Mini cistrons are present in the mRNA leading regions of some baculoviral genes. By analyzing the codon usage of insect genes

the early

late and polyhedrin genes and mini cistrons of baculovirus

it is found that mini cistrons prefer minor codons to major codons that are rich in polyhedrin genes; have repeat codons whose content is 250 times very higher than in the polyhedrin genes;almost all mini cistrons are inframe with the succeeding major cistrons; and most ATG of mini cistrons are in good context for translation.All above suggest that the mini cistrons are a distinct kind of gene which has particular function. In this paper

it is proposed that the function of mini cistron may be similar to that of attenuator

namely attenuating or stutting off translation of the succeeding major cistron under the condition of low amino tRNA. \ \