Degradation of collagen by the cariogenic bacteria, Streptococcus mutans

The behaviour of cariogenic Bacteria (Streptococcus mutans) is studied with regard to collagen, which represents 90% of the dentine organic matrix. Collagenase activity of cariogenic Bacteria is measured with radioactive precursors and gel electrophoresis and compared to reference bacterial collagenase (Clostridium histolyticum). Labelled collagen substrate has been prepared with two different methods: extraction by 0,5 M acetic acid from young Rat skin, previously labelled with L-proline 14C, or reduction by Na B3H4. Both collagen sutstrates have been incubated for 2 h in Terleckyj medium in which the Streptococcus mutans have been inoculated. The experiments show a proteolytic activity of Streptococcus Mutans on the collagen substrate.     

Unexpected antibiotic properties of a cephalosporin]

The presence of an oximino group on the methylene of the (2-aminothiazol 4-yl)-acetyl side chain bound to the 7-amino cephalosporanic acid affords derivatives with syn or anti configuration. Whereas the anti isomers display low antibiotic activities, the syn isomers possess a surprising high efficiency against gram negative bacteria, enhanced a factor of 10 to 100 as compared with the cephalosporins known at the moment.     

Inhibition of methanol metabolism in mice with acetyl salicylic acid

Zusammenfassung Acetylsalicylsäure hemmt die Oxydation von Methanol und Formiat in vivo erheblich, die Katalase nur in vitro, und vermindert den toxischen Effekt der Methanolvergiftung. Der Mechanismus der Methanoloxydationshemmung durch Acetylsalicylsäure könnte eher auf die Verminderung des Peroxyd-Pooles — als die Katalasehemmung — zurückzuführen sein.     

Speed of in vitro reassociation of gonadotropin subunits in a teleost fish, the carp (Cyprinus carpio L.)]

Purified gonadotropin subunits of a teleost Fish, the Carp, reassociated in vitro, according to a second order rate reaction. The rate constant was temperature dependent. Compared to ovine LH, the Q10 was about three times less and the rate constant much greater (160 times for instance at 20 degrees C). The possible physiological significance of these differences is underlined.     

Fine structure of differentiated chromosome segments during the meiosis of pollen mother cells of Allium cepa

Summary Differentiated chromosome segments were observed during studies of pollen mother cells of A. cepa during the first meiotic division. Their structure is like those of the nucleolar organizing region (NOR) described in A. cepa microspores. It is suggested that these differentiated chromosome segments correspond to the secondary constrictions seen under the optical microscope.