产紫青霉突变菌株Li-3-9的发酵条件优化及红色素安全性评价

本实验对前期研究得到的具有高产红色素能力的产紫青霉突变菌株Penicillium purpurogenum Li-3-9的发酵条件进行优化的同时作出了对红色素的安全性评价。在单因素试验的基础上,采用Box-Behnken试验设计优化了蔗糖浓度、酵母膏浓度和装液量对红色素色价的影响;并且研究了P. purpurogenum Li-3-9产生的红色素对斑马鱼胚胎的毒性效应。结果表明,最佳发酵条件为：蔗糖40g/L、酵母膏4g/L、装液量为45mL、接种量4%、培养温度32℃、初始pH值6.9、培养时间168h、摇床转速150r/min,红色素色价最高达到了11.4U/mL。通过计算斑马鱼胚胎致死率、心率、畸形率及孵化率可知,该色素无致死毒性,并且对斑马鱼胚胎发育具有一定的促进作用。     

Optimization of initial substrate and pH levels for germination of sporing hydrogen-producing anaerobes in cow dung compost

Biohydrogen production by anaerobic microbes enriched from heat-shocked cow dung compost was studied by using an artificial medium containing sucrose. Initial pH and substrate levels were selected as target factors in this study. Our experimental results demonstrated that optimal substrate concentration and pH for the composts generating hydrogen gas were 4.0+/-0.5 g sucrose/l and 5.4+/-0.2, respectively. Supplementary experiments confirmed that chemical oxygen demand reduction efficiency (69%) obtained from the conditions of sucrose=4.0 g/l and pH=5.5 was significantly greater than that (37%) from sucrose=5.0 g/l and pH=5.0. Experimental results of metabolites analysis led us to the conclusion that Clostridium sp. predominated in the anaerobic composts, suggesting that inocula used to seed the batch experiment can be obtained from a common natural source.     

Attracticidal spheres for controlling apple maggot flies: commercial-orchard trials

Wooden pesticide-treated red spheres and biodegradable sugar/flour pesticide-treated red spheres were compared with wooden sticky-coated red spheres and insecticide sprays for controlling apple maggot flies, Rhagoletis pomonella(Walsh) (Diptera: Tephritidae), in small blocks of apple trees in Massachusetts commercial orchards in 1997, 1998 and 1999. Pesticide-treated spheres received a coating of 70% latex paint, 20% feeding stimulant (sucrose), and 10% formulated insecticide (containing 20% imidacloprid). To replenish sucrose lost during rainfall, wooden spheres were capped with a disc comprised of hardened sucrose that seeped onto the sphere surface, whereas the surface of sugar/flour spheres received sucrose that seeped from the interior. Each year, each of the 24 perimeter trees of each non-sprayed block received a sphere baited with butyl hexanoate (an attractive component of host fruit odor), with the intent of intercepting immigrating flies. Based on captures of flies on unbaited sticky-coated red spheres placed near the center of each block and on periodic samples of fruit for injury, there was a consistent pattern of treatment performance. Each year, sticky-coated spheres were only slightly less effective than two or three sprays of organophosphate insecticide, sugar/flour pesticide-treated spheres were only slightly less effective than sticky spheres, and wooden pesticide-treated spheres were least effective. Versions of pesticide-treated spheres used in 1999 were more durable than those used in previous years, but further improvement is needed before either wooden or sugar/flour pesticide-treated spheres can be recommended for grower use.     

Sugar concentration and timing of feeding affect feeding characteristics and survival of a parasitic wasp

The availability of food sources is important for parasitoid survival, especially for those that inhabit ecosystems where nectar and honeydew are spatially or temporally scarce. Therefore, the value of even a single meal can be crucial for survival. Psyttalia lounsburyi is a parasitoid, and biological control agent, of the olive fruit fly, Bactrocera oleae. In order to improve our understanding of the basic nutritional ecology of P. lounsburyi and its role in survival we evaluated the effect of a single sucrose meal on the longevity of female and male wasps. We measured the duration of feeding, volume ingested, sucrose consumption, energy content, and longevity of wasps provided with different concentrations of sucrose (0.5, 1, and 2 M) at different times after emergence (0, 1, 2 or 3 days after emergence). Our results showed that longevity was significantly influenced by sucrose concentration and timing of feeding. For females, feeding on sucrose increased the likelihood of survival to varying degrees, ranging from 32.3% to 95.4%, compared to water-only controls. The longest duration of feeding was observed for the highest sucrose concentrations and oldest wasps. The amount of sugar ingested and energy uptake increased, up to a point, as sugar concentration increased. Our results suggest that P. lounsburyi derived greatest benefit from the intermediate concentration (1 M) of sucrose provided 2 or 3 days after emergence. Our study emphasizes the importance of finding balance between increasing longevity and limiting the duration of feeding, and concomitant uptake of nutrients, that is fundamental for survival of the wasp in nature.     

Toxicity and residual effectiveness of insecticides on insecticide-treated spheres for controlling females of Rhagoletis pomonella (Diptera: Tephritidae)

This study evaluated the toxicity of five technical-grade insecticides of four different classes to apple maggot females, Rhagoletis pomonella (Walsh), following a 10-min exposure period in insecticide-coated glass jars, with or without a feeding stimulant (sucrose) present. According to LC90 values for toxicity by ingestion and tarsal contact, imidacloprid was 1.5 times more toxic than dimethoate or abamectin, diazinon was less toxic, and phloxine B (a phototoxic dye) least toxic. Based on LC90 values for tarsal contact alone, dimethoate was 2.3, 4.0, and 18.4 times more toxic than imidacloprid, abamectin, and diazinon, respectively. Contact alone with phloxine B caused no mortality. When exposure was assessed using spheres coated with a latex paint mixture containing sucrose and formulated dimethoate (Digon 400 EC) or imidacloprid (Provado 1.6 F) at concentrations ranging from 5 to 70 g (AI)/cm2, both insecticides showed reduced effectiveness compared with toxicities from glass jar tests, with Digon two times more toxic than Provado. After exposure to artificial rainfall and retreatment with sucrose, Digon- and Provado-treated spheres exhibited greatest residual effectiveness, with diazinon-treated spheres less effective. Spheres treated with formulated abamectin (Agri-Mek 0.15 EC) at 1.0% (AI) performed only slightly better than phloxine B-treated spheres, which completely lost effectiveness after exposure to rainfall. Spheres treated with formulated imidacloprid (Merit 75 WP) at 1.5% (AI) showed equal or better residual efficacy in killing apple maggot flies (> 80% mortality, shorter lethal duration of feeding) over a 12-wk exposure period to outdoor weather than spheres treated with Digon at 1.0% (AI) after both types were retreated with sucrose. Our results indicate that imidacloprid is a promising safe substitute for dimethoate as a fly killing agent on lure-kill spheres. Imidacloprid formulated as Merit 75 WP had greater residual efficacy than imidacloprid formulated as Provado 1.6 F.     

Effect of the pH of the lysing solution on the sedimentation properties of the nucleoid of intact and irradiated Ehrlich ascites tumor cells

A study was made of the sedimentation properties of Ehrlich ascites tumor cell nucleotide obtained by cell lysis in 1.95 M NaCl, 0.1 M EDTA, 0.02 M tris, and 0.5% triton X-100, at pH 5.0 and 8.0. It was shown that the nucleotide obtained at pH 5.0 has a more compact structure than that obtained at pH 8.0. Irradiation of cells leads to relaxation of the nucleotide decreasing the rate of its sedimentation in a neutral sucrose gradient. The influence of irradiation on the sedimentation properties is more pronounced with pH 5.0 than 8.0.     

pH-dependent stability of EGX, a multi-functional cellulase from mollusca, Ampullaria crossean

Cellulose and hemicellulose are the most abundant andmajor constituents of plants and the potential rawmaterials for enzyme hydrolysis related biotechnologicalprocesses. The cellulase and hemicellulase have beenconsidered as two of the most important enzymes inbiotechnology market which can hydrolyze cellulosic ma-terials to fermentable sugars for various biotechnologicalpurposes [1,2], and can also be used in textile- and paper-making industry [3]. It is important to use these enzymesunder re…     

Nectar intake of white-bellied sunbirds (Cinnyris talatala): can meal size be inferred from feeding duration?

A positive relationship between feeding duration and meal size of avian nectarivores has often been assumed in earlier studies. We investigated whether feeding duration can be used as a surrogate for the amount of sugar solution ingested by white-bellied sunbirds, Cinnyris (Nectarinia) talatala. Feeding durations of sunbirds consuming three sucrose concentrations (10%, 20%, and 40% w/w) were measured using an infrared photodetection system, and the amounts consumed were recorded simultaneously by weighing the feeder throughout the experiment. For all three diet concentrations, a positive relationship was found between the time spent feeding per 30 min and the mass consumed. Therefore, feeding duration is demonstrated to be an index of the amount ingested on a particular sugar concentration. The rate of ingestion, however, depended on the sugar concentration, with the highest rate at the lowest concentration of 10% and the lowest rate at the 40% concentration. Less total time was spent feeding on the 20% solution than on the 10% solution, but time increased on the 40% diet because of viscosity effects. There appeared to be a weak relationship between feeding patterns and sex, but this was not significant, probably because of interindividual variation.     

Effects of different saccharose and electrolyte concentrations on preserved erythrocytes

Preservation solutions for buffy coat-free red cell concentrates with sucrose concentrations from 234 decreasing up to 15 mmol per 1 solution were tested. The hemolysis rate increased from 0.5 up to 1.9% by decreasing the sucrose concentration. The red cell volume was unchanged at low sucrose concentrations. No differences were noticed in ATP content and morphological changes. A considerable extracellular pH shift at high sucrose concentration exists only at the beginning of storage. A sucrose concentration of 30-50 mmol/l solution (3-5 mmol per unit red cell concentrate) at an ionic strength of 0.16 proves to be most suitable.     

Amphetamine and Reserpine Deplete Brain Biogenic Amines and Alter Blow Fly Feeding Behavior

HPLC with electrochemical detection was used to determine the levels of p-hydroxyphenylethanolamine (octopamine), 3,4-dihydroxyphenylethylamine (dopamine), and 5-hydroxytryptamine (5-HT) in the brains of control, reserpine, and d-amphetamine-treated blow flies, Phormia regina Meigen. Parallel studies were carried out to assess the effects of the two drugs on fly feeding behavior, measured as mean acceptance threshold: the minimum sucrose concentration to which the average fly in a population will respond by proboscis extension when its tarsi contact the solution. In saline-injected control flies, all three amines were found at levels of approximately 2 pmol/brain. Thirty minutes after injection with d-amphetamine (12 micrograms/fly), brain octopamine was depleted by 85%, whereas dopamine and 5-HT were depleted by 70%. Reserpine (5 micrograms/fly) caused 70% depletion of dopamine and greater than 90% depletion of both octopamine and 5-HT 24 h after injection. However, the effect of reserpine was much slower in onset (hours versus minutes) and more persistent (days versus hours) than was the effect of d-amphetamine. With either drug, the time course of amine depletion closely matched the time course of the increase in feeding threshold observed in drug-treated flies. These results suggest that CNS pools of the biogenic amines, octopamine, dopamine, and 5-HT are important in governing blow fly responsiveness to food stimuli.     

Effects of nectar concentration on butterfly feeding: measured feeding rates for Thymelicus lineola (Lepidoptera: Hesperiidae) and a general feeding model for adult Lepidoptera

Summary Field observations of the adult European skipper, Thymelicus lineola (Ochs), feeding on concentrated nectars (40–65% sucrose) from a variety of flower species led us to question recent literature stating that butterflies feed primarily, and most effectively, on dilute nectars. Rate of sucrose solution intake, volume consumed and feeding duration were measured for males and females at 25 and 35°C under laboratory conditions. As sucrose concentration increased, the volume of solution ingested per meal first increased and then decreased gradually, while sucrose intake was highest at concentrations 40%. Females fed more than males at all concentrations >10% while temperature had no significant effect on meal size. Feeding duration increased with concentration, was shorter at 35 than at 25°C, and was longer for females than males.The rate of volume intake decreased as concentration incresed, but not nearly as rapidly as predicted by earlier models. Rates did not differ between the sexes but were faster at 35 than 25°C. This increase was contributed to equally by a reduction in viscosity and an increase in power output of the cibarial pump. The form of the relations was similar, with maximum rate of sucrose intake occurring at 40% sucrose.A new mathematical model was developed to describe the rate — concentration relation based on the Hagen-Poiseuille equation for laminar fluid flow through pipes. Our model differs from previous models principally in that the power output of the insect's cibarial pump remains relatively constant while the pressure drop created by the pump to induce suction is highly variable. This change results in a very different feeding rate — sucrose concentration function with the optimal rate of sucrose intake at a concentration of approximately 40%. The model indicates that the same relation should hold for a wide range of proboscis shape and size and type of suction pump, and should therefore be applicable to all other nectar feeders with sucking mouth parts. Independent verifications of the model were carried out by measuring the rate of uptake of sucrose solutions of the adult common armyworm, Pseudaletia unipuncta (Haw.), and of human subjects using a volumetric pipette, both of which gave an excellent fit.Nectar concentrations which correspond to optimal rates of sucrose intake should be highly preferred by insects with high feeding costs, those which are time-limited, or which are very vulnerable while feeding. High transport costs and severe water stress may shift preferences to higher and lower concentrations respectively.     

Host acceptance behaviour of the jack pine tip beetle, Conophthorus anksianae and the red pine cone beetle, C. resinosae

The jack pine tip beetle, Conophthorus banksianae McPherson (Coleoptera: Scolytidae) and the red pine cone beetle, C. resinosae Hopkins, are doubtful sibling species. However, it is possible that these two taxa are valid species that maintain reproductive isolation because they accept different hosts. In a series of laboratory and field cage experiments, the host acceptance behaviours of these two species under choice and no choice conditions were compared. The field experiments demonstrated that the two species have a similar propensity to accept jack pine cones and shoots for feeding, but differ consistently in their acceptance of red pine cones, and variably in their acceptance of red pine shoots. However, the laboratory experiments did not indicate a difference between the two species in their propensity to accept red pine cones for feeding. In field cages, C. resinosae accepted significantly more red pine cones for oviposition than C. banksianae; the situation was reversed for jack pine shoots. In comparison to C. banksianae, C. resinosae is a more generalist feeder. The results from this study suggest that host acceptance behaviour is a permeable barrier unable to ensure reproductive isolation between the two species. Although there are differences in the host acceptance behaviours between C. banksianae and C. resinosae, we conclude that these differences do not necessarily support their designation as distinct species.     

Effect of initial pH independent of operational pH on hydrogen fermentation of food waste

The effect of initial pH from 5.0 to 9.0 on H₂ fermentation of food waste was investigated. In this batch experiment, however, unlike previous studies for initial pH, operational pH was maintained at 5.0 by the addition of alkaline solution. Although the period for pH drop from the initial values to 5.0 was less than one-tenth of the entire fermentation, this short period significantly affected the H₂ production performance. At initial pH 6.0-9.0, successful H₂ yield of 1.3-1.9 mol H₂/mol hexose_added was achieved with a peak value at pH 8.0. The H₂ yield achieved at initial pH 8.0 was corresponded to the 8.13% of total energy content in the substrate. At initial pH 5.0, the smallest butyrate production, but the highest ethanol production was detected, indicating unfavorable conditions for H₂ production. There was no significant relationship between total required amount of alkaline solution and initial pH values.     

Role of water in the energy of hydrolysis of phosphoanhydride and phosphoester bonds

The observed equilibrium constants for hydrolysis (Kobs) of a phosphoester and a phosphoanhydride bond were measured under a variety of conditions likely to alter the interactions of reactants and products with water. These included increasing the pH of the medium from 5.0 to 10.0, increasing the MgCl2 concentration form 0 to 200 mM, and decreasing the water activity of the medium by adding either dimethyl sulfoxide (50%, v/v) or polyethylene glycol 6,000-8,000 (50%, w/v). The Kobs for phosphoesters such as phosphoserine, glucose phosphate, glycerol phosphate, and ethylene glycol phosphate varied little over this wide range of conditions, the extreme values of Kobs being 12 and 200 M. In contrast, the Kobs for the phosphoanhydride bond of pyrophosphate varied from a value greater than 20,000 to 0.1 M. In totally aqueous media at a pH between 7.0 and 8.0 and in the presence of 0.5-1.0 mM MgCl2, the energy of hydrolysis of pyrophosphate was 1.2-4.0 kcal/mol greater than that of phosphoserine. However, when the water activity was decreased by adding polyethylene glycol to the medium within the same pH and MgCl2 concentration range, the energy of hydrolysis of phosphoserine became 2.0-2.5 kcal/mol greater than that of pyrophosphate. The results suggest that for phosphoesters, the solvation energies of reactants and products, unlike the case of phosphoanhydride bonds, are not the major factors in determining the energy of hydrolysis.     

A study of factors affecting the sensitivity of the passive haemagglutination method for serotyping Campylobacter jejuni and Campylobacter coli and recommendations for a more rapid procedure

Factors affecting the sensitivity of the passive haemagglutination method for serotyping campylobacters have been studied. The concentration of red blood cells during the haemagglutination stage of the procedure markedly affected the titer obtained. An increase in concentration of red blood cells resulted in a lower titer, with titers being inversely proportional to red blood cell concentration. No differences in titer were observed when erythrocytes were sensitized at a range of pH values between pH 5.0 and pH 8.0. The time required for antigen extraction and for red blood cell sensitization was shown to be 15 min each, thus resulting in a reduction in the time required for serotyping. Furthermore, use of avian erythrocytes enabled the haemagglutination reactions to be read after incubation for only 1 h. Combining these procedures with a rapid slide haemagglutination test enables a single worker to serotype over 100 C. jejuni and C. coli isolates within 1 working day.     

Capillary electrophoresis method for simultaneous determination of penicillin G, procaine and dihydrostreptomycin in veterinary drugs

Capillary electrophoresis method for identification and simultaneous determination of procaine, dihydrostreptomycin and penicillin G, present in multiantibiotic veterinary preparations, was elaborated. The influence of pH (5.0-9.75) and concentration of disodium tetraborate decahydrate in running buffers (0.02-0.1 M) as well as temperatures (25-40 degrees C) on separation efficacy were analyzed. For quantitative analysis, 0.08 M borate buffer (pH 8.0) at 35 degrees C and 15 kV were chosen. Method was validated, selectivity, precision, linearity, LOD, LOQ, accuracy and specificity of capillary zone electrophoresis (CZE) were evaluated.     

Interacting effects of time,temperature, pH and simple sugars on biomass and toxic metabolite production by three Alternaria spp.

Biomass and toxic metabolite production by Altemaria hemicota, A. solani and A. tenuis in modified Czapek Dox broth (mCDB) as affected by incubation time (up to 4 wk) temperature (6, 15 and 25 °C), pH (3.0, 5.0 and 8.0) and sugars (glucose, fructose and sucrose) was studied. Biomass production was greatest at 25 ° C and pH 8.0 but toxin production was enhanced at 15 °C. In general, biomass production was promoted by up to 9% glucose and sucrose and 6% fructose; however, toxin production was simultaneously reduced by elevated sugars in mCDB over a 4-wk incubation period.     

Comparison of neonicotinoid insecticides for use with biodegradable and wooden spheres for control of key Rhagoletis species (Diptera: Tephritidae).

Field-based studies and laboratory bioassays were conducted with apple maggot, Rhagoletis pomonella (Walsh), and blueberry maggot, Rhgoletis mendax Curran, flies to investigate the performance and duration of activity of insecticide-treated biodegradable and wooden spheres for control of Rhagoletis species. Four neonicotinoid insecticide treatments including imidacloprid, thiamethoxam, and thiocloprid at 2% (AI) were evaluated with biodegradable spheres. In 1999, significantly more apple maggot flies were found killed by imidacloprid-treated spheres compared with thiamethoxam-treated spheres during early and late season. In 2000, spheres treated with either of two formulations of imidacloprid killed significantly more apple maggot flies compared with thiamethoxam, thiocloprid, and untreated spheres. In blueberries, there were no significant differences between the numbers of blueberry maggot flies killed by both imidacloprid-treated or thiamethoxam-treated spheres in 1999. However, during the 2000 blueberry field season, both formulations of imidacloprid were significantly more effective in killing blueberry maggot flies compared with spheres treated with thiamethoxam, thiocloprid and untreated controls. Overall, spheres treated with thiocloprid were ineffective and did not kill significantly more apple maggot or blueberry maggot flies compared with the controls. Laboratory bioassays showed that the effectiveness of field-exposed spheres treated with imidacloprid at 4 and d 8% (AI) and thiamethoxam at 4% (AI) in killing apple maggot flies was not significantly reduced over a 12-wk aging period. Additionally, wooden spheres aged outdoors for 12 wk with and without mold maintained residual activity in laboratory tests, whereas biodegradable spheres of equal aging, with and without mold lost their effectiveness in killing apple maggot flies. In other studies, we confirmed that the addition of an external feeding stimulant (sucrose) significantly increases the effectiveness of both biodegradable and wooden spheres treated with imidacloprid at 2% (AI).     

Magnitude of the proton moving force of Staphylococcus aureus cells and features of the interaction of staphylococci with phages

The magnitude of the transmembrane electrical potential difference and the proton gradient across the energy-transducing membrane of Staphylococcus aureus were determined. The delta psi value was shown to rise from 100 to 160 mV upon alkalinization of the medium within the pH range of 5.0-8.0; at the same time, the pH value dropped from 90 to 40 mV. The proton motive force magnitude remained within the range of 191-198 mV at the pH values under study. Membrane potential generation took place, when the respiratory chain and H+-ATPase were operative. An addition of phages to cell suspensions resulted in a decrease of the membrane potential magnitude. Phage infection was effectively suppressed by inhibitors which affect the proton motive force generation in cell membranes of staphylococci.