Imaging synaptic inhibition in transgenic mice expressing the chloride indicator, Clomeleon

We describe here a molecular genetic approach for imaging synaptic inhibition. The thy-1 promoter was used to express high levels of Clomeleon, a ratiometric fluorescent indicator for chloride ions, in discrete populations of neurons in the brains of transgenic mice. Clomeleon was functional after chronic expression and provided non-invasive readouts of intracellular chloride concentration ([Cl(-)](i)) in brain slices, allowing us to quantify age-dependent declines in resting [Cl(-)](i) during neuronal development. Activation of hippocampal interneurons caused [Cl(-)](i) to rise transiently in individual postsynaptic pyramidal neurons. [Cl(-)](i) increased in direct proportion to the amount of inhibitory transmission, with peak changes as large as 4 mM. Integrating responses over populations of pyramidal neurons allowed sensitive detection of synaptic inhibition. Thus, Clomeleon imaging permits non-invasive, spatiotemporally resolved recordings of [Cl(-)](i) in a large variety of neurons, opening up new opportunities for imaging synaptic inhibition and other forms of chloride signaling.     

L value determination under paddy soil condition

Summary The L values of four paddy soils and one United Kingdom soil were determined under water-logged and aerobic conditions over a period of 7 weeks using rice and ryegrass as the respective test crops.Under water-logged conditions, the L values attained a constant level in the course of the growing period, indicating that isotopic equilibrium between the added P³² and the soil was achieved.Under aerobic conditions, the equilibrium L values tended to be lower than those determined under water-logged conditions.This was taken as an indication of an increase of labile soil phosphorus by reduction of ferric iron.     

Regulation of extracellular chitinases and proteases in the entomopathogen and acaricide Metarhizium anisopliae

Metarhizium anisopliae infects insects and ticks via a combination of specialized structures and cuticle degradation. Hydrolytic enzymes are accepted as key factors for the penetration step. The search for pathogenicity determinants has demonstrated that the process is multifactorial. Host specificity is an important factor to be addressed. The study of the enzymes produced during infection is important to discover those with a role in the process. To address some of the enzymes that take part during the infection of the tick, Boophilus microplus, we have analyzed the secretion of proteases and chitinases in single and combined carbon/nitrogen sources as compared with such complex substrates as chitin and B. microplus cuticles. Two chitinases, endo- and N-acetylglucosaminidases, and two proteases, subtilisin and trypsin-like proteases, were analyzed. Enzyme activities were detected in all carbon sources tested, but higher levels were found when combinations of carbon sources were used. A major 30-kDa protein apparently secreted during M. anisopliae growth on all carbon/nitrogen sources tested was demonstrated by SDS-PAGE.