Mise en évidence, par électrophorèse, de trois fractions protéiniques fuchsinophiles dans la pars intercerebralis de Locusta migratoria

Abstract

Electrophoresis on polyacrylamide gel of extracts of pars intercerebralis of Locusta migratoria migratorioides which have been previously deprived of their neural lamella shows sixteen protein bands in larvae of the last two instars as well as in sexually mature adults. The proteinograms of the nervous tissues of the protocerebron surrounding the pars intercerebralis show thirteen protein bands which are homologous to the bands of the electrophoregrams of the pars intercerebralis. Electrophoretic analysis of less concentrated extracts demonstrates the heterogeneity of the larger bands 1, 5 and 8 which can be fractionated into two or three sub-bands. The differences in the proteinograms of the pars intercerebralis of larvae and adults are quantitative but not qualitative: in both the fractions are the same, display the same electrophoretic motility, but are more concentrated in the adults than in the larvae. Bands 13, 14 and 15, which show a strong anodic migration, are truly specific of the pars intercerebralis. They do not exist in the proteinograms of the other protocerebral tissues and do not appear in the electrophoretic patterns of proteins after the destruction of all the neurosecretory cells of the pars intercerebralis by electrocoagulation. These three bands of the pars intercerebralis are coloured by paraldehyde fuchsin as is the neurosecretory material of the A and C neurosecretory cells of the pars intercerebralis. The two fuchsinophile fractions 14 and 15 appear to be produced by the neurosecretory AB cells which occupy the centre of the pars intercerebralis. The selective electrocoagulation of the region containing the neurosecretory AB cells induces the disappearance of the two fuchsinophile bands 14 and 15. Fraction 13 is apparently linked to the neurosecretory C cells of the pars intercerebralis. Electrocoagulation of the neurosecretory C centre inhibits the appearance of fraction 13 in the electrophoretic patterns of proteins. The possibility of a relation between the fuchsinophile bands 13, 14 and 15 and the different neurocrine factors which are produced by the neurosecretory cells of the pars intercerebralis are discussed.