bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NOTE ON THE MATERNAL EFFECT MUTANTS DAUGHTERLESS AND ABNORMAL OOCYTE IN DROSOPHILA MELANOGASTER
Authors: Mange Arthur P , Sandler L 
Published: January 2021

ABSTRACT
Two deficiencies for, and a dominant enhancer of, the second chromosome maternal effect mutant, "daughterless" (da), were induced with X-irradiation. Their properties were studied with respect to both da and the linked maternal effect mutant, "abnormal oocyte" (abo), with the following conclusions. (1) The most probable map positions of da and abo are: J–½–da–2½–abo, where J is a dominant marker located at 41 on the standard map. (2) The da locus is in bands 31CD-F on the polytene chromosome map; abo is to the right of 32A. (3) Because homozygous da individuals survive while individuals carrying da and a deficiency for da are lethal, it is concluded that da is hypomorphic. (4) From a weak da-like maternal effect in heterozygous da females induced by an "Enhancer of da," we have confirmed a previous report that (a) the amount of sex chromosome heterochromatin contributed by the father can influence the severity of the da maternal effect, and (b) the sex chromosome heterochromatin which influences the da effect is different from that which influences the abo effect. (5) The possibility that da and abo are in a special region of chromosome 2 concerned with the regulation of sex chromosome heterochromatin is strengthened by the observation that the Enhancer of da appears to rescue abnormal eggs produced by homozygous abo mothers. (6) The Enhancer of da is a translocation between chromosomes 2 and 3 with the second chromosome breakpoint in the basal heterochromatin; because the enhancing effect maps in this region of chromosome 2, it is possible that autosomal, as well as sex chromosomal, heterochromatin interacts with da and abo.
RADIATION GENETICS IN MICROORGANISMS AND EVOLUTIONARY CONSIDERATIONS
Authors: Kondo Sohei 
Published: January 2021

ABSTRACT
Recent knowledge of UV-resistance mechanisms in microorganisms is reviewed in perspective, with emphasis on E. coli. Dark-repair genes are classified into "excision" and "tolerance" (ability to produce a normal copy of DNA from damaged DNA). The phenotype of DNA repair is rather common among the microorganisms compared, and yet their molecular mechanisms are not universal. In contrast, DNA photoreactivation is the simplest and the most general among these three repair systems. It is proposed that DNA repair mechanisms evolved in the order: photoreactivation, excision repair, and tolerance repair. The UV protective capacity and light-inducible RNA photoreactivation possessed by some plant viruses are interpreted to be the result of solar UV selection during a rather recent era of evolution.
CYTOGENETICS OF CHROMOSOME PAIRING IN WHEAT
Authors: Riley Ralph 
Published: January 2021

ABSTRACT
Meiotic chromosome pairing in Triticum aestivum is controlled by genetic systems promoting and reducing pairing. The pairing of homoeologous chromosomes is prevented principally by the activity of a single locus (Ph) distally located on the long arm of chromosome 5B. In certain hybrids, supernumerary chromosomes (B chromosomes) from Aegilops species can compensate for the absence of chromosome 5B preventing or reducing homoeologous pairing. Temperature-dependent variants and colchicine sensitivity have been used to show that there are at least two stages in the G1 of meiosis at which the occurrence of meiotic pairing is determined. Wheat may differ from lily in the detailed organization of meiosis.
CHROMOSOME SEGREGATION MECHANISMS
Authors: Nicklas R Bruce 
Published: January 2021

ABSTRACT
Most aspects of chromosome distribution to the daughter cells in meiosis and mitosis are now understood, at the cellular level. The most striking evidence that the proposed explanation is valid is that it correctly predicts the outcome of experiments on living cells in which the experimenter (1) can determine the distribution of any chosen chromosome to a chosen daughter cell, (2) can induce a mal-orientation, and (3) can stabilize a mal-orientation, causing non-disjunction of a chosen bivalent. Recent reviews of chromosome distribution mechanisms are also considered, in an attempt to clarify the remaining unsolved problems.
THE DILEMMA OF SCIENCE AND MORALS
Authors: Stent Gunther S 
Published: January 2021

ABSTRACT
The conflicts between science and morals which still continue to arise despite the apparent hegemony of atheistic scientism over traditional Judeo-Christianity in the twentieth century reflect a basic contradiction in the metaphysical foundation of Western lives. As was set forth by Machiavelli, the contradiction inherent in Western ethics is that it is based on the simultaneous belief in both objectively valid moral truths and purely relative values of communal purpose. The achievements of twentieth century science have intensified these contradictions. Modern physics has put in question the validity of its own metaphysical basis, namely the belief in Natural Law, and modern biology has been unable to come to terms with the Cartesian dualism of body and soul. By contrast, Chinese lives are comparatively free of these contradictions, being founded on the philosophies of Confucianism and Taoism, to which the concepts of objectively valid truth or Natural Law are foreign. Recent developments in Western attitudes regarding science and morals can be interpreted as a movement away from the traditional belief in absolute truths towards a Chinese relativism.
SOME ACRIDINE-RESISTANT MUTATIONS OF BACTERIOPHAGE T4D
Authors: Rappaport Harriet , Russel Marjorie , Susman Millard 
Published: January 2021

ABSTRACT
Three new 9-aminoacridine (9AA) resistant mutations of bacteriophage T4D have been isolated and characterized. Two of the mutations, rs and rc, have identical patterns of acridine resistance, but they map on opposite sides of the rII region. In addition, rs has an effect on the plaque morphology of r mutations, whereas rc does not. The third mutation, ama, maps very close to rs but exhibits a different pattern of resistance to 9AA. None of the three is resistant to acridines by virtue of reduced permeability. Taken together with other mutations that have been previously characterized, these new mutations permit us to set the minimum number of acridine-sensitive processes in T4 development at four.
A FINE STRUCTURE MAP OF THE SALMONELLA HISTIDINE OPERATOR-PROMOTER
Authors: Ely Bert , Fankhauser David B , Hartman Philip E 
Published: January 2021

ABSTRACT
Over 100 regulatory mutations linked to the histidine (his) operon of S. typhimurium have been isolated. They all map in a region estimated to be several hundred base pairs in length located at one end of the his operon ("the hisO region"). The mutations are located at sixteen recombinationally separable sites or are deletions encompassing several sites. Data obtained from pairs of reciprocal three-point tests show that "constitutive" (high enzyme levels) and "promoter-like" (low enzyme levels) hisO mutations are interspersed on the genetic map. In a few crosses, recombination was not observed to occur between markers shown to occupy different sites based on behavior in other recombination tests.
EFFECTS OF POPULATION SIZE AND SELECTION INTENSITY ON RESPONSES TO DISRUPTIVE SELECTION IN DROSOPHILA MELANOGASTER
Authors: Barker J S F , Karlsson L J E 
Published: January 2021

ABSTRACT
Disruptive selection for sternopleural bristle number with opportunity for random mating was done in the four treatment combinations of two population sizes (40 pairs and 8 pairs of selected parents) and two selection intensities (1 in 40 and 1 in 2). In each generation, matings among selected parents were observed in a mating chamber, and progeny collected separately from each female parent. In the high number, high selection intensity treatment, divergence between the high and low parts ceased about generation 11. The isolation index increased rapidly to generation 3, but then fluctuated to termination of the population at generation 17. The overall isolation index was significant, indicating a real tendency to assortative mating. The failure of the isolation index to increase after generation 3 was attributed to lower average mating fitness of high males (due to inbreeding) and reduced receptivity of low females (due to a homozygous lethal gene with a large effect on sternopleural bristle number in heterozygotes). In the two low number treatments, isolation indices fluctuated from generation to generation with no obvious trends, and none of the overall isolation indices were significantly different from zero. The high number, low selection intensity treatment showed very little divergence, and one of the replicates showed, in contrast with expectation and the high number, high selection intensity treatment, a significant tendency to disassortative mating. Intense disruptive selection may lead to assortative mating.
THE EVOLUTIONARY ADVANTAGE OF RECOMBINATION
Authors: Felsenstein Joseph 
Published: January 2021

ABSTRACT
The controversy over the evolutionary advantage of recombination initially discovered by Fisher and by Muller is reviewed. Those authors whose models had finite-population effects found an advantage of recombination, and those whose models had infinite populations found none. The advantage of recombination is that it breaks down random linkage disequilibrium generated by genetic drift. Hill and Robertson found that the average effect of this randomly-generated linkage disequilibrium was to cause linked loci to interfere with each other's response to selection, even where there was no gene interaction between the loci. This effect is shown to be identical to the original argument of Fisher and Muller. It also predicts the "ratchet mechanism" discovered by Muller, who pointed out that deleterious mutants would more readily increase in a population without recombination. Computer simulations of substitution of favorable mutants and of the long-term increase of deleterious mutants verified the essential correctness of the original Fisher-Muller argument and the reality of the Muller ratchet mechanism. It is argued that these constitute an intrinsic advantage of recombination capable of accounting for its persistence in the face of selection for tighter linkage between interacting polymorphisms, and possibly capable of accounting for its origin.
THE TWO-LOCUS MODEL WITH SEX DIFFERENCES IN RECOMBINATION
Authors: Strobeck Curtis 
Published: January 2021

ABSTRACT
The criteria for stability of the equilibrium with D=0 are obtained for the two locus model with multiplicative or symmetric fitnesses when the recombination values in males and females are different. It is shown that if r is defined to be equal to the average of the recombination values in males and females, then the criteria are exactly the same as in the standard two locus model.—The equilibrium values with D≠0 are obtained for the symmetric fitness model. At this equilibrium, the absolute value of D is always greater (for the same average recombination value) if the recombination values in males and females differ than if they are equal.
RECIPIENT GENE DUPLICATION DURING GENERALIZED TRANSDUCTION
Authors: Stodolsky M 
Published: January 2021

ABSTRACT
An Hfrl3 ΔProA-lac deletion recipient, -ΔproA-lac-F-purE+-, has been utilized in a study of the origins of duplications formed during chromosome fragment integration. Among the Pro-Lac+ transductants, some have duplications spanning the F locus. These transductants are, or segregate, strains with F' episomes carrying genes of the duplication. Some of the duplications include purE+, a gene which is not coinherited with lac+ during bacteriophage P1- mediated transduction. Thus recipient genes have been duplicated during recombinant formation. Crossing-over models including replication steps provide a basis for explaining the duplication process.
GENETIC LIMITS OF THE XANTHINE DEHYDROGENASE STRUCTURAL ELEMENT WITHIN THE ROSY LOCUS IN DROSOPHILA MELANOGASTER
Authors: Gelbart William M , McCarron Margaret , Pandey Janardan , Chovnick Arthur 
Published: January 2021

Abstract
Experiments are described that provide an opportunity to estimate the genetic limits of the structural (amino acid coding) portion of the rosy locus (3: 52.0) in Drosophila melanogaster, which controls the enzyme, xanthine dehydrogenase (XDH) . This is accomplished by mapping experiments which localize sites responsible for electrophoretic variation in the enzyme on the known genetic map of null-XDH rosy mutants. Electrophoretic sites are distributed along a large portion of the null mutant map. A cis-trans test involving electrophoretic variants in the left- and right-hand portions of the map leads to the conclusion that the entire region between these variants is also structural. Hence most, if not all, of the null mutant map of the rosy locus contains structural information for the amino acid sequence of the XDH polypeptide. Consideration is given to the significance of the present results for the general problem of gene organization in higher eukaryotes.
REPAIR OF X-IRRADIATION DAMAGE IN TRIBOLIUM CASTANEUM STRAINS SELECTED FOR DIFFERENCES IN DEVELOPMENTAL RATES
Authors: Soliman M Hani 
Published: January 2021

ABSTRACT
Lines previously selected for different speed of development were found to differ in their spontaneous and induced wing abnormalities after single exposure to X-ray (10 KR) in Tribolium castaneum at 33° and 70% relative humidity. At the time of irradiation the mean developmental time (from egg to first day pupa) was 16.9, 18.8, 22.8 and 18.4 days for fast, intermediate, slow and unselected lines, respectively. There was no difference between males and females in their responses. The spontaneous rate (angular values) of wing abnormalities was 5.3%, 11.2%, 3.5% and 7.2%, and the corresponding induced values were 16.7%, 20.5%, 11.7% and 25.2% for fast, intermediate, slow and unselected lines, respectively. The difference between the spontaneous (due to selection) and the induced (due to selection and irradiation) rates indicates that slowing down development will probably increase the efficiency of the repair of the irradiation damage. This difference (angular values) was 11.4%, 9.4% and 8.1% for fast, intermediate and slow lines, respectively. Increasing developmental time by one day resulted in repairing 0.56% of the radiation damage. These results indicate that both the genetic and the developmental state of the line influence both induction and repair of the X-irradiation damage. The relationship between development, cell cycle, protein synthesis and repair is discussed.
THE BACILLUS SUBTILIS GENOME: REPLICATION-ORDER AND MAP-POSITION DISCREPANCIES—EVIDENCE FOR A SECOND ORIGIN
Authors: Copeland James C 
Published: January 2021

ABSTRACT
Replication order to map position discrepancies have been documented in B. subtilis. The discrepancies were found to occur whenever the genome of B. subtilis was replicated under a variety of physiological conditions and in both 168 and W23 strains. The earliest replicating marker involved in these discrepancies was thr versus purB and aroA versus recA. A detailed linkage analysis of the ura to argA region was consistent with its being a continuous linkage group. This led to the conclusion that an origin for new starts at replication exists between recA and aroA.
MITOCHONDRIAL GENETICS VII. ALLELISM AND MAPPING STUDIES OF RIBOSOMAL MUTANTS RESISTANT TO CHLORAMPHENICOL, ERYTHROMYCIN AND SPIRAMYCIN IN S. CEREVISIAE
Authors: Netter Pierre , Petrochilo Eric , Slonimski Piotr P , Bolotin-Fukuhara Monique , Coen Dario , Deutsch Jean , Dujon Bernard 
Published: January 2021

ABSTRACT
We have isolated 15 spontaneous mutants resistant to one or several antibiotics like chloramphenicol, erythromycin and spiramycin. We have shown by several criteria that all of them result from mutations localized in the mitochondrial DNA. The mutations have been mapped by allelism tests and by two- and three-factor crosses involving various configurations of resistant and sensitive alleles associated in cis or in trans with the mitochondrial locus ω which governs the polarity of genetic recombination. A general mapping procedure based on results of heterosexual (ω+ × ω-) crosses and applicable to mutations localized in the polar segment is described and shown to be more resolving than that based on results of homosexual crosses. Mutations fall into three loci which are all linked and map in the following order: ω-RI-RII-RIII. The first locus is very tightly linked with ω while the second is less linked to the first. Mutations of similar resistance phenotype can belong to different loci and different phenotypes to the same locus. Mutations confer antibiotic resistance on isolated mitochondrial ribosomel and delineate a ribosomal segment of the mitochondrial DNA. Homo- and hetero-sexual crosses between mutants of the ribosomal segment and those belonging to the genetically unlinked ATPase locus, OI, have been performed in various allele configurations. The polarity of recombination between RI, RII, RIII and OI decreases as a function of the distance of the R locus from the ω locus rather than as a function of the distance of the R locus from the OI locus.
DOSAGE COMPENSATION OF GENES ON THE LEFT AND RIGHT ARMS OF THE X CHROMOSOME OF DROSOPHILA PSEUDOOBSCURA AND DROSOPHILA WILLISTONI
Authors: Abraham Irene , Lucchesi John C 
Published: January 2021

ABSTRACT
We have investigated the occurrence of dosage compensation in D. willistoni and D. pseudoobscura, two species whose X chromosome is metacentric with one arm homologous to the X and the other homologous to the left arm of chromosome 3 of D. melanogaster. Crude extracts were assayed for isocitrate dehydrogenase (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?), and α-glycerophosphate dehydrogenase (chromosome 2) in D. willistoni, and for esterase-5 (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?) and amylase (chromosome 3) in D. pseudoobscura. Our results indicate that a mechanism for dosage compensation is operative in both arms of the X chromosome of these two species.
VARIATION OF SPONTANEOUS OCCURRENCE RATES OF CHROMOSOMAL ABERRATIONS IN THE SECOND CHROMOSOMES OF DROSOPHILA MELANOGASTER
Authors: Yamaguchi Osamu , Mukai Terumi 
Published: January 2021

ABSTRACT
After accumulating mutations by the aid of marked inversions, spontaneous occurrence rates of chromosome aberrations were estimated for 1148 chromosome lines that originated from five stem line second chromosomes of Drosophila melanogaster. In chromosome lines originating from three stem chromosomes (CH, PQ, and RT), mutations were accumulated for 7550, 7252, and 7256 chromosome generations, respectively, but no structural change was detected. For the chromosome lines that originated from the other two stem chromosomes, the situation was different: Twenty aberrations (19 paracentric inversions and 1 translocation between the second and the third chromosomes) during 45990 chromosome generations took place in the 500 chromosome lines derived from stem line chromosome (AW), and 92 aberrations (83 paracentric inversions, 6 pericentric inversions, 2 translocations between the second and the third chromosomes and 1 transposition) arose during 45006 chromosome generations in the 500 chromosome lines derived from stem line chromosome (JH). For the AW group the occurrence rate becomes 0.00043 per chromosome per generation for all aberrations and 0.00041 for inversions. For the JH group the corresponding rates are 0.00204 and 0.00198, respectively.—A non-random distribution of the breakpoint on the salivary gland chromosome was observed and the breakpoints were concentrated in the regions 26, 29, 33, and 34.—The cytoplasms and the chromosomes (other than the second chromosomes) were made approximately uniform throughout the experiments. Thus, this remarkable variability in the occurrence rate is most probably due to the differences in one or more chromosomal elements on the original five stem chromosomes. The mutable chromosomes (AW and JH) appear to carry a kind of mutator factor such as hi (Ives 1950).
THE EFFECT OF LINKAGE ON THE MEAN VALUE OF INBREDS DERIVED FROM A RANDOM MATING POPULATION
Authors: van Aarde I M R 
Published: January 2021

ABSTRACT
An expression is derived which accounts for the effect of linkage on the mean value of diploid inbreds. The original population is taken to be in Hardy-Weinberg equilibrium. It is shown that linkage will accelerate inbreeding depression. The precise nature of the acceleration is worked out for some special cases.
COMPARATIVE GENETICS OF THE T-EVEN BACTERIOPHAGES
Authors: Russell Richard L 
Published: January 2021

ABSTRACT
A system of amber mutants has been developed for each of the T-even bacteriophages T2 and T6, to complement those already available in T4. In T2 these mutants identify 52 genes, of which 49 are homologous with T4 genes; in T6 they identify 45 genes, of which 42 have T4 homologs, and an additional one which is homologous to a T2 gene not yet identified in T4. In both T2 and T6, recombination between mutants is characterized by considerable negative interference, which is correctable by a mapping function designed for T4. Recombinational maps of T2 and T6 constructed with these mutants have the same gene order and nearly the same gene spacings as in T4, with the exception of the tail fiber region; T2 and T6 appear to lack a localized recombinational expansion of this region found in T4. Homologous gene products from all three phages are in general interchangeable, with the exception of those from two apparently "co-adapted" tail fiber genes, 37 and 38. The general genetic similarity of all three phages suggests that they are analogous to races of higher organisms, retaining the capacity for genetic exchange despite some clear genetic differences and some incipient isolating mechanisms.
EFFECTS OF SR-SPIROCHETE INFECTION ON DROSOPHILA MELANOGASTER CARRYING INTERSEX GENES
Authors: Miyamoto Chieko , Oishi Kugao 
Published: January 2021

ABSTRACT
Three sex-transforming genes (ix, traD, and dsx) in D. melanogaster were examined with respect to possible interactions with the NSR strain of SR-spirochetes. The SR-spirochetes exerted a lethal effect on XY but not on XX individuals, regardless of whether they were phenotypically males, intersexes, or females. These results, taken together with those reported by Sakaguchi and Poulson (1963) on tra and 2X3A intersexes, both of which are resistant to the androcidal action of SR-spirochetes, support the interpretation that male susceptibility is a consequence of the single X condition.