4.4 Ribosomal response between heat-tolerant and heat-sensitiveBrachionus species
Ribosome biogenesis is a complex and energy-demanding process requiring coordination of ribosomal RNA (rRNA) and ribosomal protein production. Ribosomal proteins have been mentioned several times to participate in stress response and they have been either induced or suppressed upon temperature increase (Lim et al., 2016; Podrabsky & Somero, 2004; Schoville et al., 2012; Truebano et al., 2010). Ribosomal protein related genes, in heat tolerant B. calyciflorus s.s., were up-regulated towards the lower imposed temperature here at 20oC, indicating again that 20 oC likely comprise stressful conditions for this species. In contrast, in the heat-sensitive B. fernandoi , ribosomal protein related genes were up-regulated under mild heat stress (23 oC), suggesting an increased translation capacity or a protection of ribosomal function through the addition or replacement of ribosomal proteins (Meistertzheim, Tanguy, Moraga, & Thébault, 2007). However, further temperature increase up to 26 oC, resulted in down-regulation of ribosomal related genes. This suppression of protein biosynthesis may reflect cellular homeostasis or an energy saving mechanism to cope with thermal stress, as protein metabolism consumes a large amount of ATP.