bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENES AFFECTING THE EXPRESSION OF CYTOCHROME c IN YEAST: GENETIC MAPPING AND GENETIC INTERACTIONS
Authors: Rothstein Rodney J , Sherman Fred 
Published: April 2021

ABSTRACT
The four mutant genes, cyc2, cyc3, cycl and cyc9, that affect the levels of the two iso-cytochromes c in the yeast Saccharomyces cerevisiae have been characterized and mapped. Both cyc2 and cyc3 lower the amount of iso-l-cytochrome c and iso-2-cytochrome c; whereas, cyc8 and cyc9 increase the amount of iso-2-cytochrome c. The cyc2, cyc3, cyc8 and cyc9 genes are located, respectively, on chromosomes XV, I, II and III, and are, therefore, unlinked to each other and unlinked to CYCI, the structural gene of iso-I-cytochrome c and to CYC7, the structural gene of iso-2-cytochrome c. While some cyc3 mutants are completely or almost completely deficient in cyotchromes c, none of the cyc2 mutants contained less than 10% of parental level of cytochrome c even though over one-half of the mutants contain UAA or UAG nonsense mutations. Thus, it appears as if a complete block of the cyc2 gene product still allows the formation of a residual fraction of cytochrome c. The cyc2 and cyc3 mutant genes cause deficiencies even i n the presence of CYC7, cyc8 and cycY, which normally cause overproduction of iso-2-cytochrome c. We suggest that cyc2 and cyc3 may be involved with the regulation or maturation of the iso-cytochromes c. In addition to having high levels of iso-2-cytochromes c, the cyc8 and cyc9 mutants are associated with flocculent cells and other abnormal phenotypes. The cyc9 mutant was shown to be allelic with the tup1 mutant and to share its properties, which include the ability to utilize exogenous dTMP, a characteristic flocculent morphology, the lack of sporulation of homozygous diploids and low frequency of mating and abnormally shaped cells Df a strains. The diverse abnormalities suggest that cyc8 and cyc9 are not simple regulatory mutants controlling iso-2-cytochrome C.
PLEIOTROPIC MUTATIONS AT THE TUP1 LOCUS THAT AFFECT THE EXPRESSION OF MATING-TYPE-DEPENDENT FUNCTIONS IN SACCHAROMYCES CEREVISIAE
Authors: Lemontt Jeffrey F , Fugit Donna R , Mackay Vivian L 
Published: April 2021

ABSTRACT
The umr7-1 mutation, previously identified in a set of mutants that had been selected for defective UV-induced mutagenesis at CAN1, affects other cellular functions, including many of those regulated by the mating-type locus (MAT) in heterothallic Saccharomyces cereuisiae. The recessive umr7-1 allele, mapping approximately 20 cM distal to thr4 on chromosome III, causes clumpy growth in both a and α cells and has no apparent effect on a mating functions. However, α umr7 meiotic segregants fail to express several α-specific functions (e.g., high-frequency conjugation with a strains, secretion of the hormone α-factor and response to the hormone a-factor). In addition, α umr7 cells exhibit some a-specific characteristics, such as the barrier phenotype (Bar+) that prevents diffusion of α-factor and an increased mating frequency with α strains. The most striking property of α umr7 strains is their altered morphology, in which mitotic cells develop an asymmetric pear shape, like that of normal a cells induced to form "shmoos" by interaction with α-factor. Some a/α-specific diploid functions are also affected by umr7; instead ofpolar budding patterns, a/α umr7/umr7 diploids have medial budding like a/a,α/α and haploid strains. Moreover, a/α umr7/umr7 diploids have lost the ability to sporulate and are Bar+ like a or a/a strains. Revertant studies indicate that umr7-1 is a single point mutation. The umr7 mutant fails to complement mutants of both tup1 (selected for deoxythymidine monophosphate utilization) and cyc9 (selected for high iso-2-cytochrome c levels), and all three isolates have similar genetic and phenotypic properties. It is suggested that the product of this gene plays some common central role in the complex regulation of the expression of both MAT-dependent and MAT-independent functions.
CYTOGENETICS OF DISOMICS, MONOTELO- AND MONOISODISOMICS AND ml1 st1 MUTANTS OF CHROMOSOME 4 OF COTTON
Authors: Endrizzi J E , Bray R 
Published: April 2021

ABSTRACT
The linkage relationships and arm locations of the ml1 and st1 mutants of cotton were determined with the use of monotelodisomics, a monoisodisomic and disomics. The ml1, st1 mutants are more than 50 cM apart on chromosome 4. The ml1 locus is in the short arm and 16 cM from the centromere, and st1 is in the long arm and 48 or more CM from the centromere. Recombination in the monoisodisomic was twice the expected value and higher, but not significantly, than in its monotelodisomic counterpart. It was concluded that the increase indicates a greater frequency of proximal exchange in the mono-isodisomic than in the monotelodisomic.
SERIAL-SECTION ANALYSIS OF CLUSTERING WITHIN ANTHERS OF MAIZE MICROSPOROCYTES WITH SPECIFIC CROSSOVERS
Authors: Maguire Majorie P 
Published: April 2021

ABSTRACT
The distribution within anthers of maize plants of microsporocytes of differing crossover class was studied by application of the serial-sectioning technique to plants heterozygous for a paracentric inversion. In such material, cells with four-strand double crossovers within the inversion are distinguishable from cells with other classes of crossovers within the inverted region and from cells with no crossovers within the inversion. Evidence was found for coarse clustering of cells with four-strand double crossovers within the inversion and for coarse clustering of cells of other crossover classes (with at least one crossover within the inversion). The local frequencies of these two major categories of crossover cells appeared to vary independently of each other, with regional increases in each occurring at the expense of noncrossover cells. There is also some suggestion that cells with four-straqd doubles within the inversion may he clustered independently of other double-crossover classes within the inversion, but these other classes are not directly scorable.
RATE OF GENE SILENCING AT DUPLICATE LOCI: A THEORETICAL STUDY AND INTERPRETATION OF DATA FROM TETRAPLOID FISHES
Authors: Li Wen-Hsiung 
Published: April 2021

ABSTRACT
A large-scale simulation has been conducted on the rate of gene loss at duplicate loci under irreversible mutation. It is found that tight linkage does not provide a strong sheltering effect, as thought by previous authors; indeed, the mean loss time for the case of tight linkage is of the same order of magnitude as that for no linkage, as long as Nu is not much larger than 1, where N is the effective population size and u the mutation rate. When Nu is 0.01 or less, the two loci behave almost as neutral loci, regardless of linkage, and the mean loss time is about only half the mean extinction time for a neutral allele under irreversible mutation. However, the former becomes two or more times larger than the latter when Nu ≥ 1.—In the simulation, the sojourn times in the frequency intervals (0, 001) and (0.99, 1) and the time for the frequency of the null allele to reach 0.99 at one of the two loci have also been recorded. The results show that the populatian is monomorphic for the normal allele most of the time if Nu ≤ 0.01, but polymorphic for the null and the normal alleles most of the time if Nu ≥ 0.1.—The distribution of the frequency of the null allele in an equilibrium tetraploid population has been studied analytically. The present results have been applied to interpret data from some fish groups that are of tetraploid origin, and a model for explaining the slow rate of gene loss in these fishes is proposed.
AN ANTISUPPRESSOR THAT ACTS ON OMNIPOTENT SUPPRESSORS IN YEAST
Authors: Liebman Susan W , Cavenagh Margaret 
Published: April 2021

ABSTRACT
Six partially dominant antisuppressors were obtained that reduce the efficiency of two omnipotent yeast suppressors, sup45 and sup35, thought to be ribosomal ambiguity mutations. Each of these six antisuppressors was shown to fall within a single Mendelian locus, named asu9. The mu9 mutations are specific for omnipotent suppressors; they have no effect on several dominant tRNA-like suppressors. In the absence of suppressors, mu9 causes sensitivity to the aminoglycoside antibiotic, paromomycin. The properties of mu9 are consistent with the hypothesis that mu9 alters yeast ribosomal proteins.
CYTOGENETIC ANALYSIS OF THE CHROMOSOMAL REGION IMMEDIATELY ADJACENT TO THE ROSY LOCUS IN DROSOPHILA MELANOGASTER
Authors: Hilliker Arthur J , Clark Stephen H , Chovnick Arthur , Gelbart William M 
Published: April 2021

ABSTRACT
This report describes the genetic analysis of a region of the third chromosome of Drosophila melanogaster extending from 87D2-4 to 87E12-F1, an interval of 23 or 24 polytene chromosome bands. This region includes the rosy (ry, 3-52.0) locus, carrying the structural information for xanthine dehydrogenase (XDH). We have, in recent years, focused attention on the genetic regulation of the rosy locus and, therefore, wished to ascertain in detail the immediate genetic environmcnt of this locus. Specifically, we question if rosy is a solitary genetic unit or part of a larger complex genetic unit encompassing adjacent genes. Our data also provide opportunity to examine further the relationship between euchromatic gene distrihution and polytene chromosome structure.—The results of our genetic dissection of the rosy microregion substantiate the conclusion drawn earlier (SCHALET, KERNAGHAN and CHOVNICK 1964) that the rosy locus is the only gene in this region concerned with XDH activity and that all adjacent genetic units are functionally, as well as spatially, distinct Erom the rosy gene. Within the rosy micro-region, we observed a close correspondence between the number of complementation groups (21) and the number of polytene chromosome bands (23 or 24). Consideration of this latter observation in conjunction with those of similar studies of other chhromosomal regions supports the hypothesis that each polytene chromosome band corresponds to a single genetic unit.
THE SELECTION OF S. CEREVISIAE MUTANTS DEFECTIVE IN THE START EVENT OF CELL DIVISION
Authors: Reed Steven I 
Published: April 2021

ABSTRACT
Thirty-three temperature-sensitive mutations defective in the start event of the cell division cycle of Saccharomyces cereuisiae were isolated and subjected to preliminary characterization. Complementation studies assigned these mutations to four complementation groups, one of which, cdc28, has been described previously. Genetic analysis revealed that these complementation groups define single nuclear genes, unlinked to one another. One of the three newly identified genes, cdc37, has been located in the yeast linkage map on chromosome IV, two meiotic map units distal to hom2.—Each mutation produces stage-specific arrest of cell division at start, the same point where mating pheromone interrupts division. After synchronization at start by incubation at the restrictive temperature, the mutants retain the capacity to enlarge and to conjugate.
ANALYSIS OF THE AUTOSOMAL MUTATION abo AND ITS INTERACTION WITH THE RIBOSOMAL DNA OF DROSOPHILA MELANOGASTER: THE ROLE OF X-CHROMOSOME HETEROCHROMATIN
Authors: Yedvobnick Barry , Krider Hallie M , Levine Bryan I 
Published: April 2021

ABSTRACT
The autosomal recessive, maternal-effect mutation abnormal oocyte (abo: 2-38) preferentially lowers the viability of XO progeny. The severity of the sex-ratio distortion is reduced by duplications of maternal or zygotic heterochromatin chromatin (SANDLER 1970, 1977; PARRY and SANDLER 1974). Utilizing X-chromosome inversions that contain modifications in the quantity and arrangement of the heterochromatic functions, Xhabo and cr +, we have extended our investigations of nbo's influence on XO male recovery and rDNA redundancy (KRIDER,YEDVOBNICK and LEVINE 1979).——XO males bearing In(1)scs1Lsc4R or In(1)wm4Lsc4R are recovered twice as frequently as X chromosomes containing a single Xh region, implying that these inversions possess a duplication of Xhabo. abo mutant females heterozygous for In(1)scs1Lsc4R and wild-type X chromosomes generate XO progeny that do not contain elevated rDNA redundancies. XO males containing In(1)wm4 exhibit male recoveries and rDNA elevations similar to those of males bearing a wild-type X chromosome, when both derive from a common abo/abo mother. Reciprocal crosses between In(1)wm4 and Canton-S males to attached-X abo females show significant, though reduced, sex ratios in the absence of an rDNA effect. The observation that abo can elevate the rDNA redundancy of In(1)wm4, a chromosome that does not compensate, suggests that abo and cr+ functions are not directly related.
EVIDENCE FOR A COMPLEX CLASS OF NONADENYLATED mRNA IN DROSOPHILA
Authors: Zimmerman J Lynn , Fouts David L , Manning Jerry E 
Published: April 2021

ABSTRACT
The amount, by mass, of poly(A+) mRNA present in the polyribosomes of third-instar larvae of Drosophila melanogaster, and the relative contribution of the poly(A+) mRNA to the sequence complexity of total polysomal RNA, has been determined, Selective removal of poly(A+) mRNA from total polysoma1 RNA by use of either oligo-dT-cellulose, or poly (U)-sepharose affinity chromatography, revealed that only 0.15% of the mass of the polysomal RNA was present as poly(A+) mRNA. The present study shows that this RNA hybridized at saturation with 3.3% of the single-copy DNA in the Drosophila genome. After correction for asymmetric transcription and reactability of the DNA, 7.4% of the single-copy DNA in the Drosophila genome is represented in larval poly(A+) mRNA. This corresponds to 6.73 × 1O6 nucleotides of mRNA coding sequences, or approximately 5,384 diverse RNA sequences of average size 1,250 nucleotides. However, total polysomal RNA hybridizes at saturation to 10.9% of the single-copy DNA sequences. After correcting this value for asymmetric transcripti0n and tracer DNA reactability, 24% of the single-copy DNA in Drosophila is represented in total polysomal RNA. This corresponds to 2.18 × 107 nucleotides of RNA coding sequences or 17,440 diverse RNA molecules of size 1,250 nucleotides. This value is 3.2 times greater than that observed for poly(A+) mRNA, and indicates that ≃69% of the polysomal RNA sequence complexity is contributed by n0nadenylated RNA. Furthermore, if the number of different structural genes represented in total polysomal RNA is ≃1.7 × 104, then the number of genes expressed in thirdinstar larvae exceeds the number of chromomeres in Drosophila by about a factor of three. This numerology indicates that the number of chromomeres observed in polytene chromosomes does not reflect the number of structural gene sequences in the Drosophila genome.
A MODIFIED MODEL OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER
Authors: Hiraizumi Yuichiro , Martin Diana W , Eckstrand Irene A 
Published: April 2021

ABSTRACT
Elements of the Segregation Distorter (SD) system of Drosophila melanogaster, Sd and Rsp, were analyzed and the following points were established: (1) The model of multiple alleles at the Rsp s locus proposed by MARTIN and HIRAIZUMI (1979) is supported by our observations. (2) A modifier of SD, tentatively symbolized M(SD), was found close to cn (2R-57.5). (3) Sd heterozygous males were found to show, under certain genotypic condition, almost complete sterility.——Based upon these observations, the following modified model of segregation distortion is proposed: (1) The M(SD) locus produces a multimeric repressor protein that binds to the Rsp locus as a necessary condition for normal spermiogenesis. M(SD) homozygotes produce a repressor M(SD)/M(SD); whereas, a homozygote for its normal allele M+(SD) produces a M+(SD)/M+(SD) repressor. M(SD)/M+(SD) heterzygotes produce a M(SD)/M+(SD) repressor. (2) The Sd locus produces a certain product that, like an inducer in the lactose system of E. coli, tends to bind with the repressor complexed with the Rsp locus. This binding disrupts the repressor-Rsp complex, causing Rsp locus to be turned on. The product of Rsp transcription, in turn, results in sperm dysfunction. (3) Rsp i, an allele of Rsp, has a strong complexing affinity with the repressor such that the Rsp i-repressor complex is "resistant" to the inducing activity of Sd product. Rsp s, on the other hand, has a weaker complexing affinity than that of Rsp i, and the degree of affinity varies among different Rsp s alleles.——A possible extension of the above model is discussed.
THE INFLUENCE OF SEXUAL AND LARVAL SELECTION ON THE MAINTENANCE OF POLYMORPHISM AT THE SEPIA LOCUS IN DROSOPHILA MELANOGASTER
Authors: Anxolabehere D 
Published: April 2021

ABSTRACT
Sexual selection is measured between two strains of Drosophila melanogaster: a wild strain and a strain mutant at the sepia locus. Frequencydependent male mating was found to be successful, whereas the female genotype exerted no influence. The rarer the male genotype becomes, the greater is its mating success. A selection model is built for this behavior characteristic in which selection operates differently in the two sexes. The genetic consequencies of this model upon the maintenance of genetic polymorphism at the sepia locus are compared to experimental data from previous population cage studies. The fit obtained with this sexual selection model is compared to that of the larval selection model previously investigated. A model composed of both sexual and larval components of fitness is presented. The role that each major selection component is expected to play in experimental populations as the gene frequency changes is discussed. Sexual selection leads to an equilibrium level higher than larval selection, and the combined model is very close to the experimental values.
THE DISTRIBUTION OF INDIVIDUAL HETEROZYGOSITY IN NATURAL POPULATIONS
Authors: Mitton Jeffry B , Pierce Benjamin A 
Published: April 2021

ABSTRACT
Estimation of the distribution of the level of individual heterozygosity within natural populations is explored with both Monte-Carlo simulation studies and data from natural populations. Simulations indicate that heterozygosities estimated from as few as a dozen randomly chosen loci may, to some degree, reflect (r = 0.35) heterozygosity determined by 100 independent loci. The shape of the expected distribution of heterozygosity is heavily dependent upon levels of heterozygosity at the loci. Complete genetic data for 12 loci from 997 Fundulus heteroclitus are used to describe the distributions of heterozygosity for different localities, for age classes and for sexes. The distributions deviate from normality. Distributions from different localities are not different, but the distributions are heterogeneous among age classes at one of two localities and are heterogeneous between the sexes.
MALE-SPECIFIC LETHAL MUTATIONS OF DROSOPHILA MELANOGASTER
Authors: Belote John M , Lucchesi John C 
Published: April 2021

ABSTRACT
A total of 7,416 ethyl methanesulfonate (EMS)-treated second chromosomes and 6,212 EMS-treated third chromosomes were screened for sex-specific lethals. Four new recessive male-specific lethal mutations were recovered. When in homozygous condition, each of these mutations kills males during the late larval or early pupal stages, but has no detectable effect in females. One mutant, mlets, is a temperature sensitive allele of maleless, mle (Fukunaga, Tanaka and Oishi 1975), while the other three mutants identify two new loci: male-specific lethal-1 (msl-1) (two alleles) at map position 2-53.3 and male-specific lethal-2 (msl-2) at 2-9.0.——The male-specific lethality associated with these mutants is not related to the sex per se of the mutant flies, since sex-transforming genes fail to interact with these mutations. Moreover, the presence or absence of a Y chromosome in males or females has no influence on the male-specific lethal action of these mutations. Finally, no single region of the X chromosome, when present as a duplication, is sufficient to rescue males from the lethal effects of msl-1 or msl-2. These results suggest that the number of complete X chromosomes determines whether a fly homozygous for a male-specific lethal mutation lives or dies.
ORGANIZATION OF THE CHORION GENES OF BOMBYX MORI, A MULTIGENE FAMILY. III. DETAILED MARKER COMPOSITION OF THREE GENE CLUSTERS
Authors: Goldsmith Marian R , Clermont-Rattner Eileen 
Published: April 2021

ABSTRACT
The chorion patterns produced by progeny from crosses that were used to define the linked gene clusters, Ch 1, Ch 2 and Ch 3 (strain C108 vs. strain Ascoli), were examined by two-dimensional gel electrophoresis (isoelectric focusing vs. SDS/urea). Approximately 60 proteins were assigned to four previously defined chorion classes, A, B, C and Hc, believed to represent the products of related genes, on the basis of size and relative cysteine content. All strain-specific markers showed co-dominance in the F1, indicating the likelihood that they are not products of post-translational modification. Twentyseven Ascoli markers co-segregated in testcross progeny, and none of the resolved proteins showed independent assortment, confirming their linkage to chromosome 2. Two-dimensional screening of recombinants demonstrated that all three clusters contain Class A and B markers; Hc markers have been found only in Ch 1 and Ch 2; whereas, mapped C markers were confined to Ch 3. This indicates that chorion clusters are heterogeneous with respect to the markers they contain.
QUANTITATIVE MEASUREMENT OF THE ABILITY OF DIFFERENT MUTAGENS TO INDUCE AN INHERITED CHANGE IN PHENOTYPE TO ALLOW MALTOSE UTILIZATION IN SUSPENSION CULTURES OF THE SOYBEAN, GLYCINE MAX (L.) MERR
Authors: Weber Gerd , Lark K G 
Published: April 2021

ABSTRACT
Using a newly developed plating system, we have measured cell survival and the frequencies of variation in an inherited trait after treatment of soybean cell suspensions with different mutagens: ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS), N-Methyl-N′-nitro-N-nitroso-guanidine (MNNG), hycanthone (1-{[2-(diethylamino) ethyl] amino}-4-(hydroxymethyl)-9H-thioxanthen-9-one and ultraviolet light (UV).—The heritable variation selected for displays a phenotype of rapid growth on maltose as carbon source. The marker is stable in the absence of maltose, and prolonged growth of variant cells on sucrose has not shown reversions to slow growth. Doubling time in suspension cultures is decreased from 100 hr to ca. 30 hr by the mutation. Both wild-type and variant cells grow on sucrose with a 24-hr doubling time. Thus, lethality after mutagen treatment can be estimated rapidly by growth on sucrose, whereas variants are scored on maltose medium. The spontaneous frequency of variants was 1.2 × 10-7; induced frequencies ranged from a low of 3.6 × 10-5 for EMS to a high of 10-3 for hycanthone. The high frequency of variants induced by hycanthone, a frame-shift mutagen, and the observation that UV induces variants in haploid cells with much higher frequency than in diploid cells suggests a recessive mutation.