Rapid time-resolved immunofluorometric assay for the measurement of creatine kinase in serum and whole blood samples

A rapid and simple immunochemical method was developed for the assessment of the creatine kinase (MM) isoenzyme [CK(MM)], a protein marker linked with animal welfare and meat quality. The one-step time-resolved immunofluorometric assay produced quantitative results from serum or whole blood samples in 20 min. The analytical limit of detection (mean + 2s) for the immunoassay was 17 ng/mL (n = 6), and the functional limit of detection for the analysis of porcine whole blood samples was 426 ng/mL (n = 24). The working range of the method was linear up to 50 micro g/mL, and the within-assay precision varied between 2.1 and 10.9%. The analysis of porcine serum samples showed that the results from the immunoassay method and colorimetric CK enzyme activity determination were highly correlated (r(2) = 0.965, n = 17, p < 0.001). The practicability of the assay was demonstrated by the analysis of 300 porcine whole blood samples in a slaughterhouse environment.     

Influence of soil and host plant crop on the genetic diversity of Azospirillum amazonense isolates

The genetic structure of Azospirillum amazonense populations isolated from the rhizosphere soil and washed and surface-sterilised roots of rice, maize and sorghum plants, cropped simultaneously in two different soils (clay loam and sandy loam) was characterised. Genetic diversity was measured by restriction fragment length polymorphism of the amplified 16S–23S rDNA intergenic spacer region (RISA-RFLP) and cluster analysis. Four genetically distinct clusters of isolates were observed with 78% similarity, suggesting that the A. amazonense population was heterogeneous at the strain level regardless of the soil type or host plant. Analysis of molecular variance (AMOVA) demonstrated that the host plant had a highly significant selective effect on the genetic structure of this species, especially on those isolates intimately associated with them, but also to a lesser extent on isolates from the rhizosphere and washed roots. The soil type also had a highly significant selective effect on A. amazonense genetic diversity, especially for those isolates from the rhizosphere soil. The selective effect of the soil type combined with that of the host plant suggests that environmental factors, such as soil texture and composition of exudates provided by C₃ or C₄ plants, play major roles in the overall genetic structure of A. amazonense populations associated with these cereals.     

A simplified procedure for terminal restriction fragment length polymorphism analysis of the soil bacterial community to study the effects of pesticides on the soil microflora using 4,6-dinitroorthocresol as a test case

We have studied the structural effects of application to the soil of a potentially detrimental herbicide, 4,6-dinitroorthocresol (DNOC) by analysing amplified ribosomal DNA restriction analysis (ARDRA) and terminal restriction fragment length polymorphism (T-RFLP) signatures of 16S rDNA fragments of culturable bacterial communities isolated from diluted soil suspensions. This approach has the potential to reveal changes induced by stressing the soil microflora with DNOC. This paper shows that, whereas only few changes of the ARDRA and T-RFLP profiles result from ageing of the soil, treatment of the soil with DNOC induces major modifications of these profiles. Therefore, for the practical purpose of pesticide registration, ARDRA and T-RFLP analysis performed on the dominant culturable fraction of the soil bacteria, implemented using conventional gel electrophoresis, offers the means of a routine, simple and meaningful test for detecting some of the changes affecting the structure of the soil microflora in response to pesticide application.     

MHPG excretion in depressive disorders: relation to clinical subtypes and desynchronized sleep

The urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) was significantly lower in patients with manic-depressive depressions than in patients with chronic characterological depressions. There was an inverse relationship between MHPG excretion and the amount of time spent in desynchronized sleep, particularly in the manic-depressive disorders. Excretion of MHPG was not related to the degree of retardation, agitation, or anxiety in these patients.     

Exchange of conduction pathways between two related K+ channels

The structure of the ion conduction pathway or pore of voltage-gated ion channels is unknown, although the linker between the membrane spanning segments S5 and S6 has been suggested to form part of the pore in potassium channels. To test whether this region controls potassium channel conduction, a 21-amino acid segment of the S5-S6 linker was transplanted from the voltage-activated potassium channel NGK2 to another potassium channel DRK1, which has very different pore properties. In the resulting chimeric channel, the single channel conductance and blockade by external and internal tetraethylammonium (TEA) ion were characteristic of the donor NGK2 channel. Thus, this 21-amino acid segment controls the essential biophysical properties of the pore and may form the conduction pathway of these potassium channels.     

The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions

Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. Both of these conditions are produced within the stratospheric winter polar vortex. Recent aircraft missions have provided new information about the structure of polar vortices during winter and their relation to polar ozone depletions. The aircraft data show that gradients of potential vorticity and the concentration of conservative trace species are large at the transition from mid-latitude to polar air. The presence of such sharp gradients at the boundary of polar air implies that the inward mixing of heat and constituents is strongly inhibited and that the perturbed polar stratospheric chemistry associated with the ozone hole is isolated from the rest of the stratosphere until the vortex breaks up in late spring. The overall size of the polar vortex thus limits the maximum areal coverage of the annual polar ozone depletions. Because it appears that this limit has not been reached for the Antarctic depletions, the possibility of future increases in the size of the Antarctic ozone hole is left open. In the Northern Hemisphere, the smaller vortex and the more restricted region of cold temperatures suggest that this region has a smaller theoretical maximum for column ozone depletion, about 40 percent of the currently observed change in the Antarctic ozone column in spring.     

Water Availability for Winter Wheat Affected by Summer Fallow Tillage Practices in Slope Dryland

The tillage experiments for winter wheat were conducted on the slope farmland in Luoyang,Henan Province in the semihumid to arid loess plateau areas of North China. Different tillage methods inclu-ding reduced tillage (RT), no-till (NT), 2 crops/year (2C), subsoiling(SS), and conventional tillage (CT)were compared to determine the effects of tillage methods on soil water conservation, water availability, andwheat yields in a search for better farming systems in the areas. The NT and SS showed good effects on waterconservation. The soil water storage increased 12 - 33 mm with NT and 9 - 24 mm with SS at the end of sum-mer fallow periods. The soil evaporation with NT and SS decreased 7 - 8 mm and 34 - 36 mm during the fallowperiods of 1999 and 2001, respectively. Evapotranspiration (ET) with NT and SS increased about 47 mm dur-ing wheat growth periods of 2000 to 2001. Treatment RT and 2C had low water storage and high water lossesduring the fallow periods. The winter wheat yields with conservation tillage practices were improved in the 2ndyear, increased by 3, 5 and 8 % with RT, NT and SS, respectively, compared with CT. The highest wheatyields were obtained with subsoiling, and the maximum economic benefits from no-till. All conservation tillagepractices provided great benefits to saving energy and labors, reducing operation inputs, and increasing eco-nomic returns. No-till and subsoiling have shown promise in increasing water storage, reducing water loss, en-hancing water availability, and saving energy, as well as increasing wheat yield.     

Oxidation-resistant gold-55 clusters

Gold nanoparticles ranging in diameter from 1 to 8 nanometers were prepared on top of silicon wafers in order to study the size dependence of their oxidation behavior when exposed to atomic oxygen. X-ray photoelectron spectroscopy showed a maximum oxidation resistance for "magic-number" clusters containing 55 gold atoms. This inertness is not related to electron confinement leading to a size-induced metal-to-insulator transition, but rather seems to be linked to the closed-shell structure of such magic clusters. The result additionally suggests that gold-55 clusters may act as especially effective oxidation catalysts, such as for oxidizing carbon monoxide.     

Mariner 9 television reconnaissance of Mars and its satellites: preliminary results

At orbit insertion on 14 November 1971 the Martian surface was largely obscured by a dust haze with an extinction optical depth that ranged from near unity in the south polar region to probably greater than 2 over most of the planet. The only features clearly visible were the south polar cap, one dark, spot in Nix Olympica, and three dark spots in the Tharsis region. During the third week the atmosphere began to clear and surface visibility improved, but contrasts remained a fraction of their normal value. Each of the dark spots that apparently protrude through most of the dust-filled atmosphere has a crater or crater complex in its center. The craters are rimless and have featureless floors that, in the crater complexes, are at different levels. The largest crater within the southernmost spot is approximately 100 kilometers wide. The craters apparently were formed by subsidence and resemble terrestrial calderas. The south polar cap has a regular margin, suggsting very flat topography. Two craters outside the cap have frost on their floors; an apparent crater rim within the cap is frost free, indicating preferentia loss of frost from elevated ground. If this is so then the curvilinear streaks, which were frost covered in 1969 and are now clear of frost, may be low-relief ridges. Closeup pictures of Phobos and Deimos show that Phobos is about 25 +/-5 by 21 +/-1 kilometers and Deimos is about 13.5 +/- 2 by 12.0 +/-0.5 kilometers. Both have irregular shapes and are highly cratered, with some craters showing raised rims. The satellites are dark objects with geometric albedos of 0.05.