The case for the anticode

The present paper will focus on the developments in our lab related to the origin of the code since the Israel meeting (1,2). Principally these items are: (a) a new set of correlations (3) which include ranked hydrophobicities of amino acids and dinucleotides; (b) binding constants (4) of Phe for the four mononucleotides; and (c) binding constants (5) of Phe, Leu, Ile, Val, and Gly for polyadenylic acid (poly A). The data continue to support a model for the origin of the code based on relationships between amino acids and their anticodons.     

Aminoacyl-nucleotide reactions: Studies related to the origin of the genetic code and protein synthesis

In the present paper, we report on the effect of pH and carbonate on the hydrolysis rate constants of N-blocked and free aminoacyl adenylate anhydrides. Whereas the hydrolysis of free aminoacyly adenylates seems principally catalyzed by OH^–, the hydrolysis of the N-blocked species is also catalyzed by H⁺, giving this compound a U-shaped hydrolysis vs. pH curve. Furthermore, at pH's<8, carbonate has an extreme catalytic effect on the hydrolysis of free aminoacyl-AMP anhydride, but essentially no effect on the hydrolysis of N-blocked aminoacyl-AMP anhydride. Furthermore, the N-blocked aminoacyl-AMP anhydride is a very efficient generator of peptides using free glycine as acceptor. The possible significance of the observations to prebiological peptide synthesis is discussed.     

Ca entry upon depolarization of nerve

The data reviewed and the experiments presented show that a steady depolarization of a squid giant axon membrane leads to a large but transient Ca entry that is virtually totally dependent upon [Na]i. Since conventional membrane channels do not behave in this way whereas a countertransport reaction is defined as one requiring the participation of ions on opposite sides of the membrane, it is considered reasonable to identify the Ca entry that has been measured as a Na/Ca exchange. Since the enhanced Ca entry is initiated by a reduction in membrane potential, a further conclusion is that the Na/Ca exchange reaction involves a non-electroneutral exchange of changes. The physiological importance of these findings of a Nai-dependent Ca influx in nerve may be that it assures larger Ca entries following rapid tetanic stimulation (because of the increase in Nai) and this may be necessary to produce a Cai signal that is detectable over the increased Cai background as a result of the tetanic stimulation. In smooth and cardiac muscle, increases in Nai surely play a regulatory role in increasing Ca entry with depolarization and hence in increasing tension.     

Transgenic animals as models for human diseasereport of an EC Study Group

ContributorsThis report results from the discussion of an Expert Group convened in Edinburgh on 29–30 October 1992 for a workshop on that subject sponsored and organized by the Commission of the European Communities, Directorate General XII (CEC-DG XII). The experts taking part in the workshop were: R. Lathe and J.J. Mullins, Coordinators (AFRC Centre for Genome Research, University of Edinburgh); G.N. Fracchia, Secretary (Medical Research-Pharmaceuticals, CEC-DG XII, Brussels); and the participants; C. Babinet (Dept d'Immunologie, Institut Pasteur, Paris); P. Eliard (EFPIA, Brussels); C. Benoist (LGME du CNRS/INSERM, Strasbourg); G. Bianchi (Ospedale San Raffaele, Universita di Milano, Milan); E. Boncinelli (DIBIT, Ospedale San Raffaele, Milan); G. Brem (Universitat München); G. Cossu (Institute of Histology, School of Medicine, University of Rome); N. Dillon (MRC National Institute for Medical Research, London); V. Episkopou (Dept of Biochemistry & Molecular Genetics, St Mary's Hospital Medical School, London); M. Evans (Wellcome/CRC Institute, Cambridge); R. Forster (Italfarmaco Research Centre, Cinisello Balsamo, Milan); D. Ganten (Max-Delbrück-Zentrum für Molekulare Medizin, Berlin); A. Gossler (Max-Delbrück-Laboratorium in der Max-Planck-Gesellschaft, Köln); J. Gray (Dept Psychology, Institute of Psychiatry, London); R. Hammer (Howard Hughes Medical Institute, University of Texas, Dallas, USA); A. Hobden (Genetics Unit, Glaxo Group Research Ltd, Middlesex); G. Kollias (Laboratory of Molecular Genetics, Hellenic Pasteur Institute, Athens); D. Lamy (Transgène SA, Strasbourg); D. Lincoln (MRC Reproductive Biology Unit, Edinburgh); J. Mallet (CNRS/LNCM, Gif-sur-Yvette); D. Melton (ICMB, University of Edinburgh, Edinburgh); J.M. Moalic (U127 INSERM, Hôpital Laraboisire, Paris); S. Mockrin (Dept Health & Human Services, National Institutes of Health, Bethesda, MA, USA); J. Ottesen (Biopharmaceuticals Division, Dept of Gene Technology and Virology, Novo Industrie, Denmark); D. Porteous (MRC Human Genetics Unit, Western General Hospital, Edinburgh); P. Rae (Pharmaceutical Division, Miles, West Haven, USA); F. Theuring (Schering AG, Pharmaceutical Research, Berlin); G. Tremp (Rhone-Poulenc Rorer SA, Centre de Recherche de Vitry-Alfortville, Vitry-sur-Seine); H. Van der Putten (Dept Biotechnology, Ciba-Geigy AG, Basel); R. Wolf (ICRF Molecular Pharmacology Group, Biochemistry Dept, Edinburgh). Further supporting documentation and commentary were received from P. Dement (Amsterdam), U. Habenicht (Berlin), P. Grüss (Gottingen), M. Lyon (Oxford), C.C.J. Miller (London), W.-D. Schleuning (Berlin) and R. Williamson (London) and their contributions are gratefully acknowledged.     

Preparation of Coenocytes for Freeze-Etching

Successful freeze-etching of a coenocyte has been accomplished with giutaral-dehyde stabilization followed by infiltration with cryoprotectant. Hyphae of the coenocytic water mold Achlya were stabilized with 5% glutaraldehyde in phosphate buffer. Gradual infiltration by dropwise addition of the cryoprotectant (25% glycerol, 10% ethylene glycol, distilled water, v/v) is accomplished over a period of 8-10 hr on a shaker. Subsequent freeze-etching is carried out by standard procedures.     

NUTRITION AND SEXUAL REPRODUCTION IN THE WATER MOLD ACHLYA

The entire sexual reproductive progression in the heterothallic water mold Achlya ambisexualis Raper occurs in the absence of exogenous nutrients. Mated male and female mycelia, previously grown on a chemically defined medium, can utilize endogenous materials for the formation and maturation of sexual reproductive structures. Under these conditions the initiating sexual hormone antheridiol, produced by the female, exerts its morphogenetic effect on male mycelium in the absence of exogenous nutrients.