Meiotic analysis of induced mutations in Ophiostoma ulmi

1990 ◽  
Vol 68 (2) ◽  
pp. 232-235 ◽  
Author(s):  
L. Bernier ◽  
M. Hubbes
Keyword(s):  
Linkage Group ◽  
Dutch Elm Disease ◽  
Induced Mutations ◽  
Type Locus ◽  
Meiotic Analysis ◽  
Ophiostoma Ulmi ◽  
Group I ◽  
Disease Mutations ◽  
Nuclear Mutations ◽  
Additional Locus

Laboratory strains of Ophiostoma ulmi carrying nuclear mutations induced by exposure to N-methyl-N′-nitro-N-nitrosoguanidine were crossed, and the segregation of genetic markers was analyzed in random ascospore progeny. Investigation of 13 auxotrophic mutations and 1 benomyl-resistant mutation provided evidence for at least three linkage groups in O. ulmi. Five loci, identified by mutant alleles ade1-1, BENIR-1, cyi1-1, lys3-1, and nic1-1, were assigned to linkage group I, whereas markers ade2-1 and lys2-2 were mapped on linkage group II. An additional locus, Met1, was assigned to a third linkage group since mutant alleles at this locus segregated independently from markers on group I or II. The Ben1R locus, controlling resistance to benomyl, segregated independently from the mating type locus and thus appeared to differ from the Tol locus described by other workers. Key words: Ophiostoma ulmi, Dutch elm disease, mutations, linkage analysis.

scholarly journals REVERSAL OF A NEUROSPORA TRANSLOCATION BY CROSSING OVER INVOLVING DISPLACED rDNA, AND METHYLATION OF THE rDNA SEGMENTS THAT RESULT FROM RECOMBINATION

Genetics ◽  
1986 ◽  
Vol 114 (3) ◽  
pp. 791-817
Author(s):  
David D Perkins ◽  
Robert L Metzenberg ◽  
Namboori B Raju ◽  
Eric U Selker ◽  
Edward G Barry
Keyword(s):  
Linkage Group ◽  
Distal Portion ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Molecular Evidence ◽  
Crossing Over ◽  
Wild Type ◽  
Type Locus ◽  
Group I ◽  
Chromosome Sequence

ABSTRACT In translocation OY321 of Neurospora crassa, the nucleolus organizer is divided into two segments, a proximal portion located interstitially in one interchange chromosome, and a distal portion now located terminally on another chromosome, linkage group I. In crosses of Translocation x Translocation, exceptional progeny are recovered nonselectively in which the chromosome sequence has apparently reverted to Normal. Genetic, cytological, and molecular evidence indicates that reversion is the result of meiotic crossing over between homologous displaced rDNA repeats. Marker linkages are wild type in these exceptional progeny. They differ from wild type, however, in retaining an interstitial block of rRNA genes which can be demonstrated cytologically by the presence of a second, small interstitial nucleolus and genetically by linkage of an rDNA restriction site polymorphism to the mating-type locus in linkage group I. The interstitial rDNA is more highly methylated than the terminal rDNA. The mechanism by which methylation enzymes distinguish between interstitial rDNA and terminal rDNA is unknown. Some hypotheses are considered.

Mutations in Ophiostoma ulmi induced by N-methyl-N′-nitro-N-nitrosoguanidine

1990 ◽  
Vol 68 (2) ◽  
pp. 225-231 ◽  
Author(s):  
L. Bernier ◽  
M. Hubbes
Keyword(s):  
Dutch Elm Disease ◽  
Recessive Mutation ◽  
Wild Type ◽  
Ophiostoma Ulmi ◽  
Cell Age ◽  
Disease Mutations ◽  
Nuclear Locus ◽  
Type Strains ◽  
Yeastlike Cells ◽  
Incubation Buffer

Mutations were induced in Ophiostoma ulmi, the causal agent of Dutch elm disease, by treating yeastlike cells of wild-type strains with the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). The induced frequency of mutation, assessed by scoring the frequency of benomyl-resistant mutants among the surviving population, was highest in treatments that left from 4 to 10% survivors. The survival rate of the cells was affected by mutagen concentration and length of exposure to MNNG, as well as by cell concentration, cell age, pH, and chemical composition of the incubation buffer. Optimal conditions for routine induction of mutants were obtained by resuspending exponentially growing cultures in phosphate buffer at pH 7.5 (2.0 × 107 cells/mL) and treating the cells with MNNG (20 μg/mL) for 90 min with agitation. The proportion of auxotrophs among the survivors increased at least 200-fold when mutagenesis was followed by nystatin enrichment. Most auxotrophs tested were sexually fertile and carried a recessive mutation at a single nuclear locus. The benomyl-resistant phenotype was dominant. Key words: Ophiostoma ulmi, Dutch elm disease, mutations, N-methyl- N′-nitro-N-nitrosoguanidine.

MEIOTIC CHROMOSOME BEHAVIOR OF AN INVERTED INSERTIONAL TRANSLOCATION IN NEUROSPORA

Genetics ◽  
1972 ◽  
Vol 71 (1) ◽  
pp. 53-62
Author(s):  
Edward G Barry
Keyword(s):  
Linkage Group ◽  
Meiotic Chromosome ◽  
Chromosome 1 ◽  
Homologous Region ◽  
Supporting Evidence ◽  
Type Locus ◽  
Anaphase Bridges ◽  
Meiotic Chromosomes ◽  
Group I ◽  
New Location

ABSTRACT Cytological study of meiotic chromosomes heterozygous for the T(I⇉II)39311 translocation confirm genetic evidence (Perkins 1972) that a section of linkage group I including the mating type locus has been inserted into linkage group II. Pachytene chromosomes when fully paired show that a segment from chromosome 1 has been inserted into chromosome 6. When pairing fails between the translocated segment in 6 and its homologous region in chromosome 1, buckles or loops are formed at pachynema in the deletion or insertion areas of the bivalents.—Acentric fragments and anaphase bridges occur at both meiotic divisions and in the subsequent two mitotic divisions in the ascus. These provide supporting evidence that the translocated segment is inverted with respect to centromere in its new location.—Unexpectedly the acentric fragment, formed by crossing over in the inverted translocated segment, persists without degradation in a micronucleus, and it replicates and divides in synchrony with the centric chromosomes in adjacent nuclei.

scholarly journals Glycoproteins that exhibit extensive size polymorphisms in Dictyostelium discoideum.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 59-64 ◽  
Author(s):  
E Smith ◽  
A A Gooley ◽  
G C Hudson ◽  
K L Williams
Keyword(s):  
Linkage Group ◽  
Dictyostelium Discoideum ◽  
Allelic Variation ◽  
Surface Glycoprotein ◽  
Developmentally Regulated ◽  
Electrophoretic Variants ◽  
Cellular Slime Mould ◽  
Repeat Units ◽  
Group I ◽  
Cellular Slime

Abstract Electrophoretic variants which arise from amino acid substitutions, leading to charge differences between proteins are ubiquitous and have been used extensively for genetic analysis. Less well documented are polymorphisms in the size of proteins. Here we report that a group of glycoproteins, which share a common carbohydrate epitope, vary in size in different isolates of the cellular slime mould, Dictyostelium discoideum. One of these proteins, PsA, a developmentally regulated prespore-specific surface glycoprotein, has previously been shown to exist in three size forms due to allelic variation at the pspA locus on linkage group I. In this report, a second glycoprotein, PsB, which is also prespore specific but found inside prespore cells, is studied. PsB maps to linkage group II and exhibits at least four different sizes in the isolates examined. We propose that the size polymorphisms are the product of allelic variation at the pspB locus, due to differences in the number of repeat units.

NEW DUPLICATION-GENERATING INVERSIONS IN NEUROSPORA

1969 ◽  
Vol 11 (3) ◽  
pp. 622-638 ◽  
Author(s):  
Barbara C. Turner ◽  
Cecile W. Taylor ◽  
David D. Perkins ◽  
Dorothy Newmeyer
Keyword(s):  
Mating Type ◽  
Break Point ◽  
Low Fertility ◽  
Type Locus ◽  
Complementary Product ◽  
Single Crossing ◽  
Group I ◽  
Distinctive Morphology ◽  
Phenotype Characteristic ◽  
Break Points

Inversion In(ILR)NM176 has one break point at the extreme right end of linkage group I and the other distal to mating type in the left arm. In crosses of Inversion × Normal the products of single crossing over within the inversion are complementary duplication-deficiency classes. One crossover product is viable, with a large segment of IL duplicated and the dispensable right tip presumably deficient. This class has low fertility and distinctive morphology. The complementary product has a large deficiency which results in a pair of white, inviable ascospores. Single exchanges within the heterozygous inversion thus produce asci with 6 Black: 2 White spores; four-strand double exchanges produce 4 B:4 W; and non-exchanges produce asci with 8 B:0 W. Approximate mapping of break points was accomplished by three-point crosses. Precise placement of the left break point between ser-3 and un(55701t), just left of mating type, is based on coverage of markers by the heterozygous duplication. No crossover has been obtained between mating type and the break point, despite extensive efforts. In(ILR)NM176 differs from the inversion In(ILR)H4250 described by Newmeyer and Taylor (1967) in one main respect: the mating type locus is included in the inverted segment of NM176. Consequently, when duplications are generated, the progeny are unisexual and do not have the unstable inhibited phenotype characteristic of H4250 duplication progeny, which are heterozygous for the mating type alleles A and a. Three other inversions which originated independently of In(ILR)NM176 resemble it closely and have similar or identical break points.

Analytical electrofocusing and two-dimensional electrophoresis of proteins extracted from the mycelia of aggressive and nonaggressive strains of Ophiostoma ulmi

1986 ◽  
Vol 64 (9) ◽  
pp. 2073-2081 ◽  
Author(s):  
Robert S. Jeng
Keyword(s):  
Dutch Elm Disease ◽  
Two Dimensional ◽  
Polyacrylamide Gels ◽  
Ophiostoma Ulmi ◽  
Two Dimensional Electrophoresis ◽  
Coomassie Blue ◽  
Isoelectric Points ◽  
Additional Protein ◽  
Dimensional Electrophoresis ◽  
Electrophoresis Of Proteins

Soluble mycelial proteins from Ophiostoma ulmi (Buism.) Nannf., the causal agent of Dutch elm disease, were separated by analytical electrofocusing and two-dimensional electrophoresis in polyacrylamide gels. Results showed the aggressive and nonaggressive strains of this pathogen each had about 60 Coomassie blue stained bands having isoelectric points from 3 to 7. Both strains of this fungus had their own characteristic electrofocusing patterns. Nonaggressive isolate S116, for example, lacked two protein bands, one near the anode and one near the cathode, but it had five additional protein bands distributed from pH 4 to 6. Two-dimensional electrophoresis of total soluble proteins depicted that there were 36 proteins found to be specific for the nonaggressive isolate S116 and 12 proteins for the aggressive isolate RR2.

Linkage Analysis of Sex Determination in Bracon sp. Near hebetor (Hymenoptera: Braconidae)

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 205-212
Author(s):  
Alisha K Holloway ◽  
Michael R Strand ◽  
William C Black ◽  
Michael F Antolin
Keyword(s):  
Linkage Group ◽  
Sex Determination ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Parasitic Wasp ◽  
Specific Pattern ◽  
Diploid Males ◽  
Phenotypic Marker ◽  
Group I ◽  
Sex Locus

Abstract To test whether sex determination in the parasitic wasp Bracon sp. near hebetor (Hymenoptera: Braconidae) is based upon a single locus or multiple loci, a linkage map was constructed using random amplified polymorphic DNA (RAPD) markers. The map includes 71 RAPD markers and one phenotypic marker, blonde. Sex was scored in a manner consistent with segregation of a single “sex locus” under complementary sex determination (CSD), which is common in haplodiploid Hymenoptera. Under haplodiploidy, males arise from unfertilized haploid eggs and females develop from fertilized diploid eggs. With CSD, females are heterozygous at the sex locus; diploids that are homozygous at the sex locus become diploid males, which are usually inviable or sterile. Ten linkage groups were formed at a minimum LOD of 3.0, with one small linkage group that included the sex locus. To locate other putative quantitative trait loci (QTL) for sex determination, sex was also treated as a binary threshold character. Several QTL were found after conducting permutation tests on the data, including one on linkage group I that corresponds to the major sex locus. One other QTL of smaller effect had a segregation pattern opposite to that expected under CSD, while another putative QTL showed a female-specific pattern consistent with either a sex-differentiating gene or a sex-specific deleterious mutation. Comparisons are made between this study and the indepth studies on sex determination and sex differentiation in the closely related B. hebetor.

Linkage group I: the simultaneous estimation of recombination and interference

1976 ◽  
Vol 16 (1-5) ◽  
pp. 335-339 ◽  
Author(s):  
D.A. Meyers ◽  
P.M. Conneally ◽  
E.W. Lovrien ◽  
E. Magenis ◽  
A.D. Merritt ◽  
...  
Keyword(s):  
Linkage Group ◽  
Simultaneous Estimation ◽  
Group I

scholarly journals The occurrence of endophytic fungus Phomopsis oblonga on elms in the area of southern Bohemia

2012 ◽  
Vol 52 (No. 11) ◽  
pp. 531-535 ◽  
Author(s):  
M. Dvořák ◽  
D. Palovčíková ◽  
L. Jankovský
Keyword(s):  
Endophytic Fungus ◽  
Health Condition ◽  
Dutch Elm Disease ◽  
Mixed Forests ◽  
Ophiostoma Ulmi

The health condition of the population of elms in the region of southern Bohemiawas studied from the viewpoint of their decline, the occurrence of Dutch Elm Disease (DED) and the presence of other diseases. Of the total number of 105 elms in total 33 of them were without any symptoms of the disease or other damage. Elms regenerated quite spontaneously in the neighbourhood of mother trees and their increasing population in mixed forests is hopeful. According to macroscopic symptoms, DED was identified in 10 trees but the presence of pathogens Ophiostoma ulmi and Ophiostoma novo-ulmi was not identified in isolations. A possible reason of this observation is overgrowing the colonies by the Phomopsis oblonga mycelium. This fungus was identified in most isolations. Thus, its role requires further research.

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