bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENETIC VARIATION AT A LOCUS (TAM-1) FOR SUBMAXILLARY GLAND PROTEASE IN THE MOUSE AND ITS LOCATION ON CHROMOSOME 7
Authors: Skow Loren C 
Published: April 2021

ABSTRACT
Electrophoretic and activity variants for a testosterone-induced esteroprotease have been discovered in submaxillary glands from inbred strains of mice. The enzyme is tentatively designated tamase (TAM-1) and the variant genetic locus is Tam-1. The alleles Tam-1a and Tam-1b determine electrophoretically distinct zones of tamase activity, while Tam-1c produces no detectable enzyme activity. Data from recombinant inbred strains and B6AF1 x B6 and B6D2F1 x B6 backcrosses established linkage of Tam-1 to glucose phosphate isomerase (Gpi-1), pink-eyed dilution (p) and β-hemoglobin (Hbb) on chromosome 7. The gene order is Gpi-1—Tam-1—p—Hbb. Analysis of congenic resistant strains indicates that Tam-1 is closely linked to the minor histocompatibility locus, H-4. TAM-1 was not cross-reactive with antisera to mouse nerve growth factor, submaxillary renin, or tamases A and D.
POSITION EFFECTS AT THE HAIRY LOCUS IN DROSOPHILA MELANOGASTER
Authors: Jeffery Duane E 
Published: April 2021

ABSTRACT
Radiation-induced chromosomal rearrangements of h+ have given rise to several Drosophila stocks that exhibit apparent position-effect inactivation; i.e., flies carrying the rearranged chromosomes heterozygously with h show varying degrees of hairiness. The numbers of hairy chaetae produce a quantifiable index of position effect. Six such "position-allele'' stocks are here discussed, both as to their basic expressions and in all possible pair-wise combinations with each other. Such crosses reveal complex interactions between the respective position alleles; little evidence is seen for clear-cut dominance or recessiveness. The stocks appear not to conform unequivocally to classical distinctions between variegated and stable types of position effects, nor to usual dicta relating the degree of inactivity to the proximity to heterochromatin. Indeed, these stocks appear to suggest additional dimensions to several of the principles to which position effects usually subscribe. The evidence additionally suggests that the hairy locus itself is associated with a tissue-specific suppressor effect on an otherwise polygenic system that produces the chaetae associated with the hairy phenotype.
GENETIC ANALYSIS OF MULTIPLE DRUG CROSS RESISTANCE IN SACCHAROMYCES CEREVISIAE: A NUCLEAR-MITOCHONDRIAL GENE INTERACTION
Authors: Cohen Joe D , Eaton Norman R 
Published: April 2021

ABSTRACT
A mutant of the yeast Saccharomyces cereuisiae, cross resistant to several antibiotics, was isolated in our laboratory and subjected to genetic analysis. Tetrad analysis of diploids obtained from crosses between the resistant mutant and a sensitive wild-type strain suggest that the multiple resistance to the five agents, oligomycin (OLI), rhodamine 6G (RHG), tetracycline (TCN), chloramphenicol (CAP) and cycloheximide (CHX) is determined by a single nuclear gene, anti, and requires several cytoplasmic genes for expression of resistance to oligomycin, rhodamine 6G and tetracycline.——Vegetatively growing diploid clones derived from the cross ant1 [RHO+] × + [RHO+] show mitotic segregation of two phenotypic classes for the drugs OLI, RHG TCN. Diploids derived from the two reciprocal crosses, ant1 [RHO+] × + [RHO-] and ant1 [RHO-] × + [RHO+], fail to exhibit mitotic segregation. These results are consistent with our hypothesis concerning the involvement of cytoplasmic loci. They suggest, in addition, that these loci are associated with mitochondrial DNA (mtDNA) .——Evidence for this association is provided by the demonstration of genetic linkage between the cytoplasmic loci involved in the interaction, RHG-1, TCN-1 and OLI-5, and two well-characterized mitochondrial loci, ERY and CAP.——We have mapped the nuclear ant1 locus 3.3 cM from the centromere-linked gene, leu1, on the same side of the centromere of chromosome VII as leu1.——In the light of these findings, we discuss the claims made by several authors of the episomal nature of mutations similar ta the one described here, as well as of the possible involvement of yeast 2μ DNA in such mutations.
ESTIMATION OF FITNESS COMPONENTS IN DROSOPHILA MELANOGASTER. II. INFLUENCE OF REDUCED TRANSMISSION FREQUENCY
Authors: Katz Alan J 
Published: April 2021

ABSTRACT
Results are presented of further analyses of the significant effects of reciprocal crosses reported by KATZ and CARDELLINO(1978) in regard to viability indices of wild-type second chromosome heterozygotes. The observed differences between reciprocal crosses can be explained by the existence of reduced transmission frequencies of the wild-type homologue from Pm/+ and Cy/+ paternal parents. Mean estimates of transmission frequencies from Pm/+ and cy/+ males in California and Japan populations are significantly less than the Mendelian expectation of 1/2. The transmission frequencies of +i chromosomes from Pm/+i and Cy/+i males are also found to be positively correlated in the California and pooled populations, suggesting that the degree of distortion is primarily due to the +i chromosome rather than to Cy or Pm. A sufficient estimator of relative viability that is independent of distorted transmission frequencies is derived for use in the Cy/Pm technique of viability estimation.
TRANSFER OF DRUG RESISTANCE FACTORS TO THE DIMORPHIC BACTERIUM CAULOBACTER CRESCENTUS
Authors: Ely Bert 
Published: April 2021

ABSTRACT
The P-type drug resistance factors RP4, RK2, R702, R68.45, and the N-type drug resistance factor R46 are transferred to Caulobacter crescentus at high frequencies. They are stably maintained and their antibiotic resistances are expressed. Experiments with RP4 have shown that intergeneric transfer of RP4 occurs with greater than 90% of the recipient cells in filter matings between Escherichia coli donors and C. crescentus recipients. Reciprocal matings with C. crescentus donors are less efficient, but still occur at a frequency of 10-1. C. crescentus strains maintain RP4 as a plasmid, are sensitive to RP4 specific phage, and segregate phage-resistant cells at a frequency of 10-4 to 10-5. The RP4 plasmid can be used in several ways: (1) the RP4 plasmid will promote chromosomal exchange between C. crescentus strains at frequencies ranging from 10-6 to 10-8; (2) RP4 will promote the transfer of nonconjugative colEl plasmids from E. coli to C. crescentus; once transferred, the colEl plasmid is stably maintained under nonselective conditions, can be transferred serially, and segregates independently from RP4; and (3) RP4 can be used to introduce transposons into the C. crescentus chromosome, providing the basis for additional genetic techniques.
COMPLEMENTATION OF AMOEBAL-PLASMODIAL TRANSITION MUTANTS IN PHYSARUM POLYCEPHALUM
Authors: Anderson Roger W 
Published: April 2021

ABSTRACT
Amoebae of the Myxomycete Physarum polycephalum differentiate to yield plasmodia in two ways: in crossing, haploid amoebae of appropriate genotypes fuse to form diploid plasmodia; in selfing, plasmodia form without amoebal fusion or increase in ploidy. Amoebae carrying the mating-type allele matAh (formerly mth) self efficiently, but occasionally give rise to mutants that self at very low frequencies. Such "amoebal-plasmodial transition" mutants were mixed in pairs to test their ability to complement one another in the formation of plasmodia by crossing. The pattern of crossing permitted 33 mutants to be assigned to four complementation groups (aptA-, npfA-, npfB- and npfC-). Similar tests had previously proved only partially successful, as crossing had occurred only rarely in mixtures of compatible strains. The efficiency of complementation was greatly increased in the current work by mixing strains that carried different alleles of a newly-discovered mating-compatibility locus, matB; this locus had no effect on the specificity of complementation. A possible interpretation of the complementation behavior of the mutants is suggested.
A MUTATIONAL ANALYSIS OF THE TRIPLO-LETHAL REGION OF DROSOPHILA MELANOGASTER
Authors: Keppy D O , Denell R E 
Published: April 2021

ABSTRACT
The extensive analysis of the impact of segmental aneuploidy by LINDSLEY et al. (1972) showed that there are relatively few haplo-lethal loci in the genome and that, with one exception, all loci are triplo-viable. The exceptional locus, which lies in salivary gland chromosome region 83D-E, is associated with lethality when present in either one or three doses in an otherwise diploid individual (DENEU 1976). The genetic nature of the phenomenon has been studied by examining the rates of induction, by ionizing radiation and chemical mutagens, of mutations affecting the dose-sensitive behavior. For both types of mutagens, the frequency of inactivation of the locus is relatively low, and a high proportion of such mutations is associated with chromosomal deficiencies. These data indicate that the locus is infrequently and perhaps never inactivated by a DNA base-pair substitution and thus that the triplo-lethal phenomenon is not associated with a "typical" structural gene. It is possible that the triplo-lethal locus is very small, is reiterated or otherwise complex or is functionally insensitive to base-pair substitutions. The result that all mutations that complement a duplication of the triplo-lethal locus are lethal in heterozygous combination with a normal third chromosome argues that triplo- and haplo-lethality are concomitants of the same phenomenon. Salivary gland chromosome analysis of newly induced deficiencies and duplications localizes the locus to 83D4,5-83E1,2, and further cytogenetic manipulation shows that the dose-sensitive behavior is independent of the position of the locus in the genome.
VIABILITY OF HOMOZYGOUS DEFICIENCIES IN SOMATIC CELLS OF DROSOPHILA MELANOGASTER
Authors: Ripoll Pedro , García-Bellido A 
Published: April 2021

ABSTRACT
The viability of cells made homozygous for different deficiencies by induced mitotic recombination was examined. The deficiencies varied in length from two to 30 polytene chromosome bands and were distributed over the five major chromosome arms. Among a sample of 30, ten deficiencies were cell viable. Our results show that 12% of the genome is necessary for cell survival, supporting previous estimates of about 5,000 genes in the genome of Drosophila.
Hfr FORMATION DIRECTED BY Tn10
Authors: Chumley Forrest G , Menzel Rolf , Roth John R 
Published: April 2021

ABSTRACT
The transposable drug-resistance element, TnlO, can serve as a region of homology to direct the insertion of an F′tsll4 lac plasmid into the chromosome of Salmonella typhimurium. Derivatives of F′tsl14 lac were constructed that carry TnlO insertions; these plasmids were transferred to strains having a TnlO insertion in the chromosome. Under these circumstances, Hfr formation requires homologous recombination between plasmid-borne and Chromosomal TnlO elements. The process is dependent on recA function and on the presence of both TnlO elements. All Hfr's isolated from a given merodiploid show the same direction of transfer. Depending on the orientation of TnlO in the F′ plasmid, Hfr's transferring in either direction can be obtained from any chromosomal TnlO insertion. Since TnlO insertions can be generated in any region of the chromosome, this method permits the isolation of Hfr's with either direction of transfer having their origin at almost any predetermined site. The Hfr's constructed by this method are sufficiently stable for standard genetic mapping crosses, and they have also been used to generate new F′ plasmids. Implicit in the results above is the possibility of determining the orientation of any chromosomal TnlO insertion by constructing an Hfr using a standard F′ TnlO plasmid and determining the direction of chromosome transfer. The general approaches described here are applicable to other transposable elements and other bacterial systems.
GENETIC VARIABILITY AND DIVERGENCE IN GRAYLING, THYMALLUS ARCTICUS
Authors: Lynch J C , Vyse E R 
Published: April 2021

ABSTRACT
In North America there are two disjunct forms of grayling, Montana and arctic, which have been separated for approximately 75,000 to 100,000 years. Electrophoretic analysis of thirty-six protein loci in these forms has revealed: (1) levels of gene duplication comparable to other salmonids, (2) a level of heterozygosity similar to other salmonids, (3) a fast and a slow evolving set of proteins, and (4) no obvious relationship between genetic variability and enzyme function. The genetic divergence between these populations may warrant subspecific designations for these two forms.
ORGANIZATION OF THE qa GENE CLUSTER IN NEUROSPORA CRASSA: DIRECTION OF TRANSCRIPTION OF THE qa-3 GENE
Authors: Strøman Per , Reinert William , Case Mary E , Giles Norman H 
Published: April 2021

ABSTRACT
In Neurospora crassa, the enzyme quinate (shikimate) dehydrogenase catalyzes the first reaction in the inducible quinic acid catabolic pathway and is encoded in the qa-3 gene of the qa cluster. In this cluster, the order of genes has been established as qa-I qa-3 qa-4 qa-2. Amino-terminal sequences have been determined for purified quinate dehydrogenase from wild type and from UV-induced revertants in two different qa-3 mutants. These two mutants (M16 and M45) map at opposite ends of the qa-3 locus. In addition, mapping data (CASE et al. 1978) indicate that the end of the qa-3 gene specified by M45 is closer to the adjacent qa-1 gene than is the end specified by the MI6 mutant site. In one of the revertants (R46 from qa-3 mutant M45), the amino-terminal sequence for the first ten amino acids is identical to that of wild type. The other revertant (R1 from qa-3 mutant M16) differs from wild type at the amino-terminal end by a single altered residue at position three in the sequence. The observed change involves the substitution of an isoleucine in M16-Rl for a proline in wild type. This substitution requires a two-nucleotide change in the corresponding wild-type codon.——The combined genetic and biochemical data indicate that the qa-3 mutants M16 and M45 carry amino acid substitutions near the amino-terminal and carboxyl-terminal ends of the quinate dehydrogenase enzyme, respectively. On this basis we conclude that transcription of the qa-3 gene proceeds from the end specified by the MI6 mutant site in the direction of the qa-1 gene. It appears probable that transcription is initiated from a promoter site within the qa cluster, possibly immediately adjacent to the qa-3 gene.
THE GENETICS OF A PROBABLE INSERTIONAL TRANSLOCATION IN SORDARIA BREVICOLLIS
Authors: Bond D J 
Published: April 2021

ABSTRACT
A chromosome rearrangement has been isolated and characterized in Sorduria brevicollis. Crosses to spore color mutants on each of the seven linkage groups have enabled the breakpoints to be mapped. The simplest hypothesis to account for the results is that a piece of linkage group VI has been trans-located to linkage group V and inserted 2.7 map units from its centromere. Previous reports of markers on this linkage group with centromere distances greater than 2.7 units make it unlikely that the translocation is quasiterminal.
A CLUSTER OF THREE GENES RESPONSIBLE FOR ALLANTOIN DEGRADATION IN SACCHAROMYCES CEREVISIAE
Authors: Cooper Terrance G , Gorski Mary , Turoscy Vanessa 
Published: April 2021

ABSTRACT
Mutant strains of Saccharomyces cerevisiae unable to utilize allantoin as sole nitrogen murce were isolated and divided into three groups on the basis of their biochemical and genetic characteristics. The three loci associated with these mutant classes were designated dall (allantoinase minus), da12 (allantoicase minus) and da14 (allantoin transport minus). All three loci are located in a cluster that is proximal to the lysl locus on the right arm of chromosome IX. The gene order and intergenic distances were estimated to be: dall—2.5 cM—dal4—1.9cM—dal2—4.6cM—lysl.
MUTATION RATES, POPULATION SIZES AND AMOUNTS OF ELECTROPHORETIC VARIATION OF ENZYME LOCI IN NATURAL POPULATIONS
Authors: Zouros E 
Published: April 2021

ABSTRACT
A method is presented for estimating relative mutation rates or relative effective population sizes, under the hypothesis of adaptively neutral allelic variation. This method was applied to seven surveys of electrophoretic variation. It was observed that electrophoretic mutation rates so obtained follow the gamma distribution and, in Drosophila, are positively correlated with the molecular weights of the enzyme subunits. The variance in mutation rate is larger under the step-wise model of electrophoretic mutation than under the infinite-alleles model. Rates for the most variable loci may exceed rates for less variable loci by a factor of 500. For completely invariant loci, this factor may be as high as 4 × 104, an observation suggesting that these loci are subject to purifying selection. In contrast to mutation rates, effective population sizes may vary at the most by a factor of ten. These results support the hypothesis that differences in the amount of electrophoretic variability among polymorphic loci may reflect differences in the rate by which electrophoretically detectable variation is generated in populations.
MAINTENANCE OF GENETIC VARIABILITY UNDER THE PRESSURE OF NEUTRAL AND DELETERIOUS MUTATIONS IN A FINITE POPULATION
Authors: Li Wen-Hsiung 
Published: April 2021

ABSTRACT
In order to assess the effect of deleterious mutations on various measures of genic variation, approximate formulas have been developed for the frequency spectrum, the mean number of alleles in a sample, and the mean homozy-gosity; in some particular cases, exact formulas have been obtained. The assumptions made are that two classes of mutations exist, neutral and deleterious, and that selection is strong enough to keep deleterious alleles in low frequencies, the mode of selection being either genic or recessive. The main findings are: (1) If the expected value () of the sum of the frequencies of deleterious alleles is about 10% or less, then the presence of deleterious alleles causes only a minor reduction in the mean number of neutral alleles ir, a sample, as compared to the case of = 0. Also, the low- and intermediate-frequency parts of the frequency spectrum of neutral alleles are little affected by the presence of deleterious alleles, though the high-frequency part may be changed drastically. (2) The contribution of deleterious mutations to the expected total number of alleles in a sample can be quite large even if is only 1 or 2%. (3) The mean homozygosity is roughly equal to (1-2)/(1+λ 1), where λ 1, is twice the number of new neutral mutations occurring in each generation in the total population. Thus, deleterious mutations increase the mean heterozygosity by about 2/ (1 +λ 1). The present results have been applied to study the controversial problem of how deleterious mutations may affect the testing of the neutral mutation hypothesis.
REGIONAL SPECIFICITY OF ILLEGITIMATE RECOMBINATION BY THE TRANSLOCATABLE AMPLICILLIN-RESISTANCE ELEMENT Tn1 IN THE GENOME OF PHAGE P22
Authors: Weinstock George M , Susskind Miriam M , Botstein David 
Published: April 2021

ABSTRACT
Insertions of the translocatable ampicillin-resistance element Tnl were selected in the genome of the temperate Salmonella phage P22 by growing the phage on hosts carrying the resistance plasmid RP4. Insertions of Tnl into phage P22 are rare (10-10 per phage) and nonrandomly distributed in the P22 genome. They are found mainly in the vicinity of the P22 ant gene. Insertions within the ant gene are found at many (at least 15) genetically separable sites, are found equally frequently in both orientations and cause irreversible loss of gene function. Some insertions in ant appear to be associated with an adjecent deletion.—Prophage deletions were derived from P22::Tnl phages by two methods. Low multiplicity transductants have nonrandomly distributed endpoints. One end is at or very near the site of the Tnl insertion, and the other is in the vicinity of gene 12; however, there are many genetically distinguishable endpoints within gene 12. Prophage deletions selected as survivors of induction of a P22Ap mnt-ts lysogen have similarly nonrandom endpoints, with the Tnl-distal end frequently near the ant gene, as well as gene 12. Physical analysis of several prophage deletions suggests that the Tnl is intact to the resolution of DNA electron microscopy and that the deletions begin at the end of the Tnl insertion.—These results suggest that illegitimate recombination associated with Tnl shows regional specificity (i.e., preference for some large areas of the P22 genome over other areas), but that within these regions is quite nonspecific.
FREQUENCY-DEPENDENT SELECTION AT THE PGM-1 LOCUS OF DROSOPHILA PSEUDOOBSCURA
Authors: Snyder Thomas P , Ayala Francisco J 
Published: April 2021

ABSTRACT
Frequency-dependent fitness was studied at the Pgm-1 locus of Drosophila pseudoobscura with respect to two fitness components: rate of development and larva-to-adult survival. The Pgm-1 locus is very polyniorphic with only two alleles, Pgm-1100 and Pgm-1104, occurring at high frequencies. For each of these two alleles, 20 homozygous strains were obtained from a sample of 1,140 wild-inseminated females. First-instar larvae of the two genotypes were combined in a set of eight different frequencies: 0.0, 0.10, 0.95, 0.40, 0.60, 0.75, 0.90, and 1.0. Frequency-dependent fitness effects were observed for the two survival-related fitness components examined: larvae of the less common genotype develop faster and have a higher probability of survival than larvae of the more common genotype. The rate of survival at intermediate genotypic frequencies is similar to that in pure cultures. If selection acted solely as frequency-dependent effects on survival-related components of fitness, the equilibrium frequency of the Pgm-1100 allele would be 0.615 for a two-genotype system, which fits an observed frequency range for this allele in nature between 0.55 and 0.71. Experimentally created linkage disequilibrium was excluded from the experiment by using a large number of independent strains. It is nevertheless possible that the frequency-dependent selection may not affect the Pgm-1 locus per se, but may reflect a linkage disequilibrium present in the natural population. Even if this were the case, the frequencydependent selection could affect the frequency of the Pgm-1 alleles in nature.
INTRAGENIC SUPPRESSION AT THE b2 LOCUS IN ASCOBOLUS IMMERSUS. II. CHARACTERISTICS OF THE MUTATIONS IN GROUPS A AND E
Authors: Leblon G 
Published: April 2021

ABSTRACT
The present report is a study of GO intragenic suppressors located in the A or E group of the b2 spore-color locus of Ascobolus immersus. The frame-shift nature of the suppressors was shown by 19 combinations of plus and minus suppressor mutations. The location of the mutation sites on the genetic map of group A was defined. The conversion pattern ofi the frameshift suppressors is discussed according to their plus or minus phase shift and their mutagenic origin.