bluuebunny/crossref_metadata_2025_split huggingface dataset:
LOCATION AND UNDERREPLICATION OF SATELLITE DNA IN DROSOPHILA MELANOGASTER
Authors: Wollenzien Paul , Barsanti Paolo , Hearst John E 
Published: April 2021

ABSTRACT
The two light nuclear satellites (ρCsCl = 1.672 and ρCsCl = 1.687) have been quantified in DNA isolated from the larvel imaginal discs and brains of Drosophila melanogaster with the genotypes X/O, X/X and X/Y. By comparing the results from these different genotypes, the amounts of the two satellites in the X and Y chromosomes and in the autosomes have been determined. The lightest satellite is not located to any appreciable extent in the X chromosome. The heterochromatic regions are not completely filled by these satellites.—Satellite DNA has also been quantified in DNA isolated from adults containing different genotypes. The two satellites are underreplicated to different extents. The apparent amount of underreplication for one of the satellites is different in different parts of the genome.
GENE FREQUENCY CHANGES AT THE α-AMYLASE LOCUS IN EXPERIMENTAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA
Authors: Yardley Darrell G , Anderson Wyatt W , Schaffer Henry E 
Published: April 2021

ABSTRACT
The frequencies of alleles at the α-Amylase locus of D. pseudoobscura were followed in both large and small experimental populations. No evidence for balancing or directional selection was found, although our ability to detect weak selection is limited. The gene frequency changes in our experimental populations were consistent with the hypothesis of selective neutrality and genetic drift due to sampling error.
DELETION OF MITOCHONDRIAL DNA BYPASSING A CHROMOSOMAL GENE NEEDED FOR MAINTENANCE OF THE KILLER PLASMID OF YEAST
Authors: Wickner Reed B 
Published: April 2021

ABSTRACT
Strains of Saccharomyces cerevisiae carrying a 1.4 × 106 dalton double-stranded (ds) RNA in virus-like particles (the killer plasmid or virus) secrete a toxin that is lethal to strains not carrying this plasmid (virus). The mak10 gene is one of 24 chromosomal genes (called pets, mak1, mak2,…) that are needed to maintain and replicate the killer plasmid. We report here isolation of spontaneous and induced mutants in which the killer plasmid is maintained and replicated in spite of a defect in the mak10 gene. The bypass (or suppressor) mutations in these strains are in the mitochondrial genome. Respiratory deficiency produced by various chromosomal pet mutations, by chloramphenicol, or by antimycin A, does not bypass the mak10-1 mutation. Several spontaneous mak10-1 killer strains have about 12-fold more of the killer plasmid ds RNA than do wild-type killers. Although the absence of mitochondrial DNA bypasses mak10-1, it does not bypass pets-1, mak1-1, mak3-1, mak4-1, mak5-1, mak6-1, mak7-1, or mak8-1.
A COMPARISON OF SURVIVAL AND REPAIR OF UV-INDUCED DNA DAMAGE IN CULTURED INSECT VERSUS MAMMALIAN CELLS
Authors: Koval Thomas M , Hart Ronald W , Myser Willard C , Hink Walter F 
Published: April 2021

ABSTRACT
Survival and unscheduled DNA synthesis (UDS) were measured in a cultured insect cell line, TN-368, and a cultured mammalian cell line, V-79-4, following exposure to several fluences of ultraviolet light. TN-368 cells were approximately seven times more resistant to the lethal effects of UV than V-79 cells, as determined by colony formation. The amount of UDS per unit amount of DNA is about the same in both cell types 4 hr after 10-50 J/m2 UV irradiations.
SPONTANEOUS AND ETHYL METHANESULFONATE-INDUCED MUTATIONS CONTROLLING VIABILITY IN DROSOPHILA MELANOGASTER. II. HOMOZYGOUS EFFECT OF POLYGENIC MUTATIONS
Authors: Ohnishi Ohmi 
Published: April 2021

ABSTRACT
Polygenic mutations affecting viability were accumulated on the second chromosome of Drosophila melanogaster by treating flies with EMS in successive generations. The treated chromosomes were later made homozygous and tested for their effects on viability by comparison of the frequency of such homozygotes with that of other genotypes in the same culture. The treated wild-type chromosomes were kept heterozygous in Pm/+ males by mating individual males in successive generations to Cy/Pm females. The number of generations of accumulation was 1 to 30 generations, depending on the concentration of EMS. A similar experiment for spontaneous polygenic mutations was also conducted by accumulating mutations for 40 generations. The lower limit of the spontaneous mutation rate of viability polygenes is estimated to be 0.06 per second chromosome per generation, which is about 12 times as high as the spontaneous recessive lethal mutation rate, 0.005. EMS-induced polygenic mutations increase linearly with the number of treated generations and with the concentration of EMS. The minimum mutation rate of viability polygenes is about 0.017 per 10-4 m, which is only slightly larger than the lethal rate of 0.013 per 10-4 m. The maximum estimate of the viability reduction of a single mutant is about 6 to 10 percent of the normal viability. The data are consistent with a constant average effect per mutant at all concentrations, but this is about three times as high as that for spontaneous mutants. It is obvious that one can obtain only a lower limit for the mutation rate, since some mutants may have effects so near to zero that they cannot be detected. The possibility of measuring something other than the lower limit is discussed. The ratio of the load due to detrimental mutants to that caused by lethals, the D/L ratio, is about 0.2 to 0.3 for EMS-induced mutants, as compared to about 0.5 for spontaneous mutants. This is to be expected if EMS treatment produces a large fraction of small deletions and other chromosome rearrangements which are more likely to be lethal.
GENETIC ANALYSIS OF MATING-TYPE DIFFERENTIATION IN PARAMECIUM TETRAURELIA
Authors: Brygoo Yves 
Published: April 2021

ABSTRACT
Whereas each of the two complementary mating types, O and E, of Paramecium tetraulrelia normally shows cytoplasmic inheritance, an abnormal heredity of mating type was observed in the progeny of crosses between two stocks of different geographical origin of Paramecium tetraurelia(stock 51 and stock 32). The modified pattern of mating-type inheritance was shown to result from the interaction of the two wild-type alleles at the locus mtD (mtD51 and mtD32), leading to a new differentiated state O*, different from the normal O and E states observed in both stock 51 and stock 32 cells. The genetic analysis of O* clones showed that the O* phenotype involves both a new heritable cytoplasmic state and possibly a nuclear change which can be transmitted through conjugation and segregates in a Mendelian fashion. All the data can be interpreted if the assumption is made that mating-type determination is achieved only by the commitment or noncommitment to the expression of mating-type E, and that this commitment may simply reflect the activation or nonactivation of the locus mtD, under the influence of one or two "cytoplasmic factors" including the product of the gene mtD itself.
THE MEIOTIC EFFECT OF A DEFICIENCY IN DROSOPHILA MELANOGASTER WITH A MODEL FOR THE EFFECTS OF ENZYME DEFICIENCY ON RECOMBINATION
Authors: Robbins Leonard G 
Published: April 2021

ABSTRACT
The meiotic effects of heterozygosity for a deficiency of the zeste-white region of the X chromosome include reduced recombination and increased non-disjunction of the entire chromosome complement. Reduced dosage of a gene or genes in the zeste-white interval, rather than structural heterozygosity, is responsible for the meiotic effect. A model for the recombination effects of reduced enzyme concentration has been developed, and its consequences are comparable with the results obtained for deficiency heterozygosity. Thus, all of the observations can be accounted for by imagining a dosage-sensitive locus in the zeste-white region that codes for an enzyme involved in the recombination process. The interaction of the interchromosomal effect of heterozygous inversions with the deficiency has been examined, and the possibility of using the model for the analysis of other meiotic phenomena is considered.
HETEROSIS AS AN EXPLANATION FOR LARGE AMOUNTS OF GENIC POLYMORPHISM
Authors: Lewontin R C , Ginzburg L R , Tuljapurkar S D 
Published: April 2021

ABSTRACT
By using both numerical and analytical approaches, we have shown that heterosis alone is not a mechanism for maintaining many alleles segregating at a locus. Even when all heterozygotes are more fit than all homozygotes, the proportion of fitness arrays that will lead to a stable, feasible equilibrium of more than 6 or 7 alleles is vanishingly small. More alleles can be maintained if, in addition to heterosis, it is assumed that there is very little variation in fitness from heterozygote to heterozygote, with the ratio of mean heterosis to standard deviation of fitness among heterozygotes in the neighborhood of 10. When such conditions hold, the allelic frequency distribution and equilibrium will be very uniform, with all alleles very close to equal frequency p = - . It is much more likely that stable equilibria for multiple alleles will be best explained by multiple niche selection. 1 n
AFFINITY DISTANCE VALUES AMONG SOMATIC METAPHASE CHROMOSOMES IN MAIZE
Authors: Horn J D , Walden D B 
Published: April 2021

ABSTRACT
In maize root-tip metaphase preparations, all distances between two chromosomes were measured in 50 cells from each of seven stocks and in 30 from one stock; four were arrested with cold, two with 8-hydroxyquinoline, one with colchicine and one with monobromonaphthalene Standardized, affinity-distance values were calculated for all pairs of homologues and pairs of nonhomologues from each preparation. The homologues of pair X were the least separated, those of pair I the most separated in the cold-arrested stocks. All but pairs I and VIII were shown to be significantly different from the observed mean. The observed mean was less than but not significantly different from the theoretical value for a random distribution. The use of chemical agents for metaphase arrest increased the separation of homologues, except for pair I.—Eleven percent of the comparisons of nonhomologues from cold-arrested, as contrasted to none of the comparisons from the c-metaphase treatments, were significantly different from the theoretical talue for a random distribution. This was considered evidence for limited primary nonhomologue association in maize. Although there were specific, differential responses to the two arrest agents, the population of homologous pairs approached a random distribution only in chemically arrested stocks.—Primary homologue association was considered to be maintained by two mechanisms. the more common involving the micro-tubules and the second involving the nucleolus.—Interpretations are offered regarding the claims of somatic association in other species, especially man. The opportunity in maize for experimentally modifying distance values by cytogenetic techniques is discussed.
SPONTANEOUS CHROMOSOME BREAKAGE AT MALE MEIOSIS ASSOCIATED WITH MALE RECOMBINATION IN DROSOPHILA MELANOGASTER
Authors: Henderson S A , Woodruff R C , Thompson J N 
Published: April 2021

ABSTRACT
An inbred line (OKI) of Drosophila melanogaster, recently derived from a natural population in Oklahoma, has been found by WOODRUFF and THOMPSON to exhibit a low frequency of spontaneous male recombination when outcrossed to marker stocks. There is also a reciprocal-cross effect, such that recombination is found only if OK1 males are used in the initial cross. When OK1 females are used, however, male recombinatioii is again found if their male progeny are used for a subsequent cross,-In the present cytological analysis, chromosome behavior at male meiosis was studied in reciprocal crosses between the OK1 line and both a marker gene stock and an inversion stock. If the recombination events were "conventional" and premeiotic (gonial) in origin, no chromosome aberrations would be expected during meiosis. If they were "conventional" and meiotic, some dicentric bridges with free fragments would be expected in the inversion heterozygote, but none should be present in the marker gene cross.—The results demonstrated that the occurrence of recombination in males is most likely a meiotic event, though the occurrence of some limited premeiotic recombination can not be disproven. Meiosis was found to be perfectly normal in all crosses lacking male recombination. In all of the inversion stock and noninversion marker stock crosses that showed male recombination, however, anaphase bridges were found at both first and second meiotic divisions. These were often accompanied by more than the single fragment expected from a conventional inversion bridge and fragment situation. In extreme cases, almost complete pulverization of one or more autosomes was found.—All metaphase I stages were perfectly normal, suggesting that no comparable breakage occurs in premeiotic gonial mitoses. The form of chromosome damage is similar in many ways to that produced by some DNA synthesis inhibitors, or by some viral or mycoplasma infections. This possibility is discussed, and some of the evolutionary implications of the system are briefly considered.
MODES OF SELECTION MAINTAINING AN INVERSION POLYMORPHISM IN DROSOPHILA PAULISTORUM
Authors: Gromko Mark H , Richmond Rollin C 
Published: April 2021

ABSTRACT
The possibility that fitness relationships associated with an inversion polymorphism in D. paulistorum were frequency dependent was investigated. Using allozymes of tetrazolium oxidase to mark inversions, the effects of genotype frequency, larval density, and culture conditions on fitness were assessed. The proportions of genotypes among egg-laying females were varied, thus changing the expected proportions of progeny produced in the absence of fecundity or viability selection. The genotypes of progeny were determined by electrophoresis and comparisons of the ratio of the numbers of the different genotypes produced to the expected ratio was used to evaluate fitness relationships. Fitness relationships were dependent on genotype frequency, larval density, and culture conditions. Selection was either absent, directional, frequency dependent (favoring rare types), or heterotic depending on density and culture conditions. It is implied that the adaptive value of genetic variants need not be apparent in all environments, or may change with changing conditions. There is evidence for different criteria for selection in the two sexes. These results add to the evidence supporting the importance of frequency-dependent selection. It is argued that for frequency dependence to be of general importance, selection must act on genes in groups, either as an inversion or as lengths of chromosome with integrity maintained by disequilibrium.
INFLUENCE OF MATERNAL PHENOTYPE ON METABOLIC DIFFERENTIATION OF AGOUTI LOCUS MUTANTS IN THE MOUSE
Authors: Wolff George L 
Published: April 2021

ABSTRACT
The results of extensive breeding experiments indicate that the phenotypic differentiation of embryos carrying the viable yellow, Avy, or mottled, am, mutations is influenced to a major extent by the agouti locus genotype and the strain genome of the dam. The Avy/a and am/a genotypes are each expressed in a spectrum of coat color phenotypes. These can be grouped into two classes, mottled and pseudoagouti.—In a reciprocal cross of C57BL/6JNIcrWf and AM/Wf-am/am mice, 29.5% of the offspring of C57BL/6 dams were of the pseudoagouti phenotype, whereas no pseudoagouti offspring were produced by AM strain dams.—Mottled yellow Avy/a mice become obese and tumor formation is enhanced in these mice in comparison with the lean pseudoagouti Avy/a siblings.—In two different reciprocal crosses using four different inbred strains, the proportion of pseudoagouti Avy/a offspring differed according to the strain of the dam. Regardless of strain, mottled yellow Avy/a dams produced significantly fewer pseudoagouti Avy/a offspring than did black a/a dams.—The data suggest that metabolic differentiation of Avy/a zygotes into phenotypic classes with different susceptibilities to obesity and tumor formation is influenced to a considerable degree by the metabolic characteristics of the oviductal and uterine environment of the dam.
INHERITANCE OF SEMIDWARFISM IN RICE, ORYZA SATIVA L
Authors: Foster K W , Rutger J N 
Published: April 2021

ABSTRACT
The inheritance of plant height was investigated in a ten-parent diallel cross of diverse rice cultivars. Parents included two tall japonica lines and eight semidwarf lines. Data from parent, F1, F2, and F3 generations indicated that the majority of height variation among the ten parents could be accounted for by three major genes with additive loci effects. D51, 72/2234-11, and G33 (derived from the known major-gene indica semidwarf Dee-geo-woo-gen) all were found to possess an allelic, partially recessive semidwarfing gene (sd1). Additional semidwarfing genes were detected in D66 (sd2, fully recessive) and in CI 9858 (sd3, partially to fully recessive). Relative magnitudes of additive effects were sd1 &gt; sd2 ≥ sd3. Hokuriki 76, Tedoriwase, and IV 29-4 were found to be dwarfed by a multiple-gene system. Hayman-Jinks diallel cross analysis on parent and F1 information (1974 and 1975) and on parent and F2 information demonstrated the presence of significant additive and dominance variation, but epistasis was not detected. A preponderance of dominant alleles with partial dominance for increased plant height was observed. Since diallel statistics reflect properties of genes with larger effects, the genetic model proposed from segregation analysis was in substantial agreement with predictions of the Hayman-Jinks analysis.
ON THE REGULATION OF GENE EXPRESSION: INCOMPATIBILITY IN SCHIZOPHYLLUM
Authors: Ullrich Robert C 
Published: April 2021

ABSTRACT
A new functional class of nucleic acids is postulated on the basis of the multiallelic incompatibility system regulating sexual morphogenesis in the higher fungi. A physical-chemical basis for distinguishing molecules active, as opposed to inactive, in promoting morphogenesis is established by the secondary structure of the resultant nucleic acid duplexes. This regulatory mechanism may be of broad import.
SELECTION FOR NURSING ABILITY AND ADULT WEIGHT IN MICE
Authors: Nagai J , Eisen E J , Emsley J A B , McAllister A J 
Published: April 2021

ABSTRACT
Three selection treatments were conducted for 12 generations in each of two base populations (P and Q): (1) increased nursing ability of the mother (n12), as measured by mean 12-day weight of eight young within a crossfostering set (MP and MQ lines), (2) increased adult (42-day) body weight of the offspring (w42) (WP and WQ lines), and (3) performance combining the two traits (n12 and w42) into a selection index (BP and BQ lines). Lines CP and CQ were maintained as unselected controls in each population. In each line-generation subclass, 92 single-pair matings were made and the offspring assigned to balanced crossfostering sets of four dams each. Regression coefficients of mean performance (in grams) on generations were 0.080 ±0.029 and 0.054 ± 0.031 for n12 in MP and MQ, and 0.680 ± 0.039 and 0.868 ± 0.051 for w42 in WP and WQ, respectively. The BP and BQ lines showed genetic gains in n12 (0.090 and 0.053, respectively) and w42 (0.576 and 0.696) intermediate between the performance of MP and WP, and MQ and WQ, respectively, except for n12 of BQ. Realized heritabilities for n12 were 0.16 ± 0.05 and 0.11 ± 0.06 and those for w42 were 0.40 ± 0.02 and 0.43 ± 0.03 for P and Q, respectively. The realized genetic correlations between n12 and w42 were 0.70 ± 0.07 and 0.73 ± 0.08 in P and Q, respectively. The ratios of the predicted to observed responses in MP, BP and BQ were 0.99, 1.03 and 0.89, respectively. However, the predicted and observed responses differed in MQ, WP and WQ; the ratios were 1.29, 0.65 and 0.65, respectively. The observed combined responses for n12 and w42 in the index lines (BP and BQ) were smaller than the optimum expected from index selection. A possible cause was that the estimated genetic correlations (0.22 ± 0.16 and -0.17 ± 0.16 for BP and BQ, respectively) and heritabilities (0.39 ± 0.03 and 0.28 ± 0.02, respectively) for w42 that were used to construct the selection index were smaller than the respective realized parameters.
SINGLE-TRAIT AND ANTAGONISTIC INDEX SELECTION FOR LITTER SIZE AND BODY WEIGHT IN MICE
Authors: Eisen E J 
Published: April 2021

ABSTRACT
Individual selection based on female performance only was conducted in four lines of mice: L+ for increased litter size, W+ for increased 6-week body weight, L-W+ for a selection index aimed at decreasing litter size and increasing 6-week body weight and L+W- for a selection index aimed at increasing litter size and decreasing 6-week body weight. A fifth line (K) served as an unselected control. All litters were standardized to eight mice at one day of age. Expected heritability was based on twice the regression of offspring on dam (h 2 d), which contains additive genetic variance due to direct (α2Ao) and maternal (α2 Am) effects and their covariance (αAoAm). Responses and correlated responses were measured either deviated (method 1) or not deviated (method 2) from the control line. Realized heritabilities (h2 R) for litter size were 0.19 ± 0.04 (1) and 0.16 ± 0.03 (2), which were similar to h2 d of 0.17 ± 0.04. The h2 R for 6-week body weight of 0.55 ± 0.07 (1) and 0.44 ± 0.07 (2) agreed with h2 d of 0.42 ± 0.02. Realized genetic correlations (r*GR) between litter size and 6-week body weight calculated from the double-selection experiment were 0.52 ± 0.10 (1) and 0.52 ± 0.13 (2), which were not significantly different from the base population estimate of r*Gd = 0.63 ± 0.14. Divergence (L-W+ minus L+W-) in the antagonistic index selection lines was 0.21 ± 0.01 index units (I = 0.305 PW - 0.436 PL, where PW and PL are the phenotypic values for 6-week body weight and litter size, respectively.). The h2 R of index units of 0.14 ± 0.02 calculated from divergence agreed with h2 d of 0.14 ± 0.04. Divergences in litter size (-0.19 ± 0.07) and 6-week body weight (0.46 ± 0.10) were in the expected direction. Antagonistic index selection yielded about one-half the expected divergence in litter size, while divergence in 6-week body weight was only slightly less than expected. Realized genetic correlations indicated that litter size, 6-week body weight and index units each showed positive pleiotropy with 3-week body weight, postweaning gain and weight at vaginal introitus and negative pleiotropy with age at vaginal introitus. Sex ratio and several components of fitness (days from joining to parturition, percent fertile matings and percent perinatal survival) did not change significantly in the selected lines.
SEX-LIMITED EXPRESSION OF GENE LOCI CONTROLLING FLAGELLAR MEMBRANE AGGLUTINATION IN THE CHLAMYDOMONAS MATING REACTION
Authors: Goodenough Ursula W , Hwang Carol , Warren A Jane 
Published: April 2021

ABSTRACT
Mutant strains of Chlamydomonas reinhardi that have lost their ability to undergo sexual agglutination via their flagellar tips have been induced to undergo zygotic cell fusion and meiosis, using a flagellar-directed antiserum. Genetic analysis of antiserum-mediated crosses involving five nonagglutinating mt + mutant strains reveals the following: (1) None of the mutations is linked to the mt locus. (2) All of the mutations are "sex-limited," meaning that they can be carried and transmitted by, but not expressed in, mt - cells. (3) Four of the mutations (imp-2, imp-5, imp-6, imp-7) are either allelic or closely linked to one another, with imp-8 defining a second locus.