Sleep and wakefulness in Greenland seal pups

ECoG of both hemispheres, EOG, neck EMG and EKG were recorded in 2 white (age 10 days) and 2 gray pups (age 1 month) of harp seal. The active wakefulness occupied 23.4 +/- 3.8% of total recording time, the relaxed wakefulness--32.6 +/- 3.6%, drowsiness--4.8 +/- 1.1%, slow wave sleep--31.5 +/- 3.0%, paradoxical sleep--7.7 +/- 0.8%. The sleep cycle averaged 18.2 +/- 1.4 min. Interhemispheric asymmetry of the ECoG was not seen in all 4 pups. The respiration was fast and regular in the relaxed wakefulness, then long respiration pauses were alternated with episodes of hyperventilation during slow wave sleep and there was rare and irregular respiration in the paradoxical sleep. The heart rate was lowest during the paradoxical sleep. It is suggested that this pattern of sleep, allowing seals to delay their breathing during sleep for a long time may be considered as an adaptation to existence in freezing seas.     

Relationship between sleep and eye state in Cetaceans and Pinnipeds

We recorded EEG from both hemispheres and documented the state of the two eyes in two species of Cetaceans (one beluga and one bottlenose dolphin) and one species of Pinnipeds (two northern fur seals). In the dolphin and beluga we found that episodes of unihemispheric slow wave sleep (USWS) were associated with asymmetry in eye state. During USWS and asymmetrical SWS the eye contralateral to the sleeping hemisphere was mostly closed or in an intermediate state while the eye contralateral to the waking hemisphere was more often open or in an intermediate state. Bilateral eye opening indicated waking in about 80% cases and unilateral eye closure indicated USWS with an accuracy of about 75%. Bilateral eye closure was rare (< 2% of the observation time) and was not necessarily associated with high amplitude SWS. In fur seals, episodes of one eye briefly opening usually occurred in the beginning of sleep episodes and lasted several minutes. Those episodes were frequently associated with lower amplitude EEG slow waves in the contralateral brain hemisphere. During most of their sleep on land, fur seals had both eyes tightly closed. No EEG asymmetry was recorded at this time. Although eye state and EEG stage are correlated in the bottlenose dolphin, beluga and fur seals, short episodes of EEG synchrony (less then 1 min) occur contralateral to an open eye and waking (a more activated EEG) activity can be present contralateral to a closed eye. The available data suggest that two functions of USWS/EEG asymmetry during SWS in Cetaceans and fur seals are multisensory control of the environment and maintenance of motion and postures of sleep. The adaptive advantages of USWS throughout the evolution of Cetaceans and Pinnipeds from terrestrial mammals to present forms could include 1) the avoidance of predators and maintenance of contact with other animals of the same species; 2) continuance of regular breathing; 3) and effective thermoregulation in the water environment.     

Features of sleep in the water by the northern fur seal Callorhinus ursinus

The peculiarities of sleep in water and on land were investigated in four adult Northern fur seals (Callorhinus ursinus) of both sexes. The electrocorticogram of both hemispheres, the neck electromyogram, the electrooculogram and electrocardiogram were recorded with implanted electrodes. The interhemispheric asymmetry of EEG during slow wave sleep was observed in all the animals sleeping in water and on land. The relative amount of interhemispheric slow wave asymmetry was higher during the sleep in water comparing to that on land. The fur seals maintain their special sleep posture on the water surface by moving only one of their front flippers. The asymmetric EEG in fur seals sleeping in the water may be attributed to the asymmetric motor activity of their flippers.     

Sleep pattern in the starling (Sturnus vulgaris)

Electrographic and behavioural observations were conducted on two male and two female captive starlings (Sturnus vulgaris) under natural illumination conditions during autumn. Polygraphically sleep and wakefulness of starling were similar to those of other birds. Starling's total sleep (TS) and slow wave sleep (SWS) lasted 39.0 +/- 1.4% and 38.3 +/- 1.7% of the 24-h period respectively. Paradoxical sleep (PS) was 1.8 +/- 0.2% of the total sleep time. The mean durations individual of TS, SWS and PS episodes were 6.8 +/- 0.2 min, 5.0 +/- 1.0 min and 18 +/- 3 s respectively. The daily percentage of SWS was correlated with the mean episode duration while that of PS was correlated with the number of episodes rather than with the mean episode duration. Starling females spent in sleep a greater percentage of the 24-h period than males.     

Sleep and wakefulness in the green iguanid lizard (Iguana iguana)

The reptile Iguana iguana exhibits four states of vigilance: active wakefulness (AW), quiet wakefulness (QW), quiet sleep (QS) and active sleep (AS). Cerebral activity decreases in amplitude and frequency when passing from wakefulness to QS. Both parameters show a slight increase during AS. Heart rate is at a maximum during AW (43.8+/-7.9 beats/min), decreases to a minimum in QS (25.3+/-3.2 beats/min) and increases in AS (36.1+/-5.7 beats/min). Tonical and phasical muscular activity is present in wakefulness, decreases or disappears in QS and reappears in AS. Single or conjugate ocular movements are observed during wakefulness, then disappear in QS and abruptly reappear in AS. Although these reptiles are polyphasic, their sleep shows a tendency to concentrate between 20:00 and 8:00 h. Quiet sleep occupies the greater percentage of the total sleep time. Active sleep episodes are of very short duration, showing an average of 21.5+/-4.9 (mean+/-SD). Compensatory increment of sleep following its total deprivation was significant only for QS. Reaction to stimuli decreased significantly when passing from wakefulness to sleep. It is suggested that the lizard I. iguana displays two sleep phases behaviorally and somatovegetatively similar to slow wave sleep and paradoxical sleep in birds and mammals.     

Evidence for the involvement of alpha-2 adrenoceptors in the sedation but not REM sleep inhibition by clonidine in the rat

Rats with implanted electrodes for recording of EEG and EMG underwent 12-h recordings during the light period starting after i.p. injections of clonidine (0.1 mg/kg) alone or in combination with different alpha-adrenoceptor antagonists. Clonidine increased the proportion of time the rats spent in the drowsy stage of wakefulness which corresponds to behavioural sedation and inhibited both deep slow wave sleep and REM sleep for 6-9 hours. The amount of active wakefulness or light slow wave sleep were unaffected by clonidine. Yohimbine (1 mg/kg) reversed the increase in drowsy wakefulness by clonidine and increased active wakefulness without affecting sleep. Phentolamine (10 mg/kg) was ineffective against clonidine. Phenoxybenzamine (20 mg/kg) accentuated the sedative effect and prolonged the REM sleep inhibiting effect of clonidine. Prazosin (3 mg/kg) prolonged both the drowsy stage inducing and deep slow wave plus REM sleep inhibiting effects of clonidine. These electrophysiological results support the view that the sedative effect of clonidine in the rat is mediated by alpha-2 adrenoceptors, whereas in this species other mechanisms, possibly another population of alpha-2 receptors, may be involved in the clonidine-induced suppression of deep slow wave sleep and REM sleep.     

Activity‐specific metabolic rates for diving,transiting, and resting at sea can be estimated from time–activity budgets in free‐ranging marine mammals

Time and energy are the two most important currencies in animal bioenergetics. How much time animals spend engaged in different activities with specific energetic costs ultimately defines their likelihood of surviving and successfully reproducing. However, it is extremely difficult to determine the energetic costs of independent activities for free‐ranging animals. In this study, we developed a new method to calculate activity‐specific metabolic rates, and applied it to female fur seals. We attached biologgers (that recorded GPS locations, depth profiles, and triaxial acceleration) to 12 northern (Callorhinus ursinus) and 13 Antarctic fur seals (Arctocephalus gazella), and used a hierarchical decision tree algorithm to determine time allocation between diving, transiting, resting, and performing slow movements at the surface (grooming, etc.). We concomitantly measured the total energy expenditure using the doubly‐labelled water method. We used a general least‐square model to establish the relationship between time–activity budgets and the total energy spent by each individual during their foraging trip to predict activity‐specific metabolic rates. Results show that both species allocated similar time to diving (~29%), transiting to and from their foraging grounds (~26–30%), and resting (~8–11%). However, Antarctic fur seals spent significantly more time grooming and moving slowly at the surface than northern fur seals (36% vs. 29%). Diving was the most expensive activity (~30 MJ/day if done non‐stop for 24 hr), followed by transiting at the surface (~21 MJ/day). Interestingly, metabolic rates were similar between species while on land or while slowly moving at the surface (~13 MJ/day). Overall, the average field metabolic rate was ~20 MJ/day (for all activities combined). The method we developed to calculate activity‐specific metabolic rates can be applied to terrestrial and marine species to determine the energetic costs of daily activities, as well as to predict the energetic consequences for animals forced to change their time allocations in response to environmental shifts.     

Ménage à trois on Macquarie Island: hybridization among three species of fur seal (Arctocephalus spp.) following historical population extinction

Human-induced changes to natural systems can cause major disturbances to fundamental ecological and population processes and result in local extinctions and secondary contacts between formerly isolated species. Extensive fur seal harvesting during the nineteenth century on Macquarie Island (subantarctic) resulted in extinction of the original population. Recolonization by three species has been slow and complex, characterized by the establishment of breeding groups of Antarctic and subantarctic fur seals (Arctocephalus gazella and Arctocephalus tropicalis) and presumed nonbreeding (itinerant) male New Zealand fur seals (Arctocephalus forsteri). One thousand and seven pups from eight annual cohorts (1992-2003) were analysed using mitochondrial control region data (RFLP) and 10 microsatellite loci to estimate species composition and hybridization. Antarctic fur seals predominated, but hybridization occurred between all three species (17-30% of all pups). Involvement of New Zealand fur seals was unexpected as females are absent and males are not observed to hold territories during the breeding season. The proportion of hybrids in the population has fallen over time, apparently owing to substantial influxes of pure Antarctic and subantarctic individuals and non-random mating. Over 50% of New Zealand hybrids and 43% of Antarctic-subantarctic hybrids were not F(1), which indicates some degree of hybrid reproductive success, and this may be underestimated: simulations showed that hybrids become virtually undetectable by the third generation of backcrossing. While human impacts seem to have driven novel hybridization in this population, the present 'time slices' analysis suggests some biological resistance to complete homogenization.     

The effect of multiple audiogenic seizures upon the sleep organization in rats

The organization of sleep during and after frequentative convulsions, consisting of 2, 3, or 5 comparatively rare seizures (following one another with a 90-minute interval) or of 3, 5 or 9 comparatively frequent seizures (following one another with a 45-minute interval) of generalized tonic-clonic character in Krushinskii-Molodkina strain rats with inherited predisposition to audiogenic convulsions, was studied. In frequentative convulsions with rare seizures, between separate seizures, passive wakefulness (75.2 +/- 4.6% time) prevailed under low (24.8 +/- 4.3%) slow-wave sleep and full absence of fast-wave sleep. In rats under frequentative convulsions with frequent seizures, in interictal period, only passive wakefulness was observed under reduction of slow-wave sleep and fast-wave sleep, i.e. total sleep deprivation. Minimal latensy of first episodes of the slow-wave sleep after frequentative convulsions was 59.9 +/- 10.8, and of fast-wave sleep: 158.2 +/- 13.4 min. First episodes of slow-wave sleep and fast-wave sleep had normal structure, though they were lesser and shorter than in control experiments. In spite of long-lasting (up to 7 hrs) absence of slow-wave sleep during seizure and prolonged (8.5 hrs) reduction of fast-wave sleep with no subsequent compensatory increase, these conditions occurred in the wakefulness-sleep cycle during 12-hour reconstruction after convulsions. The reconstruction period after frequentative convulsions was characterized by increase in general share of wakefulness and reduction of total slow-wave and fast-wave sleep as compared with control data. Paroxysmal status seems to disorganize work of the brain somnogenic structures. The function of systems responsible for slow-wave sleep are affected to a lesser extent, but disorganization of the system responsible for fast-wave sleep is more significant and associated with mechanisms of starting the phase of sleep in the first place.     

Neuromuscular and mechanical responses to inspiratory resistive loading during sleep

The purposes of this study were 1) to characterize the immediate inspiratory muscle and ventilation responses to inspiratory resistive loading during sleep in humans and 2) to determine whether upper airway caliber was compromised in the presence of a resistive load. Ventilation variables, chest wall, and upper airway inspiratory muscle electromyograms (EMG), and upper airway resistance were measured for two breaths immediately preceding and immediately following six applications of an inspiratory resistive load of 15 cmH2O.l-1 X s during wakefulness and stage 2 sleep. During wakefulness, chest wall inspiratory peak EMG activity increased 40 +/- 15% (SE), and inspiratory time increased 20 +/- 5%. Therefore, the rate of rise of chest wall EMG increased 14 +/- 10.9% (NS). Upper airway inspiratory muscle activity changed in an inconsistent fashion with application of the load. Tidal volume decreased 16 +/- 6%, and upper airway resistance increased 141 +/- 23% above pre-load levels. During sleep, there was no significant chest wall or upper airway inspiratory muscle or timing responses to loading. Tidal volume decreased 40 +/- 7% and upper airway resistance increased 188 +/- 52%, changes greater than those observed during wakefulness. We conclude that 1) the immediate inspiratory muscle and timing responses observed during inspiratory resistive loading in wakefulness were absent during sleep, 2) there was inadequate activation of upper airway inspiratory muscle activity to compensate for the increased upper airway inspiratory subatmospheric pressure present during loading, and 3) the alteration in upper airway mechanics during resistive loading was greater during sleep than wakefulness.     

Milking strategy in subantarctic fur seals Arctocephalus tropicalis breeding on Amsterdam Island: evidence from changes in milk composition.

Milk composition was investigated throughout the 10-mo pup-rearing period in subantarctic fur seals (Arctocephalus tropicalis) breeding on Amsterdam Island. The mean milk composition was 42.8% +/- 5.7% lipid, 12.1% +/- 1.5% protein, and 42.6% +/- 7.3% water. Subantarctic fur seals breeding on Amsterdam Island produced one of the richest milks ever reported in otariids (20.4 +/- 2.9 kJ/g), with lipid content contributing 85% of total gross energy. The high lipid levels measured in the milk of subantarctic fur seals breeding on Amsterdam Island is consistent (i) with the relatively long time lactating females spend at sea, due to the relatively poor local trophic conditions near the colony that necessitate that they travel long distances to reach the foraging grounds, and (ii) with the consequently short time mothers spend with their pups ashore. Milk composition changed according to the time mothers were fasting ashore: milk produced during the first 2 d spent ashore, when more than 80% of milk transfer occurred, had higher levels of lipids, proteins, and gross energy than milk produced later during the visit ashore, suggesting that the pups were fed with two types of milk during a suckling period. Throughout the year, mothers in good condition produced milk of higher lipid content than others, suggesting that individual foraging skills contribute to enhance milk quality. Milk lipid and gross energy content varied with pup age, according to quadratic relationships, increasing during the earlier stages of lactation before reaching asymptotic values when pups were 180 d old. The stage of lactation appears to be a better predictor of milk lipid content than the duration of the preceding foraging trip, suggesting that either changes in the nutritional requirements of the pup and/or seasonal changes in trophic conditions act on milk composition. These changes in milk quality may also be related to changes in maternal care; lactating subantarctic fur seals apparently reallocate their body reserves toward gestation rather than lactation at the end of the pup-rearing period.     

Serum chemistry and antibodies against pathogens in antarctic fur seals, Weddell seals, crabeater seals, and Ross seals

Information on health parameters, such as antibody prevalences and serum chemistry that can reveal exposure to pathogens, disease, and abnormal physiologic conditions, is scarce for Antarctic seal species. Serum samples from Antarctic fur seals (Arctocephalus gazella, n=88) from Bouvet?ya (2000-2001 and 2001-2002), and from Weddell seals (Leptonychotes weddellii, n=20), Ross seals (Ommatophoca rossii, n=20), and crabeater seals (Lobodon carcinophagus, n=9) from the pack-ice off Queen Maud Land, Antarctica (2001) were analyzed for enzyme activity, and concentrations of protein, metabolites, minerals, and cortisol. Adult Antarctic fur seal males had elevated levels of total protein (range 64-99 g/l) compared to adult females and pups (range 52-79 g/l). Antarctic fur seals had higher enzyme activities of creatine kinase, lactate dehydrogenase, and amylase, compared to Weddell, Ross, and crabeater seals. Antibodies against Brucella spp. were detected in Weddell seals (37%), Ross seals (5%), and crabeater seals (11%), but not in Antarctic fur seals. Antibodies against phocine herpesvirus 1 were detected in all species examined (Antarctic fur seals, 58%; Weddell seals, 100%; Ross seals, 15%; and crabeater seals, 44%). No antibodies against Trichinella spp., Toxoplasma, or phocine distemper virus (PDV) were detected (Antarctic fur seals were not tested for PDV antibodies). Antarctic seals are challenged by reduced sea ice and increasing temperatures due to climate change, and increased anthropogenic activity can introduce new pathogens to these vulnerable ecosystems and represent a threat for these animals. Our data provide a baseline for future monitoring of health parameters of these Antarctic seal species, for tracking the impact of environmental, climatic, and anthropogenic changes in Antarctica over time.     

Serum Retinol,alpha‐tocopherol,and lipids in four species of adult captive pinnipeds

The sera of adult aquarium‐held pinnipeds from four species (family Phocidae: harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus); family Otariidae: northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus)) were analyzed for vitamin A (retinol), vitamin E (α‐tocopherol), total cholesterol, triglycerides, phospholipids, and fatty acids. Each subject animal was healthy at the time of blood collection, was fasted for at least 12 hr prior to sampling, and was maintained on a constant diet and supplement regime throughout the study. Retinol values for the four species ranged from 0.16 to 0.92 μg/mL, with the lowest concentrations seen in the harbor seals and the highest in the northern fur seals. Vitamin E values ranged from 10.55 to 43.58 μg/mL, with northern fur seals showing the highest and gray seals the lowest levels. Vitamin E/lipid ratios (cholesterol, triglyceride, phospholipid, and total lipids) were also examined. A significant correlation was seen between vitamin E and total lipids (P<0.05) and phospholipid (P<0.01). Statistical analysis of the retinol, tocopherol, triglyceride, and phospholipid levels showed significant differences between phocid and otariid seals. Otariids had significantly lower tocopherol and phospholipid values (19.36 μg/mL, 4.29 mg/mL) and the phocids had significantly lower retinol and triglyceride levels (0.29 μg/mL, 124 mg/dL). There was no significant difference in serum cholesterol. Zoo Biol 22:83–96, 2003. © 2003 Wiley‐Liss, Inc.     

GENERIC NAMES OF NORTHERN AND SOUTHERN FUR SEALS (MAMMALIA: OTARIIDAE)

We have resolved a nomenclatural problem discovered during research on the northern fur seal that concerns the correct generic name for this taxon and for fur seals of the Southern Hemisphere. The unfortunate practice by some 19th-century authors to use names in their Latinized form but to date them from their first appearance as French common names led to the use of Arctocepbalus for southern fur seals when the name correctly applies to the northern fur seal, known today as Callorbinus ursinus . However, Arctocepbalus and Callorbinus are antedated by Otoes G. Fischer, 1817, which is the earliest available generic name for the fur seal of the northern Pacific. The earliest available generic name for southern fur seals is Halarctus Gill, 1866. To avoid the confusion that would result from replacing the currently used generic names with those required by strict adherence to the Principle of Priority, we have petitioned the International Commission on Zoological Nomenclature to preserve Arctocepbalus and Callorbinus for the southern and northern fur seals, respectively.     

Study of sleep in a walrus

Several behavioral and physiological adaptations have been developed in evolution of Pinnipeds allowing them to sleep both on land and in water. To date sleep has been examined in detail in eared and true seals (the families of Otariidae and Phocidae). The aim of this study was to examine sleep in another semiaquatic mammal — the walrus, which is the only extant representative of the family Odobenidae. Slow wave and paradoxical sleep (SWS and PS) in the examined walrus (2 year old female, weight 130 kg) averaged 19.4 ± 2.0 and 6.9 ± 1.1% of 24-h when on land, and 20.5 ± 0.8% of 24-h and 1.1 ± 0.6% when in water, respectively. The average duration of PS episode was 6.4 ± 0.6 min (maximum 23 min) when on land and 1.8 ± 0.1 min (maximum 3.3 min) when in water. In water, sleep occurred predominantly while the walrus submerged and lay on the bottom of the pool (89% of total sleep time). The walrus usually woke up while emerging to the surface for breathing. Most often EEG slow waves developed synchronously in both cortical hemispheres (90% of SWS time when on land and 97% when in water). Short episodes of interhemispheric EEG asymmetry usually coincided with brief opening of one eye. The pattern of sleep in the walrus was similar to the pattern of sleep in the Otariidae seals while on land (predominantly bilateral SWS, accompanied by regular breathing) and to the pattern of sleep in the Phocidae while in water (sleep during apneas both in depth and at the surface, interrupted by brief arousal when emerging for breathing).     

Effect of photostimulation on the wakefulness-sleep cycle in the common frog Rana temporaria

Effect of daily 30-min photostimulation in the 10 s light: 10 s pause (the total of 5 days) on the time structure of the wakefulness--protosleep cycle (WPC) was studied in the common frog Rana temporaria. Changes were analyzed of EEG wave components in three immobility forms of the type of catalepsy (P-1), catatonia (P-2), and cataplexy (P-3) that form protosleep. The first three photostimulations promoted a gradual increase of the P-1 state to 84.16 +/- 11.6% [the initial value (IV) 22.9 +/- 9.1%] and a decrease of representation of wakefulness to 4.86 +/- 2/1% (IV 13.8 +/- 7.8%), of P-2 to 11.1 +/- 5.3 (IV 53.3 +/- 13.3%), and of P-3 to 2.21 +/- 1.0% (IV 11.1 +/- 5.6%). After 4-5 photostimulations and especially after their complete cessation the percentage of P-1 in the WPC was restored to initial values, whereas the percentage of the frog WPC P-3 considered to be a precursor of the homoiothermal sleep rose to 20 +/- 8.3% after 5 photostimulations and to 38.5 +/- 6.7% the next day. Changes in the frog EEG spectra appeared only after one photostimulation and were characterized by a brief increase of power of alpha-like waves and by inhibition of slow 6-waves. In P-2 the power of the slow delta-waves gradually rose. In P-3 the EEG parameters did not change. In all experimental animals a decrease of the relative thymus and adrenal masses was revealed, which indicates the photostimulation regime used in the work induces stress. The obtained data allow thinking that a certain neurohormonal response to stress has already been formed at the amphibian level and that an important role in this response realization is played by a coordinated interaction of the hypothalamic sleep-regulating system providing protosleep manifestations and of the hypothalamic neurosecretory system triggering the stress-reaction hormonal cascade.     

Sleep EEG spectral analysis in a diurnal rodent:Eutamias sibiricus

1. Sleep was studied in the diurnal rodent Eutamias sibiricus, chronically implanted with EEG and EMG electrodes. Analysis of the distribution of wakefulness, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep over the 24 h period (LD 12:12) showed that total sleep time was 27.5% of recording time during the 12 h light period and 74.4% during the 12 h dark period. Spectral analysis of the sleep EEG revealed a progressive decay in delta power density in NREM sleep during darkness. Power density of the higher frequencies increased at the end of darkness. Power density of the higher frequencies decreased and that of the lower frequencies increased during light. 2. Analysis of the distribution of vigilance states under three different photoperiods (LD 18:6; 12:12; 6:18) revealed that changes in daylength mainly resulted in a redistribution of sleep and wakefulness over light and darkness. Under long days the percentage of sleep during light was enhanced. The time course of delta power density in NREM sleep was characterized by a long rising part and a short falling part under long days, while a reversed picture emerged under short days. As a consequence, the power density during days. As a consequence, the power density during light was relatively high under long days. 3. After 24 h sleep deprivation by forced activity, no significant changes in the percentages of wakefulness and NREM were observed, whereas REM sleep was slightly enhanced. EEG power density, however, was significantly increased by ca. 50% in the 1.25-10.0 Hz range in the first 3 h of recovery sleep. This increase gradually decayed over the recovery night. 4. The same 24 h sleep deprivation technique led to a ca. 25% increase in oxygen consumption during recovery nights. While the results of the EEG spectral analysis are compatible with the hypothesis that delta power density reflects the 'intensity' of NREM sleep as enhanced by prior wakefulness and reduced by prior sleep, such enhanced sleep depth after sleep deprivation is not associated with reduced energy expenditure as might be anticipated by some energy conservation hypotheses on sleep function.     

Pinniped phylogeny and a new hypothesis for their origin and dispersal

The relationships and the zoogeography of the three extant pinniped families, Otariidae (sea lions and fur seals), Odobenidae (one extant species, the walrus), and Phocidae (true seals), have been contentious. Here, we address these topics in a molecular study that includes all extant species of true seals and sea lions, four fur seals and the walrus. Contrary to prevailing morphological views the analyses conclusively showed monophyletic Pinnipedia with a basal split between Otarioidea (Otariidae+Odobenidae) and Phocidae. The northern fur seal was the sister to all remaining otariids and neither sea lions nor arctocephaline fur seals were recognized as monophyletic entities. The basal Phocidae split between Monachinae (monk seals and southern true seals) and Phocinae (northern true seals) was strongly supported. The phylogeny of the Phocinae suggests that the ancestors of Cystophora (hooded seal) and the Phocini (e.g. harp seal, ringed seal) adapted to Arctic conditions and ice-breeding before 12 MYA (million years ago) as supported by the white natal coat of these lineages. The origin of the endemic Caspian and Baikal seals was dated well before the onset of major Pleistocene glaciations. The current findings, together with recent advances in pinniped paleontology, allow the proposal of a new hypothesis for pinniped origin and early dispersal. The hypothesis posits that pinnipeds originated on the North American continent with early otarioid and otariid divergences taking place in the northeast Pacific and those of the phocids in coastal areas of southeast N America for later dispersal to colder environments in the N Atlantic and the Arctic Basin, and in Antarctic waters.     

侧脑室注射促甲状腺激素释放激素对大鼠睡眠—觉醒的影响

采用多导睡眠描记术研究了例脑室注射促甲状腺激素释放激素(TRH)对正常大鼠和去甲状腺大鼠睡眠-觉醒的影响。在正常大鼠,TRH引起觉醒增加,浅慢波睡眠(SWS_1)、深慢波睡眠(SWS_2)和总睡眠时间(TST)均减少,异相睡眠(PS)消失,SWS_1、SWS_2和PS的潜伏期均显著延长,给药后立即产生效应并在1h内达高峰。去甲状腺对大鼠的睡眠-觉醒无明显影响,注射TRH后引起的效应与正常大鼠相似。结果提示TRH有促进大鼠觉醒的作用,对各睡眠时相均有抑制作用,其作用部位可能在下丘脑以外的中枢结构。     

Microinjection of glutamate into the pedunculopontine tegmentum induces REM sleep and wakefulness in the rat

The aim of this study was to test the hypothesis that the cells in the brain stem pedunculopontine tegmentum (PPT) are critically involved in the normal regulation of wakefulness and rapid eye movement (REM) sleep. To test this hypothesis, one of four different doses of the excitatory amino acid L-glutamate (15, 30, 60, and 90 ng) or saline (control vehicle) was microinjected unilaterally into the PPT while the effects on wakefulness and sleep were quantified in freely moving chronically instrumented rats. All microinjections were made during wakefulness and were followed by 6 h of polygraphic recording. Microinjection of 15- ng (0.08 nmol) and 30-ng (0.16 nmol) doses of L-glutamate into the PPT increased the total amount of REM sleep. Both doses of L-glutamate increased REM sleep at the expense of slow-wave sleep (SWS) but not wakefulness. Interestingly, the 60-ng (0.32 nmol) dose of L-glutamate increased both REM sleep and wakefulness. The total increase in REM sleep after the 60-ng dose of L-glutamate was significantly less than the increase from the 30-ng dose. The 90-ng (0.48 nmol) dose of L-glutamate kept animals awake for 2-3 h by eliminating both SWS and REM sleep. These results show that the L-glutamate microinjection into the PPT can increase wakefulness and/or REM sleep depending on the dosage. These findings support the hypothesis that excitation of the PPT cells is causal to the generation of wakefulness and REM sleep in the rat. In addition, the results of this study led to the identification of the PPT dosage of L-glutamate that optimally induces wakefulness and REM sleep. The knowledge of this optimal dose will be useful in future studies investigating the second messenger systems involved in the regulation of wakefulness and REM sleep.