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A key event in Dictyostelium development is the formation of the Mexican hat. This corresponds to a commitment step in morphogenesis that irreversibly signals progression from the slug stage to the fruiting body. We describe the characterization of the dhkK gene that controls this morphogenetic step. Null mutants of dhkK repeatedly attempt, and fail, to undergo morphogenesis from the slug to the Mexican hat, causing them to exhibit a "slugger" phenotype, which cannot be corrected by co-development with wild-type cells. The dhkK gene encodes a putative receptor histidine kinase whose expression is enriched in prestalk cells in the slug. Uniquely for a histidine kinase, DhkK is located in the nuclear envelope. Entry into culmination requires the DhkK response regulator domain, which appears to directly regulate cyclic AMP signaling. 相似文献
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John Sternfeld 《Development genes and evolution》1998,208(9):487-494
Shortly after initiation of Dictyostelium fruiting body formation, prespore cells begin to differentiate into non-motile spores. Although these cells lose their ability
to move, they are, nevertheless, elevated to the tip of the stalk. Removal of the amoeboid anterior-like cells, located above
the differentiating spores in the developing fruiting body, prevents further spore elevation although the stalk continues
to elongate. Furthermore, replacement of the anterior-like cells with anterior-like cells from another fruiting body largely
restores the ability to lift the spores to the top of the stalk. However, if amoeboid prestalk cells are used to replace the
anterior-like cells, there is no restoration of spore elevation. Finally, when a droplet of mineral oil replaces differentiating
spores, it is treated as are the spores: the mineral oil is elevated in the presence of anterior-like cells and becomes arrested
on the stalk in the absence of anterior-like cells. Because a similar droplet of mineral oil is totally ignored by slug tissue,
it appears that there is a dramatic transformation in the treatment of non-motile matter at this point in Dictyostelium development.
Received: 26 January 1998 / Accepted: 27 May 1998 相似文献
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