Fig. 2.

A, Northern analysis of argK mRNA in different stages of grasshopper embryogenesis detects a single transcript of ∼2.4 kb. There is a gradual increase in the amount of transcript in 30, 40, and 50% stage embryos. In 70% stage embryos, argK is transcribed at a high level, probably because of muscle maturation. In each lane, 20 μg of total RNA was loaded. The blot was probed with ³²P-labeled grasshopper argK cDNA. RNA size standards are in kilobases. B, Immunoblotting withLimulus anti-argK polyclonal antibody shows grasshopper argK is ∼40 KDa, and there is only one form (the faster migrating band in 100% embryo is likely a degradation product). Equal amounts of total protein were loaded in each lane. There is an increase of argK expression from 32 to 55% and 100% stage total embryo. Within 55% stage embryos, with the same amount of total protein loaded, there is more argK in the CNS than in the limb. In the adult, more argK is detected in the muscle than in CNS ganglia. Protein size standards are in kilodaltons. C, Enzymatic activity of grasshopper argK is present in different tissues and in different stages of development. Equal amounts of total protein were loaded in each lane. Grasshopper argK migrated to the same distance as that ofAedes (mosquito) but faster thanDrosophila argK. Within grasshopper, an abrupt increase in enzyme activity was observed after the 55% stage, concomitant with the maturation of muscle.