Objective In mosses, almost any vegetative cell from either the gametophyte or sporophyte can regenerate to form protonema, which subsequently gives rise to leafy shoots (gametophores). In some species, plants characteristically regenerated from sporophyte tissue (aposporous regenerants) produce sporophytic structures directly, bypassing gamete and zygote formation (apogamy). In the moss P. intermedia, n = 52 this process proceeds especially actively. Comparison of the extent of formation of apogamous structures in moss plants isolated from different sites, but cultured under identical conditions, will give information on the genetic basis of apogamy in the diplophase of the moss. The main aim of the project, however, concerns the epigenetic control of apogamy in the diplophase; this control in mosses being tightly related to the alternation of generations. The zygote within the archegonium is determined to develop into the sporophyte. An observation, central to study of cell fate determination, is that the apogamy in P. intermedia has been shown to persist very strongly during vegetative propagation of aposporous plants, the capacity for apogamy being transmit by individual aposporous protonemal cells, including those regenerated from isolated protoplasts. The capacity for apogamy is lost however in the process of meiospore formation.Apogamy has also been found to be absent frequently in aposporous regenerants from the tissue of spore sac walls and sometimes in regenerants derived from tissues non-adjacent to sporogenous tissue.New data on the nature of the inheritance of the determined state will be obtained by:(a) employing protoplast fusion to produce somatic hybrids between haploid protonemal cells and between cells from aposporous clones, either able and unable to transmit the capacity to produce apogamous structures;(b) using chemical and physical treatments which have been proposed to influence epigenetic cellular memory, to assess their effect on the expression of apogamy.To investigate further the role of chromosome doubling and zygote formation in the origin and maintenance of the determined state, morphology, functional state of nuclear DNA and esterase isozymes activity will be compared (a) in P. intermedia diploids obtained from isolated protoplasts fusion, verifying whether DNA supercoiling of one fusion partner artificially mimics zygote formation (b) in apogamous and non-apogamous clones from plants of identical genotype.The differential role of nucleus and cytoplasm in the origin and maintenance of the determined state, crucial for determining a possible role for a proposed cytoplasmic determinant of apogamy, will be studied by analysing morphological and functional characters of somatic hybrids made between differently-determined cells, where one fusion partner has nuclei that have been experimentally inhibited. To test current hypotheses of epigenetic cellular memory, as well as proposals connecting a cellular memory with the participation of some facultative mobile genomic component or to a self-maintaining arrangement of the cytoskeleton and membrane components, the effects on apogamy expression of following agents will be investigated: inhibitors of DNA transcription, of RNA translation, modifiers of gene expression, inhibitors of DNA methylation, DNA intercalating agents, analogues of arginine and lysine, different chemical and physical stresses, microtubule- and microfilament-disrupting agents.For elucidating the role of meiosis in the elimination of the capacity for apogamy, the effect of experimentally induced somatic reduction will be tested. The project results will provide information on the mechanism of cellular memory and the inheritance of determined state in moss development, and provide information more generally applicable to the study of this phenomenon central to organism development. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Topic(s) 4 - Life Sciences OPEN - OPEN Call Call for proposal Data not available Funding Scheme Data not available Coordinator University of Leeds EU contribution No data Address Woodhouse Lane LS2 9JT Leeds United Kingdom See on map Total cost No data Participants (3) Sort alphabetically Sort by EU Contribution Expand all Collapse all Freie Universität Berlin Germany EU contribution No data Address Koenigin Luise Strasse 12 - 16 14195 Berlin See on map Total cost No data National Academy of Sciences of Ukraine Ukraine EU contribution No data Address 14/16 Drahomanov Street 79005 Lviv See on map Total cost No data National Academy of Sciences of Ukraine Ukraine EU contribution No data Address 11 Stephanyk Street 79000 Lviv See on map Total cost No data
