven to be a difficult problem. In this study, we explore this problem by measuring alcohol dehydrogenase (ADH) activity in Drosophila melanogaster strains homozygous for various combinations of given second and third chromosomes sampled from a natural population. The structural locus (Adh) coding for ADH is on the second chromosome. The results show that: (1) there are genes, other than Adh, that affect the levels of ADH activity; (2) at least some of these "regulatory" genes are located on the third chromosome, and thus are not adjacent to the Adh locus; (3) variation exists in natural populations for such regulatory genes; (4) the effect of these regulatory genes varies as they interact with different second chromosomes; (5) third chromosomes with high-activity genes are either partially or completely dominant over chromosomes with low-activity genes; (6) the effects of the regulatory genes are pervasive throughout development; and (7) the third chromosome genes regulate the levels of ADH activity by affecting the number of ADH molecules in the flies. The results are consistent with the view that the evolution of regulatory genes may play an important role in adaptation.
EXPLORING THE POTENTIAL OF COMPOUND;FREE-ARM COMBINATIONS OF CHROMOSOME 2 IN DROSOPHILA MELANOGASTER FOR INSECT CONTROL AND THE SURVIVAL TO PUPAE OF WHOLE-ARM TRISOMIES
Authors: Fitz-Earle M , Holm D G 
Published: April 2021

ABSTRACT
Genetic tests of second-chromosome compound;free-arm combinations ("free arms") in Drosophila melanogaster indicate that the egg hatch is approximately 50% that of standard lines and adult recovery is approximately 40%. Free-arm strains are genetically isolated from both compound-chromosome lines and standards.
A large proportion of the hybrid progeny arising from crosses between free arms and standards or free arms and compounds, survive to the pupal stage. Cytological examinations reveal that these hybrids are trisomic for one arm of chromosome 2. Such hybrid progeny may place an added constraint upon the competition between free-arm and standard strains by competing for food, but not contributing to the adult population. The fitness data, the genetic isolation characteristic and the possible impact of hybrid progeny all suggest that free arms may prove to be a valuable genetic tool for insect population control. Preliminary cage-competition experiments to test this prediction have demonstrated that free arms are able to displace standards at ratios as low as 3:1, which is close to the theoretical equilibrium predicted by the fitness data (2.5:1).
GENETICS OF HEMOGLOBIN IN THE DEER MOUSE, PEROMYSCUS MANICULATUS. I. MULTIPLE α- AND β-GLOBIN STRUCTURAL LOCI
Authors: Snyder Lee R G 
Published: April 2021

ABSTRACT
Genetic data, together with molecular structure studies, have demonstrated that the complex hemoglobin phenotypes in four subspecies of P. maniculatus are generated by at least four, and probably five, globin structural loci. The Hba and Hbc loci apparently arose by duplication of an ancestral α-type locus, while Hbb, Hbd, and Hbe apparently were derived from a β-type locus. The Hba and Hbb structural loci are electrophoretically monomorphic, while Hbc, Hbd, and Hbe are each polymorphic for at least two electrophoretic alleles. Alleles at Hbc and Hbd segregate independently. The globin products of Hbc and Hbd are electrophoretically indistinguishable; therefore, it is impossible to enumerate true gene frequencies in population surveys. Combined evidence from Peromyscus, Mus and Rattus indicates a remarkable similarity in the numbers of duplicated globin structural loci and in their linkage relationships to coat color loci.
GENETIC VARIATION IN ACTIVITY OF THE ENZYMES OF GLYCOLYSIS AND GLUCONEOGENESIS BETWEEN INBRED STRAINS OF MICE
Authors: Bulfield Grahame , Moore Elizabeth A , Kacser Henrik 
Published: April 2021

ABSTRACT
Variation in the activity of 21 liver and 15 erythrocyte enzymes between seven inbred strains of mice has been studied in a single area of metabolism, glycolysis and gluconeogenesis. Most of the variation between the strains is genetic. From the variation within and between inbred strains heritabilities (H 2) were determined. Out of 35, 26 showed significant values above 0.4. A comparison with previously published work suggests that enzyme activities have mainly dominance and interaction components of variance, and this is discussed in relation to the variation in quantitative characters such as growth. In nine of the pairwise comparisons of the strains, the activity of the enzyme varied more than two-fold. In these cases the genetics and biochemistry of the enzyme was studied; F2 progeny were produced and assessed for segregation, and the heat stability of the enzyme was determined. No unequivocal segregation was observed, although in one case we found a considerable difference in heat stability. The variations found were not considered to be great enough to be useful as models of human inborn errors of metabolism or to study metabolic control. If such variants are to be found, sources of variation other than inbred strains must be used.
RENEWAL PROCESS APPROACH TO THE THEORY OF GENETIC LINKAGE: CASE OF NO CHROMATID INTERFERENCE
Authors: Cobbs Gary 
Published: April 2021

ABSTRACT
Models are presented in which the distribution of crossovers at a four-four-strand stage of meiosis results from a renewal process. Probability distributions are obtained for the number of crossover events on a meiotic bivalent and for the number of exchange points in random meiotic products. These distributions are found to fit the observed distribution of these variables reasonably well. Using these distributions and assuming no chromatid interference, relations between map distance and the recombination fraction are obtained. These relations give either better or equivalent fit to data when compared to relations that are designed to account for both chromatid and chiasma interference.
THE SPATIAL DISTRIBUTION OF TRANSIENT ALLELES IN A SUBDIVIDED POPULATION: A SIMULATION STUDY
Authors: Slatkin Montgomery , Charlesworth Deborah 
Published: April 2021

ABSTRACT
The spatial distributions of newly introducted alleles in a subdivided population are generated using a computer program to model the processes of selection, gene flow and genetic drift. Advantageous, neutral and deleterious alleles are considered, and certain aspects of the patterns generated by new alleles that are ultimately fixed and ultimately lost are examined. To characterize the spatial pattern of rare alleles, the distribution, Pi, the probability that the new allele is found in exactly i local populations before it is lost, is defined and estimated from the simulations. The shape of the Pi distribution is surprisingly similar for selected and neutral alleles. For advantageous alleles going to fixation, the "wave of advance" is set up quickly, but stochastic effects reduce the wave speed from Fisher's (1937) value. Gene flow is much more effective in dispersing alleles in a two-dimensional array than in one dimension. Long distance gene flow has a much smaller effect in two dimensions than in one dimension.
MUTANTS OF SEXUAL MATURITY IN PARAMECIUM CAUDATUM SELECTED BY ERYTHROMYCIN RESISTANCE
Authors: Myohara Koji , Hiwatashi Koichi 
Published: April 2021

ABSTRACT
Cells of Paramecium caudatum, syngen 3 usually become sexually mature about 50 fissions after conjugation. In order to study the genetic mechanisms that control fission-dependent expression of maturity, an attempt was made to obtain early mature mutants by treatment with N-methyl-N′-nitro-N-nitro-soguanidine. A new cytoplasmic marker, erythromycin resistance, was used to eliminate nonconjugant and macronuclear regeneration clones. Twenty early mature clones were obtained from five different mutagenized cultures. Three of them were genetically analyzed by crosses to wild-type stocks. The results show all three mutants to be controlled by incompletely dominant genes, i.e., the homozygotes became mature 20-25 fissions and the heterozygotes 15 fissions earlier than the wild-type clones. At least two different loci are suggested for the early maturity.
CYTOGENETIC ANALYSIS OF CHROMOSOME 3 IN DROSOPHILA MELANOGASTER: ISOLATION AND CHARACTERIZATION OF FOUR NEW ALLELES OF THE PROBOSCIPEDIA (pb) LOCUS
Authors: Kaufman Thomas C 
Published: April 2021

ABSTRACT
Previous studies on proximal 3R have cytologically localized the dominant homeotic loci Antennapedia (Antp), Multiple Sex Comb (Msc), Nasobemia (Ns), and Extra Sex Comb (Scx). In this study we set out to find the site of the proboscipedia (pb) locus. In order to accomplish this, four new alleles of this homeotic gene were induced with gamma rays. Genetic and cytogenetic analyses have shown that the pb locus resides in polytene chromosome bands 84A1-6, immediately adjacent to the Antp gene complex in 84B1-2. An analysis of the morphology of the proboscis and the dose relationships of the four new alleles have shown that this homeosis is unusual in at least two respects. First, the two different developmental fates realized in the proboscis at 18° (labial palps → arista) and 29° (labial palps → leg) under the influence of pb1 grown at 18°, while the remaining three are like pb 1 at 29°. Dosage studies reveal that this difference reflects a hypomorphic vs. amorphic condition. Second, like the original, these new alleles produce a prothoracic rather than a mesothoracic leg in the proboscis. Both of these results indicate that pb is unique among the homeotics, and as such it may offer some new insights into developmental processes.
DYNAMICS OF CORRELATED GENETIC SYSTEMS. IV. MULTILOCUS EFFECTS OF ETHANOL STRESS ENVIRONMENTS
Authors: Cavener D R , Clegg M T 
Published: April 2021

ABSTRACT
Four replicate populations of Drosophila melanogaster, two reared on medium supplemented with ethanol and two reared on standard medium, were electrophoretically monitored for 28 generations. During the first 12 generations, allelic, genotypic and gametic frequencies were determined for eight polymorphic enzymes: GOT, α-GPDH, MDH, ADH, TO, E6, Ec and ODH. Samples from generation 18 and 28 were electrophoretically typed for ADH and α-GPDH. In addition, samples from generation 27 were analyzed for the presence of inversion heterozygous.—The experimental results showed rapid gene-frequency divergence between control and treatment populations at the Adh locus in a direction consistent with the activity hierarchy of Adh genotypes. Gene-frequency divergence between control and treatment populations also occurred at the α-Gpdh locus, although the agreement among replicates appeared to have broken down by generation 28. No differential gene-frequency change occurred at any of the six remaining marker loci. Furthermore, values of linkage disequilibria among all linked pairs of genes were initially small and remained small throughout the course of the experiment. Taking these facts into account, it is argued that the gene-frequency response observed at ADH is most probably caused by selection at the Adh locus. The gene frequency response at α-Gpdh can also be be accounted for in terms of the effect of ethanol on energy metabolism, although other explanations cannot be excluded.
REGULATION OF NEWLY EVOLVED ENZYMES. IV. DIRECTED EVOLUTION OF THE EBG REPRESSOR
Authors: Hall Barry G 
Published: April 2021

ABSTRACT
In Escherichia coli, the wild-type repressor of ebg (evolved β-galactosidase) enzyme synthesis, specified by the ebgR + gene, responds very weakly to lactulose (fructose-β-D-galactopyranoside). Selection for a functional repressor that responds strongly to lactulose as an inducer reveals the existence of ebgR+L mutants, which occur spontaneously at a frequency of about 2 x 10-10. ebgR+L mutants are pleiotropic in that they specify ebg repressor with a greatly increased response to lactulose, lactose, galactose-arabinoside and methyl-galactoside as inducers. Selection of ebgR+L mutants is discussed within the framework of directed evolution of a regulatory function.
APPARENT TRANS CONTROL OF MURINE βGLUCURONIDASE SYNTHESIS BY A TEMPORAL GENETIC ELEMENT
Authors: Meredith Susan A , Ganschow Roger E 
Published: April 2021

ABSTRACT
A difference in the heat-inactivation kinetics between the β-glucuronidases of C3HeB/FeJ and C57Bl/6J mice was utilized to assess the mode of action of a temporal genetic element in controlling the expression of the β-glucuronidase structural gene Gus. The heat-inactivation kinetics of liver and kidney β-glucuronidase from F1 C3HeB/FeJ x C57Bl/6J animals were intermediate with respect to the parental enzyme patterns, suggesting that equal concentrations of the two allelic products were present in β-glucuronidase tetramers of F1 progeny. β-glucuronidase heteropolymers assembled in vivo under conditions where equal concentrations of the two structural alleles of the enzyme were known to be present also exhibited intermediate heat-inactivation kinetics. These observations are consistent with a trans mode of action of a genetic element that controls the rate of murine β-glucuronidase synthesis.
THE RELATIONSHIP BETWEEN SYNAPTINEMAL COMPLEXES, RECOMBINATION NODULES AND CROSSING OVER IN NEUROSPORA CRASSA BIVALENTS AND TRANSLOCATION QUADRIVALENTS
Authors: Gillies C B 
Published: April 2021

ABSTRACT
Reconstruction of serially sectioned zygotene and pachytene nuclei has allowed the estimation of both the number and position of central component recombination nodules in the synaptinemal complexes of two chromosomally different strains of Neurospora crussa. In both strains the number of nodules is that expected if each nodule represents one crossover event (50 map units). The distribution of nodules within the arms of bivalents shows evidence of centromeric repulsion and telomeric localizatioa. Nodules appear quite early in the zygotene before pairing of chromosomes is complete. Evidence was found of size differences in nodules, and multiple nodules were occasionally seen. Chromosome lengths and nuclear sizes increased from early zygotene to late pachytene. The three quadrivalents present in the alcoy translocation heterozygotes were readily distinguishable in reconstructions, and their cytological dimensions were in agreement with predictions from linkage map distances.
X-RAY STAGE SENSITIVITY OF MOUSE OOCYTES AND ITS BEARING ON DOSE-RESPONSE CURVES
Authors: Brewen J G , Payne H S 
Published: April 2021

ABSTRACT
A detailed cytogenetic study of maturing mouse oocyte radiosensitivity was performed. Oocytes were collected at various intervals ranging from 1.5 days to 28.5 days after irradiation with 50, 100, 200, and 300R of acute X-rays. The observed sensitivity to chromatid aberration induction varied greatly over this time span. Sensitivity was lowest at the shortest time interval before ovulation and gradually increased up to 9.5 days; it then remained constant until insufficient numbers of oocytes could be collected. The data were analyzed in three ways. First, the data from all time intervals at each dose were pooled; second the data from the least sensitive time intervals, at each dose, were pooled, and third, the data from the period of uniform sensitivity, at each dose, were pooled. Dose-response regression analyses were done on these pooled data and the best fits obtained were to the models Y= a + bD + cD2 and Y= a + cD2 for both deletions and interchanges. This result is interpreted as indicating that the aberrations result from a predominantly two-track process. The cytogenetic data were compared to specific-locus mutation induction data in comparable oocyte stages, and qualitative similarity in dosei esponse characteristics were observed. This similarity is interpreted to mean that both events result from the same mechanism, and that the large dose-rate effect, observed for both events, is a reflection of the two-track component in the dose-response curves.
GENETIC ORGANIZATION IN CAENORHABDITIS ELEGANS: FINE-STRUCTURE ANALYSIS OF THE unc-22 GENE
Authors: Moerman D G , Baillie D L 
Published: April 2021

ABSTRACT
Fine-structure analysis of the unc-22 gene of Caenorhabditis elegarns has revealed a number of sites that are separable by recombination. Eight new ethyl methanesulfonate-induced recessive mutations of the unc-22 gene have been isolated. Using these new alleles, as well as e66, a number of separable sites have been identified and positioned relative to one another. The map distances obtained are found to be comparable to those associated with intragenic recombination in Drosophila melanogaster, indicating that genetic finestructure analysis is feasible in Caenorhabditis elegans. Evidence of possible gene conversion is presented. A preliminary estimate of the unc-22 gene size is 2.4 × 10-2 map units.
FUNCTIONAL INTERACTIONS BETWEEN THE DNA LIGASE OF ESCHERICHIA COLI AND COMPONENTS OF THE DNA METABOLIC APPARATUS OF T4 BACTERIOPHAGE
Authors: Karam J D , Leach M , Heere L J 
Published: April 2021

ABSTRACT
T4 phage completely defective in both gene 30 (DNA ligase) and the rll gene (function unknown) require at least normal levels of host-derived DNA ligase (E. coli lig gene) for growth. Viable E. coli mutant strains that harbor less than 5% of the wild-type level of bacterial ligase do not support growth of T4 doubly defective in genes 30 and rll (T4 30- rll- mutants). We describe here two classes of secondary phage mutations that permit the growth of T4 30- rll- phage on ligase-defective hosts. One class mapped in T4 gene su30 (KRYLO1V9 72) and improved T4 30- rll- phage growth on all E. coli strains, but to varying degrees that depended on levels of residual host ligase. Another class mapped in T4 gene 32 (heliz-destabilizing protein) and improved growth specifically on a host carrying the lig2 mutation, but not on a host carrying another lig- lesion (lig4). Two conclusions are drawn from the work: (1) the rde of DNA ligase in essential DNA metabolic processes in T4-infected E. coli is catalytic rather than stoichiometric, and (2) the E. coli DNA ligase is capable of specific functional interactions with components of the T4 DNA replication and/or repair apparatus.
EXPANDED LINKAGE MAP OF VIBRIO CHOLERAE
Authors: Parker Charlotte , Gauthier Dorothy , Tate Ann , Richardson Katie , Romig W R 
Published: April 2021

ABSTRACT
An expanded linkage map of the Vibrio cholerae classical strain 162 chromosome has been prepared using a variety of new auxotrophic mutants. The chromosome consists of a single, linear linkage group. The map consists of 17 markers, which have been ordered; 20 mutational sites, which are tentatively ordered; five markers (ura-1, ser-2, mal-1, man-1, suc-1), which are linked but unordered; and three mutations (aro-2, cys-2 and cys-6) which showed little or no linkage. A proposal is made to standardize genetic nomenclature in V. cholerae genetic studies.
A PRELIMINARY GENETIC INVESTIGATION OF VOLVOX CARTERI
Authors: Huskey Robert J , Griffin Barbara E , Cecil Patricia O , Callahan Ann M 
Published: April 2021

ABSTRACT
A preliminary genetic analysis of a number of genetic variants of Volvox carteri f. nagariensis is presented. Techniques are outlined for mutagenesis of Volvox, isolation of mutants and routine genetic analysis. All of the mutants show simple Mendelian segregation patterns and have been tentatively placed in 14 linkage groups.
USE OF TWO-DIMENSIONAL ELECTROPHORESIS TO IDENTIFY AND MAP NEW MOUSE GENES
Authors: Elliott Rosemary W 
Published: April 2021

ABSTRACT
Cytosol polypeptides from mouse liver have been examined using twodimensional electrophoresis. About 250 spots were readily discernible. When cytosols from strains BALB/cBy and C57BL/6By were compared, eight genetically determined differences were observed. Other strain pairs show comparable numbers of differences. These eight phenotypes were scored in seven recombinant inbred lines derived from the two parental strains, and their strain distribution patterns were compared with previously determined patterns for other genetic markers that differ between the two progenitor strains. Using this information, tentative chromosome assignments for the genes controlling five of the variant phenotypes have been made, and two of the assignments have been confirmed using congenic resistant strains. These eight genes will be useful reference markers in fiiture crosses designed to map new genes.
BEHAVIORAL MUTANTS IN PARAMECIUM CAUDATUM
Authors: Takahashi Mihoko 
Published: April 2021

ABSTRACT
Mutants of Paramecium caudatum with abnormal swimming behavior or responses to cations were obtained by mutagenesis with N-methyl-N-nitro N-nitrosoguanidine. Some of the mutants, like pawn in P. tetraurelia, cannot swim backward and are called CNR. Seven independently obtained CNR mutants belonged to three complementation groups, designated as cnrA, cnrB and cnrC. Some characteristics of double homo- and heterozygotes were compared with single homo- and heterozygotes. Other behavioral mutants shown to have a genic basis included K+-sensitive, temperature-shack behavioral and slow swimmer. All those mutants except for slow swimmer had lesions in the membrane because Triton-extracted models of them show almost the same swimming behavior as wild type.
NON-MENDELIAN FEMALE STERILITY IN DROSOPHILA MELANOGASTER: PRINCIPAL CHARACTERISTICS OF CHROMOSOMES FROM INDUCER AND REACTIVE ORIGIN AFTER CHROMOSOMAL CONTAMINATION
Authors: Picard Georges 
Published: April 2021

ABSTRACT
Strains of Drosophila melanogaster can be divided into two main classes, inducer and reactive, in relation to non-Mendelian female sterility. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i + chromosome) can produce females showing more-or-less reduced fertility when it is introduced by paternal gametes into a reactive oocyte. As long as i+ chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor strictly follows Mendelian segregation. In contrast, in heterozygous i+/r females, a varying proportion of r chromosomes may acquire I factor independently of classical genetic recombination, by a process called chromosomal contamination. This paper reports investigation of the characteristics of the three kinds of chromosomes produced by females in which contamination occurs. It appears that the contaminated reactive chromosomes have irreversibly acquired I factor and behave like i + chromosomes, while the i + chromosomes used as contaminating elements and the reactive originating chromosomes that have not been contaminated have not undergone any change.
FREQUENCY-DEPENDENT SELECTION FOR PLASMID-CONTAINING CELLS OF ESCHERICHIA COLI
Authors: Adams Julian , Kinney Thomas , Thompson Susan , Rubin Lori , Helling Robert B 
Published: April 2021

ABSTRACT
Colicin-producing plasmid-containing cells of E. coli exhibit frequency dependent selection when grown in glucose-limited continuous culture with the corresponding plasmid-free strain. The bases of this frequency-dependent effect are shown to be (1) the lower growth rate of the plasmid-containing strain under these conditions, and (2) the production of colicin, which attenuates the growth rate of the plasmid-free strain. These results are discussed in relationship to the maintenance of genetic variation in prokaryotes.