Changing Patterns of Gene Expression in Dictyostelium Prestalk Cell Subtypes Recognized by In Situ Hybridization with Genes from Microarray Analyses

Abstract

We used microarrays carrying most of the genes that are developmentally regulated in Dictyostelium to discover those that are preferentially expressed in prestalk cells. Prestalk cells are localized at the front of slugs and play crucial roles in morphogenesis and slug migration. Using whole-mount in situ hybridization, we were able to verify 104 prestalk genes. Three of these were found to be expressed only in cells at the very front of slugs, the PstA cell type. Another 10 genes were found to be expressed in the small number of cells that form a central core at the anterior, the PstAB cell type. The rest of the prestalk-specific genes are expressed in PstO cells, which are found immediately posterior to PstA cells but anterior to 80% of the slug that consists of prespore cells. Half of these are also expressed in PstA cells. At later stages of development, the patterns of expression of a considerable number of these prestalk genes changes significantly, allowing us to further subdivide them. Some are expressed at much higher levels during culmination, while others are repressed. These results demonstrate the extremely dynamic nature of cell-type-specific expression in Dictyostelium and further define the changing physiology of the cell types. One of the signals that affect gene expression in PstO cells is the hexaphenone DIF-1. We found that expression of about half of the PstO-specific genes were affected in a mutant that is unable to synthesize DIF-1, while the rest appeared to be DIF independent. These results indicate that differentiation of some aspects of PstO cells can occur in the absence of DIF-1.

Identification of new modes of Dd-STATa regulation of gene expression in Dictyostelium by in situ hybridisation

“…Among the 104 ESTs previously analysed by in situ hybridisation, we chose 37 pstA or pstAO, 8 pstAB and 8 late prestalk genes whose expression patterns are very clear (Maeda et al, 2003). Expression patterns of all these genes were analyzed and compared between wild-type (Ax2) and DdSTATa-null strains (Tables I, II).…”

“…Whole-mount in situ hybridisation analyses were performed as described previously (Escalante and Loomis, 1995;Maeda et al, 2000;2003). In this study, Ax2 and Dd-STATa-null cells in an Ax2 background were allowed to develop on filter paper (FILTER PA-PER 4A, ADVANTEC, Tokyo, Japan) placed on nonnutrient agar at 22ºC.…”

Analysis of the Leishmania donovani transcriptome reveals an ordered progression of transient and permanent changes in gene expression during differentiation

“…In other organisms, DNA microarray analysis has become a popular and powerful method for examining changes in gene expression during differentiation and/or adaptation to new growth conditions [52][53][54][55][56][57]. While this approach has been used previously to compare the different lifecycle stages (procyclics, metacyclics and amastigotes) of L. major [39][40][41], L. donovani [42], L. infantum [43], and L. mexicana [44], the work presented in this paper represents the first genome-wide analysis of changes in gene expression during the transition from promastigotes to amastigotes, a process which was impossible to follow until host-free differentiation systems had been developed.…”

The cell adhesion molecule DdCAD-1 regulates morphogenesis through differential spatiotemporal expression inDictyostelium discoideum

“…During Dictyostelium development, cells that are starved in different cell cycle phases tend to reach the aggregate at different times and therefore occupy different positions within the aggregate. Cells in the periphery, which are usually starved at S phase or early G2 phase, differentiate mostly into prestalk cells, suggesting that a combination of cell cycle stage and positional information dictates cell fate (Gomer and Firtel, 1987;Maeda et al, 2003;Weijer, 2009;Weijer et al, 1984;Zimmermann and Weijer, 1993). Although both wild-type and cadA -cells are capable of differentiating into the different cell types required for fruiting body formation, the cadA -cells achieve 100% cheating and form spores exclusively in chimeras.…”