Parasitology

Research Article

Vesicle trafficking during sporozoite development in Plasmodium berghei: ultrastructural evidence for a novel trafficking mechanism

J. SCHREVELa1, G. ASFAUX-FOUCHERa1, J. M. HOPKINSa2, V. ROBERTa1a3, C. BOURGOUINa4, G. PRENSIERa5 and L. H. BANNISTERa2 c1

a1 Muséum National d'Histoire Naturelle, USM 504 Biologie fonctionnelle des Protozoaires, EA 3335, CP 52, 61 Rue Buffon, 75231 Paris Cedex 05, France

a2 Department of Anatomy and Life Sciences, Wolfson CARD, Hodgkin Building, King's College London, Guy's Hospital Campus, London SE1 1UL, UK

a3 Institut de Recherche pour le Développement, UR 77 Paludologie afro-tropicale, 213 rue La Fayette, 75480 Paris cedex 10, France

a4 Institut Pasteur, Centre for Production and Infection of Anopheles CEPIA, 28 rue du Dr Roux, 75724 Paris cedex 15, France

a5 Laboratoire de Biologie Cellulaire et Microscopie Electronique, UFR Médecine, 10 Bd Tonnellé 37032 Tours cedex 1, France

SUMMARY

Oocysts from Anopheles stephensi mosquitoes fed on murine blood infected with Plasmodium berghei berghei, were fixed for electron microscopy 6–12 days post-feeding. Ultrastructural analysis focused on Golgi-related trafficking pathways for rhoptry and microneme formation during sporogony. A small Golgi complex of 1–3 cisternae is formed close to the spindle pole body from coated vesicles budded from the nuclear envelope which is confluent with the endoplasmic reticulum. Rhoptries begin as small spheroidal bodies apparently formed by fusion of Golgi-derived vesicles, lengthening to 3–4 μm, and increasing in number to 4 per sporozoite. Ultrastructural data indicate the presence of a novel mechanism for vesicle transport between the Golgi complex and rhoptries along a longitudinal 30 nm – thick fibre (rootlet fibre or tigelle). Filamentous links between vesicles and rootlet indicate that this is a previously undescribed vesicle transport organelle. Genesis of micronemes occurs late in bud maturation and starts as spheroidal dense-cored vesicles (pro-micronemes), transforming to their mature bottle-like shape as they move apically. Filamentous links also occur between micronemes and subpellicular microtubules, indicating that as in merozoites, micronemes are trafficked actively along these structures.

(Received May 12 2007)

(Revised July 16 2007)

(Accepted July 23 2007)

(Online publication October 02 2007)

Correspondence:

c1 Corresponding author: Department of Anatomy and Life Sciences, Wolfson CARD, Hodgkin Building, Guy's Campus, King's College London, London SE1 1UL. Tel: +44 (0) 20 8653 3042. Fax: +44 (0) 20 7848 6569. E-mail: Lawrencelban@aol.com

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