scholarly journals Light-induced reduction in excitation efficiency in the trp mutant of Drosophila.

1982 ◽  
Vol 79 (3) ◽  
pp. 361-385 ◽  
Author(s):  
B Minke
Keyword(s):  
Rise Time ◽  
Transient Receptor Potential ◽  
Light Adaptation ◽  
Receptor Potential ◽  
Background Light ◽  
Excitation Efficiency ◽  
Early Receptor Potential ◽  
Intensity Response ◽  
Trp Mutant ◽  
Transient Receptor

In the transient receptor potential (trp) mutant of Drosophila, the receptor potential appears almost normal in response to a flash but quickly decays to baseline during prolonged illumination. Photometric and early receptor potential measurements of the pigment suggest that the pigment is normal and that the decay of the trp response during illumination does not arise from a reduction in the available photopigment molecules. However, there is reduction in pigment concentration with age. Light adaptation cannot account for the decay of the trp response during illumination: in normal Drosophila a dim background light shortens the latency and rise time of the response and also shifts the intensity response function (V-log I curve) to higher levels of light intensity with relatively little reduction in the maximal amplitude (Vmax) of response. In the trp mutant, a dim background light or short, strong adapting light paradoxically lengthens the latency and rise time of the response and substantially reduces Vmax without a pronounced shift of the V-log I curve along the I axis. The effect of adapting light on the latency and V-log I curve seen in trp are associated with a reduction in effective stimulus intensity (reduction in excitation efficiency) rather than with light adaptation. Removing extracellular Ca+2 reduces light adaptation in normal Drosophila, as evidenced by the appearance of "square" responses to strong illumination. In the trp mutant, removing extracellular Ca+2 does not prevent the decay of the response during illumination.

scholarly journals Genetic dissection of light-induced Ca2+ influx into Drosophila photoreceptors.

1994 ◽  
Vol 104 (6) ◽  
pp. 1057-1077 ◽  
Author(s):  
A Peretz ◽  
C Sandler ◽  
K Kirschfeld ◽  
R C Hardie ◽  
B Minke
Keyword(s):  
Transient Receptor Potential ◽  
Large Fraction ◽  
Receptor Potential ◽  
Specific Protein ◽  
Genetic Dissection ◽  
Kinase C ◽  
Visual Mutants ◽  
Trp Mutant ◽  
Calcium Permeability ◽  
Transient Receptor

Invertebrate photoreceptors use the inositol-lipid signaling cascade for phototransduction. A useful approach to dissect this pathway and its regulation has been provided by the isolation of Drosophila visual mutants. We measured extracellular changes of Ca2+ [delta Ca2+]o in Drosophila retina using Ca(2+)-selective microelectrodes in both the transient receptor potential (trp) mutant, in which the calcium permeability of the light-sensitive channels is greatly diminished and in the inactivation-but-no-afterpotential C (inaC) mutant which lacks photoreceptor-specific protein kinase C (PKC). Illumination induced a decrease in extracellular [Ca2+] with kinetics and magnitude that changed with light intensity. Compared to wild-type, the light-induced decrease in [Ca2+]o (the Ca2+ signal) was diminished in trp but significantly enhanced in inaC. The enhanced Ca2+ signal was diminished in the double mutant inaC;trp indicating that the effect of the trp mutation overrides the enhancement observed in the absence of eye-PKC. We suggest that the decrease in [Ca2+]o reflects light-induced Ca2+ influx into the photoreceptors and that the trp mutation blocks a large fraction of this Ca2+ influx, while the absence of eye specific PKC leads to enhancement of light-induced Ca2+ influx. This suggestion was supported by Ca2+ measurements in isolated ommatidia loaded with the fluorescent Ca2+ indicator, Ca Green-5N, which indicated an approximately threefold larger light-induced increase in cellular Ca2+ in inaC relative to WT. Our observations are consistent with the hypothesis that TRP is a light activated Ca2+ channel and that the increased Ca2+ influx observed in the absence of PKC is mediated mainly via the TRP channel.

Inositol lipids and TRPC channel activation

2007 ◽  
Vol 74 ◽  
pp. 37-45 ◽  
Author(s):  
James W. Putney
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
Transient Receptor Potential ◽  
Calcium Signalling ◽  
Receptor Potential ◽  
Breakdown Product ◽  
Channel Activation ◽  
Inositol Lipids ◽  
Transient Receptor ◽  
Secondary Mechanism

The original hypothesis put forth by Bob Michell in his seminal 1975 review held that inositol lipid breakdown was involved in the activation of plasma membrane calcium channels or ‘gates’. Subsequently, it was demonstrated that while the interposition of inositol lipid breakdown upstream of calcium signalling was correct, it was predominantly the release of Ca2+ that was activated, through the formation of Ins(1,4,5)P3. Ca2+ entry across the plasma membrane involved a secondary mechanism signalled in an unknown manner by depletion of intracellular Ca2+ stores. In recent years, however, additional non-store-operated mechanisms for Ca2+ entry have emerged. In many instances, these pathways involve homologues of the Drosophila trp (transient receptor potential) gene. In mammalian systems there are seven members of the TRP superfamily, designated TRPC1–TRPC7, which appear to be reasonably close structural and functional homologues of Drosophila TRP. Although these channels can sometimes function as store-operated channels, in the majority of instances they function as channels more directly linked to phospholipase C activity. Three members of this family, TRPC3, 6 and 7, are activated by the phosphoinositide breakdown product, diacylglycerol. Two others, TRPC4 and 5, are also activated as a consequence of phospholipase C activity, although the precise substrate or product molecules involved are still unclear. Thus the TRPCs represent a family of ion channels that are directly activated by inositol lipid breakdown, confirming Bob Michell's original prediction 30 years ago.

Microbe Engineering of Guaia-6,10(14)-diene as a Building Block for the Semisynthetic Production of Plant-Derived (−)-Englerin A

2019 ◽  
Author(s):  
Thomas Siemon ◽  
Zhangqian Wang ◽  
Guangkai Bian ◽  
Tobias Seitz ◽  
Ziling Ye ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Synthetic Biology ◽  
Chemical Synthesis ◽  
Building Block ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Economical Method ◽  
Englerin A ◽  
Transient Receptor

Herein, we report the semisynthetic production of the potent transient receptor potential canonical (TRPC) channel agonist (−)-englerin A (EA), using guaia-6,10(14)-diene as the starting material. Guaia-6,10(14)-diene was systematically engineered in Escherichia coli and Saccharomyces cerevisiae using the CRISPR/Cas9 system and produced with high titers. This provided us the opportunity to execute a concise chemical synthesis of EA and the two related guaianes (−)-oxyphyllol and (+)-orientalol E. The potentially scalable approach combines the advantages of synthetic biology and chemical synthesis and provides an efficient and economical method for producing EA as well as its analogs.

Microbe Engineering of Guaia-6,10(14)-diene as a Building Block for the Semisynthetic Production of Plant-Derived (−)-Englerin A

2019 ◽  
Author(s):  
Thomas Siemon ◽  
Zhangqian Wang ◽  
Guangkai Bian ◽  
Tobias Seitz ◽  
Ziling Ye ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Synthetic Biology ◽  
Chemical Synthesis ◽  
Building Block ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Economical Method ◽  
Englerin A ◽  
Transient Receptor

Herein, we report the semisynthetic production of the potent transient receptor potential canonical (TRPC) channel agonist (−)-englerin A (EA), using guaia-6,10(14)-diene as the starting material. Guaia-6,10(14)-diene was systematically engineered in Escherichia coli and Saccharomyces cerevisiae using the CRISPR/Cas9 system and produced with high titers. This provided us the opportunity to execute a concise chemical synthesis of EA and the two related guaianes (−)-oxyphyllol and (+)-orientalol E. The potentially scalable approach combines the advantages of synthetic biology and chemical synthesis and provides an efficient and economical method for producing EA as well as its analogs.

Sign in / Sign up

Export Citation Format

Share Document