Clavibacter michiganensis subsp. Sepedonicus Elicits a Hypersensitive Response in Tobacco and Secretes Hypersensitive Response-Inducing Protein(s).

ABSTRACT Strains of Clavibacter michiganensis subsp. sepedonicus, causal agent of bacterial ring rot of potato, showed marked differences in virulence on host plants. When infiltrated into tobacco leaves, virulent strains caused a rapid localized necrotic response (within 24 to 48 h) characteristic of the hypersensitive response (HR), whereas nonpathogenic strains did not. Concentrated cell-free culture supernatants (CCS) from virulent strains caused a necrotic reaction on tobacco, whereas CCS from nonpathogenic strains did not. The necrosis-inducing activity was heat stable and protease sensitive. Inhibitors of eukaryotic metabolism suppressed the necrotic reaction of tobacco to CCS. No necrotic response was observed when host plants were infiltrated with either cells or CCS from virulent strains. HR-inducing protein(s) from a virulent strain separated from the majority of other proteins on DEAE cellulose at 250 to 300 mM NaCl. Ammonium sulfate-precipitated proteins from a virulent strain produced a necrotic reaction at a total protein concentration of 18 mug/ml, whereas those from a nonpathogenic strain did not, even at a concentration of 180 mug/ml. We conclude that virulent strains of C. michiganensis subsp. sepedonicus elicit a typical HR in tobacco and secrete proteinaceous elicitor(s) of the nonhost HR.

An investigation of the cause of death from cancer.

Four thousand seven hundred twenty-eight autopsies performed at the Roswell Park Memorial Institute were reviewed to determine causes of death from cancer. The duration of the disease from the date of diagnosis to death, the primary site of the tumor, a detailed description of the presence or absence of metastatic tumor at a series of sites, and an estimate of the total tumor mass were included in the evaluation. Twenty-three common primary sites were selected for investigation. These sites represented 99% of the total series. Nine causes of death were described. These were respiratory failure, infection, toxic drug reaction, hepatic failure, renal failure, shock or heart failure, adrenal gland failure, electrolyte imbalance, and central nervous system failure. Some of these associations were obviuosly due to the direct destruction of the organ in question. There are some differences, however, comparing lung lesions to hepatic lesions. These and other factors are recited in the text.