| 1. |
- Majdi, Soodabeh, 1980, et al.
(författare)
-
Electrochemical Measurements of Optogenetically Stimulated Quantal Amine Release from Single Nerve Cell Varicosities in Drosophila Larvae
- 2015
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 54:46, s. 13609-13612
-
Tidskriftsartikel (refereegranskat)abstract
- The nerve terminals found in the body wall of Drosophila melanogaster larvae are readily accessible to experimental manipulation. We used the light-activated ion channel, channelrhodopsin-2, which is expressed by genetic manipulation in TypeII varicosities to study octopamine release in Drosophila. We report the development of a method to measure neurotransmitter release from exocytosis events at individual varicosities in the Drosophila larval system by amperometry. A microelectrode was placed in a region of the muscle containing a varicosity and held at a potential sufficient to oxidize octopamine and the terminal stimulated by blue light. Optical stimulation of TypeII boutons evokes exocytosis of octopamine, which is detected through oxidization at the electrode surface. We observe 22700 +/- 4200 molecules of octopamine released per vesicle. This system provides a genetically accessible platform to study the regulation of amine release at an intact synapse.
|
|
| 2. |
|
|
| 3. |
- Berglund, E Carina, et al.
(författare)
-
Oral administration of methylphenidate blocks the effect of cocaine on uptake at the Drosophila dopamine transporter.
- 2013
-
Ingår i: ACS chemical neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 4:4, s. 566-74
-
Tidskriftsartikel (refereegranskat)abstract
- Although our understanding of the actions of cocaine in the brain has improved, an effective drug treatment for cocaine addiction has yet to be found. Methylphenidate binds the dopamine transporter and increases extracellular dopamine levels in mammalian central nervous systems similar to cocaine, but it is thought to elicit fewer addictive and reinforcing effects owing to slower pharmacokinetics for different routes of administration between the drugs. This study utilizes the fruit fly model system to quantify the effects of oral methylphenidate on dopamine uptake during direct cocaine exposure to the fly CNS. The effect of methylphenidate on the dopamine transporter has been explored by measuring the uptake of exogenously applied dopamine. The data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter and the inhibition is concentration dependent. The peak height increased to 150% of control when cocaine was used to block the dopamine transporter for untreated flies but only to 110% for methylphenidate-treated flies. Thus, the dopamine transporter is mostly inhibited for the methylphenidate-fed flies before the addition of cocaine. The same is true for the rate of the clearance of dopamine measured by amperometry. For untreated flies the rate of clearance changes 40% when the dopamine transporter is inhibited with cocaine, and for treated flies the rate changes only 10%. The results were correlated to the in vivo concentration of methylphenidate determined by CE-MS. Our data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter for cocaine uptake, and the inhibition is concentration dependent.
|
|
| 4. |
- Grebner, Wiebke, 1985, et al.
(författare)
-
Induction of defensive traits in marine plankton—new copepodamide structures
- 2019
-
Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 64:2, s. 820-831
-
Tidskriftsartikel (refereegranskat)abstract
- Marine zooplankton release chemical cues, which trigger defenses in unicellular phytoplankton, such as increased toxin production and changes of colony sizes. Here, we identify the structure of two novel alarm cues belonging to the group of copepodamides. Similar to the known copepodamides, one of the compounds described is shown to trigger both amnesic and paralytic shellfish toxin production and chain length shortening in Skeletonema marinoi. In addition, we report the putative structures of another 21 copepodamides, which constitute 28% of the total copepodamides extractable from whole animals, suggesting that the copepodamide concentrations have been underestimated in earlier studies. We introduce a structure‐based nomenclature to handle the increasing number of copepodamides. Analysis of 12 copepod species showed that marine calanoid and freshwater cyclopoid copepods contain copepodamides. The only harpacticoid included in the analysis, Tigriopus californicus, did not appear to produce detectable amounts of copepodamides. Feeding experiments revealed that copepodamide compositions depend on both diet and species‐specific properties. Copepodamides induce both morphological and biochemical defensive traits in phytoplankton and may drive large‐scale trait–mediated effects in marine food webs. The more comprehensive list of copepodamides reported here makes it possible to explore the role of the copepodamide signaling system in the pelagic ecosystem in greater detail.
|
|
| 5. |
- Selander, Erik, 1973, et al.
(författare)
-
Copepods drive large-scale trait-mediated effects in marine plankton
- 2019
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Copyright © 2019 The Authors. Fear of predation may influence food webs more than actual predation. However, the mechanisms and magnitude of nonconsumptive predator effects are largely unknown in unicellular-dominated food webs such as marine plankton. We report a general mechanism of chemically induced predator effects in marine plankton. Copepods, the most abundant zooplankton in the oceans, imprint seawater with unique polar lipids—copepodamides—which trigger toxin production and bioluminescence in harmful dinoflagellates. We show that copepodamides also elicit defensive traits in other phytoplankton, inducing the harmful algal bloom-forming diatom Pseudo-nitzschia seriata to produce 10 times more toxins, and colony-forming diatoms to decrease colony size by half. A 1-year study in the northeast Atlantic revealed that natural copepodamide concentrations are high enough to induce harmful algal toxins and size reduction in dominant primary producers when copepods are abundant. We conclude that copepodamides will structure marine plankton toward smaller, more defended life forms on basin-wide scales.
|
|
