Cell Biology International 1999, Vol. 23, No. 3, 219–226 Article No. cbir.1998.0337, available online at http://www.idealibrary.com on PARTIAL CHARACTERIZATION OF MOSQUITO LARVAE EXTRACT MODULATING MOUSE AND HUMAN CELL PROLIFERATION J. R. RONDEROS 1 *, O. J. RIMOLDI 2 , M. A. SALAS 3 and R. R. BRENNER 2 1 Ca ´tedra de Histologı ´a y Embriologı ´a ‘B’, Facultad de Ciencias Me ´dicas—Universidad Nacional de la Plata, Calle 60 y 120, 1900 La Plata, Argentina 2 INIBIOLP, UNLP-CONICET; and 3 Ca ´tedra de Fisiologı ´a con Biofı ´sica, FCM-UNLP, Argentina Received 20 April 1998, accepted 9 December 1998 Mosquito larvae crude extract have been found to alter the mitotic rate of several mouse epithelial cell populations such as enterocytes and tongue keratinocytes. Also, the dialysed fraction inhibits hepatocyte proliferation in hepatectomized males. These experiments suggested an inhibitory effect on the G1/S interphase. Consequently, we suggested the presence of some molecule or molecules related to the TGF- superfamily. In the present paper, we have assayed the crude extract on human mononuclear cells and the dialysed fraction of the extract on tongue keratinocyte proliferation. Furthermore, different protein fractions obtained using a molecular exclusion chromatographic column were assayed on hepatocyte proliferation of hepatectomized mice. Three groups of proteins have been isolated. Results show a dose- dependent effect of crude extract on mononuclear cell proliferation and the dialysed extract caused an inhibitory effect on tongue keratinocyte proliferation. With regard to the hepatocyte mitotic rate, an inhibitory effect appeared only in animals receiving the fraction with lower molecular weight. These results suggest the presence in mosquito larvae of some peptidic molecule or molecules resembling the activity of members of the TGF- superfamily.  1999 Academic Press K: keratinocytes; hepatocytes; mononuclear cells; mosquito; growth factors. INTRODUCTION Cell populations have different cycle times which can vary according to distinct life times. Moreover, there exist cycling and noncycling cells in every population, depending on the require- ments of the organism. Cell growth is regulated by several factors such as hormones, growth factors and cell surface receptor synthesis. As growth caused by cell proliferation is a fundamental process in biology, some genes involved in it have probably appeared in the genome by the time of mitosis appearance. Several factors control- ling growth mechanisms such as growth factors and proto-oncogenes, have been maintained in nature throughout evolution. Thus, such distant organisms as insects and mammals share some of these genes. Genes codifying proteins structurally related to transforming growth factor-beta (TGF-) and epidermal growth factor (EGF) have been found in insects, nematodes and echinoderms (Padgett et al., 1987; Massague, 1990; Muskavitch and Hoffmann, 1990; Doctor et al., 1992; Ren et al., 1996). The presence of a gene in Drosophila that encodes a receptor of the TGF- superfamily was also evidenced (Tin Xie et al., 1994). Further- more, the decapentaplegic gene, which codifies a protein highly homologous with TGF-, was reported as an imaginal disk cell synchroniser at the G2/M interphase during Drosophila eye development (Penton et al., 1997). In view of these facts, it could be expected that the mechanism controlling cell growth were not species specific. *To whom correspondence should be addressed. E-mail: jrondero@museo.fcnym.unlp.edu.ar The biological material used in the in vivo experiments performed in this paper was collected from Ca ´tedera de Histologı ´a y Embriologı ´a ‘A’, Facultad de Ciencias Me ´dicas, Universidad Nacional de La Plata, where Dr J. R. Ronderos developed his activities until July 1996. 1065–6995/99/030219+08 $30.00/0  1999 Academic Press