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Biomedical subjects

J Gardner

Publications and source records attributed to J Gardner.

At least 415 records · Page 23Linked to original sources
PubMed1996

Calcium dependence of calcium extrusion and calcium uptake in mouse pancreatic acinar cells.

1. The droplet technique was used to investigate the calcium dependence of calcium extrusion from pancreatic acinar cells with preserved intracellular environments. The calcium dependence of calcium extrusion indicated a strong co-operativity (Hill coefficient, 3). The half-maximal rate of calcium extrusion occurred at an intracellular free calcium concentration ([Ca2+]i) of approximately 200 nM. At [Ca2+]i levels higher than 400 nM the calcium extrusion mechanism was almost completely saturated. 2. The rate of [Ca2+]i recovery was measured with the same cells under conditions where both calcium extrusion and calcium reuptake occurred simultaneously and under conditions when calcium reuptake was prevented and recovery depended entirely upon calcium extrusion. The rate of [Ca2+]i recovery due to calcium reuptake displayed a very sharp dependence on [Ca2+]i. The rate of [Ca2+]i recovery due to reuptake increased approximately 10 times (from 4.3 to 44.1 nM s-1) for an increase of [Ca2+]i of only 100 nM (from 120 to 220 nM). 3. With a decrease of [Ca2+]i the ratio of rate of calcium extrusion to rate of calcium uptake into internal stores increased, indicating that extrusion plays a more important role at low [Ca2+]i levels. Data for [Ca2+]i recovery rates due to extrusion and due to reuptake allowed us to evaluate the absolute rate of calcium translocation into the internal stores during the recovery process. When [Ca2+]i = 350 nM the total (i.e. bound and free) calcium concentration in the cytosol decreased by approximately 100 microM s-1 due to calcium uptake into internal stores. The rate of uptake was approximately 20 times slower when [Ca2+]i = 120 nM.

Animals↗
PubMed1995

A receptor kinase-like protein encoded by the rice disease resistance gene, Xa21.

The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic rice plants carrying the cloned Xa21 gene display high levels of resistance to the pathogen. The sequence of the predicted protein, which carries both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggests a role in cell surface recognition of a pathogen ligand and subsequent activation of an intracellular defense response. Characterization of Xa21 should facilitate understanding of plant disease resistance and lead to engineered resistance in rice.

Amino Acid Sequence↗