Arthropod ribosomes. Integrity of ribosomal ribonucleic acids from aphids and water fleas.

The 28 S aphid rRNA differs from those of the other insects in two points: (1) it lacks the primary nick; (2) it is larger by 0.2 - 106 daltons. The 28 S rRNA from water fleas also, like that from crayfish, is larger than those from comon insects by 0.2 - 106 daltons. These crustacean 28-S rRNAs were shown to contain the primary nick, which is probably not located in the central point. The 18-S rRNAs from aphids and water fleas had molecular weights significantly larger than 0.7 - 106, the common vaalue for the eukaryotic 18 S rRNA. It was was suggested that the 3'-terminal base sequences of these RNAs are different from the common sequences of these RNAs are different from the common sequence proposed for the 18 S rRNAA of eukaryotes. These exceptional characteristics of the rRNAs from the parthenogenetic animals may provide a probe for general functions of the rRNA in the eukaryotic ribosomes.