Osmotic Fragility of Lysozyme- and Thiol-Treated Lactobacillus plantarum

Reduced but not oxidized thiols increased the sensitivity of lysozyme-treated cells of Lactobacillus plantarum to lysis by osmotic shock.     

Effect of Sublethal Heat on the Metabolic Activity of Staphylococcus aureus

Cells of Staphylococcus aureus MF-31 which have been heat-injured at 52 C have an altered metabolic activity. Analyses of whole-cell preparations by means of the Thunberg technique and Warburg manometry showed decreased dehydrogenase activity and oxygen uptake on a variety of substrates. In cell-free extracts prepared from injured cells, it was demonstrated that the specific activity of fructose diphosphate aldolase, lactate dehydrogenase, and butanediol dehydrogenase was less than that of extracts prepared from normal unheated cells. Recovery of the heat-injured cells in a suitable medium supported a return of the dehydrogenase activity and oxygen uptake, but the activity of the enzymes in cell-free extracts prepared from such partially recovered cells did not fully return to the level of normal (unheated) preparations. Addition of chloramphenicol or actinomycin D to the recovery medium, singly or in combination, retarded the return of the normal metabolic activity. Radiorespirometric experiments indicated that the percentage participation of the Embden-Meyerhoff Parnas and hexose monophosphate pathways remained the same for normal and heat-injured cells. The sublethal heat treatment decreased the catabolic capabilities of S. aureus and the production of selected end products associated with the metabolism of glucose.     

The co-ordination between respiration and wing beats in birds

Summary Investigations in 10 species showed that respiration of birds in flight is usually co-ordinated with wing beats, but the co-ordination is not obligatory. Respiration synchronous with wing beats (11 co-ordination) was found only in pigeons and crows, the other species exhibited one of 11 other types of co-ordination. Quails, ducks and pheasants, birds with relatively high wing beat frequencies (with relatively small wings) showed a 51 co-ordination. Within species, and even during a flight the type of co-ordination changed, and simultaneously there were sudden changes in the respiration frequency. For the most part, the beginning of inspiration was linked with the (end of) upstroke and the beginning of expiration with the end of downstroke.Issued as N.R.C.C. No. 11095Dedicated to Prof. Dr. Erwin Stresemann at his 80. birthday.We are grateful to Dr. D. Jensen for enabling the work on the gulls at McMaster University in Hamilton. We also wish to thank B. A. Mackenzie and R. Charbonneau for the skillful assistance in all experiments.     

New data on the toxic and radioprotective effect of cysteine onEscherichia coli 15 T- cells

Summary Exponential phase cultures ofE. coli 15 T^- cells growing on glucosemineral medium were supplemented with 2 mM l-cysteine-HCl. The optical density, acid soluble SH (AS-SH) as well as the DNA, RNA, and protein synthesis of the cultures were examined during this treatment and after return to normal growth conditions. Similarly, the survival of cells irradiated by a standard X-ray dose in cysteine-free buffer was measured.The development of radioresistance during the cysteine treatment as well as the loss of this acquired radioresistance after return to normal growth conditions could be divided into two phases: a) an instantaneous and b) a slow change of radioresistance. Phase a seems to be related to the changes occurring in the AS-SH content of the bacteria, while phase b is apparently dependent on the alterations in the synthesis of macromolecules.This work was partly presented at the 6th Annual Meeting of the European Society for Radiation Biology, Interlaken 1968.     

Studies in lipid histochemistry

Summary It was shown by experiments with staining reactions performed in situ in blood smears of adults and children, in sections prepared by various procedures, in spot tests, and by chromatographic examination of extracted lipids that haemoglobin is responsible entirely for the staining of red blood cells in the acid haematein test and for the greater part for the staining in the OTAN reaction. The acid haematein test is from the point of view of lipid histochemistry neither specific nor sensitive. On the other hand the OTAN reaction is sensitive although it is not specific. It is concluded that the extraction test with chloroform-methanol must always be performed when the lipidic nature of the demonstrated substance(s) is to be proved unequivocally and that the non-lipidic nature of the residual staining must be always considered.