Cold Temperature

ABSTRACTCold shock and ethanol and puromycin stress responses in sporulatingBacillus subtiliscells have been investigated. We show that a total of 13 proteins are strongly induced after a short cold shock treatment of sporulating cells. The cold shock pretreatment affected the heat resistance of the spores formed subsequently, with spores heat killed at 85 or 90°C being more heat resistant than the control spores while they were more heat sensitive than controls that were heat treated at 95 or 100°C. However,B. subtilisspores with mutations in the main cold shock proteins, CspB, -C, and -D, did not display decreased heat resistance compared to controls, indicating that these proteins are not directly responsible for the increased heat resistance of the spores. The disappearance of the stress proteins later in sporulation suggests that they cannot be involved in repairing heat damage during spore germination and outgrowth but must alter spore structure in a way which increases or dec...

SummaryThe present study investigates the effect of different slow chilling curves on the storage of pacu (Piaractus mesopotamicus)embryos submitted to chilling at −8°C. Embryos at the blastopore closure stage were divided into two groups: G1 – embryos exposed to cryoprotectant solution containing methanol (10%) and sucrose (0.5 M), treated as follows: (T1) taken directly from room temperature to the refrigerator without being submitted to the curve; (T2) chilling curve of 0.5°C/min; and (T3) chilling curve of 1°C/min; and G2 – the cryoprotectant solution alone was submitted to these same temperatures, receiving the embryos only after temperature had decreased, corresponding to treatments T4, T5 and T6, respectively. Treatments were kept at −8°C for a period of 6 h. Embryo development was evaluated for each treatment, with six replicates in an entirely randomized design. Survival among embryos not submitted to refrigeration was 94.3 ± 8.05%. Percentage of total larvae (TL) and addle...

BackgroundIn healthy humans, analgesia to blunt pressure develops in the ipsilateral forehead during various forms of limb pain. The aim of the current study was to determine whether this analgesic response is induced by ultraviolet B radiation (UVB), which evokes signs of peripheral sensitization, or by high‐frequency electrical stimulation (HFS), which triggers signs of central sensitization.MethodsBefore and after HFS and UVB conditioning, sensitivity to heat and to blunt and sharp stimuli was assessed at and adjacent to the treated site in the forearm. In addition, sensitivity to blunt pressure was measured bilaterally in the forehead. The effect of ipsilateral versus contralateral temple cooling on electrically evoked pain in the forearm was then examined, to determine whether HFS or UVB conditioning altered inhibitory pain modulation.ResultsUVB conditioning triggered signs of peripheral sensitization, whereas HFS conditioning triggered signs of central sensitization. Important...

ContentsEgg yolk is a common component to sperm refrigeration for most of the deer species, the role of which is to protect sperm membranes against cold shock. In addition, there have been many studies of conservation of ejaculated semen from stags, but few have been reported for epididymal spermatozoa. This work was designed to investigate the combined effects of cooling rates (slow: 0.23°C/min vs rapid: 4.2°C/min) from room temperature to 5°C, and egg‐yolk concentration (0, 5 or 20%) in the extender on the survival of Iberian red deer epididymal spermatozoa refrigerated at 5°C. Heterospermic sperm samples were diluted to a final sperm concentration ∼400 × 106 sperm/ml with a Tris–citrate‐fructose (TCF)‐egg‐yolk diluent. Sperm quality was in vitro judged by microscopic assessments of individual sperm motility [sperm motility index (SMI)], and of plasma membrane (hypo‐osmotic swelling test) and acrosome (NAR) integrities. Our results first showed that the presence of egg yolk in the...

This study was carried out to determine effects of different durations (20, 40, 60 days and control) of cold stratification treatments on seed germination and to overcome dormancy in seeds of twelve different drought tolerant plants. The species used in this study were Arbutus andrachne L., Cistus creticus L., Colutea armena Bois. Huet., Cotinus coggygria Scop., Cotoneaster numullaria Fisch. and Mey, Elaeagnus angustifolia L., Jasminum fruticans L., Paliurus spina-christii Mill., Punica granatum L., Pyracantha coccinea Roem., Rhus coriaria L., and Ziziphus jujuba Mill. The seeds were sown in polyethylene pots under greenhouse and on seedbeds under open field conditions. Statistical design was a randomized complete block design with three replications. Germinated seeds were counted and observed periodically for 90 days after sowing to determine germination percentages (GP) and germination rates (GR). While the highest GP were determined according to duration of cold stratification un...

The effects of changes in shivering intensity on the relative contributions of plasma glucose, muscle glycogen, lipids and proteins to total heat production are unclear in humans. The goals of this study were: (1) to determine whether plasma glucose starts playing a more prominent role as shivering intensifies, (2) to quantify overall changes in fuel use in relation to the severity of cold exposure, and (3) to establish whether the fuel selection pattern of shivering is different from the classic fuel selection pattern of exercise. Using a combination of indirect calorimetry and stable isotope methodology, fuel metabolism was monitored in non‐acclimatized adult men exposed for 90 mins to 10°C (low‐intensity shivering (L)) or 5°C (moderate‐intensity shivering (M)). Results show that plasma glucose oxidation is strongly stimulated by moderate shivering (+122% from L to M), but the relative contribution of this pathway to total heat generation always remains minor (< 15% of total he...

Carbohydrates (CHO) can play an important thermogenic role during shivering, but the effect of their availability on the use of other oxidative fuels is unclear. Using indirect calorimetry and tracer methods ([U-13C]glucose ingestion), we have determined the specific contributions of plasma glucose, muscle glycogen, proteins, and lipids to total heat production (Ḣprod) in men exposed to cold for 2-h (liquid-conditioned suit perfused with 10°C water). Measurements were made after low-CHO diet and exercise (Lo) and high-CHO diet without exercise (Hi). The size of CHO reserves had no effect on Ḣprod but a major impact on fuel selection before and during shivering. In the cold, a complete shift from lipid oxidation for Lo (53, 28, and 19% Ḣprod for lipids, CHO, and proteins, respectively) to CHO-based metabolism for Hi (23, 65, and 12% Ḣprod for lipids, CHO, and proteins, respectively) was observed. Plasma glucose oxidation remains a minor fuel under all conditions (<13% Ḣprod), fall...

The yeast vacuole functions both as a degradative organelle and as a storage depot for small molecules and ions. Vacuoles are dynamic reticular structures that appear to alternately fuse and fragment as a function of growth stage and environment. Vac8p, an armadillo repeat-containing protein, has previously been shown to function both in vacuolar inheritance and in protein targeting from the cytoplasm to the vacuole. Both myristoylation and palmitoylation of Vac8p are required for its efficient localization to the vacuolar membrane (Y.-X. Wang, N. L. Catlett, and L. S. Weisman, J. Cell Biol. 140:1063–1074, 1998). We report that mutants with conditional defects in the rate-limiting enzyme of fatty acid synthesis, acetyl coenzyme A carboxylase ( ACC1 ), display unusually multilobed vacuoles, similar to those observed in vac8 mutant cells. This vacuolar phenotype of acc1 mutant cells was shown biochemically to be accompanied by a reduced acylation of Vac8p which was alleviated by fatty...

Background Analgesic effect of exercise is a well established fact; however available reports are contradictory on gender differences in pain perception following exercise stress test. Objective The current study is prospectively designed to evaluate and compare the effect of acute bout of sub-maximal exercise stress on cold pressor pain in normal adult males and females. Method The experimental study design involved healthy adults (n= 41); females (n = 18) and males (n=23) aged between 18 to 25 years and included them into four sets of experiments: SET I (Control), “resting blood pressure, radial pulse and respiratory rate were recorded after 15 minutes of complete supine relaxation. SET II (Cold Pressor Pain Test): Pain Threshold, Pain Tolerance, and Pain Duration in seconds were taken. SET III (Exercise Stress Test): Sub-maximal exercise of 70 to 75% of maximum predicted heart rate was given for 6 minutes. SET IV (Cold Pressor Pain Test immediately after Exercise Stress Test): At...

A hallmark of many orofacial pain disorders is cold sensitivity, but relative to heat-related pain, mechanisms of cold perception and the development of cold allodynia are not clearly understood. Molecular mediators of cold sensation such as TRPM8 have been recently identified and characterized using in vitro studies. In this study we characterized operant behavior with respect to individually presented cold stimuli (24, 10, 2, and -4 degrees C) and in a thermal preference task where rats chose between -4 and 48 degrees C stimulation. We also evaluated the effects of menthol, a TRPM8 agonist, on operant responses to cold stimulation (24, 10, and -4 degrees C). Male and female rats were trained to drink sweetened milk while pressing their shaved faces against a thermode. This presents a conflict paradigm between milk reward and thermal stimulation. We demonstrated that the cold stimulus response function was modest compared to heat. There was a significant effect of temperature on fa...