Parasitology



Changes of mate occur in Schistosoma mansoni


L. PICA-MATTOCCIA a1, R. MORONI a1, L. A. TCHUEM TCHUENTÉ a2a3, V. R. SOUTHGATE a2 and D. CIOLI a1c1
a1 Institute of Cell Biology, National Research Council, 43 Viale Marx, 00137 Rome, Italy
a2 Biomedical Sciences Division, Department of Zoology, The Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
a3 General Biology Laboratory, Faculty of Sciences, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon

Abstract

Male and female schistosomes are generally assumed to form stable monogamous pairs for the whole span of their long existence in the mammalian host. Recent evidence from mixed infections has shown that Schistosoma mansoni males can displace S. intercalatum males from their homologous partners, but no information exists about the existence of similar phenomena within a single schistosome species. Here, we determine whether male S. mansoni can displace males of the same species from pre-formed pairs in vivo. The availability of clear-cut genetic markers of drug resistance in schistosomes was exploited to show that hycanthone sensitive S. mansoni males can displace homospecific hycanthone resistant males from pre-formed pairs and vice versa. The frequency of changes is dependent on the magnitude of the excess single males competing with paired worms. The possible mechanics and the biological significance of mate changing are discussed.

(Received June 24 1999)
(Revised November 12 1999)
(Accepted November 12 1999)


Key Words: Schistosoma mansoni; drug resistance; mating competition; change of partners.

Correspondence:
c1 Corresponding author: Institute of Cell Biology, 43 Viale Marx, 00137 Rome, Italy. Tel: +39 06 86090340. Fax: +39 06 827 3287. E-mail: dcioli@ibc.rm.cnr.it


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