MAIN CONTRIBUTIONS

- Discovery of DNA denaturation (1951) *

- Thomas-Bertani effect: demonstration of a direct block of viral replication by the repressor responsible for immunity in temperate bacteriophages (1964).

- The transfer of information from a DNA molecule to its two daughter-molecules does not involve its transit via a specific protein that would carry all this information (1967).

- Trans-activation (initially called trans-induction) of proviral genes (1965)**. This permitted to demonstrate (in parallel with E. Englesberg, working on another system, and with W. Dove) the existence of positive control in biological systems (temperate bacteriophages), 1965.

- Elaboration of a method of logical analysis of complex biological networks (1970 - now).
Extension of the concept of feedback circuit. Its use in biology (viral development, cell differentiation, memory) and in nonlinear dynamics (1976 - now). The main contribution in this field are probably the notions that: 1) positive circuits are a prerequisite for multistationarity (and hence for differentiation and memory) and 2) negative circuits are required for the existence of an attractor, punctual (stable steady state), periodic (limit cycle) or chaotic (and thus homeostasis, with or without oscillations).

- Nonlinear dynamics can be revisited in terms of circuits. Much of the behaviour of complex systems can be disentangled by an appropriate examination of the Jacobian matrix.

* see R.Thomas, Ph.D (1952), and ref. 2, 7, 10 and 11 in the complete list of publications. See also Holmes, F. L., "Meselson, Stahl and the Replication of DNA: a History of "The most beautiful Experiment in Biology" ", Yale University Press, pp 284-285.
** trans-activation was re-discovered many years later by animal virologists: see Calendar, Biotechnology, 4 (1986) 1074-1077.