Cytological Significance of the Nature of Sexual Fusion in Hymenomycetes

Nature ◽  
1935 ◽  
Vol 136 (3448) ◽  
pp. 873-873
Author(s):  
S. R. BOSE
Keyword(s):  
Sexual Fusion

Babesia: Sexual Fusion

2016 ◽  
pp. 275-275
Author(s):  
Heinz Mehlhorn
Keyword(s):  
Sexual Fusion

scholarly journals A Test for Sexual Fusion in Bacteria1

1942 ◽  
Vol 44 (5) ◽  
pp. 551-554 ◽  
Author(s):  
John W. Gowen ◽  
Ralph E. Lincoln
Keyword(s):  
Sexual Fusion

Generic Circumscription in the Family Ectocarpaceae (Phaeophyceae)

1978 ◽  
Vol 58 (2) ◽  
pp. 517-525 ◽  
Author(s):  
G. Russell ◽  
D. Garbary
Keyword(s):  
Cell Division ◽  
Structural Modification ◽  
Active Cell ◽  
Horizontal Branch ◽  
Vegetative Cells ◽  
Sustained Activity ◽  
Cell Divisions ◽  
Branch System ◽  
The Family ◽  
Sexual Fusion

The family Ectocarpaceae currently contains the simplest, and probably also the most primitive, members of the Phaeophyceae. The thallus form of every species is a heterotrichous filament with little or no structural modification. Some species may possess quite extensive cortication of axial filaments by adventitious rhizoids but advanced pseudoparenchyma is never formed. Periclinal cell divisions within filaments have also been reported, particularly in the course of sporangium development, but true parenchyma is unknown. Growth of the erect system of filaments is diffuse, for although intercalary sites of relatively active cell division may sometimes be observed, these lack the permanence of position and sustained activity of true intercalary meristems. The growth of the horizontal branch system is probably mainly apical, but is also too diffuse to be considered meristematic. Sporangia and gametangia are formed from vegetative cells and occur either as intercalary structures within filaments or as modified branch apices. Sexual fusion of gametes may be isogamous or anisogamous.

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.

Environmental control of gametogenesis in Laminaria saccharina. II. Correlation of nitrate and phosphate concentrations with gametogenesis and selected metabolites

1973 ◽  
Vol 51 (5) ◽  
pp. 829-839 ◽  
Author(s):  
Stephen I. C. Hsiao ◽  
Louis D. Druehl
Keyword(s):  
Female Gametophyte ◽  
Environmental Control ◽  
Male Gametophyte ◽  
Axenic Culture ◽  
Nutrient Concentrations ◽  
Growth Morphology ◽  
Laminaria Saccharina ◽  
Synthetic Seawater ◽  
Sexual Fusion ◽  
Seawater Medium

The gametophyte growth, morphology, gametogenesis, and metabolites of Laminaria saccharina (L.) Lamouroux were studied in different cyncentrations of nitrate and phosphate in axenic culture, using a synthetic seawater medium under optimal light and temperature conditions.Nitrate and phosphate were required for the various stages of gametophyte development and gametogenesis. Under nitrate and phosphate concentrations optimal for growth and gametogenesis, maximum quantities of DNA, RNA, protein, and carbohydrate, and low quantities of lipid were produced. Further, nutrient concentrations which gave rise to the greatest fertility also gave rise to the highest ratios of RNA/DNA and protein/RNA.Antheridial production occurred over a wider range of nitrate and phosphate concentrations than oogonial production. Further, percentage fertility was greater for the male gametophyte. This indicated that the female gametophyte was the limiting agent in sexual fusion.

Evidence for sexual fusion and recombination in the dinoflagellate Crypthecodinium (Gyrodinium) cohnii

Nature ◽  
1974 ◽  
Vol 250 (5465) ◽  
pp. 435-436 ◽  
Author(s):  
CARL A. BEAM ◽  
MARION HIMES
Keyword(s):  
Sexual Fusion

scholarly journals A GENE, ALCA, AFFECTING THE LIFE CYCLE FORM EXPRESSED IN PHYSARUM POLYCEPHALUM

Genetics ◽  
1982 ◽  
Vol 101 (1) ◽  
pp. 35-55
Author(s):  
Christine L Truitt ◽  
Charles S Hoffman ◽  
Charles E Holt
Keyword(s):  
Growth Rate ◽  
Life Cycle ◽  
Physarum Polycephalum ◽  
Elevated Temperatures ◽  
Single Gene ◽  
Critical Density ◽  
Complementation Group ◽  
The Other ◽  
Wild Type ◽  
Sexual Fusion

ABSTRACT The usual sequence of forms in the Physarum polycephalum life cycle is plasmodium–spore–amoeba–plasmodium. So-called "amoebaless life cycle" or alc mutants of this Myxomycete undergo a simplified plasmodium–spore–plasmodium life cycle. We have analyzed three independently isolated alc mutants and found in each case that the failure of the spores to give rise to amoebae is due to a recessive Mendelian allele. The three mutations are tightly linked to one another and belong to a single complementation group, alcA. The mutations are pleiotropic, not only interfering with the establishment of the amoebal form at spore germination, but also affecting the phenotype of alc amoebae, which occasionally arise from alc spores. The alc amoebae (1) grow more slowly than wild type, particularly at elevated temperatures; (2) tend to transform directly into plasmodia, circumventing the sexual fusion of amoebae that usually accompanies plasmodium formation; and (3) form plasmodia by the sexual mechanism less efficiently than wild-type amoebae. The various effects of an alc mutation seem to derive from mutation of a single gene, since reversion for one effect is always accompanied by reversion for the other effects. Moreover, a mutation, aptA1, that blocks direct plasmodium formation by alcA amoebae, also increases their growth rate to near normal. The manner of plasmodium formation in alcA strains differs significantly from that in another class of mutants, the gad mutants. Unlike gad amoebae, alcA amoebae need not reach a critical density in order to differentiate directly into plasmodia and do not respond to the extracellular inducer of differentiation. In addition, alcA differentiation is not prevented by a mutation, npfA1, that blocks direct differentiation by most gad amoebae.

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