Pancreatic cell size linked to mammalian lifespan, finds zoo animal analysis

June 18, 2018, Cell Press

More than two thousand years ago, Greek philosopher Aristotle observed that larger animals tend to live longer than smaller ones. On June 18 in the journal Developmental Cell, scientists report that it's cell size, not body size, that intrinsically correlates with and perhaps affects lifespan. By examining the pancreases of 24 mammalian species—including shrews, humans, and tigers—researchers in Israel, Canada, and Germany found that animals with larger pancreatic cells tend to age faster, while smaller cells seem to go hand in hand with longer lifespans.

"That there was a correlation between two things that are so remote was shockingly beautiful and unexpected," says senior author Yuval Dor, who studies developmental biology at the Institute for Medical Research Israel-Canada and The Hebrew University-Hadassah Medical School in Jerusalem.

"This study has exposed a trend that seems to transcend all animal life," says co-author Ran Kafri, a computational biologist at the University of Toronto and the Hospital for Sick Children in Canada. "It demonstrates that there's a property that can be measured on a single cell that predicts the lifespan of a whole animal."

Scientists had thought that after birth, most mammals' organs, including the pancreas, grow by cell proliferation. However, Dor, Kafri, and colleagues made a serendipitous observation; they needed a higher magnification to look at pancreatic cells of new-born mice through a microscope than they did to look at those of adults, suggesting that each cell's volume was substantially increasing from infant to adult life.

Repeated measurements showed that the growth of individual exocrine pancreatic cells, known as acinar cells, is responsible for much of the overall organ growth after birth. "This was surprising because the assumption was that postnatally, the pancreas grows by increasing the number of cells just like most organs that we think about," says Dor.

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Wood toxin could harm zoo animals

Date: May 20, 2016

Source: University of Florida Institute of Food and Agricultural Sciences

When those cute animals gnaw on wood enclosures at a zoo, they may be risking their health by ingesting toxic levels of arsenic, so zoo managers need to pay attention to the potential risk of the wood on zoo animals, a new University of Florida Institute of Food and Agricultural Sciences study shows.

The wood in question is treated with chromated copper arsenate (CCA), which can be toxic.

After visiting a zoo with her family, Julia Gress, a former post-doctoral researcher in the UF/IFAS soil and water sciences department, recognized that animals living in enclosures made from CCA-treated wood might face health risks.

Gress wanted to assess the impact of CCA-treated wood on arsenic exposures in zoo animals. She measured arsenic concentrations in soil from inside enclosures and on wipe samples of CCA-treated wood. Samples were taken from inside 17 wood enclosures, and also included crocodilian eggs, bird feathers, marmoset hair and porcupine quills.

Researchers found arsenic levels in soil that were higher than the U.S. Environmental Protection Agency's risk-based level for birds and mammals. As well, arsenic levels in some animal tissues were also higher than those in other studies. Those findings should encourage zoo managers to limit animal exposure to arsenic found on the wood surface and in nearby soil, Gress said.

"Zoos care about the animals, which are often worth a lot of money," said Gress, who conducted her search under the guidance of UF/IFAS soil and water sciences professor Lena Ma. Gress now works at the California Department of Toxic Substances Control in the Safer Consumer Products program.

CCA-treated wood is used in many structures. CCA preserves wood and extends its life by 20 to 40 years, but it contains large amounts of arsenic. CCA was withdrawn from use in most residential applications in 2004 because of health concerns over arsenic. Still, CCA-treated poles, fencing and plywood are still commonly used in areas where animals are housed, including barns, feedlots and zoos, according to the study.

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Birth Control at the Zoo: Vets Meet the Elusive Goal of Hippo Castration

Dec. 20, 2013 — One method for controlling zoo animal populations is male castration. For hippopotami, however, this is notoriously difficult, as the pertinent male reproductive anatomy proves singularly elusive. Veterinarians from the Research Institute of Wildlife Ecology of the University of Veterinary Medicine, Vienna, and colleagues, have demonstrated a successful method for castrating male hippos.

Their results are published in the journal Theriogenology.

Common hippopotami (Hippopotamus amphibius) are vulnerable to extinction in the wild, but reproduce extremely well under captive breeding conditions. 

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