The 'prespore-like cells' of Dictyostelium have ceased to express a prespore gene: analysis using short-lived beta-galactosidases as reporters.
In transgenic strains of Dictyostelium discoideum that express beta-galactosidase under the control of a prespore-specific promoter, only early slugs show reporter confined to the prespore zone. As slugs migrate beta-galactosidase-positive cells accumulate in the prestalk zone; ultimately, there may be so many that the prestalk-prespore boundary is no longer distinguishable (Harwood, A., Early, A., Jermyn, K. and Williams, J. (1991) Differentiation 46, 7-13). It is not clear whether these 'anomalous' reporter-positive cells currently express prespore genes; another possibility is that they are ex-prespore cells that have transformed to prestalk and sorted to the prestalk zone (Sternfeld, J. (1993) Roux Archiv. Dev. Biol. 201, 354-363), while retaining their previously produced reporter. To test the activity of the prespore genes in these cells, we have made prespore reporter constructs whose products decay quickly; these are based on constructs used to investigate protein turnover in yeast (Bachmair, A., Finley, D. and Varshavsky, A. (1986) Science 234, 179-186). In strains bearing such constructs, beta-galactosidase-positive cells do not appear in the prestalk zone. The apparent deterioration of the prestalk/prespore pattern in older slugs is thus an artefact of reporter stability.
Detterbeck
S
S
Zoologisches Institut, Ludwig-Maximilians-Universität, München, Germany.
Morandini
P
P
Wetterauer
B
B
Bachmair
A
A
Fischer
K
K
MacWilliams
H K
HK
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000235:genetics; D017931:DNA Primers; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D013170:Spores; D001616:beta-Galactosidase / Q000235:genetics*
D017931:DNA Primers; D001616:beta-Galactosidase