bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENETICS OF CATALASE IN DROSOPHILA MELANOGASTER: RATES OF SYNTHESIS AND DEGRADATION OF THE ENZYME IN FLIES ANEUPLOID AND EUPLOID FOR THE STRUCTURAL GENE
Authors: Lubinsky Sharon , Bewley Glenn C 
Published: April 2021

ABSTRACT
A screen for allelic variants of the enzyme catalase indicated that the Cat+ locus is essentially monomorphic in D. melanogaster. Segmental aneuploidy was used to screen the genome for a dosage-sensitive region for catalase activity. One region, 75D-78A on the polytene chromosome map of 3L, exhibited a hyperploid/euploid ratio of enzyme activity of 1.5. Further dissection localized the region to 75D-76A. We suggest that this region contains the structural locus for catalase in D. melmogaster.
Simple methods have been developed using the specific inhibitor, 3-amino-1,2,4-triazole, for the direct analysis of rates of synthesis and degradation of the Cat+ gene product. Based on kinetic studies of catalase synthesis in flies aneuploid and euploid for region 75D-76B, we suggest that these techniques can be readily applied to an examination of mutants that control the expression of the structural gene for catalase in Drosophila.
QUANTITATIVE GENETIC ANALYSIS OF TEMPERATURE REGULATION IN MUS MUSCULUS. I. PARTITIONING OF VARIANCE
Authors: Lacy Robert C , Lynch Carol Becker 
Published: April 2021

ABSTRACT
Heritabilities (from parent-offspring regression) and intraclass correlations of full sibs for a variety of traits were estimated from 225 litters of a heterogeneous stock (HS/Ibg) of laboratory mice. Initial variance partitioning suggested different adaptive functions for physiological, morphological and behavioral adjustments with respect to their thermoregulatory significance. Metabolic heat-production mechanisms appear to have reached their genetic limits, with little additive genetic variance remaining. This study provided no genetic evidence that body size has a close directional association with fitness in cold eiivironments, since heritability estimates for weight gain and adult weight were similar and high, whether or not the animals were exposed to cold. Behavioral heat conservation mechanisms also displayed considerable amounts of genetic variability. However, due tc strong evidence from numerous other studies that behavior serves an important adaptive role for temperature regulation in small mammals, we suggest that fluctuating selection pressures may have acted to maintain heritable variation in these traits.
CENTRAL EQUILIBRIA IN MULTILOCUS SYSTEMS. I. GENERALIZED NONEPISTATIC SELECTION REGIMES
Authors: Karlin Samuel , Liberman Uri 
Published: April 2021

ABSTRACT
The generalized nonepistatic selection regime encompasses combinations of multiplicative and neutral viability effects distributed across a set of loci. These subsume, in particular, mixtures of the classical modes of multiplicative and additive fitness evaluations for multilocus traits. Exact analytic conditions for existence and stability of a multilocus Hardy-Weinberg (H-W) polymorphic equilibrium cmfiguration are ascertained. It is established that the central H-W polymorphism is stable only if the component loci are "overdominant" and sufficient recombination is in force. The H-W central equilibrium is never stable for tight linkage whenever some multiplicative selection effects are contributed by at least two of the loci involved. In the case of additive selection expression and individual overdominant loci, the H-W polymorphism is stable independently of the level of recombination. In the context of "natural" recombination schemes, "more recombination" enhances the stability 3f the H-W polymorphic equilibrium.
THE INTERCELLULAR DISTRIBUTION OF MUTATIONS INDUCED IN OOCYTES OF DROSOPHILA MELANOGASTER BY CHEMICAL AND PHYSICAL MUTAGENS
Authors: Traut H 
Published: April 2021

ABSTRACT
When females of Drosophila melanogaster are treated with chemical or physical mutagens, not only in one but also in both of the two homologous X chromosomes of a given oocyte, a recessive sex-linked lethal mutation may be induced. A method is described that discriminates between such "single" and "double mutations." A theory is developed to show how a comparison between the expected and the observed frequency of double mutations yields an indication of the intercellular distribution (random or nonrandom) of recessive lethal mutations induced by mutagenic agents in oocytes and, consequently, of the distribution (homogeneous or nonhomogeneous) of those agents.—Three agents were tested: FUdR (12.5, 50.0 and 81.0,μg/ml), mitomycin C (130.0 μg/ml) and X rays (2000 R, 150 kV). After FUdR feeding, no increase in the mutation frequency usually observed in D. melanogaster without mutagenic treatment was obtained (u=0.13%, namely three single mutations among 2332 chromosomes tested). After mitomycin C feeding, 104. single and three double mutations were obtained. All of the 50 mutations observed after X irradiation were single mutations. The results obtained in the mitomycin C and radiation experiments favor the assumption of a random intercellular distribution of recessive lethal mutations induced by these two agents in oocytes of D. melanogaster. Reasons are discussed why for other types of mutagenic agents nonrandom distributions may be observed with our technique.
REPRODUCTIVE ISOLATION WITH LITTLE GENETIC DIVERGENCE IN SYMPATRIC POPULATIONS OF BROWN TROUT (SALMO TRUTTA)
Authors: Ryman Nils , Allendorf Fred W , Ståhl Gunnar 
Published: April 2021

ABSTRACT
Two reproductively isolated demes of brown trout coexist in a small Swedish mountain lake, Lake Bunnersjoarna. We electrophoretically examined 102 specimens from that lake for 27 enzymes encoded by 54 loci. The two demes are fixed for different alleles at a lactate dehydrogenase locus (LDH-1); statistically significant allele frequency differences at five other loci further support the complete lack of gene flow between these demes. There are significant differences in growth rates between fish in the two demes, but no further morphological differentiation has been detected.——In light of these findings, the genetic distance between these populations is surprisingly small (NEI'S I=0.975). These demes represent one of the least genetically divergent, reproductively isolated sympatric pair of vertebrate populations that have been identified. The results are discussed from both an evolutionary and ecological perspective.
THE USE OF RESTRICTION ENDONUCLEASES TO MEASURE MITOCHONDRIAL DNA SEQUENCE RELATEDNESS IN NATURAL POPULATIONS. I. POPULATION STRUCTURE AND EVOLUTION IN THE GENUS PEROMYSCUS
Authors: Avise John C , Lansman Robert A , Shade Rosemary O 
Published: April 2021

ABSTRACT
In this study we introduce to natural population analysis a molecular technique that involves the use of restriction endonucleases to compare mitochondrial DNA (mtDNA) sequences. We have examined the fragment patterns produced by six restriction endonucleases acting upon mtDNA isolated from 23 samples of three species of the rodent Peromyscus. Our observations confirm the following conclusions derived from previous experiments with laboratory animals: (1) mtDNA within an individual appears homogeneous; (2) at least the majority of mtDNA present in an individual is inherited from the female parent. Our experiments demonstrate for the first time that there is detectable heterogeneity in mtDNA sequences within and among natural geographic populations of a species and that this heterogeneity can readily be used to estimate relatedness between individuals and populations. Individuals collected within a single locale show less than 0.5% sequence divergence, while those collected from conspecific populations separated by 50 to 500 miles differ by approximately 1.5%. The mtDNAs of the closely related sibling species P. polionotus and P. mniculutus differ from each other by 13 to 17%; nonsibling species differ by more than 20%. Qualitative and quantitative approaches to analysis of digestion patterns are suggested. The results indicate that restriction analysis of mtDNA may become the most sensitive and powerful technique yet available for reconstructing evolutionary relationships among conspecific organisms.
NUMERICAL ANALYSIS OF WEAK RANDOM DRIFT IN A CLINE
Authors: Luskin Mitchell , Nagylaki Thomas 
Published: April 2021

ABSTRACT
The equilibrium state of a diffusion model for weak random genetic drift in a cline is analyzed numerically. The monoecious organism occupies an unbounded linear habitat with constant, uniform population density. Migration is homogeneous, symmetric, and independent of genotype. A single diallelic locus with a step environment is investigated in the absence of dominance and mutation. The ratio of the variance of either gene frequency to the product of the expected gene frequencies decreases monotonically to a non-zero constant. The correlation between the gene frequencies at two points decreases monotonically to zero as the separation is increased with the average position fixed; the decrease is asymptotically exponential. The correlation decreases monotonically to a positive constant depending 011 the separation as the average position increasingly deviates from the center of the cline with the separation fixed. The correlation also decreases monotonically to zero if one of the points is fixed and the other is moved outward in the habitat, the ultimate decrease again being exponential. All the results are parameter free. Some asymptotic formulae are derived analytically.
THE INTERGRADATION, GENETIC INTERCHANGEABILITY AND INTERPRETATION OF GENE CONVERSION SPECTRUM TYPES
Authors: Lamb Bernard C , Ghikas Aglaia 
Published: April 2021

ABSTRACT
In the Pasadena strains of Ascobolus immersus, the gene conversion propperties of 29 induced (nine UV, nine NG, and 11 ICR-170) and nine spontaneous white-ascospore mutations have been studied. Each mutant was cyossed to three types of derived wild-type strains; single mutants often gave very different conversion results in the three types of crosses, with any or all of the following changes in: percentage with post-meiotic segregation among aberrant-ratio asci; percentage with conversion to wild type among aberrant-ratio asci; and in total conversion frequency. — These results are compared with those of LEBLON (1972 a, b) from Ascobolus immersus and Yu-SUN, WICRRAMARATNE and WHITEHOUSE (1977) from Sordaria breuicollis. It is shown that conversion spectrum types are not necessarily distinct, but can completely intergrade, on the criteria of both post-meiotic segregation frequency and direction of correction. Genetic differences between strains in the present work resulted in much interchangeability of spectrum types for the same mutation in different crosses; e.g., from type C in one cross to type B/D type in another cross, although the mutation is presumably of the same molecular type (addition or deletion frame shift, or base substitution) in each cross. These changes of conversion properties for a given mutation in different crosses mean that previous interpretations of spectrum types in terms of specific conversion properties for various molecular types of mutation are inapplicable, or inadequate on their own, to explain the present data. Other factors, such as heterozygous cryptic mutations or conversion control genes, are probably involved. Because of asymmetric hybrid DNA formation, correction properties may differ from observed conversion properties.
DUPLICATIONS IN CAENORHABDITIS ELEGANS
Authors: Herman Robert K , Madl James E , Kari Claire K 
Published: April 2021

ABSTRACT
Thirteen chromosomal duplications, all unlinked to their linkage group of origin, have been identified following X-irradiation. Ten are X-chromosome duplications, of which six are half-translocations on three autosomomal linkage groups and four are free fragments. Five of the half-translocations are homozygous fertile and two are recognizable cytologically as chromosome satellites, both of which show some mitotic instability. The free-X duplications show varying tendencies for loss. Three appear not to overlap in extent previously identified free-X duplications. The fourth carries genes from linkage group V, as well as X. Three duplications of a portion of linkage group II were identified and found to be free and quite stable in hyperploids. Some of the free duplications tend to disjoin from the X chromosome in males. New X-chromosome map data are presented.
CONTROL OF MALE REPRODUCTIVE BEHAVIOR BY THE CENTRAL NERVOUS SYSTEM OF DROSOPHILA: DISSECTION OF A COURTSHIP PATHWAY BY GENETIC MOSAICS
Authors: Hall Jeffrey C 
Published: April 2021

ABSTRACT
In gynandromorphs of Drosophila, a detailed examination was made of the association between male courtship behavior and the chromosomal genotype of various parts of the central nervous system. Mosaic flies that behave as males repeatedly show a shorter murtship than normal males. If there is to be male behavior, the posterior dorsal brain must be haplo-X on at least one side for occurrence of the early courtship events. tapping, following of females and wing extension. Licking (proboscis extension) has nearly the same focus but is submissive; that is, male tissue must be present in both left and right dorsal brain. The next courtship step, attempted copulation, has a focus (especially for actual genital contact) located in the thoracic ganglia, though apparently not in a discrete region. Attempted copulation, which can occur even in mosaics with a gravid abdomen, may be correlated with the presence of sex combs. The role of courtship foci are interpreted in terms of known sensory inputs to and functions of the major insect ganglia.
INDEPENDENT PRODUCTION OF CO2 SENSITIVITY BY NUCLEAR GENE DLY AND A TRANSMISSIBLE AGENT FROM DELAYED-RECOVERY DROSOPHILA MELANOGASTER
Authors: Clark M A , McCrady W B , Fielding C L 
Published: April 2021

ABSTRACT
Flies of stocks designated delayed-recovery by MCCRADY and SULERUD (1964) remain temporarily paralyzed after exposure to carbon dioxide. This condition is similar to CO2 sensitivity, which occurs in flies infected with the maternally transmitted sigma virus, but is due, at least in part, to the third chromosome mutant gene DlY. Because earlier work indicated that extracts of delayed-recovery flies could occasionally transmit CO2, sensitivity when injected into resistant recipients, we have tested the possibility that some delayed-recovery stocks contain a sigma-like transmissible virus, in addition to the Dly gene. We found that TDR-orange, a stock derived from the original delayed-recovery line, and temperature-cured populations of the same stock, both contain some agent that is transmissible by injection. TDR-BC3f, a stock derived by backcrossing through the male line to eliminate maternally transmitted factors, does not appear to contain such an infectious agent, but remains sensitive to CO2. These observations lead us to the conclusion that the originally described delayed-recovery stocks harbor an infectious extrachromosomal agent, in addition to possessing the Dly gene, and each is capable of producing a sensitivity to carbon dioxide.
ON THE NUMBER OF STABLE EQUILIBRIA AND THE SIMULTANEOUS STABILITY OF FIXATION AND POLYMORPHISM IN TWO-LOCUS MODELS
Authors: Feldman Marcus W , Libermann Url 
Published: April 2021

ABSTRACT
It is shown that in simple symmetric two-locus, two-allele constant fitness models the bound of four simultaneously stable equilibria previously accepted for general two-locus, two-allele models is exceeded. Situations with five and six stable equilibria are exhibited. These involve four chromosomal fixations and either one or two polymorphic stable equilibria.
AN UNSTABLE ALLELE OF THE am LOCUS OF NEUROSPORA CRASSA
Authors: Kinsey John A , Fincham J R S 
Published: April 2021

ABSTRACT
The mutant strain am126 was isolated, using the direct selection procedure, after nitrous acid mutagenesis. It produced neither measurable NADP-dependent glutamate dehydrogenase (GDH) nor immunologically cross-reacting material. That the am,126 strain produced some form of GDH product was shown by the fact that it complemented several other am mutant strains. The GDH formed by complementation between am126 and each of two other am mutants was relatively thermolabile, but could not be distinguished from wild-type GDH by electrophoresis in polyacrylamide gels. This, together with the relatively high yield of the complementation enzymes, suggests that the am126 product is a polypeptide chain not grossly abnormal in structure. The spontaneous revertant frequency was between 0.3 and 3 protatrophic revertants per 105 live cells. This frequency was at least 40 times greater than that for am19, which had the second highest spontaneous revertant frequency among the mutants tested. Neither meiosis nor mutagenesis increased the revertant frequency, nor did incubation at elevated temperatures lower it. Sixty-eight revertant strains were examined for thermostability of their GHD. All appeared to be identical to wild type. Seven of the revertant strains were also tested for instability with regard to Iorward mutation to am auxtrophy. None was found to be unstable. Models for the genetic instability of the am126 mutation are discussed.
SPORE KILLER, A CHROMOSOMAL FACTOR IN NEUROSPORA THAT KILLS MEIOTIC PRODUCTS NOT CONTAINING IT
Authors: Turner Barbara C , Perkins David D 
Published: April 2021

ABSTRACT
Three chromosomal factors called Spore killer (Sk) have been found in wild populations of Neurospora sitophila and N . intermedia. Sk resembles other examples of meiotic drive such as Segregation Distorter in Drosophila, Pollen killer in wheat, and Gamete eliminator in tomato. In crosses heterozygous for Sk, each ascus contains four viable black ascospores and four inviable, undersize, clear ascospores, with second-division segregations infrequent. The survivors contain the killer allele Skk, while unlinked markers segregate normally. Reciprocal crosses are identical. When crosses are homozygous for an allele of Sk, all eight ascospores are viable and black in most asci. (Many homozygms crosses have a background level of randomly occurring inviable spores; however, the pattern of 4 viable : 4 small clear ascospores is not found in any of the asci of Sk-homozygous crosses.)—killer (Sk-1K) and sensitive (Sk-1S) alleles occur in about equal numbers among a worldwide sample of N. sitophila strains, following no geographic pattern. No killer allele has been found in N . crassa. Sk-2K and Sk-3k, found in N . intermedia, are rare. Most N. intermedia strains are Sk-2S and Sk-3S, but some are wholly o r partially resistant to one or both of the killer alleles, while not themselves acting as killers. Sk-2K and Sk-2R are both specific in conferring resistance to Sk-2K, but not to Sk-3K. Likewise Sk-3K and Sk-3R are resistant specifically to Sk-3K, but not to Sk-2K. Resistance segregates as an allele of SkK.——Sk-2 and Sk-3 have been mapped near the centromere of linkage group I11 after introgression into N . crassa, where crossing over is normally 11 % between the proximal I11 markers acr-2 and leu-1. But crossing over is absent in this region when either of the killer alleles is heterozygous (Sk-2K x Sk-2S, Sk-3K x Sk-3S and Sk-2K X Sk-2R have been examined).
GENETIC CONTROL OF PHOSPHORUS ASSIMILATION IN NEUROSPORA CRASSA: DOSE-DEPENDENT DOMINANCE AND RECESSIVENESS IN CONSTITUTIVE MUTANTS
Authors: Metzenberg Robert L , Chia William 
Published: April 2021

ABSTRACT
Mutants called nuc-1C, constitutive for alkaline phosphatase synthesis, were isolated and mapped very close to nuc-1 mutants in which this enzyme is not expressed. nuc-1 is epistatic to nuc-1C. nuc-1C acts only if it is cis to normal nuc-1 function. The preparation of partial diploids heterozygous for various nuc-1 alleles is described; nuc-1C is dominant to nuc-1+, which in turn is dominant to nuc-1. In heterocaryons with nuc-1+, nuc-1C is dominant when it is present in high proportion, but essentially recessive if it is present in low proportions. In heterocaryons with nuc-1, nuc-1C is again dominant when present in high proportions, but in low proportions it "complements" to give essentially normal repressibility. A model of regulation consistent with these findings is presented.
ABSENCE OF DETECTABLE MITOCHONDRIAL RECOMBINATION IN PARAMECIUM
Authors: Adoutte André , Knowles Jonathan K , Sainsard-Chanet Annie 
Published: April 2021

ABSTRACT
An extensive search for recombination between mitochondrial markers was carried out in Paramecium tetraurelia. Thirty-two combinations, altogether involving 24 different markers, were studied. The markers belonged to the three main categories of mitochondrial mutations presently available in this organism. (a) Spontaneous or UV-induced antibiotic resistance mutations, most probably affecting mitochondrial ribosomes, (b) nitrowguanidine-induced antibiotic resistance markers displaying thermosensitivity or slow growth, enabling easy selection of possible wild-type recombinants, and (c) mitochondrial partial suppressors of a nuclear gene, probably corresponding to molecular alterations distinct from the preceding two categories. In addition, different genetic configurations were analyzed (i e., mutant x mutant, double-mutant x wild-type, etc.).——None of the combinations yielded any evidence for the occurrence of recombined genomes despite the fact that: (1) all of them were studied on a large scale involving the screening of at least several thousand mitochondrial genomes (often several millions), (2) in many of them the detection level was sufficiently high to enable the isolation of spontaneous mutants in control cells, and (3) in several of them, reconstitution experiments carried out in parallel show that the conditions were fully adequate to detect recombinant genotypes. The results are in marked contrast with those obtained on the few other organisms in which mitochondrial recombination has been studied, particularly Saccharomyces cerevisiae, in which mitochondrial recombination is intense.——The most likely basis for the various manifestations of mitochondrial genetic autonomy in Paramecium, described in this as well as in previous publications, is that the chondriome of this organism is made up of thousands of structurally discrete, noninteracting units.
VEGETATIVE INCOMPATIBILITY AND THE MATING-TYPE LOCUS IN THE CELLULAR SLIME MOLD DICTYOSTELIUM DISCOIDEUM
Authors: Robson Gillian E , Williams Keith L 
Published: April 2021

ABSTRACT
The genetic basis of vegetative incompatibility in the cellular slime mold, Dictyostelium discoideum, is elucidated. Vegetatively compatible haploid strains form parasexual diploids at a frequency of between 10-6 and 10-5, whereas "escaped" diploids are formed between vegetatively incompatible strains at a frequency of ~10-8. There is probably only a single vegetative incompatibility site, which appears to be located at, or closely linked to, the mating-type locus. The nature of the vegetative incompatibility is deduced from parasexual diploid formation between wild isolates and tester strains of each mating type, examination of the frequency of formation of "escaped" diploids formed between vegetatively incompatible strains, and examination of the mating type and vegetative incompatibility of haploid segregants obtained from "escaped" diploids.