The effect of collagenase and temperature on mitochondrial respiratory parameters in saponin-skinned cardiac fibers

The results of a comparative study of the respiration rates of mitochondria in saponin-skinned rat cardiac fibers (SF) and in fibers treated with saponin and collagenase (SCF) suggest that only about half of the whole population of mitochondria manifest their activity in SF, in contrast to SCF, in response to extracellular substrates of oxidative phosphorylation. The apparent K_m value for ADP with succinate as substrate, which was as high as 330±32 M in SF in SF at 20 °C, decreased about 2-fold in SCF at the same temperature and in SF at 37 °C, and decreased further to 67±8 M in SCF at 37 °C. Thus, weakening or breaking of cellular contacts by collagenase and the temperature-dependence of diffusion of substrates such as ADP, seem to be important factors that determine the respiratory activity and regulatory parameters of mitochondria in saponin-permeabilized cardiomyocytes.     

Impact of elevated CO2 and increased temperature on Japanese beetle herbivory

To examine how the major elements of global change affect herbivory in agroecosystems, a multifactorial experiment was conducted where soybeans were grown at two levels of carbon dioxide and temperature, including those predicted for 2050, under otherwise normal field conditions. Japanese beetles (Popillia japonica Newman) were enclosed on foliage for 24 h, after which the beetle survivorship, total and per capita leaf consumption, and leaf protease inhibitor activity were measured. The direct effect of temperature on beetle consumption and survivorship also was measured under controlled environmental conditions. No differences in total foliage consumption were observed; however, beetles forced to feed at elevated temperature in the field demonstrated greater per capita consumption and reduced survivorship compared to beetles feeding at ambient temperature. Survivorship was also greater for beetles that consumed foliage grown under elevated CO₂, but there were no interactive effects of CO₂ and temperature, and no differences in leaf chemistry were resolved. Leaf consumption by beetles increased strongly with increasing temperature up to ～37° C, above which increased mortality caused a precipitous decrease in consumption. An empirical model based on the temperature dependence of leaf consumption and flight suggests that the 3.5°C increase in temperature predicted for 2050 will increase the optimal feeding window for the Japanese beetle by 290%. Elevated temperature and CO₂ operating independently have the potential to greatly increase foliage damage to soybean by chewing insects, such as Popillia japonica, potentially affecting crop yields.     

Dynamics of Escherichia coli at elevated temperatures: effect of temperature history and medium

Aims: The dynamics of Escherichia coli near the maximum temperature for growth in a rich medium are analysed. The effects of temperature history, medium composition and physiological state of the inoculum are evaluated. Methods and Results: Kinetics of E. coli K12 MG1655 is studied in ‘brain–heart infusion’ broth in a temperature controlled environment. Based on viable counts, ‘smooth’ growth curves are observed at 40, 41, 42 and 43°C. The exponential growth phase at 44 and 45°C is interrupted. At 46°C, a period of exponential growth is followed by inactivation. Neither the physiological state of the inoculum nor medium enrichment alters the dynamics, whilst temperature pre‐adaptation or chemical chaperones restore regular cell growth and division (‘smooth’ exponential growth). Conclusions: Atypical, nonexponential growth at 44, 45 and 46°C seems related to protein destabilization and can (partly) be restored by an appropriate medium design (i.e. addition of chemical chaperones) or temperature history (i.e. selection of a more resistant subpopulation). Significance and Impact of the Study: This study indicates that the maximum temperature for growth is dependent on the temperature history and the chemical environment. These observations and the nonexponential kinetics have important implications for the development of predictive models for food safety and quality.     

The effect of body temperature on the hunting response of the middle finger skin temperature

The relationship between body temperature and the hunting response (intermittent supply of warm blood to cold exposed extremities) was quantified for nine subjects by immersing one hand in 8°C water while their body was either warm, cool or comfortable. Core and skin temperatures were manipulated by exposing the subjects to different ambient temperatures (30, 22, or 15°C), by adjusting their clothing insulation (moderate, light, or none), and by drinking beverages at different temperatures (43, 37 and 0°C). The middle finger temperature (T _fi) response was recorded, together with ear canal (T _ear), rectal (T _re), and mean skin temperature (Tˉ _sk). The induced mean T _ear changes were −0.34 (0.08) and +0.29 (0.03)°C following consumption of the cold and hot beverage, respectively. Tˉ _sk ranged from 26.7 to 34.5°C during the tests. In the warm environment after a hot drink, the initial finger temperature (T _fi,base) was 35.3 (0.4)°C, the minimum finger temperature during immersion (T _fi,min) was 11.3 (0.5)°C, and 2.6 (0.4) hunting waves occurred in the 30-min immersion period. In the neutral condition (thermoneutral room and beverage) T _fi,base was 32.1 (1.0)°C, T _fi,min was 9.6 (0.3)°C, and 1.6 (0.2) waves occurred. In the cold environment after a cold drink, these values were 19.3 (0.9)°C, 8.7 (0.2)°C, and 0.8 (0.2) waves, respectively. A colder body induced a decrease in the magnitude and frequency of the hunting response. The total heat transferred from the hand to the water, as estimated by the area under the middle finger temperature curve, was also dependent upon the induced increase or decrease in T _ear and Tˉ _sk. We conclude that the characteristics of the hunting temperature response curve of the finger are in part determined by core temperature and Tˉ _sk. Both T _fi,min and the maximal finger temperature during immersion were higher when the core temperature was elevated; Tˉ _sk seemed to be an important determinant of the onset time of the cold-induced vasodilation response. Accepted: 29 April 1997     

Chiral discrimination of the enantiomers of δ-phenyl-δ-valerolactone by cellulose triacetate: A chromatographic and microcalorimetric study of the thermodynamics

The resolution of racemic δ-phenyl-δ-valerolactone by chromatography on cellulose triacetate CTA I results in one of the best separations of optical antipodes observed so far on this chiral stationary phase. The thermodynamics of the stereoselective interaction of the enantiomers of δ-phenly-δ-valerolactone have been studied by chromatography at different temperatures and by direct microcalorimetric investigations of the complexation with CTA I. This analysis suggests that the separation process is mainly controlled thermodynamically and that kinetic effects, if any, play a minor role. Microcalorimetric titration experiments indicate that specific (optimum) complexation sites on CTA I for the stronger retained enantiomer of δ-phenly-δ-valerolactone are rapidly saturated, whereas the first eluted enantiomer seems to interact much less selectively with defined interaction sites on the chiral polymer matrix. © 1993 Wiley-Liss, Inc.     

The effect of sodium chloride on phage formation by staphylococci at elevated temperatures

In experiments with the K strain of Staphylococcus aureus and the K race of bacteriophage suspended in tryptose phosphate broth and maintained at 42 degrees C. it was found that the presence of 1 M NaCl produced certain drastic changes in the relationship between the host cells and the infecting virus: 1. Staphylococci grown at 42 degrees C. in plain broth or in NaCl-broth are "activated," i.e. when growth is stopped by lowering the temperature to 5 degrees C. and phage is added, the activity titre immediately displays a rise of 15- to 16-fold. 2. 1 M NaCl tends to prevent the sorption of phage by cocci and this effect is more pronounced at 42 degrees C. than at 5 degrees C. When the activation test is conducted at 5 degrees C. (the usual temperature) most of the phage is picked up by the cells and the described increase in activity titre follows. If the test takes place at 42 degrees C. there is little sorption and correspondingly little rise in phage titre. 3. Mixtures of staphylococci and phage incubated at 42 degrees C. in NaCl-broth fail to produce phage; the final plaque and activity titres are identical with the initial titres. Here, also, the influence of 1 M NaCl in preventing contact of phage with cocci appears to account for the results. 4. Similar mixtures held at 42 degrees C. in plain broth exhibit a drop of about 60 per cent in activity and plaque titres. The loss of phage may be due to adsorption on dead cells accumulating in the suspension or to the thermolability of the bacterium-phage complex, or to both.     

The effect of temperature on DNA structural transitions under the action of Cu2+ and Ca2+ ions in aqueous solutions

The work examines the structural transitions of DNA under the action of Cu2+ and Ca2+ ions in aqueous solution at temperatures of 29 and 45 degrees C by ir spectroscopy. Upon binding to the divalent ions studied, DNA transits into the compact state both at 29 and 45 degrees C. In the compact state DNA remains in B-form limits. The compaction process is of high positive cooperativity. As temperature increases the divalent metal ion concentration required to induce DNA compaction decreases in the case of Cu(2+)-induced compaction and increases in the case of Ca(2+)-induced compaction. It is suggested that the mechanism of the temperature effect on DNA compaction in the presence of Cu2+ ions possessing higher affinity for DNA bases differs from that of the temperature influence on Ca(2+)-induced DNA compaction. In the case of copper ions the determining factor is the increase of binding constants of the Cu2+ ions interacting with the denatured parts formed on DNA while in the case of calcium ions it is the decreased screening action of counterions upon the increase of their hydration with temperature. The efficiency of divalent metal ions studied in inducing DNA compaction depends on hydration of counterions. DNA compaction occurs in a narrow interval of Cu2+ concentrations. As the Cu2+ ion concentration increases, DNA compaction is replaced with Cu(2+)-induced DNA aggregation. At elevated temperatures Cu(2+)-induced DNA compaction could acquire a phase transition character.     

The effect of elevated temperature on the aggregation of African green monkey kidney cells

The aggregation kinetics of African green monkey kidney cells CV1 and of the SV40 transformed derivative COS1 cells that had been incubated at 37 degrees C or 43.5 degrees C was studied using the shaking flask system. COS1 cells show a three fold decrease in aggregation rate compared to CV1 cells when both cell types were incubated and aggregated at 37 degrees C. When these cell types were incubated at 43.5 degrees C for 5 hours, then aggregated at 37 degrees C showed a faster aggregation kinetics than before. Their aggregation at 43.5 degrees C with prior incubation at 37 degrees C or 43.5 degrees C reached the aggregation kinetics of 43.5 degrees C incubated cells aggregated at 37 degrees C. The addition of serum in the aggregation medium did not influence extensively the aggregation rates of both cell types.     

The effect of root temperature on rose plants in relation to air temperature

Rose plants (Rosa hybrida ‘Sonia’=‘Sweet Promise’) were grown in heated (minimum night temperature 17°C), and unheated greenhouses with or without root heating to 21°C. These trials covered 6 growth cycles extending over two winter seasons. In the heated greenhouse, root heating did not increase yield, flower quality or plant development. In the unheated greenhouse, root-heated plants grew as well as those in the air-heated greenhouse as long as the air temperature did not fall below 6°C. When minimum night temperatures fell below 6°C, growth, yield and quality were reduced, irrespective of root temperature. Daytime plant water relations were studied in plants growing at 6 different root temperatures in the unheated greenhouse. Leaf resistance to water diffusion was lowest at optimal root temperature. Total leaf water potential was not significantly affected by root temperature.     

Effect of elevated concentrations of sodium chloride and temperature on the state of erythrocyte cytosol

It was shown by means of ESR-spin probe method that microviscosity of erythrocyte cytosol had a limiting value which could be reached by various concentrations of sodium chloride depending on temperature. With a temperature decrease when reaching this value haemolysis occurs.     

The effect of shoot-root ratio and temperature on K+ influx in rye

The temperature sensitivity of K⁺ influx into rye roots and root plasma membrane ATPase activity were compared in plants grown at different temperatures. It was shown that ATPase activity obeyed the Arrhenius relationship with temperature, whereas K⁺ influx into intact plants was linearly related to temperature and markedly influenced by shoot/root ratio. A model for acclimation of K⁺ influx to low temperatures based on the regulation of the K⁺ carrier mechanism by plant demand for K⁺ is described.     

高温调控对黄瓜霜霉病菌侵染的影响

采取温湿度相结合的方法来研究高温处理对黄瓜霜霉病菌（Pseudoperonospora cubensis Rostov)侵染的影响,比较研究了35－50℃4个温度梯度、50％－90％5个湿度组合处理对病菌致病性的影响。同一相对湿度条件下,随着温度的上升病菌致病性降低;40－50℃的高温范围内,在同一温度下随着湿度的不断升高,受处理病菌的致病能力逐渐下降。在RH80％以上、温度40℃以上时,病菌的致病力随着处理时间的延长而变弱;45℃以下的高温高湿处理病菌超过1h,病菌基本上没有致病性。通过高温控制苗期黄瓜霜霉病的研究,确定高温高湿防治苗期黄瓜霜霉病的最佳温湿度为45℃1h(RH80%)。通过高温致死菌诱导植株抗性的研究,初步明确高温处理致死的病菌可以短期诱导植株的抗性。     

The temperature dependence of the acute toxicity of copper to a freshwater pond snail,Viviparus bengalensis L.

Static bioassays with copper (as CuSO₄ · 5H₂O) were conducted in laboratory with a freshwater pond snailViviparus bengalensis, at different environmental temperatures. The 96 hr LC50 values in ppm of Cu were 0.060 at 32.5 °C; 0.066 at 24 °C; 0.09 at 27.3 °C and 0.39 at 20.3 °C. In higher copper concentrations some behavioural changes such as secretion of mucus, discharge of eggs and embryos were noted. The results indicate that toxicity to copper increases with temperature increase.     

The effect of fleece on core and rumen temperature in sheep

Temperature loggers were implanted to record core body temperature (T_core) and rumen temperature (T_rumen) in sheep. The relationship between T_core and T_rumen was compared for fleeced and shorn Merino sheep over a range of environmental temperatures and during stressors involved with shearing. Fleeced sheep maintained higher T_core and T_rumen than shorn sheep in all environmental conditions tested (from thermoneutral up to 33 °C and 55% relative humidity). Shearing of the fleeced sheep resulted in those sheep having a lower T_core when exposed to hot conditions, compared to the previously shorn sheep. Respiratory rates of fleeced sheep followed similar patterns and were higher than shorn sheep under all environmental conditions. After the fleeced sheep were shorn, their respiratory rates decreased to rates similar to the previously shorn sheep when under heat load, suggesting heat loss other than respiratory evaporative heat loss was augmented.     

The effect of temperature on the behaviour and development of Triatoma brasiliensis

Abstract. The effects of temperature on the development of early stages and the thermopreference of nymphs and adults were analysed in the haematophagous bug Triatoma brasiliensis Neiva, 1911 (Hemiptera, Reduviidae). Egg hatching, mortality of nymphs, feeding and moulting success of the early stages of T. brasiliensis were all affected by temperature. While high rates of egg hatching were observed between 25 and 27 °C, no hatching occurred at 12, 19 and 38 °C. The mortality of first‐instar nymphs was highest at 38 °C, at which no insects survived after 10 days of exposure. Feeding success was only affected at the lowest temperature (12 °C). No ecdysis was observed in the groups exposed to 12, 19 and 21 °C. Recently fed fourth‐instar nymphs preferred to stay at a temperature of approximately 30 °C. The preferred temperature began to decline gradually to approximately 27 °C during ecdysis, reaching 26 °C at 30 days after ecdysis. After a second blood meal, the insects' preferred temperature was again approximately 30 °C. The thermopreference pattern of females was similar to that of nymphs. Nymphs and females showed a daily fluctuation in their preferred temperature, moving towards higher values at the beginning of the dark phase, and choosing lower ones after this time interval, at which they remained until the end of the light phase. The females laid their eggs in all sectors of the arena, although the largest numbers of eggs were found between 28 and 32 °C.