Sexual agglutination in Chlamydomonas eugametos before and after cell fusion

Planta ◽  
1985 ◽  
Vol 166 (2) ◽  
pp. 234-243 ◽  
Author(s):  
A. Musgrave ◽  
P. de Wildt ◽  
F. Schuring ◽  
K. Crabbendam ◽  
H. van den Ende
Keyword(s):  
Cell Fusion ◽  
Sexual Agglutination ◽  
Chlamydomonas Eugametos ◽  
Before And After

scholarly journals SEX-LIMITED EXPRESSION OF GENE LOCI CONTROLLING FLAGELLAR MEMBRANE AGGLUTINATION IN THE CHLAMYDOMONAS MATING REACTION

Genetics ◽  
1978 ◽  
Vol 89 (2) ◽  
pp. 235-243
Author(s):  
Ursula W Goodenough ◽  
Carol Hwang ◽  
A Jane Warren
Keyword(s):  
Genetic Analysis ◽  
Cell Fusion ◽  
Mating Reaction ◽  
Sexual Agglutination ◽  
Flagellar Membrane ◽  
Mutant Strains

ABSTRACT Mutant strains of Chlamydomonas reinhardi that have lost their ability to undergo sexual agglutination via their flagellar tips have been induced to undergo zygotic cell fusion and meiosis, using a flagellar-directed antiserum. Genetic analysis of antiserum-mediated crosses involving five nonagglutinating mt  + mutant strains reveals the following: (1) None of the mutations is linked to the mt locus. (2) All of the mutations are "sex-limited," meaning that they can be carried and transmitted by, but not expressed in, mt  - cells. (3) Four of the mutations (imp-2, imp-5, imp-6, imp-7) are either allelic or closely linked to one another, with imp-8 defining a second locus.

scholarly journals Sexual Agglutination in the Unicellular Green Alga Chlamydomonas eugametos

1985 ◽  
Vol 79 (3) ◽  
pp. 740-745 ◽  
Author(s):  
Frans M. Klis ◽  
Marieke R. Samson ◽  
Egbert Touw ◽  
Alan Musgrave ◽  
Herman van den Ende
Keyword(s):  
Green Alga ◽  
Sexual Agglutination ◽  
Chlamydomonas Eugametos ◽  
Unicellular Green Alga

Transport of membrane receptors and the mechanics of sexual cell fusion in Chlamydomonas eugametos

FEBS Letters ◽  
1987 ◽  
Vol 215 (2) ◽  
pp. 323-326 ◽  
Author(s):  
Wieger Homan ◽  
Corrien Sigon ◽  
Wies van den Briel ◽  
Ron Wagter ◽  
Hans de Nobel ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Membrane Receptors ◽  
Sexual Cell ◽  
Chlamydomonas Eugametos

Sexual agglutination factor from Chlamydomonas eugametos

Planta ◽  
1981 ◽  
Vol 153 (4) ◽  
pp. 362-369 ◽  
Author(s):  
Alan Musgrave ◽  
Ed van Eijk ◽  
Ruud te Welscher ◽  
Rob Broekman ◽  
Peter Lens
Keyword(s):  
Sexual Agglutination ◽  
Chlamydomonas Eugametos

An inhibitor of cell fusion in Chlamydomonas eugametos

1978 ◽  
Vol 117 (2) ◽  
pp. 131-134 ◽  
Author(s):  
D. A. M. Mesland ◽  
H. van den Ende
Keyword(s):  
Cell Fusion ◽  
Chlamydomonas Eugametos

scholarly journals Plasma Membrane Fusion Is Specifically Impacted by the Molecular Structure of Membrane Sterols During Vegetative Development of Neurospora crassa

Genetics ◽  
2020 ◽  
Vol 216 (4) ◽  
pp. 1103-1116
Author(s):  
Martin Weichert ◽  
Stephanie Herzog ◽  
Sarah-Anne Robson ◽  
Raphael Brandt ◽  
Bert-Ewald Priegnitz ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Neurospora Crassa ◽  
Cell Fusion ◽  
Molecular Mechanisms ◽  
Ring System ◽  
Ergosterol Biosynthesis ◽  
Vegetative Development ◽  
Before And After ◽  
Sexual Fusion ◽  
Eukaryotic Organisms

Cell-to-cell fusion is crucial for the development and propagation of most eukaryotic organisms. Despite this importance, the molecular mechanisms mediating this process are only poorly understood in biological systems. In particular, the step of plasma membrane merger and the contributing proteins and physicochemical factors remain mostly unknown. Earlier studies provided the first evidence of a role of membrane sterols in cell-to-cell fusion. By characterizing different ergosterol biosynthesis mutants of the fungus Neurospora crassa, which accumulate different ergosterol precursors, we show that the structure of the sterol ring system specifically affects plasma membrane merger during the fusion of vegetative spore germlings. Genetic analyses pinpoint this defect to an event prior to engagement of the fusion machinery. Strikingly, this effect is not observed during sexual fusion, suggesting that the specific sterol precursors do not generally block membrane merger, but rather impair subcellular processes exclusively mediating fusion of vegetative cells. At a colony-wide level, the altered structure of the sterol ring system affects a subset of differentiation processes, including vegetative sporulation and steps before and after fertilization during sexual propagation. Together, these observations corroborate the notion that the accumulation of particular sterol precursors has very specific effects on defined cellular processes rather than nonspecifically disturbing membrane functioning. Given the phenotypic similarities of the ergosterol biosynthesis mutants of N. crassa during vegetative fusion and of Saccharomyces cerevisiae cells undergoing mating, our data support the idea that yeast mating is evolutionarily and mechanistically more closely related to vegetative than sexual fusion of filamentous fungi.

scholarly journals Monoclonal antibodies directed against the sexual binding site of Chlamydomonas eugametos gametes.

1988 ◽  
Vol 107 (1) ◽  
pp. 177-189 ◽  
Author(s):  
W Homan ◽  
A Musgrave ◽  
H de Nobel ◽  
R Wagter ◽  
D de Wit ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Immunofluorescence Test ◽  
Sexual Agglutination ◽  
Class A ◽  
Fab Fragments ◽  
Chlamydomonas Eugametos ◽  
Low Concentrations ◽  
Class B ◽  
Positive Class ◽  
High Concentrations

Monoclonal antibodies were raised against the mt- sexual agglutinin of Chlamydomonas eugametos gametes. Those that blocked the agglutination site were selected. They were divided into two classes dependent upon whether they gave a weak (class A) or clear positive (class B) reaction with mt- flagellar membranes in an ELISA and an indirect immunofluorescence test using glutaraldehyde-fixed mt- gametes. Class A antibodies were shown to be specific for the agglutinin in an extract of mt- gametes, based on results from immunoblotting, immunoprecipitation, affinity chromatography, and the absence of a reaction with nonagglutinable cells. Surprisingly, class A mAbs also recognized two mt+ glycoproteins, one of which is the mt+ agglutinin. Class B antibodies were shown to bind to several glycoproteins in both mt- and mt+ gametes, including the mt- agglutinin. Fab fragments from class A mAbs blocked the sexual agglutination process, but those from class B did not, even though the parent antibody did. We conclude that the class A epitope lies in or close to the agglutination site of the mt- agglutinin, whereas the class B epitope lies elsewhere on the molecule. We also conclude that the mt- agglutinin is the only component on the mt- flagellar surface directly involved in agglutination. Class A mAbs were found to elicit several reactions displayed by the mt+ agglutinin. They bound to the mt- agglutinin on gamete flagella and induced most of the reactions typical of sexual agglutination, with the exception of flagellar tip activation. None of these reactions was induced by Fab fragments. High concentrations of class A mAbs completely repressed the sexual competence of live mt- gametes, but low concentrations stimulated cell fusion.

scholarly journals RARE-CELL FUSION EVENTS BETWEEN DIPLOID AND HAPLOID STRAINS OF THE SEXUALLY AGGLUTINATIVE YEAST HANSENULA WINGEI

Genetics ◽  
1979 ◽  
Vol 93 (4) ◽  
pp. 903-916
Author(s):  
Marjorie Crandall ◽  
Joan H Caulton
Keyword(s):  
Cell Fusion ◽  
Mating Type ◽  
Low Frequency ◽  
Physiological Mechanisms ◽  
Type Locus ◽  
Sexual Agglutination ◽  
Mating Type Locus ◽  
Hansenula Wingei ◽  
Fusion Products ◽  
Cell Fusions

ABSTRACT Diploids of the yeast Hansenula wingei are nonagglutinative and do not form zygotes in mixed cultures with either sexually agglutinative haploid mating type. However, a low frequency of diploid x haploid cell fusions (about 10-3) is detectable by prototrophic selection. This frequency of rare diploid x haploid matings is not increased after the diploid culture is induced for sexual agglutination. Therefore, we conclude that genes that repress mating are different from those that repress sexual agglutination.——Six prototrophs isolated from one diploid x haploid cross had an average DNA value (¼g DNA per 108 cells) of 6.19, compared to 2.53 and 4.35 for the haploid and diploid swains, respectively. Four prototrophs were clearly cell-fusion products because they contained genes from both the diploid and the haploid partners. However, genetic analysis of the prototrophs yielded results inconsistent with triploid meiosis; all six isolates yielded a 2:2 segregation for the mating-type alleles and linked genes.——Mitotic segregation of monosomic (2n-1) cells lacking one homolog of the chromosome carrying the mating-type locus is proposed to explain the rare production of sexually active cells in the diploid cultures. Fusion between such monosomic cells and normal haploids is thought to have produced 3n-1 cells, disomic for the chromosome carrying the mating-type locus. We conclude that in the diploid strain we studied, the physiological mechanisms repressing sexual agglutination and conjugation function efficiently, but events occurring during mitosis lead to a low frequency of genetically altered cells in the population.

Deformation Replication

1970 ◽  
Vol 28 ◽  
pp. 280-281
Author(s):  
J. Temple Black
Keyword(s):  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Rake Face ◽  
Orthogonal Machining ◽  
Aluminum Chips ◽  
Before And After ◽  
Materials Used ◽  
Glass Knife ◽  
Very High

Tool materials used in ultramicrotomy are glass, developed by Latta and Hartmann (1) and diamond, introduced by Fernandez-Moran (2). While diamonds produce more good sections per knife edge than glass, they are expensive; require careful mounting and handling; and are time consuming to clean before and after usage, purchase from vendors (3-6 months waiting time), and regrind. Glass offers an easily accessible, inexpensive material ($0.04 per knife) with very high compressive strength (3) that can be employed in microtomy of metals (4) as well as biological materials. When the orthogonal machining process is being studied, glass offers additional advantages. Sections of metal or plastic can be dried down on the rake face, coated with Au-Pd, and examined directly in the SEM with no additional handling (5). Figure 1 shows aluminum chips microtomed with a 75° glass knife at a cutting speed of 1 mm/sec with a depth of cut of 1000 Å lying on the rake face of the knife.

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