Lectin Binding to Meloidogyne javanica Eggs.

T h e egg shell is one of the most impor tant and least understood of the nematode's protective membranes. The egg shell of Meloidogyne incognita consists mostly of proteins (50%), chitin (30%), and traces of lipids and unidentified materials (1). In the present work we used fluorescein isothiocyanate (FITC)-labeled lectins (2) to identify the carbohydrate residues on the gelatinous matr ix and the egg shells of the rootknot nematode, Meloidogyne ]'avanica. Egg masses and egg shells were dissected and separated from infected tomato roots as described by Bird and McClure (1). Th e fluorescein-labeled lect ins-Concanaval ine A (Con A), soybean agglutinin (SBA), and wheat germ agglutinin (WGA)--were reacted with the gelatinous matr ix and the egg shells by the labeling technique described for neural crest cells (3). The specificity of the observed lectin adsorption and the fluorescence microscopy observations were detected as described by Sieber-Blum and Cohen (3). Proteolytic digestion of phosphate-buffered saline (PBS, pH 7.4) washed nematodes and neuraminidase pretreatments were accomplished as described by us previously (4). Con A and WGA caused a strong fluorescence intensity all over the outer surface of M. javanica gelatinous matr ix (Fig. 1). SBA did not reveal any fluorescence in the gelatinous matrix, and pret reatment with neuraminidase or proteolytic enzymes did not change the results. Nevertheless, the presence of N-acetyl-galactosamine or galactose residues in the gelatinous matr ix of M. javanica is not completely ruled out by the lectin-binding studies, since these sugars may be inaccessible to the lectin. Egg shells of M. ]avanica were highly fluorescinated by FITC-labeled Con A, SBA, and WGA (Fig. 2). WGA binding provided