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C Plant

Publications and source records attributed to C Plant.

23 records · Page 2Linked to original sources
PubMed1994

Two subcellular mechanisms underlie calcium-dependent facilitation of bioluminescence.

Epithelial calcium action potentials in Obelia geniculata trigger brief light flashes from specialized cells by direct activation of cytoplasmic calcium-activated photoprotein obelin. During a series of action potentials, sequential flashes undergo characteristic facilitation and decrement with no change in associated spike waveform. Analysis of the subcellular light distribution shows that facilitation results from two processes: recruitment of calcium entry sites and increased light from previously responding localized sites. We propose a model that accounts for the localized flash facilitation and decrement observed in vivo and is based upon the kinetics of calcium binding and emission of obelin. In this model, obelin emits light only when three calcium ions are bound. Changes in flash intensity during successive action potentials result from calcium bound persistently to unexpended obelin, effectively lowering the number of calcium ions required for subsequent activation. Accordingly, facilitation or decrement results from the time-dependent availability of singly and doubly bound obelin.

Action Potentials↗
PubMed1992

Molecular recognition of amiloride analogs: a molecular electrostatic potential analysis. 1. Pyrazine ring modifications.

Ab initio molecular electrostatic potential (MEP) patterns are used to determine the electrostatic requirements for the formation of a stable blocking complex between amiloride analogs and the epithelial sodium channel of Rana ridibunda. MEP maps calculated in the 3-21G(*) and STO-3G basis sets for amiloride and analogs with pyrazine ring modifications are used to interpret differences in the microscopic rate constants for analog-channel binding determined by Li et al. MEP maps of the protonated analogs are correlated to differences in the value of kon, the microscopic association constant. Those analogs with kon values similar to amiloride are found to have a MEP maximum that is localized over the side chain, as well as strong, distinguishing minima in the MEP pattern off the carbonyl oxygen and positions 3, 4, and 5 of the pyrazine ring. MEP maps of a model-encounter complex (protonated analog and formic acid anion) are correlated to differences in koff, the microscopic dissociation constant. The major conclusions of this work are that (1) a stable blocking complex is formed with analogs which have a deep, localized minimum off the 6 position of the pyrazine ring, (2) the stability of the blocking complex is directly related to the depth of that minimum, (3) substitution at position 5 affects not only the depth but also the location and size of the minimum off position 6, and (4) steric factors may influence the optimal binding of the 6-position ligand to the ion channel. The MEP analysis also suggests that the distance between the proton donors of the chelating guanidinium moiety and the deep, localized minimum off position 6 of the pyrazine ring may define an important spatial requirement for all those analogs which form a stable blocking complex with the channel.

Amiloride↗
PubMed1978

Field trials of brodifacoum (WBA 8119) against the house mouse (Mus musculus L.).

The anticoagulant rodenticide brodifacoum was tested against house mice (Mus musculus L.) infesting farm buildings. In six trials, treatment success was assessed from the results of census baitings conducted before and after treatment. With 0.005% brodifacoum in canary seed/corn oil bait, the control achieved ranged between 92.7% and 100%, mean 98.8%. Two mouse populations were eradicated in 3 to 4 weeks but a few individuals survived each of the other four treatments which lasted 6 weeks. The effectiveness of brodifacoum against mice is compared with that of 0.1% calciferol and 0.025% warfarin in combination. It is concluded that brodifacoum and calciferol warfarin are equally effective in controlling M. musculus but that brodifacoum treatments need to be conducted for a relatively longer period.

4-Hydroxycoumarins↗
PubMedDate not supplied

Identification of novel RPGR (retinitis pigmentosa GTPase regulator) mutations in a subset of X-linked retinitis pigmentosa families segregating with the RP3 locus.

The X-linked form of retinitis pigmentosa (XLRP) is a severe disease of the retina, characterised by night blindness and visual field constriction in a degenerative process, culminating with complete loss of sight within the third decade of life. Genetic mapping studies have identified two major loci for XLRP: RP3 (70%-75% of XLRP) and RP2 (20%-25% of XLRP). The RPGR (retinitis pigmentosa GTPase regulator) gene has been cloned within the RP3 genomic interval and it has been shown that 10%-20% of XLRP families have mutations in this gene. Here, we describe a single-strand conformational polymorphism-based mutation screening of RPGR in a pool of 29 XLRP families for which the disease segregates with the RP3 locus, in order to investigate the proportion of RP3 families with RPGR mutations and to relate the results to previous reports. Five different new mutations have been identified: two splice site mutations for exon 1 and three frameshift mutations in exons 7, 10 and 11. The percentage of RPGR mutations identified is 17% (5/29) in our genetically well-defined population. This figure is comparable to the percentage of RP2 gene mutations that we have detected in our entire XLRP patient pool (10%-15%). A correlation of RPGR mutations with phenotype in the families described in this study and the biochemical characterisation of reported mutations may provide insights into the function of the protein.

Base Sequence↗