bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENOTYPES SUPPRESSING MEIOTIC DRIVE OF A B CHROMOSOME IN THE MEALYBUG, PSEUDOCOCCUS OBSCURUS
Authors: Nur Uzi , Brett Betty Lou H 
Published: January 2021

ABSTRACT
The rate of transmission (k) of a supernumerary B chromosome in male mealybugs is shown to depend strongly on the chromosome set of maternal origin. When both parents came from an isofemale line in which the frequency of the B chromosome increased rapidly and stabilized at a mean of more than 4.0 B chromosomes per individual, k was 0.92 and 0.95 in two series of crosses. However, when the female parent came from one of two isofemale lines in which the frequency of the B chromosome decreased from 2.0 to 0 in a few generations, k ranged from 0.53 to 0.78. The high ks, which represent a strong meiotic drive, are apparently responsible for the observed increase in the frequency of the B chromosome in several lines from a mean of about 0.5 to more than 4.0 in about 20 generations. The rapid loss of the B chromosome in other lines is attributed to genetic factors which caused the reduction in the rate of transmission of the B chromosome.
PHYSIOLOGICAL CHARACTERIZATION OF ADAPTIVE CLONES IN EVOLVING POPULATIONS OF THE YEAST, SACCHAROMYCES CEREVISIAE
Authors: Adams Julian , Paquin Charlotte , Oeller Paul W , Lee Lester W 
Published: January 2021

ABSTRACT
Populations of a diploid strain of S. cerevisiae were grown in glucose-limited continuous culture for more than 260 generations. A series of seven sequential adaptive changes were identified by monitoring the frequency of cycloheximide resistance in these populations. Samples were taken from the continuous cultures following each adaptive shift and characterized physiologically to determine (1) the range of phenotypes that can be selected in a precisely defined constant environment and (2) the order and predictability of the occurrence of the adaptive mutations in evolving populations. The clones were characterized with respect to the growth parameters, maximum growth rate, saturation coefficient and yield, as well as for changes in cell size and geometry and rate of glucose uptake. The maximum growth rates of the seven adaptive clones were very similar, but in contrast the saturation coefficients differed substantially. Surprisingly, not all clones showed reductions in the saturation coefficients, in comparison to the immediately preceding clones, as would be predicted from classical continuous culture kinetics. In addition, yield estimates first increased and then decreased for later isolated adaptive clones. In general, the results suggest epistatic interactions between the adaptive clones, consistent with earlier published results. The rate of glucose uptake, as measured by 14Cxylose uptake, increased dramatically after the selection and fixation of seven adaptive clones. Progressive decreases in cell volume and changes in cell geometry, resulting in increased surface area to volume ratios, were also observed in the adaptive clones, but these changes were not always seen in other haploid and diploid yeast populations evolving under the same conditions. Such changes may be easily explainable in terms of the characteristics of the glucose-limited environment. The significance of the results to the evolution of microorganisms under nutrient-limiting conditions is discussed.
THE AFFECTED SIB METHOD. I. STATISTICAL FEATURES OF THE AFFECTED SIB-PAIR METHOD
Authors: Motro Uzi , Thomson Glenys 
Published: January 2021

ABSTRACT
The distribution of the number of HLA haplotypes shared by sibs affected with the same HLA-linked disease can be used to obtain information on the genetics of the disease. Since the inception of the use of sib-pair methods for the analysis of the HLA-associated diseases, the question has been raised of how to include families with more than two affected sibs in the sib-pair analysis. This paper presents appropriate weighting schemes. A procedure for estimating the frequency of the disease allele in the general population, under the assumptions of single-allele recessive, additive, dominant and intermediate models, with negligible recombination (θ = 0) between the disease-predisposing gene and the HLA region, and no selective disadvantage of the trait, is also given. Cluster-sampling techniques are used in the analysis.
GENETIC ANALYSIS OF STAPHYLOCOCCAL NUCLEASE: IDENTIFICATION OF THREE INTRAGENIC "GLOBAL" SUPPRESSORS OF NUCLEASE-MINUS MUTATIONS
Authors: Shortle David , Lin Beth 
Published: January 2021

ABSTRACT
A collection of 77 unique missense mutations distributed across the gene encoding staphylococcal nuclease (nuc) has been assembled. These mutations were induced by random gap misrepair mutagenesis of the cloned gene and were identified in E. coli transformants expressing reduced levels of nuclease activity. Four nuc - mutations which alter amino acid residues at positions outside of the active site region of the enzyme were submitted to a second round of mutagenesis, and characterization of several independent NUC+ isolates lead to the identification of three second-site suppressor mutations within the protein-coding sequence of the nuc gene. On separation from the mutation originally suppressed and recombination with a number of other nuc - mutations, all three suppressors displayed the property of "global" suppression, i.e., phenotypic suppression of the nuclease-minus character of multiple different alleles. A simple and generally applicable strategy was used to obtain efficient homologous recombination between plasmids for purposes of mapping nuc - mutations, mapping second-site suppressors and constructing double mutant combinations from pairs of single mutations.
LOCALIZED CONVERSION IN STREPTOCOCCUS PNEUMONIAE RECOMBINATION: HETERODUPLEX PREFERENCE
Authors: Sicard Michel , Lefevre Jean-Claude , Mostachfi Pezechpour , Gasc Anne-Marie , Sarda Claudine 
Published: January 2021

ABSTRACT
In pneumococcal transformation the frequency of recombinants between point mutations is generally proportional to distance. We have recently described an aberrant marker in the amiA locus that appeared to enhance recombination frequency when crossed with any other allele of this gene. The hyperrecombination that we have observed in two-point crosses could be explained by two hypotheses: the aberrant marker induces frequent crossovers in its vicinity or the mutant is converted to wild type. In this report we present evidence showing that, in suitable three-point crosses, this hyperrecombination does not modify the recombination frequency between outside markers, suggesting that a conversion occurs at the site of this mutation. To estimate the length over which this event occurs, we isolated very closely linked markers and used them in two-point crosses. It appears that the conversion system removes only a few base pairs (from three to 27) around the aberrant marker. This conversion process is quite different from the mismatch-repair system controlled by hex genes in pneumococcus, which involves several thousand base pairs. Moreover, we have constructed artificial heteroduplexes using separated DNA strands. It appears that only one of the two heteroduplexes is specifically converted. The conversion system acts upon 5′..ATTAAT..3′/3′..TAAGTA..5′. A possible role of the palindrome resulting from the mutation is discussed.
STATISTICAL PROPERTIES OF THE NUMBER OF RECOMBINATION EVENTS IN THE HISTORY OF A SAMPLE OF DNA SEQUENCES
Authors: Hudson Richard R , Kaplan Norman L 
Published: January 2021

ABSTRACT
Some statistical properties of samples of DNA sequences are studied under an infinite-site neutral model with recombination. The two quantities of interest are R, the number of recombination events in the history of a sample of sequences, and RM, the number of recombination events that can be parsimoniously inferred from a sample of sequences. Formulas are derived for the mean and variance of R. In contrast to R, RM can be determined from the sample. Since no formulas are known for the mean and variance of RM, they are estimated with Monte Carlo simulations. It is found that RM is often much less than R, therefore, the number of recombination events may be greatly under-estimated in a parsimonious reconstruction of the history of a sample. The statistic RM can be used to estimate the product of the recombination rate and the population size or, if the recombination rate is known, to estimate the population size. To illustrate this, DNA sequences from the Adh region of Drosophila melanogaster are used to estimate the effective population size of this species.
A NEW METHOD FOR THE SCREENING OF MUTATIONS RELATED TO PROTOPLASMIC INCOMPATIBILITY, DIFFERENTIATION AND PLASMA MEMBRANE IN THE FUNGUS PODOSPORA ANSERINA
Authors: Labarère Jacques , Bonneu Marc 
Published: January 2021

ABSTRACT
In Podospora anserina previous investigations showed that mutations in genes involved in the control of protoplasmic incompatibility cause defects at various stages of differentiation during the life cycle and also modify properties of the plasma membrane. To establish these relationships in another way, a new method for screening mutations has been developed as a first step. Eighty-five new mutants were selected for resistance to toxic products (sorbose or thiourea); in a second step these mutants were tested for modifications of protoplasmic incompatibility and cellular differentiation. Seven of the sorbose or thiourea resistant-mutants (i.e., 8%) exhibited new patterns of protoplasmic incompatibility. Genetic analyses were carried out with three mutants. Mutation X25 suppresses protoplasmic incompatibility resulting from all allelic interactions and restores the fertility of the crosses ♀ V × ♂ V1 and ♀ Z1 × ♂ Z2. Mutation V41 is an allele of the v locus with new properties. Mutation X61 totally suppresses the V/V'1 interaction and weakens all of the other allelic incompatibility systems; X61 strains are defective in protoperithecia differentiation. Electrophoresis of plasma membrane proteins showed that X61 strains lack two polypeptides whose apparent molecular weights are 41,000 and 44,000. This new screening method is especially efficient for obtaining new mutants and identifying additional genes involved in incompatibility. These results provide further support demonstrating the relationships between protoplasmic incompatibility, cellular differentiation and plasma membrane.
SUM1, AN APPARENT POSITIVE REGULATOR OF THE CRYPTIC MATING-TYPE LOCI IN SACCHAROMYCES CEREVISIAE
Authors: Klar Amar J S , Kakar Satya N , Ivy John M , Hicks James B , Livi George P , Miglio Lisa M 
Published: January 2021

ABSTRACT
The mating-type information residing at the HML and HMR loci in Saccharomyces cerevisiae is kept unexpressed by the action of at least four MAR (or SIR) loci. To determine possible interactions between the MAR/SIR gene products and to find new regulatory loci, we sought extragenic suppressors of the mar1-1 mutation. A strain with the genotype HML a MATα HMR a mar1-1 is unable to mate because of the simultaneous expression of a and α information. A mutant of this strain was isolated that exhibits an α phenotype and, therefore, presumably fails to express the HML and HMR loci. We designate the new locus SUM1(supressor of mar). The mutation is recessive, centromere unlinked and does not correspond to the MAT, HML, HMR, SIR1, MAR1, MAR2(SIR3) or SIR4 loci. The sum1 mutation affects expression of both a and α information at the HM loci. Suppression by sum1-1 is neither allele specific nor locus specific as it suppresses a deletion mutation of the MAR1 locus and mutations in SIR3 and SIR4. The sum1-1 mutation has no discernible phenotype in a Mar+ strain. We propose that the MAR/SIR gene produts negatively regulate the SUM1 locus, the gene product of which is necessary for expression of the HM loci.
THE ALLELIC CORRELATION STRUCTURE OF GAINJ-AND KALAM-SPEAKING PEOPLE. I. THE ESTIMATION AND INTERPRETATION OF WRIGHT'S F-STATISTICS
Authors: Long Jeffrey C 
Published: January 2021

ABSTRACT
The internal patterning of allelic correlations in the Gainj and Kalam swidden horticulturalists of highland Papua New Guinea is examined within the context of Sewall Wright's F-statistic model. A multiallelic extension of the model is given first, and multivariate variance-component estimators for the parameters are suggested. Then, it is shown that the expectation of the F-statistic set depends on the age structure of the population and that knowledge of the population and sample age structure is critical for meaningful analysis. The array of F-statistics estimated jointly over five polymorphic enzyme loci reveals the following features of Gainj and Kalam population structure: (1) significant departures from panmictic expectations and (2) characteristics of a continuously distributed breeding population, rather than those expected for populations subdivided into demes with discrete boundaries. Finally, the F-statistics estimated for the Gainj and Kalam are briefly compared to estimates obtained from other tribal populations. It is seen that the level of differentiation observed in the Gainj and Kalam is only about one-third that observed in South American swidden horticulturalists. Consequently, some conventional wisdom regarding the interrelationship of socioecological settings and genetic structures may require reevaluation.
INTERCHROMOSOMAL BIASED GENE CONVERSION, MUTATION AND SELECTION IN A MULTIGENE FAMILY
Authors: Slatkin Montgomery 
Published: January 2021

ABSTRACT
A mathematical model of the effects of interchromosomal biased gene conversion, mutation and natural selection on a multigene family is developed and analyzed. The model assumes two allelic states at each of n loci. The effects of genetic drift are ignored. The model is developed under the assumption of no recombination, but the analysis shows that, at equilibrium, there is no linkage disequilibrium, which implies that the conclusions are valid for arbitrary recombination among loci. At equilibrium, the balance between mutation, gene conversion and selection depends on the ratio of the mutation rates to the quantity [s + g(2α - 1)/n], where s is the increment or decrement in relative fitness with each additional copy of one of the alleles, g is the conversion rate, and α is a measure of the bias in favor of one of the alleles. When this quantity is large relative to the mutation rates, the allele that has the net advantage, combining the effects of selection and conversion, will be nearly fixed in the multigene family. A comparison of these results with those from a comparable model of intrachromosomal biased conversion shows that biased interchromosomal conversion leads to approximately the same equilibrium copy number as does intrachromosomal conversion of the same strength. Interchromosomal conversion is much more effective in causing the substitution of one allele by another. The relative frequencies of interchromosomal and intrachromosomal conversion is indicated by the extent of the linkage disequilibrium among the loci in a multigene family.
A DIPHENOL OXIDASE GENE IS PART OF A CLUSTER OF GENES INVOLVED IN CATECHOLAMINE METABOLISM AND SCLEROTIZATION IN DROSOPHILA. I. IDENTIFICATION OF THE BIOCHEMICAL DEFECT IN Dox-A2 [l(2)37Bf] MUTANTS
Authors: Pentz Ellen Steward , Black Bruce C , Wright Theodore R F 
Published: January 2021

ABSTRACT
Phenol oxidase, a complex enzyme, plays a major role in the processes of sclerotization and melanization of cuticle in insects. Several loci have been reported to affect levels of phenol oxidase activity, but to date only one structural locus has been identified [Dox-3F (2-53.1+)]. Recently isolated Dox-A2 mutations (2-53.9) are recessive, early larval lethals, which as heterozygotes reduce phenol oxidase activity. A homozygous mutant escaper had weak, completely unpigmented cuticle and unpigmented bristles. Enzyme assays show that Dox-A2 heterozygotes have diphenol oxidase activity reduced to 47-79% of wild type, whereas monophenol oxidase activity, at 94-106% of wild type, is normal. Elevated pool sizes of the diphenol oxidase substrates DOPA, dopamine, and N-acetyldopamine are observed in the mutant, confirming the enzyme assay results. Separation of the three phenol oxidase A component activities on polyacrylamide gels shows that Dox-A2 mutations reduce the activity of only the A2 component. Dox-A2 may identify a structural locus for the A2 component of the diphenol oxidase enzyme system.—The Dox-A2 locus is one of 18 loci in the dopa decarboxylase, Df(2L)TW130 region of the second chromosome, at least 14 of which affect the formation, melanization or sclerotization of cuticle in some way. These loci form an apparent cluster of functionally related genes.
HETEROSIS AT ALLOZYME LOCI UNDER INBREEDING AND CROSSBREEDING IN PINUS ATTENUATA
Authors: Strauss Steven H 
Published: January 2021

ABSTRACT
The dependence of heterosis at isozyme loci on inbreeding and crossbreeding was studied in 10-yr-old trees of knobcone pine (Pinus attenuata Lemm.). Heterozygosity was determined at 24 polymorphic isozyme loci and related to the rate of vegetative growth and cone production. The inbreds, created by selfpollination, had 46% of the heterozygosity of their mothers; the crossbreds, created by interpopulation crossing, had 155% of the heterozygosity of their mothers. Within the crossbreds, heterozygosity was positively correlated with trunk growth, but negatively correlated with cone production. Results in the crossbreds, however, were strongly influenced by a few individuals that showed unusually slow growth, high reproduction and low heterozygosity. Without those individuals, there was no relationship of heterozygosity to either growth or reproduction.—Within the inbreds, heterozygosity was positively correlated with both trunk growth and cone production. Each locus that was heterozygous in the mothers was calculated to mark about 3% of the genome for identity by descent in the inbred progeny; the total proportion of the genome marked was between 10 and 11%. Using these estimates to relate heterozygosity to the inbreeding coefficient (F) gave estimates of inbreeding depression per unit of F that fell within the range of published values for conifers. The strength of heterosis found among the inbreds suggests that single-locus or multilocus overdominance should be exceedingly difficult to detect in natural populations of predominantly outcrossing species
QUANTITATIVE ANALYSIS OF X CHROMOSOME EFFECTS ON THE ACTIVITIES OF THE GLUCOSE 6-PHOSPHATE AND 6-PHOSPHOGLUCONATE DEHYDROGENASES OF DROSOPHILA MELANOGASTER
Authors: Miyashita Naohiko , Laurie-Ahlberg Cathy C , Wilton Alan N , Emigh Ted H 
Published: January 2021

ABSTRACT
By combining 20 X chromosomes with five autosomal backgrounds, the relative importance of these factors with respect to the activity variations of G6PD and 6PGD in Drosophila melanogaster were investigated. Analysis of variance revealed that there exist significant X chromosome, autosomal background and genetic interaction effects. The effect of the X chromosome was due mainly to the two allozymic forms of each enzyme, but some within-allozyme effects were also detected. From the estimated variance components, it was concluded that the variation attributed to the autosomal background is much larger than the variation attributed to the X chromosome, even when the effect of the allozymes is included. The segregation of the allozymes seems to account for about 10% of the total activity variation of each enzyme. The variation due to the interaction between the X chromosome and the autosomal background is much smaller than variations attributed either to the X chromosome or to the autosomal background. The interaction effect is indicated by the change of the ranking of the X chromosomes for different autosomal backgrounds. Highly significant and positive correlation between G6PD and 6PGD activities was detected. Again, the contribution of the autosomal background to the correlation was much larger than that attributed to the X chromosome.
GENETIC DIFFERENCES AMONG THE A/J x C57BL/6J RECOMBINANT INBRED MOUSE LINES AND THEIR DEGREE OF ASSOCIATION WITH GLUCOCORTICOID-INDUCED CLEFT PALATE
Authors: Liu Sharon L , Erickson Robert P 
Published: January 2021

ABSTRACT
Hydrocortisone sodium phosphate was injected intramuscularly into A/J, C57BL/6J and recombinant inbred lines from these two parental lines to study the genetics of steroid-induced cleft palate in a situation of identical maternal and fetal genotypes. The strains were typed for H-2 (the major histocompatibility locus), β-glucuronidase and β2-microglobulin, which served as markers on chromosomes 17, 5 and 2, respectively. Hepatic glucocorticoid binding capacity had been previously measured in Hepes buffer and Hepes buffer plus dithiothreitol (DTT). The level of glucocorticoid binding in Hepes buffer and in Hepes plus DTT, as well as their ratio, was compared to the incidence of steroid-induced cleft palate in the recombinant inbred lines. A correlation was found between the response of glucocorticoid binding to DTT (expressed as a ratio of binding in the presence of DTT to binding without DTT) and hydrocortisone-induced cleft palate. When analyzing the effect of the three chromosomal markers on hydrocortisone-induced cleft palate, the b alleles of β2-microglobulin and of β-glucuronidase were associated with a higher incidence. Genetic analyses of the differences between these two inbred strains of mice in the incidence of steroid-induced cleft palate show it not to be monogenic.
GENETIC FINE STRUCTURE OF THE BRONZE LOCUS IN MAIZE
Authors: Dooner Hugo K 
Published: January 2021

ABSTRACT
The bronze (bz) locus in maize, located in the short arm of chromosome 9 (9S), is the structural gene for the anthocyanin biosynthetic enzyme UFGT. The gene has been cloned and its physical map has been oriented relative to the centromere of 9S. We report here the genetic fine structure mapping of several biochemically characterized EMS-induced bz-E mutations, derived from the Bz-W22 isoallele, and Ds insertion bz-m mutations, derived from the Bz-McC isoallele. Two UFGT-, CRM+ mutants (bz-E2 and bz-E5), which genetically identify coding sequences in the gene, and three UFGT-, CRM- bz-E mutants were mapped against the Ds insertion mutants bz-m1 and bz-m2(DI) by selecting Bz intragenic recombinants from heterozygotes of the type bz-E/bz-m. The exclusive occurrence of one recombinant outside marker class allowed the unambiguous placement of the mutants in a genetic fine structure map. Peculiarly, the two CRM+ bz-E mutants lie upstream of the three CRM- bz-E mutants and at a considerable genetic distance. The UFGT allozymes encoded by the progenitor alleles Bz-W22 and Bz-McC differ in two properties, thermal stability and activity. The sites responsible for these properties were mapped as unselected markers among the Bz intragenic recombinants. The thermal stability site, which also identifies a coding region of the gene, mapped very close to the CRM+ bz-E mutant sites. The site responsible for variation in activity, which probably identifies a region involved in regulation of expression of the bz locus, mapped at the 5' or proximal end of the locus. It was found to be inseparable from the Ds insertion in bz-m1 that lies very close to the 5' end of the transcribed region.—Evidence was obtained that the insertion of Ds within the bz gene has a suppressing effect on intragenic recombination. Additional data are also presented supporting our observation that Ds affects the pattern of intragenic recombination at bz.—Based on the total genetic length of the bz gene and on the physical size of the transcribed region, we estimate that one unit of recombination at bronze corresponds to 14 kb of DNA. This estimate is more than 100 times smaller than the average value for the whole genome and implies that there may be regions, such as bronze, that serve as hotspots for recombination.