STREPTOCOCCAL L FORMS V. : Acid-Soluble Nucleotides of a Group A Streptococcus and Derived L Form.

Edwards, John (University of Illinois College of Medicine, Chicago, and Albert Einstein Medical Center, Philadelphia, Pa.) and Charles Panos. Streptococcal L-forms. V. Acid-soluble nucleotides of a group A Streptococcus and derived L form. J. Bacteriol. 84:1202-1208. 1962.-This report deals with a comparison of the acid-soluble nucleotides from a group A, type 12, beta-hemolytic streptococcus and a derived stable L form. This is the first report of the presence of a cell-wall precursor (uridine diphosphate-muramic acid-peptide) in a stable L form. Cells of each organism were obtained during their logarithmic phases of growth, harvested by centrifugation, and washed with osmotically protective NaCl solutions. The analytical procedures were essentially those of Franzen and Binkley. Calculated values indicated that these results could not be accounted for by dry-weight differences due to loss of the streptococcal cell wall. It was found that both organisms contained the same amount of total nucleotide material. The L form contained no uridine monophosphate (UMP), a large concentration of uridine diphosphate (UDP)-muramic acid-peptide, and a significant increase of UDP-N-acetylglucosamine. A similar nucleotide containing muramic acid-peptide was not demonstrable in the parent coccus. Instead, UMP and an unidentified uridine nucleotide were resolved in this region. Analyses of extracts from this streptococcal L form indicate the probable presence of two of the three nucleotides originally isolated by Park from penicillin-treated Staphylococcus aureus. The presence of the UDP-muramic acid-peptide cell-wall precursor in the L form cultured in the continual absence of penicillin points to an inability of this form to resynthesize the rigid cell wall and indicates that this synthetic mechanism has been permanently impaired.     

BIOASSAY SYSTEMS FOR THE PYRETHRINS: V. EXPERIMENTS WITH A RESISTANT STRAIN OF CALANDRA GRANARIA L.

Some principles of testing for resistance in wild and laboratory stocks of insects are discussed, and experiments with Calandra granaria L. are described in which these insects are selected for pyrethrum resistance.
A new method is described of expressing relative tolerances when the relevant regression lines are not parallel, based on the 'generalized distance' of Mahalanobis. The method may equally be used for the comparison of two insecticides giving rise to lines of different slope. A limited increase in resistance occurred on selection. Non-random oscillatory sequences of slopes were observed when the resistant strain was assayed, and regression parameters computed. The nature of these oscillations is considered.