PMC

Venn diagrams give the overlap of C. elegans genes upregulated (A) and downregulated (B) at least 2-fold (P<0.01) in response to C. albicans and heat-killed C. albicans, each compared to heat-killed E. coli. See for gene identities.

The C. albicans efg1Δ/efg1Δ cph1Δ/cph1Δ double mutant strain (efg1/cph1) exhibited a reduced ability to kill C. elegans compared to its isogenic wild-type parent strain SC5314 (P<0.001). The graph presents the average of three plates per strain, each with 30 to 40 animals per plate. Data are representative of two biological replicates.

A Venn diagram illustrates the overlap of genes induced 2-fold or greater (P<0.01) by C. albicans (this study), P. aeruginosa and S. aureus . All microarrays were conducted using the Affymetrix platform. Animals were exposed to C. albicans and P. aeruginosa for 4 hours and to S. aureus for 8 hours. See for gene identities.

The induction of abf-2, fipr-22/23, cnc-4 and cnc-7 is reduced in wild-type C. elegans animals during infection with the virulence-attenuated C. albicans efg1Δ/efg1Δ cph1Δ/cph1Δ double mutant strain [vs. heat-killed (HK) E. coli] compared to its isogenic wild-type parent strain SC5314 (vs. heat-killed E. coli). Data are presented as the average of three biological replicates, each conducted in duplicate and normalized to a control gene with error bars representing SEM. *P = 0.06, **P<0.01 and ***P<0.025 for the comparison of gene induction on SC5314 versus efg1Δ/efg1Δ cph1Δ/cph1Δ.

(A) A Venn diagram illustrates that a subset of C. albicans downregulated genes were upregulated after infection of C. elegans by pathogenic bacteria. See for gene identities. (B) Transgenic C. elegans animals in which GFP expression was driven by the promoter for the C-type lectin clec-60, a secreted S. aureus immune effector that was downregulated by C. albicans in the microarray analysis, are shown. Worms were exposed to heat-killed (HK) E. coli, heat-killed C. albicans or live C. albicans for 20 hours at 25°C and then imaged. Green is clec-60::GFP. Red is the myo-2::mCherry co-injection marker used to identify transgenic animals.

(A) Live C. albicans (closed diamonds) were pathogenic to nematodes on solid media, whereas heat-killed C. albicans (open circles) and E. coli (crosses) were not (P<0.001). The graph presents the average of three plates per strain, each with 30 to 40 animals per plate. Data are representative of two biological replicates. (B) Images of C. elegans animals exposed to heat-killed E. coli (HK E.c.), heat-killed C. albicans (HK C.a.) or live C. albicans (live C.a.) for 16 hours at 25°C are shown. Images of the proximal (left) and distal (right) intestine were obtained using Nomarski optics. Both live and heat-killed C. albicans accumulated within the intestine, but only live C. albicans caused marked distention of the proximal intestine. Arrows point to the pharyngeal grinder and arrowheads outline the lumen of the intestine. The scale bar represents 20 µm.

(A) A C. albicans infection assay with wild-type (N2) and pmk-1(km25) animals shows that pmk-1(km25) mutants were more susceptible to C. albicans infection (P<0.01). Each time point represents the average of three plates per strain, each with 30 to 40 animals per plate. Data are representative of two independent experiments. (B) N2 and pmk-1(km25) young adult animals were exposed to the indicated food source and the indicated genes were studied using qRT-PCR (HK equals heat-killed). Expression is relative to N2 on heat-killed E. coli and the data are presented as the average of three biological replicates each normalized to a control gene with error bars representing SEM. *P<0.001 and **P equals 0.05 for the comparison of relative expression of the indicated gene in wild-type animals on C. albicans versus pmk-1(km25) animals on C. albicans.

(A) C. elegans genes that were differentially regulated in C. albicans-exposed versus heat-killed E. coli-exposed young adult animals at 4 hours after infection are depicted on a genome-wide intensity plot of 22,548 sequences. Genes colored red were upregulated by C. albicans (P<0.01), those colored green were downregulated (P<0.01) and those colored blue were unchanged. Diagonal lines represent 2-fold change and the numbers of genes differentially regulated greater than 2-fold are indicated (P<0.01)(124 genes were upregulated and 189 genes were downregulated). (B) qRT-PCR was used to confirm the results of the microarray analysis. 11 genes with varying degrees of differential regulation were selected and studied under each condition in which they were differentially regulated in the microarray analysis (see for gene identities). Correlation of microarray and qRT-PCR data was determined by plotting the average fold difference observed in the microarray analysis (three biological replicates) versus the average fold difference for the same gene obtained by qRT-PCR (three biological replicates). Linear regression analysis revealed strong correlation between the datasets (R² of 0.90).