Toward a new theory of insect olfaction with Dr. Thomas M. Dykstra | Part 2 of 4
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- Опубликовано: 15 окт 2024
- AEA's Scientific Advisor Dr. Thomas Dykstra returns to share more insight into the world of entomology!
In this series of presentations, Dr. Dykstra will discuss the limitations of the current theory of insect olfaction and how species, such as aphids, perceive signals from plants.
Watch Part 1: • Here's the problem wit...
Watch Part 3: • Deciphering the Insect...
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(6:30) I have found many criticisms or contradictions of Dielectric Waveguide Theory/Vibrational Theory of Olfaction so this video is interesting to consider. I am curious to hear Dykstra's thoughts on these points since they weren't addressed in the last video nor this video. I notice also that much of the research referenced in the video is quite old, more than two or three decades in many cases. I study insect physiology professionally and have not come to the same conclusions so am curious to hear input about the following:
(3:19) Earlier in the video Dykstra mentions that insect odorant reaction time is faster than insect reaction to stimulus or diffusion through pores biophysically. He asserts that diffusion must happen in less than 12 milliseconds and references some research supporting this. Dykstra mentions also in the last video that a couple decades ago, the conclusions he came to don't make sense. It is possible that this is because there are no references to this newer research, or imprecise equipment at play which happens even to the best researchers for such a complex topic.
(15:00) Dykstra mentions a few important scientists investigating the Dielectric Waveguide Theory. As someone very interested in this aspect of insect physiology and whop has an advanced understanding of insect physiology, I'm surprised that the work of physicist Dr. Mark Diesendorf who published a commentary about the Dielectric Waveguide Theory of insect olfaction of Dr. Philip Callahan called, "Insect Sensilla as Dielectric Aerials for Scent Detection?" in 1976 wasn't mentioned.
Dr. Diesendorf describes the lack of evidence put forth by Dr. Callahan specifically regarding the hypothesized manner by which insect antennae detect infrared radiation from volatile compounds and several incompatibilities with how dielectric waveguides function. Also, that several researchers attempted to replicate previous experiments based on Callahans's approach and were not able to do so, and Callahan's omission of these experiments in the literature. The abstract reads:
"Callahan (1975) has espoused a mechanism of insect olfaction in which the antennal sensilla act as dielectric aerials (i.e. waveguides or resonators) in detecting characteristic wavelengths of infrared radiation emitted by excited, "free-floating" odorant molecules. However, no physically or biologically feasible mechanism has been put forward for overcoming the thermal black body background at infrared wavelengths. Antennal rubbing and antennal vibrations cannot play a role because the insect antenna is fixed during electrophysiology. Callahan's proposals for generating coherent emission of radiation are in conflict with basic physics."
On experimental results:
"To sum up, Callahan (1975) has provided no coherent, self-consistent description of a dielectric aerial method of scent detection which could be considered as a physically feasible mechanism. The onus is on Callahan to cite relevant experiments which support his position, especially since experiments have been performed which rule out the hypothetical mechanism for particular sensilla (Stange and Diesendorf, 1973) and particular insects (Hsiao, 1972). The different responses to enantiomers (optical isomers) observed in single cell and behavioural experiments (Kafka et al., 1973), also rule out a radiation mechanism in these cases. Moreover, although the recent interdisciplinary theoretical investigation of infrared radiation mechanisms of insect olfaction by Diesendorf et al. (1974) (the authors are, respectively, a theoretical physicist, a neurobiologist and an applied mathematician specializing in dielectric waveguide aerials) is listed amongst the references of Callahan (1975), not one of the severe limitations pointed out by them is explicitly acknowledged or discussed in Callahan (1975)."
(41:31) Dykstra references old research papers from 1987 and 1989, more than 30 years ago, that uses liposomes (which I agree are not comparable to studying the actual biology/electrophysiology) to test insect olfaction binding but I am surprised he didn't mention much more recent research that shows insect neural reactions to stimuli can be shorter than 2 milliseconds in several sampled insects, according to "High-speed odor transduction and pulse tracking by insect olfactory receptor neurons" in 2014 that do not rely on liposomes nor random proteins, but observed odorant binding to receptors in insect olfactory receptors. The researchers write:
"Here, we show that insect olfactory receptor neurons can have response latencies shorter than 2 ms and resolve odorant fluctuations at more than 100 Hz. This high temporal resolution could facilitate odor-background segregation, and it has important implications for underlying cellular processes (transduction), ecology (odor recognition), and technology (development of fast sensors)." In other words, more precise sensing equipment and techniques has allowed us to tell that reactions are not faster than diffusion speed of odorant-binding molecules.
Regarding diffusion time, the same researchers state:
"This short transduction time contradicts previous studies that suggested olfactory transduction times between 10 and 30 ms. What makes olfactory transduction fast? Olfactory transduction involves several steps, including diffusion of the odorant molecule through the antenna surface, its binding to an odorant-binding protein (OBP), diffusion through the aqueous sensillar lymph to an ORN dendrite, activation of an odor receptor, and opening of ion channels. Modeling studies suggest that diffusion can delay the initial ORN response by 10 ms. Using available data about OBPs and the sensillum lymph, we estimate that >17% of the odorant molecules should reach the ORN dendrite by 3D diffusion alone within 1 ms of encountering the lymph surface. Diffusion speed might be further increased by pore tubules that connect the sensillum pore with the ORN dendrite. Moreover, OBPs occur at high concentrations (10 mM) in the sensillum lymph of insects, which improves ORN sensitivity and might decrease transduction time." Several of the structures mentioned in the research have not been accounted for in this presentation, which may affect the conclusion.
"The structural basis of odorant recognition in insect olfactory receptors" was published in Nature in 2021, and depicted the physical binding of odorants with receptors, proving the receptor-odorant binding theory for insects, and there are some very illustrative graphs and diagrams. The researchers note:
"Notably, odorant binding relies predominantly on hydrophobic interactions, which lack the strict geometric constraints inherent to other intermolecular associations (such as hydrogen bonds) that frequently mediate ligand recognition. The distributed arrangement of hydrophobic and aromatic residues across multiple surfaces of the binding pocket further relaxes orientational constraints by allowing odorants to form comparable interactions with many of its faces." The interaction of volatile compounds with the binding pockets are special and allow for quicker detection.
(52:38) Dykstra mentions there is evidence for the electromagnetic theory of olfaction, and has looked at many spectra, but I would be very interested in seeing the data for resonant effects. The presentation is nice, but it doesn't contain any data that could be experimentally texted nor mention a lot of the more recent research that contradicts the vibrational/dielectric theory of olfaction.
Why don't I personally spend a single brain cell worrying about bugs, while most Cannabis growers spend all their energy, every bit of it, worrying about bugs or what to spray for bugs?
Why are you a bug expert, while, from my viewpoint, absolutely no one needs a bug expert?
Maybe it's the Bible vs Koran theory. Millions of people HAVE to be wrong. And they all read the same book, and are victims of the same agenda. You're reality comes from a narrative. You can't grasp an idea that's not prepackaged. It's not in you. Maybe that's why your type is being bred out of humanity via autism.
We'll just wait and see. I know you own stock in a pesticide company. There's no other reason to be a bug specialist when bug specialists are not needed. It's the same as a religious scholar. Expert on a created narrative designed for a reason. None of you book worshippers tell the truth, and couldn't in your lifetime if possible. You don't live in reality. I do, bug free. Pesticide free. You leave a trail of bugs and pesticides everywhere you go.
Well, in fact, both theory(and many theories) can be simultaneously correct. The reality is that it is likely no theory is actually true.
For example, suppose the standard model that the molecules bind to sites that effectively work at the chemical reaction level. Dykstra's theory is not at odds with such a theory. Why? Because both may be functioning simultaneously at some level or another. The antenna theory may be just a "side effect" or play some role that is misunderstood. Science should be less about trying to prove each other wrong so one can take home all the grant money. Science, itself, is never right and can't be. First, all models are models and not reality. Reality is infinitely complex and all models are finite.
For example, maybe as the molecules get closer to the antenna there is, due to the chemical nature, electrical field relationships that do create "antenna" like effects that may or may not be used by the insect but are still true due to the material nature of the design of the antenna(the fact that they are made out of stuff and all stuff has electric properties).
I have no idea about this science but it seems to me that the two theories are not necessarily incompatible and clearly his theory is true as an abstract, in the sense that it is based on established science. For example, you are an antenna... and when you eat food, even though you digest it, there are electrical effects that do exist and may or may not play some larger part.
Usually each person wants their theory to be true because, well, it makes most sense to them. In reality as long as the theories are based on evidence, science, and facts it is likely they will have *some truth* to them. That is, rarely is any theory completely wrong. So it's just a matter fleshing out the specifics and contractions to improve the theory in the right direction.
Not having any idea of insects and stumbling on this talk I find his arguments somewhat compelling from a physics and electrical perspective(I see nothing obviously inaccurate). Of course this doesn't mean he's right and surely he is myopic in some ways as everyone is.
@@jsmdnq I agree, the odor-binding theory of olfaction is well-supported, especially by research published recently in this century. It is surprising he states that odor-binding cannot be possible based on 30+year old research, and not more recent examples.
Without seeing Dykstra's data to replicate the models it is hard to do more than speculate or understand why that recent research isn't mentioned in the presentation. Speaking from personal experience, electrophysiology and insect physiological understanding has come a long way and like you say, no single theory is above scientific examination.
Enlightening is an understatement!
I have no prior knowledge about this material (soil microbiology student), but you are able to clearly explain the concepts to a novice Thomas. Looking forward to the 3rd one.
Ditto!
Oh man I was so excited to watch this! I've been waiting for this to come out, but then I had to wait until I could sit down and really pay attention to it. This is truly fascinating! As an extra class ham radio operator who likes to experiment with all different antennas, this opens up a whole new field of studies so to speak. If there are two things on this planet that I could hear about at the same time they're excite me it's farming and radio! Thank you so much Tom dykstra, thank you so much aea! Looking forward to part 3!
Yes! I've been waiting for this one! These are my absolute favorite!
Wow so much knowledge, explained, shared, contextualized. Appreciated.
Can you please make a webanar about nematode thx
We have now created a battery...come on Tom....
Here come all the bug boys from the weed farm.. Ever wonder why so many cannabis gurus are "experts" on insecticides and fungicides, almost exclusively? I haven't met one yet that can name 4 parts of a cannabis leaf.
I wouldn’t stereotype something like this. Remember John kempf and his families history?
name 4 parts of the human psyche
@@jeremyschissler337 ego, delta8, delta9, limonene
@@iwenive3390 keep kickin ass buddy ...much love
@@jeremyschissler337 conscious, unconscious, subconscious and the shared collective?
it is funny that these trolls are your biggest supporters 🤣🤣
Dykstra is one of the biggest sources of just BS claims in organic soil. Most of his claims in this video are from 30+ year old data which at this point in entomology is just horribly outdated. Zenthanol did a great breakdown of this.
Um zen uses 30+ year old data to make his claims…
@@iwenive3390 lol go back and reread the papers cited.
@@potentponics856 dude the papers range from the 50’s upward 😅
Everyone stands on the shoulders of giants
Is he going go address his false brix and insect detection claims at some point?
Why is it false?
This channel doesn't have any content lol
@@libranoelrose2207 impotent ponics
@@libranoelrose2207 he blocked my other channel for asking thr same basic questions. All thr white papers prove brix in no way makes your plants immune to insects as aphids, scales, whitefly, and leafhoppers can all feed at brix levels of 30+. He just ignores that for fanciful ideas. Same for his insect detection claims 30 years ago thr tech wasnt there to measure insect response times properly but modern results show less than 2 milisecond response times much faster than his claims. His work is based off of decades old papers that simply have no relevance with our modern understanding of insects.
@@potentponics856 you confuse ability with motivation. Just because something can doesn’t mean it prefers to.