QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Varney, T. R. Articles by Blumberg, D. D. Search for Related Content PubMed PubMed Citation Articles by Varney, T. R. Articles by Blumberg, D. D. Social Bookmarking                         What's this?

A novel disintegrin domain protein affects early cell type specification and pattern formation in Dictyostelium

Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA

View larger version (65K): [in a new window]   Fig. 1. During ampA– strain development, expression of the pspD reporter gene is induced prematurely and prespore reporter activity is observed in cells in regions normally occupied by prestalk cells. PspD reporter expression patterns are shown for wild-type (left) and ampA– structures (right) for the following developmental stages: (A,B) tight mounds (10 hours development), 4 hours staining; (C,D), tips (13.5 hours development), 2.5 hours staining; (E,F), early culminants (18 hours development), 2.5 hours staining. Arrows indicate regions of the structures where prestalk cells are usually found. (G) Quantitation of the number of cells expressing the pspD reporter in wild-type and ampA null structures harvested at 14 hours of development. Developing structures were dispersed to single cells, fixed, stained and counted as described in the Materials and Methods.

View larger version (84K): [in a new window]   Fig. 2. Mis-expression of pspD reporter is rescued by the presence of wild-type cells in chimeric structures. Patterns of pspD reporter expression in wild-type, ampA– and chimeric structures formed by 2 day bacteria-fed cells are shown. Samples were prepared as described in Materials and Methods. All samples shown were stained for ß-galactosidase activity for 2 to 3 hours. (A) 100% wild-type cells, reporter in all cells; 18 hours of development. (B) 100% ampA– cells, reporter in all cells; 18 hours of development (C) 50% wild-type cells/50% ampA– cells, reporter in all cells; 14 hours of development to show mound stage. Arrows in B,C indicate the position of prestalk cells at the mound periphery at this stage. These cells are stained in B, but unstained in C. (D) 50% wild-type cells/50% ampA– cells, reporter in all cells; 18 hours of development. (E) 50% wild-type cells/50% ampA– cells, reporter in ampA– cells only; 18 hours of development. (F), 10% wild-type cells/90% ampA– cells, reporter in all cells; 18 hours of development. Black arrows in A,D,E,F indicate the tips that are composed of prestalk cells and devoid of prespore cells. Gray arrows in E indicate clustering of ampA null cells carrying the pspD reporter clustering at the base of the prespore zone.

View larger version (109K): [in a new window]   Fig. 3. Loss of AmpA function delays differentiation of prestalk cells and migration of stalk A cells from the mound periphery to the mound tip. EcmA reporter expression patterns are shown for wild-type structures (left) and ampA– structures (right) for the following developmental stages: (A,B), tight mounds, 10 hours of development; 2 hours staining. (C,D), late tight mounds, 12 hours of development; 1 hour staining. (E,F), tips, 13.5 hours of development; 1 hour staining. (G,H) Culminants, 22 hours of development, 1 hour staining. Arrows indicate the mound periphery where stalk A cells initially differentiate.

View larger version (120K): [in a new window]   Fig. 4. The delay in prestalk gene expression and anterior prestalk cell migration in structures formed from ampA-null cells is rescued by the presence of wild-type cells. (A-C) Expression patterns of ecmA reporter after 14 hours of development by bacterially grown cells are shown. (A) Wild type; (B) ampA–; (C) 50/50 wild type/null with reporter carried only in ampA-null cells. (D-F) 18 hours of development by bacterially grown cells is shown. (D) Wild type; (E) ampA-null; (F) 10/90 wild type/null chimera with reporter carried in null cells only. (G) 50:50 wild-type/ampA– cells, reporter in all cells; 18 hours development. (H) 50:50 wild-type/ampA– cells, reporter in ampA– cells only; 18 hours development. All staining was for 1 to 2 hours.

View larger version (31K): [in a new window]   Fig. 5. Inactivation of ampA gene function results in a premature increase in the percentage of cells expressing the ampA reporter at the earliest developmental stages. Axenically growing wild-type (A) and ampA– (B) cells carrying the ampA reporter gene were washed free of growth medium, plated for development on nitrocellulose filters and stained 19 hours for expression of ß-galactosidase after 4 hours of development as described in the Materials and Methods. (C) Quantification of the percentage of cells expressing the ampA reporter in developing wild-type and ampA– structures during development on nitrocellulose filters. Structures harvested at 12 hours of development were dispersed to single cells, and fixed, stained and counted as described in the Materials and Methods.

View larger version (74K): [in a new window]   Fig. 6. Inactivation of ampA gene function results in a decrease in the number of cells expressing the ampA reporter in the region of the upper cup during late development. ampA reporter gene expression patterns for wild-type (A,C) and ampA– (B,D) structures formed by axenically grown cells are shown. (A,B) Early culminants (18 hours development); 29 hours staining. (C,D) Culminants (24 hours development); 20 hours staining. Arrows indicate the regions of the upper cup where reporter expression is reduced in ampA– aggregates relative to wild type. (E-H) Wild-type and ampA– cells were grown in the presence of bacteria. Suspensions of wild-type cells, ampA– cells or wild-type/ampA– cell mixtures were plated for 18 hours of development. Samples were fixed and stained 22 to 24 hours for ß-galactosidase activity. (E) 100% wild-type cells, reporter in all cells; (F) 100% ampA– cells, reporter in all cells; (G) 50% wild-type cells/50% ampA– cells, reporter in all cells; (H) 50% wild-type cells/50% ampA– cells, reporter in ampA– cells only. Arrows indicate regions of the structures where upper cup cells should be found.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter