Improved nonporous magnetic supports for immobilized enzymes.

Ni powders coated by deposition of TiO2 or controlled oxidation to NiO develop substantial resistance to corrosion. Chymotrypsin immobilized to these coated Ni supports shows very high stability of activity on storage. Chymotrypsin immobilized by adsorption and glutaraldehyde crosslinking was fairly rapidly eluted under operational conditions in the presence of substrate. If 3-aminopropyltriethoxysilane (APS) was used to produce a covalent linkage, desorption of enzyme still occurred because of relatively unstable bonding of the silane to the oxide surface. A more stable attachment was produced by joining together many silane links with a layer of polyglutaraldehyde. The mechanism of action of APS as a coupling agent under these conditions is discussed. gamma-Fe2O3, and particularly a Mn-Zn ferrite, are suitable magnetic support materials available with smaller particle sizes. Particles below 1 mum give the expected higher specific activities of immobilized enzymes.     

Steroid synthesis in ovarian homogenates from immature mice treated with diethylstilboestrol in neonatal life

Female mice of the NMRI strain were treated with the synthetic oestrogen diethylstilboestrol (DES) for the first 5 days after birth. Pools of ovaries were removed from groups of 6-, 12-, 21-, 28- and 56-day-old females. An homogenate of an ovarian pool was incubated for 1 h in the presence of [3H]pregnenolone. Synthesized steroids were extracted and separated in a two-dimensional thin-layer chromatography system. Homogeneity of tentative steroids was verified with recrystallization to constant specific activity. Synthesis of [3H]progesterone and [3H]testosterone was demonstrated at 6 days, [3H]androstenedione at 12 days, [3H]17 alpha-hydroxyprogesterone at 21 days, and [3H]oestradiol-17 beta at 28 days. Up to 28 days (21 days for progesterone), the synthetic activity was lower in homogenates of DES-exposed ovaries than in control homogenates. After 28 days, values for recovered [3H]progesterone, [3H]androstenedione and [3H]oestradiol-17 beta were higher in DES homogenates than in control homogenates while the reverse was true for [3H]17 alpha-hydroxyprogesterone and [3H]testosterone. The results are compatible with an early and direct DES inhibitory effect on ovarian steroidogenesis and, later in immature life, a DES-induced disruption of the normal FSH-LH stimulation of ovarian development.     

Biocatalysis in multi-phase reaction mixtures containing organic liquids

A wide range of enzymes and whole microbial cells will act as catalysts in reaction mixtures that contain 2 or more phases, one of which is an organic liquid (either a reactant or including water-immiscible organic solvents). These "biphasic" systems have a variety of structures, knowledge of which aids predictions about biocatalyst activity and stability. There is often a dilute aqueous solution phase (containing the biocatalyst), which may be emulsified with the organic phase, or "trapped" within catalyst particles; sometimes however there may only be traces of water adsorbed to the enzyme or cells. These reaction systems offer several advantages for industrial applications, notably the higher solubilities of many reactants of interest, and the ability of readily available hydrolytic enzymes to catalyse syntheses. The most non-polar organic liquids are least likely to inactivate biocatalysts, though many do remain active with relatively polar solvents. Modification of the biocatalyst may stabilise against inactivation, especially where this is due to direct contact with the phase interface. The mass transfer processes required in these systems remain poorly understood, particularly because the interfacial area is often unknown. Attractive continuous reactors may be operated using a packed bed of catalyst with a trapped aqueous phase.     

Accuracy and precision of gait events derived from motion capture in horses during walk and trot

This study aimed to create an evidence base for detection of stance-phase timings from motion capture in horses. The objective was to compare the accuracy (bias) and precision (SD) for five published algorithms for the detection of hoof-on and hoof-off using force plates as the reference standard.     

P48-Triggered transmembrane signaling transduction of human monocytes:mobilization of calcium ion and activation of protein kinase C(PKC)

INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti…     

Carbon accumulation in agricultural soils after afforestation: a meta-analysis

Deforestation usually results in significant losses of soil organic carbon (SOC). The rate and factors determining the recovery of this C pool with afforestation are still poorly understood. This paper provides a review of the influence of afforestation on SOC stocks based on a meta-analysis of 33 recent publications (totaling 120 sites and 189 observations), with the aim of determining the factors responsible for the restoration of SOC following afforestation. Based on a mixed linear model, the meta-analysis indicates that the main factors that contribute to restoring SOC stocks after afforestation are: previous land use, tree species planted, soil clay content, preplanting disturbance and, to a lesser extent, climatic zone. Specifically, this meta-analysis (1) indicates that the positive impact of afforestation on SOC stocks is more pronounced in cropland soils than in pastures or natural grasslands; (2) suggests that broadleaf tree species have a greater capacity to accumulate SOC than coniferous species; (3) underscores that afforestation using pine species does not result in a net loss of the whole soil-profile carbon stocks compared with initial values (agricultural soil) when the surface organic layer is included in the accounting; (4) demonstrates that clay-rich soils (> 33%) have a greater capacity to accumulate SOC than soils with a lower clay content (< 33%); (5) indicates that minimizing preplanting disturbances may increase the rate at which SOC stocks are replenished; and (6) suggests that afforestation carried out in the boreal climate zone results in small SOC losses compared with other climate zones, probably because trees grow more slowly under these conditions, although this does not rule out gains over time after the conversion. This study also highlights the importance of the methodological approach used when developing the sampling design, especially the inclusion of the organic layer in the accounting.     

Rhodocybe pulchrisperma (Entolomataceae): A new species from North America

Rhodocybe pulchrisperma is described as a new species of Agaricales from North America. It belongs in section Rhodocybe due to the brightly colored pseudocystidia and lack of clamp connections. The very large, handsomely ornamented basidiospores distinguish this species from others in the section. A key to taxa from Florida, Papua New Guinea, and India that exhibit similar features is presented.