Virus-like particles associated with marine mussel mortalities in New Zealand

Green-lip mussel Pema canaliculus spat (15 to 30 mm length) in the outer Marlborough Sounds, New Zealand, suffered 50 to 100% mortality during January to April 1994 (summer/autumn) following thinning and reseeding of the mussel lines by farmers. Adult mussel mortalities of 2 to 5 % continued from February to early May 1994. Histological examination showed extensive haemocytosis and multifocal liquefaction necrosis of interstitial cells, basal cells and digestive tubule epithelial cells. Sloughed pyknotic or karyolytic digestive tubule epithelial cells formed characteristic rounded granular bodies 10 to 15 μm diameter both in digestive tubules and free in lesions . No viral inclusion bodies were observed. Ultrastructural examination showed highly modified rough endoplasmic reticulum associated with small, 25 to 45 nm diameter, electron- dense uncoated virus-like particles Identical cell damage and virus-like particles were subsequently found in monbund adult (75 to 110 mm length) P canaliculus and stunted (25 to 4 7 mm length) subt1dal Mvtilus galloprovincialis from the same area. Following purfication of extracts of the moribund spat by isopycnic centrifugation in CsCJ, large numbers of 25 nm diameter, unenveloped, virus particles were seen by electron microscopy. These particles had a density of 1.364 g cm- 3 A broad band at a density expected for enveloped particles (1.21to1.24 g cm 1 ) was also observed but contained few virus-like particles. Cell damage and mussel mortalities are thus likely due to a small unenveloped virus

Pines

Pinus is the most important genus within the Family Pinaceae and also within the gymnosperms by the number of species (109 species recognized by Farjon 2001) and by its contribution to forest ecosystems. All pine species are evergreen trees or shrubs. They are widely distributed in the northern hemisphere, from tropical areas to northern areas in America and Eurasia. Their natural range reaches the equator only in Southeast Asia. In Africa, natural occurrences are confined to the Mediterranean basin. Pines grow at various elevations from sea level (not usual in tropical areas) to highlands. Two main regions of diversity are recorded, the most important one in Central America (43 species found in Mexico) and a secondary one in China. Some species have a very wide natural range (e.g., P. ponderosa, P. sylvestris). Pines are adapted to a wide range of ecological conditions: from tropical (e.g., P. merkusii, P. kesiya, P. tropicalis), temperate (e.g., P. pungens, P. thunbergii), and subalpine (e.g., P. albicaulis, P. cembra) to boreal (e.g., P. pumila) climates (Richardson and Rundel 1998, Burdon 2002). They can grow in quite pure stands or in mixed forest with other conifers or broadleaved trees. Some species are especially adapted to forest fires, e.g., P. banksiana, in which fire is virtually essential for cone opening and seed dispersal. They can grow in arid conditions, on alluvial plain soils, on sandy soils, on rocky soils, or on marsh soils. Trees of some species can have a very long life as in P. longaeva (more than 3,000 years)