[THE EFFECT OF MOTION SICKNESS ON THE SLEEP-WAKE CYCLE IN RATS EXPOSED TO PRENATAL HYPOXIA].

This study is a continuation of our research of phenomenology and mechanisms of motion sickness (MS) and the relation of this phenomenon to features of sleep-wake cycle (SWC) changes. It presents data about the effect of MS on SWC in 30-day-old intact rats and rats exposed previously to prenatal hypoxia on days 13 and 19 of gestation. In all groups of animals MS was shown to reduce significantly the waking time and to increase the time of paradoxical sleep (PS).

[Motion sickness in lower vertebrates: studies under conditions of weightlessness and under land conditions].

The review presents literature data and results of the author's studies with the goal to find out whether lower animals are susceptible to motion sickness. In our studies, fish and amphibians were tested for 2 h and more by using a rotating device (f = 0.24Nz, a(centrifugal) = 0.

Behavior of toads, Bufo bufo, in a dynamic environment.

Susceptibility to motion sickness was tested by exposing free moving toads to rotation of a stimulator modeled after an amusement park Ferris Wheel. The stimulator provided a gentle stimulation of frequency 0.25 Hz and centrifugal acceleration 0.

[Effect of swinging on EEG of rats of juvenile age in the wakefulness state].

Simultaneous recording of the EEG activity of superficial cortical and deep (caudate nucleus, dorsal hippocampus, anterior hypothalamus) brain parts has been performed for the first time after a 2-h swinging of frequency of 0.2 Hz in Wistar rats of juvenile age. Swinging was produced on a 4-bar parallel swing.

[Behavior of trout fry Salmo gairdneri during swinging].

Ten experimental and 10 control experiments on a parallel swing and 4 experiments on a rotating stand were carried out on the fries of the trout Salmo gairdneri, strain Rofor. Depending on changes of motor activity the fish could be divided into three groups: the "freezing" fish, in which the mean swimming rate dropped sharply with the beginning of swinging; (2) the shuttle-swimming fish, in which the mean swimming rate in the process of swinging practically did not change, but which with beginning of swinging started the from-wall-towall swimming in the horizontal plane by changing direction of the movement with a frequency close to the swinging frequency; (3) the "restless" fish, in which significant fluctuations of the meanswimming rate were observed. A decrease of the motor activity in the first group fish seems to be a protective reaction.

Fish otolith asymmetry: morphometry and modeling.

Mathematical modeling suggests that relatively large values of otolith mass asymmetry in fishes can alter acoustic functionality and may be responsible for abnormal fish behavior when subjected to weightlessness during parabolic or space flight [D.V. Lychakov, Y.

Fish otolith mass asymmetry: morphometry and influence on acoustic functionality.

The role of the fish otolith mass asymmetry in acoustic functionality is studied. The saccular, lagenar and utricular otoliths are weighted in two species of the Black Sea rays, 15 species of the Black Sea teleost fish and guppy fish. The dimensionless otolith mass asymmetry chi is calculated as ratio of the difference between masses of the right and left paired otoliths to average otolith mass.

Otolith regularities.

The masses and the area sizes of the otoliths for the utriculus, sacculus and lagena of 15 species of the Black Sea fish are analyzed. Morphometrical otolith regularities are derived and their functional and ecomorphological explanations are suggested. The otolith regularities are summarized in four otolith rules: (1) the masses of the otoliths gradually increase with the fish growth.

Otoconia biogenesis, phylogeny, composition and functional attributes.

This work consolidates data about these interesting organic crystals of vertebrate inner ears. It addresses 5 aspects of inner ear otoliths not completely understood to date: 1) embryological data that explains the formation of the crystals, 2) the significance of the organic and the inorganic phase of the otolith and the changing patterns of otoconia formation along the evolutionary tree, 3) otoliths contribution for detecting linear acceleration, 4) the effect that altered gravity and aminoglycosides have on the development and adult shape of the crystals, and the evolutionary significance of a changing shape of the crystals from primitive forms (lamprey) to high vertebrate birds and mammals is discussed, 5) functional attributes of the otolithic organs and morphological modifications of the otoliths by physical and chemical insults are presented with an extensive discussion of the most relevant literature published and available to us.

[The content of electrolytes (Na, K, Ca, Mg) in vertebrate otoliths and otoconia].

Na, K, Ca and Mg concentrations have been determined in the otoliths and otoconia of the lamprey, skate, guppy and hen. Lamprey otoliths sharply differ from the otoliths and otoconia of other animals with respect to their K and Ca content. In all the animals investigated excluding lamprey, only traces of K were found.

[The vestibular apparatus of quail embryos in an experiment on the Kosmos-1129 biosatellite].

The light microscope was used to study serial sections of labyrinths of quail embryos incubated and reared during 12 d orbiting of Cosmos 1129. On recovery the embryos were aged 9, 11.5 and 12 days.

[The turning reflex, static endurance and structure of the vestibular apparatus receptors in rats exposed to whole-body low-frequency vibration].

Wistar rats were for 2 weeks exposed to vibrations of 18 Hz (acceleration of 2.3 G applied for 5.8 hrs a day for as long as 58 hrs) and 30 Hz (acceleration of 9.

[Study of the structure of receptor organs of the vestibular apparatus of rats after space flight on "Kosmos-1667"].

The receptor organs of the vestibular apparatus of rats flown for 7 days on Cosmos-1667 were examined. Serial sections were examined by light microscopy, some utriculus sections by electron microscopy, and otolith membranes by scanning electron microscopy. The fixation method used revealed a distinct structural heterogeneity of the receptor epithelium.

[Changes in the otolithic apparatus of rats and fish after long-term rotation with increased acceleration].

Otolith membranes of the utriculus and sacculus of rats exposed to 2 g during a month showed a typical size-related distribution of otoconia, which had optic activity. The length (L) and diameter (D) of utricular otoconia were linearly correlated as follows: D = 0.4 + + 0.