DNA Self-repairs After Exposure to Ionizing Radiation

Biological Strategy

Rotifers

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Regulate Reproduction or Growth

Reproduction and growth are two physiological processes that occur in all living systems. There are situations when conditions are right for both, and other situations when continuing either harms the living system because both have a very high energy cost. Reproduction and growth are unique in that both can stop until conditions improve, although stopping either for an extended time can cause problems. An example of regulating reproduction is a process called delayed implantation or embryonic diapause found in some mammals, such as otters. An otter’s embryos sometimes temporarily cease developing and won’t develop further until the female senses that conditions are suitable.

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Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Animals

Kingdom Animalia (“having breath or soul”): Mammals, reptiles, sponges, corals, insects, birds

This kingdom captures a staggering variety of life—from the smallest coral polyp to the largest elephant. Although animal body shapes and life histories vary, there are a few defining characteristics. Animals are heterotrophs, meaning they gain energy from eating other organisms, and have developed from single-celled ancestors to highly diversified and coordinated multicellular forms. Unlike plant and fungi cells that have rigid cell walls, animal cells are bound by more flexible combinations of proteins. Most animals have cells organized into tissues and are able to move within their environment.

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Bodies survive extreme exposure to ionization radiation in certain species of Rotifers of class Bdelloidea by repairing DNA.

Rotifers of class Bdelloidea are small invertebrates that inhabit temporary aqueous environments (i.e., freshwater pools), mosses, and lichens. When these environments dry up, these tiny animals are subject to drought that would likely kill most other species. However, two species of the above class, Adineta vaga and Philodina roseola are not only able to survive such conditions, but are able to reproduce (and thus, thrive) afterwards. Scientists, Gladyshev and Meselson, tested their survival by exposing the species to ionization radiation (IR) and made a comparison of these species to a species of bacteria that avoids desiccation. These researchers believe that survival techniques such as IR resistances are the result of evolutionary divergence from other species thousands of years ago to avoid desiccation; they hypothesize that the animals DNA undergo repair from breakage after the extreme conditions of the environment are removed. Understanding how these animals are capable of being exposed to such extreme conditions and then bouncing back to reproduce may provide clues as to how humans can repair their own DNA after damage or perhaps provide humans with a better way to preserve food that undergoes extreme conditions of transportation.