Effect of Chlorpyrifos-oxon and Piperonyl Butoxide on Acetylcholinesterase Activity in Monarch Butterflies
Abigail Berrios-Starbird
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07/28/2021
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Research on the inhibition of acetylcholinesterase and general esterases by chlorpyrifos-oxon and piperonyl butoxide in monarch butterflies.
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- [00:00:01.200]Hello. My name is Abigail Berrios-Starbird
- [00:00:03.930]and I did my research this summer on the effect of chlorpyrifos-oxon and
- [00:00:08.180]piperonyl butoxide on acetylcholinesterase activity in Monarch butterflies.
- [00:00:14.250]So to start off, chlorpyrifos-oxon or CPO is a type of organophosphate
- [00:00:19.140]pesticide.
- [00:00:20.520]These types of pesticides are able to inhibit acetylcholinesterase
- [00:00:24.450]which is an enzyme that breaks down the neurotransmitter acetylcholine.
- [00:00:29.790]If acetylcholine isn't being broken down because acetylcholinesterase is sufficiently
- [00:00:34.110]inhibited,
- [00:00:35.280]then there's a constant signal in the synapse and the insect will become
- [00:00:39.360]paralyzed and die.
- [00:00:41.490]Next, piperonyl butoxide, or PBO, is a
- [00:00:45.900]compound, which inhibits general esterase activity.
- [00:00:50.580]it's been shown that using this alongside other pesticide sites,
- [00:00:54.360]such as an another organophosphate or carbamate pesticide will enhance the
- [00:00:58.590]effect of that compound.
- [00:01:01.910]Looking into these sorts of relationships provides
- [00:01:03.760]better insight into the sensitivity or tolerance that important
- [00:01:07.440]pollinators such as Monarch butterflies may have for specific pesticide
- [00:01:11.670]treatments that may be being used.
- [00:01:14.070]The overall goals of my work for this summer were to look at how PBO
- [00:01:18.990]affects the general esterase activity in these monarchs.
- [00:01:23.550]Next it was to examine how CPO was affecting the acetylcholinesterase activity
- [00:01:28.470]in monarchs. Lastly,
- [00:01:30.300]it was to look at how the presence of PBO might affect the
- [00:01:34.980]overall acetylcholinesterase inhibition by CPO,
- [00:01:39.069]to see if that maybe enhances that effects like has been seen in previous
- [00:01:42.030]studies,
- [00:01:42.840]this was done using an assay that measures acetylcholinesterase activity and an
- [00:01:46.920]assay that measures general esterase activity.
- [00:01:50.760]These were in vitro assays performed using homogenate collected from
- [00:01:55.620]Monarch caterpillars.
- [00:01:57.030]So first off I looked at how esterase activity was affected using different
- [00:02:01.950]concentrations of PBO. And you can see here,
- [00:02:06.240]there is decreased esterase activity at higher PBO concentrations.
- [00:02:10.620]So that just shows that PBO is inhibiting esterase activity in these
- [00:02:15.390]Monarch caterpillars.
- [00:02:16.880]So next I looked at how
- [00:02:18.580]CPO was effecting acetylcholinesterase activity.
- [00:02:21.880]And as you can see, you get decreased
- [00:02:25.563]acetylcholinesterase activity with high concentrations of CPO,
- [00:02:29.353]which is as expected
- [00:02:31.456]You can also see that, for the homogenate that was treated with PBO,
- [00:02:35.236]there's actually decreased acetylcholinesterase activity
- [00:02:38.606]for these higher concentrations of CPO that's on the right there.
- [00:02:42.820]So first of all,
- [00:02:43.900]what this data shows us is that a acetylcholinesterase activity can be
- [00:02:48.820]significantly inhibited by CPO in these Monarch Caterpillar's.
- [00:02:52.840]This is expected since CPO is a pesticide.
- [00:02:55.630]So it's working as intended in this case. Additionally,
- [00:02:59.140]what was found that was that PBO inhibited general esterase activity,
- [00:03:03.640]but not acetylesterase.
- [00:03:05.220]At the same time, by treating the homogenate with the PBO,
- [00:03:08.840]the effect of the CPO was actually enhanced and acetylcholinesterase
- [00:03:12.850]was further inhibited than just with the CPO on its own. So that suggests.
- [00:03:17.700]That one or more of the esterases that PBO is inhibiting has the ability to
- [00:03:21.630]sequester insecticides such as CPO and reduce their toxic action.
- [00:03:27.120]So for future works in this area,
- [00:03:28.829]it would be important to look at other similar compounds,
- [00:03:31.490]such as organophosphates or carbamates that work in a similar way to inhibit
- [00:03:37.010]acetylcholinesterase and look at how tolerant monarchs are of those
- [00:03:41.790]substances. Additionally,
- [00:03:43.910]you would want to look further into this possible insecticide sequestration in
- [00:03:48.420]these esterases
- [00:03:49.920]to better confirm that that's actually what's happening in these monarchs.
- [00:03:54.700]This work that I've done was funded by a grant provided by the USDA National
- [00:03:59.440]Institute of Food and Agriculture.
- [00:04:02.260]Thank you for listening to my presentation and have a nice day.
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