A genetic study on Gracilaria sjoestedtii

1988 ◽  
Vol 66 (10) ◽  
pp. 2022-2026 ◽  
Author(s):  
Xuecheng Zhang ◽  
John P. van der Meer
Keyword(s):  
Chromosome Number ◽  
Genetic Study ◽  
Maternal Inheritance ◽  
Intragenic Recombination ◽  
Wild Type ◽  
Multiple Alleles ◽  
Wild Type Clone ◽  
Nuclear Mutations ◽  
Diploid Gametes ◽  
Mendelian Analysis

In the present study on Gracilaria sjoestedtii, 41 mutants (40 pigmentation and 1 morphological) were isolated. These were characterized in a Mendelian analysis, which showed that 26 of the pigmentation variants are recessive nuclear mutations. The remaining 14 are cytoplasmic mutants having maternal inheritance and no detectable transmission through spermatia. A partial complementation analysis identified seven cistrons among the nuclear pigmentation mutants. Multiple alleles were encountered at five loci and apparent intragenic recombination was observed. No linkage between cistrons was found in recombination tests conducted thus far. Mitotic recombination leading to diploid gametes on tetrasporophytes was observed and used to construct triploid tetrasporophytes. The chromosome number of a wild-type clone of G. sjoestedtii was determined at meiosis as n = 29–30. Trivalent chromosomes were observed during meiosis in tetrasporophytes obtained by crossing female plants with tetrasporophytes. In culture tanks with flowing seawater, female gametophytes grew faster and appeared more suitable for vegetative propagation than male gametophytes and tetrasporophytes.

Genetics of Gracilaria tikvahiae (Rhodophyceae). VI. Complementation and linkage analysis of pigmentation mutants

1979 ◽  
Vol 57 (1) ◽  
pp. 64-68 ◽  
Author(s):  
John P. van der Meer
Keyword(s):  
Linkage Analysis ◽  
Linkage Map ◽  
Intragenic Recombination ◽  
Wild Type ◽  
Multiple Alleles ◽  
Gracilaria Tikvahiae

Pigmentation mutants of Gracilaria tikvahiae that differed in several ways from the brownish colour of wild type were characterized genetically by complementation and recombination. Thirty cistrons with multiple alleles at several loci were identified. Many of the cistrons were genetically linked with one or more other loci, and the beginnings of a linkage map is presented. Examples of intragenic recombination between noncomplementing mutants were also encountered.

ON THE IDENTIFICATION OF THE ROSY LOCUS DNA IN DROSOPHILA MELANOGASTER: INTRAGENIC RECOMBINATION MAPPING OF MUTATIONS ASSOCIATED WITH INSERTIONS AND DELETIONS

Genetics ◽  
1986 ◽  
Vol 112 (4) ◽  
pp. 755-767
Author(s):  
S H Clark ◽  
M McCarron ◽  
C Love ◽  
A Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Large Scale ◽  
Conclusive Evidence ◽  
Hybrid Dysgenesis ◽  
Intragenic Recombination ◽  
Wild Type ◽  
Structural Element ◽  
Insertions And Deletions ◽  
Recombination Mapping

ABSTRACT DNA extracts of several rosy-mutation-bearing strains were associated with large insertions and deletions in a defined region of the molecular map believed to include the rosy locus DNA. Large-scale, intragenic mapping experiments were carried out that localized these mutations within the boundaries of the previously defined rosy locus structural element. Molecular characterization of the wild-type recombinants provides conclusive evidence that the rosy locus DNA is localized to the DNA segment marked by these lesions.—One of the mutations, ry  2101, arose from a P-M hybrid dysgenesis experiment and is associated with a copia insertion. Experiments are described which suggest that copia mobilizes in response to P-M hybrid dysgenesis.—Relevance of the data to recombination in higher organisms is considered.

scholarly journals Cytoplasmic mutations isolated from protoplasts ofPodospora anserina

1975 ◽  
Vol 25 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Léon Belcour
Keyword(s):  
Maternal Inheritance ◽  
Podospora Anserina ◽  
Wild Type ◽  
Stage Of Development ◽  
Type Factor ◽  
Type Strains

SUMMARYSorting out of cytoplasm determinants can be achieved inPodospora anserinaby the use of protoplasts. In this way four cytoplasmic mutations have been isolated. These mutations affect a precise stage of development of the fungus. In crosses with wild-type strains, the mutants show maternal inheritance when no cytoplasmic contact precedes fertilization. However, when cytoplasmic mixing occurs before fertilization, the cytoplasmic wild-type factor shows dominant and/or suppressive properties over the mutant factor.

scholarly journals Analysis of the structural features of the C-terminus of GLUT1 that are required for transport catalytic activity

1995 ◽  
Vol 311 (2) ◽  
pp. 699-704 ◽  
Author(s):  
A Muraoka ◽  
M Hashiramoto ◽  
A E Clark ◽  
L C Edwards ◽  
H Sakura ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glucose Transport ◽  
Cytochalasin B ◽  
Point Mutations ◽  
Chinese Hamster ◽  
Structural Features ◽  
Transport Activity ◽  
Wild Type ◽  
C Terminus ◽  
Wild Type Clone

C-terminally truncated and mutated forms of GLUT1 have been constructed to determine the minimum structure at the C-terminus required for glucose transport activity and ligand binding at the outer and inner binding sites. Four truncated mutants have been constructed (CTD24 to CTD27) in which 24 to 27 amino acids are deleted. In addition, point substitutions of R468-->L, F467-->L and G466-->E have been produced. Chinese hamster ovary clones which were transfected with these mutant GLUT1s were shown, by Western blotting and cell-surface carbohydrate labelling, to have expression levels which were comparable with the wild-type clone. Wild-type levels of 2-deoxy-D-glucose transport activity were retained only in the clone transfected with the construct in which 24 amino acids were deleted (CTD24). The CTD25, CTD26 and CTD27 clones showed markedly reduced transport activity. From a kinetic comparison of the CTD24 and CTD26 clones it was found that the reduced transport was mainly associated with a reduced Vmax. value for 2-deoxy-D-glucose uptake but with a slight lowering of the Km. These data establish that the 24 amino acids at the C-terminus of GLUT1 are not required for the transport catalysis. However, the point mutations of F467L and G466E (26 and 27 residues from the C-terminus) did not significantly perturb the kinetics of 2-deoxy-D-glucose transport. The substitution of R468L produced a slight, but significant, lowering of the Km. The ability of the truncated GLUt1s to bind the exofacial ligand, 2-N-4-(1-zai-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(D-mannos- 4-yl-oxy) -2-propylamine (ATB-BMPA), and the endofacial ligand, cytochalasin B, were assessed by photolabelling procedures. The ability to bind ATB-BMPA was retained only in the CTD24 truncated mutant and was reduced to levels comparable with those of the non-transfected clone in the other mutant clones. Cytochalasin B labelling was unimpaired in all four mutated GLUT1s. These data establish that a minimum structure at the C-terminus of GLUT1, which is required for the conformational change to expose the exofacial site, includes amino acids at positions Phe-467 and Arg-468; however, these amino acids are not individually essential.

Effects of temperature and tissue age on gel strength and composition of agar from Gracilaria tikvahiae (Rhodophyceae)

1984 ◽  
Vol 62 (8) ◽  
pp. 1665-1670 ◽  
Author(s):  
James S. Craigie ◽  
Zong C. Wen
Keyword(s):  
Gel Strength ◽  
Wild Type ◽  
Gracilaria Tikvahiae ◽  
Morphological Mutants ◽  
Wild Type Clone ◽  
Effects Of Temperature ◽  
Lateral Branches ◽  
Increasing Temperature ◽  
Strong Inverse Relationship ◽  
Galactose Content

Agars were prepared from a wild type and two morphological mutants of Gracilaria tikvahiae grown at 17, 22, and 27 °C, and from apical segments, main axis segments, and lateral branches of the wild type clone MP-2 grown at 17 and 27 °C. The yield of native agar was 9–11% from the young parts and 19–23% from the most mature parts of the MP-2 thallus. The gel strengths of alkali-modified agars showed a strong inverse relationship with increasing temperature of growth in each of the three clones examined. The modified agar produced from plants grown at high temperature contained more sulfate and less 3,6-anhydro-L-galactose than agars produced at lower temperatures. The increase in 4-O-methyl-L-galactose content of the agars as the growth temperature increased was especially marked. Dissection experiments on clone MP-2 showed that agar with the maximum gel strength and 3,6-anhydro-L-galactose content and the minimum sulfate and 4-O-methyl-L-galactose content was produced at low temperature by apical segments and young lateral branches. The poorest quality agar was prepared from mature segments of the thallus, especially those grown at high temperatures. Agars prepared from mature parts of the thallus were greatly enriched in 4-O-methyl-L-galactose, which reached 8.8% of the weight of the agar at 27 °C. Changes in 6-O-methyl-D-galactose were smaller, but this sugar was lowest in agar prepared from young tissues of plants grown at 17 °C.

scholarly journals Shift and adapt: the costs and benefits of karyotype variations

2015 ◽  
Author(s):  
Aleeza C Gerstein ◽  
Judith Berman
Keyword(s):  
Chromosome Number ◽  
Base Pair ◽  
Homologous Chromosome ◽  
Molecular Mechanisms ◽  
Costs And Benefits ◽  
Wild Type ◽  
Genomic Variants ◽  
Karyotypic Variation ◽  
Type Chromosome ◽  
Pair Level

Variation is the spice of life or, in the case of evolution, variation is the necessary material on which selection can act to enable adaptation. Karyotypic variation in ploidy (the number of homologous chromosome sets) and aneuploidy (imbalance in the number of chromosomes) are fundamentally different than other types of genomic variants. Karyotypic variation emerges through different molecular mechanisms than other mutational events, and unlike mutations that alter the genome at the base pair level, rapid reversion to the wild type chromosome number is often possible. Although karyotypic variation has long been noted and discussed by biologists, interest in the importance of karyotypic variants in evolutionary processes has spiked in recent years, and much remains to be discovered about how karyotypic variants are produced and subsequently selected.

RAD52-INDEPENDENT MITOTIC GENE CONVERSION IN SACCHAROMYCES CEREVISIAE FREQUENTLY RESULTS IN CHROMOSOMAL LOSS

Genetics ◽  
1985 ◽  
Vol 111 (1) ◽  
pp. 7-22
Author(s):  
James E Haber ◽  
Mark Hearn
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Mitotic Recombination ◽  
Gene Conversion Event ◽  
Intragenic Recombination ◽  
Wild Type ◽  
Conversion Event ◽  
Chromosomal Loss ◽  
Mitotic Gene Conversion ◽  
Striking Effect

ABSTRACT We have examined spontaneous, interchromosomal mitotic recombination events between his4 alleles in both Rad+ and rad52 strains of Saccharomyces cerevisiae. In Rad+ strains, 74% of the His+ prototrophs resulted from gene conversion events without exchange of flanking markers. In diploids homozygous for the rad52-1 mutation, the frequency of His+ prototroph formation was less than 5% of the wild-type value, and more than 80% of the gene conversion events were accompanied by an exchange of flanking markers. Most of the rad52 intragenic recombination events arose by gene conversion accompanied by an exchange of flanking markers and not by a simple reciprocal exchange between the his4A and his4C alleles. There were also profound effects on the kinds of recombinant products that were recovered. The most striking effect was that RAD52-independent mitotic recombination frequently results in the loss of one of the two chromosomes participating in the gene conversion event.

Defective processing and expression of thiazide-sensitive Na-Cl cotransporter as a cause of Gitelman’s syndrome

1999 ◽  
Vol 277 (4) ◽  
pp. F643-F649 ◽  
Author(s):  
Shanti Kunchaparty ◽  
Matthew Palcso ◽  
Jennifer Berkman ◽  
Heino Velázquez ◽  
Gary V. Desir ◽  
...  
Keyword(s):  
Autosomal Recessive Disorder ◽  
Functional Expression ◽  
Transport Protein ◽  
Wild Type ◽  
Western Blots ◽  
Cytoplasmic Staining ◽  
Salt Wasting ◽  
Membrane Staining ◽  
Gitelman's Syndrome ◽  
Wild Type Clone

Gitelman’s syndrome is an autosomal recessive disorder of salt wasting and hypokalemia caused by mutations in the thiazide-sensitive Na-Cl cotransporter. To investigate the pathogenesis of Gitelman’s syndrome, eight disease mutations were introduced into the mouse thiazide-sensitive Na-Cl cotransporter and studied by functional expression in Xenopus oocytes. Sodium uptake into oocytes that expressed the wild-type clone was more than sevenfold greater than uptake into control oocytes. Uptake into oocytes that expressed the mutated transporters was not different from control. Hydrochlorothiazide reduced Na uptake by oocytes expressing the wild-type gene to control values but had no effect on oocytes expressing the mutant clones. Western blots of oocytes injected with the wild-type clone showed bands representing glycosylated (125 kDa) and unglycosylated (110 kDa) forms of the transport protein. Immunoblot of oocytes expressing the mutated clones showed only the unglycosylated protein, indicating that protein processing was disrupted. Immunocytochemistry with an antibody against the transport protein showed intense membrane staining of oocytes expressing the wild-type protein. Membrane staining was completely absent from oocytes expressing mNCCR948X; instead, diffuse cytoplasmic staining was evident. In summary, the results show that several mutations that cause Gitelman’s syndrome are nonfunctional because the mutant thiazide-sensitive Na-Cl cotransporter is not processed normally, probably activating the “quality control” mechanism of the endoplasmic reticulum.

scholarly journals Tightly centromere-linked gene (SPO15) essential for meiosis in the yeast Saccharomyces cerevisiae

1986 ◽  
Vol 6 (1) ◽  
pp. 158-167
Author(s):  
E Yeh ◽  
J Carbon ◽  
K Bloom
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Transcriptional Activity ◽  
Intragenic Recombination ◽  
Wild Type ◽  
Base Pairs ◽  
Yeast Saccharomyces Cerevisiae ◽  
Linked Gene ◽  
Mutant Cells

We used DNA fragments from the centromere regions of yeast (Saccharomyces cerevisiae) chromosomes III and XI to examine the transcriptional activity within this chromosomal domain. DNA transcripts were found 200 to 300 base pairs from the 250-base-pair centromere core and lie within an ordered chromatin array. No transcripts were detected from the functional centromere region. We examined the cellular function of one of these tightly centromere-linked transcripts. (CEN11)L, by disrupting the coding sequences in vivo and analyzing the phenotype of the mutant yeast cell. Diploids heterozygous for the (CEN11)L disruption sporulated at wild-type levels, and the absence of the (CEN11)L gene product had no effect on the viability or mitotic growth of haploid cells. Diploids homozygous for the (CEN11)L disruption were unable to sporulate when induced by the appropriate nutritional cues. The mutant cells were competent for intragenic recombination and appeared to be blocked at the mononucleate stage. The temporal ordering of (CEN11)L function with respect to the sporulation mutant spo13 suggests that the (CEN11)L gene product may be required at both the first and second meiotic cell divisions. This new sporulation gene has been termed SPO15.

scholarly journals Genetic Instability of the Global Regulator agrExplains the Phenotype of the xpr Mutation inStaphylococcus aureus KSI9051

1998 ◽  
Vol 180 (10) ◽  
pp. 2609-2615 ◽  
Author(s):  
Peter J. McNamara ◽  
John J. Iandolo
Keyword(s):  
Cell Surface ◽  
Genetic Background ◽  
Extracellular Proteins ◽  
Specific Gene ◽  
Wild Type ◽  
Global Regulator ◽  
Erythromycin Resistance ◽  
Aberrant Expression ◽  
Wild Type Clone ◽  
The Stability

ABSTRACT Staphylococcus aureus KSI9051 has a complex mutation that was associated with the aberrant expression of cell surface and extracellular proteins (M. S. Smeltzer, M. E. Hart, and J. J. Iandolo, J. Bacteriol. 61:919–925, 1993). This mutation was named xpr, although no specific gene was identified. Here this mutation is referred to as Δ1058::Tn551. In this study, we show that in strain KSI9051, the Δ1058::Tn551 mutation occurred coincidentally with a frameshift in agrC that is expected to truncate the sensor component of the known staphylococcal global regulatory locus agr. Remarkably, pleiotropic mutations affecting cell surface and extracellular proteins are generated at frequencies approaching 50% upon the transduction of erythromycin resistance (Emr) encoded by Δ1058::Tn551 from S. aureus KSI905 back to its parental strain, S6C. Three independent isolates created in the manner of KSI9051 contained mutations within agrC. Each isolate had different mutations, suggesting that the transduction of Emr encoded by Δ1058::Tn551 affects the stability ofagrC in S6C. In similar experiments with strains from anS. aureus 8325 genetic background, a mutant AgrC phenotype could not be isolated, implying that strain S6 has aberrant genetic behavior. A comparison of the nucleotide sequences of AgrC from several strains revealed seven errors in the GenBank entry for agr(X52543 ); these data were confirmed with plasmid pRN6650, the original wild-type clone of agr.

Sign in / Sign up

Export Citation Format

Share Document