High impact information on ecmA

• Cells expressing the ecmA gene first appear as scattered cells at the mound stage of development and we show that this is also true for cells expressing the ecmB gene [1].
• Polysphondylium pallidum cells were transformed with a construct containing the Dictyostelium discoideum ecmA promoter fused to a lacZ reporter gene [2].
• Using B-galactosidase fusion constructs, which give more sensitive detection of gene expression, we now find that these cells express the ecmA gene but at a much lower level than pstA cells [3].
• Expression of the mutant G alpha 2 from the SP60 prespore promoter or wild-type G alpha 2 from either the ecmA or the SP60 promoter results in no detectable phenotype [4].
• When this promoter region is coupled to lacZ, beta-gal expression is restricted to the multicellular stages and localized in prestalk cells with a pattern similar to that of the ecmA prestalk-specific promoter [4].

Biological context of ecmA

• We find that under all conditions of low cell density in which express ion the ecmA fusion gene occurs, it is invariably detected in less than 25% of the cells from a clonal population [5].
• To help resolve these differences, we have used transformed cells containing the promoter of the prestalk gene ecmA fused to beta-galactosidase (Jermyn and Williams, 1991) to study the differentiation of Dictyostelium cells at low cell density, at which cell-to-cell interactions and morphogen gradients are minimal [5].

Anatomical context of ecmA

• The ecmA (pDd63) and ecmB (pDd56) genes encode extracellular matrix proteins of the slime sheath and stalk tube of Dictyostelium discoideum [3].
• 8-Br-cAMP, which is believed to penetrate the cell membrane and activate protein kinase A, induced ecmB, but not ecmA, in the absence of the conditioned medium [6].

Other interactions of ecmA

• We previously identified a third class of prestalk cells, pstO cells, which lie behind pstA cells in the slug anterior and which appeared to express neither the ecmA nor the ecmB gene [3].

Analytical, diagnostic and therapeutic context of ecmA

• We then used double-labeled immunofluorescence to examine the ontogeny of the CP2-positive and the ecmA-positive cells [5].

References