Cells from the smallest to the largest of mammals often seem to be "one size fits all." Now a closer look reveals that whether a cell lives in an elephant, mouse or something in between can make a big difference in its life.
Researchers from the University of Florida Genetics Institute, Harvard Medical School and other institutions developed mathematical models that they used to examine 18 cell types from mammals ranging from mice to elephants. They found two basic categories cells that stay the same size but have drastically different energy needs that depend on the size of the mammal, or cells that grow larger in larger mammals and use energy at the same rate, no matter the mammals size.
The discovery, published online this month in the Proceedings of the National Academy of Sciences, begins to answer questions about how the size of an organism helps determine the life span of its cells, a finding that could help cell biologists and physiologists understand cell and organ function and their relation to disease.
"Although cells are basic building blocks, their metabolic rates depend on where they find themselves living," said Van M. Savage, Ph.D., the lead author of the research and an instructor in the department of systems biology at Harvard Medical School. "Conceptually this is important because huge amounts of research on human diseases are done on single cells or cultured cells that come from other animals and little is done to place these findings within the context of the size or other whole-body properties of the animals."
Generally, the size of a species of mammal sets the pace of its life, Savage said. The life spans of a mouse and elephant can differ by more than 70 years, and it takes a mouse 20 days of gestation before delivering a baby compared with more than 600 days for an elephant. The larger the animal, the slower its cellular metabolic rate the speed at which it burns oxygen and life processes.