The coat protein of potato virus X is a strain-specific elicitor of Rx1-mediated virus resistance in potato.

The Rx1 gene in potato confers extreme resistance to potato virus X (PVX). To investigate the mechanism and elicitation of Rx resistance, protoplasts of potato cv. Cara (Rx1 genotype) and Maris Bard (rx1 genotype) were inoculated with PVX and tobacco mosaic virus (TMV). At 24 h post-inoculation in Maris Bard protoplasts there was at least 100-fold more PVX RNA than in protoplasts of Cara. TMV RNA accumulated to the same level in both types of protoplast. However, when the TMV was inoculated together with PVX the accumulation of TMV RNA was suppressed in the Cara (Rx1 genotype) protoplasts to the same extent as PVX. The Rx1 resistance also suppressed accumulation of a recombinant TMV in which the coat protein gene was replaced with the coat protein gene of PVX. It is therefore concluded that Rx1-mediated resistance is elicited by the PVX coat protein, independently of any other proteins encoded by PVX. The domain of the coat protein with elicitor activity was localized by deletion and mutation analysis to the structural core of a nonvirion form of the coat protein.

Genital papillomatosis in sperm whale bulls.

Examination of 31 male sperm whales (Physeter catodon) caught off the western coast of Iceland revealed three cases of genital papillomatosis involving the unsheathed penis. One subadult and two sexually mature bulls were affected. Gross lesions resembled papillomas common in terrestrial mammalian species. Transmission electron microscopy of these lesions revealed nonenveloped intranuclear virus particles 28-40 nm in diameter and round to hexagonal in shape. In two cases immunoperoxidase staining was negative for group-specific papillomavirus antigen. These findings indicate that the spectrum of animal species affected with virus-associated genital papillomatosis includes at least one globally distributed species of the order Cetacea (whales, dolpins, and porpoises).

Unusual multisystemic pathology in a sperm whale bull.

This report describes an unusual combination of lesions and apparent behavioral abnormalities in a sexually mature sperm whale bull taken in whaling operations off Iceland. Lesions included heavy combative scarring of the head, grossly roughened and thickened skin on the lower left flank, cutaneous maculae, genital papillomatosis, partial duodenal obstruction by plastic debris, colo-rectal obstruction by ambergris, cystic degeneration of the right kidney, and a deeply ulcerative gastric nematodiasis. Sealskin was found in the stomach. Gross and histopathologic observations suggested that the disease complex in this animal may have been related both to habitat degradation and health risks naturally associated with its ecology and age.

Syntheses and pharmacological activity of substituted imidazolidinethiones and thiomidazolines.

A series of imidazolidinethiones and thioimidazolines was synthesized and tested for their effects on both forced and spontaneous motor activity as well as for their ability to raise the convulsion threshold. The proton NMR spectra for the thioimidazolines synthesized were unusual in that they showed a sharp singlet for the ring ethylene unit rather than the expected A2B2 pattern. The thioimidazolines, 5 and 7, were the most active CNS depressants and had the highest safety index. Significantly, the isomeric imidazolidinethiones, 8 and 9, were comparatively much less effective while being considerably more toxic.

The differential diagnosis of cataracts in infancy and childhood.

The differential diagnosis of cataracts in childhood encompasses a broad and fascinating range of diseases and syndromes. Etiologic factors are catalogued according to type and character of the cataracts of infancy and childhood.