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BP: Fachverband Biologische Physik

BP 2: DNA and Chromatin

BP 2.3: Vortrag

Montag, 25. Februar 2008, 11:00–11:15, PC 203

Genome size variation in eukaryotes: its causes and consequences — •A. G. Cherstvy — FZ Juelich, IFF, 52425 Juelich

The genome size - C value - of animals reveals about 10000 fold variation. The DNA length in fishes varies about 350, while in mammals/birds only 2-4 times. Complexity of organisms and number of genes are not related to DNA content (C value paradox). The genomes of salamanders and lungfishes are 20-40 times longer than of humans, while the gene numbers are quite close. Even some invertebrates have much longer DNA (grasshoppers and amphipods). In higher eukaryotes, only a couple of percent of DNA are actually coding for proteins. The rest, "useless", DNA is probably needed to organize DNA in chromatin/chromosome. It also determines the cell/nucleus size and speed of cellular processes. A naive expectation that evolution should remove this parasitic DNA does not work. On the contrary, the genome of lungfishes, remained unchanged over last 200-300 million years, is known to grow in some eras. But, the genome of Latimeria chalumnae - another living fossil - remained constant at about the human size. C-value can vary strongly between closely related species (some fishes, crustaceans amphipods, etc). E.g., amphipods of cold waters live longer, mature/grow slower, and produce less broods than their hot water colleagues. We will compare and contrast some extreme examples of the genome sizes known, discuss physical/biological mechanisms affecting C-value, outline the role of genome duplication and repetitive DNA sequences, study longevity vs genome size correlations for some species, and speculate about developmental consequences.