Figure 1.
Temporal changes of mean water temperature (A), salinity (B) and gonad development (C) across an annual cycle in mussel Mytilus galloprovincialis (Lam.) from Bizerta lagoon (Tunisia).
Note that sampling periods were as follows: March-December 2007; January–April 2008.
Figure 2.
Mytilus galloprovincialis gene expression profiles of digestive gland tissue across the annual cycle.
The heat map (A) (Pearson correlation, complete linkage algorithm) and the expression view plot (B) report the log2 relative expression level with respect to the selected reference condition (January). 295 differentially expressed genes were generated in at least one condition. Microarray data were analyzed using the Linear Mode for Microarray Analysis (LIMMA) software as described in [50]. B statistics with adjusted p value <0.05 and B>0 were used as threshold for rejection of the null hypothesis (no variation). Supporting information to Figure 2 is present on Dataset S1.
Figure 3.
Decomposition of gene expression profile.
The k-means algorithm was used for the computation of different gene expression trends in the set of 295 unique genes whose expression was modulated in female digestive gland across the annual cycle (Fig 2 and Dataset S1). K-means is an iterative procedure aimed to reduce the variance to a minimum within each cluster [55], [56]. A tendency curve (centroid) is also depicted (pink solid line). In further analysis, genes included in clusters 1 and 4 were considered together as the two groups differed only for the intensity of relative mRNA abundance. Supporting information to Figure 3 is present on Dataset S2.
Table 1.
GO term over-representation analysis of k-means clustered genes.
Table 2.
GO term over-representation analysis of sex specific genes in the digestive tissue across the four stage of gonadal development.
Figure 4.
mRNA abundance patterns across female gonad maturation in mantles.
Shown are representative images of the reproductive stage of female gonad (1: Early stage-November 2007, 2: Development -January 2008, 3: Ripe -February 2008, and 4: Spawning -March 2008) determined according to [46], the heat map (B) (Pearson correlation, complete linkage algorithm) and the expression view plot (C) obtained for each stage vs the reference condition (stage I). 369 differentially expressed genes in at least one condition were considered for the analysis. Supporting information to Figure 4 is present in Dataset S4.
Figure 5.
mRNA abundance patterns across male gonad maturation in mantles.
Shown are representative images of the reproductive stage of male gonad (1: Early stage-November 2007, 2: Development -January 2008, 3: Ripe -February 2008, and 4: Spawning -March 2008) determined according to [46], the heat map (B) (Pearson correlation, complete linkage algorithm) and the transcription view plot (C) representing the log2 relative expression obtained for each stage vs reference condition (stage I). 354 differentially expressed genes in at least one condition were considered for the analysis. Supporting information to Figure 5 is present on Dataset S5.