BEHAVIOUR OF A RADIO-TAGGED TILAPIA RENDALLI BOULENGER IN LAKE NGEZI,ZIMBABWE

SUMMARY

The behaviour of a single specimen of Tilapia rendalli Boulenger was observed June through October 1986 in Lake Ngezi, Zimbabwe, by the use of a surgically-implanted radiotransmitter. The individual displayed a distinct homing response on two occasions, returning to the cove of capture (1) 1.5 km away within 48 hours of release (95Z of the distance was covered in 24 hours), and (2) after a lengthy migration some 6.0 km up the lake with other tilapia. During the only observed migration in late June, the fish travelled a conservative distance of 6.7 km over a 5-day period, sometimes at rates > 150 m/hr. The fish was also characterized by strong territoriality (i.e., preference to the cove of capture) and avoidance to the approach of the researcher by boat.     

Superiority of radiotelemetry over the tail-cuff method in evaluating control and drug-induced data in cardiovascular functions

The aim of the study was to compare an often-used method to measure blood pressure (BP) using a tail-cuff (TC) device, with radiotelemetry (RT) which allows to sample data on heart rate (HR) and BP in freely moving rodents without any restraint in behaviour. Data were collected in male normotensive Wistar-Kyoto rats and in spontaneously hypertensive rats. Experiments were performed under 12:12 h light–dark conditions (lights on at 07:00 h) with simulated dawn and dusk for 45 min. Experiments were performed at 08:00–10:00 h (rest phase) and at 20:00–22:00 h (activity phase) under control conditions and after treatment with the beta-adrenoceptor blocker metoprolol (8 mg/kg). For TC, the Harvard BP Monitoring System (Edenbrigde, England) and for RT radio transmitters (Dataquest IV system, TA11PA-C40, DSI, St. Paul, Minnesota, USA) were used. Rats bearing the TC device were also monitored under RT. The experiments show that TC significantly increased HR and both systolic and diastolic BP in both strains and both at L and D. Metoprolol reduced TC-induced HR but left BP increase uneffected. The study shows that RT is the method of choice to monitor BP and HR in rodents, TC is not suitable.     

Thermal ecology of the Australian agamid Pogona barbata

This study compares the thermal ecology of male bearded dragon lizards (Pogona barbata) from south-east Queensland across two seasons: summer (1994–1995) and autumn (1995). Seasonal patterns of body temperature (T _b) were explored in terms of changes in the physical properties of the thermal environment and thermoregulatory effort. To quantify thermoregulatory effort, we compared behavioral and physiological variables recorded for observed lizards with those estimated for a thermoconforming lizard. The study lizards' field T _bs varied seasonally (summer: grand daily mean (GDM) 34.6 ± 0.6°C, autumn: GDM 27.5 ± 0.3°C) as did maximum and minimum available operative temperatures (summer: GDM T _max 42.1 ± 1.7°C, T _min 32.2 ± 1.0°C, autumn: GDM T _max 31.7 ± 1.2°C, T _min 26.4 ± 0.5°C). Interestingly, the range of temperatures that lizards selected in a gradient (selected range) did not change seasonally. However, P. barbata thermoregulated more extensively and more accurately in summer than in autumn; lizards generally displayed behaviors affecting heat load nonrandomly in summer and randomly in autumn, leading to the GDM of the mean deviations of lizards' field T _bs from their selected ranges being only 2.1 ± 0.5°C in summer, compared to 4.4 ± 0.5°C in autumn. This seasonal difference was not a consequence of different heat availability in the two seasons, because the seasonally available ranges of operative temperatures rarely precluded lizards from attaining field T _bs within their selected range, should that have been the goal. Rather, thermal microhabitat distribution and social behavior appear to have had an important influence on seasonal levels of thermoregulatory effort. Received: 28 April 1997 / Accepted: 29 December 1997     

Annual and seasonal space use of different age classes of female wild boar Sus scrofa L.

In a radiotelemetric study, we analysed space use of 24 female specimens (14 family groups and 14 nonreproductive yearling females) out of 23 wild boar groups for periods between 3 and 39 months. Generally, wild boar used relatively small areas, showed high site fidelity but also a strong individual variation of home ranges, indicating a high flexibility in space use. Although age-specific differences were not statistically significant, female yearlings tended to have larger mean annual home ranges (1,185 ha MCP) than animals ranging in family groups (771 ha). Yearlings also showed a stronger shifting from spring to summer home ranges (2,345 m) and a tendency towards larger home range sizes in summer (791 ha MCP), compared to family groups (shift 1,766 m, MCP 461 ha). Yearlings displayed a dislocation of about 1 km of the annual centre in the first year after dividing from the mother. In contrast, in adults older than 2 years, the dislocation of the annual center was only 240 m.     

实验围栏内越冬眼镜蛇体温调节和低温耐受性的无线电遥测

用SB 2T内置热敏无线电发射器、HOBO和TINYTALK数据记录块等电子设备研究实验室围栏内越冬眼镜蛇 (Najaatra)的体温调节和低温耐受性。围栏内总平均气温 (10 6℃ )与总平均巢温 (10 9℃ )无显著差异 ,但气温变化幅度 (- 2 0～ 37 4℃ )大于巢温变化幅度 (6 5～ 14 5℃ )。眼镜蛇体温变化幅度 (3 4～34 1℃ )介于气温和巢温的变化幅度之间 ,平均体温的个体间差异显著 ,总平均体温 (15 0℃ )大于平均气温和平均巢温。最低体温的平均值为 8 9℃ ,与经验估测的眼镜蛇低温耐受极限 (9 0℃ )相近。白天气温高于15℃时能见到巢外调温个体 ,其体温记录次数约占处于此条件下的个体总体温记录次数的 2 9%。巢外调温个体的体温高于处于晚间和白天 15℃以下气温个体的体温 ,亦高于处于白天 15℃以上气温但不进行巢外调温个体的体温。处于白天 15℃以下气温个体的体温低于晚间个体的体温。处于白天 15℃以上气温但不进行巢外调温个体的体温与处于晚间和白天 15℃以下气温个体的体温无显著差异。处于晚间和白天 15℃以下气温个体的体温与气温呈显著的正相关 ,表明眼镜蛇在低温和缺乏热斑块的环境中是体温调节的顺应者。气温高于 15℃时 ,进行巢外调温和不进行巢外调温个体的体温均与气温无关 ,表明眼镜蛇在气温     

A radio-telemetric study of the thermoregulation of free living water monitor lizards,Varanus S. salvator

Eight water monitor lizards, Varanus s. salvator, were captured; four individuals from an oil palm estate on the Malayan peninsula, and four from fresh water-deficient Tulai island 65 km off-shore in the South China Sea. They were fitted with a radio transmitter attached to a thermistor which was inserted into the cloaca of the animals and released. The heating rate during basking was measured as 0.117 and 0.118 °C·min^-1 while the daily cloacal temperature fluctuated between 29.5–37.3 °C. Cloacal temperature was measured on other individuals caught at random times during the day, which revealed a considerable daily and individual variation. The average cloacal temperature during activity was 30.4 °C. The peak activity appeared when body temperature was 31 °C. Thermoregulation by behavioural means included cooling in water and reducing heat loss at night by sleeping in burrows. The cooling rate for two individuals when submerged in 29 °C water was 0.308 and 0.340 °C·min^-1. There appeared to be a strong correlation between ambient temperature and cloacal temperature.Abbreviations bw body weight - T _a ambient temperature - T _a body temperature - T _c cloacal temperature - TOP Timor Oil Palm Estate - TUL Tulai Island     

Estrus detection and estrus characteristics in housed and pastured Holstein-Friesian cows

This study compared three methods of estrus detection and characteristics of standing estrus between dairy cows kept in cubicle housing and fed a total mixed ration diet (HOUSED treatment) and those kept at pasture with concentrate ration supplementation (PASTURE treatment). The 23 spring-calved Holstein-Friesians in each treatment were monitored by three estrus detection methods simultaneously—visual observations, tail paint and radiotelemetry (HeatWatch)—for 9 wk. Milk progesterone profiles were used to determine the dates of true standing estrus events. All three detection methods had a higher efficiency of estrus detection in the PASTURE treatment than in the HOUSED treatment (P < 0.001), but there was no difference in the accuracy of estrus detection between the two treatments (P > 0.05). Within each treatment there was no difference between the efficiency and accuracy of the three methods (P > 0.05). HeatWatch was as efficient as visual observations at detecting standing estrus events. However, during visual observation sessions all occasions when animals were observed standing to be mounted were not recorded by HeatWatch. More cows expressed sub-estrus events and fewer expressed standing estrus events in the HOUSED than in the PASTURE treatment (P < 0.05). The interval between parturition and the second standing estrus was longer in the HOUSED treatment than in the PASTURE treatment (P < 0.05). All three detection methods were much less effective in the HOUSED than in the PASTURE treatment. This is because all of the detection methods tested relied solely on standing to be mounted and this was reduced in the HOUSED cows. Alternative approaches to estrus detection are needed for cows kept indoors on concrete.     

Effects of a seven-day continuous infusion of ropivacaine on circadian rhythms in the rat

The present study was conducted to evaluate the effect of a 7 d continuous infusion of ropivacaine on the 24 h rhythms of body temperature, heart rate, and locomotor activity. After an initial 7 d baseline, rats were randomly divided into two groups of 4 rats each to receive ropivacaine or saline via an osmotic pump for 7 consecutive days. The pumps were removed thereafter and observed during a 7 d recovery span. The studied circadian rhythms were measured by radiotelemetry throughout each of the 7 d periods. An additional group of 4 rats was studied under the same experimental conditions to assess the plasma levels of ropivacaine on days 3 and 8 following pump implantation. Our results indicate that ropivacaine does not induce loss of the circadian rhythms of body temperature, heart rate, or locomotor activity; a prominent period of 24 h was found for all variables in all animals, before, during, and after ropivacaine treatment. However, ropivacaine treatment did modify some characteristics of the rhythms; it increased the MESOR (24 h mean) of the heart rate and locomotor activity rhythms and advanced the acrophase (peak time) of the locomotor activity circadian rhythm. The present study indicates that the circadian rhythms of heart rate and locomotor activity are modified after continuous infusion of ropivacaine, which is of particular interest, given the potential cardiotoxicity of this local anesthetic agent.     

Dispersal of Camellia japonica seeds by Apodemus speciosus revealed by maternity analysis of plants and behavioral observation of animal vectors

Seed dispersal determines a plant’s reproductive success, range expansion, and population genetic structures. Camellia japonica, a common evergreen tree in Japan, has been the subject of recent genetic studies of population structure, but its mode of seed dispersal has been assumed, without detailed study, to be barochory. The morphological and physiological features of C. japonica seeds, which are large and nutritious, suggest zoochorous dispersal, however. We compared actual distances between mother trees and seedlings with distances attributable to gravity dispersion only, to test the zoochory hypothesis of C. japonica. The animals that transport the seeds for caching were identified experimentally. We also examined the extent to which seed dispersal is affected by the behavior of animal vectors. Seed dispersal by Apodemus speciosus was confirmed by taking photographs of animals that were consuming seeds experimentally deposited on the ground. Camellia seeds hoarded by the rodents under the litter or soil were protected from drying. On the basis of microsatellite analysis of maternal tissue from the seed coat, the mother trees of 28 seedlings were identified. Maternity analysis revealed the average seed-dispersal distance from mother trees was 5.8 m±6.0 SD, a distance greater than initial dispersal by gravity alone. These results indicate that C. japonica is a zoochorous species dispersed by A. speciosus. Fifty percent of the seed dispersal occurred from mature evergreen forests to dwarf bamboo thickets. This directional seed dispersal would contribute to range expansion of C. japonica. Home range sizes of A. speciosus were 0.85 ha at most and covered with different types of vegetation, from evergreen forests to grassland. This low specificity of their microhabitat use might enhance seed dispersal to different types of vegetation.All animal experiments complied with Japanese laws.     

Effects of a Seven‐Day Continuous Infusion of Ropivacaine on Circadian Rhythms in the Rat

The present study was conducted to evaluate the effect of a 7 d continuous infusion of ropivacaine on the 24 h rhythms of body temperature, heart rate, and locomotor activity. After an initial 7 d baseline, rats were randomly divided into two groups of 4 rats each to receive ropivacaine or saline via an osmotic pump for 7 consecutive days. The pumps were removed thereafter and observed during a 7 d recovery span. The studied circadian rhythms were measured by radiotelemetry throughout each of the 7 d periods. An additional group of 4 rats was studied under the same experimental conditions to assess the plasma levels of ropivacaine on days 3 and 8 following pump implantation. Our results indicate that ropivacaine does not induce loss of the circadian rhythms of body temperature, heart rate, or locomotor activity; a prominent period of 24 h was found for all variables in all animals, before, during, and after ropivacaine treatment. However, ropivacaine treatment did modify some characteristics of the rhythms; it increased the MESOR (24 h mean) of the heart rate and locomotor activity rhythms and advanced the acrophase (peak time) of the locomotor activity circadian rhythm. The present study indicates that the circadian rhythms of heart rate and locomotor activity are modified after continuous infusion of ropivacaine, which is of particular interest, given the potential cardiotoxicity of this local anesthetic agent.