Liming of wetlands in the Røynelandsvatn catchment — Effects on soil chemistry and neutralisation properties in the soil profile

In 1990, wetlands in the Røynelandsvatn catchment in Southern Norway were limed with finely ground limestone powder at a rate of 20 t ha^–1 to remediate acid discharge. JORDFORSK has investigated changes in the chemical properties of soil over a three year period in a selected limed fen. Calcium (Ca) contents above natural background levels were found in the uppermost 20 cm of the peatsoil. The major part of Ca introduced by liming was in the uppermost 3 cm of the peatsoil. Remaining Ca from liming is roughly estimated to be 2,5–3 t ha^–1. Similarly, pH of the uppermost cm of the peatsoil of the limed fen was around 7. Deeper peatsoils (> 20 cm) had pH-values around 3,8–4,9. After liming the dominance of hydrogen (H) — and aluminium (Al) ions in the exchangeable cation pool was replaced by Ca in the uppermost cm of the fensoil. In deeper peatlayers (> 20 cm) the exchangeable cations were still dominated by H⁺ and Al-ions. A smaller part of organically bound Al in the lime-influenced mire topsoil than in other peatsoil may indicate that Al has changed from an organically bound to a mineral (amorphous) phase. The liming has changed chemical properties of the uppermost part of the soil. This will counteract acidic and Al-rich input The results underline the origin of acid-neutralising effects and stress the importance of hydrology and patterns of water flow in the surface layers of mires.     

Amperometric determination of L-lactate based on entrapment of lactate oxidase on a transducer surface with a semi-permeable membrane using a SIRE technology based biosensor. Application: tomato paste and baby food

Determination of dissolved L-lactate in tomato paste and baby food samples using a SIRE-based (sensors based on injection of the recognition element) biosensor is reported. The measuring principle is based on the use of a small amount of enzyme, which is injected into an internal delivery flow system and held in direct spatial contact with the amperometric transducer by the use of a semipermeable membrane. Measurements are based upon the reversible enzymatic conversion of L-lactate to pyruvate and hydrogen peroxide by lactate oxidase. Differential measurements are performed in which the samples are measured in the presence and absence of enzyme allowing for control over matrix interferences present in crude samples. The linear range investigated for the determination of L-lactate in tomato paste and baby food was 0-0.1 mM using a lactate oxidase concentration of 22 U/mL. Samples were diluted with buffer prior to biosensor measurements. The L-lactate concentrations of the tomato paste and baby food were determined to be 1.02 +/- 0.02 mM and 2.51 +/- 0.10 mM, respectively, using the standard addition method. The repeatability for tomato paste and baby food measurements was 2.5% (RSD, n = 15) and 4.0% (RSD, n = 15) and the reproducibility was 13.0% (RSD, n = 45) and 3.0% (RSD, n = 45), respectively. The concentration of dissolved L-lactate can be used as a measure of freshness in the food industry. All biosensor measurements were compared with measurements from an established spectrophotometric assay (Boehringer Mannheim). It was found that the biosensor had good correlation with the spectrophotometric method. The biosensor gave 12% higher values for the tomato paste measurements and 2.5% higher values for the baby food measurements. However, a distinct advantage of the biosensor is that it can perform L-lactate measurements within 3 minutes, whereas the spectrophotometric assay requires a 35-minute measurement time.     

CRACM1 is a plasma membrane protein essential for store-operated Ca2+ entry

Store-operated Ca2+ entry is mediated by Ca2+ release-activated Ca2+ (CRAC) channels following Ca2+ release from intracellular stores. We performed a genome-wide RNA interference (RNAi) screen in Drosophila cells to identify proteins that inhibit store-operated Ca2+ influx. A secondary patch-clamp screen identified CRACM1 and CRACM2 (CRAC modulators 1 and 2) as modulators of Drosophila CRAC currents. We characterized the human ortholog of CRACM1, a plasma membrane-resident protein encoded by gene FLJ14466. Although overexpression of CRACM1 did not affect CRAC currents, RNAi-mediated knockdown disrupted its activation. CRACM1 could be the CRAC channel itself, a subunit of it, or a component of the CRAC signaling machinery.