Pronuclear migration, swelling, and fusion during sexual development in Dictyostelium discoideum

1987 ◽  
Vol 33 (12) ◽  
pp. 1046-1049 ◽  
Author(s):  
David R. McConachie ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Mating Type ◽  
Sexual Development ◽  
Significant Relationship ◽  
Giant Cells ◽  
Mixed Mating ◽  
Binucleate Cells ◽  
Ultrastructural Studies

In mixed mating type cultures (strains NC4 × V12) of Dictyostelium discoideum, gametes fuse to produce binucleate cells which differentiate into zygote giant cells. As pronuclei move together their volumes increase dramatically. Measurements of pronuclear volumes revealed that there is a direct, linear, and statistically significant relationship between pronuclear size and proximity. Juxtaposition of the swollen pronuclei is followed by their fusion. Ultrastructural studies indicate that pronuclear fusion involves intact pronuclear envelopes.

Phagocytic specificity during sexual development in Dictyostelium discoideum

1986 ◽  
Vol 32 (2) ◽  
pp. 79-82 ◽  
Author(s):  
Keith E. Lewis ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Concanavalin A ◽  
Sexual Development ◽  
Wheat Germ ◽  
Giant Cells ◽  
Inhibitory Effect ◽  
Sexual Cycle ◽  
Type I ◽  
Further Development ◽  
Type Receptor

During the sexual cycle of Dictyostelium discoideum, zygote giant cells develop and serve as foci for further development by chemoattracting and cannibalizing hundreds of local amoebae. Previous work has shown that the phagocytic process bears similarities to and differences from asexual endocytosis. In the present study, sexual phagocytosis in D. discoideum was found to be species and developmental stage specific. It was inhibited selectively by glucose and concanavalin A. Although a partial, inhibitory effect of mannose on phagocytosis was not statistically significant, alpha-methylmannosamine, like alpha-methyl-glucose, significantly restored the phagocytic competence of giant cells treated with concanavalin A. Other sugars (N-acetyl glucosamine, N-acetylgalactosamine, and galactose) and lectins (wheat germ agglutinin, Ulex europus type I, and Ricinis communis agglutinin type I) had no significant effect on sexual phagocytosis. Together these data indicate that a glucose-type receptor is involved in selective uptake of D. discoideum amoebae by giant cells.

Zygote giant cell differentiation in Dictyostelium discoideum: biochemical markers of specific stages of sexual development

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1200-1208 ◽  
Author(s):  
Darren D. Browning ◽  
Keith E. Lewis ◽  
Danton H. O'Day
Keyword(s):  
Alkaline Phosphatase ◽  
Cell Differentiation ◽  
Giant Cell ◽  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Sexual Development ◽  
Giant Cells ◽  
Second Phase ◽  
Developmental Phase ◽  
Calcium Dependent

Sexual development in Dictyostelium discoideum has many unique features making it an attractive eukaryotic model system for the study of biomembrane fusion and intercellular communication. The work presented here provides primary biochemical evidence for two distinct phases during early sexual development that appear to be defined by calcium-dependent gamete cell fusion. In addition, we introduce a novel procedure for the enrichment of zygote giant cells and use this method to define certain wheat-germ agglutinin binding glycoproteins which are specifically located in zygote giant cells and others which are markers for surrounding amoebae in the second phase of development. In addition, a G protein which is present in high amounts early in development is unique to giant cells in the second phase, suggesting a role in phagocytosis. Finally, alkaline phosphatase activity was found to mark the first phase of sexual development, suggesting a role in cell fusion. This contrasts with the patterns of α-mannosidase and β-glucosidase activity that increase late in the second developmental phase, where they likely function in endocyte digestion during the cytophagic period. The developmental significance of these findings is discussed.Key words: zygote giant cell differentiation, Ca2+, glycoproteins, GTP-binding proteins, alkaline phosphatase, glycosidase, cell fusion.

The immediate induction of extensive cell fusion by Ca2+ addition in Dictyostelium discoideum

1986 ◽  
Vol 64 (12) ◽  
pp. 1281-1287 ◽  
Author(s):  
David R. McConachie ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Cell Population ◽  
Giant Cells ◽  
Binucleate Cells ◽  
Large Numbers ◽  
Synchronous Cell ◽  
Extensive Cell ◽  
Chloride Salts

In mated cultures (NC4 × V12) of Dictyostelium discoideum containing 1.0 mM CaCl2, cell fusion generates large numbers of binucleate cells which develop into zygote giant cells. In the absence of Ca2+, binucleate formation does not occur. When 1.0 mM CaCl2 is added to Ca2+-deficient cultures at 18 h, 50% of the cells fuse within 45 min producing large multinucleate syncytia. Small, presumptive gametes appear in Ca2+-deficient cultures and reach a peak of about 20% of the cell population by 10 h, but they maintain this plateau and do not fuse. Upon the addition of CaCl2, the presumptive gametes immediately fuse, producing binucleate cells which develop rapidly into morphologically distinct giant cells. Cell fusion continues, resulting in the formation of extremely large (40–80 μm diameter) multinucleate syncytia by 45 min. The induction of this extensive, synchronous cell fusion does not occur in the presence of other chloride salts and EGTA inhibits it, revealing that Ca+ is the regulatory ion.

Nuclear fusion in multinucleated giant cells during the sexual development of Dictyostelium discoideum

1986 ◽  
Vol 118 (1) ◽  
pp. 95-102 ◽  
Author(s):  
H. Okada ◽  
Y. Hirota ◽  
R. Moriyama ◽  
Y. Saga ◽  
K. Yanagisawa
Keyword(s):  
Dictyostelium Discoideum ◽  
Sexual Development ◽  
Nuclear Fusion ◽  
Giant Cells ◽  
Multinucleated Giant Cells

Developmental effects of the major ions found in a groundwater sample on sexual cultures of Dictyostelium discoideum

1988 ◽  
Vol 34 (3) ◽  
pp. 207-211 ◽  
Author(s):  
Michael A. Lydan ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Major Ions ◽  
Giant Cells ◽  
Mixed Mating ◽  
Proteose Peptone ◽  
Liquid Culture Medium ◽  
Developmental Age ◽  
Combined Action ◽  
Sexual Cultures

Addition of 25 ppm magnesium, 40 ppm nitrate, 140 ppm sulphate, and 170 ppm chloride to mixed mating type cultures of Dictyostelium discoideum was found to both markedly increase the peak number and cause an earlier developmental age of appearance of binucleate and zygote giant cells over similar cultures made without the ions. Peak cell fusion values were enhanced by about 20% in ion-supplemented cultures. Developmental kinetics in separate cultures made with each component ion showed that the enhancement of cell type percentages and total cell fusion required the combined action of at least two of the ions. Lactose (0.1 %) – proteose peptone no. 3 (0.1%) liquid culture medium supplemented with the above ions yields a medium which maximizes cell fusion, facilitating its study during sexual development in D. discoideum.

scholarly journals A NEUROSPORA MUTATION THAT ARRESTS PERITHECIAL DEVELOPMENT AS EITHER MALE OR FEMALE PARENT

Genetics ◽  
1979 ◽  
Vol 92 (4) ◽  
pp. 1107-1120
Author(s):  
Thomas E Johnson
Keyword(s):  
Gene Product ◽  
Mating Type ◽  
Sexual Development ◽  
Female Parent ◽  
Male Parent ◽  
Mixed Mating ◽  
Single Mutation ◽  
Mating Types ◽  
Female Component ◽  
Ascospore Formation

ABSTRACT A mutant of Neurospora crassa fails to produce perithecia when crossed as either the male (fertilizing) parent or the female (protoperithecial) parent. This mutant is unique in that it appears to be due to a single mutation that blocks sexual development when crossed as either parent. As either a male or female parent, the mutant, fmf-1, produces perithecia blocked at a diameter of 120 microns and containing no meiotic figures; normal perithecia are over 4.00 microns in diameter. The mutant maps to linkage group IL near arg-1. Forced heterokaryons have been made between fmf-1 and fmf-1  + nuclei. These heterokaryons are fertile when crossed, and fmf-1 can participate as either the male or female component; the mutation is thus heterokaryon recessive and nuclear nonautonomous. Homokaryotic fmf-1 conidia were purified from a mixed conidial population derived from such a heterokaryon; these conidia failed to function as the male parent, suggesting that the fmf-1  + gene product is not contained in the conidium. In mixed mating-type heterokaryons, formed using tol, fmf-1 participates in ascospore formation and triggers perithecial development. Moreover, to1 suppreses the action of fmf-1 if present in both components of a cross.——These data suggest that (1) fmf-1 acts in the perithecium at some time between fusion of the conidium with the trichogyne and the onset of meiosis; (2) the fmf-1 gene product is not contained in conidia; and (3) both mating types may enter the protoperithecium when a mixed mating-type heterokaryon is used as the male parent.

Macrocyst development in Dictyostelium discoideum. II. Mating-type-specific cell fusion and acquisition of fusion-competence

1983 ◽  
Vol 60 (1) ◽  
pp. 157-168
Author(s):  
Y. Saga ◽  
H. Okada ◽  
K. Yanagisawa
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Mating Type ◽  
Cell Formation ◽  
Giant Cells ◽  
Specific Cell ◽  
Restrictive Temperature ◽  
Opposite Mating Type ◽  
Multinucleated Cells ◽  
Giant Cell Formation

The early events of macrocyst development in Dictyostelium discoideum have been investigated using a new culturing system. When cells of opposite mating-types, HM1 and NC4, are cultured together at the appropriate temperature in the dark, giant cells appear, ingest the surrounding amoebae, and develop into macrocysts. Although these giant cells have been assumed to be the products of the fusion of opposite mating-type cells, no experimental evidence to prove this assumption has been obtained using such mixed-culture systems. In order to avoid the complexities involved in mixed-culturing, we have developed a new system involving the separate culture, and later mixing, of opposite mating-type cells. This has enabled us to obtain direct evidence that giant cells are produced by fusion between opposite mating-type cells. Cell fusion occurs immediately after mixing and is completed within 30 min. As a number of cells fuse simultaneously, giant cells produced by this method are very large multinucleated cells, and not binucleated zygotes. Using this system we also discovered the following facts related to giant cell formation: (1) cells can acquire their fusion competence without the presence of cells of the opposite mating-type; (2) only HM1 cells require darkness to acquire their fusion competence; (3) the restrictive temperature, 25 degrees C, inhibits the induction of fusion competence in HM1 cells, but not in NC4 cells.

Aggregation during sexual development in Dictyostelium discoideum

1979 ◽  
Vol 25 (12) ◽  
pp. 1416-1426 ◽  
Author(s):  
Danton H. O'Day
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Sexual Development ◽  
Cell Aggregation ◽  
Giant Cells ◽  
Aggregation Process ◽  
Sequence Of Events

A microcinematographic analysis of the behaviour and movements of cells and cell masses in mated cultures (NC4 × V12) of Dictyostelium discoideum indicates that a chemotactic process directs cell aggregation during macrocyst development. Zygote giant cells form before aggregation begins and act as the aggregation centres. Young multicellular macrocyst stages are sources of cyclic AMP, and amoebae from macrocyst cultures orient chemotactically to cyclic AMP. The data, coupled with other characteristics such as pulsatile streaming, suggest that the aggregation process leading to macrocyst development is the same as that occurring during fruit construction. Other aspects of sexual development are also discussed. Based upon these data, we propose a model for the sequence of events leading to macrocyst development in D. discoideum.

The regulation of sexual development in Dictyostelium discoideum: cannibalistic behaviour of the giant cell

1985 ◽  
Vol 31 (5) ◽  
pp. 423-428 ◽  
Author(s):  
Keith E. Lewis ◽  
Danton H. O'Day
Keyword(s):  
Giant Cell ◽  
Dictyostelium Discoideum ◽  
Sexual Development ◽  
Giant Cells ◽  
Neutral Red ◽  
Cannibalistic Behaviour ◽  
Sexual Cultures ◽  
Drug Studies ◽  
Temperature Optima ◽  
Aerobic And Anaerobic

Sexual development leading to macrocyst formation in Dictyostelium discoideum involves the development of zygote giant cells which subsequently chemoattract and cannibalize local unfused amoebae of the same genotypes from which they formed. A system for assessing this process was developed wherein purified giant cells were fed amoebae under various conditions with the production of endocytes being assessed after neutral red staining of living cells. The phagocytic rate was linear during the 3-h assay period, was directly related to the concentration of amoebae, and demonstrated limited pH and temperature optima. Light which inhibits macrocyst development had no effect on sexual endocytosis. Cell-free conditioned medium from sexual cultures actively involved in phagocytosis enhanced giant cell endocytosis in the assay system. Drug studies revealed that microfilaments and microtubules are involved in the endocytic process and energy for it is supplied by both aerobic and anaerobic metabolic pathways. The data are discussed in terms of phagocytosis in D. discoideum and other organisms.

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