Relative changes in mRNA expression of angiopoietins and receptors tie in bovine corpus luteum during estrous cycle and prostaglandin F2alpha-induced luteolysis: a possible mechanism for the initiation of luteal regression     

Tanaka J  Acosta TJ  Berisha B  Tetsuka M  Matsui M  Kobayashi S  Schams D  Miyamoto A 《The Journal of reproduction and development》2004,50(6):619-626

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Comparison of the Galleria baiting technique and a direct extraction method for recovering Steinernema (Nematoda: Rhabditida) infective-stage juveniles from soil     

Sturhan D  Mrácek Z 《Folia parasitologica》2000,47(4):315-318

Forty soil samples from forests and other biotopes in Germany and the Czech Republic were studied for the presence of entomopathogenic nematodes using the Galleria bait method at the same time as a sieving-decanting method for direct extraction of infective-stage juveniles. Five Steinernema species were recovered from the samples from Germany and four species from the samples from Czechia. All five species were recovered with both methods, but the baiting technique was generally less effective and mixtures of species were frequently undetected. The direct extraction method provided quantitative estimates of infective-stage juvenile density but no information on their infectivity or on morphological characters of adults, and nematode cultures could not be established.  相似文献   

Characterization of shiga toxin-producing Escherichia coli strains isolated from calves in Poland     

Jacek Osek  Peter Gallien  Dieter Protz   《Comparative immunology, microbiology and infectious diseases》2000,23(4)

Fecal samples from 67 3–5-months-old calves with diarrhea were screened for the presence of shiga toxin-producing Escherichia coli (STEC). Several accessory virulence factors genes were also tested. Among 192 E.coli isolates tested, 15 (7.6%) were found to harbour the shiga toxin 1 or 2 (stx1 or stx2) genes. The stx2-carrying samples were further subtyped by PCR for the stx2c, stx2d, and stx2e toxin variants. It was shown that stx2-positive bacteria mainly possessed the stx2c shiga toxin type gene. The enterohemolysin (hlyA) and intimin (eae) genes were found in seven (46.7%) STEC strains whereas the cytotoxic necrotizin factor 1 and 2 or the P fimbrial genes were detected in two isolates only. This study confirmed that calves are a reservoir of STEC strains (with all pathogenicity genes) that may be virulent for humans.  相似文献   

Perfrin,a novel bacteriocin associated with netB positive Clostridium perfringens strains from broilers with necrotic enteritis     

Leen Timbermont  Lina De Smet  Filip Van Nieuwerburgh  Valeria R Parreira  Gonzalez Van Driessche  Freddy Haesebrouck  Richard Ducatelle  John Prescott  Dieter Deforce  Bart Devreese  Filip Van Immerseel 《Veterinary research》2014,45(1):40

Necrotic enteritis in broiler chickens is associated with netB positive Clostridium perfringens type A strains. It is known that C. perfringens strains isolated from outbreaks of necrotic enteritis are more capable of secreting factors inhibiting growth of other C. perfringens strains than strains isolated from the gut of healthy chickens. This characteristic could lead to extensive and selective presence of a strain that contains the genetic make-up enabling to secrete toxins that cause gut lesions. This report describes the discovery, purification, characterization and recombinant expression of a novel bacteriocin, referred to as perfrin, produced by a necrotic enteritis-associated netB-positive C. perfringens strain. Perfrin is a 11.5 kDa C-terminal fragment of a 22.9 kDa protein and showed no sequence homology to any currently known bacteriocin. The 11.5 kDa fragment can be cloned into Escherichia coli, and expression yielded an active peptide. PCR detection of the gene showed its presence in 10 netB-positive C. perfringens strains of broiler origin, and not in other C. perfringens strains tested (isolated from broilers, cattle, sheep, pigs, and humans). Perfrin and NetB are not located on the same genetic element since NetB is plasmid-encoded and perfrin is not. The bacteriocin has bactericidal activity over a wide pH-range but is thermolabile and sensitive to proteolytic digestion (trypsin, proteinase K). C. perfringens bacteriocins, such as perfrin, can be considered as an additional factor involved in the pathogenesis of necrotic enteritis in broilers.  相似文献   

Introduction of electronics into milking technology     

Dieter Ordolff   《Computers and Electronics in Agriculture》2001,30(1-3)

In countries, like the former German Democratic Republic (GDR), where ‘industrialized’ milk production in large herds was the goal to be reached, research on automation of machine milking was started more than 30 years ago. Initially, the main goal was to mechanize operations at the end of the milking process. This work finally resulted in milking devices that do not apply uniform parameters to all cows, but operate according to the milk flow obtained from the cow actually to be milked. This evolution towards ‘controlled milking’ would not have been possible without application of electricity and electronic components for sensors and control units. Also depending on the technical evolution of electronic control systems are devices for recording milk yield and for taking samples for milk analysis, which were available around the year 1980. At that time initial projects for automatic milk recording were evaluated, which had an obvious influence on further development of milk meters. The most demanding step of application of electronic control systems up to now was the introduction of automatic milking systems. Here not only application of teat cups has to be executed, it also is necessary to enable automatic checks of udder condition, milk quality and other operations which may be challenging even for trained human operators. Further evolution of electronic measurement procedures may be important for the milk-producing farmer too, especially when on-line milk analysis is to be introduced within the near future.  相似文献   

Evidence from numerical experiments for a feedback dynamo generating Mercury's magnetic field     

Heyner D  Wicht J  Gómez-Pérez N  Schmitt D  Auster HU  Glassmeier KH 《Science (New York, N.Y.)》2011,334(6063):1690-1693

The observed weakness of Mercury's magnetic field poses a long-standing puzzle to dynamo theory. Using numerical dynamo simulations, we show that it could be explained by a negative feedback between the magnetospheric and the internal magnetic fields. Without feedback, a small internal field was amplified by the dynamo process up to Earth-like values. With feedback, the field strength saturated at a much lower level, compatible with the observations at Mercury. The classical saturation mechanism via the Lorentz force was replaced by the external field impact. The resulting surface field was dominated by uneven harmonic components. This will allow the feedback model to be distinguished from other models once a more accurate field model is constructed from MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and BepiColombo data.  相似文献   

Confirmation of botulism diagnosis in Australian bird samples by ELISA and RT rtPCR     

Anne M. Masters  Dieter G. Palmer 《Journal of veterinary diagnostic investigation》2021,33(4):684

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Generation of roasted notes based on 2-acetyl-2-thiazoline and its precursor, 2-(1-hydroxyethyl)-4,5-dihydrothiazole, by combined bio and thermal approaches     

Bel Rhlid R  Fleury Y  Blank I  Fay LB  Welti DH  Arce Vera F  Juillerat MA 《Journal of agricultural and food chemistry》2002,50(8):2350-2355

Roasted notes contribute to the flavor of thermally processed foods such as meat and bread. 2-Acetyl-2-thiazoline is one of the key volatile compounds responsible for the roasted and popcorn-like aroma character. We report here on the biogeneration of flavoring preparations with intense roasted notes, which are characterized by a high content of 2-acetyl-2-thiazoline. These flavoring preparations were obtained by fermentation of cysteamine, ethyl-L-lactate, and D-glucose with baker's yeast. The precursor of 2-acetyl-2-thiazoline, 2-(1-hydroxyethyl)-4,5-dihydrothiazole, was prepared under mild conditions by microbial reduction of the carbonyl group of 2-acetyl-2-thiazoline using baker's yeast as biocatalyst. The addition of 2-(1-hydroxyethyl)-4,5-dihydrothiazole as aroma precursor to pizza dough resulted in an increase of the roasted note.  相似文献   

Phosphatbindungsformen auf einem Bergehaldenrekultivierungsversuch     

Dieter A. Hiller 《植物养料与土壤学杂志》1994,157(2):117-123

Phosphorous species in a field reclaimation experiment of a coal mining dump In the autumn of 1990 soil samples from 15 different plots of a field experiment cultivation area on a former coal mining waste heap were taken to characterize phosphorous species. In the upper 10 cm of the colliery spoil soil up to 30 % of total phosphorous is bound in the soil organic matter. The phosphate fixed in Ca phosphates is in nearly all cases below 1 % of total P. Up to 63 % of total P are accumulated as Fe and Al phosphates. The amount of water soluble phosphates is strongly reduced by the amount of hydrous iron oxides. The small amounts of lactate leachable phosphate show that P is a strong limiting factor in plant nutrition on soils of coal mining dumps. Besides the investigations showed a rapid acidification of the coal mining waste substrate which results from pyrite oxidation. Some plots of the field experiment area are acidified to pH (CaCl₂) 2.6, this is in some cases a decreasing by 4.6 pH units which is a remarkable change within 3 years.  相似文献   

Forest decline and soil nutritional problems in pacific areas     

Dieter Mueller-Dombois 《Water, air, and soil pollution》1990,54(2):195-207

Soil nutrient stresses have been determined to contribute to stand-level dieback in two Pacific forest biomes, the HawaiianMetrosideros rain forest and remnants of the eastern AustralianEucalyptus forest. In the Hawaiian dieback, low levels of N limit indigenous forest development early in primary succession on volcanic soils, while later in primary succession, stresses appear to be associated with soil aging, acidification, loss of cations, decreasing levels of P, increases in soluble Al, and, under poor drainage, sharp increases in soluble Fe. These nutrient limitations put a ceiling on stand development and growth and are considered as one of the three causes predisposing stands to dieback. In the rural or New England dieback of eastern Australia, indigenous eucalypts are adapted to ancient soils with very low levels of P, but pasture improvement with clover and fertilization with superphosphate has imposed different stresses on remnant eucalypts in pastures and nearby forest islands. After fertilization, the trees grow faster initially, but their foliage becomes highly nutritious for insects. Other factors also contribute to a build-up of insects as pests, which now threaten the remaining eucalypts. The rural dieback represents an example of how forests with low canopy species diversity, simplified structure, lack of successional species, and which are prone to dieback under natural conditions, can be destroyed by intensification of agricultural development. The paper closes with a summary of generic factors that were found to cause forest dieback under natural conditions and compares these to the anthropogenically superimposed stresses that led to aggravated tree and forest decline in the Australian rural or New England dieback. The suggestion is made that comparative dieback research at the global level will lead to an improved understanding of natural forest dynamics as an aid in interpreting the new stresses imposed on forests by human activity.  相似文献