The inherent erodibility of twenty soils was indexed using Middleton's dispersion ratio and Anderson's surface‐aggregation ratio. These indices were then used as dependent variables for several regression analyses. The milliequivalents per 100 grams of oven‐dried soil for the four most plentiful soil cations (Ca, Mg, K, and Na) were determined and then used as independent variables in the regressions.
The best fit to the data was found to be an equation of the type:
Both the linear and the curvilinear terms were significant at the arbitrarily selected 5 per cent level.
The toxin produced by Clostridium botulinum type A is a well-known and a well-studied neurotoxin but not many of these studies have correlated the morphological changes of the bacteria with toxin production. Toxin production in type A has been related to autolysis as well as carbohydrate source. Furthermore, toxin production can be inhibited or eliminated if growth occurs in the presence of ethylenediamine tetraacetic acid (EDTA). During the past year we have attempted to use the scanning electron microscope for this correlation of toxin production with morphology under varying conditions of cultivation.
Plasma clotted with RVV (1 mg/L) for 90 minutes loses 60% of the measurable prothrombin. Batch adsorption of the serum with DEAE-cellulose followed by hydroxyapatite chromatography and gel filtration on Sephadex G-200 yields 4 mg/L of Fragment F1.2, the prothrombin NH2-terminal activation peptide of mass = 35,000 daltons. Identification is based on migration on SDS acrylamide electrophoresis and the ability of small amounts of thrombin to cleave F1.2 into F1 and F2.The presence of Fragment F1.2 after clotting plasma in this manner demonstrates that the average amount of thrombin present during clotting was less than 1 u/ml. This fact in combination with 60% prothrombin consumption indicates that the thrombin formed is inactivated in less than one minute.F1.2 is soluble in 0.9 M perchloric acid, as are F1 and F2. This property may simplify the purification process and allow quantitation of F1.2 release during clotting.
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