The question of whether cells are bigger in larger mammals than in smaller ones think of an elephants liver cell compared with a liver cell from a mouse is usually answered by saying that larger mammals dont typically have bigger cells, they just have more of them.
Liver cells, red blood cells and other cell types that frequently divide and replace themselves are about the same size, but more permanent, long-lived cells, such as brain and fat cells, are indeed larger in large mammals.
"Fat cells increase in size tremendously if you move from a mouse to an elephant," said James Gillooly, Ph.D., an assistant professor in the zoology department of UFs College of Liberal Arts and Sciences. "Neurons also increase in size. But red blood cells are the same size whether they are in a mouse or an elephant. The reason brain and fat cells grow bigger could be because they live longer and have important long-term functions. In these cases, the properties of the cell are linked to the whole organism. But the sizes of quickly dividing cells are independent of the organism."
Neurons are essential parts of brain networks that retain memory, the researchers said, while fat cells are storehouses of energy that are vital for an animals survival when food supplies are short. As such, they are too valuable and would require a great deal of energy to be continually used and replenished in the body.
Scientists from the Santa Fe Institute, the Los Alamos National Laboratory, the National Center for Ecological Analysis and Synthesis and the University of New Mexico also participated in the study.
"The authors are saying cell size, body size and life span all go together," said Samuel Wang, Ph.D., an associate professor of molecular biology and neuroscience at Princeton University who was not a member of the research team. "In the case of brains, this suggests a reason having little to do with information processing for why bigger brai
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Contact: John D. Pastor
jdpastor@ufl.edu
352-273-5815
University of Florida
8-Mar-2007