The size of the Hydra attenuata (vulgaris?) genome was measured by Charles David and Richard Campbell in 1972 (J. Cell Science 11, 557-568) using microspectrophotometry of Feulgen-stained nuclei. The diploid nucleus contained 3.5 picograms of DNA. This gives a haploid genome size of 1.6 x 10exp9 base pairs. This compares to the haploid genome sizes of other organisms as follows:
The base composition of the Hydra genome is very A+T-rich. The base composition was measured some years ago by Joseph Gall (then at Yale University) using buoyant density centrifugation and determined to be 71.4% A+T. This result has never been published, so it should be cited as a personal communication.
As expected from the A+T-rich base composition of the Hydra genome, the codon usage in Hydra genes is very biased in favor of codons with an A or T at the third position. This has been seen for every gene that has been cloned from Hydra. A codon usage table for hydra genes was published in January 1993. The reference is:
Galliot, B. and Schummer, M. (1993). 'Guessmer' screening strategy applied to species with AT-rich coding sequences. Trends in Genetics 9, 3-4.
For comparison to the codon usage in hydra you can examine the codon usage in a variety of other organisms by clicking here.
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