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The response of bacteria in bulk soil and earthworm casts to carbon enrichment is analyzed by using an RNA stable-isotope probing/terminal restriction fragment length polymorphism strategy with [super 13]C-labeled glucose and acetate. The results have shown the biases that are generated by adding C substrates to detect metabolically active bacteria in soil.

One of the various ecosystemic services sustained by soil is pollutant degradation mediated by adapted soil bacteria. The pathways of atrazine biodegradation have been elucidated but in situ expression of the genes involved in atrazine degradation has yet to be demonstrated in soil. Expression of the atzA and atzD genes involved in atrazine dechlorination and s-triazine ring cleavage, respectively, was investigated during in situ degradation of atrazine in the soil drilosphere and bulked samples from two agricultural soils that differed in their ability to mineralize atrazine. Interestingly, expression of the atzA gene, although present in both soils, was not detected. Atrazine mineralization was greatest in Epoisses soil, where a larger pool of atzD mRNA was consistently measured 7 days after atrazine treatment, compared with Vezin soil (146 vs. 49 mRNA per 10 6 16S rRNA, respectively). Expression of the atzD gene varied along the degradation time course and was profoundly modified in soil bioturbated by earthworms. The atzD mRNA pool was the highest in the soil drilosphere (casts and burrow-linings) and it was significantly different in burrow-linings compared with bulk soil (e.g. 363 vs. 146 mRNA per 10 6 16S rRNA, 7 days after atrazine treatment in Epoisses soil). Thus, consistent differences in atrazine mineralization were demonstrated between the soil drilosphere and bulk soil. However, the impact of bioturbation on atrazine mineralization depended on soil type. Mineralization was enhanced in casts, compared with bulk soil, from Epoisses soil but in burrow-linings from Vezin soil. This study is the first to report the effects of soil bioturbation by earthworms on s-triazine ring cleavage and its spatial variability in soil. [ABSTRACT FROM AUTHOR]

We investigated the influence of earthworm ( Aporrectodea giardi) activity on soil properties and on atrazine (AT) adsorption and biodegradation by comparing a coarse-textured smectite-free wetland soil (Brittany, France) with the earthworm casts derived from the top horizon of this soil. Casts are characterized by lower pH, are enriched in organic carbon (OC) and clay content, have a larger cation exchange capacity, and a greater exchangeable Ca content. The clay mineralogy of the soil studied and casts is characterized by a muscovite–kaolinite–chlorite association. In addition, the clay fraction of the soil contains lepidocrocite (γ-FeOOH), which was not found in the casts. Atrazine adsorption isotherms were reasonably well described by the Freundlich equation and were all non-linear. The mean amounts of adsorbed AT for starting concentrations of 3–30 mg litre−1 ranged from 8 to 34%, being largest in earthworm casts. Soil AT adsorption capacity was well correlated with OC content. Non-decomposed organic matter present in the coarse size fractions and specific compounds present in earthworm casts (proteins, mono- and polysaccharides, polyphenols, sugars, lignin) and microbial and fungal biomass contribute to AT adsorption. Weak electrostatic (physical) sorption of AT on organic compounds and on mineral surfaces prevails. For casts, the formation of additional hydrophobic interactions between AT and SOM is proposed. We also studied AT biodegradation by the model bacterium Pseudomonas sp. strain ADP in the presence of soils or earthworm casts. An enhancement of the AT disappearance rate was observed in the presence of all the solid matrices tested compared with that obtained in an aqueous medium. The biodegradation rate was shown to be dependent not only on the OC content of the solid matrix, but mainly on its composition and structure. [ABSTRACT FROM AUTHOR]

The accuracy of eosinophil counts has been investigated. It is suggested that the assumption that such counts, performed under standard laboratory conditions, follow the Poisson frequency distribution is not a valid one since the sample variances consistently exceed the sample means. The negative binomial distribution has been fitted to the data and found to yield a convenient alternative frequency distribution. In Table 2, the accuracy of an estimate of an eosinophil count is given. It is suggested that this type of distribution may apply to the enumeration of other cells in the blood. [ABSTRACT FROM AUTHOR]

Details are recorded of the extraction and partial purification of an anti-coagulant obtained from mammalian liver. A pale yellow substance soluble in alcohol with 1/50 the activity (approx.) of heparin has been obtained. Partition chromatography yielded further concentration of the degree of activity. The active area in chromatography is fluorescent to ultra-violet light. The intravenous injection of 15 mg. into the rabbit reduces the coagulability of the blood for one hour with a high degree of significance. This publication describes orientation tests to indicate possibly effective and efficient avenues of purification. It is hoped that the study of this substance will be continued in the near future. [ABSTRACT FROM AUTHOR]