bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vivo Analysis of Folate Coenzymes and Their Compartmentation in Saccharomyces cerevisiae
Authors: McNeil J Bryan , Bognar Andrew L , Pearlman Ronald E 
Published: January 2021

Abstract
In eukaryotes, enzymes responsible for the interconversion of one-carbon units exist in parallel in both mitochondria and the cytoplasm. Strains of Saccharomyces cerevisiae were constructed that possess combinations of gene disruptions at the SHM1 [mitochondrial serine hydroxymethyltransferase (SHMTm)], SHM2 [cytoplasmic SHMT (SHMTc)], MIS1 [mitochondrial C1-tetrahydrofolate synthase (C1-THFSm)], ADE3 [cytoplasmic C1-THF synthase (C1-THFSc)], GCV1 [glycine cleavage system (GCV) protein T], and the GLY1 (involved in glycine synthesis) loci. Analysis of the in vivo growth characteristics and phenotypes was used to determine the contribution to cytoplasmic nucleic acid and amino acid anabolism by the mitochondrial enzymes involved in the interconversion of folate coenzymes. The data indicate that mitochondria transport formate to the cytoplasmic compartment and mitochondrial synthesis of formate appears to rely primarily on SHMTm rather than the glycine cleavage system. The glycine cleavage system and SHMTm cooperate to specifically synthesize serine. With the inactivation of SHM1, however, the glycine cleavage system can make an observable contribution to the level of mitochondrial formate. Inactivation of SHM1, SHM2 and ADE3 is required to render yeast auxotrophic for TMP and methionine, suggesting that TMP synthesized in mitochondria may be available to the cytoplasmic compartment.
New Mutants of Saccharomyces cerevisiae Affected in the Transport of Proteins From the Endoplasmic Reticulum to the Golgi Complex
Authors: Wuestehube Linda J , Duden Rainer , Eun Arlene , Hamamoto Susan , Korn Paul , Ram Rachna , Schekman Randy 
Published: January 2021

Abstract
We have isolated new temperature-sensitive mutations in five complementation groups, sec31-sec35, that are defective in the transport of proteins from the endoplasmic reticulum (ER) to the Golgi complex. The sec31-sec35 mutants and additional alleles of previously identified sec and vacuolar protein sorting (vps) genes were isolated in a screen based on the detection of α-factor precursor in yeast colonies replicated to and lysed on nitrocellulose filters. Secretory protein precursors accumulated in sec31-sec35 mutants at the nonpermissive temperature were core-glycosylated but lacked outer chain carbohydrate, indicating that transport was blocked after translocation into the ER but before arrival in the Golgi complex. Electron microscopy revealed that the newly identified sec mutants accumulated vesicles and membrane structures reminiscent of secretory pathway organelles. Complementation analysis revealed that sec32-1 is an allele of BOS1, a gene implicated in vesicle targeting to the Golgi complex, and sec33-1 is an allele of RET1, a gene that encodes the α subunit of coatomer.
Gametophyte Genetics in Zeu mays L.: Dominance of a Restoration-of-Fertility Allele (Rf3) in Diploid Pollen
Authors: Kamps T L , McCarty D R , Chase C D 
Published: January 2021

Abstract
In Zea mays L. plants carrying the S-type of sterility-inducing cytoplasm, male fertility is determined by a gametophytic, nuclear restoration-of-fertility gene. Haploid pollen carrying the fertility-restoring allele (historically designated Rf3) is starch-filled and functional, whereas pollen carrying the nonrestoring allele (historically designated rf3) is shrunken and nonfunctional. Because restoration of fertility occurs in haploid tissue, the dominance relationship of restoring and nonrestoring alleles is unknown. We have tested the dominance relationship of the restoring and nonrestoring alleles at the rf3 locus in diploid pollen. The meiotic mutant elongate was used to generate tetraploid plants carrying both Rf3 and rf3 alleles in the S cytoplasm. These plants shed predominantly starch-filled pollen, consistent with dominance of the restoring allele. Restriction fragment length polymorphisms linked to the rf3 locus demonstrated cotransmission of rf3 and Rf3 alleles through heterozygous diploid pollen, providing conclusive genetic evidence that the restoring allele is the dominant or functional form of this restoration-of-fertility gene. We suggest that other Scytoplasm restorers result from loss-of-function mutations and propose analysis of unreduced gametes as a test of this model.
Sexual Reproduction Plays a Major Role in the Genetic Structure of Populations of the Fungus Mycosphaerella graminicola
Authors: Chen Ruey-Shyang , McDonald Bruce A 
Published: January 2021

Abstract
The relative contributions of sexual and asexual reproduction to the genetic structure of populations can be difficult to determine for fungi that use a mixture of both types of propagation. Nuclear RFLPs and DNA fingerprints were used to make indirect and direct measures of departures from random mating in a population of the plant pathogenic fungus Mycosphaerella graminicola during the course of an epidemic cycle. DNA fingerprints resolved 617 different genotypes among 673 isolates sampled from a single field over a 3-month period. Only 7% of the isolates represented asexual clones that were found more than once in the sample. The most common clone was found four times. Genotypic diversity averaged 85% of its maximum possible value during the course of the epidemic. Analyses of multilocus structure showed that allelic distributions among RFLP loci were independent. Pairwise comparisons between individual RFLP loci showed that the majority of alleles at these loci were in gametic equilibrium. Though this fungus has the capacity for a significant level of asexual reproduction, each analysis suggested that M. graminicola populations maintain a genetic structure more consistent with random-mating over the course of an epidemic cycle.
Genetic Interactions Between REG1/HEX2 and GLC7, the Gene Encoding the Protein Phosphatase Type 1 Catalytic Subunit in Saccharomyces cerevisiae
Authors: Huang Dongqing , Chun Kristin T , Goebl Mark G , Roach Peter J 
Published: January 2021

Abstract
Mutations in GLC7, the gene encoding the type 1 protein phosphatase catalytic subunit, cause a variety of abberrant phenotypes in yeast, such as impaired glycogen synthesis and relief of glucose repression of the expression of some genes. Loss of function of the REG1/HEX2 gene, necessary for glucose repression of several genes, was found to suppress the glycogendeficient phenotype of the glc7-1 allele. Deletion of REG1 in a wild-type background led to overaccumulation of glycogen as well as slow growth and an enlarged cell size. However, loss of REG1 did not suppress other phenotypes associated with GLC7 mutations, such as inability to sporulate or, in cells bearing the glc7Y-170 allele, lack of growth at 14°. The effect of REG1 deletion on glycogen accumulation is not simply due to derepression of glucose-repressed genes, although it does require the presence of SAF1, which encodes a protein kinase essential for expression of glucose-repressed genes and for glycogen accumulation. We propose that REG1 has a role in controlling glycogen accumulation.
Gene Conversion Alone Accounts for More Than 90% of Recombination Events at the am Locus of Neurospora crassa
Authors: Bowring Frederick J , Catcheside David E A 
Published: January 2021

Abstract
We have used closely flanking molecular markers located ~4 kb distal and 6 kb proximal of the am locus to investigate the incidence of crossover events associated with the generation of prototrophic recombinants in a cross heteroallelic am1 am6. Ninety-three percent of prototrophs were generated by events that did not recombine the molecular markers, indicating that simple conversion accounts for the formation of most prototrophs and that associated crossovers are much less frequent (~0.07) than estimated previously using more distant flanking markers. This suggests that conversion and crossing over during meiosis may arise from distinct mechanisms or that if, as is widely supposed, conversion and crossing over result from alternate modes of resolution of Holliday junctions then, at least for the am locus of Neurospora, the mode of resolution is strongly biased in favor of retaining the parental association of flanking sequences. Because estimates of the association of conversion and crossing over based on more distant gene markers are similar for yeast and Neurospora (~0.35), our observation may have general significance.
A Mendelian Mutation Affecting Mating-Type Determination Also Affects Developmental Genomic Rearrangements in Paramecium tetraurelita
Authors: Meyer Eric , Keller Anne-Marie 
Published: January 2021

Abstract
In Paramecium tetraurelia, mating type is determined during the differentiation of the somatic macronucleus from a zygotic nucleus genetically competent for both types, O and E. Determination of the developing macronucleus is controlled by the parental macronucleus through an unknown mechanism resulting in the maternal inheritance of mating types. The pleiotropic mutation mtFE affects macronuclear differentiation. Determination for E is constitutive in mutant homozygotes; a number of unrelated mutant characters are also acquired during development. We have examined the possibility that the mutation causes a defect in the developmental rearrangements of the germ-line genome. We show that the excision of an IES (internal eliminated sequence) interrupting the coding sequence of a surface antigen gene is impaired in the mutant, resulting in an alternative macronuclear version of the gene. Once established, the excision defect is indefinitely transmitted across sexual generations in the cytoplasmic lineage, even in a wild-type genetic context. Thus, the processes of mating-type determination and excision of this IES, in addition to their common sensitivity to the mtFE mutation, show a similar maternal inheritance of developmental alternatives in wild-type cells, suggesting a molecular model for mating-type determination.
Germline Transformation of Drosophila virilis With the Transposable Element mariner
Authors: Lohe Allan R , Hartl Daniel L 
Published: January 2021

Abstract
An important goal in molecular genetics has been to identify a transposable element that might serve as an efficient transformation vector in diverse species of insects. The transposable element mariner occurs naturally in a wide variety of insects. Although virtually all mariner elements are nonfunctional, the Mosl element isolated from Drosophila mauritiana is functional. Mosl was injected into the pole-cell region of embryos of D. virilis, which last shared a common ancestor with D. mauritiana 40 million years ago. Mosl PCR fragments were detected in several pools of DNA from progeny of injected animals, and backcross lines were established. Because Go lines were pooled, possibly only one transformation event was actually obtained, yielding a minimum frequency of 4%. Mosl segregated in a Mendelian fashion, demonstrating chromosomal integration. The copy number increased by spontaneous mobilization. In situ hybridization confirmed multiple polymorphic locations of Mosl. Integration results in a characteristic 2-bp TA duplication. One Mosl element integrated into a tandem array of 370-bp repeats. Some copies may have integrated into heterochromatin, as evidenced by their ability to support PCR amplification despite absence of a signal in Southern and in situ hybridizations.
Amino Acid Polymorphism and Rare Electrophoretic Variants of G6PD From Natural Populations of Drosophila melanogaster
Authors: Eanes Walter F , Kirchner Michele , Taub Daniel R , Yoon Jeanne , Chen Jiang-tian 
Published: January 2021

Abstract
Identifing the amino acid changes responsible for electrophoretic variants is essential to understanding the significance of allozyme polymorphism in adaptation. The amino acid mutations responsible for the common G6PD allozyme polymorphisms in Drosophila melanogaster have been recently described. This study characterizes the amino acid changes associated with 11 rare electrophoretic G6PD variants. The 11 rare electrophoretic variants result from six independent amino acid mutations. The in vivo function of the rare variants was determined in an earlier study and most variants fell into one of two function classes. It is shown here that the function of the rare variants reflects the state of the Pro/Leu mutation responsible for the A / B allozyme polymorphism in each variant. Two mutations destabilize quaternary structure resulting in shifts from tetrameric to dimeric alleles, and one of these also results in a variant with in vivo function intermediate to A and B. That mutation is an aspartic-acid-to-asparagine change that is two residues away from the Pro/Leu polymorphism responsible for the A / B dimertetramer quaternary shift. Structure-function relationships based on studies of human G6PD deficency-associated mutations predict that these last two amino acid changes fall within the protein domain responsible for NADP-binding.
Mosaic Analysis of the Liguleless3 Mutant Phenotype in Maize by Coordinate Suppression of Mutator-insertion Alleles
Authors: Fowler John E , Muehlbauer Gary J , Freeling Michael 
Published: January 2021

Abstract
Ligubless3-O (Lg3-O) transforms the leaf blade, auricle and ligule into sheath around the midrib region. We conducted a genetic mosaic analysis of the Lg3 phenotype to determine the site of Lg3 gene action. Combining the Mutator (Mu) suppressible Lg3-Or211 and al-mum2 alleles in a Mu-active background generated a stock wherein somatic loss of Mu activity resulted in anthocyanin-marked clonal sectors expressing Lg3 in the leaf. Lg3-Or211 plants appear wild type in a Mu-active line, but Mu-inactive plants express a severe Lg3 phenotype. We observed four sector classes: wild type, sheath-like with ligule displacement, sheath-like with ectopic ligule, and auricle-like. The mutation does not cause transformation to a specific cell or regional identity. Lg3-Or211 activity in the mesophyll alters wild-type epidermal cell fates; activity in epidermis seems funtionless. Lg3 mutant activity has a nonautonomous, cell-layer-specific function in the transverse dimension. In the lateral dimension, sectors of Lg3 mutant phenotype can exhibit either cell-autonomous or nonautonomous effects. Our work demonstrates that mosaic analysis by coordinate suppression of Mu-induced alleles is useful for analyzing the cell autonomy of genetically defined functions.
Deletion of the Gene Encoding the Cyclin-Dependent Protein Kinase Pho85 Alters Glycogen Metabolism in Saccharomyces cerevisiae
Authors: Timblin Barbara K , Tatchell Kelly , Bergman Lawrence W 
Published: January 2021

Abstract
Pho85, a protein kinase with significant homology to the cyclin-dependent kinase, Cdc28, has been shown to function in repression of transcription of acid phosphatase (APase, encoded by PHO5) in high phosphate (Pi) medium, as well as in regulation of the cell cycle at G1/S. We describe several unique phenotypes associated with the deletion of the PHO85 gene including growth defects on a variety of carbon sources and hyperaccumulation of glycogen in rich medium high in Pi. Hyperaccumulation of glycogen in the pho85 strains is independent of other APase regulatory molecules and is not signaled through Snf1 kinase. However, constitutive activation of cAPK suppresses the hyperaccumulation of glycogen in a pho85 mutant. Mutation of the type-1 protein phosphatase encoded by GLC7 only partially suppresses the glycogen phenotype of the pho85 mutant. Additionally, strains containing a deletion of the PHO85 gene show an increase in expression of GSY2. This work provides evidence that Pho85 has functions in addition to transcriptional regulation of APase and cell-cycle progression including the regulation of glycogen levels in the cell and may provide a link between the nutritional state of the cell and these growth related responses.
Gene Genealogies Within Mutant Allelic Classes
Authors: Slatkin Montgomery 
Published: January 2021

Abstract
A coalescent theory of the gene genealogy within an allelic class that arises by a unique mutational event is developed and analyzed. To interpret this theory it was necessary to expand on existing theory for populations of varying size. Two features of the gene genealogy—the average pairwise distance and the total tree length—within the mutant class and within the nonmutant class are found. An index, I, is proposed that describes the extent to which a genealogy is similar to one from a population of constant size (for which I = 0) or to a star genealogy (for which I = 1). The value of I is positive in growing populations and is generally positive for the gene genealogy for the mutant class. The value of lis negative for a population decreasing in size and for the nonmutant class, if the mutant arose recently. The results are discussed in the context of the infinite sites model of mutation, which is appropriate for nucleotide sequence data, and the generalized stepwise mutation model, which is appropriate for microsatellite loci. The same genealogical methods are used to find the probability of at least one recombination event between a nucleotide that defines an allelic class and a marker at a nearby linked site.
The Yeast BSD2-1 Mutation Influences Both the Requirement for Phosphatidylinositol Transfer Protein Function and Derepression of Phospholipid Biosynthetic Gene Expression in Yeast
Authors: Kagiwada Satoshi , Kerns Brian G , McGee Todd P , Fang Min , Hosaka Kohei , Bankaitis Vytas A 
Published: January 2021

Abstract
The BSD2-1 allele renders Saccharomyces cermisiae independent of its normally essential requirement for phosphatidylinositol transfer protein (Secl4p) in the stimulation of Golgi secretory function and cell viability. We now report that BSD2-1 yeast mutants also exhibit yet another phenotype, an inositol auxotrophy. We demonstrate that the basis for this Ino− phenotype is the inability of BSD2-1 strains to derepress transcription of INO1, the structural gene for the enzyme that catalyzes the committed step in de novo inositol biosynthesis in yeast. This constitutive repression of INO1 expression is mediated through specific inactivation of InoSp, a factor required for transactivation of INOl transcription, and we show that these transcriptional regulatory defects can be uncoupled from the “bypass Secl4p” phenotype of BSD2-1 strains. Finally, we present evidence that newly synthesized phosphatidylinositol is subject to accelerated turnover in BSD2-1 mutants and that prevention of this accelerated phosphatidylinositol turnover in turn negates suppression of Secl4p defects by BSD2-1. We propose that, in BSD2-1 strains, a product(s) generated by phosphatidylinositol turnover coordinately modulates the activities of both the Secl4p/Golgi pathway and the pathway through which transcription of phospholipid biosynthetic genes is derepressed.
Cold-Sensitive Mutations of Dictyostelium Myosin Heavy Chain Highlight Functional Domains of the Myosin Motor
Authors: Patterson Bruce , Spudich James A 
Published: January 2021

Abstract
Dictyostelium provides a powerful environment for characterization of myosin II function. It provides wellestablished biochemical methods for in vitro analysis of myosin's properties as well as an array of molecular genetic tools. The absence of myosin function results in an array of phenotypes that can be used to genetically manipulate myosin function. We have previously reported methods for the isolation and identification of rapideffect cold-sensitive myosin II mutations in Dictyostelium. Here, we report the development and utilization of a rapid method for localizing these point mutations. We have also sequenced 19 mutants. The mutations show distinct clustering with respect to three-dimensional location and biochemically characterized functional domains of the protein. We conclude that these mutants represent powerful tools for understanding the mechanisms driving this protein motor.
Identification, Mapping and Linkage Analysis of Randomly Amplified DNA Polymorphisms in Tetrahymena thermophila
Authors: Brickner Jason H , Lynch Timothy J , Zeilinger Dawn , Orias Eduardo 
Published: January 2021

Abstract
Using the random amplified polymorphic DNA (RAPD) technique and exploiting the unique genetics of Tetrahymena themnophila, we have identified and characterized 40 DNA polymorphisms occurring between two inbred strains (B and C3) of this ciliated protozoan. These RAPD markers permit the PCR amplification of a DNA species using template DNA from SB1969 (B strain) but fail to do so using DNA from C3-368-5 (C3 strain). Polymorphisms were mapped to chromosomes using a panel of monosomic strains constructed by crossing B strainderived nullisomic strains to inbred strain C3. They map to all five chromosomes and appear to be evenly distributed throughout the genome. Chromosomal groups were then analyzed for linkage using meiotic segregants; four linkage groups were identified in chromosomes IR, 2L, 3 and 5. The RAPD method appears useful for the construction of a genetic map of the Tetrahymena genome based on DNA polymorphisms.
Age-Specific Patterns of Genetic Variance in Drosophila melanogaster. II. Fecundity and Its Genetic Covariance With Age-Specific Mortality
Authors: Tatar Marc , Promislow Daniel E L , Khazaeli Aziz A , Curtsinger James W 
Published: January 2021

Abstract
Under the mutation accumulation model of senescence, it was predicted that the additive genetic variance (VA) for fitness traits will increase with age. We measured age-specific mortality and fecundity from 65,134 Drosophila melanogaster and estimated genetic variance components, based on reciprocal crosses of extracted second chromosome lines. Elsewhere we report the results for mortality. Here, for fecundity, we report a bimodal pattern for VA with peaks at 3 days and at 17–31 days. Under the antagonistic pleiotropy model of senescence, it was predicted that negative correlations will exist between early and late life history traits. For fecundity itself we find positive genetic correlations among age classes &gt;3 days but negative nonsignificant correlations between fecundity at 3 days and at older age classes. For fecundity vs. age-specific mortality, we find positive fitness correlations (negative genetic correlations) among the traits at all ages &gt;3 days but a negative fitness correlation between fecundity at 3 days and mortality at the oldest ages (positive genetic correlations). For age-specific mortality itself we find overwhelmingly positive genetic correlations among all age classes. The data suggest that mutation accumulation may be a major source of standing genetic variance for senescence.