A Virus Infection in the Brown Alga Sorocarpus uvaeformis (Lyngbye) Pringsheim (Phaeophyta, Ectocarpales)

Virus-like particles were obsemed in zoospores and less frequentlyin vegetative cells of the filaments of mature plants of thebrown alga Sorocarpus uvaeformls. The particles, measuring approximately170 nm in diameter, are isometric in profile and show threedistinct zones. An electron dense rim (coat), 10 nm in thickness,is separated from a dense core, 110 nm in diameter, by an electronlight space 20 nm in width. When closely packed the particlesare usually separated from each other by a regular halo-likespace. Besides the isometric particles long flexuous structuresof variable length and measuring 75 nm in width were also found.The infection could be induced experimentally in healthy cellsby using either medium prevenient from infected cultures orcrude extracts obtained from infected plants.