You Are What You Eat

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Science  25 Aug 2006:
Vol. 313, Issue 5790, pp. 1020
DOI: 10.1126/science.313.5790.1020c

Plant biomass contains a lower percentage of N than animal biomass because plants have relatively more carbohydrate and less protein. To look more deeply at elemental aspects, Elser et al. compared the proteomes of nine plants and nine animals. The proteomes of plants were found to have a lower N content than those of animals; on average, animals had 7% more N atoms per amino acid. Furthermore, N content is related to overall gene expression level in such a way that, on average, plants have a lower N content in genes that are more highly expressed, whereas no discernible correlation with expression existed in the animal proteomes. These findings may reflect an eco-physiological selection away from the use of N-rich amino acids in plants, perhaps as a result of a greater sensitivity to limiting N supplies. — LMZ

Mol. Biol. Evol. 23, 10.1093/molbev/msl068 (2006).

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