Figure 1.
Mortality induced by N. ceranae.
Data show the percentages of surviving bees per replicate (n = 3) and per day in cages composed of 30 bees each (90 bees total/treatment). Cages with N. ceranae infected bees achieved one-hundred percent of mortality at day 14 post infection, while in control groups mortality remained low.
Table 1.
Functional analysis of honey bee genes affected N. ceranae parasitism.
Figure 2.
Activity of antioxidant enzymes in the midguts of bees challenged by N. ceranae.
Differences in enzymatic activity of A) superoxide dismutase (SOD), B) glutathione reductase (GR), C) glutathione peroxydase (GP) and D) glutathione-S-transferase (GST) were estimated by a Mann-Whitney U test. Means±SE are shown for 4 pools of 3 midguts per replicate (n = 3 replicates, 36 bees total/treatment). * and ** denote significant differences at p<0.05 and p<0.01, respectively.
Figure 3.
Histology of honey bee midguts 7 days post-infection.
Light microscopy analysis of control (A, B) and N. ceranae infected midguts (C, D) stained with Hematoxylin-Eosin. In control guts, the peritrophic membrane (pm) and epithelial cells (ec) are homogenous, while in parasitized the guts peritrophic membrane and epithelial cells show signs of degeneration and lyses, respectively. Similar lesions were observed in each infected bees (n = 2 bees per replicate and treatment, giving n = 6 bees per treatment). A) and C) x100, B) and D) x400. Scale bar: 10 µm.
Figure 4.
Network of genes downregulated by Nosema in the bee gut.
The composite functional association network derived from different genomic and proteomic data sources was generated with GeneMania using the Drosophila orthologs of bee genes. Physical and genetic interactions between genes are indicated by dot and solid lines, respectively. Grey and white circles represent implemented genes (known genes affected by Nosema) and new genes predicted to be functionally associated to the known genes, respectively. The size of the predicted gene circle provides an indication of its interaction score. Except ETS-domain lacking (edl), the predicted genes roundabout (robo), longitudinal (lola), Cyclin D (CycD), Optix, kekkon-1 (kek1) had bee orthologs: GB17658, GB12094, GB14028, GB16761 and GB17490.
Figure 5.
Activity of alkaline phosphatase (AP) in the midguts of bees challenged by N. ceranae.
Means±SE are shown for 4 pools of 3 midguts per replicate (n = 3 replicates, 36 bees total/treatment). ** denotes significant differences at p<0.01 using a Mann-Whitney U test.