Reading Sponges Although primitive, sponges have nearly the same basic genetic makeup as more complex animals? including the human. This is shown by a preliminary analysis of the genome of a horned pebble sponge called Amphimedon queenslandica, which has now been successfully completed by an international research team. The results not only help to understand the strange animals better, write the scientists, including researchers from the University of Göttingen. Above all, they reveal the genetic inventions and innovations that were needed to develop multicellular animals from the early unicellular organisms. In addition, they allow conclusions about what the last common ancestor of all Mehrzeller could have looked like? after all, the lineage of sponges has been one of the first to separate from the main line. Accordingly, this ancestor of animals was already more complex than previously thought. Sponges are very simply structured: they have no organs, no nerves and no muscles. Nevertheless, the study of her genome was a challenge, say the scientists around Mario Stanke. To obtain sufficiently clean DNA, for example, they had to resort to embryos and larvae because the adult animals are often heavily populated with bacteria. The acquired genetic material was then elaborately processed, so that ultimately only the areas were left that actually carry blueprints for proteins. Their structure was compared in the last step with that of other animals, including worms, fruit flies and mice.
The similarity between the sponge genome and the more complex animals was unexpectedly large, the scientists write. For example, the entire basic genetic toolbox already exists: the sponges have genes to control the cell cycle, to control cell growth and to monitor the death of cells, genes for germ cell specialization, attachment of the cells to each other and to the cells Defense and the recognition of foreign protein structures. All this suggests that the transition from single to multi-cell has required the development of mechanisms to coordinate cell division, growth, and specialization? and that even the common ancestor of the animals had these mechanisms, the researchers say.
However, the downside of this development is of particular interest to humans. Because the more complex the organism and thus its control mechanisms, the more error-prone they became. One of the consequences of this is the development of cancer, according to the researchers a "disorder of multicellular disorder" in which some cells grow uncontrollably. A better knowledge of the processes that allowed the multicellularity could therefore also provide new insights into cancer and thus new targets for its treatment, the scientists hope.
Mario Stanke and Daniel Jackson (University of Göttingen) et al .: Nature, Vol. 466, p. 720 ddp / science.de? Ilka Lehnen-Beyel advertisement