Salivary proteins of aphids, a pilot study on identification, separation and immunolocalisation

Salivary proteins (SPs) of Schizaphis graminum, Acyrthosiphon pisum and Myz us persicae were studied after probing and feeding on different artificial diets. Salivary sheaths as well as apical lumps of saliva were found, presu mably representing subsequently excreted saliva of different types. Phenolo xidase, pectinase and peroxidase activities were detected by staining the e nzyme-converted products, thus confirming these enzyme activities found ear lier by others. Proteinase and cellulase were not found. SPs in three major SDS-PAGE bands, at 154 and 66/69 kDa, were collected in fluid diets (solub le fraction) and as sheath material (solid fraction) attached to the membra nes covering these diets. Proteins of both fractions presumably represented the enzymatic activities found, although this could not be proven. The lac k of electrophoretic mobility of the undenaturated (isoelectrofocusing and PAGE) active proteins meant that they could not be separated, whereas the m obile denaturated (SDS-PAGE) proteins had lost their enzyme activity. Polyc lonal antibodies, anti-SP154 and anti-SP66/69, both cross-reacted to most s alivary proteins in Western blots. They also reacted to sheath material and to the principal salivary glands. For further studies of saliva some monoc lonal antibodies were developed. The complexity of salivation and the relat ion of the results obtained to the behaviourally known secretion periods is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.