Search results for "Mutant"
showing 10 items of 670 documents
Genetic location and biochemical characterization of eye-colour mutants from natural populations of Drosophila melanogaster
1990
From six captures of Drosophila melanogaster carried out in three different habitats (cellar, vineyard, and pinewood) in two different seasons of the year (spring and autumn), 60 eye-colour mutations were isolated, which were reduced to 29 loci by means of allelism tests within and between populations. Forty-five of these mutations were analyzed genetically and biochemically; of these 33 turned out to be previously described mutants and mapped to a total of 17 loci. Twelve new mutants were discovered and they mapped to 12 new loci, distributed on chromosomes X, II, and III. The eye-colour mutants show large effects on the red and brown pigments. The high variability of the eye-colour loci …
Unmasking frequency-dependent selection in tri-cultures of Drosophila melanogaster.
1989
Larval-to-adult viability was measured for three strains of Drosophila melanogaster: a wild strain and two eye colour mutant strains (cardinal and sepia) starting from seventy different genotypic compositions. Analyses of a sub-set of the data (not considering all genotypic frequencies) demonstrate frequency-dependence in the three strains. These results suggest that in this experiment, frequency-dependent selection may be masked by other selective forces, only being apparent when specific analyses are carried out.
Isolation of theMNN9gene ofYarrowia lipolytica(YlMNN9) and phenotype analysis of a mutantylmnn9Δ strain
2003
In this work we describe the isolation of the Yarrowia lipolytica homologue of Saccharomyces cerevisiae MNN9 gene, which we have named YlMNN9, and the phenotype analysis of a Y. lipolytica strain containing the disrupted YlMNN9 allele. YlMNN9 was cloned using degenerate consensus oligonucleotides to generate specific probes that were in turn used to screen mini-gene libraries. The gene is defined by a 1014 bp ORF predicted to encode a protein 337 amino acids long that shares significant homology with the Mnn9ps of S. cerevisiae, Candida albicans and Hansenula polymorpha, including a putative N-terminal transmembrane domain. Disruption of YlMNN9 leads to phenotypes such as resistance to sodi…
Complementation among developmental mutants in Aspergillus nidulans.
1973
In heterokaryons between pairs of aconidial mutants of Aspergillus nidulans one of the component strains usually shows a striking prevalance in the contribution to the conidial crop. By assuming that the prevailing strain is blocked earlier and the succumbent one later in the process of differentiation, a series of mutations can be arranged in a consistent order. Some mutant strains do not fit the scheme exactly but show a general tendency to be succumbent to “early” mutants and prevalent over the “late” ones. A criterion for arraying genes involved in differentiation according to the order of their physiological action is proposed.
Interactions between the yeast mitochondrial and nuclear genomes: isogenic suppressive and hypersuppressive petites differ in their resistance to the…
1990
In a previous paper we have shown that the alkaloid lycorine inhibits growth of rho+, mit- and rho-, strains of Saccharomyces cerevisiae, whereas strains devoid of mitochondrial DNA (rho degrees) are resistant to more than 200 micrograms/ml of the alkaloid. In this report we show that hypersuppressive petites are almost as resistant as rho degrees mutants, whereas isogenic rho- petites, which have retained longer segments of the genome, are sensitive to the drug.
Adventitious bud formation on isolated leaves and its significance for mutation breeding
1968
Since a mutation is a unicellular event, irradiation of a multicellular meristem results in the so-called diplontic selection. This competition between the mutated cell and the surrounding non-mutated cells is often lost by the mutated cell, causing a low frequency of mutated plants and a narrow mutation spectrum. When a mutated cell survives, chimeras are automatically formed because most apices consist of a number of fairly independent groups of cell layers. Such an undesirable situation can be improved by growing complete plants from only one cell, resulting in a high frequency of solid, non-chimeral mutants and a wide mutation spectrum. Many plant species can be stimulated to form adven…
Epistasis between new mutations and genetic background and a test of genetic canalization.
2001
The importance for fitness of epistatic interactions among mutations is poorly known, yet epistasis can exert important effects on the dynamics of evolving populations. We showed previously that epistatic interactions are common between pairs of random insertion mutations in the bacterium Escherichia coli. In this paper, we examine interactions between these mutations and other mutations by transducing each of twelve insertion mutations into two genetic backgrounds, one ancestral and the other having evolved in, and adapted to, a defined laboratory environment for 10,000 generations. To assess the effect of the mutation on fitness, we allowed each mutant to compete against its unmutated cou…
Intermediate Filament Diseases: Desminopathy
2008
Desminopathy is one of the most common intermediate filament human disorders associated with mutations in closely interacting proteins, desmin and alphaB-crystallin. The inheritance pattern in familial desminopathy is characterized as autosomal dominant or autosomal recessive, but many cases have no family history. At least some and likely most sporadic desminopathy cases are associated with de novo DES mutations. The age of disease onset and rate of progression may vary depending on the type of inheritance and location of the causative mutation. Typically, the illness presents with lower and later upper limb muscle weakness slowly spreading to involve truncal, neck-flexor, facial and bulba…
Molecules and Morphology, Phylogenetics and Genetics
1994
Various explanations can be offered for the incongruence between phylogenetic hypotheses resulting from morphological and molecular data sets. Of these, the possibility that incongruence may result from the mutation of major morphogenetic genes leading to dramatic morphological divergence unaccompanied by equivalent change of the phylogenetic marker molecule(s) used is discussed in detail. As evidence for this hypothesis, several examples for such incongruence are surveyed. It seems possible that in many cases the genetic basis of the morphological characters responsible for the incongruence found may be simple, and that the genes involved may be homologous to genes known from mutant system…
Conserved and newly acquired roles of PIF1 homologs in tomato (Solanum lycopersicum)
2021
ABSTRACTPHYTOCHROME INTERACTING FACTORS (PIFs) are transcription factors that interact with the photoreceptors phytochromes and integrate multiple signaling pathways related to light, temperature, defense and hormone responses. PIFs have been extensively studied inArabidopsis thaliana, but less is known about their roles in other species. Here, we investigate the role of the two homologs of PIF1 found in tomato (Solanum lycopersicum), namely PIF1a and PIF1b. Analysis of gene expression showed very different patterns, indicating a potential evolutionary divergence in their roles. At the protein level, light regulated the stability of PIF1a, but not PIF1b, further supporting a functional dive…