Cytochemical characterization of Triatoma infestans and Panstrongylus megistus salivary gland cells (Hemiptera, Reduviidae, Triatominae) A.C.B. Anhe ˆ, M.T.V. Azeredo-Oliveira * Departamento de Biologia, Instituto de Biocieˆncias, Letras e Cieˆncias Exatas – Universidade Estadual Paulista ‘‘Ju ´lio de Mesquita Filho’’ – IBILCE/UNESP, Sa˜o Jose ´ do Rio Preto, SP, Brazil 1. Introduction Triatomines (Hemiptera, Reduviidae) are hematophagous insects of medical importance as they act as invertebrate hosts of Trypanosoma cruzi, which causes Chagas Disease. This infirmity occurs in Latin America and infects about 9–12 million people (Souza, 2007). Triatomines, especially Rhodnius genus, are also hosts of T. rangeli, which is apparently harmless to humans but can be pathogenic to the insect vector (Hecker et al., 1990). Both species share common antigens and cross-react serologically, which hinders differential diagnosis of parasitemias (Cuba Cuba, 1998). Triatomines of Triatoma and Panstrongylus genera have a salivary complex formed by a pair of glands, each pair containing three independent units: D1 (anterior or main), D2 (median or supplementary) and D3 (posterior or accessory) (Barth, 1954). The first is elongated and whitish, the second is rounded and yellowish and the third is rounded and translucent (Reis et al., 2003). Salivary gland cells have two nuclei with accentuated poly- ploidy (Barth, 1954). Recently, acid phosphatase technique showed enzyme activity in the heterochromatin and nucleolus, which showed the most intense response (Anhe ˆ et al., 2007). Ultra- structural analysis showed abundant endoplasmic reticulum, mitochondria and microvilli in the apical plasma membrane domain, thus enlarging the membrane area available for saliva secretion (Reis et al., 2003; Meirelles et al., 2003). However, cytochemical characteristics of these polyploid cells are less known. Saliva of these hematophagous insects abounds in substances that facilitate feeding, like anticoagulants (Hellmann and Hawkins, 1964, 1965; Pereira et al., 1996; Ribeiro et al., 1998), antihista- mines (Ribeiro and Walker, 1994), vasodilators (Ribeiro et al., 1990, 1993; Ribeiro and Nussenzveig, 1993) and inhibitors of platelet aggregation (Ribeiro and Garcia, 1980,1981; Sarkis et al., 1986; Micron 39 (2008) 1126–1133 ARTICLE INFO Article history: Received 20 December 2007 Received in revised form 18 June 2008 Accepted 19 June 2008 Keywords: Chromatin Nucleolar corpuscles Polyploidy nuclei Salivary glands Triatominae Hemiptera ABSTRACT The Triatominae subfamily has medical sanitary importance, since these insects are vectors of Trypanosoma cruzi, etiologic agent of Chagas Disease, and Trypanosoma rangeli, which develops in the salivary glands and it is frequently found in mixed infections with T. cruzi. Triatomines of Triatoma and Panstrongylus genera possess a salivary gland complex composed of a pair with three well differentiated units: the anterior (D1), median (D2) and posterior (D3). Saliva is secreted during blood meal and antagonizes hemostatic, inflammatory and immunological systems imposed by the host, which facilitate the hematophagy. In order to identify nuclear structures, we studied interphase nuclei of salivary gland cells of adult insects, males and females, of Triatoma infestans and Panstrongylus megistus. The glands were removed from insects, fixed in acetic acid (45%) and lactic acid (50%), squashed and submitted to different cytochemical methods: lacto-acetic orcein, silver ion impregnation, Feulgen reaction, Toluidine Blue, Variant method of critical electrolyte concentration and C-banding. The preparations were examined with a Zeiss Jenaval photomicroscope and photographed. The results evidenced predominance of binucleated cells in D1 and D2 glands and mononucleated ones in D3. In all salivary glands were observed bulky and polyploid nucleus, a clear association between nucleolar and heterochromatic corpuscles, cytoplasmatic metachromasy and many pre-secretion vesicles in cytoplasm. Such characteristics were associated with intense synthesis activity to produce the saliva. Species were mainly differentiated by a larger heterochromatic corpuscle observed only in T. infestans (called as chromocenter), while P. megistus showed a predominance of euchromatin, with some heterochromatic corpuscles just in males. Females of both species showed a smaller quantity of heterochromatin, which could be related to the high metabolism because of the oviposition. ß 2008 Elsevier Ltd. All rights reserved. * Corresponding author. E-mail address: tercilia@ibilce.unesp.br (M.T.V. Azeredo-Oliveira). Contents lists available at ScienceDirect Micron journal homepage: www.elsevier.com/locate/micron 0968-4328/$ – see front matter ß 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.micron.2008.06.003