Mechanisms and peculiarities of dormancy in veretebrates and

Mechanisms and peculiarities of dormancy in veretebrates and invertebrates Биологический покой у позвоночных и беспозвоночных N. Abramson, V. Alekseev Zoological Institute RAS

Terms and definitions n Keilin Active life=normal metabolism (1959) Laudien 1973 Dormancy cause of the arrest in development as criterion Hypobiosis diapause dormancy (hypometabolism) Hibernation aestivation Diapause quiscience Latent life (ametabolism) Criptobiosis Anabiosis includes a complicate internal hormonal mechanism that needs in time both for beginning and finishing its work. As result diapause starts before really harsh conditions and can not be immediately broke even if favorable conditions return quiscience Induced directly by unfavorable conditions and development is resumed soon after return to favorable conditions

The first researches on the diapause were carried out at the beginning of the 20 th century on the silkworm (Bombix mori). The neologism “diapause” was subsequently extended from insects to other taxa which exhibited a similar kind of adaptation in many details, including hormone identity or level of metabolic depression; these included porifera, turbellaria, briozoa, rotifera, oligochaeta, tardigrada, crustacea and collembola.

The diapause may occur at different development stages

Hibernation in mammals Hibernation is an adaptive strategy that is used by species in several mammalian orders to conserve energy in cold or inhospitable environments. During hibernation these mammals dramatically lower their metabolic, heart, and respiratory rates as well as their body temperature in a precisely controlled manner. In species with winter hibernation the body temperature usually falls below 10° С. Minimal temperature in 3°С was recorded in arctic ground squirrel Spermophilus undulates, though in majority of this species do not fall below 5°С.

Remarkably hibernation occurs in seven different orders of mammals primates bats monotremes marsupials insectivores rodents

two hypothesis explaining the interspersed nature of the distribution of extant hibernating species through Mammalia primates bats insectivores ungulates carnivores common ancestor is a hibernator rodents lagomorphs marsupials common ancestor is not a hibernator monotremes Lineages where the ability to hibernate partially lost or completely lost Lineages where hibernation must have arisen

Expression of PDK-4 during the hibernation season. (A) Northern blot of total RNA from the hearts of active and hibernating 13 -lined ground squirrels. (B) Bar graph summarizing PDK-4 m. RNA levels in the hearts of sibling and nonsibling ground squirrels (C) Tissue distribution of PDK-4 m. RNA from a single hibernating animal sacrificed in January during hypothermic torpor (Tb 5 5°C). Tissues are as indicated above each lane

c. DNAs encoding human and ground squirrel PTLs expressed inthe yeast P. pastorisboth human and ground squirrel PTL perform remarkably well at low temperatures. At 0◦C, the enzyme from ground squirrel still maintains 48 and 33% of the maximal activity (seen at 37◦C) with tributyrin and triolein respectively. Human PTL showed 42% maximal activity at 0◦C using tributyrin and an amazing 55% maximal activity using triolein. This result shows that the low-temperature catalysis seen with a protein in hibernators is also found in humans.

Model depicting the central role of differential gene expression during hibernation. Single arrows indicate direct effects, whereas multiple arrows indicate an effect that requires multiple intermediate events

similar or close in vertebrate and invertebrates n n n Displayed independently in different sometimes very distant orders under the influence of environmental factors occur at different development stages (e. g. eggs, embryos, juveniles or adults) Suppression of metabolism (in diapause is 3 -6 times lower than in in active at the same ambient temperature) and characteristic features of development (period of preparing, gradual suppression of metabolic functions, refractory phase, , exit) The duration of refractory phase usually do not exceed 3 months, after that they could be reactivated by transfer to favorable conditions. This period coincides with the period of activity of diapause inhibiting hormone as it was shown for decapodes (Alexseev, 1998). There is significant similarity in chemical mechanism of hormonal control of resting phase in these animals гормоны,