Effect of dsRNA on growth rate and reproductive potential of Monosporascus cannonballus

The effect of double stranded RNA (dsRNA) infection on growth rate and the reproductive potential of Monosporascus cannonballus was studied in 21 isolates collected in cucurbit growing areas of Spain and Tunisia. The isolates were incubated on potato dextrose agar (PDA) under different conditions of temperature, pH, and water potential (Ψ(s)). They showed optimal growth temperatures over the range of 27-34°C and perithecia formation was obtained mainly at 25 and 30°C, although some isolates were able to produce perithecia at 35°C. All isolates were able to produce perithecia in a broad range of pHs (4-8). Regarding the effect of Ψ(s,) the isolates were more tolerant to grow on KCl than on NaCl. For each solute, radial growth decreased progressively as Ψ(s) decreased and was severely limited at -5.0 to -6.0MPa. Perithecia formation was highest at -0.5MPa, decreased at -1.0MPa and occurred just in some isolates at -2.0MPa. Nine of the M. cannonballus isolates harboured dsRNA with 2-6 bands each and a size range of 1.9-18.0Kb. Phenotypical data were subjected to multivariate factorial analysis. Most of the isolates clustered in two groups corresponding with the presence/absence of dsRNA elements. Isolates without detectable dsRNA produced more perithecia. However, isolates with dsRNA produced lower number of perithecia depending on the pH, Ψ(s,) or solute used. These results improve our understanding of the behaviour and growth of this pathogen in soil, and can be useful to implement effective disease control.     

Properties and potential medical applications of regenerated casein fibers crosslinked with citric acid

Regenerated protein fibers developed from casein using alkaline solutions and crosslinked with citric acid have good tensile properties and water stability but were cytotoxic. Casein is obtained as a byproduct during skim milk production but has limited industrial applications. In this research, casein was dissolved using alkaline solutions and the effects of fiber formation conditions on the tensile properties was studied before and after crosslinking with citric acid. Crosslinked casein fibers had tensile strength as high as 110 MPa and breaking elongation of 13.6%. The fibers were also stable in 90°C water between pH 3 and 9 but were hydrolyzed at pH 11. Casein was cytotoxic and did not support the attachment and growth of mouse fibroblasts.     

The effect of season and light intensity on the core interthreshold zone

The hypothesis tested in the present study is a seasonal difference in the core interthreshold zone (CIZ), as we suggested in an earlier study that individual awareness of heat may change the CIZ due to thermoregulatory behavior. A series of human experiments were carried out in a climatic chamber in January and August of 2009 and January of 2010. The air temperature in the chamber was controlled at 20-24°C. Subjects wore a water-perfused suit that was perfused with 25°C water at a rate of 600 cc/min. They exercised on an ergometer at 50% of their maximum work rate for 10-15 min until their sweating rate increased and then remained seated without exercise until oxygen uptake increased. Subjects' rectal temperature and skin temperatures at four sites were monitored by thermistors. The sweating rate was measured at the forehead with a sweat rate monitor (SKD 4000, Skinos Co.). Oxygen uptake was monitored with a gas analyzer (Respiromonitor RM-300i, Minato Med. Science Co.). In the 2009 winter experiment, 5 male subjects were exposed to lighting of 36 cd/m(2)/1,050 lx, and in the 2009 summer and 2010 winter experiments, 10 male subjects were exposed to lighting of 18 cd/m2/510 lx. The results showed that the CIZ of 0.69±0.29°C (n=22, data from 2005-2007 experiments) at 36 cd/m(2) and that of 0.37±0.17°C (n=10) at 18 cd/m(2) in summer were greater than the CIZ of 0.37±0.13°C (n=5) at 36 cd/m(2) and that of 0.18±0.17°C (n=10) at 18 cd/m(2) in winter, and thus demonstrated a seasonal difference in the CIZ as well as an effect of lighting conditions on the CIZ.     

Complete genome sequence of the obligate piezophilic hyperthermophilic archaeon Pyrococcus yayanosii CH1

Pyrococcus yayanosii CH1 is the first obligate piezophilic hyperthermophilic archaeon isolated from the deep-sea hydrothermal site Ashadze on the mid-Atlantic ridge at a depth of 4,100 m. This organism grows within a temperature range of 80 to 108°C and a hydrostatic pressure range of 20 to 120 MPa, with optima at 98°C and 52 MPa, respectively. Here, we report the complete genome sequence (1,716,817 bp, with a G+C content of 51.6%) of the type strain P. yayanosii CH1(T) (= JCM 16557). This genomic information reveals a systematic view of the piezoadaptation strategy and evolution scenario of metabolic pathways in Thermococcales.     

Effects of flow and temperature on growth and photophysiology of scleractinian corals in Moorea, French Polynesia

To test for threshold effects in the response of coral physiology to increasing seawater flow, field and laboratory experiments were conducted in Moorea. First, the growth of juvenile massive Porites spp. and branching P. irregularis was compared among habitats differing in water motion. Growth of massive Porites spp. responded to flow in a pattern consistent with a threshold effect, whereas growth of P. irregularis increased linearly with flow. Second, a recirculating flume was used to test the effect of flow on photophysiology (ΔF/F(m)', effective photochemical efficiency) for massive Porites spp.; ΔF/F(m)' displayed a threshold response at 23 cm s(-1) and 28 °C, but not at 31 °C. Finally, intra-colony variation in the response of ΔF/F(m)' to flow and temperature was explored to evaluate the functional significance of colony shape in small corals. ΔF/F(m)' on the top and upstream surfaces of massive Porites spp. responded with a threshold effect of flow at 28 °C (but not 31 °C), but ΔF/F(m)' on downstream surfaces was unresponsive to flow. ΔF/F(m)' for P. irregularis was less responsive to flow than for massive Porites spp., suggesting that the photophysiological response of corals to varying flow speeds may differ between species and morphologies. Together, these results emphasize that flow can have diverse effects on the physiology of corals, with the outcome depending on flow speed, temperature, location on the colony, and perhaps morphology.     

Light and turgor affect the water permeability (aquaporins) of parenchyma cells in the midrib of leaves of Zea mays

In response to light, water relation parameters (turgor, half-time of water exchange, T(1/2), and hydraulic conductivity, Lp; T(1/2) proportional 1/Lp) of individual cells of parenchyma sitting in the midrib of leaves of intact corn (Zea mays L.) plants were investigated using a cell pressure probe. Parenchyma cells were used as model cells for the leaf mesophyll, because they are close to photosynthetically active cells at the abaxial surface, and there are stomata at both the adaxial and abaxial sides. Turgor ranged from 0.2 to 1.0 MPa under laboratory light condition (40 micromol m(-2) s(-1) at the tissue level), and individual cells could be measured for up to 6 h avoiding the variability between cells. In accordance with earlier findings, there was a big variability in T(1/2)s measured ranging from 0.5 s to 100 s, but the action of light on T(1/2)s could nevertheless be worked out for cells having T(1/2)s greater than 2 s. Increasing light intensity ranging from 100 micromol m(-2) s(-1) to 650 micromol m(-2) s(-1) decreased T(1/2) by a factor up to five within 10 min and increased Lp (and aquaporin activity) by the same factor. In the presence of light, turgor decreased due to an increase in transpiration, and this tended to compensate or even overcompensated for the effect of light on T(1/2). For example, during prolonged illumination, cell turgor dropped from 0.2 to 1.0 MPa to -0.03 to 0.4 MPa, and this drop caused an increase of T(1/2) and a reduction of cell Lp, i.e. there was an effect of turgor on cell Lp besides that of light. To separate the two effects, cell turgor (water potential) was kept constant while changing light intensity by applying gas pressure to the roots using a pressure chamber. At a light intensity of 160 micromol m(-2) s(-1), there was a reduction of T(1/2) by a factor of 2.5 after 10-30 min, when turgor was constant within +/-0.05 MPa. Overall, the effects of light on T(1/2) (Lp) were overriding those of turgor only when decreases in turgor were less than about 0.2 MPa. Otherwise, turgor became the dominant factor. The results indicate that the hydraulic conductivity increased with increasing light intensity tending to improve the water status of the shoot. However, when transpiration induced by light tends to cause a low turgidity of the tissue, cell Lp was reduced. It is concluded that, when measuring the overall hydraulic conductivity of leaves, both the effects of light and turgor should be considered. Although the mechanism(s) of how light and turgor influence the cell Lp is still missing, it most likely involves the gating of aquaporins by both parameters.     

Comparative ecophysiological measurements on the light responses,water relations and desiccation tolerance of the filmy ferns Hymenophyllum wilsonii Hook. and H. tunbrigense (L.) Smith

Chlorophyll-fluorescence and infrared gas analyser measurements show saturation of photosynthetic electron flow and CO(2) uptake at generally lower irradiances in Hymenophyllum tunbrigense than in H. wilsonii, but with wide variation in both species (63-189 micromol m(-2) s(-1) PPFD in H. tunbrigense, 129-552 micro mol m(-2) s(-1) PPFD in H. wilsonii), probably related to both site and season. Non-photochemical quenching (at 400 micromol m(-2) s(-1) PPFD) ranged from 2.1 to 8.1, with no significant difference between the species. Pressure-volume curves from thermocouple-psychrometer measurements give full-turgor osmotic potentials of approx. -1.4 MPa in both species, and indicate low apoplast fractions and high cell-wall elastic moduli. Leaves of H. tunbrigense recovered within 24 h from up to 7 d desiccation at water potentials ranging from -40 MPa (74 % relative humidity, RH) to -220 MPa (20 % RH); after 15 or 30 d, desiccation recovery was slower and less complete, and leaves were severely damaged at the highest and lowest humidities. Hymenophyllum wilsonii recovered well from up to 30 d desiccation at -114 and -220 MPa, but at -40 MPa it showed signs of damage after 15 d, and was severely damaged or killed after 30 d. Results are discussed in relation to the ecological and geographical distributions of the two species, and to the adaptive strategies of filmy ferns in general.     

Characterization and solvent engineering of wheat β-amylase for enhancing its activity and stability

The kinetic and thermodynamic parameters of wheat β-amylase (WBA) were characterized and various additives were evaluated for enhancing its activity and thermostability. WBA activity was examined by neocuproine method using soluble starch as substrate. The Michaelis constant (K(m)) and molecular activity (k(cat)) were determined to be 1.0±0.1% (w/v) and 94±3s(-1), respectively, at pH 5.4 and at 25°C. The optimum reaction temperature (T(opt)) for WBA activity was 55°C and the temperature (T(50)) at which it loses half of the activity after 30-min incubation was 50±1°C. Modifications of the solvent with 182mM glycine and 0.18% (w/v) gelatin have increased the T(50) by 5°C. Glycerol, ethylene glycol, dimethylformamide (DMF) and dimethyl sulfoxide have also slightly enhanced the thermostability plausibly through weakening the water structure and decreasing the water shell around the WBA protein. Ethanol and DMF activated WBA by up to 24% at 25°C probably by inducing favorable conformation for the active site or changing the substrate structure by weakening the hydrogen bonding. Its half-life in the inactivation at 55°C was improved from 23 to 48min by 182mM glycine. The thermodynamic parameters indicate that WBA is thermo-labile and sufficient stabilization was achieved through solvent modification with additives and that the heat inactivation of WBA is entropic-driven. It is suggested that WBA could be applied more widely in starch-saccharification industries with employing suitable additives.     

Purification and characterization of a novel and unique ginsenoside Rg1-hydrolyzing β-D-glucosidase from Penicillium sclerotiorum

In this paper, a novel and unique ginsenoside Rg(1)-hydrolyzing β-D-glucosidase from Penicillium sclerotiorum was isolated, characterized, and generally described. The β-glucosidase is an ~180 kDa glycoprotein with pI 6.5, and consists of four identical subunits of ~40 kDa. The β-glucosidase was active in a narrow pH range (4-5) and at relatively high temperature (60-70°C). The optimal activity against p-nitrophenyl-β-D-glucopyranoside (pNPG) was as follows: pH 4.5 and temperature 65°C. Under these conditions, the K(m) of the enzyme was 0.715 mM with a V(max) of 0.243 mmol nitrophenol/min mg. Metal ions such as Ba(2+), K(+), Fe(3+), and Co(2+) significantly promoted the enzymatic activity, while Ca(2+), Mg(2+), and Ag(+) inhibited its activity. Of the tested substrates, only ginsenoside Rg(1) could be specifically hydrolyzed by the β-glucosidase at the C6-glucoside to form the rare ginsenoside F(1). These properties were novel and different from those of other previously described glycosidases.     

Biochemical characterization of two novel β-glucosidase genes by metagenome expression cloning

Two novel β-glucosidase genes designated as bgl1D and bgl1E, which encode 172- and 151-aa peptides, respectively, were cloned by function-based screening of a metagenomic library from uncultured soil microorganisms. Sequence analyses indicated that Bgl1D and Bgl1E exhibited lower similarities with some putative β-glucosidases. Functional characterization through high-performance liquid chromatography demonstrated that purified recombinant Bgl1D and Bgl1E proteins hydrolyzed D-glucosyl-β-(1-4)-D-glucose to glucose. Using p-nitrophenyl-β-D-glucoside as substrate, K(m) was 0.54 and 2.11 mM, and k(cat)/K(m) was 1489 and 787 mM(-1) min(-1) for Bgl1D and Bgl1E, respectively. The optimum pH and temperature for Bgl1D was pH 10.0 and 30°C, while the optimum values for Bgl1E were pH 10.0 and 25°C. Bgl1D exhibited habitat-specific characteristics, including higher activity in lower temperature and at high concentrations of AlCl(3) and LiCl. Bgl1D also displayed remarkable activity across a broad pH range (5.5-10.5), making it a potential candidate for industrial applications.     

Genetic surface-display of methyl parathion hydrolase on Yarrowia lipolytica for removal of methyl parathion in water

In this study, the mph gene encoding methyl parathion hydrolase from Pseudomonas sp. WBC-3 was expressed in Yarrowia lipolytica and the expressed methyl parathion hydrolase was displayed on cell surface of Y. lipolytica. The activity of methyl parathion hydrolase displayed on the yeast cells of the transformant Z51 was 59.5 U mg?1 of cell dry cells (450.6 U per mL of the culture) in the presence of 5.0 mM of Co2?. The displayed methyl parathion hydrolase had the optimal pH of 9.5 and the optimal temperature of 40 °C, respectively and was stable in the pH range of 4.5-11 and up to 40 °C. The displayed methyl parathion hydrolase was also stimulated by Co2?, Cu2?, Ni2? and Mn2?, and was not affected by Fe2?, Fe3?, Na?, K?, Ca2? and Zn2?, but was inhibited by other cations tested. Under the optimal conditions (OD(600 nm) = 2.6, the substrate concentration = 100 mg L?1 and 40 °C), 90.8 % of methyl parathion was hydrolyzed within 30 min. Under the similar conditions, 98.7, 97.0, 96.5 and 94.4 % of methyl parathion in tap water (pH 9.5), tap water (pH 6.8), seawater (pH 9.5) and natural seawater (pH 8.2) were hydrolyzed, respectively, suggesting that the methyl parathion hydrolase displayed on the yeast cells can effectively remove methyl parathion in water.     

Modelling photosynthetic responses to temperature of grapevine (Vitis vinifera cv. Semillon) leaves on vines grown in a hot climate

Field measurements of photosynthesis of Vitis vinifera cv. Semillon leaves in relation to a hot climate, and responses to photon flux densities (PFDs) and internal CO(2) concentrations (c(i) ) at leaf temperatures from 20 to 40 °C were undertaken. Average rates of photosynthesis measured in situ decreased with increasing temperature and were 60% inhibited at 45 °C compared with 25 °C. This reduction in photosynthesis was attributed to 15-30% stomatal closure. Light response curves at different temperatures revealed light-saturated photosynthesis optimal at 30 °C but also PFDs saturating photosynthesis increased from 550 to 1200 μmol (photons) m(-2)s(-1) as temperatures increased. Photosynthesis under saturating CO(2) concentrations was optimal at 36 °C while maximum rates of ribulose 1,5-bisphosphate (RuBP) carboxylation (V(cmax)) and potential maximum electron transport rates (J(max)) were also optimal at 39 and 36 °C, respectively. Furthermore, the high temperature-induced reduction in photosynthesis at ambient CO(2) was largely eliminated. The chloroplast CO(2) concentration at the transition from RuBP regeneration to RuBP carboxylation-limited assimilation increased steeply with an increase in leaf temperature. Semillon assimilation in situ was limited by RuBP regeneration below 30 °C and above limited by RuBP carboxylation, suggesting high temperatures are detrimental to carbon fixation in this species.     

Identification and characterization of UDP-glucose dehydrogenase from the hyperthermophilic archaon, Pyrobaculum islandicum

A gene encoding a UDP-glucose dehydrogenase homologue was identified in the hyperthermophilic archaeon, Pyrobaculum islandicum. This gene was expressed in Escherichia coli, and the product was purified and characterized. The expressed enzyme is the most thermostable UDP-glucose dehydrogenase so far described, with a half-life of 10 min at 90 °C. The enzyme retained its full activity after incubating in a pH range of 5.0-10.0 for 10 min at 80 °C. The temperature dependence of the kinetic parameters for this enzyme was examined at 37-70 °C. A decrease in K(m)s for UDP-glucose and NAD was observed with decreasing temperature. This resulted in the enzyme still retaining high catalytic efficiency (V(max)/K(m)) for the substrate and cofactor, even at 37 °C. These characteristics make the enzyme potentially useful for its application at a much lower temperature such as 37 °C than the optimum growth temperature of 100 °C for P. islandicum.     

霜冻过程温光因子分析及模拟霜冻条件的建立

近年来霜冻对我国果树产业的影响越来越大, 建立科学的模拟霜冻程序对于加强果树霜冻基础研究十分必要。基于对大田霜冻天气的实际观测, 分析了自然霜冻在降温速度、低温极限、升温速度以及霜后光照条件方面的特点, 建立了用于实验室环境下的霜冻处理程序。结果表明, 霜冻发生时气温的变化主要包括降温、低温维持和升温3个阶段。降温和升温阶段气温的变化近似线性; 霜后一般伴随较强的光照。经研究确定模拟霜冻条件为: 黑暗环境下, 气温在30分钟内从室温(20°C)降到5°C, 在5°C维持30分钟, 之后以0.8°C·h ^-1的速度降到-2°C, 在-2°C维持2小时, 再以4.7°C·h ^-1的速度回升到5°C结束霜冻处理。霜冻处理后的恢复条件为气温16°C及光强800 μmol·m ^-2·s ^-1。     

The effect of temperature on sperm motility and enzymatic activity in brown trout Salmo trutta, burbot Lota lota and grayling Thymallus thymallus

The effect of temperature on sperm motility was investigated in brown trout Salmo trutta, burbot Lota lota and grayling Thymallus thymallus using water and sperm motility prolonging saline solution (SMPS) for motility activation. The effect of temperature (4-20° C) on spermatozoal enzymes for energy supply [malate dehydrogenase (MDH), pyruvate kinase (PK), adenylate kinase (AK)], flagellar movement [Mg(2+) adenosine triposphatase (ATPase)] and oxidative defence [peroxidase (POX)] were measured in S. trutta and L. lota. Temperatures yielding the highest initial sperm motility rates and swimming velocities were 4-6° C for S. trutta [investigated range (IR) = 4-12° C] and L. lota (IR = 2-8° C) and 8-16° C (IR = 4-16° C) for T. thymallus. Motility variables were re-measured after 30 s in S. trutta, after 45 s in T. thymallus and after 60 s in L. lota in water and after 2 min in all investigated species in SMPS. Motility variables were increased by low temperatures and the results differed between water and SMPS. In S. trutta and L. lota, the temperature resulting in highest activities of MDH, PK, AK and ATPase was 4° C. POX had a very narrow temperature optimum at 20° C in both species. This may indicate that the temperature optimum of enzymes of energy supply and flagellar movement are closely related to motility. The present data show that the variables are affected by temperatures in an ecologically relevant range. Too low, as well as too high temperatures affected sperm motility, and the winter spawners (S. trutta and L. lota) have a narrower temperature optimum than the spring spawner T. thymallus.     

Supercooling and vitrification of aqueous glycerol solutions at normal and high pressures

The supercooling and vitrification of aqueous glycerol solutions was studied at high pressures. Homogeneous ice nucleation temperatures (T(H)) were obtained for aqueous glycerol solutions of R=50, 30, 20, 12, and 10 (R: moles of water/moles of glycerol) up to 300MPa. The R=20 glycerol solution formed a glass above 200MPa at a cooling rate of 200°C/min, indicating that pressure enhances glass-formation of aqueous glycerol solutions. The (dT(g)/dP) values were obtained for vitrified aqueous glycerol solutions of R=3, 5, 10, and 20. These data can be used for the development of cryo-preservation liquids for living cells at high pressures.     

Sweat rate prediction equations for outdoor exercise with transient solar radiation

We investigated the validity of employing a fuzzy piecewise prediction equation (PW) [Gonzalez et al. J Appl Physiol 107: 379-388, 2009] defined by sweat rate (m(sw), g·m(-2)·h(-1)) = 147 + 1.527·(E(req)) - 0.87·(E(max)), which integrates evaporation required (E(req)) and the maximum evaporative capacity of the environment (E(max)). Heat exchange and physiological responses were determined throughout the trials. Environmental conditions were ambient temperature (T(a)) = 16-26°C, relative humidity (RH) = 51-55%, and wind speed (V) = 0.5-1.5 m/s. Volunteers wore military fatigues [clothing evaporative potential (i(m)/clo) = 0.33] and carried loads (15-31 kg) while marching 14-37 km over variable terrains either at night (N = 77, trials 1-5) or night with increasing daylight (N = 33, trials 6 and 7). PW was modified (Pw,sol) for transient solar radiation (R(sol), W) determined from measured solar loads and verified in trials 6 and 7. PW provided a valid m(sw) prediction during night trials (1-5) matching previous laboratory values and verified by bootstrap correlation (r(bs) of 0.81, SE ± 0.014, SEE = ± 69.2 g·m(-2)·h(-1)). For trials 6 and 7, E(req) and E(max) components included R(sol) applying a modified equation Pw,sol, in which m(sw) = 147 + 1.527·(E(req,sol)) - 0.87·(E(max)). Linear prediction of m(sw) = 0.72·Pw,sol + 135 (N = 33) was validated (R(2) = 0.92; SEE = ±33.8 g·m(-2)·h(-1)) with PW β-coefficients unaltered during field marches between 16°C and 26°C T(a) for m(sw) ≤ 700 g·m(-2)·h(-1). PW was additionally derived for cool laboratory/night conditions (T(a) < 20°C) in which E(req) is low but E(max) is high, as: PW,cool (g·m(-2)·h(-1)) = 350 + 1.527·E(req) - 0.87·E(max). These sweat prediction equations allow valid tools for civilian, sports, and military medicine communities to predict water needs during a variety of heat stress/exercise conditions.     

Enzymatic hydrolysis of willow treated with a steam burst without preliminary water extraction with a high concentration of substrate

A laboratory reactor equipped with a screw press was used for hydrolysis of steam-SO2 exploded willow Salix caprea by a composition of Trichoderma reesei and Aspergillus foetidus enzyme preparations at high substrate concentrations. Optimal conditions providing the maximal volume of hydrolysis syrup with maximal sugar concentrations were determined. Two different hydrolysis procedures were developed in order to exclude initial washing of steam-pretreated plant raw material by large volumes of water, which is necessary to eliminate the inhibitory effect of explosion by-products on enzymatic hydrolysis. The first procedure included a one-hour-long enzymatic prehydrolysis of the substrate, then separation of sugar syrup containing 40-60 g/l of glucose, 20-25 g/l of xylose, and up to 10% of disaccharides, as well as up to 35% of the initial enzymatic activity, then addition of a diluted acetate buffer (pH 4.5), and subsequent hydrolysis of the substrate by the adsorbed enzymes leading to the final accumulation of up to 140 g/l glucose and up to 15 g/l xylose. In the second scenario, the exploded willow was initially adjusted by alkali to pH 4.5 and then hydrolyzed directly by added enzymes for 24 hours. This procedure resulted in a nearly total polysaccharide hydrolysis and accumulation of up to 170 g/l glucose and 20 g/l xylose. The reasons of inhibition of enzymatic hydrolysis are discussed.     

Inactivation of Escherichia coli O157:H7 on radish seeds by sequential treatments with chlorine dioxide, drying, and dry heat without loss of seed viability

We developed and validated a treatment to inactivate Escherichia coli O157:H7 on radish seeds without decreasing seed viability. Treatments with aqueous ClO(2) followed by drying and dry-heat treatments were evaluated for efficacy to inactivate the pathogen. Conditions to dry radish seeds after treatment with water (control) or ClO(2) were established. When treated seeds with high water activity (a(w)) (>0.99) were stored at 45°C and 23% relative humidity (RH), the a(w) decreased to <0.30 within 24 h. Drying high-a(w) seeds before exposing them to dry-heat treatment (≥60°C) was essential to preserve seed viability. The germination rate of radish seeds which had been immersed in water for 5 min, dried at 45°C and 23% RH for 24 h, and heated at 70°C for 48 h or at 80°C for 24 h was not significantly decreased (P ≤ 0.05) compared to that of untreated radish seeds. Sequential treatments with ClO(2) (500 μg/ml, 5 min), drying (45°C, 23% RH, 24 h), and dry heating (70°C, 23% RH, 48 h) eliminated E. coli O157:H7 (5.9 log CFU/g) on radish seeds and, consequently, sprouts produced from them without decreasing the germination rate. These sequential treatments are recommended for application to radish seeds intended for sprout production.     

Temperature effects on immune response and hematological parameters of channel catfish Ictalurus punctatus vaccinated with live theronts of Ichthyophthirius multifiliis

This study evaluated the influence of temperature on the immune responses and hematological parameters in channel catfish Ictalurus punctatus immunized via intraperitoneal injection with live theronts of Ichthyophthirius multifiliis. Fish were distributed in 18 aquaria and received 9 treatments: 4 groups of fish were vaccinated with live theronts and maintained at constant temperature 15 °C, 20 °C, 25 °C and 30 °C; 3 groups of fish vaccinated and subjected to cycling temperature regime from 15-25 °C, 20-25 °C and 20-30 °C, changed 5 °C each day; 2 groups of fish were not vaccinated and served as controls at 25 °C, one with Ich challenge and the other without challenge. Non vaccinated fish and those vaccinated at 15 °C or 15-25 °C did not show anti-Ich antibodies in the serum 14 and 21 days post-immunization. The antibody levels were significantly higher from fish vaccinated at 25 °C, 30 °C, 20-25 °C and 20-30 °C compared to fish at 15 °C, 20 °C and 15-25 °C both 14 and 21 days post-immunization. At constant water temperature, fish vaccinated at 15 °C showed significantly higher mortality rate (67.8%, P < 0.05) than those vaccinated at 20 °C, 25 °C, and 30 °C (0-10.7% mortalities). At cycling water temperature, fish vaccinated at 15-25 °C showed significantly higher mortality rate (67.8%) than those vaccinated at 20-25 °C and 20-30 °C (P < 0.05). Twenty days after immunization fish vaccinated at 30 °C and 20-30 °C showed significant increase in the red blood cells, white blood cells, thrombocytes and monocytes. Six days after challenge with I. multifiliis theronts the fish showed decreased white blood cells, thrombocytes and monocytes. This study suggests that vaccinated catfish were severely impacted by low temperature, either at 15 °C constant temperature or at 15-25 °C cycling temperature. The fish showed no anti-Ich antibodies and suffered high mortality similar to non vaccinated control fish.