Degradation of ribosomal RNA from Escherichia coli by ribonuclease U2 and in vitro transcription of "RNA-fragments" into complementary DNA]

Under well defined conditions ribosomal RNAs purified from Escherichia coli can be degraded by ribonuclease U2 giving rise to RNA fragments of 60--70 nucleotides. In vitro, these fragments are efficiently transcribed into a complementary DNA by DNA polymerase RNA dependent, partially purified from extracts of E. coli. In vivo, "RNA-fragments-U2" inhibit the development of plant tumors.     

Spatial conformation of human serotransferrin glycans]

The construction of molecular models for the human serotransferrin glycans shows that they present one compact section linked to the protein and constituted by the pentasaccharide alpha-Man-(1 leads to 3)-[alpha-Man-(1 leads to 6)]-beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc-(1 leads to)-Asn to which are attached two "antennae" consisting of the trisaccharide alpha-NANA-(2 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc. The trisaccharide sequence beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc adopts a flat and rigid conformation, stabilised by hydrogen bonds. In contrast, the sequence alpha-NANA-(1 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc-(1 leads to 2)-alpha-Man takes up a helical configuration. The two "antennae" can be disposed on the pentasaccharide core to give two possible configurations, one Y-shaped and the other T-shaped. In both cases, the general conformation of the glycans is perfectly compatible with their postulated role as a recognition signal.     

New lectin receptors in carcinoembryonic antigen (CEA).

The glycoprotein CEA (carcinoembryonic antigen) carries carbohydrate groups, which react with the plant lectins from Agaricus bisporus, Arachis hypogaea (peanut), with Tridacnin from invertebrate clams and with the anti-A lectins from snails. Accordingly, it has cryptantigenic structures, which correspond to the T or T-like antigen, the Tridacnin receptor and to the so called A-like antigen.     

Hypnotic effect of serotonin administered in the vago-aortic afferent pathway

A minute amount of serotonin injected in the nodose ganglion circulation area develops abrupt myosis and general electrocortical synchronization activity in "encéphale isolé" Cat preparation. This hypnogenic effect of serotonin can still be reproduced after transection of vago-aortic nerves caudally to the nodose ganglia. The same injections become ineffective after rostral transection of the same pathway. These results suggest that serotonin may trigger some signs of sleep through peripheric nervous elements in which are probably localized in the nodose ganglia.     

Epithelial-mesenchymal interaction in differentiation of duodenal epithelium of fetal rats in organ culture

Summary Epithelial-mesenchymal interaction in the differentiation of duodenal epithelium of fetal rats was investigated by recombination experiments in vitro. The proportion of goblet cells in duodenal epithelium was significantly greater on recombination of developing duodenal epithelium with mesenchyme of the glandular stomach than on recombination with that of the duodenum. Mesenchyme of the glandular stomach or forestomach was better than duodenal mesenchyme in supporting morphogenesis of duodenal epithelium. Treatment of tissues with N-methyl-N-nitro-N-nitrosoguanidine (MNNG) did not affect these tissue interactions.This work was supported by grants-in-aid for cancer research from the Ministry of Education, Science and Culture, Japan.Acknowledgment. The authors wish to express their gratitude to Prof. T. Mizuno of the University of Tokyo for valuable suggestions.     

Down's syndrome: changes in protein fractions of blood plasma

Summary A statistically significant decrease of prealbumin and statistically significant increases of alpha₂-macroglobulin and IgA were found in blood plasma of patients with Down's syndrome using quantitative crossed immunoelectrophoresis.We are indebted to Prof. T.C. Bøg-Hansen, University of Copenhagen, for the helpful discussion of our results.     

Examination of naturally occurring polyacetylenes and α-terthienyl for their ability to induce cytogenetic damage

Summary -Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither -terthienyl nor phenylheptatriyne induced chromosome aberrations.The authors wish to thank the National Science and Engineering Research Council for financial support of this research.     

A selective concentration-dependent dysrhythmogenic and antidysrhythmic action of prostaglandins E2, F2α and I2 (prostacyclin) on isolated rat hearts

Summary Prostaglandins (PGs) E₂, F₂, and I₂ were examined for their effects on the electrical and mechanical activities of isolated rat, rabbit and guinea-pig hearts. All PGs produced dysrhythmias in rat hearts at low concentrations only, while higher concentrations were antiarrhythmic. Guinea-pig hearts were less responsive while rabbit hearts were completely resistant.We thank the Manitoba Heart Foundation for financial support and Dr J. Pike (Upjohn, Kalamazoo, MI, USA) for gifts of prostaglandins. Dr M. Karmazyn is a Fellow of the Canadian Heart Foundation.     

Metabolism in Porifera XII. Further informations on the biosynthesis of 3β-hydroxymethyl-A-nor-steranes in the spongeAxinella verrucosa

Summary Direct incorporation and cold trap experiments suggest that cholest-4-en-3-one is an intermediate in the conversion of cholesterol into 3-hydroxymethyl-A-nor-cholestane in the marine spongeAxinella verrucosa. Cholest-4-en-3-one is further transformed by the sponge into cholest-4-en-3-ol, 5-cholestan-3-one and 5-cholestan-3-ol; these compounds arise from side reactions, which are not part of the major metabolic route leading to 3-hydroxymethyl-A-norsteranes.     

The induction of chromosome aberrations in human lymphocytes by negative π-mesons under conditions of anoxia and oxygenation

Summary After a dose of 3.0 Gy in the peak position of the pion depth-dose curve, the ratios between observed chromosome aberration yields under conditions of oxygenation and of anoxia were obtained for lymphocytes exposed at 3 depths in a plastic phantom. These ratios were 3.7, 1.9 and 1.3 in the plateau, peak and post-peak positions, respectively, suggesting a corresponding decrease in the oxygen enhancement ratio.Acknowledgments. We wish to thank Dr D.H. Reading, Mr M.A. Hynes and Mr W. Spinks for their assistance at the Rutherford Laboratory's -II beam line. This work was partly supported by Euratom Contract 171-76-1 BIO-UK.