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Physicist Claudius Gros on the journey of an automated gene laboratory to celestial bodies outside our solar system
FRANKFURT.Can life be brought to celestial bodies outside our solar system which are not permanently inhabitable? This is the question with which Professor Dr. Claudius Gros from the Institute of Theoretical Physics at Goethe University Frankfurt is dealing in an essay which will shortly appear in the scientific journal Astrophysics and Space Science.
Over the last years, the search for exoplanets has shown that very different types exist. “It is therefore certain that we will discover a large number of exoplanets which are inhabitable intermittently but not permanently. Life would indeed be possible on these planets, but it would not have the time to grow and develop independently”, says Gros. Against this background, he has investigated whether it would be possible to bring life to planets with transient habitability.
From a technical standpoint, the Genesis mission could already be achieved within a few decades with the aid of interstellar unmanned micro spacecraft which could be both accelerated and slowed down passively. On arrival, an automated gene laboratory on board the probe would synthesize a selection of single-cell organisms with the aim of establishing an ecosphere of unicellular organisms on the target planet. This could subsequently develop autonomously and possibly also into complex life forms. “In this way, we could jump the approximately four billion years which had been necessary on Earth to reach the Precambrian stage of development out of which the animal world developed about 500 million years ago”, explains Gros. In order not to endanger any life which might already be present, Genesis probes would only head for uninhabited exoplanets.
The mission’s actual duration played no role in the Genesis project, since the time scales for the subsequent geo-evolutionary development of the target planet lies in the range between a few tens of millions and a hundred million years. The Genesis project therefore has no direct benefit for people on Earth. “It would, however, enable us to give life something back”, says Gros. In this context, he is also discussing whether biological incompatibilities would have to be expected in the case that a second Earth fully developed in terms of evolution were to be colonized. “That seems, however, at present to be highly unlikely”, says the physicist, dampening any too high expectations.
Publication: Claudius Gros, Developing Ecospheres on Transiently Habitable Planets: The Genesis Project, Astrophysics and Space Science (in press); http://arxiv.org/abs/1608.06087
Interview with Claudius Gros: How to Jumpstart Life Elsewhere in Our Galaxy, The Atlantic, http://www.theatlantic.com/science/archive/2016/08/genesis-missions/497258/
Information: Prof. Claudius Gros, Institut für Theoretische Physik, Campus Riedberg, Tel.: (069)-798 47818, firstname.lastname@example.org.
Fundamental structural difference to earlier models
FRANKFURT.Elongated fibres (fibrils) of the beta-amyloid protein form the typical senile plaques present in the brains of patients with Alzheimer's disease. A European research team and a team from the United States (Massachussetts Institute of Technology in cooperation with Lund University) have simultaneously succeeded in elucidating the structure of the most disease-relevant beta-amyloid peptide 1–42 fibrils at atomic resolution. This simplifies the targeted search for drugs to treat Alzheimer's dementia.
Alzheimer's disease is responsible for at least 60 percent of dementia cases worldwide. It causes enormous human suffering and high costs. A cure or causal therapy are not yet available. A reason for this is that the exact course of the illness in the brain at a molecular level has not yet been adequately clarified.
It is known that the beta-amyloid peptide plays a crucial role. This peptide, 39 to 42 amino acids long, is toxic to nerve cells and is able to form elongated fibrils. Beta-amyloid peptide 1–42 and beta-amyloid peptide 1-40 are the two main forms that appear in senile plaques. We do not know why these lead to the decay of nerve cells in the brain, but this question is very interesting for the development of medications to treat Alzheimer's disease.
In a joint project between the Swiss Federal Institute of Technology in Zurich, the University of Lyon, and the Goethe University in Frankfurt am Main, in cooperation with colleagues at the University of Irvine and the Brookhaven National Laboratory, researchers have succeeded in determining the structure of a beta-amyloid peptide 1–42 fibril at an atomic resolution. This fibril presents the greatest danger in this disease. The researchers built on earlier research on the structure of beta-amyloid monomers done at the University of Chicago. Further immunological examinations show that the investigated form of the fibrils is especially relevant to the illness.
Protein fibrils are visible in electron microscope images (Fig. 1), but it is very difficult to go to an atomic level of detail. The standard methods used in structural biology to achieve this assume that the macromolecule is present as a single crystal or in the form of individual molecules that are dissolved in water. However, fibrils are elongated structures that adhere to each other and neither form crystals, nor can be dissolved in water.
Only solid-state nuclear magnetic resonance spectroscopy (solid-state NMR) is capable of offering a view at the atomic level in this case. New developments in methods made it possible to measure a network of distances between the atoms in the protein molecules that make up a fibril (Fig. 2). Extensive calculations enabled the atomic structure of the fibril to be reconstructed from these measurements.
The main part of the beta-amyloid 1-42 peptide is shaped like a double horseshoe (Fig. 3). Pairs of identical molecules form layers, which are stacked onto each other to form a long fibril. Numerous hydrogen bonds parallel to the long axis lend the fibrils their high stability.
"The structure differs fundamentally from earlier model studies, for which barely any experimental measurement data was available." explains Prof Peter Güntert, professor of computational structural biology at Goethe University.
The publications released by the two teams, which confirm each other, have caused excitement in expert circles, as they enable a targeted, structure-based search for medicines that will attack the beta-amyloid fibrils. The researchers hope that this scourge of old age, first described 110 years ago by the Frankfurt-based physician Alois Alzheimer, will finally be defeated over the next one or two decades.
Wälti, M. A., Ravotti, F., Arai, H., Glabe, C., Wall, J., Böckmann, A., Güntert, P., Meier, B. H. & Riek, R. Atomic-resolution structure of a disease-relevant Aβ(1-42) amyloid fibril. Proceedings of the National Academy of Sciences of the United States of America, DOI 10.1073/pnas.1600749113.
Colvin, M. T., Silvers, R., Ni, Q. Z., Can, T. V., Sergeyev, I., Rosay, M., Donovan, K. J., Michael, B., Wall, J., Linse, S. & Griffin, R. G. Atomic resolution structure of monomorphic Aβ42 amyloid fibrils. Journal of the American Chemical Society, DOI 10.1021/jacs.6b05129.
Xiao, Y., Ma, B., McElheny, D., Parthasarathy, S., Long, F., Hoshi, M., Nussinov, R. & Ishii, Y. Aβ(1–42) fibril structure illuminates self-recognition and replication of amyloid in Alzheimer’s disease. Nature Structural & Molecular Biology 22, 499–505 (2015).
Images are available for download here: www.uni-frankfurt.de/62697618
Fig. 1: Electron microscope image of Alzheimer fibrils
Fig. 2: Network of distance measurements in the protein molecule
Fig. 3: Structure of the amyloid-beta 1–42 fibrils
Information: Prof. Peter Güntert, Institut of Biophysical Chemistry, Campus Riedberg, Tel.: (069)-798-29621, email@example.com.