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Dormancy is a period in an organism’s life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions.

Organisms can synchronize entry to a dormant phase with their environment through predictive or consequential means. Predictive dormancy occurs when an organism enters a dormant phase before the onset of adverse conditions.

For example, photoperiod and decreasing temperature are used by many plants to predict the onset of winter.

Consequential dormancy occurs when organisms enter a dormant phase after adverse conditions have arisen.

This is commonly found in areas with an unpredictable climate. Very sudden changes in conditions can lead to a high mortality rate among animals relying on consequential dormancy. However, using this dormancy can be advantageous. Organisms remain active longer and are therefore able to make greater use of available resources.

Aestivation

Aestivation, also spelled estivation, is an example of consequential dormancy in response to very hot or dry conditions. It is common in invertebrates such as the garden snail and worm. It also occurs in other animals such as lungfish, salamanders, desert tortoises, and crocodiles.

Diapause

Diapause is a predictive strategy that is predetermined by an animal’s genotype. Diapause is common in insects. It allows them to suspend development between autumn and spring. It also occurs in mammals like the roe deer (Capreolus capreolus, the only ungulate with embryonic diapause[citation needed]). In this case, the embryo’s attachment to the uterine lining is delayed. This delay ensures that offspring are born in spring. This timing allows for conditions to be most favorable.

Brumation

Brumation is an example of dormancy in reptiles that is akin to hibernation. It differs from hibernation in the metabolic processes involved.

Reptiles generally start brumation in late autumn (more specific times depend on the species). They often wake up to drink water and return to “sleep”. They can go for months without food. Reptiles eat more than usual before the brumation time but eat less or refuse food as the temperature drops. Nonetheless, they do need to drink water.

The brumation period varies from one to eight months. This depends on the air temperature. The size, age, and health of the reptile also influence the duration. In the first year of life, many small reptiles do not fully brumate. Instead, they slow down and eat less often. Brumation is triggered by lack of heat and the decrease in the hours of daylight in winter, similar to hibernation.

Hibernation

Hibernation is a mechanism used by many mammals to reduce energy expenditure and survive food shortage over the winter. Hibernation is predictive or consequential.

An animal prepares for hibernation. It builds up a thick layer of body fat during late summer and autumn. This fat will give it with energy during the dormant period. During hibernation, the animal undergoes many physiological changes. These changes include a decreased heart rate by as much as 95%. Additionally, the animal experiences a decreased body temperature.

Additionally to shivering, some hibernating animals also produce body heat by non-shivering thermogenesis to avoid freezing. Non-shivering thermogenesis is a regulated process. In this process, the proton gradient generated by electron transport in mitochondria is used to produce heat. This occurs instead of producing ATP in brown adipose tissue.

Animals that hibernate include bats, ground squirrels, and other rodents, mouse lemurs, the European hedgehog, some insectivores, monotremes, and marsupials. Although hibernation is almost exclusively seen in mammals, some birds, such as the common poorwill, may hibernate.

Brumation does not always happen without certain dangers, and many wild and pet box turtles die as a result. Although winter can be a perilous time for box turtles, preparing the turtle and providing the proper type of hibernaculum will permit pet turtles to overwinter safely

Around October, turtles kept in outdoor pens will begin to have reduced appetites. Some turtles housed indoors may also begin to refuse food. They respond to subtle changes in their environment. They attempt to brumate.

It is dangerous to let turtles become dormant at room temperatures. Increase the amount of time the full-spectrum lighting is kept on to 14 hours a day.

Make sure the humidity in the indoor habitat remains high and keep the nighttime temperature above 75 degrees Fahrenheit. These changes mimic summer-like conditions and will usually keep your indoor turtle active all winter.

It is not necessary to brumate pet box turtles. Very young or newly acquired turtles should not be brumated. Instead, they should be kept in indoor habitats during the winter.

It is not necessary to brumate pet turtles. Very young or newly acquired turtles should not be brumated. Instead, they should be kept in indoor habitats during the winter.

The climate, predators, or unsuitable soils make your area unsafe for brumation. In such cases, do not allow them to brumate in the ground. Instead, use artificial hibernacula or keep them active all winter in indoor habitats. Only healthy box turtles that have eaten well all summer should be hibernated.

Turtles should not be hibernated if they have recently recovered from illness. They should also avoid hibernation if they currently have swollen or closed eyes. Discharge from the nares or mouth is another reason to avoid hibernation. Runny stools are also concerning. Swellings on the head, being underweight, open wounds, or prolapsed organs are also conditions that prevent hibernation. When any of these symptoms exist, have them examined by a veterinarian.

Brumation Checklist

• Supplement the diet in late summer with vitamin A-rich food.
• Get a fecal test to look for parasites and a veterinary exam a month before hibernation.
• Prepare the brumation pit, refrigerator, or brumation box early.
• Stop feeding the turtle at least two to three weeks before brumation begins. This will ensure the turtle has an empty stomach. It also ensures the intestines are empty.
• Soak the turtle daily for several weeks before brumation to make sure they are properly hydrated.

Preparing for Brumation

Offer more vegetables rich in vitamin A during the last month of warm weather. These include sweet potatoes, carrots, pumpkin, and winter squashes. You can add a few drops of cod liver oil to food once a week. Alternatively, add a soluble or liquid vitamin A-rich supplement to the water once a week. Do this for a month before they stop eating.

Be careful not to overuse vitamin A supplements because hypervitaminosis A can occur.

Overdosing on vitamin A can cause skin redness and peeling, as well as liver disease. Daily soakings a few weeks before actual hibernation will facilitate the clearing of the turtle’s intestine of wastes.

Plant Dormancy

In plant physiology, dormancy is a period of arrested plant growth. Many plant species exhibit this survival strategy. It enables them to survive in climates where part of the year is unsuitable for growth. These periods include winter or dry seasons.

Many plant species that exhibit dormancy have a biological clock. This clock tells them when to slow down activity. It also prepares their soft tissues for freezing temperatures or water shortage.

On the other hand, dormancy can be triggered after a normal growing season. It can occur due to decreasing temperatures. Shortened day length and/or a reduction in rainfall can also trigger it.

Chemical treatment on dormant plants has been proven to be an effective method to break dormancy. This is particularly true for woody plants such as grapes, berries, apples, peaches, and kiwis.

Specifically, hydrogen cyanamide stimulates cell division and growth in dormant plants. It causes bud break when the plant is on the edge of breaking dormancy.

Slight injury to cells play a role in the mechanism of action. The injury is thought to result in increased permeability of cellular membranes.

The injury is associated with the inhibition of catalase, which in turn stimulates the pentose phosphate cycle. Hydrogen cyanamide interacts with the cytokinin metabolic cycle, which results in triggering a new growth cycle.

When a mature and viable seed under a favorable condition fails to germinate, it is said to be dormant. Seed dormancy is also known as embryo dormancy or internal dormancy. It is caused by the embryo’s endogenous characteristics that prevent germination.

Dormancy should not be confused with seed coat dormancy, external dormancy, or hardseededness. These conditions are caused by a hard seed covering or seed coat. This barrier prevents water and oxygen from reaching and activating the embryo.

It is a physical barrier to germination, not a true form of dormancy. Typically, temperate woody perennial plants require chilling temperatures to overcome winter dormancy (rest). The effect of chilling temperatures depends on species and growth stage (Fuchigami et al. 1987).

In some species, rest can be broken within hours at any stage of dormancy. This can be achieved with chemicals, heat, or freezing temperatures. The effective dosages act as sublethal stress. This stress results in the stimulation of ethylene production and increased cell membrane permeability.

Dormancy is a general term. It applies to any instance. This occurs when a tissue, which is predisposed to elongate or grow, does not do so (Nienstaedt 1966).

Quiescence is dormancy imposed by the external environment. Correlated inhibition is a physiological dormancy. It is maintained by agents or conditions originating within the plant. These do not originate within the dormant tissue itself.

Rest (winter dormancy) is a physiological dormancy maintained by agents or conditions within the organ itself.

However, physiological subdivisions of dormancy do not coincide with the morphological dormancy found in white spruce (Picea glauca) and other conifers (Owens et al. 1977).

Physiological dormancy often includes early stages of bud-scale initiation before measurable shoot elongation or before flushing. It may also include late leaf initiation after shoot elongation has been completed. In either of those cases, buds that are dormant are nevertheless very active morphologically and physiologically.

Dormancy of various kinds is expressed in white spruce (Romberger 1963). White spruce, like many woody plants in temperate and cooler regions, needs exposure to low temperatures for weeks. This exposure is required before it can resume normal growth and development.

This “chilling requirement” for white spruce is satisfied by uninterrupted exposure to temperatures below 7°C. This exposure lasts for 4 to 8 weeks. The duration depends on physiological condition (Nienstaedt 1966, 1967).

Tree species that have well-developed dormancy needs can be tricked to some degree, but not completely. For example, if a Japanese Maple (Acer palmatum) receives extra daylight, it experiences an “eternal summer.” The tree grows continuously. This can last for as long as two years.

Eventually, nevertheless, a temperate-climate plant automatically goes dormant, no matter what environmental conditions it experiences. Deciduous plants lose their leaves; evergreens curtail all new growth. Going through an “eternal summer” and the resultant automatic dormancy is stressful to the plant and usually fatal.

The fatality rate increases to 100% if the plant does not receive the necessary cold period. This cold period is required to break the dormancy. Most plants need a certain number of hours of “chilling” at temperatures between about 0°F and 50°F. This chilling is necessary to break dormancy.

Short photoperiods induce dormancy and permit the formation of needle primordia. Primordia formation requires 8 to 10 weeks and must be followed by 6 weeks of chilling at 2 °C.

Bud break occurs promptly if seedlings are then exposed to 16-hour photoperiods at the 25°C/20°C temperature regime. The free growth mode is a juvenile characteristic. It is lost after 5 years or so. This growth mode ceases in seedlings experiencing environmental stress.

Many bacteria can survive adverse conditions such as temperature, desiccation, and antibiotics. They achieve this by forming endospores, cysts, conidia, or entering states of reduced metabolic activity. These states lack specialized cellular structures.[14] Up to 80% of the bacteria in samples from the wild appear to be metabolically inactive. Many of which can be resuscitated. Such dormancy is responsible for the high diversity levels of most natural ecosystems.

Recent research has characterized the bacterial cytoplasm as a glass forming fluid approaching the liquid-glass transition,

Large cytoplasmic components need metabolic activity to help them. This activity fluidizes the surrounding cytoplasm. It allows these components to move through a viscous, glass-like cytoplasm.

During dormancy, when such metabolic activities are put on hold, the cytoplasm behaves like a solid glass, freezing subcellular structures in place and protecting them, while allowing small molecules like metabolites to move freely through the cell, which may be helpful in cells transitioning out of dormancy

Dormancy, in its rigid definition, doesn’t apply to viruses, as they are not metabolically active. Still, some viruses, like poxviruses and picornaviruses, can become latent after entering the host. They stay inactive for long periods. In some cases, they can stay inactive indefinitely until they are externally activated.

Herpesviruses, for example, can become latent after infecting the host. After years, they can activate again if the host is under stress or exposed to ultraviolet radiation.

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