Studies on the secretion of the female reproductive accessory glands of Ceratitis capitata

The female reproductive system of Ceratitis capitata has a pair of accessory glands whose structure has been recently studied. Their epithelium consists of a flattened layer of cells, secretory cells and duct-forming cells, lined by a thin cuticle. Analysis of the secretion reveals the presence of proteins and polysaccharides with a range of 0.5 to 1 µg total protein per gland. SDS-PAGE electrophoresis of the secretion shows several major bands comprised between 13 and 38 kDa. Two-dimensional electrophoresis gives several isoelectric forms concentrated within two main groups: one focalizing between pH 4.5-5.5 and the other between pH 5-5-6.5. Monodimensional isoelectric focusing and anion exchange chromatography of native proteins reveal two classes of proteins distributed at acidic and neutral pH ranges, respectively. Alkaline phosphatases and N-acetyl–ß-D-galactosaminidases have been detected in the secretion. The results relative to the latter enzyme are in line with previous evidence that the micropyle cap of ovary eggs contains binding sites for Dolichos biflorus agglutinin, a lectin specific for galactosamine residues; these binding sites disappear in laid eggs, presumably because of enzymatic hydrolysis of the carbohydrate groups. This report contributes to the knowledge of the role of the accessory gland secretion in the reproduction of the medfly Ceratitis capitata.