Thalassomyxa australis rhythmicity II. No entrainment by light‐dark‐cycles and temperature cycles?

Abstract

The rhythmic change between an active phase and a resting phase of the plasmodial rhizopod Thalassomyxa australis sustained on the diatome Amphiprora, is not synchronized by a 12: 12 h light‐dark‐cycle. Likewise, 12: 12 h temperature cycles of 8°C difference such as 23°/15°C, 25°/17°C, 27°/19°C are not entraining this rhythm.     

Effects of Menstrual Cycle and Room Temperature on Color Preference

This study investigated the effects of menstrual cycle on color preference in nine normally menstruating female subjects. They were instructed to choose their preferred color out of 45 Munsell hues every 5 min at ambient temperatures (T _a) of 28°C (630-800 h), from 28°C to 23°C (800-900 h) and at 23°C (900-930 h). Warmer color hues were preferred during the luteal phase than the follicular phase at 28°C, while there did not exist any significant differences at other T _as. The findings that a preference for warmer colors occurred in the luteal phase at 28°C is discussed in terms of the load error between actual core temperature and its setpoint.     

Phase resetting of the circadian rhythm of carbon dioxide assimilation inBryophyllum leaves in relation to their malate content following brief exposure to high and low temperatures,darkness and 5% carbon dioxide

Leaves ofBryophyllum fedtschenkoi show a persistent circadian rhythm in CO₂ assimilation when kept in continuous illumination and normal air at 15°C. The induction of phase shifts in this rhythm by exposing the leaves for four hours at different times in the circadian cycle to 40° C, 2° C, darkness and 5% CO₂ have been investigated. Exposure to high temperature has no effect on the phase at the apex of the peak but is effective at all other times in the cycle, whereas exposure to low temperature, darkness or 5% CO₂ is without effect between the peaks and induces a phase shift at all other times. The next peak of the rhythm occurs 17 h after a 40° C treatment and 7–10 h after a 2° C, dark or 5% CO₂ treatment regardless of their position in the cycle. When these treatments are given at times in the cycle when they induce maximum phase shifts, they cause no change in the gross malate status of the leaf. The gross malate content of the leaf in continuous light and normal air at 15% shows a heavily damped circadian oscillation which virtually disappears by the time of the third cycle, but the CO₂ assimilation rhythm persists for many days. The generation of the rhythm, and the control of its phase by environmental factors are discussed in terms of mechanisms that involve the synthesis and metabolism of malate in specific localised pools in the cytoplasm of the leaf cells.     

Screening Escherichia coli, Enterococcus faecalis, and Clostridium perfringens as Indicator Organisms in Evaluating Pathogen-Reducing Capacity in Biogas Plants

This study was conducted to identify an indicator organism(s) in evaluating the pathogen-reducing capacity of biogas plants. Fresh cow manure containing 10⁴ to 10⁵ colony forming unit (CFU) per milliliter of Escherichia coli and Enterococcus faecalis along with an inoculated Clostridium perfringens strain were exposed to 37°C for 15 days, 55°C for 48 h, and 70°C for 24 h. C. perfringens was the most heat-resistant organism followed by E. faecalis, while E. coli was the most heat-sensitive organism. E. coli was reduced below detection limit at all temperatures with log₁₀ reductions of 4.94 (10 s), 4.37 (40 min), and 2.6 (5 days) at 70°C, 55°C, and 37°C, respectively. Maximum log₁₀ reductions for E. faecalis were 1.77 at 70°C (1 day), 1.7 at 55°C (2 days) and 3.13 at 37°C (15 days). For C. perfringens, maximum log₁₀ reduction at 37°C was 1.35 log₁₀ units (15 days) compared to less than 1 unit at 55 and 70°C. Modeling results showed that E. faecalis and C. perfringens had higher amount of heat-resistant fraction than E. coli. Thus, E. faecalis and C. perfringens can be used as indicator organisms to evaluate pathogen-reducing capacity in biogas plants at high temperatures of 55°C and 70°C while at 37°C E. coli could also be included as indicator organism.     

Effects of environmental factors on growth of lesions on field bean leaves infected by Botrytis fabae

Chocolate spot lesions increased in size only slowly when the relative humidity of the air was below 66%. Following a lag phase immediately after infection the rate of increase was linear and proportional to humidity between c. 70% and 100% r.h. Lesions on leaflets kept at 70% r.h. for 8 h and at 100% r.h. for 16 h/day increased in size at only 27% of the rate of those at continuous 100% r.h. The optimum temperature for lesion growth was between 15 and 22 °C, the minimum <4 °C and the maximum c. 30 °C. Humidity did not interact with temperature between 10 and 20 °C. Neither light intensity nor a film of water over the leaves affected lesion growth. These findings are discussed in relation to meteorological data and field observations. The possible mechanisms whereby humidity affects lesion growth did not appear to be related to CO₂ and O₂ concentrations nor to the overall water potential of the leaf. Preliminary evidence is presented for the production of phytotoxins within lesions.     

Bioaccumulation of Gold by Filamentous Cyanobacteria Between 25 and 200°C

Plectonema boryanum UTEX 485 was reacted with aqueous AuCl ₄ ^? solutions ( ～ 2 mM Au) at 25 to 100°C for 1 month, and 200°C for one day. Addition of AuCl₄ ^? to cyanobacteria killed the cultures instantly, and Au was precipitated throughout the cells as nanoparticles. Precipitation of octahedral crystal platelets of Au occurred in the aqueous fluid, with particle size increasing with increase in temperature from about 1.5 μ m at 25°C to 10 μ m at 100°C. Addition of AuCl₄ ^? to suspensions of the dead, autoclaved cyanobacteria also precipitated Au from solution, suggesting that the presence of cell degradation products caused instability of AuCl₄ ^? .     

Optimized 4‐V Spinel Cathode Material with High Energy Density for Li‐Ion Cells Operating at 60 °C

Spinel cathodes comprising 16‐μm, AlPO₄‐coated Li_1.09Mn_1.83Al_0.08O₄ with a high energy density of 1.2 W h cm^‐3 are synthesized via a conventional solid‐state reaction using MnO₂ and Li₂CO₃ at 770 °C for 10 h and using a solution‐based coating method in bulk scale (>20 kg). The cathodes are coated by aluminum phosphate at a thickness of <10 nm. The coated cathodes exhibit a first discharge capacity of 108 mA·h g^‐1 and a coulombic efficiency of >99.8%, and their capacity retention is 78% after 200 cycles at a 0.5C rate in a Li‐ion cell under 60 °C. More importantly, a Li‐ion cell containing the coated cathode does not exhibit a swelling problem after 200 cycles at 60 °C. Transmission and scanning electron microscopy suggest that the uniformly distributed AlPO₄ coating and the possible formation of a solid solution phase along the surface play key roles in enhancing the electrochemical performance of the LiMn₂O₄ spinel at 60 °C.     

Ghrelin Induces Time-Dependent Modulation of Thermoregulation in the Cold

Fasted mice show torpor-like hypothermia in the cold in their inactive phase. The aim of the present study was to elucidate whether leptin and/or ghrelin are involved in this reaction and to identify its neurophysiological mechanisms. In ob/ob mice, which lack leptin, metabolic heat production (oxygen consumption, Vo₂) was suppressed in 20°C cold in both the light and dark phases, resulting in hypothermia. When wild-type mice received a systemic injection of 8?µg ghrelin in the early light phase, followed by a 2-h cold exposure to 10°C, their core body temperature (T_b) decreased by 1.7°C, and they displayed a less marked increase in Vo₂ compared with vehicle-injected mice. However, ghrelin injection in the early dark phase resulted in the maintenance of T_b and increased Vo₂ in the mice, which was similar to the result observed in the vehicle-injected mice. The number of doubly labeled neurons with cFos and neuropeptide Y (NPY) in the suprachiasmatic nucleus was greater in the light phase in the ghrelin-injected mice, which may suggest that ghrelin activates NPY neurons. On the contrary, in the paraventricular nucleus, the counts became greater only when they were exposed to the cold in the dark phase. These results indicate that ghrelin plays an important role in inducing time-dependent changes in thermoregulation in the cold via hypothalamic pathways. (Author correspondence: tokizawa@aoni.waseda.jp)     

Thermolabile Liposomes with a High Fusion Efficacy at 42°C can be Made of Dipalmitoylphosphatidylcholine/Fatty Alcohol Mixtures in the Molar Ratio of 1/2

Abstract

Liposomes made of dipalmitoylphosphatidylcholine (DPPC²), dipalmitoyl-phosphatidylglycerol (DPPG), and different long-chain fatty alcohols were investigated with respect to their colloidal stability, chain-melting phase transition temperature, and temperature dependent inter-vesicle fusion. In particular, the practical usefulness of the stoichiometric 1/2 (mol/mol) mixtures of the phospholipids and fatty alcohols, mainly elaidoyl alcohol (EL-OH) were studied. The mole fraction of DPPG in the bilayers of such vesicles affects crucially the colloidal stability of the resulting lipid suspensions; at least 15 mol-% of DPPG (relative to DPPC) must be incorporated into the bilayers in order to make the liposome suspension colloidally sufficiently stable at room temperature. The corresponding DPPC/DPPG/EL-OH (0.85/0.15/2) mixed lipid vesicles undergo a lamellar-gel to inverted hexagonal (H_IT) phase transition at 52.7°C, however, and then fuse and aggregate massively. The related phase transition temperature of the DPPC/DPPG/palmitelaidoyl alcohol (0.85/0.15/2) mixture is 48.4°C. This indicates that the chain-melting phase transition temperature of the investigated lipid mixtures is rather sensitive to the alcohol chain-length. This transition temperature is independent, however, of the bulk proton concentration in the pH region between 4.9 and 7.2. Stoichiometric 1/2 mixtures of phospholipids and EL-OH have a high propensity for the inter-vesicle fusion at 42°C and neutral pH. The reason for such fusion 10°C below the lamellar-to-nonlamellar phase transition temperature are the defects that are generated during the chain-melting of the (partly segregated) phospholipid component at 42°C; the proximity of the lamellar to non-lamellar phase transition temperature of the phospholipid/fatty alcohol (1/2) complex at 52°C also plays an important role.     

Effects of microhabitat,light and temperature on seed germination of a critically endangered Himalayan medicinal herb,Swertia chirayita: Conservation implications

Abstract

Swertia chirayita, a critically endangered medicinal herb, is being over-harvested in the wild. Understanding seed germination is a pre-requisite to ensure species conservation. The germination of seeds collected from six microhabitats was studied at 20°C, 25°C, and 30°C, both under a 14/10 h light/dark photoperiod and in continuous darkness. Two-way ANOVA indicated that microhabitat and temperature significantly affect seed germination, germination rate, germination recovery (GR), and GR rate. Overall, the seeds collected from under canopy showed a significantly (p < 0.05) higher germination than those from open habitats, at 20°C, 25°C, and 30°C (14/10 h light/dark photoperiod). Germination was negligible in continuous darkness but after transfer to a 14/10 h light/dark photoperiod, the seeds from under canopy significantly recovered at 20°C and at 25°C (p < 0.05), and showed the highest germination percentage compared to seeds collected from tree base, stump base, shrubberies, and grassy slope. Similarly, at 30°C, seeds from under canopy recorded the highest GR percentage. In general, seed germination, mean germination rate, seed GR, and GR rate were significantly greater (p < 0.05) at 25°C. Among the microhabitats tested, variation in GR rate was significant (p < 0.05). Seeds were confirmed to be positively photoblastic.     

A Novel Phospholipase C Inhibitor,S-PLI Produced by Streptomyces Sp. Strain No. A-6288

Abstract

S-PLI, an inhibitor of phospholipase C (PLC) produced by Strepromyces sp. strain No. 6288, was purified from the culture filtrate by salting-out with solid ammonium sulfate, column chromatography on CM-cellulose and gel filtration on Sephadex G-75. The molecular weight of S-PLI was estimated to be 65,000 by SDS-polyacrylamide gel electrophoresis. The inhibitor was found to be a glycoprotein with a composition of 609 amino acids and 19 glucose residues having an isoelectric point at 7.8. S-PLI was stable from pH 3 to 10 at 37°C and up to 40° at pH 6.0. The inhibitory activity showed pH-and temperature-dependence with a maximum around pH 7.0 at 50°C. S-PLI inhibited phospholipase C in a competitive manner (K_i value; 9.5 × 10-⁶ mM), but did not inhibit S-Hemolysin, phospholipase A₂, phospholipase B, phospholipase D and phosphatases. S-PLI is the first reported example of a glycoproteinaceous inhibitor of microbial origin which is able to specifically inhibit phospholipase C.     

Production and characterization of a cold-active and n-hexane activated lipase from a newly isolated Serratia grimesii RB06-22

Abstract

A lipase-producing bacterium isolated from raw milk was identified as Serratia grimesii based on 16S rRNA sequence analysis. The extracellular lipase was partially purified by ammonium sulfate precipitation and ultrafiltration. Maximal activity was observed at 10°C, the optimum pH was 8.0 and the enzyme was stable at 5–30°C for 1 h. The K_m and V_max values were 1.7 mM and 0.3 mM/min respectively. It was found that the lipase had the highest hydrolytic activity towards sunflower oil and soybean oil. CaCl₂ had a stimulatory effect on lipase activity, while EDTA and iodoacetic acid slightly inhibited the lipase activity and the enzyme was strongly inhibited by PMSF. The enzyme was compatible with various non-ionic surfactants as well as sodium cholate and saponin. In addition, the enzyme was relatively stable towards oxidizing agents. This lipase exhibited maximum activity in 35% n-hexane retaining about 2191% activity for 1 h.     

Purification and characterization of a serine alkaline protease from Bacillus clausii GMBAE 42

An extracellular serine alkaline protease of Bacillus clausii GMBAE 42 was produced in protein-rich medium in shake-flask cultures for 3 days at pH 10.5 and 37°C. Highest alkaline protease activity was observed in the late stationary phase of cell cultivation. The enzyme was purified 16-fold from culture filtrate by DEAE-cellulose chromatography followed by (NH₄)₂SO₄ precipitation, with a yield of 58%. SDS-PAGE analysis revealed the molecular weight of the enzyme to be 26.50 kDa. The optimum temperature for enzyme activity was 60°C; however, it is shifted to 70°C after addition of 5 mM Ca²⁺ ions. The enzyme was stable between 30 and 40°C for 2 h at pH 10.5; only 14% activity loss was observed at 50°C. The optimal pH of the enzyme was 11.3. The enzyme was also stable in the pH 9.0–12.2 range for 24 h at 30°C; however, activity losses of 38% and 76% were observed at pH values of 12.7 and 13.0, respectively. The activation energy of Hammarsten casein hydrolysis by the purified enzyme was 10.59 kcal mol⁻¹ (44.30 kJ mol⁻¹). The enzyme was stable in the presence of the 1% (w/v) Tween-20, Tween-40,Tween-60, Tween-80, and 0.2% (w/v) SDS for 1 h at 30°C and pH 10.5. Only 10% activity loss was observed with 1% sodium perborate under the same conditions. The enzyme was not inhibited by iodoacetate, ethylacetimidate, phenylglyoxal, iodoacetimidate, n-ethylmaleimidate, n-bromosuccinimide, diethylpyrocarbonate or n-ethyl-5-phenyl-iso-xazolium-3′-sulfonate. Its complete inhibition by phenylmethanesulfonylfluoride and relatively high k _cat value for N-Suc-Ala-Ala-Pro-Phe-pNA hydrolysis indicates that the enzyme is a chymotrypsin-like serine protease. K _m and k _cat values were estimated at 0.655 μM N-Suc-Ala-Ala-Pro-Phe-pNA and 4.21×10³ min⁻¹, respectively.     

Expression of heat shock proteins in response to high and low temperature extremes in diapausing pharate larvae of the gypsy moth,Lymantria dispar

Diapausing pharate first instars of the gypsy moth, Lymantria dispar, respond to high temperature (37–41°C) by suppressing normal protein synthesis and synthesizing a set of seven heat shock proteins with M_rs of 90,000, 75,000, 73,000, 60,000, 42,000, 29,000, and 22,000 as determined by SDS-PAGE. During recovery at 25°C from heat shock, synthesis of the heat shock proteins gradually decreases over a period of 6 h, while normal protein synthesis is restored. A subset of these same heat shock proteins is also expressed during recovery at 4°C or 25°C from brief exposures to low temperature (-10 to 20°C), and its expression is more intense with increased severity of cold exposure. During recovery at 4°C after 24 h at ?20°C, both 90,000 and 75,000 M_r heat shock proteins are expressed for more than 96 h. While normal protein synthesis is suppressed during heat shock and recovery from heat shock, normal protein synthesis coincides with synthesis of the heat shock proteins during recovery from low temperatures, thus implying that expression of the heat shock proteins is not invariably linked to suppression of normal protein synthesis. Western transfer, using a monoclonal antibody that recognizes the inducible form of the human 70,000 M_r heat shock protein, demonstrates that immunologically related proteins in the gypsy moth are expressed at 4°C and during recovery from cold and heat shock.     

Engineered thermostable fungal Cel6A and Cel7A cellobiohydrolases hydrolyze cellulose efficiently at elevated temperatures

Thermostability is an important feature in industrial enzymes: it increases biocatalyst lifetime and enables reactions at higher temperatures, where faster rates and other advantages ultimately reduce the cost of biocatalysis. Here we report the thermostabilization of a chimeric fungal family 6 cellobiohydrolase (HJPlus) by directed evolution using random mutagenesis and recombination of beneficial mutations. Thermostable variant 3C6P has a half‐life of 280 min at 75°C and a T₅₀ of 80.1°C, a ～15°C increase over the thermostable Cel6A from Humicola insolens (HiCel6A) and a ～20°C increase over that from Hypocrea jecorina (HjCel6A). Most of the mutations also stabilize the less‐stable HjCel6A, the wild‐type Cel6A closest in sequence to 3C6P. During a 60‐h Avicel hydrolysis, 3C6P released 2.4 times more cellobiose equivalents at its optimum temperature (T_opt) of 75°C than HiCel6A at its T_opt of 60°C. The total cellobiose equivalents released by HiCel6A at 60°C after 60 h is equivalent to the total released by 3C6P at 75°C after ～6 h, a 10‐fold reduction in hydrolysis time. A binary mixture of thermostable Cel6A and Cel7A hydrolyzes Avicel synergistically and released 1.8 times more cellobiose equivalents than the wild‐type mixture, both mixtures assessed at their respective T_opt. Crystal structures of HJPlus and 3C6P, determined at 1.5 and 1.2 Å resolution, indicate that the stabilization comes from improved hydrophobic interactions and restricted loop conformations by introduced proline residues. Biotechnol. Bioeng. 2013; 110: 1874–1883. © 2013 Wiley Periodicals, Inc.     

The role of temperature in enhancing the insecticidal activity of Bacillus thuringiensis against Spodoptera littoralis larvae

The present study scrutinised how far temperature would affect the velocity of the insecticidal activity of Bacillus thuringiensis, as the rapidity of pest control achievements is of a great concern. Third instar Spodoptera littoralis larvae were treated with Bt at three concentration levels under five different temperatures (15°C, 20°C, 25°C, 30°C and 35°C). LT₅₀s were evaluated in each case. The LT₅₀ values showed various levels of reductions as temperature and/or Bt concentration increased, indicating that the velocity of mortality (1/LT₅₀) and/or the rapidity of Bt activity was almost temperature dependant. However, relatively high and low reduction percentages in the LT₅₀ values on the elevation of 5°C were obtained at lower and higher temperature ranges, respectively. The temperature coefficient, Q ₁₀ values, determined within narrow ranges (5°C) showed great reductions when temperature increased from 15°C to 20°C at all Bt concentrations. Raising temperature by 5°C above 20°C or 25°C almost caused similar Q ₁₀ values indicating constant increase in the response of Bt activity within 20–30°C temperature range. Q ₁₀ values over 30°C were comparatively very low. This proved that decrease in Q ₁₀ values due to the rise of temperature was dependant on the starting temperature.     

Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum

This paper aims to determine the changes in reactive oxygen species (ROS) and the responses of the lily (Lilium longiflorum L.) antioxidant system to short-term high temperatures. Plants were exposed to three levels of heat stress (37°C, 42°C, 47°C) for 10 h when hydrogen peroxide (H₂O₂) and superoxide (O₂⁻) production rate along with membrane injury indexes, and changes in antioxidants were measured. Compared with the control (20°C), electrolyte leakage and MDA concentration varied slightly after 10 h at 37°C and 42°C, while increased significantly at 47°C. During 10 h at 37°C and 42°C, antioxidant enzyme activities, such as SOD, POD, CAT, APX and GR, were stimulated and antioxidants (AsA and GSH concentrations) maintained high levels, which resulted in low levels of O₂⁻ and H₂O₂ concentration. However, after 10 h at 47°C, SOD, APX, GR activities and GSH concentration were similar to the controls, while POD, CAT activities and AsA concentration decreased significantly as compared with the control, concomitant with significant increase in O₂⁻ and H₂O₂ concentrations. In addition, such heat-induced effects on antioxidant enzymes were also confirmed by SOD and POD isoform, as Cu/ZnSOD maintained high stability under heat stress and the intensity of POD isoforms reduced with the duration of heat stress, especially at 47°C. It is concluded that in lily plants, the oxidative damage induced by heat stress was related to the changes in antioxidant enzyme activities and antioxidants.     

Using temperature and time criteria to control the effectiveness of continuous thermal sanitation of piggery effluent in terms of set microbial indicators

Aim: To determine the minimal conditions (temperature–time), necessary to achieve set sanitation targets for selected microbial indicators during the continuous thermal treatment of pig slurry. Methods and Results: The effectiveness of thermal treatment between 55 and 96°C was studied using Escherichia coli, enterococci, sulfite‐reducing Clostridia (SRC), mesophilic culturable bacteria (MCB), F+‐specific and somatic phages. Identification of SRC and MCB was performed using 16S rRNA gene analysis. Ten minutes at 70°C or 1 h at 60°C was sufficient to reduce the vegetative bacteria by 4–5 log₁₀, but it had little effect on somatic phages nor on spore formers, dominated by Clostridium sp. At 96°C, somatic phages were still detected, but there was a reduction of 3·1 log₁₀ for SRC and of 1·4 log₁₀ for MCB. At 96°C, Clostridium botulinum was identified among the thermotolerant MCB. Conclusion: Only those hygienic risks relating to mesophilic vegetative bacteria can be totally eliminated from pig slurry treated at 60°C (60 min) or 70°C (<10 min). Significance and Impact of the Study: Hygiene standards based on the removal of the indicators E. coli and enterococci can easily be met by treatment as low as 60°C (enabling, a low‐cost treatment using heat recovery). However, even at 96°C, certain pathogens may persist.     

The importance of fluctuating thermal regimes for repairing chill injuries in the tropical beetle Alphitobius diaperinus (Coleoptera: Tenebrionidae) during exposure to low temperature

Abstract. In this study, the impact of acclimation (1 month at 15 °C vs. breeding at 30 °C) and fluctuating thermal regimes (daily transfers from low temperatures to various higher temperatures for 2 h) on the cold tolerance of the tropical beetle, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae) was examined. Acclimation increased significantly the duration of survival (Lt₅₀) at a constant 5 °C (7.7 ± 0.3 days to 9.7 ± 0.5 days). Survival of acclimated and nonacclimated beetles increased slightly at alternating temperatures of 5 °C/10 °C or 5 °C/15 °C. When daily transfer to 20 °C was applied, survival (Lt₅₀) was improved markedly (nonacclimated: 15.5 ± 0.7 days, acclimated: 19.6 ± 0.6 days). The higher temperatures may allow progressive repair of injuries, and the effects of chilling may be repaired completely at 25 and 30 °C, a phenomenon recorded here for the first time. It is estimated that the theoretical upper threshold of chill injury (Th) of nonacclimated beetles is 15.1 °C whereas it is shifted down to 11.2 °C in acclimated beetles, which might enable this temperature to allow effective repair of injury.