Fig. 4. Symmorphosis at the RNA level. Transcript–structure correlations bring about significant functional relationships. These concern the coordination of gene expression between the nuclear and mitochondrial genomes and the match of lipase expression to rate and capacity of fatty acid metabolism. (A) Correlation of mitochondrial-encoded COX1 and nuclear-encoded COX4 mRNA levels with mitochondrial volume density per fiber, i.e. Vv(mt,f). (B) Micrograph showing an intramyocellular droplet of lipid (IMCL) being enveloped by a mitochondrion. The pathway involved in the oxidative combustion of IMCL-derived fatty acids (FA) in mitochondria is indicated by a green arrow. The suspected localization of HSL and the correlation coefficients (r) between HSL mRNA with volume density of intramuscular lipids, Vv(li,f), and volume density of mitochondria, Vv(mt,f), are given in black and white font, respectively.