And that means that studying hydra could help scientists unravel the mystery of why most animals do age. But the findings fly in the face of old models that assumed that all animals must decline with age, Martinez said. In the wild, disease, predators and water contamination kill off hydras before they can achieve immortality. "I do believe that an individual hydra can live forever under the right circumstances," Martinez said. The other 20 percent fluctuated up and down, likely because of laboratory conditions. (The "oldest" animals studied were clones of hydras that had been around for 41 years - though individuals were only studied for eight years, some were biologically older because they were genetic clones.) Likewise, fertility remained constant for 80 percent of the individual hydras over time. Death rates held constant at one per 167 hydras per year, no matter their age. Over eight years, the researchers found no evidence of senescence in their coddled hydra. The researchers wanted to give the animals ideal conditions, which meant giving each an individual dish, with the water changed thrice weekly, plus meals of fresh brine shrimp. The new research involved creating little islands of paradise for 2,256 hydras. In that 1998 study, researchers couldn't pin down whether or not hydra fertility declined with age. To detect aging, researchers look at senescence, which is defined as an increased rate of death and a decline in fertility with greater age. In 1998, Martinez and his colleagues published a study describing how they found no signs of aging in mature hydras over four years. Hydra, by contrast, constantly renew their bodies with fresh cells. In humans, such "totipotent" cells are present only in the first few days of embryonic development. These cells are capable of continuous division and differentiation into any cell type in the body. Most of their body cells are stem cells, Martinez said. Hydra are known for their regenerative capabilities. They grow only about 0.4 inches (10 millimeters) long and eat even tinier aquatic animals. Hydra are a group of invertebrates that look like tiny tubes with tentacles protruding off one end.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |