TAXONOMY Potato spindle tuber viroid (PSTVd) is the type species of the genus Posipiviroid, family Pospiviroidae. An absence of hammerhead ribozymes and the presence of a 'central conserved region' distinguish PSTVd and related viroids from members of a second viroid family, the Avsunviroidae. PHYSICAL PROPERTIES Viroids are small, unencapsidated, circular, single-stranded RNA molecules which...

Rhizoctonia sheath diseases of rice, comprising sheath blight, sheath spot and aggregate sheath spot, cause significant yield losses in many rice-growing regions of the world. The emergence of Rhizoctonia sheath diseases as economically important rice diseases is of recent date and has been attributed to the intensification of rice-cropping systems with the development of new short-stature, hig...

Many chemicals with broad industrial, pharmaceutical and agricultural application produce a neurotoxic syndrome in humans and experimental animals involving weight loss, skeletal muscle weakness and ataxia. Neurotoxicity is defined as a structural change or a functional alteration of the nervous system resulting from exposure to a chemical, biological or physical agent. Neurotoxicity including ...