A Ca2+-dependent early functional heterogeneity in amoebae of Dictyostelium discoideum, revealed by flow cytometry

Azhar, M and Manogaran, PS and Kennady, PK and Pande, G and Nanjundiah, Vidyanand (1996) A Ca2+-dependent early functional heterogeneity in amoebae of Dictyostelium discoideum, revealed by flow cytometry. In: Experimental Cell Research., 227 (02). pp. 344-351.

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Abstract

When freshly starved amoebae of Dictyostelium discoideum are loaded with the Ca2+-specific dye indo-1/AM and analyzed in a fluorescence-activated cell sorter, they exhibit a quasi-bimodal distribution of fluorescence. This permits a separation of the population into two classes: H, or ''high Ca2+-indo-1 fluorescence,'' and L, or ''low Ca2+-indo-1 fluorescence.'' Simultaneous monitoring of Ca2+-indo-1 and Ca2+-chlortetracycline fluorescence shows that by and large the same cells tend to have high (or low) levels of both cytoplasmic and sequestered Ca2+. Next we label H cells with tetramethylrhodamine isothiocyanate (TRITC) and mix them in a 1:4 ratio with L cells, In the slugs that result, TRITC fluorescence is confined mainly to the anterior prestalk region. This implies that amoebae with relatively high Ca2+ at the vegetative stage tend to develop into prestalk cells and those with low Ca2+ into prespores. Polysphondylium violaceum, a cellular slime mold that does not possess prestalk and prespore cells, also does not display a Ca2+-dependent heterogeneity at the vegetative stage or in slugs. Finally, confirming earlier findings with the fluorophore fura-2 (Azhar ef al., Curr. Sci. 68, 337-342 (1995)), a prestalk-prespore difference in cellular Ca2+ is present in the cells of the slug in vivo. These findings are discussed in light of the possible roles of Ca2+ for cell differentiation in D. discoideum.

Item Type:	Journal Article
Publication:	Experimental Cell Research.
Publisher:	Academic Press
Additional Information:	Copyright of this article belongs to Academic Press.
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	11 Mar 2009 05:12
Last Modified:	19 Sep 2010 05:28
URI:	http://eprints.iisc.ac.in/id/eprint/19442

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