title: Attraction between sexes: male-female gametocyte behaviour within a Leucocytozoon toddi (Haemosporida).
abstract: Understanding the breeding systems of Plasmodium, and the closely related Haemoproteus and Leucocytozoon (Apicomplexa: Haemosporida), is fundamental to virulence and transmission research. We report an unusual binding behaviour between gametocytes of Leucocytozoon toddi. This aggregative behaviour was notably characterised by a disparity in the likelihood of clustering by female and male gametocytes. Thus, indicating a possible difference in the 'stickiness' of gametocytes per sex. Overall, 12% of gametocytes in this high-parasitaemia infection (0.269 gametocytes per 100 red blood cells (RBCs)) were incorporated into aggregations involving substantial contact. The gametocyte sexual combinations within aggregations varied significantly from expected according to the background 0.49 sex ratio within this sample, with female-female contacts occurring more and male-male contacts occurring less frequently than expected. A second L. toddi (identical for 709 bp of the cyt b mitochondrial gene) with lower parasitemia (0.035 gametocytes per 100 RBCs) showed no significant binding. Interestingly, the ratios of male gametocytes in both of these parasites were greater than expected under sex-ratio theory and similar to the 50% observed in species with syzygy breeding strategies. We discuss the ramifications of this observation in terms of sex-ratio theory and breeding strategies and provide speculative explanations for this unusual gametocyte behaviour.
authors.affiliation: Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, BP 1274, Antananarivo 101, Madagascar. r.k.barraclough@massey.ac.nz
authors.forename: Rosemary K
authors.initials: RK
authors.lastname: Barraclough
authors.forename: Linda
authors.initials: L
authors.lastname: Duval
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Talman
authors.forename: Frédéric
authors.initials: F
authors.lastname: Ariey
authors.forename: Vincent
authors.initials: V
authors.lastname: Robert
mesh_terms: D000818:Animals; D001717:Birds / Q000469:parasitology; D002449:Cell Aggregation / Q000502:physiology*; D045303:Cytochromes b / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D005260:Female; D005854:Germ Cells / Q000166:cytology / Q000502:physiology*; D016787:Haemosporida / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D045303:Cytochromes b