Stratmann, Johannes and Paputsoglu, Georg and Oertel, Wolfgang (1996) Differentiation of Ulva mutabilis (Chlorophyta) gametangia and gamete release are controlled by extracellular inhibitors. JOURNAL OF PHYCOLOGY, 32 (6). pp. 1009-1021. ISSN 0022-3646, 1529-8817
Full text not available from this repository.Abstract
Blade cells of Ulva mutabilis Foyn (Chlorophyta) excrete regulatory factors into their cell walls and into the environment. These factors are essential for the maintenance of the vegetative state. ''Sporulation inhibitor-1a'' (SI-1a) is a glycoprotein that was isolated from the culture medium of axenic Ulva growing as an undifferentiated callus. This protein was unusually stable to denaturing treatments and showed an extremely high apparent molecular mass (M(r)) of 1-4 X 10(7) daltons estimated by size exclusion chromatography. The glycosylation was not essential for activity. SI-1a suppressed gametogenesis completely at concentrations lower than 10(-14) M. When Ulva developed normally in the presence of their symbiotic bacteria, smaller forms of SI-1 accumulated in the medium (10(4) - 10(6) daltons). Sporulation inhibitors of the same size spectrum and with similar properties were also extracted from crude cell walls of nonaxenic Ulva. A class of different nonprotein sporulation inhibitors (SI-2) of very low M(r) and yet unknown structure was isolated from the inner space between the two blade cell layers. Excretion of all SI-1 forms decreased with maturation of the thallus, whereas the overally concentration of SI-2 in the thallus stayed constant throughout the life cycle. The SI-2 affected different Ulva species whereas SI-1 was species-specific. Gametogenesis was induced upon removal of both sporulation inhibitors from small single-layered fragments of mature blades. After a ''determination phase'' of 23-46 h, dependent on the time of induction within the cell cycle, the cells became irreversibly committed to differentiation and were no longer susceptible to SI-1 or SI-2. Subsequently, during a 28-h ''differentiation phase,'' 16 progametes were formed by synchronous genome doublings and cell divisions and differentiated into mature gametes. These became motile and were released from the gametangia when the concentration of a ''swarming inhibitor'' of low M(r), excreted mainly during the ''determination phase,'' declined below a threshold concentration. The biochemical properties of these regulatory factors and their effects on gametogenesis and gamete release are described.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CHLOROPLAST GENOME; NUCLEAR; VOLVOX; DNA; cell differentiation; Chlorophyta; gamete release; plant development; regulation of gametogenesis; sporulation inhibitors; swarming inhibitor; Ulva mutabilis |
| Subjects: | 500 Science > 540 Chemistry & allied sciences 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 25 May 2023 11:26 |
| Last Modified: | 25 May 2023 11:26 |
| URI: | https://pred.uni-regensburg.de/id/eprint/51306 |
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