Temporal and spatial differences in the emission of calls by pipistrelle bats<Emphasis Type="Italic">Pipistrellus pipistrellus</Emphasis> and<Emphasis Type="Italic">P. pygmaeus</Emphasis>

The number of orientation, feeding and social calls emitted by pipistrelle batsPipistrellus pipistrellus Schreber, 1774 andP. pygmaeus Leach, 1825 was recorded throughout the night at eight different sites. Social calls were unaffected by weather variables, whereas orientation calls and feeding buzzes were both significantly affected by cloud and temperature conditions. The number of emissions of each call type was significantly different between sites, indicating that the bats used different sites for different activities. Significant positive correlations between all three combinations of call types occurred only during the middle of the night, corresponding with the nadir of flying insects. This suggests that bats were engaged in activities other than feeding at this time, such as territory protection or mate attraction.     

The energy cost of echolocation in pipistrelle bats (Pipistrettus pipistrellus)

Summary A positive relationship was established between energy expenditure and pulse rate of echolocation for 8 pipistrelle bats (Pipistrellus pipistrellus) when hanging at rest in a respirometry chamber at 28 °C. The least squares fit equation: Energy expenditure (J·^–1·h^–1)=110.09+ 40.3 pulse rate (n/s) explained 14% of the minute by minute variation in energy expenditure. For a 6 g bat therefore each pulse costs approximately 0.067 Joules to produce. The net cost of echolocation at 10 pulses per second for a 6 g pipistrelle bat was predicted to be 9.5 × BMR with a range of 7.0–12.2 × BMR. We suggest that since a major portion of the cost of echolocation may result from contraction of the pectoralis and scapularis groups of muscles, the cost of echolocation is reduced for flying animals which contract these muscles anyway during flight. This may account for the high incidence of echolocation systems amongst flying vertebrates, when compared with terrestrial species.     

Fertility of the early postpartum, lactating domestic rabbit

Sixty-four crossbred primiparous lactating does each suckling six pups were allocated at random into four groups and were mated on either Day 1, 2, 3, or 4 post partum (where Day 0 = the day of parturition). They were subsequently killed on Day 10 post coitum (where Day 0 = the day of mating) to assess fertility. There were no significant differences between treatment groups in their mating response (97% overall), ovulation response (77% overall), implantation response (83% overall), implantation rate (8.7 overall), or preimplantation mortality rate (24% overall). Ovulation rate was significantly increased in does mated on Days 3 and 4 (13.3 and 13.1, respectively), compared with those mated on Day 1 (10.2, P<0.05) and Day 2 (9.6, P<0.01) post partum. From these results we conclude that fertility is high throughout the early postpartum period in the lactating rabbit.     

Immunological identification of uncoupling protein in interscapular "brown" adipose tissue of suckling and adult pipistrelle bats (Pipistrellus pipistrellus).

1. Interscapular adipose tissue of suckling and adult pipistrelle bats was examined for the presence of the 32,000 Mr "uncoupling protein" diagnostic of brown adipose tissue. 2. Following separation by SDS-polyacrylamide gel electrophoresis, mitochondrial proteins were blotted onto nitrocellulose and probed for uncoupling protein with an anti-(ground squirrel uncoupling protein) serum. 3. Immunoreactivity consistent with the presence of uncoupling protein was found in all samples of adipose tissue mitochondria from both suckling and adult bats. 4. It is concluded that interscapular adipose tissue in pipistrelle bats exhibits the critical biochemical criterion for being designated functionally "brown".     

Evaporative water loss in two sympatric species of vespertilionid bat, Plecotus auritus and Myotis daubentoni: relation to foraging mode and implications for roost site selection

Simultaneous measures of oxygen consumption and evaporative water loss (EWL) were made in two species of temperate-zone vespertilionid bat ( Plecotus auritus and Myotis daubentoni ; mean body mass 9.12 and 10.12g, respectively) at ambient temperatures (T_a) of 5, 15 and 25°C and variable vapour pressure deficit. EWL was directly dependent on vapour pressure deficit and oxygen consumption and inversely dependent on T_a. EWL was significantly greater in P. auritus than in M. daubentoni. A model for EWL in P. auritus under a variety of environmental conditions (5–25°C and 20–80% relative humidity) suggested that EWL from bats in shallow summer torpor will be lowest at low T_a, and that, except at low (> 50%) relative humidity, EWL from euthermic bats will be lowest at high T_a. At low relative humidity (< 20%), resting bats could lose over 30% of body mass per day (24 h) through evaporation. At high T_a (> 25°C), EWL from euthermic bats could be over 65% lower at high (> 80%) compared to low (< 20%) relative humidity. In bats in shallow summer torpor at low (5°C) T_a the equivalent saving was > 96%. At low relative humidity predicted EWL from bats in shallow summer torpor was 34 to 81% of that from euthermic bats, and at low T_a and high relative humidity was only 2%. In the wild, M. daubentoni has freer access to drinking water than does P. auritus and yet EWL at rest was higher in the latter species. We suggest that post-prandial dumping of urinary water by M. daubentoni leads to a limit in the amount of body water available to this species to cover evaporative losses once within the day roost, which in turn has led to an adaptation of physiology towards the minimization of EWL when at rest.     

Circadian rhythm gene regulation in the housefly Musca domestica

The circadian mechanism appears remarkably conserved between Drosophila and mammals, with basic underlying negative and positive feedback loops, cycling gene products, and temporally regulated nuclear transport involving a few key proteins. One of these negative regulators is PERIOD, which in Drosophila shows very similar temporal and spatial regulation to TIMELESS. Surprisingly, we observe that in the housefly, Musca domestica, PER does not cycle in Western blots of head extracts, in contrast to the TIM protein. Furthermore, immunocytochemical (ICC) localization using enzymatic staining procedures reveals that PER is not localized to the nucleus of any neurons within the brain at any circadian time, as recently observed for several nondipteran insects. However, with confocal analysis, immunofluorescence reveals a very different picture and provides an initial comparison of PER/TIM-containing cells in Musca and Drosophila, which shows some significant differences, but many similarities. Thus, even in closely related Diptera, there is considerable evolutionary flexibility in the number and spatial organization of clock cells and, indeed, in the expression patterns of clock products in these cells, although the underlying framework is similar.     

A quasi-elastic light scattering and cinematographic investigation of motile Chlamydomonas reinhardtii.

Quasi-elastic light scattering and cinematographical techniques were used to investigate the motility of Chlamydomonas reinhardtii (wild type). It was found that quantitative information on the trajectory of motion was required for a meaningful interpretation of the autocorrelation functions. Two models for describing the oscillatory motion of the cell were developed; one based on the instantaneous forward-and-backward motion of the cell, and the other based on a sinusoidal perturbation to the average forward motion. Both models gave satisfactory agreement with the shape of the experimentally measured autocorrelation function, thus making it possible to use this measurement to determine mean progressive swimming velocities in a population of greater than 200 cells.