UV‐B radiation constrains the photosynthesis of Quercus robur through impacts on the abundance of Microsphaera alphitoides

Quercus robur saplings were exposed at an outdoor facility in the UK to supplemental levels of UV‐B radiation (280–315 nm) under arrays of cellulose diacetate‐filtered fluorescent lamps which also produced UV‐A radiation (315–400 nm). Saplings were also exposed to supplemental UV‐A radiation under arrays of polyester‐filtered lamps and to ambient levels of solar radiation under arrays of unenergized lamps. The UV‐B treatment was modulated to maintain a 30% elevation above the ambient level of erythemally weighted UV‐B radiation. Naturally occurring infections by oak powdery mildew (Microsphaera alphitoides) were more abundant, and developed more rapidly, on lammas leaves of saplings which were exposed to treatment levels of UV‐B radiation than on leaves of saplings exposed to supplemental UV‐A or to ambient levels of solar radiation over 12 weeks in summer and autumn 1996. An analysis of leaf photosynthetic capacities revealed that M. alphitoides infection reduced the quantum efficiency of photosystem (PS) II by 14% at moderate irradiance. Although there was no direct effect of UV‐B radiation on PSII photochemistry, exposure of saplings to supplemental UV‐A radiation under polyester‐filtered lamps resulted in a 17.5% decrease in PSII quantum efficiency, compared with saplings exposed to ambient solar radiation. The results from our study suggest that photosynthesis of Q. robur may be constrained by exposure to UV‐B radiation in the natural environment through impacts on the abundance of M. alphitoides.     

Fractional composition of redox systems in the soils of coal mine dumps

Specific features of the development of redox systems in the soils of coal mine dumps in Kemerovo oblast were studied. The quantitative characteristics of the fractional composition of the oxidized and reduced components in these soils were obtained, and their heterogeneity was shown. Distribution patterns of the reduced and oxidized components in the parent material of these specific technogenic landscapes in the course of soil evolution were revealed.     

Dominance relationships between S-alleles in the stigmas of Brussels sprouts (Brassica oleracea var. Gemmifera)

Summary Partial dominance between S-alleles in the stigma was found to be common in 412 plants of Brussels sprouts in which two S-alleles could be detected. Amongst a further 168 plants in which only one S-allele could be detected, 5 plants showed the detected allele to be completely dominant to the other allele present, but further examples are expected. Dominance relationships are given for 34 pairs of S-alleles representing 16 different S-alleles. The most recessive S-alleles in the stigma appear to be S5, S14, S15 and S45, while the most dominant are S23, S29, S35, S36 and S39. The significance of dominance between S-alleles in connection with the breeding system of Brussels sprouts is discussed, and an explanation proposed for the high frequency of S2 based on its unusual dominance behaviour.     

Rapid method of determining pollen incompatibility in Chrysanthemum morifolium Ramat

Summary A classification system for predicting high, medium and low seed set from Chrysanthemum morifolium crosses was developed. Stigmas collected and preserved 8 days after pollination were examined with a binocular microscope for adhering pollen grains. Florets from compatible crosses had brown stigmas with pollen grains attached and embryo development while florets from incompatible crosses had white stigmas with no or rarely 1 or 2 pollen grains attached and no embryo development. Using this method the occurrence of seed set was predicted with 78.5% accuracy in one year and 89% in the following. This provides a method of determining the compatibility of a chrysanthemum cross without waiting the 1 to 2 months required for seed ripening.Scientific Journal Series Paper Number 7570 of the Minnesota Agricultural Experiment Station.     

The effects of increasing sodium chloride concentration on Mycoplasma gallisepticum vaccine survival in solution

Lyophilized Mycoplasma gallisepticum (MG) vaccines are generally rehydrated and diluted with distilled or chlorine-free water as per manufacturer recommendations. However, as mycoplasma species lack a cell wall, this can lead to decreased viability of live vaccine during administration. The ability of phosphate-buffered saline (PBS) to prevent losses in live vaccine viability was examined. It was shown that a concentration of 1 x PBS prevented the two-fourfold decrease in MG viability seen when the vaccines were diluted with water alone.     

Pathological fractures secondary to metaphyseal osteopathy in a dog.

A four-month-old German Shepherd Dog (GSD) was admitted with bilateral non-weight bearing hindlimb lameness and pyrexia. A diagnosis of bilateral distal femoral fractures secondary to metaphyseal osteopathy was made on the basis of clinical signs, radiography and biopsy. The dog returned to normal function following conservative management. As far as the authors are aware there are no previous reports of pathological fractures secondary to this condition.