Individual differences in temperature perception: Evidence of common processing of sensation intensity of warmth and cold

The longstanding question of whether temperature is sensed via separate sensory systems for warmth and cold was investigated by measuring individual differences in perception of nonpainful heating and cooling. Sixty-two subjects gave separate ratings of the intensity of thermal sensations (warmth, cold) and nociceptive sensations (burning/stinging/pricking) produced by cooling (29°C) or heating (37°C) local regions of the forearm. Stimuli were delivered via a 4?×?4 array of 8 mm?×?8?mm Peltier thermoelectric modules that enabled test temperatures to be presented sequentially to individual modules or simultaneously to the full array. Stimulation of the full array showed that perception of warmth and cold were highly correlated (Pearson r?=?0.83, p?<?0.05). Ratings of nonpainful nociceptive sensations produced by the two temperatures were also correlated, but to a lesser degree (r?=?0.44), and the associations between nociceptive and thermal sensations (r?=?0.35 and 0.22 for 37 and 29°C, respectively) were not significant after correction for multiple statistical tests. Intensity ratings for individual modules indicated that the number of responsive sites out of 16 was a poor predictor of temperature sensations but a significant predictor of nociceptive sensations. The very high correlation between ratings of thermal sensations conflicts with the classical view that warmth and cold are mediated by separate thermal modalities and implies that warm-sensitive and cold-sensitive spinothalamic pathways converge and undergo joint modulation in the central nervous system. Integration of thermal stimulation from the skin and body core within the thermoregulatory system is suggested as the possible source of this convergence.     

Thresholds of microwave-evoked warmth sensations in human skin

We measured thresholds for microwave-evoked skin sensations of warmth at frequencies of 2.45, 7.5, 10, 35, and 94 GHz. In the same subjects, thresholds of warmth evoked by infrared radiation (IR) were also measured for comparison. Detection thresholds were measured on the skin in the middle of the back in 15 adult male human subjects at all microwave (MW) frequencies and with IR. Long duration (10-s), large area (327-cm²) stimuli were used to minimize any differential effects of temporal or spatial summation. Sensitivity increased monotonically with frequency throughout the range of microwave frequencies tested. The threshold at 94 GHz (4.5 ± 0.6 mW/cm²) was more than an order of magnitude less than at 2.45 GHz (63.1 ± 6.7 mW/cm²), and it was comparable to the threshold for IR (5.34 ± 1.07 mW/cm²). Bioelectromagnetics 18:403–409, 1997. © 1997 Wiley-Liss, Inc.     

Quantification of deep and superficial sensibility in saline-induced muscle pain-a psychophysical study

The aim of the present study was to study the sensibility in the area of saline-induced muscle pain. In three experiments, ten subjects were exposed to computer-controlled infusion of 0.5 ml isotonic (0.9%) or hypertonic (9%) saline into the anterior tibial muscle. The pain intensity was assessed on a visual analogue scale (VAS). The pain threshold (PT) to pressure and electrical stimulation in muscle and subcutaneous tissues was determined. Three experiments were performed in which infusion of hypertonic saline produced significantly higher VAS scores than isotonic saline. In all three experiments, there was no significant difference in PT obtained after infusion of isotonic saline compared with infusion of hypertonic saline. In experiment 1, the PT was determined at the infusion site and 4 cm from the infusion site. At the infusion site, the pressure PT decreased (- 19 2%) 1, 3, 5, 7 and 9 min after infusion of isotonic and hypertonic saline, but remained unchanged 4 cm from the infusion site. The intramuscular electrical PT at the infusion site and 4 cm from the infusion site increased significantly (29 6%) 5, 7 and 9 min after saline infusion. In experiment 2, the pressure PT and the intramuscular electrical PT were recorded after two infusions of saline separated by 1 day. The day after the first infusion, the pressure PT was decreased compared with the PT before the first infusion, but the electrical PT was not affected. Moreover, the hypertonic saline infusion given on the second day produced significantly higher (130 50%) VAS scores than the infusion given on the first day. In experiment 3, the PT was determined in the subcutaneous tissue, but no significant effects of saline infusion were found. The present placebo-controlled experiments failed to show muscular or subcutaneous hyperalgesia after saline-induced muscle pain per se.     

低温冷藏对不同虫期啊氏啮小蜂存活率的影响

研究啊氏啮小蜂Tetrastichus hagenowii(Ratzeburg)不同发育阶段在10℃贮存不同天数对其存活率的影响。结果表明,啊氏啮小蜂卵期冷藏10d、20d,其发育历期分别较对照延长6.6d、9.4d,平均每粒卵荚出蜂量比对照分别少10头、9.8头,冷藏卵荚的出蜂率较对照无差异,卵期冷藏30~90d,卵荚出蜂率为0。啊氏啮小蜂幼虫期冷藏10~90d,其发育历期较对照延长1.8~26.3d,平均每粒卵荚出蜂量、卵荚孵化率较对照分别下降5.6~50.3头、8.4%~70.4%。啊氏啮小蜂蛹期冷藏10~90d,其发育历期较对照缩短3.4~17.5d,平均每粒卵荚出蜂量和卵荚孵化率均随冷藏天数增加而明显降低。     

Effects of alternating exposure to cold and heat for 14 days on cold tolerance in winter

People are exposed to heat regularly due to their jobs or daily habits in cold winter, but few studies have reported whether parallel heat and cold exposure and diminish cold acclimation. This study was conducted to investigate the effects of alternating exposure to cold and heat on cold tolerance in eight young males. A daily acclimation program to cold and heat, which consisted of 2-h sitting at 10 °C air in the morning and 2-h running and rest at 30 °C air in the afternoon, was conducted for 14 consecutive days. Eight male subjects participated in a cold tolerance test (10 °C [ ± 0.3], 40%RH[ ± 3]) before (PRE) and after (POST) completing the alternating exposure program. During the cold tolerance test, subjects remained sitting upright on a chair for 60 min. Rectal temperature (T_re) was lower in POST than in PRE during the 60-min cold tolerance test (P = 0.027). During the cold tolerance test, systolic, diastolic, and mean arterial blood pressures in POST were lower than those in PRE (P = 0.006, P = 0.005, and P = 0.004). No significant differences in skin temperatures between PRE and POST were found for the cold tolerance test. There were no significant differences in energy expenditure during cold exposure between PRE and POST. Subjects felt less cold in POST than in PRE (P = 0.013) whereas there was no significant difference in overall thermal comfort between PRE and POST. These results suggest that cold adaptation can still occur in the presence of heat stress.     

Temporal relationships between warmth imagery and associated changes in digital pulse amplitude, skin temperature and skin temperature sensation

Temporal relationships between warmth imagery and associated psychophysiological changes were studied by recording digital pulse amplitude, skin temperature, and thermal sensations in 5 subjects. After each trial the subjects were asked whether they thought they had been successful in producing the expected mental image. During the subjectively successful imagery tasks the digital pulse amplitude and the skin temperature of the hand rose significantly. The subjective onset of imagery took place after the digital pulse amplitude had started to change but before the skin temperature had begun to rise. This implies that mental imagery of skin warming as a conscious experience is not a prerequisite of somatic change. The thermal sensation (i.e. feeling of warmth) took place while the skin temperature was rising or immediately after that. This suggests that it is not caused by the mental image per se but by activation of skin temperature receptors.     

Enhancement of supercooling capacity and survival by cold acclimation, rapid cold and heat hardening in Spodoptera exigua

Insects can increase their resistance to cold stress by prior exposure to non-lethal cold temperatures. Here, we investigated the supercooling capacity and survival of eggs, 3rd and 5th instar larvae, and pupae of Spodoptera exigua (Lepidoptera: Noctuidae) during CA, and responses to various pre-treatment protocols, including constant temperatures, thermoperiods, and RCH, RHH, RCH + RHH and RHH + RCH combined with thermoperiods. Only acclimated eggs demonstrated a significant decrease in SCP, from −20.7 ± 0.3 to −22.9 ± 0.3 °C, among all experimental groups compared to non-acclimated stages. Survival increased by 17.5% for eggs, 40.0% and 13.3% for 3rd and 5th instar larvae, and by 20.0% for pupae after CA. Compared to controls, survival of eggs under the conditions of thermoperiod (5:15 °C), thermoperiod (5:15 °C) + RHH, and thermoperiod (5:15, 10:20, and 15:25 °C) + RCH significantly increased. In addition, survival of 3rd and 5th instar larvae and pupae increased under the conditions of thermoperiod (5:15 °C) and thermoperiod (5:15 °C) + RCH, possibly due to the induction of heat shock proteins or cryoprotectants. However, the pre-treatments of thermoperiod + RCH + RHH and thermoperiod + RHH + RCH did not significantly enhance survival of any developmental stage. These adaptive responses may allow S. exigua to enhance supercooling capacity and survival in response to seasonal or unexpected diurnal decreases in environmental temperatures.     

我国不同地区草地贪夜蛾内共生菌感染和耐寒能力差异研究

本研究旨在明确我国不同地区草地贪夜蛾Spodoptera frugiperda共生菌感染差异和耐寒能力差异。采用16S或23S rDNA等定性检测方法,鉴定草地贪夜蛾共生菌种类并测定其感染率,通过邻接法（Neighbor-joining）构建系统进化树,进行共生菌系统发育分析。从我国8个地区采集的草地贪夜蛾幼虫中鉴定出2种内共生细菌,分别为Arsenophonus和Cardinium。两种共生菌在不同地理种群中的感染率存在显著差异,其中Arsenophonus感染率总体较低,云南保山种群感染率最高,为20.0%,其次是广西南宁种群(15.5%),贵州贵阳和江苏盐城的种群感染率均为1.7%,而广东广州、江苏无锡以及湖北宜昌和孝感种群中均未发现Arsenophonus的感染;Cardinium感染以江苏无锡种群最高,达96.7%,云南保山和广东广州种群感染率分别为93.3%和86.7%,贵州贵阳种群为53.3%,湖北孝感和宜昌感染率则分别为30.0%和18.3%,江苏盐城种群感染率也为18.3%,而广西南宁种群中未发现该共生菌。对8个地区草地贪夜蛾的耐寒能力比较表明,江苏盐城和湖北孝感种群耐寒能力最弱,-6℃下死亡率分别为76%和69%,显著高于其它6个种群,后6个种群间无显著差异,死亡率在35%~49%之间。我国不同地区草地贪夜蛾在共生菌感染和耐寒能力上均存在差异,但未发现共生菌感染与耐寒能力的相关性。     

Two different strategies for light utilization in photosynthesis in relation to growth and cold acclimation

Seedlings of Lodgepole pine (Pinus contorta L.) and winter wheat (Triticum aestivum L. cv. Monopol) were cold acclimated under controlled conditions to induce frost hardiness. Lodgepole pine responded to cold acclimation by partial inhibition of photosynthesis with an associated partial loss of photosystem II reaction centres, and a reduction in needle chlorophyll content. This was accompanied by a low daily carbon gain, and the development of a high and sustained capacity for non‐photochemical quenching of absorbed light. This sustained dissipation of absorbed light as heat correlated with an increased de‐epoxidation of the xanthophyll cycle pigments forming the quenching forms antheraxanthin and zeaxanthin. In addition, the PsbS protein known to bind chlorophyll and the xanthophyll cycle pigments increased strongly during cold acclimation of pine. In contrast, winter wheat maintained high photosynthetic rates, showed no loss of chlorophyll content per leaf area, and exhibited a high daily carbon gain and a minimal non‐photochemical quenching after cold acclimation. In accordance, cold acclimation of wheat neither increased the de‐epoxidation of the xanthophylls nor the content of the PsbS protein. These different responses of photosynthesis to cold acclimation are correlated with pine, reducing its need for assimilates when entering dormancy associated with termination of primary growth, whereas winter wheat maintains a high need for assimilates as it continues to grow and develop throughout the cold‐acclimation period. It appears that without evolving a sustained ability for controlled dissipation of absorbed light as heat throughout the winter, winter green conifers would not have managed to adapt and establish themselves so successfully in the cold climatic zones of the northern hemisphere.     

Gender-specific cold responses induce a similar body-cooling rate but different neuroendocrine and immune responses

This study investigated whether there are any gender differences in body-heating strategies during cold stress and whether the immune and neuroendocrine responses to physiological stress differ between men and women. Thirty-two participants (18 men and 14 women) were exposed to acute cold stress by immersion to the manubrium level in 14 °C water. The cold stress continued until rectal temperature (T_RE) reached 35.5 °C or for a maximum of 170 min. The responses to cold stress of various indicators of body temperature, insulation, metabolism, shivering, stress, and endocrine and immune function were compared between men and women. During cold stress, T_RE and muscle and mean skin temperatures decreased in all subjects (P < 0.001). These variables and the T_RE cooling rate did not differ between men and women. The insulative response was greater in women (P < 0.05), whereas metabolic heat production and shivering were greater (P < 0.05) in men. Indicators of cold strain did not differ between men and women, but men exhibited larger changes in the indicators of neuroendocrine (epinephrine level) and in immune (tumor necrosis factor-α level) responses (both P < 0.05). The results of the present study indicated that men exhibited a greater metabolic response and shivering thermogenesis during acute cold stress, whereas women exhibited a greater insulative response. Despite the similar experience of cold strain in men and women, the neuroendocrine and immune responses were larger in men. Contrary to our expectations, the cooling rate was similar in men and women.     

Is female-biased sex determination in lemmings caused by staying together for warmth?

Two kinds of lemming have evolved genetic modifications of sex determination that result in surpluses of daughters. Female-biased sex ratios can evolve when mating occurs between neighbouring individuals who are more related than if mating occurred randomly. Two proposed sources of such 'viscous' gene flow in lemmings arc cyclical changes in population density and mosaic habitat. Alternatively, perhaps cold climate favours winter aggregation and inhibits the dispersal of winter-born offspring, which would Nature and mate with close relatives; dispersal and outbreeding would occur during the warm months. Thus the episodes of dispersal and inbreeding would be seasonal rather than density-dependent and the supposition of discontinuous habitat is obviated.     

高寒山区草本植物的保护酶系统及其在低温生长中的作用

研究了高寒山区几种草本植物在低温生长过程中植物叶中抗氧化酶、抗氧化物和膜脂过氧化产物的变化及其作用。结果表明,耐寒性差、生长期短的一年生植物微孔草MDA含量较低,保护酶活力也较低。耐寒性强、生长期长的苜蓿、垂穗披碱草、草地早熟禾、无芒雀4种多年生植物MDA含量较高,保护酶活力和抗氧化物含量也较高。其生长季平均MDA含量分别比微孔草高2．27倍、1．64倍、2．07倍和1．55倍,超氧化物歧化酶（SOD）活力分别比微孔草高16．7％、27．1％、46．2％和11．5％;地氧化氢酶（CAT）分别高51．5％、123．0％、25．3％和9．4％,类胡萝卜麦含量分别高126．5％、142．7％、138．4％和394．4％。当气温低于0℃后,微孔草死亡,完成生活史,以种子越冬,在生理上无明显抗冻特征。而此时多年生植物SOD活力趋于增强,仍能一定生长,至－5℃～10℃低温时地上部才枯死,其细胞具有较强的耐膜脂过氧化能力和抗氧化酶系统,对环境的快速反应可能是其在高寒山区低温生长的重要生理机理。     

寒地稻田不同灌溉模式下稻株生长与水分消耗利用

为揭示不同灌溉模式下水稻植株生长与水分消耗利用,通过蒸渗仪与田间小区结合的方法,以常规淹灌模式作为对比,研究了三种灌溉模式的水稻植株生长与水分消耗利用。试验结果表明：水稻植株体通过水分的自我调解来适应稻田生态系统变化,灌溉模式对水稻植株各器官的湿基含水率产生显著影响（P<0.05）,控制灌溉模式能够有效地延缓水稻生育后期的根系衰老;作为水分的载体,水稻植株干物质积累量直接影响水稻的耗水量,控制灌溉模式下稻田生态系统的水稻耗水量较间歇灌溉和常规淹灌都有大幅度的降低,而水分利用效率大幅度提高;控制灌溉模式可以通过生长补偿效应来增加后期干物质的积累,从而提高籽粒产量。根据各灌溉模式水稻的腾发量结合实际降雨量,来调控稻田灌溉水量,能够有效地维持SPAC稻田生态系统平衡,保证农业和生态系统的可持续发展。研究结果可为寒地黑土区稻田生态系统水分消耗利用研究提供理论依据和技术支撑。     

Adaptation of fungi,including yeasts,to cold environments

A wide range of cold environments exist, with an equally broad variety of fungi and yeasts that have adapted to such environments. These adaptations, which affect membranes, enzymes and other cellular components, such as radical scavenging molecules, display a great potential for exploitation in biotechnology. Alterations have been detected in membrane lipids, with an increase in fatty acid unsaturated bonds that enhance their fluidity. We report new data on the different phospholipid composition in membrane lipids in the same fungal species from both Antarctic and temperate regions. The decrease in temperature causes intracellular oxidative stress by inducing the generation of reactive oxygen species. We report the results of the first analysis of the non-enzymatic antioxidant response and phenolic compound production by an Antarctic strain of Geomyces pannorum. A survey on yeasts from the cryosphere is reported with a focus on their adaptation to a cold environment. Some studies have shown that the number of macrofungi in glacier forefronts rises as deglaciation increases. The survival success of many plants in such areas may be attributed to their mycorrhizal associations. We highlighted the macrofungal biodiversity of some Italian alpine habitats, in which we Inocybe microfastigiata, Laccaria montana and Lactarius salicis-herbaceae were recorded for the first time in Lombardy (Italy).     

Estimating and improving cold filter plugging points by blending biodiesels with different fatty acid contents

Biodiesels are alkyl esters produced by transesterification of higher fatty acids (aliphatic chains composed of 14 to 22 carbon units) from animal fats and/or vegetable oils. The cold filter plugging points (CFPP) of biodiesels are not only higher than that of petro-diesel, but they also differ from the melting point of the raw (unesterified) materials. In this study, we empirically derived equations that estimated the CFPP of a biodiesel based on its fatty acid content, using various biodiesel blends containing four methyl esters with different fatty acid compositions: soybean (SME), palm (PME), rapeseed (RME), and lard (LME). These blending ratio experiments yielded three equations that described the correlation between CFPP and fatty acid content: Y (CFPP, °C) = −3.1X (blending ratio) − 12.7 (PME/SME); Y = 2.2X − 10.7 (LME/SME); and Y = −4.0X − 13.0 (PME/RME). We also obtained the correlation between CFPP and total saturated fatty acid methyl ester content in the biodiesels: Y (CFPP, °C) = 0.449X (total saturated fatty acid methyl ester content, wt%) − 9.198. These empirical equations accurately predicted CFPP values of biodiesel compounds with known fatty acid compositions, facilitating the use of diverse biodiesels in industrial fields. The first two authors equally contributed to this work.     

Role of HSF activation for resistance to heat, cold and high-temperature knock-down

Regulation of heat shock proteins (Hsps) by the heat shock factor (HSF) and the importance of these proteins for resistance to heat stress is well documented. Less characterized is the importance of Hsps for cold stress resistance although Hsp70 is known to be induced following long-term cold exposure in Drosophila melanogaster. In this study, a temperature-sensitive HSF mutant line was used to investigate the role of HSF activation following heat hardening, rapid cold hardening (RCH) and long-term cold acclimation (LTCA) on heat and cold resistance, and this was correlated with Hsp70 expression. In addition, the effect of HSF activation on high-temperature knock-down resistance was evaluated. We found a significantly decreased HSF activation in the mutant line as compared to a corresponding control line following heat hardening, and this was correlated with decreased heat resistance of the mutant line. However, we did not find this difference in HSF activity to be important for resistance to cold stress or high-temperature knock-down. The findings indicate that induction of stress genes regulated by HSF, such as Hsps, although occurring following LTCA, are not of major importance for cold stress resistance and neither for RCH nor high-temperature knock-down resistance in D. melanogaster.