bluuebunny/crossref_metadata_2025_split huggingface dataset:
Porosity and the Transnational: Travelling Theory between Naples and Frankfurt (Walter Benjamin, Asja Lacis and Ernst Bloch)
Authors: Smith Douglas 
Published: January 2021

Abstract
Since its foregrounding in Walter Benjamin and Asja Lacis’s essay on Naples in 1925, the concept of porosity has become a topos in discussions of that city, of Italy and of urban planning in general, to the point of receiving criticism in some quarters for its imprecision and over-use. The aim of this article is to explore the background to the term and its possible relevance to more recent transnational models of culture. This involves tracing the emergence of porosity in the work of Germanophone intellectuals travelling in Italy in the 1920s and its relation to the paradigm of travelling theory developed by Edward Said, itself one of the precursors of current models of transnationalism. Ultimately, the history of porosity reveals weaknesses and strengths that anticipate some of the problems and opportunities encountered by present attempts to understand cultural identity and interaction in transnational terms.
ENZYME VARIABILITY IN THE DROSOPHILA WILLISTONI GROUP. IV. GENIC VARIATION IN NATURAL POPULATIONS OF DROSOPHILA WILLISTONI
Authors: Ayala Francisco J , Powell Jeffrey R , Tracey Martin L , Mourão Celso A , Pérez-Salas Santiago 
Published: January 2021

ABSTRACT
We describe allelic variation at 28 gene loci in natural populations of D. willistoni. Seventy samples were studied from localities extending from Mexico and Florida, through Central America, the West Indies, and tropical South America, down to South Brazil. At least several hundred, and often several thousand, genomes were sampled for each locus. We have discovered a great deal of genetic variation. On the average, 58% loci are polymorphic in a given population. (A locus is considered polymorphic when the frequency of the most common allele is no greater than 0.95). An individual fly is heterozygous, on the average, at 18.4% loci.—Concerning the pattern of the variation, the most remarkable finding is the similarity of the configuration of allelic frequencies from locality to locality throughout the distribution of the species. Our observations support the conclusion that balancing natural selection is the major factor responsible for the considerable genetic variation observed in D. willistoni.
GENETIC MECHANISMS OF RARE MATINGS OF THE YEAST SACCHAROMYCES CEREVISIAE HETEROZYGOUS FOR MATING TYPE
Authors: Gunge Norio , Nakatomi Yasuo 
Published: January 2021

ABSTRACT
Yeast heterozygous for mating type lacks the ability to conjugate as judged by the mass-mating technique and accordingly is designated "non-mater". However, the non-mater shows rare mating ability with a frequency of less than 10−6. In the present study, the RD auxotroph mating method was mainly employed with the intention of examining the rare mating ability of various non-maters, using lactate ethanol minimal medium as a selective medium for hybridization. Crosses of aα × a, aα × a, aaα × a, aαα × a, etc. resulted in the production of respective hybrids with a relatively high frequency of about 10−6 to 10−7, whereas crosses of aaα × a, aαα × α, aaαα × a, aaαα × α, etc. resulted in hybrids with an extremely low frequency of about less than 10−8. Genetic analyses revealed that the rare matings were mostly caused by the presence of cells derived from the non-maters in which mating type had converted to a homozygous genotype. Mitotic recombination was shown to be a likely explanation for most of the conversion, judging from associated exchange of an outside marker, thr4. By successive employment of the RD auxotroph mating method, it was possible to produce a series of polyploid yeasts, triploids to octoploids. The DNA content and the cell volume were observed to increase parallel to the elevated ploidy states.
DIRECTED EVOLUTION OF METABOLIC PATHWAYS IN MICROBIAL POPULATIONS. I. MODIFICATION OF THE ACID PHOSPHATASE pH OPTIMUM IN S. CEREVISIAE
Authors: Francis J C , Hansche P E 
Published: January 2021

ABSTRACT
An experimental system for directing the evolution of enzymes and metabolic pathways in microbial populations is proposed and an initial test of its power is provided.—The test involved an attempt to genetically enhance certain functional properties of the enzyme acid phosphatase in S. cerevisiae by constructing an environment in which the functional changes desired would be "adaptive". Naturally occurring mutations in a population of 109 cells were automatically and continuously screened, over 1,000 generations, for their effect on the efficiency (Km) and activity of acid phosphatase at pH 6, and for their effect on the efficiency of orthophosphate metabolism.—The first adaptation observed, M1, was due to a single mutational event that effected a 30% increase in the efficiency of orthophosphate metabolism. The second, M2, effected an adaptive shift in the pH optimum of acid phosphatase and an increase in its activity over a wide range of pH values (an increment of 60% at pH 6). M2 was shown to result from a single mutational event in the region of the acid phosphatase structural gene. The third, M3, effected cell clumping, an adaptation to the culture apparatus that had no effect on phosphate metabolism.—The power of this system for directing the evolution of enzymes and of metabolic pathways is discussed in terms of the kinetic properties of the experimental system and in terms of the results obtained.
TEMPERATURE-SENSITIVE MUTATIONS IN DROSOPHILA MELANOGASTER. IX. DOMINANT COLD-SENSITIVE LETHALS ON THE AUTOSOMES
Authors: Rosenbluth Raja , Ezell Dean , Suzuki David T 
Published: January 2021

ABSTRACT
Ethyl methanesulfonate-treated autosomes were screened for the presence of dominant cold-sensitive (DCS) lethal mutations in Drosophila melanogaster. None was found among 6,552 treated and 168 untreated third chromosomes. Twenty-three DCS-L chromosomes which caused death at 17°C but survived at 22°C and 29°C were recovered from 5,046 mutagenized chromosome 2's.—The DCS-L mutations all mapped around dp and appeared to be functionally allelic. Lethality of heterozygotes for most of the DCS-L's occurred over a prolonged interval from the embryonic through the larval instars. Prolonged incubation at 17°C did not demonstrate any maternal effect on zygotic survival.
DENSITY TRANSFER STUDIES OF DNA ISOLATED FROM BACILLUS SUBTILIS AFTER EXPOSURE TO PHENETHYL ALCOHOL
Authors: Zyskind J Weaver , Pattee P A 
Published: January 2021

ABSTRACT
The aim of this study was to determine whether there are specific weak points in the Bacillus subtilis chromosome and if so whether the replication point is the site of breakage. To answer these questions, B. subtilis chromosomes were partially labeled with 5-bromodeoxyuridine (5-BUdR). Sheared or unsheared preparations of partially labeled chromosomes which may or may not contain replication forks were analyzed for the distribution of genetic markers in a CsCl density gradient. Two sets of experiments based upon the density transfer experiments of Yoshikawa and Sueoka (1963) were performed: (1) experiments in which the origin of the chromosome was labeled and (2) experiments in which the terminus of the chromosome was labeled. In the first experiment, strain 23 (thy-, his-) spores were germinated in the presence of 5-BUdR for various lengths of time and then transferred to fresh medium containing phenethyl alcohol (PEA) and thymidine (TdR). The DNA was isolated before and after transfer to PEA and TdR. In the second experiment strain 23 (thy-, his-) spores were germinated in the presence of TdR and then PEA was added. After various lengths of time transfer was made to fresh medium containing PEA and 5-BUdR. The DNA was extracted by an extremely gentle technique to avoid breakage and centrifuged in a CsCl density gradient. PEA was added to the germinated spores to prevent dichotomous replication, but PEA did not prevent dichotomous replication in any of these experiments. This contradicts the conclusion of others that PEA prevents the chromosome from entering a new round of replication, but allows the chromosome to complete the round of replication already begun. The following observations offer support for the hypothesis that the replication point is a weak point in the chromosome: (1) when conditions were created to obtain partially labeled chromosomes with replication points: (a) labeled markers appeared at the hybrid density, (b) unlabeled markers appeared at the light density, (c) shearing of the DNA had little effect on the CsCl density gradient, except on a small proportion of labeled markers which had not appeared at the hybrid density prior to shearing; (2) when conditions were created to obtain partially labeled chromosomes with no replication points: (a) the majority of DNA molecules appeared at an intermediate density between the hybrid and the light densities, (b) the labeled and unlabeled markers appeared in the intermediate peak with approximately the same ratio as in the DNA preparations, (c) the labeled markers were found in the intermediate peak except where dichotomous replication had occurred, (d) after shearing, the labeled markers appeared at the hybrid density and the unlabeled markers appeared at the light density. Thus it is concluded that the replication point is a weak point in the B. subtilis chromosome where breakage easily occurs.
FINE STRUCTURE ANALYSIS OF THE ade3 LOCUS IN SACCHAROMYCES CEREVISIAE
Authors: Jones Elizabeth W 
Published: January 2021

ABSTRACT
Twenty-six spontaneous mutants at the ade3 locus of Saccharomyces cerevisiae have been mapped and characterized with respect to revertibility, osmotic remediability and temperature sensitivity. Twelve of the twenty-six are temperature sensitive, 25 of 26 are osmotic remedial and 21 of 26 revert. Two of the mutants map as deletions. At least five of the 26 are nonsense mutations but are also, unexpectedly, osmotic remedial. Three nonsense mutations are also temperature sensitive, again an unexpected result. The two multisite mutations are both temperature sensitive and osmotic remedial. For mutants at this locus osmotic remediability and temperature sensitivity cannot be considered diagnostic criteria for missense mutations.
GLUTAMATE OXALOACETATE TRANSAMINASE (GOT) GENETICS IN THE MOUSE: POLYMORPHISM OF GOT-1
Authors: Chapman Verne M , Ruddle Frank H 
Published: January 2021

ABSTRACT
We have examined a polymorphism for the soluble glutamate oxaloacetate (GOT-1) isozyme system which was found in the Asian mouse Mus castaneus. Variants of GOT-1 segregate as though they are controlled by codominant alleles for a single autosomal locus which we have designated Got-1. No close linkage of genes for soluble and mitochondrial forms of the enzyme, GOT-1 and GOT-2 respectively, was observed. Furthermore, no close linkage of Got-1 and the loci c, Gpi-1, Mod-2, Mod-1, Ld-1, Gpd-1, Pgm-1 or Gpo-1 was observed. Our results demonstrate the utility of sampling Mus from diverse populations to extend the repertoire of polymorphic loci and the genetic linkage map.
GENETIC CHANGE OF RECOMBINATION VALUE IN DROSOPHILA MELANOGASTER. I. ARTIFICIAL SELECTION FOR HIGH AND LOW RECOMBINATION AND SOME PROPERTIES OF RECOMBINATION-MODIFYING GENES
Authors: Kidwell Margaret Gale 
Published: January 2021

ABSTRACT
A high and low selection line were formed by individual selection of females on the basis of their recombination. In the high line, recombination between Gl and Sb was increased from 14.8 percent to about 30 percent in twelve generations, when a plateau was apparently reached. Realized heritability was 0.12. The absence of a response to selection for low recombination is attributed mainly to genetic random drift, and partially to directional dominance and directional gene frequencies. Natural selection was found to act against increases of recombination above a level of about twenty percent in the measured interval. High recombination tended to be recessive to low recombination. In both selected lines and unselected stocks, intervals proximal to the centromere tended to have a higher recombination variance than distal intervals.
GENETIC CHANGE OF RECOMBINATION VALUE IN DROSOPHILA MELANOGASTER. II. SIMULATED NATURAL SELECTION
Authors: Kidwell Margaret Gale 
Published: January 2021

ABSTRACT
Selection of Gl-Sb coupling heterozygotes was carried out for more than one hundred generations commencing with six independent lines drawn from a common base population. Population sizes were eight, sixteen and forty-eight parents per generation. The effect of natural selection on recombination value was measured by sampling and testing females at varying intervals of time. There was a significant reduction in percentage recombination between Gl and Sb from fifteen to a level between five and ten in four out of six of the original lines. In most cases this reduction occurred rather rapidly after the initiation of the experiment. In the remaining two lines there was no significant decrease in recombination value; there was, however, a significant increase in at least one subline of this group. The rapid rate of change of recombination value is most readily explained by the presence of a recombination modifying gene which is linked to the modified region. Genetic random drift was again shown to have an important effect on changes in recombination value in small populations. High recombination was almost completely recessive to low recombination in the one case examined. Lethal genes were fixed in sheltered regions of unmarked third chromosomes in five lines or sublines. These results are discussed in relation to the mode of development of permanent heterozygosity in some species of plants.
EXPERIMENTALLY DETERMINED, TWO LOCUS FITNESSES OF DROSOPHILA MELANOGASTER MALES
Authors: Wilson Jerome 
Published: January 2021

ABSTRACT
A pilot demonstration of experimental fitness estimation utilizing pedigree data from D. melanogaster was described. Fitnesses were obtained for the male segregants of the two "complex loci," spineless–spineless aristapedia and radius incompletus–inturned. A good fit between selection model and data was obtained, perhaps because the experimental design largely eliminated concerns of frequency or density-dependent selection and assortative mating. The selection model assumed that net fitness was divided into two components: an "early" component operative from conception to the time of observation in the generation interval, and a late component operative from the time of observation to the time of gamete pool formation. These fitness components were roughly descriptive of the physiological components viability and reproductive ability. No simple systematic relationship between the fitness of two-locus genotypes and the marginal one-locus fitness emerged. These conclusions were based on relatively precise (by current standards) fitness estimates. It was argued that pedigree data is highly desirable for fitness estimation.
GENETICS OF THE ST SEROTYPE SYSTEM IN TETRAHYMENA PYRIFORMIS, SYNGEN 1
Authors: Grass Frank S 
Published: January 2021

ABSTRACT
Genetic analyses using lines of Tetrahymena pyroformis manifesting different serotypes indicate that the St serotypes are governed by alleles at a single genetic locus. These alleles are termed StA and StC. The St locus is not closely linked to any of the other well-studied loci examined. Differentiation in StA/StC heterozygotes follows a pattern very similar to that observed with lines heterozygous at the other loci. Initially both alleles are expressed, but as the synclone divides, lines develop that manifest one allele or the other but not both. The time of differentiation is very early in the clonal life cycle, and the output ratio is eccentric. The pattern of development of the St locus places it in a category with the mating type and H serotype loci.
AN INSERTIONAL TRANSLOCATION IN NEUROSPORA THAT GENERATES DUPLICATIONS HETEROZYGOUS FOR MATING TYPE
Authors: Perkins David D 
Published: January 2021

ABSTRACT
In strain T(I⇉II)39311 a long interstitial segment is transposed from IL to IIR, where it is inserted in reversed order with respect to the centromere. In crosses of T x T essentially all asci have eight viable, black spores, and all progeny are phenotypically normal. When T(I⇉II)39311 is crossed by Normal sequence (N), the expected duplication class is viable while the corresponding deficiency is lethal; 44% of the asci have 8 Black (viable) spores and 0 White (inviable) spores, 41% have 4 Black: 4 White, and 10% have 6 Black: 2 White. These are the ascus types expected from normal centromere disjunction without crossing over (8B:0W and 4B:4W equally probable), and with crossing over between centromere and break point (6B:2W). On germination, 8B:0W asci give rise to only parental types—4 T and 4 N; 4B:4W asci usually give four duplication (Dup) progeny; and 6B:2W asci usually give 2 T, 2 N, 2 Dup. Thus one third of all viable, black ascospores contain duplications.—Recessive markers in the donor chromosome which contributes the translocated segment can be mapped by duplication coverage. Ratios of 2 Dominant: 1 Recessive νs. 1 Dominant: 2 Recessive distinguish location in or outside the transposed segment. Eleven loci including mating type have been shown to lie within the segment, and markers at four loci have been transferred into the segment by meiotic recombination. The frequency of marker transfer indicates that the inserted segment usually pairs with its homologue. Ascus types that would result from single exchanges within the insertion are infrequent, as expected if asci containing dicentric bridges usually do not survive.—Duplication ascospores germinate to produce distinctive inhibited colonies. Later these "escape" to grow like wild type, and genes that were initially heterozygous in the duplication segregate when escape occurs. As with duplications from pericentric inversion In(IL⇉IR)H4250 (Newmeyer and Taylor 1967), the initial inhibition is attributed to mating-type heterozygosity, and escape to a somatic event that makes mating type homoor hemizygous.—Twenty additional duplication-generating Neurospora rearrangements are listed and described briefly in an Appendix.
MEIOTIC CHROMOSOME BEHAVIOR OF AN INVERTED INSERTIONAL TRANSLOCATION IN NEUROSPORA
Authors: Barry Edward G 
Published: January 2021

ABSTRACT
Cytological study of meiotic chromosomes heterozygous for the T(I⇉II)39311 translocation confirm genetic evidence (Perkins 1972) that a section of linkage group I including the mating type locus has been inserted into linkage group II. Pachytene chromosomes when fully paired show that a segment from chromosome 1 has been inserted into chromosome 6. When pairing fails between the translocated segment in 6 and its homologous region in chromosome 1, buckles or loops are formed at pachynema in the deletion or insertion areas of the bivalents.—Acentric fragments and anaphase bridges occur at both meiotic divisions and in the subsequent two mitotic divisions in the ascus. These provide supporting evidence that the translocated segment is inverted with respect to centromere in its new location.—Unexpectedly the acentric fragment, formed by crossing over in the inverted translocated segment, persists without degradation in a micronucleus, and it replicates and divides in synchrony with the centric chromosomes in adjacent nuclei.
CARBONIC ANHYDRASE POLYMORPHISM IN A NEW JERSEY POPULATION OF THE WHITE-FOOTED MOUSE PEROMYSCUS LEUCOPUS
Authors: Wilmot Patrick L , Underhill Donald K 
Published: January 2021

ABSTRACT
Two electrophoretic forms of erythrocytic carbonic anhydrase were found to be controlled by one autosomal locus with two codominant alleles, CAf and CA8. The gene frequencies for the CAf and CA8 alleles were found to be.15 and.85, respectively, in a sample of 53 mice from Middlesex County, New Jersey. The observed genotypic frequencies indicated that the population was in Hardy-Weinberg equilibrium.
SPERM PREFERENCE IN DROSOPHILA MELANOGASTER
†
Authors: Childress D , Hartl D L 
Published: January 2021

Abstract
A mating is described in which the females appear actively to discriminate against one of the genotypes of sperm. The males in the mating carry T(1;4)B S , and the sperm type selected against is the B S+4-bearing segregant. Prior exposure of the reproductive tract of the females to B S+4-bearing sperm seems to enhance the ability of the females to subsequently discriminate against B S+4-bearing sperm. Thus it appears that at least some females of Drosophila melanogaster do possess a mechanism whereby different types of sperm can be distinguished—the sperm preference observed in this system appears to be independent of the meiotic drive in the T(1;4)B S males.
POPULATION DYNAMICS OF PURINE AND PYRIMIDINE ANALOG SENSITIVE AND RESISTANT MAMMALIAN CELLS GROWN IN CULTURE1
2
Authors: Morrow John 
Published: January 2021

Abstract
The population dynamics of purine analog resistance have been studied. Two types of reconstruction experiments were performed: cloning numbers of azaguanine resistant, BUdR resistant, and sensitive cells were plated in the presence of a large number of the opposite genotype, which were made to act as a feeder layer by inactivating them with either the appropriate analog or the reverse selective HAT medium. These experiments demonstrate that there is no significant metabolic cooperation between drug resistant and drug sensitive cells, with the exception of BUdR sensitive cells, which at high densities inhibit the cloning ability of BUdR resistant cells in the presence of the drug. Thus the purine analog resistance system can be used for obtaining quantitative data concerning such parameters as mutation and selection, while at high cell densities the pyrimidine analog system appears to be unsatisfactory.——A second series of experiments indicates that, in artificial mixtures of sensitive and resistant cells grown in standard medium, the resistant cells are at a selective disadvantage and will be reduced eventually to the frequency which is observed in wild type populations.
A HISTIDINE OPERATOR-CONSTITUTIVE MUTATION DECREASES THE FREQUENCY OF RECOMBINATION WITHIN THE HISTIDINE OPERON OF SALMONELLA TYPHIMURIUM
Authors: Savic Dragutin J 
Published: January 2021

Abstract
A constitutive mutation in the histidine operon in Salmonella leads to a decrease in the recombinant recovery following transduction with P22 phage. This decrease appears to be a true decrease in recombination within the histidine operon and specific to that gene region. In addition, a strain with an unlinked mutation was isolated in which an operator-constitutive mutation is lethal.
THE T6 TRANSLOCATION IN THE MOUSE: ITS USE IN TRISOMY MAPPING, CENTROMERE LOCALIZATION, AND CYTOLOGICAL IDENTIFICATION OF LINKAGE GROUP III
Authors: Eicher Eva M , Green Margaret C 
Published: January 2021

ABSTRACT
The occurrence of hairless piebald mice trisomic for the chromosome segments of the T6M chromosome has shown that the LG III loci hr and s are not located on T6M. The T6 breakpoint in LG III is therefore in the position hr—s—T6. T6M must carry the gene Fkl, which is located on the far side of the T6 breakpoint from hr in LG III.—T6 reduces recombination in the hr—s region.—Trisomy for the chromosome segments of the T6M chromosome appears to severely reduce viability.—The gene hr has been shown to lie between the centromere and the T6 breakpoint. The order of loci in LG III is therefore: centromere—hr—s—T6.—Equations are given for the relation between the frequency of adjacent-2 segregation and the frequency of recovery of complementation zygotes for the case in which the translocation heterozygote can form either quadrivalent or univalent-trivalent configurations at meiosis.—Linkage Group III is carried on chromosome 14. LG VI is the other linkage group involved in T6, and is carried on chromosome 15.