Relieving substrate limitation-soil moisture and temperature determine gross N transformation rates

A field experiment was designed with the objective to reveal the interactions between soil moisture, temperature, total, dissolved, and phosphate buffer extractable C and N, and microbial activity in the control of in situ gross N mineralization and immobilization rates in a deciduous forest. We had three alternative hypotheses to explain variations of the gross N transformations: 1) microorganisms are C limited, 2) microorganisms are N limited, or 3) neither C nor N limit the microorganisms but moisture and temperature conditions. Each hypothesis had specific criteria to be fulfilled for its acceptance. The results demonstrated that gross N transformation rates were more dependent on and variable with soil moisture and temperature than the size of the different C and N pools. The immobilization of N was dependent on the gross mineralization rate, suggesting that the production of enzymes for mineralization of organic N and the immobilization of N from the surrounding soil is disconfirmed when the intracellular N content of the microorganisms is sufficiently high. If the microorganisms are starved for N, enzyme systems involved in both the assimilation and mineralization of N are activated. The mean in situ gross N mineralization rate was two orders of magnitude higher than the natural N deposition in the area and the N addition in the NITREX experiments, meaning that a reduction in the gross N mineralization rate of about 1% would be enough to compensate for the addition of inorganic N. This decrease would hardly be detectable given the great spatial and temporal variability of N transformation rates.     

Field response of the pine sawfly Neodiprion sertifer to the pheromone (2S,3S,7S)-diprionyl acetate and its stereoisomers

All eight optical isomers of 3,7-dimethyl-2-pentadecanyl acetate (diprionyl acetate), of high optical purity (> 97.4%), were tested for a behavioural activity on male pine sawflies, Neodiprion sertifer (Geoffr.) (Hymenoptera: Diprionidae), in northern Europe. Males were strongly attracted to (2S,3S,7S)-diprionyl acetate. Addition of more than 0.1% of the (2S,3R,7R)-isomer reduced the catch and above 2% the attraction was completely inhibited. Contrary to what has been reported for North American and Japanese populations, so significant synergistic effect of small amounts of the (2S,3R,7R)-isomer could be demonstrated. The effects of addition of the other six optical isomers alone or in combinations, were also studied, but none was found to be a synergist. The (2S,3R,7S)-isomer had a weak inhibitory effect, and completely inhibited the attraction to the (2S,3S,7S)-isomer when applied in about equal amounts as the attractant. In some cases a reduction in catch was noted when other isomers were tested, but this could be attributed to the very small amounts of the inhibitory (2S,3R,7R)-isomer present in these isomers.     

Phosphoglucomutase polymorphism in Swedish horses

Polymorphism of phosphoglucomutase (PGM) in horse erythrocytes was studied by means of starch gel electrophoresis.
Three different phenotypes, F, FS and S, were found. Family data supported the genetic theory of two autosomal, codominant alleles PGM ^F and PGM ^S controlling the variation.
The gene frequencies were estimated to 0.28 and 0.72, respectively, in the North-Swedish Horse breed and to 0.13 and 0.87, respectively, in the Swedish Trotter Breed.
The probabilities of excluding a falsely assigned stallion in the PGM system were calculated to 0.16 and 0.10, respectively, in the two breeds.     

A method for simultaneous electrophoresis of four horse red cell enzyme systems

A method was developed for simultaneous electrophoresis of the enzymes 6-phos-phogluconate dehydrogenase (6-PGD), phosphoglucomutase (PGM), phospho-hexose isomerase (PHI) and acid phosphatase (AP) from horse red cells. Genetically controlled variants of PHI were discovered by this technique. The patterns obtained for 6-PGD and PGM were similar to those obtained by the original methods described for these enzymes. The AP patterns differed somewhat from those previously described in horse.     

Periodate oxidation and degradation studies on the major water-soluble arabinoxylan in rye grain

The major water-soluble arabinoxylan from rye grain has previously been shown to contain a main chain of 4-linked β- -xylopyranosyl residues in which, on average, every second is substituted at position 3 with terminal - -arabinofuranosyl residues. Periodate oxidation, reduction and fragmentation by mild acid hydrolysis produced a series of glycerol xylosides containing 4-linked xylopyranosyl residues linked at the reducing end to position 2 of glycerol. It was shown that a one-step periodate oxidation was incomplete due to the formation of relatively stable hemiacetal linkages. A sequential oxidation and reduction procedure was used to bring about complete oxidation of arabinose and unbranched xylose residues in the intact polysaccharide. Quantitative analysis of the products liberated by mild acid hydrolysis revealed the presence of glycerol xylosides with one, two or three xylose residues in the molar ratio of 1·00:0·86:0·02. The xylose residues must have originated from branched residues in the main chain of the arabinoxylan. The units or small blocks of two residues are therefore distributed mainly as isolated branched residues and not randomly as previously reported.     

Environmental contamination by vancomycin resistant enterococci (VRE) in Swedish broiler production

Background  

Vancomycin resistant enterococci are a frequent cause of nosocomial infections and their presence among farm animals is unwanted. Using media supplemented with vancomycin an increase in the proportion of samples from Swedish broilers positive for vancomycin resistant enterococci has been detected. The situation at farm level is largely unknown. The aims of this study were to obtain baseline knowledge about environmental contamination with vancomycin resistant enterococci in Swedish broiler production and the association between environmental contamination and colonisation of birds.     

Labeling with fluorescent carbocyanine dyes of cultured endothelial and smooth muscle cells by growth in dye-containing medium.

We describe a method for labeling cultured endothelial cells (ECs) and smooth muscle cells (SMCs) by letting the cells grow for three days in culture medium containing a low concentration of the fluorescent carbocyanine dyes DiI and DiO. We show that good labeling can be obtained with considerably lower concentrations (2.5 micrograms/ml) than has previously been described. With optimal concentration the labeling is very strong and seems to label all membranous structures in the cells. It was possible to clearly distinguish differentially pre-labeled cells both in coculture and seeded on denaturated vascular grafts. The cells remain fluorescent for more than seven days and may be passaged with retained proliferative capability. We suggest that DiI/DiO-labeling using dye-containing medium may be used for several cell types and is applicable in tissue culture and in the detection of implanted cells in vivo.