Table 1. Summary of nucleotide preferences shown by 90% of genes that are highly expressed in zebrafish and mouse.

	Zebrafish	Mouse
Optimal codon frequency	> 38.7%	> 36.9%
Minor codon frequency	< 12.3%	< 11.5%
Rare codon frequency	< 2.9%	< 2.9%
Initiator structure (kcal/mol)	> −13.1	> −12.9
Stop tetranucleotide	UAAa	UAAa
Kozak-like sequence	gccatc	gccacc
CG frequency	< 8.2%	< 8.5%
TA frequency	< 6.7%	< 6.7%

Initiator structure refers to free energy of the minimum energy structure for nucleotides −4 to +37 relative to the start codon and was calculated at 28°C for zebrafish and 37°C for mouse.