Fig 1.
Percentage of total N. ceranae transcripts detected over the infection period.
Over 28% of N. ceranae transcripts were detected to express as early as 1 dpi. The expressed transcripts increased dramatically from 42.5% at 2 dpi to 91.5% at 3 dpi, followed by a steady increase to 96.4% at 6 dpi. The largest increase in the expressed transcripts was between 2 dpi and 3 dpi, which might reflect an increase in meront reproduction and sporonts formation.
Fig 2.
N. ceranae gene expression pattern during the infection period.
There were 1122 genes significantly differentially expressed during the infection period, clustering into 4 expression patterns based on the expression levels as above. The X axis represents post-infection day and the Y axis represents average counts of clustered genes.
Fig 3.
SNP positions within 1479 shared genes in N. ceranae parasites collected in 2007 and 2013.
A: The average number of SNP decreased from 9.1 per gene to 4.36 per gene (p < 0.001). B: Within the total SNP count, the average number of synonymous substitutions decreased from 4.5 in 2007 to 2.81 in 2013. C: The average non-synonomous SNP level dropped from 4.58 in 2007 to 1.85 in 2013. X axis represents two sample groups. Y axis represents number of SNP positions.
Fig 4.
Six-way Venn diagram showing the distribution of shared significantly regulated host transcripts during the infection period, relative to control honey bees of the same age.
Numbers of clusters are provided in the interactions. The total number of significantly regulated host transcripts is provided for each day post infection.
Table 1.
Immunity related genes and involved pathways.
Fig 5.
(A) Count ratios derived from mRNA sequencing for parasitic PIWI and Dicer. Y = Log((CPIWI/CDICER), 2), where CPIWI represents normalized counts of parasitic gene PIWI and CDICER represents normalized counts of parasitic gene DICER. The expression of Dicer was only detected starting at 2 dpi, hence data for 1 dpi is missing. (B) Real time quantitative PCR originated expression value of the ratio between parasitic PIWI and Dicer. Y = Log((CtDICER/CtPIWI), 2), where CtDICER represents the Ct value of gene DICER and CtPIWI represents the Ct value of gene PIWI. The expression level of PIWI is consistently higher than Dicer with the same expression pattern as sequencing data, which confirmed the validity of the sequencing data. (C) mRNA sequencing originated counts of immune gene Apidaecin, which shows significant change over the infection time with a similar expression pattern of qPCR results showed in (D). (E) The mRNA sequencing data of Hymenoptaecin again showed significant change over the infection time and shared the same expression pattern as the qPCR results in (F). The consistent expression pattern between the sequencing data and the qPCR results validated the accuracy of the sequencing data. Error bar represents standard error. * represents the significant level at 0.05. ** represents the significant level at 0.01.