Biological Processes Continue at Glacial Temperatures

aerial photograph of frozen body of water

Biological Strategy

Ice worm

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Image: Aaron Burden / Unsplash / Free non-commercial use

Regulate Cellular Processes

Cells are the basic building blocks of all living systems, so cellular processes dictate how physiological processes occur within those systems. Cells (whether entire unicellular organisms or parts of multicellular living systems) grow, metabolize nutrients (that is, chemically transform them), produce proteins and enzymes, replicate, and move. Cells as part of multicellular systems rarely act alone, instead having ways to signal to start and complete simple to quite complex interactions. How skin heals is a good example of the role of cellular processes. Blood cells called platelets release clotting factors to stop the bleeding; white blood cells rid the area of foreign materials and release molecules to coordinate healing; cells called fibroblasts start rebuilding using proteins called collagen; new blood vessels form; and skin cells called keratinocytes create the new surface.

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Maintain Homeostasis

When a living system is in homeostasis, it means that internal conditions are stable and relatively constant. For example, a human’s internal temperature is approximately 37 degrees Celsius (98.6 degrees Fahrenheit) unless there’s an illness. The human body maintains this temperature despite external ambient temperature. However, as with all physiological processes, maintaining homeostasis requires communication and coordination. So living systems have ways to detect changes from the norm, mechanisms to cause an adjustment, and negative feedback connections between the two. A desert lizard called the Gila monster offers a good example of maintaining homeostasis. The lizard goes from eating large meals to fasting for extended time periods. To maintain its blood sugar levels at a steady level, when food is scarce, its endocrine system releases a hormone that raises its blood sugar levels.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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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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Physiological processes in ice worms allow them to survive and function in glacial ice thanks to an increase in adenylate nucleotides and other metabolic adaptations.

“The ice worm, Mesenchytraeus solifugus, is among a few metazoan species that survive exclusively in glacier ice/snow. In this study, we demonstrate that ice worm adenylate levels [i.e. adenosine 5′-triphosphate (ATP), ADP and AMP] are maintained at levels well above their mesophilic counterparts, and that their response to temperature change is distinctly opposite, namely, ice worms increase energy levels as temperatures fall. Initially, this response is characterized by a sharp spike in [ATP] and the adenylate energy charge (even at sub-zero temperatures), which is followed by corresponding increases in [ADP] and [AMP] within a few days. These results suggest that ice worms have evolved a compensatory mechanism by which gains in adenylate nucleotides off-set, at least in part, the inherent lethargy and death usually associated with cold temperature.

“…Ice worms are distinguished from freeze-tolerant and freeze-avoiding invertebrates—including several annelid species inhabiting arctic regions (e.g. [Somme and Birkemoe, 1997 and Pedersen and Holmstrup, 2003])—by their ability to maintain all biological processes at 0 °C. Freeze-tolerant/avoiding invertebrates are capable of surviving temperatures well below the lower viable limit of ice worms (i.e. ice worms have been supercooled to ≈−6.8 °C but are killed by freezing; [Edwards, 1986]), but the former requires several months of temperate climate each year to complete their life cycle. Cold-hardiness in these organisms is achieved by a variety of mechanisms including dehydration and sugar accumulation ( Holmstrup and Sjursen, 2001 and Holmstrup et al., 2002]). While the overwintering behavior of ice worms remains unknown, it has been proposed that they burrow beneath the insulating snowfall of temperate glaciers where temperatures remain near 0 °C ( [Tyen, 1970 and Goodman, 1971]).” (Napolitano et al. 2004:227-228)

Last Updated August 28, 2018

References

Journal article

The ice worm, Mesenchytraeus solifugus, elevates adenylate levels at low physiological temperature

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology | 20/11/2003 | Michael J. Napolitano, Robert G. Nagele, Daniel H. Shain

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Reference

Journal article

Cold-adapted tubulins in the glacier ice worm, Mesenchytraeus solifugus

Gene | 31/07/2008 | Lawrence J. Tartaglia, Daniel H. Shain

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