32:	Advances in genetics in Acetabularia: controlled crosses, selections & germplasm storage.

Authors:	Higgins, Christopher, C-P.(A)Hunt, Brenda, E.(A)Mandoli, Dina, F.(A)
Affiliations:	(A): University of Washington (B): Eden Biosciences
Presenter:	Mandoli, Dina F., mandoli@u.washington.edu

Genetics, a powerful tool for the study of all facets of biology, has been underused in the classic developmental model system, Acetabularia acetabulum. This giant, unicellular green alga has a single diploid nucleus for most of its life cycle yet produces 2-6 million progeny per cell per generation. The species has just two mating types, "-" and "+", which are probably allelic because they segregate at meiosis. Each plant makes both mating types. Conveniently, each mating type is packaged in separate spherical gametangia so controlled self- and out-crosses simply entail putting two gametangia in proximity. We will present our most recent solutions to the remaining stumbling blocks that hinder genetic studies in this species: synchronous induction of gamete release, longterm storage of germplasm and facile selection of transformants. 10 mM potassium is optimal for gametangial viability during storage of germplasm and for gamete release. The effects of light quality, nutrient availability and protease treatment on gamete release will also be discussed. Cold, dark conditions in a specific, artificial seawater enable the storage of germplasm for over 2 years. The effect of sugar-coating germplasm prior to storage (as has been done for seeds) will also be presented. Finally, FACS of zygotes will enable studies of zygote differentiation and may allow us to select putative transformants expressing GFP targeted to the nucleus. These advances should increase the attractiveness of this organism as a model system. Supported by REU award (CH) to grant NSF #96-30618 (DFM).