Immobilization and utilization of the recombinant fusion proteins trypsin-streptavidin and streptavidin-transglutaminase for modification of whey protein isolate functionality     

Wilcox CP  Clare DA  Valentine VW  Swaisgood HE 《Journal of agricultural and food chemistry》2002,50(13):3723-3730

A method was developed for the production of a hydrolyzed/polymerized whey protein derivative with altered solution and gelation properties using a combination of recombinant DNA and immobilized enzyme technologies. The recombinant fusion proteins trypsin-streptavidin (TrypSA) and streptavidin-transglutaminase (cSAcTG) were produced in Escherichia coli, extracted, and then immobilized by selective adsorption on biotinylated controlled-pore glass. Recirculation through a TrypSA reactor induced limited proteolysis of whey proteins. Hydrolysates were then recirculated through a cSAcTG reactor for incremental periods of time to arrive at increasing degrees of polymerization. The polymers were subsequently analyzed for viscosity/flow behavior, gelation properties, and fracture properties using shear rate ramps/intrinsic viscosity, small-strain oscillatory rheology, and vane viscometry, respectively. By combining limited proteolysis with controlled cross-linking, it was possible to create derivatives of whey proteins with enhanced functional properties. Increases in the degree of whey protein modification were correlated with greater apparent viscosity and intrinsic viscosity, lowered gel point temperatures, and stronger, more brittle gels. This method allowed for recycling of the enzyme, eliminated the requirement for a downstream inactivation step, and permitted control over the extent of modification. Utilization of a similar process may allow for the production of designer proteins engineered with specific functionalities.  相似文献   

Synthesis of haptens and development of an immunoassay for the olive fruit fly pheromone     

Neokosmidi A  Ragoussis V  Zikos C  Paravatou-Petsotas M  Livaniou E  Ragoussis N  Evangelatos G 《Journal of agricultural and food chemistry》2004,52(14):4368-4374

An enzyme-linked immunosorbent assay (ELISA) for the olive fruit fly pheromone, Bactrocera oleae Gmelin, was developed. The assay uses polyclonal antibodies, raised in rabbits, against (+/-)-beta-[3-(1,7-dioxaspiro[5.5]undecane)]propionic acid, 2 (hapten I), conjugated to the KLH (keyhole limpet hemocyanin) by the carbodiimide method. A second hapten, (+/-)-delta-[3-(1,7-dioxaspiro[5.5]undecane)]butylamine, 3 (hapten II), after conjugation to a biotin moiety, was used for indirect immobilization onto ELISA microwells precoated with the glycoprotein avidin. The developed ELISA method measures the synthetic olive fruit fly pheromone in concentrations ranging between 0.08 and 10 microg/mL and shows great promise for practical applications for pheromone detection in environmental and biological samples. The results obtained strongly indicate that this technique, to our knowledge the first insect pheromone enzyme-linked immunosorbent assay so far reported, is a fast, sensitive, inexpensive, and highly convenient method for the analysis of a volatile and low molecular weight compound such as 1,7-dioxaspiro[5.5]undecane, 1.  相似文献   

Edge effects in line intersect sampling with segmented transects     

David?L.?R.?AffleckEmail author  Timothy?G.?Gregoire  Harry?T.?Valentine 《Journal of Agricultural, Biological & Environmental Statistics》2005,10(4):460-477

Transects consisting of multiple, connected segments with a prescribed configuration are commonly used in ecological applications of line intersect sampling. The transect configuration has implications for the probability with which population elements are selected and for how the selection probabilities can be modified by the boundary of the tract being sampled. As such, the transect configuration also affects the performance of methods designed to eliminate edge-effect bias. We show that the reflection method solves the edge-problem for designs that use symmetric radial transects (e.g., straight-line and X-shaped transects centered at the sample point). This method also applies to designs that use asymmetric radial transects, provided the orientation is selected uniformly at random. Asymmetric radial transects include straight lines emanating from the sample point, and L- and Y-shaped transects. The reflection method does not apply to designs where polygonal transects (e.g., triangular, square, and hexagonal transects) are used, or where the orientations of asymmetric radial transects are fixed. We provide a new method that eliminates edge-effect bias for designs that use asymmetric radial transects with fixed orientation, but a workable solution for polygonal transects remains elusive.  相似文献   

Processing Affects the Physicochemical Properties of Fiber from Wheat and Flax in Ready‐to‐Eat (RTE) Flaked Cereal     

David W. Lafond  YuLai Jin  KiYul Cho  Dale R. Romsos 《Cereal Chemistry》2015,92(5):497-503

Fiber from wheat and flax is mostly insoluble, making addition in high amounts to a food difficult without adversely affecting product attributes. One approach to increasing the level of these fibers in food is to hydrolyze fiber to more soluble forms through processing. This study was designed to evaluate the impact of a steam pressure cooking process on physicochemical properties of ready‐to‐eat (RTE) cereal with 17.7% added unhydrolyzed flax fiber (a combination of arabinoxylans, rhamnogalacturonans, and pectins) or 15.4% added hydrolyzed wheat fiber (a purified arabinoxylan extract). Peak molecular weights of unhydrolyzed and hydrolyzed fibers were ∼2.9 × 10⁶ and ∼800 g/mol, respectively, with a ∼400‐fold higher viscosity for unhydrolyzed fiber. Molecular weight of the unhydrolyzed fiber ingredient was reduced to approximately the molecular weight of the hydrolyzed fiber as a result of the low‐shear steam pressure cooking process used, and consistent with molecular weight results, there was only a twofold difference in viscosity of the cereal remaining. The low‐fiber control RTE cereal had the highest viscosity owing to starch content.  相似文献   

In vitro characteristics of normal and dystrophic skeletal muscle from dogs     

B A Valentine  S K Chandler  J F Cummings  B J Cooper 《American journal of veterinary research》1991,52(1):104-107

Explants were prepared from skeletal muscle tissue from 5 nondystrophic pups and from 5 pups with X-linked muscular dystrophy; pups were 2 to 17 weeks old. A serial reexplant method resulted in optimal cell density with minimal fibroblast growth. Cultures were examined daily by use of phase-contrast microscopy; differentiated (post-fusion) cultures were examined by electron microscopy. Moderate nuclear pleomorphism and cell clustering were observed in cultures of normal and dystrophic muscle cells. Cultures were maintained to 27 days after plating. Minimal myofilament synthesis was observed in multinucleate cells from nondystrophic and dystrophic pups, but spontaneous contraction of myotubes was not observed during this period. Differences in growth, fusion, or differentiation of myogenic cells into multinucleate cells and myotubes were not found between dystrophic and normal muscle.  相似文献   

COMPARTMENT SYNDROME IN A LABRADOR RETRIEVER     

Jamie  Williams  MS  DVM  Michael Q.  Bailey  DVM  Eric R.  Schertel  DVM  PHD  Amy  Valentine  MS  DVM 《Veterinary radiology & ultrasound》1993,34(4):244-248

Compartment syndrome is an elevation of interstitial pressure in a closed osseofascial compartment that results in microvascular compromise. This report documents a clinical syndrome in the crus of a fourteen-month-old intact male Labrador Retriever which was consistent with trauma-induced compartment syndrome. A six month history of recurring trauma or complications resulted in the need for referral. Survey radiography and ultrasonography aided in the diagnosis, but the definitive answer was provided by femoral angiography. The patient was successfully treated and was discharged with normal limb function. One year later, there were no complications observed. Compartment syndrome is not uncommon in humans, and is routinely considered in certain blunt and most penetrating traumas. However, few reports of this complication in animals are found.  相似文献   

Omentalization of the thorax for treatment of idiopathic chylothorax with constrictive pleuritis in a cat.     

Elizabeth Lafond  Walter E Weirich  S Kathleen Salisbury 《Journal of the American Animal Hospital Association》2002,38(1):74-78

A 6-year-old, spayed female Himalayan cat with idiopathic chylothorax, which failed to respond to medical management, was successfully treated by advancement of the omentum into the thorax. Exploratory thoracotomy revealed severe, constrictive pleuritis as a sequela to chylothorax. Because of the poor prognosis for recovery from chylothorax in cats with thoracic duct ligation alone, and the lack of success in performing thoracic duct ligation in this cat, the omentum was advanced into the thorax through a hole created in the diaphragm and sutured within the thoracic cavity. The cat recovered from surgery and is clinically normal 13 months postoperatively. Omental advancement may be an effective surgical management technique for this challenging disease in cats.  相似文献   

Putative Malassezia dermatitis in six goats     

Eguchi-Coe Y  Valentine BA  Gorman E  Villarroel A 《Veterinary dermatology》2011,22(6):497-501

Histopathology submissions from 28 goats with dermatological disease were identified in an archival search of pathology files. Microscopic sections of skin biopsy specimens were examined for the presence of Malassezia spp. organisms. Six cases with many Malassezia yeasts were identified histopathologically. Based on the extent of clinical disease, three cases were regarded as localized and three were generalized infections. Clinical findings included alopecia with dry seborrhoea (four cases), greasy seborrhoea (one case), and no clinical findings specific to localized Malassezia infection when concurrent bacterial infection was present (one case). Mild pruritus was reported in two cases of generalized infection. No breed predilection was apparent. Three cases were male and three were female. Malassezia dermatitis occurred in goats from 10 months to 13 years of age. Three of six cases had concurrent bacterial infection. Skin lesions resolved following topical antifungal therapy in the two goats that were treated. Histopathological findings in all cases were severe follicular and epidermal orthokeratotic hyperkeratosis with minimal epithelial change and mild superficial perivascular to interstitial nonsuppurative inflammation. Numerous budding yeasts were visible within the stratum corneum of all cases; however, Malassezia was not isolated in the three cases in which culture was attempted. Based upon these findings, the authors suggest that the diagnosis Malassezia dermatitis in goats is most likely to be made by cytological examination of skin impressions or by examination of skin biopsy samples.  相似文献   

Glowing avalanches: new research on volcanic density currents     

Valentine GA  Fisher RV 《Science (New York, N.Y.)》1993,259(5098):1130-1131

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Local nanomechanical motion of the cell wall of Saccharomyces cerevisiae     

Pelling AE  Sehati S  Gralla EB  Valentine JS  Gimzewski JK 《Science (New York, N.Y.)》2004,305(5687):1147-1150

We demonstrate that the cell wall of living Saccharomyces cerevisiae (baker's yeast) exhibits local temperature-dependent nanomechanical motion at characteristic frequencies. The periodic motions in the range of 0.8 to 1.6 kHz with amplitudes of approximately 3 nm were measured using the cantilever of an atomic force microscope (AFM). Exposure of the cells to a metabolic inhibitor causes the periodic motion to cease. From the strong frequency dependence on temperature, we derive an activation energy of 58 kJ/mol, which is consistent with the cell's metabolism involving molecular motors such as kinesin, dynein, and myosin. The magnitude of the forces observed ( approximately 10 nN) suggests concerted nanomechanical activity is operative in the cell.  相似文献