Miscibility studies of HPMC/PVA blends in water by viscosity, density, refractive index and ultrasonic velocity method

Hydroxy propyl methyl cellulose (HPMC)/polyvinyl alcohol (PVA) blends are edible polymer films used for food packing and directly in foodstuffs. However they are water-soluble in ordinary temperature and have good mechanical properties. The miscibility of HPMC/PVA blend in water was studied by viscosity, ultrasonic velocity, density and refractive index techniques at 30 and 50 °C. Using viscosity data, the interaction parameters μ and α were calculated. These values revealed that HPMC/PVA blend is miscible when the HPMC content is more than 60% in the blend at 30 and 50 °C. And also the result revealed that the change in temperature has no significant effect on the miscibility of HPMC/PVA polymer blend.     

Synthesis of thermo-sensitive polyacrylamide derivatives for affinity precipitation and its application in purification of lysozyme

The thermo-sensitive N-alkyl substituted polyacrylamide polymer was synthesized by radical polymerization and its lower critical solution temperature (LCST) was controlled to be 28 °C. The thermo-sensitive recovery of polymer was over 95% in the presence of 0.05 M NaClO₄. Cibacron Blue F3GA was covalently immobilized onto the polymer via the nucleophilic reaction between the active chlorine atom of its triazine ring and the hydroxyl group of the polymer. The ligands density was 30 μmol g⁻¹ polymer. The adsorption capacity of lysozyme on the polymer was 3.4 mg g⁻¹polymer in affinity precipitation process. And over 90% of adsorbed lysozyme was eluted by 0.5 M KSCN at pH 8.0. When the affinity polymer was applied in the purification of lysozyme from egg white, the purification factor was 28 and lysozyme yield was 80% or so.     

Synthesis of thermo-sensitive copolymer with affinity butyl ligand and its application in lipase purification

In this study, thermo-sensitive N-alkyl substituted polyacrylamide polymer P_NNB was synthesized by using N-hydroxymethyl acrylamide(NHAM), N-isopropyl acrylamide (NIPA) and butyl acrylate (BA) as monomers, and its low critical solution temperature (LCST) was controlled to be 28 °C. The recovery of the thermo-sensitive polymer was over 98%. Butanol as a hydrophobic ligand was covalently attached onto polymer P_NNB and butyl ligand density was 80 μmol g^?1 polymer. The affinity polymer was used for purification of lipase from crude material. Optimized condition was pH 7.0, 35 °C adsorption temperature, 120 min adsorption time and 0.5 mg ml^?1 initial concentration of lipase. The adsorption isotherm accords with a typical Langmuir isotherm. The maximum adsorption capacity (Q_m) of the affinity polymer for lipase was 24.8 mg g^?1polymer. The affinity copolymer could be recycled by temperature-inducing precipitation and there was only about 6% loss of adsorption capacity after five recyclings. Specific activity of lipase was improved from 14 IU mg^?1 to 506 IU mg^?1 protein, and its recovery achieved 82%. The affinity polymer is suitable for the purification of target proteins from the crude material with large volume and dilute solution.     

Preparation and characterization of cellulose/chitosan blend films

Cellulose and chitosan were mixed in N-methylmorpholine-N-oxide (NMMO) and heated to 100 °C, and then were processed under a pressure of 70 kg/cm² exerted by a compression molding machine at 100 °C for 8 min. As a result, transparent orange viscose films were obtained. After rinsing with deionized water and drying transparent yellowish blend films were obtained. Scanning electron microscope (SEM) indicated that when the chitosan content in the blend increased up to 3% the surface structure became smoother, but the film containing 5% (w/w) chitosan, became coarse again probably due to phase separation. Tensile strength test results were consistant with this. Antibacterial assessment proved that addition of chitosan to the films results in slight antibacterial properties. The halo zone test confirmed that the blend films made in this research have non-diffusible antibacterial properties.     

Effects of PEGylated porcine glucagon-like peptide-2 therapy in weaning piglets challenged with lipopolysaccharide

This study aims to evaluate the therapeutic effect of polyethylene glycosylated porcine glucagon-like peptide-2 (pGLP-2), a long-acting form of pGLP-2, in lipopolysaccharide (LPS)-challenged piglets. Eighteen 21-day-old weaning piglets were randomly assigned into three groups: control (saline solution), LPS (100 μg/kg LPS), and PEG–pGLP-2 (10 nmol/kg PEG–pGLP-2 + 100 μg/kg LPS). All treatments were administered intraperitoneally. Compared with the control treatment, LPS treatment significantly decreased (P < 0.05) the villus heights of the duodenum and jejunum, as well as the villus height/crypt depth ratio of the jejunum. However, PEG–pGLP-2 therapy reduced these effects (P > 0.05). Specifically, PEG–pGLP-2 infusion significantly increased the villus height/crypt depth ratio of the duodenum (P < 0.05) compared with LPS treatment. Compared with the control treatment, LPS treatment significantly increased (P < 0.05) the mRNA expression levels of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in the jejunum. However, PEG–pGLP-2 therapy reduced these effects (P < 0.05). Specifically, PEG–pGLP-2 infusion significantly decreased (P < 0.05) the mRNA expression levels of interleukin (IL)-8 and TNF-α in the duodenum and jejunum, IL-10 in the duodenum, and IFN-γ in the jejunum compared with the LPS treatment. LPS treatment increased the caspase-3 activity of the ileum mucosal (P < 0.05), and this effect was significantly reduced by PEG–pGLP-2 treatment. These results indicate that PEG–pGLP-2 infusion alleviates the severity of intestinal injury in weaning piglets by reducing the secretion of inflammatory cytokines and the caspase-3 activity, and increasing the villus height/crypt depth ratio.     

Decay and termite resistance,water absorption and swelling of thermally compressed wood panels

This study evaluated decay and termite resistance of thermally compressed pine wood panels under pressure at either 5 or 7 MPa and either 120 or 150 °C for 1 h. Wood specimens from the panels were exposed to laboratory decay resistance tests by using the wood degrading fungi, Gloeophyllum trabeum and Trametes versicolor. The thermal compression process caused increases in density and decreases in thickness of the panels; however, laboratory decay resistance tests revealed that thermally compressed wood was not resistant against the wood degrading fungi tested. More interesting results were found in laboratory termite resistance tests by using the Eastern subterranean termites, Reticulitermes flavipes. As pressure and temperature applied to the specimens increased to 7 MPa and 120 °C, mass losses in the specimens gradually decreased in comparison with control specimens. However, the specimens compressed at 7 MPa and 150 °C showed higher mass losses when compared to the specimens compressed at 7 MPa and 120 °C. The lowest water absorption and swelling rates were seen in the specimens exposed to a pressure of 7 MPa at 120 °C. The thermal compression process at 7 MPa and 150 °C resulted in the highest water absorption and swelling in the specimens.     

A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Effects of constant temperature,exposure period,and age on diapause induction in Trichogramma dendrolimi

Trichogramma dendrolimi can be successfully reproduced in fresh eggs dissected from ovaries of the Chinese tussah silkworm (Antheraea pernyi) and is widely used in biological control of lepidopteran agricultural and forest pests in China. Diapause induction of T. dendrolimi in A. pernyi eggs was investigated through exposing the parasitoid to six constant temperatures (16, 13, 10, 7, 4, and 1 °C) for 19 exposure periods between 10 and 46 days. The sensitive age of T. dendrolimi for diapause induction was explored through a separate experiment to examine the parasitoids that had developed for 2, 3, 4, 5, 6, 7, and 8 days at 26 °C after parasitization, under the six constant temperatures, respectively. Diapause was induced at 10 or 7 °C, and the induction period was 4–6 weeks. The sensitive age of T. dendrolimi to react at the induction temperature was 2–3 days (at 26 °C). At 7 and 10 °C, the diapause rate increased with increasing exposure period and decreased with increased T. dendrolimi age at exposure. The optimum method to induce diapause in T. dendrolimi consisted of exposing hosts for parasitization at 26 °C for 8 h, and then keeping them at 26 °C for 40 h, finally, moving them into 10 °C for 4 weeks.     

Effect of initial freezing temperature on the semen characteristics of frozen-thawed ram spermatozoa in a semi-arid tropical environment

Ram spermatozoa are sensitive to extreme changes in temperature during the freeze-thaw process. The degree of damage depends on a combined effect of various factors including initial freezing temperature. The present study was conducted to observe the effect of initial freezing temperature on post-thawing motility of ram spermatozoa of native and crossbred rams maintained in a semi-arid tropical environment. Good quality semen obtained from native Malpura and crossbred Bharat Merino rams were pooled within breed and diluted at a rate of 1000 million spermatozoa per milliliter in TEST—yolk–glycerol extender. Diluted semen samples were loaded in 0.25 ml straws and cooled to −25, −75 or −125 °C freezing temperature at the rate of −25 °C/min under controlled conditions before plunging into liquid nitrogen for storage. The thawing of straws was performed at 50 °C in a water bath for 10 s and motility characteristics of the frozen-thawed spermatozoa were assessed by a computer-assisted spermatozoa analysis technique. Initial freezing temperature significantly affected the post-thawing motility of sperm in both the breeds. The post-thawing % motility and rapid motile spermatozoa were significantly higher at initial freezing temperature of −125 °C and lower at −25 or −75 °C. The percentage medium motile sperm were similar at all three initial freezing temperatures. The percentage of slow motile and linearity of sperm varied (P<0.01) between the different freezing temperatures. The curvilinear velocity, average path velocity and straight line velocity of spermatozoa were higher (P<0.01) at −125 °C than −25 or −75 °C. Although the lateral head displacement of spermatozoa did not vary significantly between the different initial freezing temperatures, the stroke frequency was significantly lower at −25 °C than −75 or −125 °C. Except for % linearity, the average path velocity and straight line velocity, other spermatozoa characteristics were not significantly different between breeds. The interaction between freezing temperature and breed was significant only for the % motility and linearity of the spermatozoa. The study indicates that initial freezing temperature has a significant effect on spermatozoa motility and velocity following post-thawing. The best motile spermatozoa following thawing were achieved at −125 °C freezing temperature.     

Cryopreservation of sperm from seven-band grouper,Epinephelus septemfasciatus

In the present study, we examined methods for the cryopreservation of Epinephelus septemfasciatus spermatozoa. The percent motility, average path velocity, and linearity of movement (LIN) of fresh and corresponding post-thaw sperm were evaluated. Sperm motility was investigated using computer-assisted sperm analysis. Five percent dimethyl sulphoxide (Me₂SO) with 95% fetal bovine serum (FBS) was the most successful cryoprotectant diluent with a comparative post-thaw motility of 77.6 ± 8.5%; 5% dimethyl formamide was also effective. Fetal bovine serum was significantly better as an extender when compared with artificial seminal plasma, glucose, and trehalose solution. Sperm tolerated a wide range of cooling rates (from 27.1 to 94.3 °C min^?1); however, the post-thaw motility of sperm cooled to ?30 °C was significantly lower than that of other cooled temperatures (?40 to ?70 °C). The velocity of post-thaw sperm was significantly lower than that of fresh sperm, although LIN remained the same. For effective cryopreservation of seven-band grouper sperm, samples should be diluted in 5% Me₂SO with 95% FBS and cooled to at least ?40 °C before immersion in liquid nitrogen.     

Purification and characterization of a new carbonyl reductase from Leifsonia xyli HS0904 involved in stereoselective reduction of 3,5-bis(trifluoromethyl) acetophenone

Leifsonia xyli HS0904 can stereoselectively catalyze the bioreduction of 3,5-bis(trifluoromethyl) acetophenone (BTAP) to its corresponding alcohol, which is a valuable chiral intermediate in the pharmaceuticals. In this study, a new carbonyl reductase derived from L. xyli HS0904 was purified and its biochemical properties were determined in detail. The carbonyl reductase was purified by 530-fold with a specific activity of 13.2 U mg⁻¹ and found to be a homodimer with a molecular mass of 49 kDa, in which the subunit molecular-weight was about 24 kDa. The purified enzyme exhibited a maximum enzyme activity at 34 °C and pH 7.2, and retained over 90% of its initial activity at 4 °C and pH 7.0 for 24 h. The addition of various additives, such as Ca²⁺, Mg²⁺, Mn²⁺, l-cysteine, l-glutathione, urea, PEG 1000 and PEG 4000, could enhance the enzyme activity. The maximal reaction rate (V_max) and apparent Michaelis–Menten constant (K_m) of the purified carbonyl reductase for BTAP and NADH were confirmed as 33.9 U mg⁻¹, 0.383 mM and 69.9 U mg⁻¹, 0.412 mM, respectively. Furthermore, this enzyme was found to have a broad spectrum of substrate specificity and can asymmetrically catalyze the reduction of a variety of ketones and keto esters.     

Seed storage and germination in Kumara plicatilis,a tree aloe endemic to mountain fynbos in the Boland,south-western Cape,South Africa

Seed storage under appropriate conditions is a relatively inexpensive means of safeguarding plant genetic material for ex situ conservation. Post-storage germination trials are used to determine the viability of stored seeds, and hence the efficacy of the particular storage treatment. Kumara plicatilis (= Aloe plicatilis) is a tree aloe endemic to mountain fynbos in the Boland, south-western Cape. The viability and germination behaviour of K. plicatilis seeds were assessed for seeds stored for four and nine months at − 80 °C, 4 °C, 25 °C and under ambient conditions in a laboratory. Seeds were germinated under controlled conditions and germination rates and percentages determined. Ungerminated seeds were tested for viability using tetrazolium salt. Seed viability was not significantly reduced during storage. Seeds stored at − 80 °C for four and nine months exhibited the fastest germination rate overall (both 5.9 ± 0.3 weeks, mean ± S.E.), and slowest was for seeds stored under ambient conditions for four and nine months (both 7.8 ± 0.4 weeks). All seed lots showed similar percentage germination after four months of storage (78.0–90.4%). The highest percentage germination overall was for seeds stored at − 80 °C for four months (90.4%) and the lowest was for seeds kept at 4 °C and − 80 °C for nine months (39.2 and 39.6%, respectively). Respective percentage viability for ungerminated seeds in these two treatments was 82% and 87%, respectively, indicating the induction of secondary dormancy. Induced dormancy triggered by protracted cold temperatures may be an adaptation that enables seeds to survive prolonged extreme conditions that are unfavourable for germination. Further research on the long-term storage of aloe seeds would be beneficial for developing long-term seed storage and germination testing protocols for ex situ conservation.     

Arboreal gaits in three sympatric rodents Apodemus agrarius,Apodemus flavicollis (Rodentia,Muridae) and Myodes glareolus (Rodentia,Cricetidae)

Vertical stratification of the arboreal habitat allows the coexistence of several species in a given area, because the complex arboreal strata can be used in different ways by arboreal and scansorial mammals. The present report experimentally investigated the gait metrics on different arboreal substrates, of three sympatric rodents living in a deciduous forest in Poznań, Poland. Arboreal locomotion was compared between the burrowing striped field mouse, Apodemus agrarius, the scansorial bank vole, Myodes glareolus, and the more arboreal yellow-necked mouse, Apodemus flavicollis. We filmed two wild-caught individuals from each species walking on four different substrate diameters (2 mm, 5 mm, 10 mm, 25 mm) and three different inclinations (45° descending, horizontal, 45° ascending) at 240 fps and collected a set of gait parameters from a total of 273 complete cycles. Our results did not demonstrate clear relationships between arboreal locomotion and the ecology of the three species. Only A. flavicollis exhibited locomotor features partly associated with arboreal competence, including lower velocity and diagonality on narrow substrates and asymmetrical gaits on wider ones. On the other hand, the two Apodemus species, despite their different ecologies, shared a few locomotor similarities, such as velocity regulation primarily by stride frequency, and similar effects of substrate size and inclination on diagonality, duty factor, and duty factor index indicating the possibility of a phylogenetic signal. Because the selected gait parameters provided limited insight into the ability of small mammals to move competently through an arboreal habitat, these findings indicate that the relationship between behaviour and ecology is complex.     

Apolipoprotein A-I inhibits chemotaxis,adhesion, activation of THP-1 cells and improves the plasma HDL inflammatory index

The anti-inflammatory effects of high density lipoprotein (HDL) are well described, however, such effects of Apolipoprotein A-I (ApoA-I) are less studied. Building on our previous study, we further explored the mechanism of anti-inflammatory effects of ApoA-I, and focused especially on the interaction between monocyte and endothelial cells and plasma HDL inflammatory index in LPS-challenged rabbits. Our results show that ApoA-I significantly decreased LPS-induced MCP-1 release from THP-1 cells and ox-LDL-induced THP-1 migration ratio (P < 0.01, respectively). ApoA-I significantly decreased sL-selectin, sICAM-1 and sVCAM-1 release (P < 0.01, P < 0.01, P < 0.05, respectively) from LPS-stimulated THP-1 cells. Furthermore, ApoA-I significantly inhibited LPS-induced CD11b and VCAM-1 expression on THP-1 cells (P < 0.01, P < 0.05, respectively). ApoA-I diminished LPS-induced mCD14 expression (P < 0.01) and NFκB nuclear translocation in THP-1 cells. After single dose treatment of ApoA-I, the value of plasma HDL inflammatory index in LPS-challenged rabbits was improved significantly (P < 0.05). These results suggest that ApoA-I can inhibit chemotaxis, adhesion and activation of human monocytes and improve plasma HDL inflammatory index with presenting beneficial anti-inflammatory effects.     

Ecophysiological requirements on seed germination of a Mediterranean perennial grass (Stipa tenacissima L.) under controlled temperatures and water stress

Stipa tenacissima L. (alpha grass) steppes are one of the most representative ecosystems in arid Mediterranean ecosystems. On the one hand these steppes, which are perpetually exposed to climate and strong anthropogenic pressure, have undergone severe degradation. On the other hand, the ability of S. tenacissima to regenerate naturally is significantly reduced. In this study the germination response and seedling emergence of S. tenacissima are examined in relation to the main environmental factors (water stress and temperature) under laboratory-controlled conditions. The main aim of this paper was to investigate the influence of temperature over a temperature range (10 °C–30 °C) and water stress induced by the solutions of polyethylene glycol (PEG)-6000 (0 to − 1.6 MPa) for a period of 30 days, on the germination behavior of S. tenacissima seeds. The results showed that temperatures between 10° and 20 °C seem to be favorable for the germination of this species, with optimum temperatures among accessions found in 20 °C. When seeds were water-stressed, germination severely decreased at − 0.8 MPa, indicating that the accession resistance limits to the water stress, and was completely inhibited at − 1.6 MPa. Consequently, the final germination percentage (FGP) decreased and the mean time germination (MTG) increased. Based on the empirical data of the germination rate, we estimated that the parameters of the thermal time and hydrotime models showed different values in all accessions which proves the difference between accession adaptive capacities.     

Effect of thermal stress on metabolic and oxidative stress biomarkers of Hoplosternum littorale (Teleostei,Callichthyidae)

The present study aimed to investigate in Hoplosternum littorale (Hancock, 1828) the effects of different water temperatures (10 °C, 25 °C-control group- and 33 °C) on physiologic and metabolic traits following acute (1 day) and chronic (21 days) exposures. We analyzed several biomarker responses in order to achieve a comprehensive survey of fish physiology and metabolism under the effect of this natural stressor. We measured morphological indices, biochemical and hematological parameters as well as oxidative stress markers. To evaluate energy consumption, muscle and hepatic total lipid, protein and glycogen concentrations were also quantified. Extreme temperatures exposures clearly resulted in metabolic adjustments, being liver energy reserves and plasma metabolites the most sensitive parameters detecting those changes. We observed reduced hepatosomatic index after acute and chronic exposure to 33 °C while glycogen levels decreased at both temperatures and time of exposure tested. Additionally, acute and chronic exposures to 10 °C increased liver lipid content and plasma triglycerides. Total protein concentration was higher in liver and lower in plasma after chronic exposures to 10 °C and 33 °C. Acute exposition at both temperatures caused significant changes in antioxidant enzymes tested in the different tissues without oxidative damage to lipids. Antioxidant defenses in fish failed to protect them when they were exposed for 21 days to 10 °C, promoting higher lipid peroxidation in liver, kidney and gills. According to multivariate analysis, oxidative stress and metabolic biomarkers clearly differentiated fish exposed chronically to 10 °C. Taken together, these results demonstrated that cold exposure was more stressful for H. littorale than heat stress. However, this species could cope with variations in temperature, allowing physiological processes and biochemical reactions to proceed efficiently at different temperatures and times of exposure. Our study showed the ability of H. littorale to resist a wide range of environmental temperatures and contributes for the understanding of how this species is adapted to environments with highly variable physicochemical conditions.     

Separation and purification of laccases from two different fungi using aqueous two-phase extraction

Selective purification still poses a challenge in the downstream processing of biomolecules such as proteins and especially enzymes. In this study a polyethylene glycol 3000 (PEG 3000)–phosphate aqueous two-phase system at 25 °C and pH 7 was successfully used for laccase purification and separation. Initially, the effect of phase forming components on enzyme activities in homogenous systems was studied. In the course of the extraction experiments tie lines, enzyme source, initial enzyme activities, phase ratio and sodium chloride concentrations were varied and their influence on the activity partitioning was determined. Partitioning results were validated using clear-native-PAGE and isoelectric focusing. Based on these results, the separation of laccases from Trametes versicolor and Pleurotus sapidus was investigated using the principle of superposition. Sodium chloride was used to adjust laccase partitioning in the applied aqueous two-phase system (ATPS). Finally, two modes of operation are proposed depending on the aim of the purification task. One mode with 0.133 g g⁻¹ of PEG3000, 0.063 g g⁻¹ of phosphate and without sodium chloride separates P. sapidus laccases from T. versicolor laccases with clearance factors of 5.23 and 6.45, respectively. The other mode of operation with 0.124 g g⁻¹ of PEG3000, 0.063 g g⁻¹ of phosphate and 0.013 g g⁻¹ of sodium chloride enables a partitioning of both laccases into the bottom phase of the ATPS resulting in a purification factor of 2.74 and 96% activity recovery.     

Effect of variable dew temperatures on infection of green foxtail by Pyricularia setariae,Drechslera gigantea,and Exserohilum rostratum

A thermogradient apparatus was used to investigate the effect of variable dew temperatures on infection of green foxtail by the indigenous pathogen Pyricularia setariae (Ps) and the exotic pathogens Drechslera gigantea (Dg), and Exserohilum rostratum (Er) from the southern USA that showed bioherbicide potential against several grassy weeds. This device is capable of creating multiple diurnal temperature cycles, mimicking daily temperature fluctuations that occur under field conditions. Seven temperature regimes, i.e., 15/10 °C, 20/5 °C, 20/15 °C, 25/10 °C, 25/20 °C, 30/15 °C, and 30/25 °C (maximum/minimum), were used with temperature cycling from maximum to minimum and then back up to maximum in a 24 h period. Ps and Dg were much more virulent than Er on green foxtail, resulting in higher levels of disease and weed control. Dg was little affected by the dew temperatures in terms of plant infection and was more efficacious than Ps under cooler dew temperatures (15/10 °C and 20/5 °C), causing twice as much disease. This greater amount of disease coincided with higher conidial germination, appressorial formation and infection-hypha frequency by Dg at the lower temperatures. The efficacy of Ps improved as dew temperature increased, accompanied by a higher percentage of germination and more frequent appressorial production. Dg caused severe disease 2 d after inoculation whereas Ps required 4 d to initiate disease symptoms. These observations suggest that Dg is a superior candidate than Ps for green foxtail control on the Canadian prairies.     

Behavioral thermoregulation and critical thermal limits of giant keyhole limpet Megathura crenulata (Sowerby 1825) (Mollusca; Vetigastropoda)

The thermoregulatory behavior of the giant keyhole limpet Megathura crenulata was determined in a horizontal thermal gradient during the day at 18.9 °C and 18.3 °C for the night. The final preferendum determined for giant keyhole limpets was of 18.6±1.2 °C.Limpets' displacement velocity was 10.0±3.9 cm h⁻¹ during the light phase and 8.4±1.6 cm h⁻¹ during the dark phase. The thermotolerance (measured as CTMax at 50%) was determined in a keyhole limpet in three acclimation temperatures 17, 20, and 23 °C. Limpets were subjected to water increasing temperatures at a rate of 1 °C every 30 min, until they detached from the substrate. The critical thermal maximum at 50% was 27.2, 27.9 and 28.3 °C respectively.     

The in vitro effect of temperature on motility and antioxidant response of common carp Cyprinus carpio spermatozoa

The effect of temperature on Cyprinus carpio spermatozoa in vitro was investigated with spermatozoa activated at 4, 14, and 24 °C. At 30 s post-activation, motility rate was significantly higher at 4 °C compared to 14 and 24 °C, whereas highest swimming velocity was observed at 14 °C. The thiobarbituric acid-reactive substance (TBARS) content was significantly higher at 14 °C and 24 °C than at 4 °C in motile spermatozoa. No significant differences in catalase and superoxide dismutase activity relative to temperature were observed. This study provides new information regarding effect of temperature on lipid peroxidation intensity and spermatozoon motility parameters in carp. The elevation of TBARS seen at higher temperatures could be due to inadequate capacity of antioxidant enzymes to protect the cell against the detrimental effects of oxidative stress induced by higher temperatures.