Binding of the purified type C 75 (neurotoxin), 125 and 165 botulinum toxins to epithelial cells of ligated small intestine or colon of the guinea pig (in vivo test) and to pre-fixed gastrointestinal tissue sections (in vitro test) was analysed. The 16s toxin bound intensely to the microvilli of epithelial cells of the small intestine in both in vivo and in vitro tests, but did not bind to cells of (2 x lo5 MLD) was injected, little toxin activity was detected in the sera.Therefore, the haemagglutinin of type C 16s toxin is apparently very important in the binding and absorption of botulinum toxin in the small in test i ne.1

Yersinia enterocolitica is capable of growing in a broad range of temperatures from 4 to 45 C. How this organism alters its membrane lipids in response to the change of growth temperature is very interesting. The fatty acids of membrane lipids of cells cultured at 5, 15, 25 and 37 C were analyzed and the physical states of these membrane lipids were characterized. The major phospholipids of this bacterium were phosphatidylethanolamine, phosphatidylglycerol, cardiolipin, lysophosphatidylglycerol and lysophosphatidylethanolamine.No significant difference in phospholipid composition in response to culture temperatures was observed. It was reported in our previous paper that the major fatty acids of membrane phospholipids of Y. enterocolitica were C15: 0, C16:0, C16: 1, cyclopropane C17: 0 and C18: 0. Some differences in the fatty acid composition were, however, observed with the change of culture temperature. When the culture temperature was raised, the saturated and cyclopropane fatty acids substantially increased and the unsaturated ones decreased. A. reverse phenomenon was observed when culture temperature was lowered. From the viewpoints of membrane physical state, adaptational changes were analyzed using a nylon microcapsule method. Phase transition in membrane lipids of cells grown at each culture temperature took place in the range of about 5 C below and about 10 C above the culture temperature.It is, therefore, considered that Y. enterocolitica maintains its membrane rigidity and fluidity in response to growth temperature by changing the membrane fatty acid composition.

The cells of Helicobacter pylori were suspended in the medium containing 35S-methionine. After a heat shock of the cells at 42 C for 5, 10, and 30 min, the production of proteins was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Out of many proteins produced by the cells, only 66 kDa protein production was dramatically increased by heat treatment. The N-terminal amino acid sequence of 66 kDa protein was quite similar to that of 62 kDa and 54 kDa proteins previously suggested as heat shock protein (HSP) of H. pylori based on the reaction with polyclonal and monoclonal antibodies against HSP 60 family proteins produced by other bacteria. Therefore, it was concluded that H. pylori produces the 66 kDa protein as its major heat shock protein which belongs to HSP 60 family.

The authors measured the osmotic stability of liposomes prepared with membrane lipids of bacteria, using the osmotic-shock release of entrapped carboxyfluorescein as an indicator.The sub-second physical changes of liposomes suspended in a solution of low osmotic pressure were examined by stopped flow spectrophotometry. The entrapped carboxyfluorescein was released when the liposomes burst on inflow of excess water.Liposomes prepared with the lipids of a stable Staphylococcus aureus L-form strain were more resistant to low osmotic pressure than those prepared from the wild strain of S. aureus, and liposomes prepared from Mycoplasma orale were even more resistant.Cardiolipin enhanced the lipid membrane stability in S. aureus and cholesterol in M. orale. The stability of lipid membranes to low osmotic pressure could be precisely determined by the present method.

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