PubMed Health⌕ Search

Biomedical subjects

A M Srb

Publications and source records attributed to A M Srb.

At least 19 recordsLinked to original sources
PubMed1990

G. W. Beadle.

Explore the source record for details and available documents.

Genetics↗
PubMed1983

Two-dimensional electrophoresis of plasma membranes, showing differences among wild-type and abnormal ascospore mutant strains of Neurospora crassa.

Plasma membranes isolated from vegetative cultures of wild-type Neurospora crassa were analyzed by two-dimensional electrophoresis, followed by staining with silver nitrate to visualize proteins and fluorescein-labeled concanavalin A to visualize glycosylated subunits. Mycelial plasma membranes from strains carrying mutations affecting ascospores were also analyzed. Two of the mutant strains were shown to have aberrant two-dimensional membrane subunit patterns. The correlation of these abnormalities with the known electron microscopic evidence for aberrations of their ascospore-delimiting membrane during ascospore genesis is discussed.

Cell Membrane↗
PubMed1978

Molecular alteration in a Neurospora crassa morphological mutant and its phenocopy.

A procedure using ion exchange chromatography has been developed to detect alterations in a polysaccharide produced by Neurospora crassa. The polysaccharide, isolated from medium that has supported the growth of a culture, is highly responsive to the 3-methyl-2-benzothiazolinone hydrazone assay, indicating a high hexosamine content. The substance elaborated by wild-type N. crassa can be fractionated into two components that appear by rechromatography to be closely related. When isolated from mutants of the peak (pk) locus, the corresponding polysaccharide cannot be resolved into two components. Instead, a single component is consistently found. This variant chromatographic pattern cosegregates with morphological effects of the pk allele after crosses with the wild type. The polysaccharide isolated from a wild-type culture that has been induced by sorbose to phenocopy the hyphal characteristics of pk mutants elutes from the ion exchange column in a manner similar to the corresponding polysaccharide from the pk mutants.

Genotype↗
PubMed1977

Occurrence of a major protein associated with fruiting body development in Neurospora and related Ascomycetes.

Electrophoretic and immunological analysis of fruiting body (perithecial) extracts demonstrates the occurrence of a major phase-specific perithecial protein in all Neurospora species and in the closely related Gelasinospora cerealis and Sordariafimicola. The perithecial proteins from these different species fall into a number of groups with different electrophoretic mobilities. They appear to be immunologically closely related but not identical to one another even within the same genus, with only partial identity exhibited between the heterothallic and pseudohomothallic Neurospora on the one hand and the homothallic Neurospora on the other hand. In immunological analysis of fruiting body extracts of the other Ascomycetes, Podospora anserina, Cochliobolus maydis, and Aspergillus nidulans, and of ascus extracts of Saccharomyces cerevisiae, no crossreaction with the Neurospora perithecial protein was found.

Ascomycota↗
PubMed1973

Genetically related protein variants specifically associated with fruiting body maturation in Neurospora.

Electrophoretic analysis of fruiting body extracts from Neurospora reveals a characteristic protein, apparently absent in vegetative structures and ascospores, and which increases markedly in relative concentration after fertilization. Different wild-type species and strains studied have electrophoretic variants of this protein, two of which are shown to be controlled by members of an allelie pair.

Electrophoresis, Polyacrylamide Gel↗
PubMed1972

Dominance modifiers in neurospora crassa: phenocopy selection and influence of certain ascus mutants.

When homozygous in zygotes, mutant alleles at the peak locus in linkage group V of Neurospora crassa initiate aberrant asci that are nonlinear, in contrast to the linear asci characteristic of wild type. Most mutant alleles are recessive, inasmuch as crosses of the mutant strains with wild type give linear asci. However, five different mutant alleles, when heterozygous with the wild-type allele, act in varying degrees as zygote dominants, initiating both linear and nonlinear asci, the relative proportions depending on the allele. Five modifiers that act on the dominance relationships of at least one of the five possible heterozygotes of a dominant peak and its wild-type allele have been characterized, four of them having been obtained by selection directed against a phenocopy of these mutants induced by treatment of wild type with l-sorbose. The pattern of modifier specificity observed among the various dominant peak heterozygotes indicates that the phenotypic effects are produced by a complex relationship between the modifiers and the dominant peak alleles in relation to their wild-type allele. In all but two cases the direction of modification, where present, is towards decreasing the dominance of the mutant allele in the heterozygote, evidenced by an increase in the percentage of linear asci when compared with control data. The modifiers exert their maximum modification when they themselves are heterozygous with their wild-type alleles and when the dominant peak allele is heterozygous with its wild-type allele. No modification occurs when heterozygous modifiers are included in zygotes homozygous for a dominant peak allele, reinforcing the notion that the modifiers act on the dominance relationship existent between a dominant peak allele and its wild-type allele, rather than influencing some activity of the mutant allele itself. The modifiers have no detectable effect of their own on ascus morphology, since homozygous modifier zygotes initiate entirely linear asci when only wild-type alleles of peak are present in the zygotes. Their only detectable effect, other than dominance modification, appears to be in conferring sorbose resistance to the mycelium. The modifiers are unlinked to the peak locus, and, except for two of them, they are nonallelic.

Crosses, Genetic↗