Crystallization And Preliminary X-Ray Analysis Of A Chitinase From The Fungal Pathogen Coccidioides Immitis

Chitinase is necessary for fungal growth and cell division and, therefore, is an ideal target for the design of inhibitors which may act as antifungal agents. A chitinase from the fungal pathogen Coccidioides immitis has been expressed as a fusion protein with gluathione-S-transferase (GST), which aids in purification. After cleavage from GST, chitinase was crystallized from 30% PEG 4000 in 0.1 M sodium acetate pH 4.6. The crystals have a tetragonal crystal lattice and belong to space group P4(1)2(1)2 or P4(3)2(1)2 and diffract to 2.2 Angstrom resolution. The unit-cell parameters are a = b = 91.2, c = 95.4 Angstrom; there is only one chitinase molecule in the asymmetric unit.National Institutes of Health GM 30048National Science Foundation MCB-9601096Foundation for ResearchWelch FoundationMolecular Bioscience

Modulation of functional connectivity following visual adaptation: homeostasis in V1

Abstract: Sensory neurons exhibit remarkable adaptability in acquiring new optimal selectivity to unfamiliar features when a new stimulus becomes prevalent in the environment. In conventionally prepared adult anesthetized cats, we used visual adaptation to change the preferred orientation selectivity in V1 neurons. Cortical circuits are dominated by complex and intricate connections between neurons. Cross-correlation of cellular spike-trains discloses the putative functional connection between two neurons. We sought to investigate changes in these links following a twelve minute uninterrupted application of a specific, usually non-preferred, orientation. We report that visual adaptation, mimicking training, modulates the magnitude of cross-correlograms suggesting that the strength of inter-neuronal relationships is modified. While individual cell-pairs exhibit changes in their response correlation strength, the average correlation of the recorded cell cluster remains unchanged. Hence, visual adaptation induces plastic changes that impact the connectivity between neurons