bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NEW MAPPING METHOD EMPLOYING A MEIOTIC REC- MUTANT OF YEAST
Authors: Klapholz Sue , Esposito Rochelle Easton 
Published: April 2021

ABSTRACT
A rapid new mapping method has been developed for localizing a dominant or recessive mutation to a particular chromosome of yeast. The procedure utilizes the ability of strains homozygous for the spo11-1 mutation to undergo chromosome segregation without appreciable recombination during sporulation. The level of sporulation in spo11-1/spo11-1 diploids is reduced and asci are often immature or abnormal in appearance; spore viability is less than 1%. The first step of the mapping procedure is the construction of a haploid spo11-1 strain carrying a recessive drug-resistance marker and the unmapped mutation(s). This strain is crossed to a set of three spo11-1 mapping tester strains containing, among them, a recessive marker on each chromosome. The resulting spo11-1/spo11-1 diploids are sporulated and plated on drug-containing medium. Viable meiotic products that express the drug-resistance marker due to chromosome haploidization are selectively recovered. These meiotic products are haploid for most, but generally not all, chromosomes. The level of disomy for individual chromosomes averages 19%. Each of the recessive chromosomal markers is expressed in approximately a third of the drug-resistant segregants. Ninety-eight percent of these segregants show no evidence of intergenic recombination. Thus, two markers located on the same chromosome, but on different homologs, are virtually never expressed in the same drug-resistant clone. The utility of this mapping procedure is demonstrated by confirming the chromosomal location of seven known markers, as well as by the assignment of a previously unmapped mutation, spo12-1, to chromosome VIII. In addition, the analysis of the products of spo11-1 meiosis indicates that several markers previously assigned to either chromosome XIV or chromosome XVII are actually on the same chromosome.
ANALYSIS OF THE ALBINO-LOCUS REGION OF THE MOUSE: IV. CHARACTERIZATION OF 34 DEFICIENCIES
Authors: Russell Liane B , Montgomery Clyde S , Raymer G D 
Published: April 2021

ABSTRACT
Thirty-four independent nonviable c-locus mutations (types cal, albino lethal and cas, albino subvital), derived from radiation experiments, were tested for involvement of nearby markers tp, Mod-2, sh-1, and Hbb: 10, 22, and 2 involved, respectively, none of these markers, Mod-2 alone, and Mod-2 plus sh-1. When classified on this basis, as well as according to developmental stage at which homozygotes die, and by limited complementation results, the 34 independent mutations fell into 12 groups. From results of a full-scale complementation grid of all 435 possible crosses among 30 of the mutations, we were able to postulate an alignment of eight functional units by which the 12 groups fit a linear pattern. Abnormal phenotypes utilized in the complementation study were deaths at various stages of prenatal or postnatal development, body weight, and reduction or absence of various enzymes. Some of these phenotypes can be separated by complementation (e.g., there is no evidence that mitochondrial malic enzyme influences survival at any age); others cannot thus be separated (e.g., glucose-6-phosphatase deficiency and neonatal death).—We conclude that all of the nonviable albino mutations are deficiencies overlapping at c, and ranging in size from &lt;2cM to 6-11 cM. The characterization of this array of deficiencies should provide useful tools for gene-dosage studies, recombinant-DNA fine-structure analyses, etc. Since many of the combinations of lethals produce viable albino animals that resemble the standard c/c type, we conclude (a) that the c locus contains no sites essential for survival, and (b) that viable nonalbino c-locus mutations (cxv) are the result of mutations within the c cistron. Viable albinos (cav, the majority of radiation-induced c-locus mutations) may be intracistronic mutations or very small deficiencies.
INDIRECT SUPPRESSION INVOLVING BEHAVIORAL MUTANTS WITH ALTERED NERVE EXCITABILITY IN DROSOPHILA MELANOGASTER
Authors: Ganetzky Barry , Wu Chun-Fang 
Published: April 2021

ABSTRACT
Two classes of X-linked behavioral mutants of Drosophila melanogaster, leg-shaking mutants and bang-sensitive mutants, are suppressed by napts (no action potential, temperature-sensitive), an autosomal temperature-sensitive paralytic mutation. So far, napts is found to suppress thirteen mutations at seven loci, two of which produce leg shaking and five bang-sensitivity. Suppression is recessive, occurs at temperatures permissive for napts, and is indirect and function-specific rather than allele-specific. At restrictive temperatures, napts is known to completely block all nerve activity. Several of the mutants suppressed by napts are shown by neurophysiological experiments to have increased nerve excitability. The physiological defect of these mutants as well as their behavioral defect is suppressed by napts. Thus, suppression occurs within individual neurons at the level of excitable membranes and apparently depends on the reduction in membrane excitability caused by napts even under permissive conditions. We suggest that all mutants suppressed by napts may have related defects leading to enhanced nerve excitability. Genetic interactions of this type help reveal functional relationships between different behavioral mutants and suggest ways of isolating new mutants with altered excitable membranes.
THE MATHEMATICS OF MOSAIC ANALYSIS I: THE RELATIONSHIP BETWEEN STURTS AND DISTANCE
Authors: Wyman Robert J , Thomas John B 
Published: April 2021

ABSTRACT
In mosaic fate mapping the fraction of mosaics in which two structures are of different genotype is calculated. This frequency of separation has been called a "distance" and the units of this distance are called "sturts". The fundamental assumption of fate mapping is that the frequency of separation increases continuously with the actual distance between the anlage for these structures on the blastoderm. This paper shows that the frequency of separation does not increase beyond a certain value.—For the current theory to work as proposed, each mosaic animal must be half mutant and half normal. This is rarely the case in collections of mosaics. It has been thought that if some flies are less than half mutant and others more than half, these two types would introduce compensating errors in mapping distance. We show that this is not true and describe the nature of the errors introduced. It is probable that these errors are the main reason that mapping distances reported from different sets of mosaics have not been reproducible. This paper presents methods for the proper handling of data from mosaics with different amounts of mutant tissue.—We prove here that for mosaics with an arbitrary fraction of mutant tissue (m), the largest frequency of separation that can occur is 2m. We prove that sturts underestimate actual distance on the blastoderm by a factor of r/m, where r is the radius of the mutant patch, and that sturts give no information on distances greater than 2r. This, and not double crossing over, is the reason for the nonadditivity of sturts and the shrinking of large distances in sturt measures. Sturtoids overestimate distances by a factor of 1/(2r) and also give no information on distances over 2r. This paper gives formulae for correctly estimating distance when using a collection of mosaics with varying amounts of mutant tissue. We also describe the nature of the errors introduced by convoluted or elongate mosaic boundaries and by multiple mosaic patches.
SITE-SPECIFIC INSTABILITY IN DROSOPHILA MELANOGASTER: EVIDENCE FOR TRANSPOSITION OF DESTABILIZING ELEMENT
Authors: Laverty Todd R , Lim J K 
Published: April 2021

ABSTRACT
In this study, we show that at least one lethal mutation at the 3F-4A region of the X chromosome can generate an array of chromosome rearrangements, all with one chromosome break in the 3F-4A region. The mutation at 3F-4A (secondary mutation) was detected in an X chromosome carrying a reverse mutation of an unstable lethal mutation, which was mapped in the 6F1-2 doublet (primary mutation). The primary lethal mutation at 6F1-2 had occurred in an unstable chromosome (Uc) described previously (Lim 1979). Prior to reversion, the 6F1-2 mutation had generated an array of chromosome rearrangements, all having one break in the 6F1-2 doublet (Lim 1979, 1980). In the X chromosomes carrying the 3F-4A secondary lethal mutation the 6F1-2 doublet was normal and stable, as was the 3F-4A region in the X chromosome carrying the primary lethal mutation. The disappearance of the instability having a set of genetic properties at one region (6F1-2) accompanied by its appearance elsewhere in the chromosome (3F-4A) implies that a transposition of the destabilizing element took place. The mutant at 3F-4A and other secondary mutants exhibited all but one (reinversion of an inversion to the normal sequence) of the eight properties of the primary lethal mutations. These observations support the view that a transposable destabilizing element is responsible for the hypermutability observed in the unstable chromosome and its derivaties.
Sex-related differences in crossing over in Caenorhabditis elegans.
Authors: Zetka M C , Rose A M 
Published: April 2021

Abstract
In the nematode Caenorhabditis elegans, hermaphrodite recombination has been characterized and is the basis of the genetic map used in this organism. In this study we have examined male recombination on linkage group I and have found it to be approximately one-third less than that observed in the hermaphrodite. This decrease was interval-dependent and nonuniform. We observed less recombination in the male in 5 out of 6 intervals examined, and no observable difference in one interval on the right end of LG I. Hermaphrodite recombination frequencies are the result of recombination in two germlines; oocyte and hermaphrodite spermatocytes. We have measured recombination in the oocyte and have found it to be approximately twofold lower than that calculated for hermaphrodite spermatocytes and not significantly different from the male spermatocyte frequency. Thus, recombination frequencies appear to be a function of gonad physiology rather than the sex of the germline. Evidence from experiments examining the effect of karyotype on recombination in males sexually transformed by the her-1 mutation into XO hermaphrodites (normally XX), suggests the sexual phenotype rather than genotype determines the recombination frequency characteristic of a particular sex. Hermaphrodite recombination is known to be affected by temperature, maternal age, and the rec-1 mutation. We have examined the effect of these parameters on recombination in the male and have found male recombination frequency increased with elevated temperatures and in the presence of Rec-1, and decreased with paternal age.
Nucleotide sequence and gene organization of the starfish Asterina pectinifera mitochondrial genome.
Authors: Asakawa S , Himeno H , Miura K , Watanabe K 
Published: April 2021

Abstract
The 16,260-bp mitochondrial DNA (mtDNA) from the starfish Asterina pectinifera has been sequenced. The genes for 13 proteins, two rRNAs and 22 tRNAs are organized in an extremely economical fashion, similar to those of other animal mtDNAs, with some of the genes overlapping each other. The gene organization is the same as that for another echinoderm, sea urchin, except for the inversion of a 4.6-kb segment that contains genes for two proteins, 13 tRNAs and the 16S rRNA. Judging from the organization of the protein coding genes, mammalian mtDNAs resemble the sea urchin mtDNA more than that of the starfish. The region around the 3' end of the 12S rRNA gene of the starfish shows a high similarity with those for vertebrates. This region encodes a possible stem and loop structure; similar potential structures occur in this region of vertebrate mtDNAs and also in nonmitochondrial small subunit rRNA. A similar stem and loop structure is also found at the 3' end of the 16S rRNA genes in A. pectinifera, in another starfish Pisaster ochraceus, in vertebrates and in Drosophila, but not in sea urchins. The full sequence data confirm the presumption that AGA/AGG, AUA and AAA codons, respectively, code for serine, isoleucine, and asparagine in the starfish mitochondria, and that AGA/AGG codons are read by tRNA(GCUSer), which possesses a truncated dihydrouridine arm, that was previously suggested from a partial mtDNA sequence. The structural characteristics of tRNAs and possible mechanisms for the change in the mitochondrial genetic code are also discussed.
Sodium orthovanadate-resistant mutants of Saccharomyces cerevisiae show defects in Golgi-mediated protein glycosylation, sporulation and detergent resistance.
Authors: Kanik-Ennulat C , Montalvo E , Neff N 
Published: April 2021

Abstract
Orthovanadate is a small toxic molecule that competes with the biologically important oxyanion orthophosphate. Orthovanadate resistance arises spontaneously in Saccharomyces cerevisiae haploid cells by mutation in a number of genes. Mutations selected at 3 nM sodium orthovanadate have different degrees of vanadate resistance, hygromycin sensitivity, detergent sensitivity and sporulation defects. Recessive vanadate-resistant mutants belong to at least six genetic loci. Most mutants are defective in outer chain glycosylation of secreted invertase (van1, van2, van4, van5, van6, VAN7-116 and others), a phenotype found in some MNN or VRG mutants. The phenotypes of these vanadate-resistant mutants are consistent with an alteration in the permeability or specificity of the Golgi apparatus. The previously published VAN1 gene product has a 200 amino acid domain with 40% identity with the MNN9 gene product and 70% identity with the ANP1 gene product. Cells containing the van1-18, mnn9 (vrg6) or anp1 mutations have some phenotypic similarities. The VAN2 gene was isolated and its coding region is identified and reported. It is an essential gene on chromosome XV and its translated amino acid sequence predicts a unique 337 amino acid protein with multiple transmembrane domains.
Alterations in ribosomal protein RPS28 can diversely affect translational accuracy in Saccharomyces cerevisiae.
Authors: Anthony R A , Liebman S W 
Published: April 2021

Abstract
Three small-subunit ribosomal proteins shown to influence translational accuracy in Saccharomyces cerevisiae are conserved in structure and function with their procaryotic counterparts. One of these, encoded by RPS28A and RPS28B (RPS28), is comparable to bacterial S12. The others, encoded by sup44 (RPS4) or, sup46 and YS11A (RPS13), are homologues of procaryotic S5 and S4, respectively. In Escherichia coli, certain alterations in S12 cause hyperaccurate translation or antibiotic resistance that can be counteracted by other changes in S5 or S4 that reduce translational accuracy. Using site-directed and random mutagenesis, we show that different changes in RPS28 can have diametrical influences on translational accuracy or antibiotic sensitivity in yeast. Certain substitutions in the amino-terminal portion of the protein, which is diverged from the procaryotic homologues, cause varying levels of nonsense suppression or antibiotic sensitivity. Other alterations, found in the more conserved carboxyl-terminal portion, counteract SUP44- or SUP46-associated antibiotic sensitivity, mimicking E. coli results. Although mutations in these different parts of RPS28 have opposite affects on translational accuracy or antibiotic sensitivity, additive phenotypes can be observed when opposing mutations are combined in the same protein.
Colonization of the Americas by Drosophila subobscura: lethal-gene allelism and association with chromosomal arrangements.
Authors: Mestres F , Serra L , Ayala F J 
Published: April 2021

Abstract
Drosophila subobscura is a Palearctic species that has recently colonized the Americas. It was first found in 1978 in Puerto Montt, Chile, and in 1982 in Port Townsend, WA. The colonization and rapid expansion of the species in western South and North America provides distinctive opportunities for investigating the process of evolution in action. The inversion polymorphism in the O chromosome from populations of central California and northern Washington, separated by 1300 km, corresponds to a previously observed latitudinal cline, also observed in Europe. Recessive lethal genes are not randomly distributed among the chromosomal arrangements. The incidence of lethal allelism is high, yielding unrealistically low estimates of the effective size of these populations (on the order of 1000 individuals). The high incidence of lethal allelism is likely to be a consequence of the low number of the American colonizers (on the order of 10-100 individuals), but the persistence of the allelism over several years suggests that some lethal-carrying chromosomes may be heterotic owing to shared associations between lethal and other genes.
A screen for modifiers of Deformed function in Drosophila.
Authors: Harding K W , Gellon G , McGinnis N , McGinnis W 
Published: April 2021

Abstract
Proteins produced by the homeotic genes of the Hox family assign different identifies to cells on the anterior/posterior axis. Relatively little is known about the signalling pathways that modulate their activities or the factors with which they interact to assign specific segmental identifies. To identify genes that might encode such functions, we performed a screen for second site mutations that reduce the viability of animals carrying hypomorphic mutant alleles of the Drosophila homeotic locus, Deformed. Genes mapping to six complementation groups on the third chromosome were isolated as modifiers of Deformed function. Products of two of these genes, sallimus and moira, have been previously proposed as homeotic activators since they suppress the dominant adult phenotype of Polycomb mutants. Mutations in hedgehog, which encodes secreted signalling proteins, were also isolated as Deformed loss-of-function enhancers. Hedgehog mutant alleles also suppress the Polycomb phenotype. Mutations were also isolated in a few genes that interact with Deformed but not with Polycomb, indicating that the screen identified genes that are not general homeotic activators. Two of these genes, cap 'n' collar and defaced, have defects in embryonic head development that are similar to defects seen in loss of function Deformed mutants.
Complete sequence and gene organization of the mitochondrial genome of the land snail Albinaria coerulea.
Authors: Hatzoglou E , Rodakis G C , Lecanidou R 
Published: April 2021

Abstract
The complete sequence (14,130 bp) of the mitochondrial DNA (mtDNA) of the land snail Albinaria coerulea was determined. It contains 13 protein, two rRNA and 22 tRNA genes. Twenty-four of these genes are encoded by one and 13 genes by the other strand. The gene arrangement shares almost no similarities with that of two other molluscs for which the complete gene content and arrangement are known, the bivalve Mytilus edulis and the chiton Katharina tunicata; the protein and rRNA gene order is similar to that of another terrestrial gastropod, Cepaea nemoralis. Unusual features include the following: (1) the absence of lengthy noncoding regions (there are only 141 intergenic nucleotides interspersed at different gene borders, the longest intergenic sequence being 42 nucleotides) (2) the presence of several overlapping genes (mostly tRNAs), (3) the presence of tRNA-like structures and other stem and loop structures within genes. An RNA editing system acting on tRNAs must necessarily be invoked for posttranscriptional extension of the overlapping tRNAs. Due to these features, and also because of the small size of its genes (e.g., it contains the smallest rRNA genes among the known coelomates), it is one of the most compact mitochondrial genomes known to date.
GENETIC MODULATION OF RNA METABOLISM IN DROSOPHILA. I. INCREASED RATE OF RIBOSOMAL RNA SYNTHESIS
Authors: Clark Stephen H , Strausbaugh Linda D , Kiefer Barry I 
Published: April 2021

ABSTRACT
It has been suggested that a particular Y chromosome which is rDNA-deficient (YbbSuVar-5) may be associated with an increased utilization of rDNA template in adult testes (Shermoen and Kiefer 1975). To extend the observations on this chromosome, experiments were designed to determine if the chromosome has an effect on rRNA synthesis in bobbed adults and on classic bobbed phenotypes (shortened and thinner scutellar bristles and delayed development). Specific activity measurements were made on rRNA extracted from adult males of the genotypes car bb/Ybb- and car bb/YbbSuVar-5, which are rDNA-deficient to the same extent, and from Samarkand+ isogenic (Sam+ iso), which is a wild-type stock. The resulting data demonstrated that the presence of the YbbSuVar-5 chromosome increases the rate of ribosomal RNA synthesis in adult flies. In addition, it was found that the presence of this particular Y chromosome restores wild-type bristle phenotype and development time. Appropriate genetic crosses indicate that the observed effects (increased rRNA synthesis, restoration of wild-type phenotype) are a function of this particular Y chromosome, and are not due to autosomal factors. The results of these experiments suggest that the rate of rRNA accumulation is under genetic control.
INDUCTION OF THIOGUANINE- AND OUABAIN-RESISTANT MUTANTS AND SINGLE-STRAND BREAKS IN THE DNA OF CHINESE HAMSTER OVARY CELLS BY 3H-THYMIDINE
Authors: Cleaver James E 
Published: April 2021

ABSTRACT
Cultured Chinese hamster cells were labeled with 6-3H-thymidine or 5-methyl-3H-thymidine and allowed to accumulate damage from 3H decays for various periods of time while frozen. The frequencies of cells resistant to 6-thioguanine or ouabain and the amount of DNA damage (i.e., number of single-strand breaks) were determined and compared with the mutation frequencies resulting from X and ultraviolet light irradiation. Whereas 3H decays and X rays made only 6-thioguanine-resistant mutants, ultraviolet light made both 6-thioguanine- and ouabain-resistant mutants. 3H decays originating at the 6 position were two to three times as effective as decays at the 5-methyl position in making drug-resistant mutants, but decays at both sites were equally effective in making single-strand breaks. Mutants and strand breaks produced by beta irradiation of the nucleus probably are the same irrespective of the site of the decay in thymine; these results indicate that the local transmutation effects of 3H decay produce more mutations when they occur at the 6 position than at the 5-methyl position.
ALLELIC VARIANTS AT THE XANTHINE DEHYDROGENASE LOCUS AFFECTING ENZYME ACTIVITY IN DROSOPHILA PSEUDOOBSCURA
Authors: Prakash Satya 
Published: April 2021

ABSTRACT
Quantitative studies of enzyme activity on gels show about four-fold differences in enzyme activity of different xanthine dehydrogenase (XDH) alleles. At least three different activity classes could be distinguished among the 23 strains isogenic for the XDH locus. No association of high activity with the high frequency electromorph was observed; instead, the low frequency electromorphs had 0.5 to 2 times the activity of the high frequency electromorph. The frequency of low activity, high activity and intermediate activity XDH alleles among these 23 lines is 0.13, 0.09, and 0.78, respectively.