bluuebunny/crossref_metadata_2025_split huggingface dataset:
REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA: IDENTIFICATION OF THE STRUCTURAL GENE FOR REPRESSIBLE ALKALINE PHOSPHATASE
Authors: Lehman John F , Metzenberg Robert L 
Published: April 2021

ABSTRACT
Five additional mutants of Neurospora crassa have been isolated that lack the repressible alkaline phosphatase. The mutations in these strains map at a previously assigned locus on Linkage Group V designated pho-2 (Gleason and Metzenberg 1974). The five new mutants, as well as three previously isolated by Gleason and Metzenberg (1974), were examined for the presence of cross-reacting material to antibody prepared against purified wild-type enzyme. Two of the mutants produced high levels of cross-reacting material, thus providing evidence that the pho-2 locus includes the structural gene for the repressible alkaline phosphatase. Two revertants were obtained from one of the mutants that contained cross-reacting material. Neither revertant produced an enzyme that could be distinguished physicochemically from that of wild type. A method for measuring very low levels of repressible alkaline phosphatase in crude extracts is also described.
HETEROZYGOUS EFFECTS OF IRRADIATED CHROMOSOMES ON VIABILITY IN DROSOPHILA MELANOGASTER
Authors: Simmons Michael J 
Published: April 2021

ABSTRACT
Two large experiments were conducted in order to evaluate the heterozygous effects of irradiated chromosomes on viability. Mutations were accumulated on several hundred second chromosomes by delivering doses of 2,500r over either two or four generations for total X-ray exposures of 5,000r or 10,000r. Chromosomes treated with 5,000r were screened for lethals after the first treatment, and surviving nonlethals were used to generate families of fully treated chromosomes. The members of these families shared the effects of the first irradiation, but differed with respect to those of the second. The chromosomes treated with 10,000r were not grouped into families since mutations were accumulated independently on each chromosome in that experiment. Heterozygous effects on viability of the irradiated chromosomes were tested in both isogenic (homozygous) and nonisogenic (heterozygous) genetic backgrounds. In conjunction with these tests, homozygous viabilities were determined by the marked-inversion technique. This permitted a separation of the irradiated chromosomes into those which were drastic when made homozygous and those which were not. The results indicate that drastic chromosomes have deleterious effects in heterozygous condition, since viability was reduced by 2-4% in tests performed with the 10,000r chromosomes, and by 1% in those involving the 5,000r material. Within a series of tests, the effects were more pronounced when the genetic background was homozygous. Nondrastic irradiated chromosomes did not show detectable heterozygous effects. They also showed no homozygous effects when compared to a sample of untreated controls. In addition, there was no evidence for an induced genetic component of variance with respect to viability in these chromosomes. These results suggest that the mutants induced by high doses of X-rays are principally drastic ones which show deleterious effects on viability in heterozygous condition.
HIDDEN GENETIC VARIABILITY WITHIN ELECTROMORPHS IN FINITE POPULATIONS
Authors: Chakraborty Ranajit , Nei Masatoshi 
Published: April 2021

ABSTRACT
The amount of hidden genetic variability within electromorphs in finite populations is studied by using the infinite site model and stepwise mutation model simultaneously. A formula is developed for the bivariate probability generating function for the number of codon differences and the number of electromorph state differences between two randomly chosen cistrons. Using this formula, the distribution as well as the mean and variance of the number of codon differences between two identical or nonidentical electromorphs are studied. The distribution of the number of codon differences between two randomly chosen identical electromorphs is similar to the geometric distribution but more leptokurtic. Studies are also made on the number of codon differences between two electromorphs chosen at random one from each of two populations which have been separated for an arbitrary number of generations. It is shown that the amount of hidden genetic variability is very large if the product of effective population size and mutation rate is large.
THE FREQUENCY AND ALLELISM OF LETHAL CHROMOSOMES IN ISOLATED DESERT POPULATIONS OF DROSOPHILA PSEUDOOBSCURA
Authors: Bryant Stephen H 
Published: April 2021

ABSTRACT
Second-chromosome lethals were extracted from four populations of Drosophila pseudoobscura in Southern California. Two of the populations were from desert oases and two from the classic habitat on Mt. San Jacinto, previously studied by Dobzhansky. Allelism tests were made on the lethals within and between all locations. The frequency of lethal second-chromosomes in each location was 0.18, and this was not different from the results of other workers for samples throughout the species range. Interpopulational allelism rates were about 0.005, and not different from earlier results of Dobzhansky. Intrapopulational rates in this study were, with one exception, the same as the interpopulational rates, and significantly lower than Dobzhansky found using the third chromosome. This may be due to lethals being linked with heterotic third-chromosome inversions. The allelism rate of the exceptional population (about 0.03 and equal to Dobzhansky's intrapopulational results) may be due to heterotic lethals, or a founder effect. Two lethals were found in three populations each, possibly due to migration among these populations, which are up to 334 km apart.
GENE DIFFERENCES BETWEEN THIRD-CHROMOSOME INVERSIONS OF DROSOPHILA PSEUDOOBSCURA
Authors: Prakash Satya 
Published: April 2021

ABSTRACT
Associations of alleles of the acid phosphatase-3 locus with the different third-chromosome inversions from different populations of D. pseudoobscura are described. We observe only the allele AP-31.0 in the Standard and Arrow-head inversions and the allele AP-3.98 in the Santa Cruz, Treeline, Cuernavaca and the Pikes Peak arrangements. The Chiricahua gene arrangement is polymorphic.
THE NATURE OF QUANTITATIVE GENETIC VARIATION IN DROSOPHILA. III. MECHANISM OF DOSAGE COMPENSATION FOR SEX-LINKED ABDOMINAL BRISTLE POLYGENES
Authors: Frankham R 
Published: April 2021

ABSTRACT
Seventeen lines, each homozygous for a different × chromosome but all with a common autosomal genetic background, were constructed and assayed for abdominal bristle number to determine whether dosage compensation operates for sex-linked genes affecting this character.—The regression coefficient of male mean on female mean using a logarithmic scale was 0.90 ± 0.13 and the genetic regression coefficient 0.92, neither differing significantly from unity. The genetic components of variance in males and females were also very similar (0.000234 or 0.000228, respectively). These results indicate that dosage compensation is complete (or nearly so) for sex-linked genes affecting this character. The bristle scores of females did not differ in reciprocal crosses between these lines, thus dosage compensation does not operate by paternal × inactivation.—The question of an adequate scale for abdominal bristle number had to be examined during the study. A logarithmic scale appeared to be adequate for both genotypic and environmental differences.
PROTEINASE MUTANTS OF SACCHAROMYCES CEREVISIAE
Authors: Jones Elizabeth W 
Published: April 2021

ABSTRACT
Fifty-nine mutants with reduced ability to cleave the chymotrypsin substrate N-acetyl-DL-phenylalanine β-naphthyl ester have been isolated in S. cerevisiae. All have reduced levels of one or more of the three well-characterized proteinases in yeast. All have reduced levels of proteinase C (carboxy-peptidase Y). These mutations define 16 complementation groups.
CHROMOSOMAL POLYMORPHISMS OF CONSTITUTIVE HETEROCHROMATIN AND INVERSIONS IN DROSOPHILA
Authors: Baimai Visut 
Published: April 2021

ABSTRACT
A simple technique for preparing mitotic metaphases from a larval ganglion of Drosophila is described. Parallel examination of polytene and metaphase chromosome groups shows that inversion polymorphism in chromosome 3 of D. recticilia from East Maui (Hawaii) manifests a one-to-one correlation with a metaphase karyotype polymorphism due to the presence of an extra heterochromatic portion. These observations are consistent with the previous findings on other species of Hawaiian Drosophila. They strongly support the hypothesis that when one breakpoint of a long inverted segment of a chromosome element occurs in the vicinity of the constitutive heterochromatin, it may exert an effect in eliciting the production of heterochromatic material in the same chromosome.
VARIANCE OF GENE FREQUENCIES FROM RECURRENT SELECTION IN FINITE POPULATIONS
Authors: Park Young Chul 
Published: April 2021

ABSTRACT
An equation was derived for estimation of the variance of gene frequencies due to drift in the presence of recurrent selection. The equation assumes knowledge of gene frequencies in successive generations. These can be approximated in at least three ways. Simulation data demonstrated that when satisfactory approximations are used, the variances supplied by the derived formula agree well with observed variances.
INBREEDING ESTIMATION FROM POPULATION DATA: MODELS, PROCEDURES AND IMPLICATIONS
Authors: Spielman Richard S , Neel James V , Li Francis H F 
Published: April 2021

ABSTRACT
Four different estimation procedures for models of population structure are compared. The parameters of the models are shown to be equivalent and, in most cases, easily expressed in terms of the parameters Wright calls "F-statistics." We have estimated the parameters of each of these models with data on nine codominant allele pairs in 47 Yanomama villages, and we find that the different estimators for a given parameter all yield more or less equivalent results.
F-statistics are often equated to inbreeding coefficients that are defined as the probability of identity by descent from alleles taken to be unique in some founding population. However, we are led to infer from computer simulation and general historical considerations that all estimates from genotype frequencies greatly underestimate the inbreeding coefficient for alleles in the founding population of American Indians in the western hemisphere. We surmise that in the highly subdivided tribal populations which prevailed until the recent advent of civilization, the probability of identity by descent for homologous alleles was roughly 0.5. We consider some consequences of working with the customary, much lower, estimates—0.005 to 0.01—if, on the time scale of human evolution, these represent only a very recent departure from the inbreeding intensity that prevailed before civilization.
A CYTOGENETIC ANALYSIS OF CYCLIC NUCLEOTIDE PHOSPHODIESTERASE ACTIVITIES IN DROSOPHILA
Authors: Kiger John A , Golanty Eric 
Published: April 2021

ABSTRACT
The genome of Drosophila melanogaster has been surveyed for chromosomal regions which exert a dosage effect on the activities of cAMP phosphodiesterase or cGMP phosphodiesterase. Two regions increase cAMP phosphodiesterase activity when present as duplications. A region of the X chromosome increases cAMP phosphodiesterase activity when duplicated and decreases that activity when deficient. This region has been delimited to chromomeres 3D3 and 3D4, with 3D4 being the most probable locus, and may contain a structural gene for cAMP phosphodiesterase. A region on the third chromosome, 90E-91B, increase cAMP phosphodiesterase activity when duplicated but has no affect on the activity when deficient. Two regions increase cGMP phosphodiesterase activity when present as duplications. A region of the X chromosome, 5D-9C, increases cGMP phosphodiesterase activity when duplicated, but smaller duplications covering this region fail to show such an increase, indicating that a single locus is not responsible for the increase observed for the larger duplication. A region of the third chromosome, 88C-91B, also increases cGMP phosphodiesterase activity when duplicated. Smaller duplications covering this region show smaller increases than that observed for the larger duplication, suggesting that at least three loci between 88C and 91B contribute to the observed increase by that region. Deficiencies covering region 88C-91B do not affect cGMP phosphodiesterase activity. No locus for a presumptive structural gene for cGMP phosphodiesterase has been found. Limitations of the use of segmental aneuploidy in locating structural genes for enzymes are discussed.
CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. I. THE X CHROMOSOME AND EGG PRODUCTION
Authors: Chapco William 
Published: April 2021

ABSTRACT
Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg production. By making a series of crosses among original and derived recombinant lines, it was possible to estimate parameters representing additive, dominance and interaction effects of the segments. It was shown that whereas most of the segments were additive for egg production when homozygous, they all displayed dominance in the heterozygous condition. Two of the strains were characterized by intersegmental interaction. A possible position effect was detected for these same two strains, with flies in the coupling phase laying more eggs than those in the repulsion configuration. There was no apparent relationship between the number of eggs laid and the amount of heterozygosity within the X chromosome.
MATERNAL INHERITANCE OF ENZYMES IN THE MEALYBUG PSEUDOCOCCUS OBSCURUS (HOMOPTERA)
Authors: Nur Uzi 
Published: April 2021

ABSTRACT
In the mealybug Pseudococcus obscurus Essig (Pseudococcidae) two esterases, a tyrosinase and a mannosephosphate isomerase, exhibited an unusual type of maternal inheritance. Electromorphs (alleles) were transmitted by both parents but segregation was delayed by one generation and full sisters always had the same phenotype. Moreover, for esterase-1, in which three alleles were present, some of the females exhibited all three alleles. Several other polymorphic loci exhibited normal transmission and segregation. This mode of inheritance can be readily explained by assuming that most or all of the enzymes coded for by these loci are produced by the mycetocytes. The mycetocytes house intracellular bacteria-like symbionts and are usually formed by the fusion of the polar bodies and one or more cleavage nuclei. For a locus with two alleles exhibiting this type of inheritance, the expected frequencies of the three phenotypes are p 3, 3pq and q 3. An equation is presented for estimating the frequency of alleles from the frequencies of the phenotypes and it is shown that for three samples from wild populations there is a good agreement between the expected and observed frequencies of the phenotypes.
MULTIPLE INTERACTIONS OF A DNA-BINDING PROTEIN IN VIVO. III. PHAGE T4 GENE-32 MUTATIONS DIFFERENTIALLY AFFECT INSERTION-TYPE RECOMBINATION AND MEMBRANE PROPERTIES
Authors: Mosig Gisela , Berquist William , Bock Susan 
Published: April 2021

ABSTRACT
We have investigated the in vivo roles of T4 gene-32 protein in recombination. We have studied the effects of gene-32 mutations under conditions that allow normal DNA replication and are permissive for progeny production. Under these conditions, certain gene- 32 mutations specifically reduce insertion-type (short-interval) recombination but none affect crossover-type (long-interval) recombination (see Figure 5). Heterozygote frequencies in all gene-32 mutants are similar to or higher than in a gene-32 + background and are not correlated with recombination deficiencies. "Recombination-deficient" alleles are dominant or codominant over the "recombination-proficient" gene-32 mutation tsL171. This explains apparent discrepancies between a gene-32 map deduced from two-factor crosses and the map derived from three-factor crosses.
We have also found that the "recombination proficient" mutation tsL171 and its homoalleles suppress the characteristic plaque morphology of rll mutants. Under restrictive conditions, tsL171 is partially suppressed by rll mutations, which allow the use of host ligase in recombination.
Our present and previous results are discussed in terms of current recombination models. We conclude that gene-32 protein functions in recombination by forming a complex with DNA, with recombination enzymes and with membrane components. Since gene-32 protein interacts with many components of this recombination complex, gene-32 mutations may differentially affect various recombination steps.
INHERITANCE OF THE 2μm DNA PLASMID FROM SACCHAROMYCES
Authors: Livingston Dennis M 
Published: April 2021

ABSTRACT
A variety of Saccharomyces strains were examined for the presence of 2µ DNA and, if present, for the pattern of fragments produced by its digestion with site-specific (restriction) endonucleases. Two strains were found that did not contain detectable levels of 2µ DNA, and two strains contained 2µ DNA molecules having only one EcoRI restriction endonuclease recognition site rather than the usual two.—A haploid containing 2µ DNA with one EcoRI restriction site was mated with a haploid containing 2µ DNA with two EcoRI restriction sites and the resulting diploid maintained both types during vegetative growth. Sporulation of the diploid produced four spores, and the clones from these spores contained both types.—A haploid lacking 2µ DNA was mated with a haploid containing 2µ DNA and the resulting diploid contained 2µ DNA. The four clones derived from the haploid spores after sporulation of this diploid all contained 2µ DNA. A rho - strain without 2µ DNA was mated to a rho + strain with 2µ DNA, and heteroplasmons were selected that had received the nucleus from the strain without 2µ DNA and the mitochondria from the strain with 2µ DNA. Twelve of twenty-four such clones contained 2µ DNA.—I conclude that: (1) the different types of 2µ DNA identified in these strains do not restrict one another, (2) the different types are inherited extrachromosomally, (3) lack of 2µ DNA in two strains is not due to the absence of genes needed for maintenance and (4) the approximately 100 copies of 2µ DNA contained within a single cell are probably clustered within one or a few cytoplasmic organelles.
EVIDENCE FOR DUPLICATION AND DIVERGENCE OF THE STRUCTURAL GENE FOR PHOSPHOGLUCOISOMERASE IN DIPLOID SPECIES OF CLARKIA
Authors: Gottlieb L D 
Published: April 2021

ABSTRACT
Formal genetic analysis of the mode of inheritance of the electrophoretic phenotypes for phosphoglucoisomerase (PGI) in the annual plants Clarkia rubicunda and C. xantiana showed that these diploid species have two and three genes, respectively, that specify PGI subunits. Electrophoretic examination of seven other diploid species of Clarkia revealed that species assigned to ancestral sections in the current taxonomy have two PGI genes, whereas more specialized species have three PGI genes. Together with evidence that diploid species in two closely related genera have two PGI genes, this suggests the third PGI gene arose within Clarkia. Intergenic heterodimers are formed between polypeptides specified by the third gene and one of the other PGI genes, indicating they have a high degree of structural similarity. The combined genetic, biochemical, and phylogenetic evidence suggests that the third PGI gene resulted from a process of gene duplication. The apparent Michaelis constants (F6P to G6P) of the most common electrophoretic variants of the ancestral gene in C. xantiana and in C. rubicunda are closely similar, but that of the duplicate enzyme is much higher. The intergenic heteromer has an intermediate value. Four alleles have been identified for the duplicate PGI gene in C. xantiana, including a null allele which eliminates the activity of its product. This allele is one of the few examples of a "silenced" duplicate gene. The ancestral and duplicate genes assort independently in C. xantiana. In conjunction with the substantial chromosomal rearrangements that characterize species of Clarkia, this may mean that the duplicate PGI marks a duplicated chromosomal segment that originated from a cross between partially overlapping reciprocal translocations rather than from unequal crossing over.
NUCLEOLUS ORGANIZERS IN MUS MUSCULUS SUBSPECIES AND IN THE RAG MOUSE CELL LINE
Authors: Dev V G , Tantravahi R , Miller D A , Miller O J 
Published: April 2021

ABSTRACT
Silver staining has been used to detect active nucleolus organizer regions (NOR's). By this criterion six mouse chromosomes, numbers 12, 15, 16, 17, 18 and 19, can have an NOR. The number and distribution of chromosomes with NOR's vary among inbred strains of Mus musculus musculus (C57BL/6J, BALB/cJ, C3H/HeJ and C3H/StCr1BR) and in M. musculus molossinus. In a musculus x molossinus F1 hybrid, nucleolus organizers from each parent are silver stained.—Chromosomes which have NOR's in diploid cells also show them in tetraploid cells and in established cell lines. The BALB/cJ strain shows Ag-staining of NOR's on chromosomes 12, 15, 18 and occasionally 16. In the RAG cell line, which was derived from BALB/c, active NOR's are seen on 12, 15 and 18, even after these chromosomes have undergone structural rearrangements in the cell line. Some correlation exists between the amount of Ag-stain and the size of a secondary construction region, with a large amount of Ag-stain present on a chromosome which has a prominent secondary constriction. There is no correlation between the amount of Ag-stain and the presence or absence of C-band material.
THE EFFECTS OF GENOTYPIC FREQUENCY AND POPULATION DENSITY ON FITNESS DIFFERENTIALS IN ESCHERICHIA COLI
Authors: Smouse Peter , Kosuda Kazuhiko 
Published: April 2021

ABSTRACT
Two strains of Escherichia coli K-12, a lac + wild type and a lac - auxotroph, were grown both as pure and mixed cultures, using a serial transfer procedure. Four different growth media were employed, consisting of the same minimal salts solution, but different total concentrations of the sugars lactose, arabinose, and glucose (in proportions 5:4:1). Population densities and genotypic frequencies were assayed every 48 hours, at the time of transfer. Population density of the pure lac + culture was greater than that of the pure lac - culture for all media; this was expected, since the latter cannot utilize lactose. Mixed cultures quickly approached the same density as the corresponding lac + controls, and the frequency of the lac + genotype increased steadily for all media. Trajectories of Λ = log (P ÷ Q) were strictly nonlinear, indicating a dependence of the selective differential on population density and genotypic frequency. The rate of substitution decreased slightly with increasing sugar concentration, contrary to theoretical expectation. It was speculated that either the generation interval was longer for denser cultures (higher substrate concentrations) or that buildup of organic by-products reduced the selective differential in denser cultures. For a single medium, however, the behavior of competing genotypic strains was reasonably well predicted by theoretical models of frequency and density-dependent selection, the parameters of which may be related to the experimental inputs.