C. Blomberg; Actual Projects

1. Modelling of biological network processes. Aspects of stability and random influence

Chemical reactions in living cells comprise complex networks with important control (feedback) mechanisms. It is also suggested that cells by the possibilities of evolution can reach optimal levels for essential processes. To analyse this properly, mathematical modelling is essential. Because of the complexity, an influence of a foreign substance is seldom straight-forward. Further, a proper function can be destroyed by random influences, but sometimes random influences are essential for creating a necessary activity. Possibilities to reach optimal results may also depend on such effects.

We have previously investigated the accuracy of synthesis processes and factors that may influence it. A project under this title is going with an aim to understand the response to free radicals in the cells. In another project we investigate what can be achieved by spontaneous generation of nerve impulses by random influences. One question here is whether living systems and, in particular, the neural system can systematically use random processes and even generate chaotic behaviour for an optimal performance. In connection with these problems, we also investigate the effect of noise in simpler model systems, governed by non-linear dynamics.

2. Physical problems concerning diversity and the occurrence of function in the Origin of Life.

How did life start on Earth? This is a question that has concerned mankind as far back as there is written evidence and probably much longer than so. The idea nowadays is that life occurred spontaneously on Earth after a number of steps. In the first steps various organic molecules were formed, then these could be bound together to polymers. Some polymers, in particular peptides, consisting of amino acids, could achieve catalytic properties and support further steps. A necessary major step was the appearance of replicators, polymers that could be copied as present days nucleic acids, DNA and RNA. There are still severe problems to understand a spontaneous occurrence of replicators, but with these and the combination of peptides and amino acids, a systematic synthesis of proteins that was based upon information the replicators could be developed. Then, the way to real life was wide open.

Most of that is chemistry with several still unsolved problems. However, to understand the occurrence of the first living organisms, it is not sufficient to understand how organic molecules could be formed, it is also necessary to understand how these could function together and evolve to a functioning living cell. To understand that, one must use information about these molecules and ideas how they function. There are few direct experiments that can be done to elucidate the situation. There are a number of problems that can be regarded as moment22-situations or hen or egg-problems. One such problem concern the appearance of DNA as a giant information-carrier. At an early stage, one may imagine a number of free genes, but DNA gave an advantage by collecting all genes at one place. Chemically that would not be to difficult to accomplish, but the problem is that such a large molecule required a number of controlling proteins to keep track of the information and to make sure that the large DNA-moleucdles were copied with a high accuracy. DNA could not have worked sufficiently efficient without such controlling proteins, but that controlling function had no meaning without DNA. Soothe question is: how did they arise, DNA and its controlling proteins. Could they have occurred simultaneously? Or were the controlling proteins there, but had another function?

Mathematical modelling and physical reasoning provide valuable information about the occurrence of organization and stages in the origin of life which are otherwise not amenable to experimental studies. In that way, we get an understanding of the steps that must have preceded the occurrence of life and, with that, a wider understanding of Life itself.

In particular, we are interested in questions about how stability and also a rich diversity could be reached. Life as today shows a very high stability, but this is accomplished by a rich biochemical controlling machinery. A big question is how this was achieved at the onset. Also, even the first
cell that occurred must have had a large number of functions. Still, models for understanding these steps do not easily explain how such a diversity
could have arisen.

These studies are closely related to the field of "Artificial Life", which aims to understand features of life by studying artificial, mainly abstract systems with many of the features of real life. Again, stability questions are crucial for these systems.