Sleep with Open Eyes in Two Species of Deer, the Indian Sambar (Rusa unicolor) and Sika Deer (Cervus nippon).

The relationship between postures, sleep stages and eye state was established in two species of deer, the Indian sambar (Rusa unicolor) and sika deer (Cervus nippon), based on video recording. In both species, the state of rest or behavioral sleep was recorded in the sternal position, holding the head above the ground, and in the lateral position, with the head resting on the croup or on the ground. Rest accounted for at least 80% of the time in these positions. Based on behavior criteria a substantial portion of rest represented slow-wave sleep. Episodes of rapid eye movements (REM sleep) were recorded in the lateral position. They did not exceed 2 min. When the deer were in the sternal posture, they kept their eyes open most of the time: in average 96% of the time in sambars and 82% in sika deer. Episodes of the open eye in this posture lasted up to 8.4 min in sambars and up to 3.3 min in sika deer. In the lateral position, such episodes were 4 and 1.5 times shorter. Sleeping with open eyes in ungulates may be an important mechanism of maintaining vigilance.

Evaluation of an Instrumental Method of Classification of Beluga (Delphinapterus leucas) Behaviors Based on the Parameters of Acceleration.

A noninvasive instrumental method of classification the behavior of the beluga whale (Delphinapterus leucas) based on the parameters of movement was evaluated. Motor activity was characterized by the mean and standard deviation of the beluga tail fluke acceleration. It was found that, using the "decision tree" algorithm, at least two types of beluga behaviors can be distinguished: resting at the surface and active swimming in the pool. The determination accuracy (depending on the parameter) was, on average, 81-97% for resting at the surface and 54-99% for active swimming behaviors. Differences between the accuracy of classification of resting at the surface based on three axis and overall body acceleration were minimal. In the future, the accuracy may be improved by using other acceleration parameters, shortening the interval of analysis, and optimizing the classification algorithms.

Characteristics of Sleep-Wakefulness Cycle and Circadian Activity in the Lesser Mouse-Deer (Tragulus kanchil).

The pattern of sleep and circadian activity of the lesser mouse-deer (Tragulus kanchil) that is the smallest (body mass between 1.5 and 2.2 kg) representative of the basal group (Tragulidae) of even-toed ungulates which evolved 40-50 Ma were studied. In naturalistic conditions, a total of 30 days of full-day video of the animal behavior and 15 days of 24-h polysomnographic data were collected in 6 animals. The mouse-deer were active less than 20% of 24 h and were quiescent during 60-80% of the remaining time. Slow wave sleep (SWS) accounted for on average 49.7 ± 3.7% of 24 h and paradoxical (rapid eye movement, REM) sleep accounted for 1.7 ± 0.3% of 24 h. During the majority of SWS (87.0 ± 4.4%) the eyes were open. The most of SWS and REM sleep occurred during the daytime hours (9 a.m. to 4 p.m.) and in the first half of the night (8 p.m. to 2 a.m.); the animals were most active during twilight hours (4-6 a.m. and 6-7 p.m.). We suggest that the main features of sleep in the mouse-deer are largely determined by ecological factors, including environmental temperature and predation, as well as the size and physiology of the mouse-deer.

Muscle jerks during behavioral sleep in a beluga whale (Delphinapterus leucas L.).

We conducted video recording of the behavior of one captive adult male beluga (or white) whale over eight nights aiming to quantify muscle jerks and to evaluate their relationship to the sleep-waking cycle. Presumably, the whale was asleep during a significant portion of the time it spent lying on the bottom of the pool. Individual sleep episodes lasted between 20 and 492 s and on average occupied 66.7+/-2.6% of the nighttime (n=8). Muscle jerks were quantified in the last three nights, during which an average of 144+/-24 jerks were documented per night. Forty-six percent of all jerks occurred within 10 s of each other. Series of jerks lasted 2-21 s (on average 4.8+/-0.5 s, n=97) and in total occupied 0.3-0.7% of the rest time (0.2-0.5% of total nighttime). Jerks occurred more frequently at the end of rest episodes. A significant portion of rest episodes with jerks (62%) followed each other. These series of episodes with jerks alternated with periods when jerks were not recorded over 8-37 min. We conclude that some jerks meet the behavioral criteria of paradoxical [or rapid eye movement (REM)] sleep (PS). On the other hand, definitive conclusions about the presence and duration of this sleep stage in cetaceans cannot be reached without further combined electropolygraphic studies and visual observations.

A novel enzyme biosensor for steroidal glycoalkaloids detection based on pH-sensitive field effect transistors.

For the design of a biosensor sensitive to steroidal glycoalkaloids, pH-Sensitive Field Effect Transistors as transducers and immobilised butyrylcholinesterase as a biorecognition element have been used. The total potato glycoalcaloids can be measured by this biosensor in the concentration range 0.5-100 microM with detection limits of 0.5 microM for alpha-chaconine and of 2.0 microM for alpha-solanine and solanidine, respectively. The responses of the developed biosensors were reproducible with a relative standard deviation of about 1.5% and 5% for intra- and inter-sensor responses (both cases, n=10, for an alkaloid concentration of 5 microM), respectively. Moreover, due to the reversibility of the enzyme inhibition, the same sensor chip with immobilised butyrylcholinesterase can be used several times (for at least 100 measurements) after a simple washing by a buffer solution and can be stored at 4 degrees C for at least 3 months without any significant loss of the enzymatic activity.

Unihemispheric slow wave sleep and the state of the eyes in a white whale.

We recorded electroencephalogram (EEG) and simultaneously documented the state of both eyelids during sleep and wakefulness in a sub-adult male white whale over a 4-day-period. We showed that the white whale was the fifth species of Cetaceans, which exhibits unihemispheric slow wave sleep. We found that the eye contralateral to the sleeping hemisphere in this whale was usually closed (right eye, 52% of the total sleep time in the contralateral hemisphere; left eye, 40%) or in an intermediate state (31 and 46%, respectively) while the ipsilateral eye was typically open (89 and 80%). Episodes of bilateral eye closure in this whale occupied less than 2% of the observation time and were usually recorded during waking (49% of the bilateral eye closure time) or low amplitude sleep (48%) and rarely in high amplitude sleep (3%). In spite of the evident overall relationship between the sleeping hemisphere and eye state, EEG and eye position in this whale could be independent over short time periods (less than 1 min). Therefore, eye state alone may not accurately reflect sleep state in Cetaceans. Our data support the idea that unihemispheric sleep allows Cetaceans to monitor the environment.