Cloning of Shiga-like toxin structural genes from a toxin converting phage of Escherichia coli

The genes controlling high-level production of Shiga-like toxin (SLT) in Escherichia coli were cloned from the SLT converting phage 933J. This phage was isolated from a strain of E. coli that caused a foodborne outbreak of hemorrhagic colitis. The genes that convert normal E. coli to organisms producing high levels of toxin were cloned into the plasmid pBR328 and expressed in E. coli HB101. DNA restriction mapping, subcloning, examination of the cloned gene products by minicell analysis, neutralization, and immunoprecipitation with antibodies to SLT were used to localize the toxin converting genes and identify them as structural genes for SLT. Southern hybridization studies established that the DNA fragment carrying the cloned toxin structural genes had homology with the DNA of Shigella.     

Magnetoglow: a new geophysical resource

Evidence has been found that the earth is immersed in a large volume of glowing helium ions. This ionic glow, at 304 angstroms, is similar to the geocoronal hydrogen glow in that it extends to very high altitudes, but it is unique in that it is largely confined to the closed field line portion of the magnetosphere. Because of its magnetic containment, this ionic radiation is called the "magnetoglow." Observations of the magnetoglow from inside and outside the magnetospheric cavity promise to provide a valuable means of studying the structural dynamics of the magnetosphere.     

Alpha 2-antiplasmin Enschede: alanine insertion and abolition of plasmin inhibitory activity

An abnormal alpha 2-antiplasmin that is associated with a serious bleeding tendency has been found in a Dutch family and is referred to as alpha 2-antiplasmin Enschede. This abnormal alpha 2-antiplasmin is converted from an inhibitor of plasmin to a substrate. The molecular defect of alpha 2-antiplasmin Enschede, as revealed by sequencing of cloned genomic DNA fragments, consists of an alanine insertion near the active site region of the molecule. Substitution of this fragment into complementary DNA for a wild-type alpha 2-antiplasmin yields a translation product with physical and functional properties typical of the abnormal alpha 2-antiplasmin Enschede. The naturally occurring mutant may serve as a model for investigating the structures that determine the properties of an inhibitor versus those of a substrate in serine protease inhibitors.     

Hepatitis in marmosets: induction of disease with coded specimens from a human volunteer study

Marmosets inoculated with plasma from three early acute hepatitis patients developed hepatitis 30 to 40 days later. Other groups of marmosets receiving preinfection plasmas from the same patients showed no evidence of hepatitis in this experiment. It is, therefore, most probable that hepatitis in marmosets represented transmission of human disease rather than activation of latent "marmoset hepatitis."     

The infection of potatoes byPhytophthora infestans during simulated washing and its control using a hot water treatment

Summary A single blighted tuber released on average 1.39 mg ofP. infestans mycelia and sporangia during simulated washing. In subsequent experiments up to 100% of tubers were infected when healthy tubers were washed in a suspension ofP. infestans equivalent to a concentration of 1.65 μg ml⁻¹, i.e. that calculated to be in a commercial washing plant after washing a potato stock with approximately 1% of tubers infected with blight for 4 hours. Immature tubers were more prone to infection during washing than mature tubers. Damaging tubers, irrespective of their maturity, increased the incidence of tuber infection. The viability ofP. infestans isolates was significantly reduced byin vitro immersion in water at 44°C for 5 minutes. The infection of daughter tubers dipped in a suspension ofP. infestans for 3 minutes was prevented when the suspension temperature was 44°C. There was no indication of tuber damage at this temperature.