Archives of Insect Biochemistry and Physiology 43:9–15 (2000) © 2000 Wiley-Liss, Inc. Salivary Gland Proteins of the Mosquito Culex quinquefasciatus Eva Pereira Nascimento, Rosely dos Santos Malafronte, and Osvaldo Marinotti* Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Brazil Several properties of the salivary glands of Culex quinque- fasciatus mosquitoes were analysed. The amount of protein in female salivary glands increased from 0.26 mg on day one after emergence to about 1.4 mg on day seven. The major polypep- tides found in the female salivary glands had molecular weights of 35.7, 28.3, and 20.5 kDa. Antibodies produced by mice immu- nized by bites of Culex quinquefasciatus female mosquitoes re- acted with the 35.7 and 28.3 kDa polypeptides, showing that these molecules were secreted by mosquitoes during blood feed- ing. The salivary glands of C. quinquefasciatus females dis- played the same morphological and biochemical organization as that of Aedes aegypti mosquitoes, accumulating apyrase in the distal portions and a-glucosidase in the proximal portions of the gland. Arch. Insect Biochem. Physiol. 43:9–15, 2000. © 2000 Wiley-Liss, Inc. Key words:culex; salivary glands; saliva; mosquito Contract grant sponsor: Conselho Nacional de Desenvol- vimento Científico e Tecnologico (CNPq); Contract grant sponsor: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP). *Correspondence to: Dr. Osvaldo Marinotti, Universidade de São Paulo-ICB, Dept. Parasitologia, Avenida Professor Lineu Prestes 1374, CEP 05508-900, São Paulo, SP, Brazil. E-mail: omarinot@icb.usp.br Received 29 March 1999; accepted 9 August 1999 INTRODUCTION Much work has focused on the study of mos- quito salivary glands. These organs are the final destination of several pathogens before they are transmitted to vertebrate hosts. Among these pathogens are the malaria parasites transmitted by anopheline mosquitoes and arboviruses such as dengue, yellow fever, and encephalitis that are transmitted by culicine mosquitoes. The saliva produced by the mosquito salivary glands is the vehicle that carries these pathogens and also it may enhance or facilitate infectivity as previously reported (Ribeiro, 1995; Osorio et al., 1996; Edwards et al., 1998). Although research on mos- quito salivary glands has focused on their role in pathogen transmission, their role in food ingestion and digestion has also been examined (James, 1994). The saliva of mosquitoes contains a-glucosi- dases and a-amylases that initiate the digestion of carbohydrates present in dietary sugar sources and other enzymes and peptides involved in blood finding and ingestion such as anticoagulants, va- sodilators, and platelet aggregation inhibitors (Stark and James, 1996a). Furthermore, the mos- quito saliva contains immunogens that elicit al- lergic reactions in the vertebrate hosts (Peng et al., 1995; Peng and Simons, 1997). The proteins present in the salivary glands of several mosquito species have been investigated (Al-Ahdal et al., 1990; Mellink and vanZeben, 1976; Poehling, 1979; Racioppi and Spielman,