bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHROMOSOMAL POLYMORPHISM AND FEMALE RECEPTIVITY IN A NATURAL POPULATION OF DROSOPHILA PERSIMILIS
Authors: Yu Hui Fang , Spiess Eliot B 
Published: April 2021

ABSTRACT
In a natural population of Drosophila persimilis (McDonald Ranch, Napa Valley, California), KL and MD chromosomal arrangement frequencies undergo a seasonal cycle, with MD common in spring and KL common in summer. Samples collected from spring and summer provided isofemale strains established as homozygous KL and MD pairs (kinlines) with each pair derived from a single heterokaryotype wild progenitor. Haploid doses of chromosomes 2 and 4 were controlled by marker-cross derivations of kinlines. Percentage onset of female receptivity was measured from cultures at 25° and at 15°, using ten kinlines from spring and nine from summer collections, with fast-mating hybrid males as standard testers. Mating tests consisted of 20 tester males x 20 females of specific age, karyotype, and kinline observed for 30 min. At 25° females became receptive at 48 hr after eclosion: parental line (KLi/KLi and MDi/MDi) females were approximately equal at 55 to 60% receptive, while among hybrids, MDi/MDj homokaryotype females were significantly less receptive (68%) than all other outbred combinations (73 to 77%). At 15°, females became receptive at four days of age, with increases on the fifth and sixth days: both parental line and outbred MD/MD females were significantly more receptive (28% at four days and 62% at six days) than all heterokaryotype females (20 to 26% at four days and 55 to 59% at six days), which in turn were more receptive than KL/KL parental and outbred females (10% at four days and 40% at six days). Heterosis was expressed at 25°, but not at 15°. Thus, dominance for female receptivity was temperature dependent. Females polymorphic for these third chromosomal karyotypes possess differential temperature sensitivity for onset of receptivity and are likely to contribute in a significant way to the observed seasonal frequency cycle in the natural population from which they have been derived.
SIMULTANEOUS STABILITY OF D=0 AND D≠0 FOR MULTIPLICATIVE VIABILITIES AT TWO LOCI
Authors: Karlin Samuel , Feldman Marcus W 
Published: April 2021

ABSTRACT
The two-locus, two-allele multiplicative viability model is investigated. It is shown that the well-known region of recombination values for which D = 0 is locally stable does not preclude the local stability of an equilibrium with D ≠ 0. This is shown numerically and is true for every case investigated in which both loci are overdominant and the viabilities not symmetric.
ANALYSIS OF THE ALBINO-LOCUS REGION OF THE MOUSE. I. ORIGIN AND VIABILITY
Authors: Russell Liane B , Russell W L , Kelly E M 
Published: April 2021

ABSTRACT
Numerous specific-locus experiments designed to test the mutagenic effect of external radiation have yielded, in over 3,600,000 animals observed, altogether 119 presumed mutations involving the c locus. Of these, 55 were viable and albino (cav)13, w ere viable and of various intermediate pigment types (cxv), four were subvital (cas and cxs)), seven were neonatally lethal albinos (cal), 28 prenatally lethal albinos (cal); 12 died untested. All of the prenatally lethal and at least one of the neonatally lethal c-locus mutations (caz classes) are probably deficiencies that we have analyzed extensively in other experiments. Since absence of the locus mimics albino in phenotype, the intermediates (cxv and cxs groups) probably resulted from intragenic changes. The class of viable albino mutants (cav) might include, in addition to intragenic changes, some extremely small deficiencies.—The effects on viability of c-locus lethals (cal's) in heterozygous condition are not drastic enough to be perceived in stocks of mixed genetic background except in the case of the two longest known deficiencies and a few others.—Analysis 3f the relation between radiation treatment and type of c-locus mutants obtained shows that the relative frequency of viable mutations, for each germ-cell type, is greater for low-LET than for neutron irradiation; however, the difference for any individual cell type is not significant. The majority (66.7%) of mutations derived from X-or γ-ray irradiated spermatogonia are viable, and the proportion of "intermediates" among these viables is similar to that among presumed spontaneous c-locus mutations. No significant dose-rate effect on the proportion of lethals could be demonstrated within the set of mutants induced by low-LET irradiation of spermatogonia. Although sets from other germ-cell stages are too small for statistical tests, the results for oocytes are similar, as far as they go. Furthermore, most of the c-locus mutations induced in spermatogonia, even by highdose-rate X-ray or γ irradiation, are of a type most likely to result from single-track events (62% cxv, cxs, and cav; plus 16% presumed deficiencies not involving the closest marker). These results support the view that most of the reduction in mutation frequency at low dose rates is not due to a change in relative proportion of two-track and one-track ionizing events.
ANALYSIS OF THE ALBINO-LOCUS REGION OF THE MOUSE. II. MOSAIC MUTANTS
Authors: Russell Liane B 
Published: April 2021

ABSTRACT
Among 119 mutations involving the c locus that were recovered in the course of mouse specific-locus experiments with external radiations, 16 were found in mosaic, or fractional, mutants. The number of additional c-locus fractionals that could have occurred in these experiments and, for a variety of reasons, might not have been clearly identified, probably does not exceed the present number.——There was no evidence for radiation induction of the fractionals, and even those cccurring in the irradiated groups may thus be assumed to be of spontaneous origin. Since only two mutations in the control groups were found in whole-body mutants, it appears that the bulk of spontaneous c-locus mu tations are fractionah——None of the mutations recovered in fractional mutants was homozygous lethal; 25% were viable intermediate alleles, and the remainder were albino-like mutants, all viable except for one subvital and one not tested.——Genetic tests of the fractionals indicated no major selection against the new mutations, either gametically or in the progeny.——For the group of fractionals as a whole, about one-half of the germinal tissue carried the mutation, indicating that the fractionals came from an overall blastomere population that was one-half mutant. Such a population could result from mutation in one strand of the gamete DNA, in a daughter chromosome derived from pronuclear DNA synthesis of the zygote, or in one of the first two blastomeres prior to replication. Since the mouse embryo does not stem from all of the cleavage products of the zygote, the frequency of fractionals observed underestimates the frequency of mutational events that result in two types of blastomeres.
THE CAN1 LOCUS OF SACCHAROMYCES CEREVISIAE: FINE-STRUCTURE ANALYSIS AND FORWARD MUTATION RATES
Authors: Whelan William L , Gocke Elmar , Manney Thomas R 
Published: April 2021

ABSTRACT
A system of strains and growth media was developed to allow efficient detection of forward mutation, reversion, complementation, and suppression at the canavanine-resistance (CAN1) locus of Saccharomyces cerevisiae. Genetic finestructure analysis revealed that the map length is at least 40, and possibly as much as 60 X-ray map units; this is the longest gene map yet reported in S. cerevisiae. Allelic complementation was not observed, despite testing of a large number of allele pairs, and alleles suppressible by the ochre suppressor SUP11 were absent from a sample of 48 spontaneous mutants and occurred infrequently (7%) among a sample of ultraviolet-induced mutants. Infrequent mutant types included canavanine-resistant mutants capable of arginine uptake and alleles thought to represent deletions or inversions. In contrast to previous raports in the literature, the spontaneous forward mutation rate at CAN1 did not increase during meiosis.
EXPRESSION OF RADIATION-INDUCED MUTATIONS AT THE ARGININE PERMEASE (CAN1) LOCUS IN SACCHAROMYCES CEREVISIAE
Authors: Gocke Elmar , Manney Thomas R 
Published: April 2021

ABSTRACT
In the yeast Saccharomyces cerevisiae, the expression of resistance to the L-arginine analog, L-canavanine, after mutagenesis, is strongly dependent on the metabolic state of the cell. The frequency of mutations recovered after exposure to ultraviolet light or X rays was measured under a variety of culture conditions. The results indicate that the frequency of mutants recovered is determined by the following three factors: (1) The potential mutants still possess enough permease activity to take up some of the cell poison, and some are therefore killed before they can express the mutant genotype. The sensitivity is strongly influenced by the endogenous free arginine, which is in turn influenced by the growth medium. (2) The rapid decay of the permease molecules and the inability of the potential mutants to resynthesize this protein results in a rapidly increasing chance of expression when selection is delayed. (3) During the time when the permease activity is decaying, repair of the mutagen-induced damage appears to occur.
EVIDENCE OF THE INSENSITIVITY OF THE α-inc ALLELE TO THE FUNCTION OF THE HOMOTHALLIC GENES IN SACCHAROMYCES YEASTS
Authors: Takano Isamu , Arima Kenji 
Published: April 2021

ABSTRACT
The possible function of the α-inc allele (an α mating-type allele that is insensitive to the function of the homothallic gene system) was investigated by means of protoplast fusion. The fusion of protoplasts prepared from haploid strains of α-inc HO HMα HMa and α ho hmα HMa gave rise mainly to nonmating clones (58 of 64 isolates) and a few clones (six of 64 isolates) showing a mating type. Thirty of the 56 nonmating clones showed the diploid cell size and 28 clones had a larger cell size. Tetrad analysis of the nonmating clones with diploid cell size indicated that they were a/α-inc diploid; the normal α allele in α/α-inc cells was preferentially switched to an a allele. This observation further indicated that the HO/ho HMα/hmα HMa/HMa genotype is effective for the conversion of the α to a and that the inconvertibility of the a-inc allele is due to the insensitivity of the mating-type allele to the functional combination of the homothallic genes. It was suspected that fusion products larger than diploid cells might have been caused by multiple fusion of protoplasts.
NON-MENDELIAN FEMALE STERILITY IN DROSOPHILA MELANOGASTER: CHARACTERIZATION OF THE NONINDUCER CHROMOSOMES OF INDUCER STRAINS
Authors: Picard Georges , Pelisson Alain 
Published: April 2021

ABSTRACT
In relation to non-Mendelian female sterility, Drosophila melanogaster strains can be divided into two main classes, inducer and reactive. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i + chromosome) can, when introduced by the paternal gamete into a reactive oocyte, give rise to females (denoted SF) showing more-or-less reduced fertility. As long as i + chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor follows Mendelian segregation patterns. In contrast, in heterozygous i+/r females, a varying proportion of r chromosomes may irreversibly acquire I factor, independently of classical genetic recombination, by a process called chromosomal contamination. The contaminated reactive chromosomes behave as i + chromosomes.—In the present paper, evidence is given that the Luminy inducer strain displays a polymorphism for two kinds of second chromosomes. Some of them are i +, while others, denoted io, are unable t3 induce any SF sterility when introduced by paternal gametes into reactive oocytes. They are also unable to induce contamination of r chromosomes, but, like r chromosomes, they may be contaminated by i+ chromosomes in SF or RSF females. The study of the segregation of i + and io second chromosomes in the progeny of heterozygous Luminy males and females leads to the conclusion that on chromosome 2 of the Luminy stock the I factor is at a single locus. —XI second and third io chromosomes have been found in several inducer strains. Since these chromosomes can be maintained with i + chromosomes in inducer strains in spite of their ability to be contaminated in RSF females, it can be concluded that chromosomal contamination does not take place in females of inducer strains. This implies that contamination occurs only in cells having cytoplasm in a reactive state.
SELECTION ON RECOMBINATION IN A MULTI-LOCUS SYSTEM
Authors: Charlesworth D , Charlesworth B 
Published: April 2021

ABSTRACT
The model of WILLS and MILLER (1976) for selection on recombination rates in finite populations was studied by means of a computer model involving 80 selected loci and a linked or unlinked modifier gene affecting the map length occupied by the selected loci. The selected loci were subject to heterozygote advantage, and multiplicative fitness interactions between loci were assumed. In all cases studied, selection for reduction in recombination outweighed any selection for increased recombination that may have been present.
A MATHEMATICALLY TRACTABLE FAMILY OF GENETIC MAPPING FUNCTIONS WITH DIFFERENT AMOUNTS OF INTERFERENCE
Authors: Felsenstein Joseph 
Published: April 2021

ABSTRACT
By extension of the argument of KOSAMBI (1944), a family of mapping functions can be derived, which has a parameter regulating the intensity of interference. Different values of this parameter yield the HALDANE (1919) and KOSAMBI mapping functions as special cases. The parameter is the coincidence coefficient for nearby small intervals. The family includes mapping functions for negative interference. A simple rule for combining recombination fractions in adjacent intervals is also obtained.
CENTRAL EQUILIBRIA IN MULTILOCUS SYSTEMS. II. BISEXUAL GENERALIZED NONEPISTATIC SELECTION MODELS
Authors: Karlin Samuel , Liberman Uri 
Published: April 2021

ABSTRACT
This paper is a continuation of the paper "Central Equilibria in Multilocus Systems I," concentrating on existence and stability properties accruing to central H-W type equilibria in multilocus bisexual systems acted on by generalized nonepistatic selection forces coupled to recombination events. The stability conditions are discussed and interpreted in three perspectives, and the influence of sexual differences in linkage relationships together with sex-dependent selection is appraised. In this case we deduce that the stability conditions of the H-W polymorphism in the bisexual model coincide exactly with the conditions for the corresponding monoecious model, provided that the recombination distribution imposed is that of the arithmetic mean of the male and female recombination distributions. A second concern has the same recombination distribution for both sexes, but contrasting selection regimes between sexes. It is then established that, with respect to discerning the relevance of the H-W equilibrium, there is an equivalent monoecious selection regime which is an appropriate "weighted combination" of the male and female selection forms. Finally, in the case where the selection and recombination structures are both sex dependent, a hierarchy of comparisons is elaborated, seeking to unravel the nature of selection-recombination interaction for monoecious versus diocecious systems.
HISTIDINE MUTANTS REQUIRING ADENINE: SELECTION OF MUTANTS WITH REDUCED hisG EXPRESSION IN SALMONELLA TYPHIMURIUM
Authors: Johnston H Mark , Roth John R 
Published: April 2021

ABSTRACT
A method is described for the selection of Salmonella typhimurium mutants with reduced levels of hisG enzyme activity. This method is based on the fact that the hisG enzyme catalyzes the consumption of ATP in the first step of histidine biosynthesis. Normally, this reaction is closely regulated, both by feedback inhibition and by repression of the operon. However, conditions can be set up that result in the uncontrolled use of adenine in histidine biosynthesis. Cells grown under these conditions become phenotypic adenine auxotrophs. Some revertant clones that no longer require adenine contain mutations in hisG, hisE, or the his-control region. The hisG mutations are of all types (non-sense, frameshift, missense, deletion and leaky types), and they map throughout the hisG gene.
THE GENETICS OF A SMALL AUTOSOMAL REGION OF DROSOPHILA MELANOGASTER CONTAINING THE STRUCTURAL GENE FOR ALCOHOL DEHYDROGENASE. II. LETHAL MUTATIONS IN THE REGION
Authors: Woodruff R C , Ashburner M 
Published: April 2021

ABSTRACT
Forty-seven lethal mutations and alleles of nine visible loci (including alcohol dehydrogenase) have been mapped by both deficiency mapping and, in most cases, by recombination mapping to a small region (34D-35C) of chromosome arm 2L of Drosophila melanogaster. The lethals fall into approximately 21 complementation groups, and we estimate that the total number of lethal plus visible complementation groups within the 34-band deficiency, Df(2L)64j, is approximately 34, a remarkable numerical coincidence. The possible genetic significance of this coincidence is discussed. Lethals mapping close to the structural gene for alcohol dehydrogenase, both distally and proximally, have been identified and will be used for the construction of selective crosses for the study of exchange within this locus. Despite many abnormal cytological features (e.g., ectopic pairing, weak points) region 35 of chromosome arm 2L does not display any unusual genetic features; indeed, in terms of the aniount of recombination per band and the average map distance between adjacent loci, this region is similar to that between zeste and white on the X chromosome.
ANALYSIS OF THE ALBINO-LOCUS REGION OF THE MOUSE. III. TIME OF DEATH OF PRENATAL LETHALS
Authors: Russell Liane B , Raymer G D 
Published: April 2021

ABSTRACT
The stage at which homozygotes die was determined for 28 mutations (general symbol c*) at the albino (c) locus, of which 26 had earlier been found to be probably prenatally lethal. Within each of the mutant stocks, the uterine contents of c*/cch females, made pregnant either by c*/cch males ("Ex" series) or by cch/cch males ("CO" series), were examined between 13 and 17 days postconception. Altogether, 743 females were dissected and 7197 corpora lutea (representing ovulations) counted. In selected stocks, an additional 40 and 13 females were dissected on days seven or nine, respectively.— In each of the 26 presumed prenatally lethal mutants, there was a deficiency of living fetuses in the Ex, as compared with the CO, group. Overall, this deficiency was 23.6% (expectation, 25% c*/c*). All meaningful excesses were in numbers either of moles (death shortly before, during, or just after implantation), or of early preimplantation losses. Homozygotes in none of the mutant stocks die between days nine and 19 postconception. Of 24 c-locus mutants known to be deficiencies since they lack the closely linked Mod-2, 13 clearly kill before implantation, ten around implantation, and me neonatally. The c and Mod-2 loci and the region between them are not needed for intrauterine survival.—There are indications that the distinction between early-preim-plantation death and implantation death may, in a general way, be related to length of the deficiency.
AN UNSTABLE NUCLEAR GENE IN PHYCOMYCES
Authors: Delbrück M , Ootaki T 
Published: April 2021

ABSTRACT
A gentic instability in Phycomyces is described that appears to be associated with a single nuclear gene, dar. The wild type is able to take up riboflavin and its toxic analogue, deaza-riboflavin, from nanomolar concentrations in the medium. The mutants are unable to take up riboflavin and are resistant to deaza-riboflavin. Forward and reverse mutation rates are estimated to be 4 × 10-5 and 2 × 10-3 per nuclear division. Independently arisen dar mutants do not complement in heterokaryons. The mutant alleles are almost completely recessive. The phenotype of spores is not determined cell-autonomously, but is strongly influenced by the allele ratio among the nuclei in the sporangium of origin.
LETHALS, STERILES AND DEFICIENCIES IN A REGION OF THE X CHROMOSOME OF CAENORHABDITIS ELEGANS
Authors: Meneely Philip M , Herman Robert K 
Published: April 2021

ABSTRACT
Twenty-one X-linked recessive lethal and sterile mutations balanced by an unlinked X-chromosome duplication have been identified following EMS treatment of the small nematode, Caenorhabditis elegans. The mutations have been assigned by complementation analysis to 14 genes, four of which have more than one mutant allele. Four mutants, all alleles, are temperature-sensitive embryonic lethals. Twelve mutants, in ten genes, are early larval lethals. TWO mutants are late larval lethals, and the expression of one of these is influenced by the number of X chromosomes in the genotype. Two mutants are maternal-effect lethals; for both, oocytes made by mutant hermaphrodites are rescuable by wild-type sperm. One of the maternal-effect lethals and two larval lethals are allelic. One mutant makes defective sperm. The lethals and steriles have been mapped by recombination and by complementation testing against 19 deficiencies identified after X-ray treatment. The deficiencies divide the region, about 15% of the X-chromosome linkage map, into at least nine segments. The deficiencies have also been used to check the phenotypes of hemizygous lethal and sterile hermaphrodites.
THE GENETICS OF MELANISM IN MALACOSOMA DISSTRIA HÜBNER (LEPIDOPTERA: LASIOCAMPIDAE)
Authors: Lorimer Nancy 
Published: April 2021

ABSTRACT
The forest tent caterpillar is polymorphic far two melanic genes affecting wing color of moths. These are the first genetically determined morphological traits reported for the genus. Dark (D) is a sex-limited, autosomal dominant with a phenotype of dark brown males. Frequencies in population samples varied from 8 to 44%. Characteristics of Dark and nonmelanic males were compared. Larval development times, larval survival and pupal weights were not significantly different, but mean fecundity was higher for females with Dark progeny. Band (b), a darkened area across the forewings, occurred in low frequency in both sexes.
MUTATIONS OF CHINESE HAMSTER SOMATIC CELLS FROM 2-DEOXYGALACTOSE SENSITIVITY TO RESISTANCE
Authors: Claverie Jean-Michel , De Souza Aristide Comlan , Thirion Jean-Paul 
Published: April 2021

ABSTRACT
In Chinese hamster somatic cells, the spontaneous change of phcnotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la LURIA and DELBRUCK (1943) for four Chinese hamster cell strains derived from V79. The results are consistent with true mutational events. The mutation rates are in the range of 1 to 3.5 × 10-5 per cell per generation. The relationship between the 2-deoxygalactose resistance and the galactokinase markers is discussed.
INTERFERENCE IN GENETIC CROSSING OVER AND CHROMOSOME MAPPING
Authors: Stam P 
Published: April 2021

ABSTRACT
This paper proposes a general model for interference in genetic crossing over. The model assumes serial Occurrence of chiasmata, visualized as a renewal process along the paired (or pairing) chromosomes. This process is described as an underlying Poisson process in which the Ist, n + 1th, 2n + 1th, etc., events are to be interpreted as realized chiasmata. Chromatid interference is described in terms of the probabilities that two successive chiasmata involve two, three or four different chromatids. Several characteristics of this model, e.g., the cytological and genetic mapping function and the density of chiasmata along the chromosomes, are discussed. Some aspects of other interference models are briefly discussed.