bluuebunny/crossref_metadata_2025_split huggingface dataset:
STE16, a New Gene Required for Pheromone Production by a Cells of Saccharomyces cerevisiae
Authors: Wilson Katherine L , Herskowitz Ira 
Published: January 2021

ABSTRACT
Genes required for mating by a and α cells of Saccharomyces cerevisiae (STE, "sterile," genes) encode products such as peptide pheromones, pheromone receptors, and proteins responsible for pheromone processing. a-specific STE genes are those required for mating by a cells but not by α cells. To identify new a-specific STE genes, we have employed a novel strategy that enabled us to determine if a ste mutant defective in mating as a is also defective in mating as α without the need to do crosses. This technique involved a strain (K12-14b) of genotype mat a 1 HML? HMR? sir3ts, which mates as a at 25° and as α at 34°. We screened over 40,000 mutagenized colonies derived from K12-14b and obtained 28 a-specific ste mutants. These strains contained mutations in three known a-specific genes- STE2, STE6 and STE14-and in a new gene, STE16. ste16 mutants are defective in the production of the pheromone, a-factor, and exhibit slow growth. Based on the distribution of a-specific ste mutants described here, we infer that we have identified most if not all nonessential genes that can give rise to a-specific mating defects.
Genetic Transformation of Drosophila melanogaster with an Autonomous P Element: Phenotypic and Molecular Analyses of Long-Established Transformed Lines
Authors: Daniels Stephen B , Clark Stephen H , Kidwell Margaret G , Chovnick Arthur 
Published: January 2021

ABSTRACT
Following transformation of a Drosophila melanogaster true M strain with an autonomous P element, six lines were established and monitored for their molecular and phenotypic properties during a 4-yr period. The number of P elements increased with time in all the lines but the rate of increase differed among lines. Furthermore, degenerate elements arose in each of the lines during propagation. By the end of the 4th yr, the total number of elements in every line was similar to that of a very strong P strain.—At the phenotypic level, all of the transformed lines evolved high P activity, but only three developed complete or nearly complete regulatory ability. The other three lines attained only intermediate levels of regulation over the 4-yr period. One of these lines was particularly noteworthy. Although it contained as many as 55 P elements per genome (20 of which were potentially complete) and had extremely high P activity potential, it continued to exhibit limited regulatory ability. In addition, when females of this line were maintained at high temperatures, the ability to suppress P activity was even further diminished. A strain with this combination of molecular and phenotypic properties, in an apparently stable configuration, has not been previously described.—The results are discussed in the context of the possible role of degenerate elements in regulating P element expression.
Genetic Hitchhiking and the Evolution of Reduced Genetic Activity of the Y Sex Chromosome
Authors: Rice William R 
Published: January 2021

ABSTRACT
A new model for the evolution of reduced genetic activity of the Y sex chromosome is described. The model is based on the process of genetic hitchhiking. It is shown that the Y chromosome can gradually lose its genetic activity due to the fixation of deleterious mutations that are linked with other beneficial genes. Fixation of deleterious Y-linked mutations generates locus-specific selection for dosage tolerance and/or compensation. The hitchhiking effect is most pronounced when operating in combination with an alternative model, Muller's ratchet. It is shown, however, that the genetic hitchhiking mechanism can operate under conditions where Muller's ratchet is ineffective.
Mutations Affecting Expression of the rosy Locus in Drosophila melanogaster
Authors: Lee Chong Sung , Curtis Daniel , McCarron Margaret , Love Carol , Gray Mark , Bender Welcome , Chovnick Arthur 
Published: January 2021

ABSTRACT
The rosy locus in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase (XDH). Previous studies defined a "control element" near the 5′ end of the gene, where variant sites affected the amount of rosy mRNA and protein produced. We have determined the DNA sequence of this region from both genomic and cDNA clones, and from the ry +10 underproducer strain. This variant strain had many sequence differences, so that the site of the regulatory change could not be fixed. A mutagenesis was also undertaken to isolate new regulatory mutations. We induced 376 new mutations with 1-ethyl-1-nitrosourea (ENU) and screened them to isolate those that reduced the amount of XDH protein produced, but did not change the properties of the enzyme. Genetic mapping was used to find mutations located near the 5′ end of the gene. DNA from each of seven mutants was cloned and sequenced through the 5′ region. Mutant base changes were identified in all seven; they appear to affect splicing and translation of the rosy mRNA. In a related study (T. P. Keith et al. 1987), the genomic and cDNA sequences are extended through the 3′ end of the gene; the combined sequences define the processing pattern of the rosy transcript and predict the amino acid sequence of XDH.
Dosage-Dependent Modifiers of Homoeotic Mutations in Drosophila melanogaster
Authors: Kennison James A , Russell Michael A 
Published: January 2021

ABSTRACT
The determination of segment identity in Drosophila melanogaster appears to be controlled by a small number of genes. In order to identity new components in the process, we have systematically screened the autosomal complement for loci that show a dosage-dependent interaction with mutations in previously characterized genes thought to be important in the determination of segment identity. The dominant homoeotic phenotype of mutations at four loci involved in thoracic leg determination (Pc, Pcl, Antp and Scr) were quantitated in flies bearing a series of synthetic duplications covering more than 99% of the autosomal complement. Twelve regions were identified that when present in three wild-type copies strongly enhanced or suppressed the phenotype of mutations at one or more of the four homoeotic loci examined. The effects of five of these regions appear to correspond to previously described homoeotic loci; the effects of the remaining seven appear to identify new loci involved in the determination of segment identity.
Complete Nucleotide Sequence of the Mouse Lactate Dehydrogenase-A Functional Gene: Comparison of the Exon-Intron Organization of Dehydrogenase Genes
Authors: Fukasawa Kayoko M , Li Steven S-L 
Published: January 2021

ABSTRACT
The complete sequence of 12,851 nucleotides of the mouse lactate dehydrogenase-A (LDH-A) gene has been determined. It includes eight exons, seven introns, promoter and regulatory regions. The B1 repetitive elements present in intron III and VI are oriented in opposite orientation, and they share 72% sequence homology. The exon-intron organization of mouse LDH-Agene is compared with the organizations of other dehydrogenase genes, and the molecular evolution of the nicotinamide adenine dinucleotide binding domains is discussed.
Organ-Specific Expression of Maize Adh1 Is Altered After a Mu Transposon Insertion
Authors: Chen Che-Hong , Oishi Karen K , Kloeckener-Gruissem Barbara , Freeling Michael 
Published: January 2021

ABSTRACT
A new, unstable, organ-specific Adh1 mutant was isolated from a Robertson's mutator line by germinating kernels under partial anaerobic conditions. Families of kernels which showed segregation of a conditional anaerobic lethal phenotype were identified. One mutant, Adh1-3F1124, was shown to express approximately 6% normal levels of ADH1 in seed and anaerobically treated seedlings but expresses normal levels of ADH1 in pollen, the male gametophyte. The ADH1 polypeptide encoded by the mutant allele was found to be indistinguishable from that encoded by the Adh1-3F progenitor but its message levels were lower in seed and seedlings. Robertson's mutator lines are known to carry Mu transposons that cause increased mutation rates. Genomic Southern analysis of Adh1-3F1124 and Adh1-3F showed the presence of a 1.85 kbp insertion at the 5′ region of Adh1. Comparison of the DNA sequences revealed that a Mu1-like element was inserted 31 bp 5′ from the transcriptional start site of Adh1-3F1124gene. The insertion of the Mu element creates an additional TATA box by duplicating the 9 bp genomic sequence—ATATAAATC—at the site of insertion. Consequently, there are two potentially functional TATA sequences, separated by the 1.85 kbp Mu element, 5′ to the transcriptional start site. It is not yet understood how such an arrangement alters the organspecific expression of Adh1.
Chloroplast Genome Evolution in the Genus Avena
Authors: Murai Koji , Tsunewaki Koichiro 
Published: January 2021

ABSTRACT
The genus Avena contains five different chloroplast genomes, I-V. A physical map of chloroplast (ct) DNA of Avena sativa (type I chloroplast genome) was constructed using three restriction endonucleases, PstI, SalI and SmaI. This genome is ca. 135.5 kbp in size, and contains two inverted repeats of ca. 22.5 kbp each, separated by a large (ca. 79.0 kbp) and small (ca. 12.5 kbp) single copy region. The rbcL gene which codes for the large subunit of ribulose 1,5-bisphosphate carboxylase, was located in the map. Restriction fragment patterns of all five chloroplast genomes were compared, and among them five fragment size and five restriction site mutations were disclosed. Four site mutations were found in two or more chloroplast genomes, the other site and five fragment size mutations were specific to one or another of the chloroplast genomes. A dendrogram showing phylogenetic relationships among the five chloroplast genomes, based on the distribution of the common and specific mutations among them, indicates that chloroplast genome divergence characterized by three restriction site mutations occurred first between two diploid groups, each carrying A and C genome (nuclear), respectively, followed by further speciation in each group.
Nucleo-Cytoplasmic Interaction During Macronuclear Differentiation in Ciliate Protists: Genetic Basis for Cytoplasmic Control of SerH Expression During Macronuclear Development in Tetrahymena thermophila
Authors: Doerder F P , Berkowitz M S 
Published: January 2021

ABSTRACT
A novel class of mutations affecting the developmental expression of SerH cell surface antigen genes of Tetrahymena thermophila is described. Unlike previous categories of mutation, the four independently isolated mutations of this class act through the cytoplasm to affect SerH genes during macronuclear development. That is, macronuclei which develop under the influence of mutant cytoplasm do not subsequently express H, most likely because the developmental processing of SerH genes is affected. The cytoplasmic effect is specific for the SerH locus and is independent of which SerH allele is present. In place of H, hitherto unknown antigens are expressed. Expression of SerH can be rescued during development either by wild-type cytoplasm exchanged between conjugants or by the homozygous wild-type genotype. The mutations segregate independently of the SerH genes and identify one, possibly two, bistable genes. Possible models to explain these results are discussed.
Genetic Diversity in Cellular Slime Molds: Allozyme Electrophoresis and a Monoclonal Antibody Reveal Cryptic Species Among Dictyostelium discoideum Strains
Authors: Briscoe David A , Gooley Andrew A , Bernstein R L , McKay George M , Williams Keith L 
Published: January 2021

ABSTRACT
Cellular slime molds have been classified on the basis of a small number of descriptive criteria such as fruiting body color and morphology, and, in heterothallic species, by assignment to compatible mating groups. However, some isolates which are morphologically classified as conspecific do not fall into a simple mating-type classification; for example some are asexual or homothallic. An increasing interest in inter-strain genetic variation in studies of development and simple behavior has led us to reassess genetic relationships among a number of frequently used isolates. Allozyme electrophoresis of 16 soluble enzymes and use of a monoclonal antibody show that there is relatively little genetic diversity among sexually competent Dictyostelium discoideum isolates, despite considerable variation in geographic origin and time since isolation in the laboratory. In contrast a pair of asexual strains and each of two homothallic strains are genetically quite distinct and differ sufficiently from each other, and from sexually competent isolates, to warrant their recognition as separate species. There are probably four biological species represented in the supposedly D. discoideum isolates studied. This heterogeneity extends to other cellular slime mold species. Each of three isolates of Dictyostelium purpureum is genetically distinct from the others. Limited analysis of other cellular slime molds indicates that the generic distinction of Dictyostelium and Polysphondylium must be questioned. This study emphasizes that caution should be applied in classifying simple organisms on morphological criteria.
Isolation and Characterization of a 1.7-kb Transposable Element from a Mutator Line of Maize
Authors: Taylor Loverine P , Walbot Virginia 
Published: January 2021

ABSTRACT
We have cloned and sequenced a 1.7-kb Mu element from a Mutator line of maize and compared its structure to Mu1, a 1.4-kb element. With the exception of a 385-bp block of DNA present in the 1.7-kb element, these transposable elements are structurally similar, sharing terminally inverted and internal direct repeated sequences. Derivation of 1.4-kb elements from the 1.7-kb class via deletion of internal sequence is suggested by the finding that a portion of the extra DNA in Mu1.7 is part of a truncated direct repeat sequence in the 1.4-kb element. An abundant poly(A)+ RNA homologous to a portion of this extra DNA is present in several tissues of both Mutator and non-Mutator lines. Analysis of transcripts from an unstable mutant bronze1 (bz) allele containing a Mu1.7 element inserted in an exon of the gene detects three species of poly(A)+ RNA that hybridize to a Bz1 (Bronze) gene probe: the largest contains the entire Mu1.7 element in the Bz1 gene transcript; another appears to be a spliced, chimeric transcript; the smallest is normal size Bz1 mRNA. The latter is most likely encoded by the normal-size alleles detected by Southern analysis of tissue expressing purple pigment, suggesting that normal gene function is restored by excision of the Mu1.7 element.
Interaction of Endosperm Size Factors in Maize
Authors: Birchler James A , Hart Jennifer R 
Published: January 2021

ABSTRACT
Crosses involving certain B-A translocations produce a reduced size of endosperm when those regions of the A chromosomes are missing in the sperm that fertilizes the polar nuclei. Previous studies involving the long arm of chromosome 10 showed that additional copies of this segment introduced through the maternal side could not rescue the reduced size phenotype conditioned by the corresponding deficiency in the paternal gamete. In this paper, experiments are described showing that other segments introduced maternally produce an even smaller kernel when fertilized by a sperm missing the same A chromosome segment or other ones that carry factors affecting endosperm size.—The example analyzed in detail involves reciprocal crosses between TB-4Sa and TB-10L19. Extra doses of 4S enhance the small kernel effect normally produced by TB-10L19. The additional copies of 4S have no effect on kernel mass when the 10L segment is present in the paternal contribution to the endosperm. The maternal enhancement by 4S is also effective with crosses by TB-1La but not by TB-1Sb. A survey of inter se crosses of B-A translocations shows that, when the maternal enhancement occurs, it is confined to those regions that themselves give a small kernel effect when used as a male. This correlation is strengthened by the observations that TB-10L19 enhances the small kernel effect of TB-1Sb, but TB-10L32 will not. Since these two B-10L translocations span the best localized small kernel effect region, this result supports the correlation of maternal enhancement regions with the paternal small kernel effect ones.—Because the enhancement can be attributed to a dosage effect and because the enhancement regions are coincident with the small kernel segments, it is postulated that this interacting system is analogous to aneuploid effects in diploid tissues but exhibits unique properties because of the evolutionary history and triploid condition of the endosperm.
A New Non-Mendelian Genetic Element of Yeast That Increases Cytopathology Produced by M1 Double-Stranded RNA in ski Strains
Authors: Esteban Rosa , Wickner Reed B 
Published: January 2021

ABSTRACT
The Saccharomyces cerevisiae SKI (superkiller) genes are repressors of replication of M, L-A, and L-BC double-stranded (ds) RNAs; ski strains have an increased M dsRNA copy number and, as a result, are cold-sensitive for growth at 8°. Growth is normal, however, at higher temperatures. We have found a new cytoplasmic genetic element [D] (for disease) that makes M1 dsRNA-containing superkiller strains grow slowly at 30°, not at all at 37°, and only very poorly at 20°. These growth defects require three factors: a chromosomal ski mutation, the presence of M1 dsRNA, and the presence of the new cytoplasmic factor, [D]. We have isolated mutants unable to ma intain [D] (mad), at least one of which is due to mutation of a single chromosomal locus. Further, [D] can be cured by growth at 37-39°. We present evidence that [D] is not M, L-A, L-BC or W dsRNAs or mitochondrial DNA, 2µ DNA, or [psi], but [D] depends on L-A for its maintenance. We also show that [D] is distinct from [B], a cytoplasmic element that allows M1 dsRNA to be stably replicated and maintained in spite of defects in certain chromosomal MAK genes that would otherwise be necessary. [D] activity is blocked by the presence of another extrachromosomal element, called [DIN] (for [D] interference). [D] and [DIN] may be different natural variants of the same molecule.
Proposed Mechanism of Inheritance and Expression of the Human Fragile-X Syndrome of Mental Retardation
Authors: Laird Charles D 
Published: January 2021

ABSTRACT
A mechanism is proposed for the inheritance and expression of the fragile-X-linked syndrome of mental retardation in humans. Two independent events are required for expression of the syndrome: the fragile-X mutation, and X chromosome inactivation in pre-oogonial cells. The fragile-X mutation at site Xq27 has little or no effect until the chromosome is inactivated in a female as part of the process of dosage compensation. At a stage where the inactivated X chromosome would normally be reactivated in preparation for oogenesis, the mutation results in a local block to the reactivation process. This block to reactivation leads to mental retardation in progeny by reducing the level of products from the unreactivated Xq27 region in male cells, and, for a heterozygous female, in somatic cells in which the normal X chromosome has been inactivated. Published data relevant to this proposed mechanism are discussed.
Evidence for Related Functions of the RNA Genes of Saccharomyces cerevisiae
Authors: Last Robert L , Maddock Janine R , Woolford John L 
Published: January 2021

ABSTRACT
The yeast genes RNA2-RNA11 are necessary for splicing of nuclear intron-containing pre-mRNAs. We investigated the relationships among these genes by asking whether increased expression of one RNA gene leads to suppression of the temperature-sensitive lethality of a mutation in any other RNA gene. The presence of extra plasmid-borne copies of the RNA3 gene relieves the lethality of temperature-sensitive rna4 mutations. A region of the yeast genome (SRN2) is described that suppresses temperature-sensitive rna2 mutations when it is present on either medium or high-copy number plasmids. Neither suppression occurs via a bypass of RNA gene function since null alleles of rna2 and rna4 are not suppressed by elevated dosage of SRN2 and RNA3, respectively. These results suggest that the SRN2 and RNA2 gene products have related functions, as do the RNA3 and RNA4 gene products.
Characterization of X-linked recessive lethal mutations affecting embryonic morphogenesis in Drosophila melanogaster.
Authors: Eberl D F , Hilliker A J 
Published: January 2021

Abstract
This study attempted to assay the zygotic contribution of X chromosome genes to the genetic control of embryonic morphogenesis in Drosophila melanogaster. A systematic screen for X-linked genes which affect the morphology of the embryo was undertaken, employing the phenotype of whole mount embryos as the major screening criterion. Of 800 EMS-induced lethal mutations analyzed, only 14% were embryonic lethal, and of these only a minority affected embryonic morphogenesis. By recombination and complementation analyses, the mutations that affected embryonic morphogenesis were sequestered into 26 complementation groups. Fourteen of the loci correspond to genes previously identified in a large-scale screen in which fixed cuticles were examined, and 12 new loci have been identified. Most of the mutations which disrupt embryonic morphology had specific and uniform mutant phenotypes. Mutations were recovered which disrupt major morphogenetic events such as gastrulation, germ band retraction and head involution. No mutations were found which arrest the embryos prior to blastoderm formation. However, a novel class was found, one comprised of mutations which interfere with the development of internal structures but not cuticular structures. Nevertheless, saturation of the X chromosome for genes important for embryonic morphogenesis is probably incomplete.
Mutants resistant to anti-microtubule herbicides map to a locus on the uni linkage group in Chlamydomonas reinhardtii.
Authors: James S W , Ranum L P , Silflow C D , Lefebvre P A 
Published: January 2021

Abstract
We have used genetic analysis to study the mode of action of two anti-microtubule herbicides, amiprophos-methyl (APM) and oryzalin (ORY). Over 200 resistant mutants were selected by growth on APM- or ORY-containing plates. The 21 independently isolated mutants examined in this study are 3- to 8-fold resistant to APM and are strongly cross-resistant to ORY and butamiphos, a close analog of APM. Two Mendelian genes, apm1 and apm2, are defined by linkage and complementation analysis. There are 20 alleles of apm1 and one temperature-sensitive lethal (33 degrees) allele of apm2. Mapping by two-factor crosses places apm1 6.5 cM centromere proximal to uni1 and within 4 cM of pf7 on the uni linkage group, a genetically circular linkage group comprising genes which affect flagellar assembly or function; apm2 maps near the centromere of linkage group VIII. Allele-specific synthetic lethality is observed in crosses between apm2 and alleles of apm1. Also, self crosses of apm2 are zygotic lethal, whereas crosses of nine apm1 alleles inter se result in normal germination and tetrad viability. The mutants are recessive to their wild-type alleles but doubly heterozygous diploids (apm1 +/+ apm2) made with apm2 and any of 15 apm1 alleles display partial intergenic noncomplementation, expressed as intermediate resistance. Diploids homozygous for mutant alleles of apm1 are 4-6-fold resistant to APM and ORY; diploids homozygous for apm2 are ts- and 2-fold resistant to the herbicides. Doubly heterozygous diploids complement the ts- phenotype of apM2, but they are typically 1.5-2-fold resistant to APM and ORY. From the results described we suggest that the gene products of apm1 and apm2 may interact directly or function in the same structure or process.