Does electrophoresis of cockroach muscle proteins detect recognition molecules?

Abstract

IN some animals, particularly amphibia and insects, normal function is ultimately restored in a limb which has been denervated. In the cockroach it has been shown that identified motoneurones reinnervate the same leg muscles as they did before the nerve was sectioned^1,2. A possible explanation is that each muscle has specific molecules by which ingrowing nerves are able to recognise their appropriate destination. Recently, Denburg³, using sodium dodecyl sulphate(SDS)–polyacrylamide gel electrophoresis has shown that these cockroach muscles have distinct gel protein patterns which he suggests represent specific recognition molecules. Alternatively, the differences may arise because the motor neurones he considers are physiologically different types, ‘fast’ and ‘slow’. To test this interpretation we have examined a number of other cockroach muscles using Denburg's methods. All the muscles have patterns which may be grouped into the same categories as Denburg's even though they are innervated by different neurones. Where the innervation by ‘fast’ and ‘slow’ neurones is known the correspondence with our data is good. Furthermore, locust flight muscles with solely ‘fast’ innervation all have identical patterns. We conclude that gel electrophoresis patterns demonstrate a characteristic of the type of innervation rather than representing specific recognition molecules.