A positive fold change indicates the gene was expressed to a greater extent within a condition. An asterisk (*) indicates that the gene
was significantly differentially expressed (p <0.05, t-test) and the error bars on the RT-qPCR data represent the standard deviation between the biological replicates GDC-0449 manufacturer of mycelia, spherules at day 2 and spherules at day 8. A recent paper by Whiston et al. assessed transcription in C. immitis and C. posadasii mycelia and day 4 spherules by RNA-seq [13]. We have compared our results to theirs. The two studies used different methods for assessing changes in gene expression. We used microarray technology to estimate transcript abundance VX-689 nmr while Whiston et al. used RNA-seq to estimate transcript abundance [13]. The literature suggests that these methods should yield comparable results [24]. Despite this difference in methodology, we confirmed the upregulation of 25% of the genes that Whiston found to be upregulated in spherules. Conversely, 43% of genes that we have found to be upregulated in day 2 and day 8 spherules were also upregulated in day 4 spherules in the Whiston study (Additional file 5: Figure S2). Despite the differences in the two studies many of our conclusions are similar (see
below). We know from previous experiments that some genes are overexpressed in spherules compared to mycelia. Some of these genes, such as the spherule outer wall glycoprotein (CIMG_04613) [25] and the parasitic-phase specific protein PSP-1 (CIMG_05758) [26] were up regulated more than four fold in spherules in this experiment (Additional file 4: Table S2). nearly Other
genes, such as the metalloproteinase Mep1 (CIMG_06703), which has been found to be expressed at high levels in endosporulating spherules in C. posadasii was not found to be over-expressed in this experiment [27]. We also examined the expression level of the Mep1 gene by RT-qPCR and found that its expression was slightly downregulated in spherules compared to mycelia, rather than upregulated as previously reported (see below). Whiston et al. also examined the expression of this gene and found that it was upregulated in C. posadasii spherules but not C. immitis spherules [13]. Confirmation of differential expression by RT-qPCR Twenty-four differentially expressed genes as detected by microarray analysis were learn more selected for confirmation by RT-qPCR (Figure 3). Genes were selected for RT-qPCR confirmation of gene expression based on the magnitude of fold change (up- or downregulation) between mycelia and day 2 spherules, mycelia and day 8 spherules, and day 2 and day 8 spherules, and their identification in the PFAM or GO analysis. The significant differential expression (p < 0.05, t-test) of each of these 24 genes was confirmed for at least one of the three comparison groups.