Temperature acclimation and learning in fish

Summary Control fish acclimated at 21°C learned to swim upright following the attachment of floats to their ventral surfaces, while fish acclimated at both 5°C and 33°C failed to learn the swimming skill. Fish previously acclimated at 5°C and then transferred to 21°C 48 h before the task, learnt the swimming skill better than the control fish, but fish acclimated at 33°C and transferred to 21°C failed to acquire the new skill. Acclimation temperature, therefore, significantly modifies the learning behaviour of fish.     

Effects of the temperature of ice-seeding on survival of frozen-and-thawed mouse morulae

Summary Mouse morulae were frozen to –196°C in the presence of 1.2 M ethylene glycol or 1 M glycerol. After iceseeding in embryo samples at –10°C or below, the survival rates in vitro were lower than those obtained by ice-seeding between –4° and –8°C. The proportion morulae developing into live young in vivo after ice-seeding at –13°C and freezing was lower than that of embryos seeded at –4°C.     

Developmental patterns of supercooling capacity in a subantarctic wingless fly

Anatalanta aptera is a wingless fly which lives in subantarctic islands, particularly in sea bird colonies. Developmental patterns of supercooling capacity were studied in an experimental population reared at 5°C and fed ad libitum. Mean supercooling points of the eggs, second and third instar larvae, pupae, teneral and mature adults were –28.0°C, –10.8°C, –8.8°C, 17.6°C, –16.6°C and –8.2°C respectively. Low mean supercooling points were found for inactive stages (eggs, pupae) and, unexpectedly among Diptera, teneral adults. Mature adults had a combination of low supercooling ability, high lipid content and physogastry. The results are compared with those obtained in winged species from other families of Diptera.     

Motility of leukocytes in slide cells

Zusammenfassung Die Leukozytenbewegung wurde in Glaskammern während 24 h Inkubation beobachtet: die Kurve der Leukozytenbewegung besteht aus 2 Phasen, welche mittels 2 Exponentialgleichungen (durch das Wachstumsgesetz bestimmt) ausgedrückt werden können.In der vierten Stunde der Inkubation tritt eine Steigerung der Leukozytenbewegung auf.Die Leukozytenbewegung bei einer Temperatur von 30 und 40°C wurde mit der bei 37°C verglichen: Die Leukozytenbewegung ist bei 30°C langsamer und bei 40°C schneller als bei 37°C.     

Dämpfung des Kältezitterns durch Pentobarbital und Pethidin bei Ratten

Summary In rats, shivering was induced by cooling. Shivering started at 36.6°C in unanaesthetized rats and at 36.0°C in animals with light pentobarbital anaesthesia (5 mg/kg i.V.). Pethidine (2 mg/kg) lowered the onset of shivering in unanaesthetized rats to 35.3 °C and in anaesthetized animals to 33.0°C. The results suggest that the effect of pethidine upon shivering is potentiated by pentobarbital.     

Effects of low temperatures on survival of frozen-thawed mouse embryos

Summary Almost no damage to mouse morulae was observed between 0 and –40°C, and freezing damage to embryos in DMSO, glycerol or ethylene glycol occurred after exposure to –60, –50 or –50°C, respectively. Cooling embryos in DMSO or glycerol to temperatures below –50 to –60°C increased freezing damage. To the contrary, in the presence of ethylene, glycol, no more damage occurred after exposure to temperatures below –50°C.     

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).     

Resistance of cold-exposed rats to aflatoxin

Summary Male rats kept at a temperature of 4°–5°C were refractory to a lethal dose of aflatoxin compared to animals at 20°–21°C which exhibited a high mortality and marked liver damage. It is suggested that this decreased susceptibility is mediated through a stimulated microsomal drug-metabolizing system in cold environment.     

Effect of relative humidity on the free-living stages ofStrongyloides papillosus (Rhabdiasoidea: Nematoda)

Summary The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 °C and 25 °C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 °C than at 25 °C and 35 °C, and also they exhibit a poor resistance to desiccation.Acknowledgment. The author is grateful to Dr. Devendra Prasad of Patna University for his supervision and constant help in the work. The assistance of State University Grants Commission through a research scholarship is gratefully acknowledged.     

The induction of secondary seed dormancy by oxygen deficiency in a barnyard grassEchinochloa crus-galli

At 25°C, secondary dormancy was induced in seeds ofE. crus-galli exposed for 100 days to oxygen deficiency. By contrast, hypoxia did not induce dormancy at 15°C or prevent dormancy termination at 7°C. Secondary dormancy was terminated after 2 months stratification at 7°C. Oxygen deficiency may increase the proportion of dormant seeds in the soil, and affect the dynamics of the barnyard-grass soil seed bank.We thank Miss Jitka Králová for her excellent technical assistance.     

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.     

Ein Beitrag zur irreversiblen Temperaturinaktivierung der Gewebsatmung

Summary (1) Tissue slices of the liver and pieces of the skin of summer-frogs were incubated at 47.5°C for 30–150 min. Their respiration was measured during this incubation period and thereafter at a temperature of 37.5°C.(2) As a sign of an irreversible inactivation of the enzymes, the average respiration was inhibited. However, after certain periods of incubation at 47.5°C, over-shoot phenomena in the O₂-uptake at the temperature of 37.5°C were seen.     

Influence de la température de l'air ambiant sur quelques activités métaboliques d'animaux hétérothermes

Riassunto L'attività succinicodeidrogenasica dei mitocondri di fegato e di muscolo di rane tenute a varia temperatura, aumenta con l'aumentare di questa. La fosforilazione ossidativa si dimostra accoppiata a 5°C e a 20°C, mentre a 37°C presenta un completo disaccoppiamento.     

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.     

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.     

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.     

Lack of pituitary involvement in the cold-induced hyperglycemia of the killifish,Fundulus heteroclitus

Zusammenfassung Glukose-Steigerung im Serum vonFundulus heteroclitus nach Akklimatisation an –1,5°C wird nicht durch die Hypophyse verursacht. Hingegen ist die Hypophyse notwendig, um die Serumglukose bei 20°C bei normaler Konzentration zu halten. Hypophysektomie bei 20°C hat eine Abnahme der Serumglukose zur Folge.     

Effects of photoperiod,temperature and testosterone-treatment on plasma T3 and T4 levels in the Djungarian hamster,Phodopus sungorus

Summary The effects of photoperiod, temperature and testosterone treatment on plasma T₃ and T₄ levels were investigated in the Djungarian hamster. Plasma T₃ level was affected by temperature (25°C<7°C) but not by photoperiod. Plasma T₄ level was affected by photoperiod (short day < long day) at 25°C. Administration of testosterone increased plasma T₄ level under short photoperiod at 25°C. Thus, higher plasma T₄ level under long photoperiod at 25°C might be induced by testosterone.     

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.     

Veränderungen der thermoelastischen Kontraktion von Haut und Nerv bei alternden Tieren

Summary The thermo-elastic contraction which has been found to increase with age in the tendons, has been studied in the skin. This shows a contraction between 64–66°C similar to that of tendon fibres. In 22 month old rats, it reaches 5–6 times greater values than in 3 month old animals. The skin also shows a second contraction between 67 and 70°C. After the ninth month, in a continuously increasing degree, a third and fourth step of contraction appear at higher temperatures (up to 82°C).The sciatic nerve also shows a thermo-elastic contraction after the fourth month at 76–80°C. This increases with age, and, as in the case with the skin, several more steps of contraction appear at higher temperatures, up to 92°C. It is improbable that these thermo-elastic contractions are related to «elastin». The changes with increasing age, however, show a similarity to the age changes of «elastin» in so far as the thermic contractility increases with age.