Survival of ciliate protozoa under starvation conditions and at low bacterial levels

Under starvation conditions, 50% survivorship times displayed no significant relationship with cell size in 2 ciliate species in this study and 5 protozoan species from the literature. Differences in survival ability were attributed to differences in weight-specific respiratory rate and relative motility among these 7 species. At low bacterial levels, 4 ciliate species in this study displayed significant differences in survivorship. High survivorship ofEuplotes patella relative to that ofParamecium caudatum andParaurostyla sp. at low ciliate densities was attributed to the lower individual energy requirements of this smaller species. High survivorship ofStentor coeruleus was interpreted as an effect of its large quantity of reserves and low respiratory rate. The survivorship ofE. patella was reduced at a higher population density. Four ciliate species survived longer at 15C than at 22C. Q₁₀ values based on 50% survivorship times at these 2 temperatures were much lower than Q₁₀ values based on respiratory rates and growth rates of well-fed ciliates over a similar temperature range.     

High-resolution autoradiography of nuclear modifications during and after heat treatment ofNeurospora crassa

Summary The appearance of perinucleolar electron-dense spots in the nuclei of macroconidia ofNeurospora crassa incubated at 46C and their disaggregation after shift-down to 25 C have been investigated by high-resolution autoradiography after (5-³H) uridine pulses with or without chase periods. The RNA of these ribonucleoprotein-rich dense spots has been found to originate mainly from the heatsensitive nucleolus; after return to 25 C, the nucleolar activity was recovered and the RNA material stored either in an unprocessed or a mature rRNA form in the dense spots was found to be progressively extruded into the cytoplasm.     

Pineal melatonin rhythms in the lizardAnolis carolinensis: effects of light and temperature cycles

Summary Pineal and ocular melatonin was assessed, over 24 h periods, in male lizards (Anolis carolinensis) entrained to 24 h light-dark (LD) cycles and a constant 32 C, and in lizards entrained to both 24 h LD cycles and 24 h temperature cycles (32 C/20 C). At a constant temperature, the duration of the photoperiod has a profound effect on the duration, amplitude, and phase of the pineal melatonin rhythm (Fig. 1). The pineal melatonin rhythm under cyclic temperature peaks during the cool (20 C) phase of the cycle regardless of whether or not the cool phase occurs during the light or dark phase of a LD 1212 cycle (Fig. 3). Under a temperature cycle and constant dim illumination, a pineal melatonin rhythm is observed which peaks during the cool phase of the temperature cycle, but the amplitude of the rhythm is depressed relative to that observed under LD (Fig. 2). Illumination up to 2 h in duration does not suppress the nocturnal melatonin peak in theAnolis pineal (Fig. 4). No melatonin rhythm was observed in the eyes ofAnolis under either 24 h LD cycles and a constant temperature (Fig. 1), or under simultaneous light and temperature cycles (Fig. 3). Ocular melatonin content was, in all cases, either very low or non-detectable.Abbreviations HIOMT hydroxyindole-O-methyltransferase - NAT N-acetyltransferase     

Effect of light and temperature on the bleaching of the yellow mutant y-1 ofEuglena gracilis

Summary The yellow mutant y-1 ofEuglena gracilis, whose plastids are chlorophyll-deficient, is stable only in the dark and at suboptimal growth temperatures (below 26 C).At growth temperature of 30 C (in darkness) this strain is unstable and undergoes permanent bleaching. The process is enhanced by light so that bleaching may be increased up to 100 per cent. The degree of bleaching is proportional to light intensity.Bleaching is possible only during the active cell division. In the resting medium there is no bleaching, but total carotenoid synthesis is stimulated by illumination. At suboptimal growth temperature (26 C) the mutant is bleached only in the light, if light intensity exceeds 2,000 Lux. The results indicate that the process of bleaching in the yellow mutant is much more sensitive to temperature and light than in wild typeEuglena.     

Supraoptimal growth-temperature reduces the heat-shock sensitivity of the chrysophycean flagellatePoterioochromonas malhamensis

Summary The chrysophycean flagellatePoterioochromonas malhamensis shows some characteristic alterations after a sublethal heat-shock (42 C, 16 minutes). Most cells round up and retract their cytoplasmic tail. The lorica formation is affected and, in nearly all cells, flagellar activity. Most membrane systems, especially the dictyosome, are severely damaged. In contrast the flagellar root apparatus and the cortical microtubules seem to be unaffected.After growth at a supraoptimal temperature of 33 C and a subsequent heat-shock (42 C, 16 minutes) the cells do not show the heat injuries reported above. The ability to form the lorica becomes also adapted to higher temperatures.Possible adaptation mechanisms are discussed.     

Rhodopsin phosphorylation occurs at metarhodopsin II level

Photolyzed rhodopsin was phosphorylated in bovine rod outer segments incubated at –10 C. In the experiment in which urea-treated outer segments and rhodopsin kinase were incubated with ATP in the presence of 30% glycerol, the extent of phosphate incorporation at –10 C was about 30% of that at 37 C. Separation of phosphorylated rhodopsin by isoelectric focusing indicated that a limited number of sites were phosphorylated at –10 C. The partially phosphorylated pigment incorporated more phosphates when the temperatures was raised to 37 C. This was partly due to decreased inhibition of phosphorylation by glycerol at higher temperature. Since the maximum phosphorylation at –10 C (at which metarhodopsin II is stable) occurred at a pH value (6.0) lower than the pKa for metarhodopsin I-metarhodopsin II transition, metarhodopsin II was suggested to be the preferred substrate for rhodopsin kinase at –10 C. Limited proteolysis with thermolysin of rhodopsin phosphorylated at 37 C released peptides containing about 50% of the total phosphate incorporated. In contrast, proteolytic digestion of rhodopsin phosphorylated at –10 C released negligible amounts of phosphate-containing peptides. The results were taken to suggest that the incorporation of phosphates at metarhodopsin II level under the present condition occurred in the residues other than those removed by thermolysin digestion.Based on material presented at the Fifth International Congress of Eye Research, Eindhoven, October 1982     

Body temperature responses of Savanna Brown goat to the harmattan and hot-dry season

Rectal and vaginal temperature responses of the Savanna Brown goat indigenous to the Nigerian guinea savanna were determined during the harmattan and the hot-dry season. Measurements were made at 06:00h and at 14:00h after 8h exposure to field conditions. At the 06:00h measurements during the harmattan, all animals were observed to shiver. A significant (P<0.01) positive correlation was found between rectal (T_re) and vaginal temperatures. During the harmattan, mean T_re was 38.2C at 06:00h and 39.7C at 14:00h; the mean difference, T_re was 1.5C. During the hot-dry season, T_re at 06:00h was 38.1C, and at 14:00h, 38.7; T_re was 0.6C. It is concluded that the harmattan is thermally more stressful than the hot-dry season and that passive thermolability may not be an important mechanism in the Savanna Brown goat in adaptation to thermal stress.     

Interaction of cytochrome c L with methanol dehydrogenase from Methylophaga marina 42:

The reaction of methanol dehydrogenase with cytochrome c _L from Methylophaga marina and the reactions of the non-physiological substrates, Wurster's blue and ascorbic acid, with both proteins were studied as a function of temperature (4–32 °C), pressure (1–2000 bar) and ionic strength using the optical high pressure stopped-flow method. The thermodynamic parameters H, S and V were determined for all reactions where electron transfers are involved. These data allowed the determination of the Maxwell relationships which proved the internal thermodynamic consistency of the system under study. A conformational change on the cytochrome c _L level was deduced from both breaks in the Arrhenius plots and the variation of the V with temperature.Abbreviations MOPS 4-morpholinepropanesulfonic acid - CHES 2-(cyclohexylamino)ethanesulfonic acid - MDH methanol dehydrogenase - EDTA ethylenedinitrilotetraacetic acid disodium salt - BTB bromothymol blue (3,3-dibromothymolsulfoneph-thalein) - PQQ 2,7,9-tricarboxy-lH-pyrrolo-[2,3f]quinoline-4,5-dione - cytochrome c _HH mammalian horse heart cytochrome c     

The effect of ambient temperature on diurnal rhythm in heat production and activity in pigs kept in groups

The effect of ambient temperature on diurnal rhythm of metabolic rate and activity was studied in group housed pigs in two trials. Two climate controlled respiration chambers were used, one for each trial. Each chamber contained two groups of 8 pigs. During the experiment of 31 days the mean live weight of the animals increased from 28 to 40 kg. Feeding level was kept constant at 93 kg^–0.75. d^–1. Feed contained 12 kJ of metabolizable energy per g. Temperature treatment started with 20C for two days. After that it was lowered in stepwise fashion by 4K to 16, 12 and 8C. Each temperature treatment lasted two days. After that temperature it was increased in steps to 20C in 8 days. The whole procedure was repeated once. Metabolic rate and activity were measured continuously during the 24 hrs of every second day of the temperature treatment.Metabolic rate increased at temperatures below 16C. Activity was associated with ambient temperature. At low temperature, the total activity related heat production was increased, especially during day time. Variation in metabolic rate within a day was not reduced by low ambient temperature. Thermal requirement, calculated as lower critical temperature, was about 14C as averaged over the day, (16.1C during day time and 13.6C during night time). Extra thermal heat production below thermoneutrality was affected by time of day and activity.     

Cross bridge slippage in skinned frog muscle fibres

Mechanically skinned single fibres of the semitendinosus muscles of Rana esculenta were investigated at ca. 4 C. The fibres were activated by a Ca²⁺ jump technique, which allowed the development of a steady isometric tension within several seconds of entering a calcium rich solution at 4 C. Sequences of length changes of different duration and amplitude were applied to the fibre. It could be demonstrated that the fibre behaved as a Hookean spring in the case of small amplitude length changes (up to 0.5% L₀, ramp duration 0.5 ms) and that a sequence of length changes induced reversible changes in fibre state. In contrast, large stretches (> 1% L₀) induced a muscle give if the stretch were not immediately preceded by a release. The data was interpreted on the basis of a strain induced detachment of cross bridges in combination with a rapid reattachment of presumably the same cross bridges in a discharged position. The rates of strain induced detachment and reattachment depended on the stretch amplitude. At amplitudes exceeding 2% L₀ the rates were estimated to be at least several thousands per second.     

Thermoregulation in the hippopotamus

Measurements of the sub-lingual temperature and of the skin temperature of the nose, ears, neck, dewlap, sides and back of two hippopotami (HIPPOPOTAMUS AMPHIBIUS L.) in the Zoological Park at Wroclaw have been made. The mean sub-lingual temperature was 36.1C but a diurnal rhythm of sub-lingual temperature was evident, which was not related to changes in the environmental temperature. The skin temperatures varied with the environmental temperature. When the animals were immersed in water at 9C the sub-lingual temperature dropped to 24.5C but it had returned to its pre-immersion value within one hour of leaving the water.

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Zusammenfassung Es wurden Messungen der Sublingualtemperatur und der Temperatur der Haut an Nase, Ohren, Nacken, Wamme, Seiten und Rücken von 2 Hippopotamus (HIPPOPOTAMUS AMPHIBUUS L.) im Zoologischen Garten in Warschau vorgenommen. Die mittl. Sublingualtemperatur war 36.1C. Ein diurnaler Rhythmus ohne Beziehung zu den Änderungen der Umwelttemperatur konnte nachgewiesen werden. Die Hauttemperatur Änderte sichmit der Umwelttemperatur. Wenn die Tiere im Wasserbecken (9C) standen,fiel die Sublingualtemperatur auf 24,5C. Sie stieg nach Verlassen des Wassers innerhalb einer Stunde auf den Ausgangswert.

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Resume La température sublinguale ainsi que les températures cutanées du nez,de l'oreille, de la nuque, du ventre, des flancs et du dos ont été relevées chez deux hippopotamus (HIPPOPOTAMUS AMPHIBIUS L.) du Jardin Zoologique de Varsovie. La température sublinguale moyenne a été de 36,1C. L'existence d'un rythme nycthéméral indépendant des variations de la température ambiante a été observée.La température cutanée varie en fonction de la température ambiante.Quand les animaux se tenaient debout dans leur bassin d'eau froide à 9C, la température sublinguale tombait à 24,5C.Lorsque les animaux quittaient ce bassin, cette température remontait au bout d'environ b heure à sa valeur de départ.

     

Variations in mental performance under moderate cold stress

Effects of moderate cold stress on reasoning ability, associative learning and critical flicker frequncy of Indian subjects were studied by exposing them to 25C,. 20C, 15C and 10C for three hours. A second set of experiments was also conducted to confirm the conclusions of the first by using the same temperatures and duration of exposure. However, not only the sample used in the second case was larger and different but also the mental functions tested were numerical ability, running memory and mental alertness. It has been concluded that there is a significant impairment of simple cognitive functions at 15C which is 10C lower than their most comfortable temperature of 25C.     

Growth temperature acclimation byAmoeba proteus: Effects on cytoplasmic organelle morphology

Summary The effects on subcellular morphology of maintaining amoebae at temperatures other than 20 C (the routine culture temperature) were assessed. Estimations of cycling potential at each temperature confirmed that acclimation had affected gross cell functioning. Generation times ranged from no division at 6 C, to an optimal minimum of 2 days at 22 C.Organelle morphology changes were studied after 5 days of growth at the new temperatures; alterations were most evident at the extremes of 6 and 28 C. The main mitochondrial alteration resulted in changes to the ratio of Type I: Type II organelles; with a decrease in Type I forms away from the optimal range of 20–22 C. Extended culturing at 6 C generated mitochondrial matrical inclusions. Ribosomal attachment to the endoplasmic reticulum, a common feature of 20 C-grown cells, decreased at the temperature extremes, where an increase in free ribosomes occurred. Upon extended culture at 6 C helical structures, usually observed in groups only within the nucleus, were also present in the cytoplasm. Golgi complexes were less common in cells maintained at extreme temperatures and often showed differences in shape. These changes were all reversible on a return to culturing at 20 C.The possible functional significance of these findings is discussed.     

Effects of hyperthermia on enzymes and electrolytes in blood and cerebrospinal fluid in dogs

The effects of exposure to various degrees of heat stress on serum glutamate—oxaloacetate transaminase (SGOT), serum glutamate-pyruvate transaminase (SGPT), alkaline phosphatase (ALK-P-ase), calcium and chlorides have been studied on 75 dogs. Rectal temperature (T_re) was recorded before and after exposure to heat stress. These dogs were divided into 5 groups, according to the T_re level attained after exposure to heat stress. Rectal temperature was raised from normal to 39.45±0.47C in the first group, to 40.93±0.17C in the second group, to 41.87±0.22C in the third group, to 42.90 ± 0.21C in the fourth group and to 43.93±0.19C in the fifth group. The concentration of enzymes SGOT, SGPT and ALK-P-ase in blood and cerebrospinal fluid (CSF) increased significantly with hyperthermia. Calcium and chlorides concentrations in blood and in CSF tended to increase in hyperthermia. The integrity of the blood brain barrier for these enzymes and calcium is maintained under mild hyperthermia but it breaks down partially under influence of more severe hyperthermia. Core temperature above 41C results in damage to tissues and consequential rise of plasma enzymes. This degree of hyperthermia also seems to mark the beginning of injury to blood brain barrier. Critical core temperature tolerated by 50% of animals was 44C.     

Effect of protons and cations on chloroplast membranes as visualized by the bound ANS fluorescence

Structural changes in the chloroplast membranes caused by acidification and heat-treatment are studied by observing the changes in the fluorescence of ANS bound to thylakoid membranes. On addition of acids to buffered suspension of isolated pea chloroplasts, the fluorescence intensity of bound ANS shows a sigmoidal rise on reaching a pH value of about 4.5. A part of the fluorescence enhancement of bound ANS brought about by protons is not reversible on back titration with alkali. The reversible part of acid induced rise in ANS fluorescence possibly reflects structural changes expected to be associated with photophosphorylation. Divalent cations enhance the fluorescence of ANS bound to chloroplasts between a pH range 4.5–7.0 but diminish it if the pH is below 4.5.Addition of acid to heat-treated chloroplasts shows similar sigmoidal rise in ANS fluorescence intensity on lowering the pH to about 4.5. On addition of acid upto a pH of 3.1, the ANS fluorescence is greater than that of untreated chloroplasts, however, at pH below 3.1, the fluorescence of bound ANS is lower than the control chloroplasts. This observation indicates that heat-treatment caused some alteration of the microstructure of thylakoid membranes of chloroplasts besides the usual loss in the O₂ evolving capacity.This is further confirmed from the studies of Hill-activity and ANS binding to chloroplasts incubated at various temperatures in the absence and presence of aliphatic alcohol. Hill-activity (DCPIP reduction) of chloroplasts incubated at temperatures between 25 C and 55 C first increases reaching a maximum at 45 C and then declines rather sharply, when the chloroplasts are heated beyond 45 C (Tmax). The presence of 200 mM n-butyl alcohol or 40 mM n-amyl alcohol during the warming treatment lowers the temperature by 8 C at which the decline in the Hill-activity is observed. An enhancement in the fluorescence intensity and a blue shift of the emission spectrum of bound ANS are noted if the chloroplasts are heated beyond the Tmax either in absence or presence of alcohol. The changes in the fluorescence of ANS bound to heat-treated chloroplasts plausibly reflect the nature of the structural changes in chloroplasts during the heating upto 55 C.Abbreviations ANS 1-anilino-8-naphthalene sulphonate - DCPIP 2,6-dichlorophenol indophenol     

Changes in the diameter of microtubules connected with the autonomous rotary motion of the lipotubuloids (elaioplasts)

Summary The lipotubuloids ofOrnithogalum umbellatum consisting of osmiophilic granules surrounded by a system of microtubules move from one place to another within a cell by means of a progressive rotary motion.It was proved that the rotary motion of the lipotubuloids is autonomous, while their progressive motion depends on cyclosis. DNP causes cyclosis to stop earlier than does the rotary motion of the lipotubuloid. The peripheral speed of the rotating lipotubuloid reaches 31.4/sec and is 6.2 times faster than the maximum speed of the cytoplasmic motion.The diameter of microtubules in the lipotubuloids changes, and these changes are connected with the lipotubuloid motion. Those rotating at a speed of 60 to 360/sec consist of two equally numerous populations of microtubules:A) from 14 to 20 nm, andB) from 22 to 28 nm. In the lipotubuloids whose rotation is considerably slower, the great majority of microtubules are 14 to 20 nm in diameter, and the B population constitutes only 10%. The immobilization of the quickly rotating lipotubuloids through the action of DNP results in destruction of the two microtubule populations, so that only one population is present. This has intermediate diameters ranging from 16 to 24 nm. The removal of DNP restores the intense rotary motion of the lipotubuloids and brings about the reappearance of the population of microtubules ranging from 22 to 28 nm in diameter.The increase in microtubule diameters results most probably from shortening of the microtubules. It can be supposed that the contraction of microtubules is the source of the motive force responsible for the rotary motion of the lipotubuloids.     

Estimation ofEscherichia coli mortality in seawater by the decrease in3H-label and electron transport system activity

The mortality ofEscherichia coli in seawater was assessed by viable counts, electron transport system activity, and cellular³H-labelling. Filtration was used to assess the grazing mortality. Cellular radiolabelling and electron transport system activity were useful methods for assessingE. coli survival in seawater. The decrease in the³H-label as a method to assess bacterial mortality was validated by using viable counts and metabolic activity assays. The particulate fraction that passed 2 m but was retained on 0.2 m pore-size filters was the primary reason forE. coli mortality in seawater.     

Thermal stability of soluble mitochondrial H+-ATPase

ATPase melting has been studied by circular dichroism and differential scanning microcalorimetry. Decomposition of the -helix of H⁺-ATPase (in which about 80% of the peptide groups of the enzyme are involved) following thermal treatment is shown to proceed gradually, beginning with room temperature. Effect of nucleotides upon melting is detected in the range of 20–40 C. Above 40 C, the pattern of thermal decomposition of the three-dimensional structure of H⁺-ATPase is independent of the nature of nucleotides present. Highly stable -helical sites have been found in the enzyme molecule. Possible mechanism of formation of such sites is discussed, and the results obtained are compared with data on thermal stability of ATPase from thermophilic bacteria. Structural changes in the molecule following thermal treatment are compared with ATPase activity changes under similar experimental conditions.     

The effects of age and artificial acclimatization on the survival of rats in cold

Clipped,young Holtzman rats can be made to withstand cold exposure of 5 C as a result of adaptive mechanisms which are activated during pre-acclimatization.These mechanisms are less pronounced in clipped mature rats and seem to decline with age. Where inherent adaptive mechanisms are unable to allow the rat to withstand exposure to 5C,treatment with thyroid hormones seems to impart an artificial acclimatization which permits the survival of mature as well as of old, clipped rats in the cold.

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Zusammenfassung Geschorene junge Hotzmann Ratten können gegen die Haltung bei 5C widerstandfÄhig werden auf Grund von Anpassungsfunktionen, die wÄhrend der Vorakklimatisation aktiviert werden.Diese Funktionen sind in geschorenen erwachsenen Ratten weniger ausgeprÄgt und scheinen mit dem Alter an Wirksamkeit zu verlieren. Wo angeborene AdaptationskrÄfte für die Ratte nicht ausreichen den Aufenthalt bei 5C zu ertragen, scheint die Behandlung mit Schilddrüsenhormonen eine künstliche Akklimatisation zu geben, die das überleben von erwachsenen und alten geschorenen Ratten ermöglicht.

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Résumé De jeunes rats Holtzman tondus peuvent devenir résistants á une température de 5C, grâce à des mécanismes d'adaptation activés pendant la pré-acclimatation. Cette faculté est moins marquée chez les rats tondus adultes et semble diminuer avec l'âge. Si les mécanismes normaux d'adaptation ne suffisent pas à développer la résistance à 5C, les hormones thyroidiennes semblent conférer une acclimatation artificielle permettant la survie des rats tondus adultes et âgés.

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Supported in part by Grants H-3901 and H-6778 from the National Institutes of Health, Bethesda, Maryland, U.S.A.     

Variations cardio-respiratoires et metaboliques à l'effort sous-maximal (P=40% Pmax) et maximal (Vita Max) en conditions thermiques froide (0‡C) et neutre (20‡C)

Resume Cette étude a pour but d'étudier les variations physiologiques et métaboliques tant au repos, qu'au cours d'efforts physiques de longue durée (2h) à 40% de la puissance maximale et d'efforts exhaustifs dans des conditions d'hypothermie ambiante (0C) en comparaison de valeurs recueillies en conditions thermiques neutres (20C). L'ensemble des épreuves furent exécutées en chambre climatique par: d'une part 11 sujets mâles pour l'effort exhaustif et d'autre part 8 sujets mâles pour l'exercice sous-maximal. Nous avons observé une légère bradycardie à 0C pour nos deux groupes à la fin de l'effort. La VO₂ et la ventilation pulmonaire sont plus élevées à 0C lors de l'effort maximal, nous observons toutefois le phénomène inverse lors de l'exercice sousmaximal. Les concentrations plasmatiques en acide lactique sons moins élevées et les bicarbonates plus élevés en ambiance thermique froide pour les deux conditions expérimentales. Le pH et la température rectale demeurent stables. Le RQ ne présente pas de différences significatives à la fin de chacun des deux efforts à 20C et 0C.

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The purpose of this study is to investigate the responses on cardiorespiratory and metabolic level measured at rest, during a long-term (2 h) submaximal exercise (P=40% Pmax) and during an exhaustive exercise (Vita Max) and recovery time in normal (20C) and in hypothermic (0C) conditions. The ergometric exercises were performed by 11 male subjects (Vita Max) and 8 male subjects (submaximal exercise) in a climatic room. We have observed a slight but mostly not significant (P<.05) bradycardia for both groups at the end of the exercise. VO₂ and pulmonary ventilation are higher at the end of the maximal exercise performed at 0C, this phenomenon is reversed for the submaximal exercise. The lactate concentrations are lower at 0C. For the same temperature the bicarbonates are higher. pH and T rect are not different in both experimental conditions and RQ is not significantly affected by temperature variations.