Serotonin levels in fish brain: Effects of hydrostatic pressure and water temperature

Summary The contents of serotonin (5 HT) and its metabolite 5 hydroxy indoleacetic acid (5 HIAA) have been measured (HPLC technique) in the brains of eels exposed to different conditions of hydrostatic pressure and temperature (HP=1 or 101 ATA in winter, Tw=14°C, and in summer, Tw=19°C). It appears that an increase of Tw induces a significant increase of the 5 HT/5 HIAA ratio. In contrast, eels exposed at 101 ATA of HP for 1 h do not exhibit any modification in the 5 HT/5 HIAA brain ratio at a given temperature. The involvement of 5 HT under the conditions studied is discussed.     

Hibernation at moderate temperatures: a continuation of slow wave sleep

Summary Golden-mantled ground squirrels (Citellus lateralis) displayed virtually continuous electrophysiological states of sleep when hibernating at moderate ambient temperatures (22°C). Rapid-eye-movement sleep progressively diminished with the fall in body temperature so that at a body temperature of 23°C it was completely absent. At this temperature hibernation was characterized by slow wave sleep isomorphic with slow wave sleep episodes at non-hibernating (euthermic) body temperatures.Supported by National Institute of Health grants GM 23694 awarded to R.J. Berger and GM 23695 awarded to H.C. Heller.     

Antifreeze agents in the body fluid of winter active insects and spiders

Summary Insects and spiders which are active at subzero temperatures on snow in winter are found to be protected against internal freezing by antifreeze agents present in their body fluid. The body fluid has a melting point of about –1 °C, but the antifreeze agents prevent growth of ice crystals at temperatures down to –6 to –7 °C.Acknowledgment. We would like to thank Anne Lohrman for her kind help in collecting insects and spiders.     

Mixed life cycles in the transitional zone between voltinisms in the fall webworm,Hyphantria cunea

The fall webworm,Hyphantria cunea Drury, was introduced from North America into Japan at half a century ago. At present, the populations north of 36° N are bivoltine and those south of 36° N are trivoltine. In the present study, the life cycle in the transitional zone between voltinisms was clarified in Tsukuba (36.1° N). When fourth instar larvae of the second generation were collected in the field and maintained in the laboratory, the incidence of pupal diapause increased when the sampling date was delayed from 16 August to 5 September. The fact that some developed without diapause inidcates the occurrence of a trivoltine life cycle in this locality, where a bivoltine life cycle is predominant. The critical photoperiod for diapause induction at 20 and 25°C was 14 h 13 min and 14 h 10 min, respectively. The photoperiodic response may explain the rapid increase in diapause incidence in late summer. In laboratory-reared diapause pupae, the time and period of chilling (5°C) greatly influenced the time required for adult emergence at the final incubation temperature of 25°C. However, diapause pupae chilled for a sufficiently long period developed to adulthood rapidly, irrespective of the conditions before chilling. Therefore, the difference in timing of entering diapause between pupae of the second and third generations would not result in their temporal reproductive isolation in the following spring. It is concluded that the mixed voltinism in Tsukuba is not a result of a mixture of genetically distinct bivoltine and trivoltine populations, but a result of the phenotypic plasticity in a genetically rather homogeneous population.     

The effects of temperature on ATPase activity and force generation in skinned muscle fibers from the Pacific blue marlin (Makaira nigricans)

Summary ATPase activity and force generation have been measured simultaneously in isolated, demembranated muscle fibers of the Pacific blue marlin (Makaira nigricans) between 0 and 30°C. Tension generation is relatively independent of temperature above 15°C and falls with a Q₁₀ of <1.5 on decreasing the temperature to 0°C. In contrast, the Q₁₀ for ATPase activity is 2.2 over the range 0–30°C. The results are interpreted in terms of the cross bridge theory of contraction.     

Photoperiod-induced changes in temperature-metabolism curve,shivering threshold and body temperature in the pigeon

Summary A short photphase combined with cold-acclimation changed the shivering threshold of the pigeon from 21 to 14 °C. The change of critical temperature was also found in the temperature-metabolism curve. A long photophase both alone and combined with warm-acclimation induced a reduction of body temperature to a lower level (about 2°C) at all ambient temperatures, ranging from 5 40°C.     

Experimentally induced encapsulation ofDiplostomum phoxini (Faust) in the fish host

Summary Experimentally induced encapsulation ofDiplostomum by the hostPhoxinus, is recorded for the first time and requires the metacercariae to develop in fish at a temperature (23–26°C) which is above that naturally encountered.Acknowledgment. It is a pleasure to thank M. R. L. Johnston for his advice.     

Growth ofEchinococcus multilocularis in gerbils exposed to different environmnntal temperature

Summary Gerbils kept at high (35°C) temperature harbored a significantly largerEchinococcus multilocularis cyst biomass than those kept at room (21°C) and low (5°C) temperature. Parasite induced adrenomegaly was observed in all temperature groups.Acknowledgments. I am indebted to Miss Marianne Hardy and Mr Terry Durham for their excellent technical assistance.     

Temperature dependence of neurotransmitter release in the antarctic fishPagothenia borchgrevinki

Summary The quantal contents of endplate potentials from extraocular muscles of an antarctic fishPagothenia borchgrevinki were measured over a range of temperatures. Quantal release was maximal at about 5°C but showed little dependence on temperature between –2°C and 10°C. Above 10°C quantal content declined until release ceased about 18°C. In view of the fact that the ambient temperature at which these fish live is constant at –1.9°C, the results suggest thatPagothenia borchgrevinki is only partially adapted to its environment despite 25 million years acclimatization.The authors wish to thank the staff of New Zealand's Scott Base, Antarctica, without whose cooperation the work would have been impossible. Mr J. Quinn of the Auckland University Physiology Department gave invaluable assistance with computing and electronics and the Antarctic Division of the New Zealand Department of Scientific and Industrial Research provided transportation and logistic support. The project was financially supported by the New Zealand University Grants Committee and the Auckland University Research Committee. S.P. was a Senior Fellow of the N.Z. Medical Research Council.     

Influence of posttreatment temperature on the toxicity of pyrethroid insecticides to susceptible and resistant larvae of the Egyptian cotton leafworm,Spodoptera littoralis (Boisd.)

Summary The organophosphorus insecticides chlorpyrifos, leptophos, and phosfolan and the carbamate methomyl was found to be more toxic to larvae of a susceptible strain ofSpodoptera littoralis (Boisd.) when the posttreatment temperature was increased from 20 to 35°C. In contrast, the pyrethroids permethrin, fenvalerate, deltamethrin, cypermethrin, and flucythrinate were more toxic at 20°C than at 35°C. This effect was more pronounced in the pyrethroid-resistant strains. Evidently, resistance levels were reduced at low temperature. However, the application of piperonyl butoxide or DEF in combinations with the tested pyrethroids on R-strains resulted in reducing the effect of temperature.     

Effect of cold exposure on electrophysiological properties of rat heart

Male rats exposed to the cold (4°C) for five or ten days exhibited modifications in their thyroid state, as documented by increases in serum thyroid hormone levels, to which differently graded modifications of heart weight/body weight ratio, heart rate, and resting metabolic rate were associated. The values of the above mentioned thyroid state indicators returned to those of the control when the animals, kept at cold for ten days, were re-exposed to room temperature (24°C) for an additional 10 days. The configuration of action potentials, recorded in vitro at 26°C from fibres of anterior papillary muscles, was different in control rats of different age and was affected by prolonged cold exposure. In fact, the action potential duration (APD) increased after ten days of cold exposure. In the re-exposed group the APD was not different from that of the controls. Such a pattern was not significantly modified when the stimulation frequency increased from 1 Hz to 5 Hz. The above results suggest that in cold exposure, as in experimental hyperthyroidism, thyroid hormone might exert a cardiac chronotropic effect by modifying heart electrophysiological properties. Thus thyroid hormone should play a basic role during the exposure to cold environment, stimulating the body metabolism and increasing heart rate as a response to the requirement for greater tissue perfusion.     

Environmental temperature and the growth ofTaenia crassiceps cysticerci in mice

Summary Mice kept at low (5±1 °C) and high (35±1 °C) temperature harboured significantly lessTaenia crassiceps cysticerci than controls kept at 21±1 °C. This effect was more pronounced in heat-stressed than in cold-stressed animals and more in males than in females.     

Effect of water temperature on the motility ofPelagia noctiluca (Forksal)

Summary Laboratory tests have been performed, on the behavior of the jellyfishPelagia noctiluca as a function of the water temperature. It has been found that the usual contractions of the umbrella are almost completely missing at 6°C; they begin to appear at about 7–8°C and they reach frequencies of about 10 and 40 per min at 11 and 15°C respectively. An ambient temperature of about 11°C appears to be a threshold value below which this kind of medusa ceases to move actively and sinks, while at higher temperatures it gradually begins to shift, showing a positive thermotropism in the presence of temperature gradients greater than about 0.01 °C/cm.This work was supported by grant No. 80.00748.88 from the National Research Coucil of Italy (CNR).     

Body temperatures of lambs and their mothers measured by radio-telemetry during parturition

Using temperature-sensitive radio-telemeters chronically implanted in the abdomens of 8 fetal lambs and their mothers, we measured body temperature changes induced by parturition. Maternal body temperature rose at 0.70±0.06 °C/hour (mean±SEM) in the final stages of labour. Fetal body temperature also rose, but at a significantly lower rate, 0.45±0.06 °C/hour (p<0.05). The fetus appears to be protected from excessive hyperthermia during the birth process.     

Induction of cyst formation by low temperature in the dinoflagellateGonyaulax polyedra Stein: Dependence on circadian phase and requirement of light

Encystment, which at a temperature of 15°C is photoperiodically controlled inGonyaulax polyedra, can also be induced by a decrease of temperature, from 20 to 10 or 8°C in the absence of photoperiodic signals. The cyst-inducing capacity of the decrease in temperature depends on the circadian phase: in constant light, the maximum of sensitivity was found at the beginning of subjective night. In a light/dark cycle, however, cyst formation was reduced during dark phase, indicating that light is required for the process of encystment. A similar light dependence was seen in the effect of the physiologically occurring cyst inducer 5-methoxytryptamine, but not in the encystment response to the protonophores monensin and nigericin.     

Temperature-dependent activity of mosquito larvicidal factor(s) present inBacillus sphaericus 1593–4 and 1691

Summary The larvicidal factor(s) ofBacillus sphaericus 1593–4 and 1691 was more active at high temperature (33–35 °C) as compared to low temperature (23–25 °C) for the larvae ofCulex fatigans andAnopheles subpictus.     

Photoperiodic summation is temperature-dependent inPyrrhocoris apterus (L.) (Heteroptera)

Summary InPyrrhocoris apterus, a low temperature, 15°C, prevented the termination of diapause by long days and, unexpectedly, also the induction of diapause by short days. Both responses were enabled at a higher temperature, 26°C. In contrast to current concepts, it was proved that the summation of photoperiodic signals was temperature-dependent, since the morphogenetic development was prevented by starvation.     

The effect of chronic heat stress on cortisol levels in the antarctic fishPagothenia borchgrevinki

Radioimmunoassay was used to determine levels of the stress-inducible glucocorticoid, cortisol, circulating in the plasma of the extremely stenothermal Antarctic fishPagothenia borchgrevinki at rest and after heat stress. Fish sampled immediately after capture (–1.9°C) had low cortisol levels (10.4±1.4 ng ml^–1, mean±SEM) as did fish which were laboratory rested for 3 days. Sudden exposure to 5°C (48h) resulted in a peak cortisol value after 3 h (69.9±6.8 ng ml^–1) whereas exposure to 8°C (6h) resulted in a peak value after 1 h (73.5±8.0 ng ml^–1). At both temperatures levels remained significantly elevated (p<0.05) for the entire period of exposure. Increased temperature also resulted in a significant change in haemoglobin, haematocrit and mean cell haemoglobin concentration (MCHC) (p<0.05). Plasma lactate was significantly elevated only after exposure to 8°C (p<0.05). Plasma cortisol levels fromP. borchgrevinki are reported here for the first time and show this cryopelagic Antarctic species to have an unusual hormonal stress profile.     

A mild winter delays supercooling point elevation in freeze tolerantChymomyza amoena larvae (Diptera: Drosophilidae)

Summary Supercooling point elevation to –3.2±1.3°C among 17 freeze tolerantChymomyza amoena larvae was delayed until January, 1983 in the mild winter of 1982–83 and occurred despite particulate matter in the gut. The larval population in mid-Michigan is polymorphic for both freeze tolerant and freeze sensitive larvae. One substrate,Malus coronaria fruits, appears to be a neutral niche supporting both phenotypes in the population.Discussions with K. E. Zachariassen and J. Duman before beginning the work onC. amoena cold-hardiness were invaluable. Visits of both at Michigan State University were jointly sponsored by the Depts. of Zoology and Entomology. H. Carson suggested thatC. ameona might be breeding in endemic crabapples. G. Parmalee at MSU showed one of us (HTB) a long established thicket ofMalus coronaria. The MSU Climatology Center supplied all Lansing area weather data.     

Stability of ceftizoxime in aqueous solution

Summary Ceftizoxime, when assayed using the disc agar-diffusion method withBacillus subtilis ATCC 6633 as the indicator microorganism in buffered (pH 6) medium, retains its potency in aqueous solution at 4°C for about 3 months. Even after 4 months, some residual activity can be found. However, when this solution was assayed on the non-buffered medium, a seemingly quicker but misleading loss of potency was observed. This resulted from inadequate sensitivity of the assay. The sensitivity of the ceftizoxime assay was increased by lowering the incubation temperature from 37°C to 30°C. The pH- and incubation temperature-dependent potency must be kept in mind when assaying ceftizoxime.