The title to the talk this afternoon, “Abiogenic Information Coupling, or, How protein and DNA were married”, is, indeed, an excerpt from the much broader subject to which your President referred, namely chemical evolution of life on the surface of the earth, with some speculation about elsewhere as well. Actually, the “elsewhere” portion is more than a hopeful addition because it may provide a check on the speculations on the origin of life on the surface of the earth, which is very difficult to obtain inany other way.

Studies have been made on the incorporation of [8H]-deoxythymidine into the DNA of the livers of Rana catesbeiana tadpoles. When metamorphosis was induced with tri-iodothyronine, the specific activity of the nuclear DNA rose 5 days after administration of the hormone. In contrast, the specific activity of the DNA from the mitochondrial fraction rose grave–2 days after hormone administration.

In order to determine whether the in vivo change was due to alterations in the pool sizes of the DNA precursors, in vitro studies on DNA polymerase were carried out. It was found that under conditions where the enzyme activity was not limited by availability of template or substrates, there was a rise in the DNA polymerase activity in crude cell extracts from the tadpole liver. Fractionation of the cell components showed that little of this increment in activity appeared to be located in the nucleus, but that a large percentage alteration in activity occurred in the mitochondrial and cell sap fractions.

A possible interpretation of these results is that an increase in the mitochondrial DNA polymerase is one of the early effects of thyroid hormone. This possibility is discussed in relation to the other known effects of thyroid hormones in tadpoles, with particular reference to nucleic acid metabolism and also to mitochondrial hyperplasia.

Classical immunology grew out of the observation that patients who recovered from certain infectious diseases like plague and smallpox rarely contracted the same disease again. The early development of the subject was largely stimulated by the fact that many patients died during the initial attack, and the consequent need for developing methods of prevention, diagnosis and treatment.

It Is the general object of this paper to consider which of the many actions of anti-lymphocytic antibody contribute to its immunosuppressive action. However, it will be principally concerned with the kinetics of lymphopoiesis in mice receiving anti-lymphocytic antibody and the relevance of this activity to the resulting immunosuppression.

During recent years the heterogeneity of equine antibodies to a variety of antigens has been convincingly demonstrated (Rockey, Klinman and Karush 1964; Raynaud, Iscaki and Mangalo 1965; Allen, Sirisina and Vaughan 1965; Klinman et al. 1966; Klinman and Karush 1967; Johnson and Allen 1968). For example, extensive studies on equine anti-hapten antibodies have shown that the IgG fraction of horse serum contains at least four different proteins, namely the IgGa, IgGb, IgGc and IOS IgG globulins in addition to the IgG(T) and IgM proteins (Rockey et al. 1964; Klinman et al. 1966). These antibodies differ widely in their ability to precipitate the protein-bound hapten and to fix complement, and their concentrations and binding affinities vary considerably during a course of immunization (Klinman et al. 1966).

The fundamental problem in transplant surgery is that of preventing the immunological reaction which invariably occurs when an organ is transplanted between individuals, other than identical twins, and which brings about the destruction of the transplant. This reaction can be suppressed by a variety of agents but none of them is entirely satisfactory and there is a great need to find new ones which will be more effective and, in particular, more specific in their action. It was for this reason that anti-lymphocytic serum was first developed.

The Wellcome Foundation is part of the M.R.C. Working Party on A.L.S. and the main role of the Foundation, as agreed with the Working Party as a whole, is to produce A.L.S. on a large scale for use in man.

In Great Britain, the use of any new therapeutic agent is controlled by authority, in this case the Dunlop Committee. Before this committee could be approached for a licence to market such a product, it would be necessary for the pharmaceutical company concerned to have established conditions for large-scale production.