Olfaction - Science topic

Antti, thanks for informing us about these new devices for detection of Covid-19. It would be very useful to know if there were particular VOCs that might serve as potential new biomarkers of this disease, within certain known chemical classes, that may have been identified among those volatile compounds detected by these particular devices. Thorough chemical and metabolomic analyses of the breath volatilome from healthy vs. Covid-19 infected patients could provide useful clues of the human metabolic pathways most affected by Covid-19 pathogenesis.

Malin Sandström Yes, it could. However, it is a kind of orthonasal flavor. Not really function to food and beverage, for which retronasal is more important.

Or of this:

Gilbert, A. N., Voss, M., & Kroll, J. J. (1997). Vividness of olfactory mental imagery: Correlations with sensory response and consumer behavior. Chemical Senses, 22, 686.

You may try to contact A. N. Gilbert or one of co-authors.

I agree with Japneet Kaur. The problem in the cilia of olfactory sensory neurons. The myofibrilar myopathy is a genetic disease that associated with the primary ciliary dyskinesia. The primary ciliary dyskinesia resulted in defective cilia and olfactory receptors.

Attached, please find the article describing both myofibrilar myopathy and primary ciliary dyskinesia.

Thank You Wender for you advise!

PLESE check it

Typically, it is considered that olfaction is initiated by the interaction of odoriferous molecules with olfactory sensory receptors in the olfactory epithelium. It is entirely valid only for the naïve animal that never been exposed to the odorant, and the odorant has no visual image or sound presentations. For example, if dogs are trained to the certain odorants accompanied with optical or acoustic signals, or have inherited the knowledge of the odorant (like an odor of fire) the process of olfaction involves other modalities like vision, hearing, memory, thinking, analyzing, etc. These additional odor information processing associated with training and learning can be investigated if the olfaction can be evoked not by odorant molecules, but acoustic, visual, or memory impression of the odorant. The vocalization of “baked potato”, “rose” or “wood fire” evokes the perception of odors of these objects in the human. The visual images of the same objects make one to smell the same things. There is evidence that some odorants can modulate emotion and cognition. The piriform cortex and the amygdala both project to the orbitofrontal cortex that with the amygdala is involved in emotion and associative learning, and to the entorhinal/hippocampal system that is involved in long-term memory including episodic memory. Although, the entorhinal cortex collects and distributes information about olfactory memory and serves as a top-down modulator of olfactory cortical function. The medial and orbital parts of the frontal cortex are involved in the cognitive integration of all sensory stimuli in relation to prior experiences.

The path from odorant to perception is quite complex. The initial events in olfaction take place in an olfactory neuroepithelium situated in the posterior nasal cavity. Olfaction begins with sniffing, that transports odorant molecules into the nose and delivers them to the mucus layer covering the olfactory epithelium. The binding of the odorant by a receptor protein initiates an intracellular cascade of signal transduction events, including the G-protein-dependent production of second messenger molecules, leading to opening of ion channels and passing of ion currents. This process triggers an action potential in the olfactory receptor neurons (ORNs) that projects directly to the olfactory bulb (OB). The signal is then transmitted to the anterior olfactory nucleus, piriform cortex, periamygdaloid cortex, and entorhinal cortex via olfactory stria. The signal at piriform cortex and periamygdaloid cortex is then sent to the thalamus and frontal cortex, where it is recognized and interpreted. The signal received at the entorhinal cortex projects to the hippocampus, where recognition memory of odors is processed. The anterior olfactory nucleus is involved in the processing of olfactory features and construction of representations (gestalts) for odorants. The correlations between olfactory gestalts are processed by the piriform cortex in association with frontal, entorhinal, and periamygdaloid areas. The periamygdaloid area is involved in processing the emotional information of the olfactory stimuli and memory encoding, whereas the entorhinal cortex collects and distributes information about olfactory memory and serves as a top-down modulator of olfactory cortical function. The medial and orbital parts of the frontal cortex are involved in cognitive integration of all sensory stimuli in relation to prior experiences. The thalamus’ role in olfaction is still controversial, whereas its involvement in odor thresholding and patterns of sniffing has been verified, at least in humans.

Back in the day, we would make our own small olfactometer systems. They have to be small for mites.  I would use polystyrene pill vials that can be cut by sawing with a metal-cutting (fine tooth) hacksaw blade, and glued together with superglue (to start) then sealed with 5 minute epoxy.  A sideways vibrating Dremel or Harbor Freight (cheap imported) vibrating saw ($14) with fine tooth blade will cut these vials nicely. Fine mesh of Stainless steel can be purchased from Grainger, or glue in plastic cloth mesh.  Nobody uses iron mesh anymore: Amazon and SIgma might not even have such an exotic material!

It sounds like you desire something rather basic and inexpensive like the strip chart recorder, but able to display the peaks on the screen of the PC. If that is your desire, then I would suggest looking at any of the available 16 or 20-bit Analog Input Boards (PCI-e Interface) in a one or two channel format with basic software. Most of the general electronic catalog houses and supply houses offer these for general purpose use with a wide array of instrument types (sensors, thermistors, thermocouples, voltage outputs...) and depending on your software needs and channel resolution, the pricing reflects the complexity desired. If you just want a simple way to display an incoming analog signal between -0.100 mV's and + 2.000 volts DC (normal output of a GC), then a basic card and software should do the trick. Just be sure to select one that is compatible with your computer (interface card type), your detector output and has a high quality analog to digital input converter with enough resolution (16 or better yet 20 bits) to display mV signals accurately.

BTW: Companies such as National Instruments sell instrument interfaces and software of this type, but they are VERY expensive and based on the information you have provided, I do not think you need anything like that.

*Additionally, you will need to figure out which of the two wires on your existing DB9 chart recorder connector provide the output signal you need (should be easy if your chart recorder already works this way).

Hi Thomas,

Please check the link for the gustometers.

Although it is not really within my scope of work, but I am not aware of any thorough recent review. There is rather a bit old generic pilot study from sussex suggesting possible positive influence on mental health, see below.

In the Netherlands, Jeroen Mos developed the "mostela", which is a combination of a tracking tunnel and a camera trap. They had good results with this, and the movies also made it possible to individually recognise the weasels based on demarcation line and cheek spots (which was not possible for ermines). Of course also lots of movies of the prey species.

Hi Sergey,

We got an answer form them that it should be fine to work with the olfactometer under the 160 ml/min range, but no more specifications. We will order new flowmeters and try to get it working, if still not then hopefully Toption can provide some help. Until then I was hoping to hear if anyone has been using successfully this instrument - maybe some publication with the exact system? 

Thanks for the reply :)

Rahel

Dear Andreas,

It is very important for the insect to quickly degrade the odorant particle (miliseconds, perhaps?) in order to avoid a signal repetition, enabling it to perceive changes of the compounds concentration in the environment. For that, there is a specific class of enzymes called Odorant Degrading Enzymes (ODE) that are responsible for destroying odor particles after they are released from ORs.

A very good review about that subject can be found on the link below:

Kind regards,

Pedro.

Dear Claudio (and Marcelo - both of you haven't changed at all, BTW!),

their facebook (https://www.facebook.com/kitepatch?fref=ts) and Indiegogo-page (https://www.indiegogo.com/projects/kite-patch#/updates) say that they performed what they call phase 1 in Uganda in April & May 2015. They are not going into what exactly they tested and how they did it, but it seems they also looked at possible attractive properties. Judging from their patent application (http://www.google.com/patents/WO2014028835A2?cl=en), these are probaly CO2-mimics.

I hope you are well, best wishes,

Andreas

Thank you Nilmini,

I am interested the most in metal nanoparticles.

Vitaly

Dominique- I am in private industry, am not allowed to publish, and so have no publications to view.  If I were in academia, it would be different, but this is the nature of the beast.  Our research is on insect olfaction.  We are looking at ORs, ORCOs and SNMPs all of whom, we reason, are involved in insect olfaction.  We are not interested in the genetic similarities as this has no bearing on our research.  Currently, we are interested in the physical properties of each of the three proteins.  You are welcome to email me, but I do not think I have much to offer someone with a background in immunology and antibodies.  Kindest regards, Tom

Dear Dr Depaulo,

Thank you for your answer and for the suggested references. It would be very useful to interact with Dr Sawa to exchange information and details.

I will defiantly give your regards to Maria.

 

Best regards,

Alessio

Thank you all for your response on my doubt. I shall contact them.

Nima,

The very low concentration of ETBE in PEX will require a sensitive method like SPME/GC to measure.  I am not aware of methods to reduce ETBE formation.

Regards, Professor Dietrich

Respiratory epithelium is actually quite complex in rodents; it contains several different cells types, which vary according to the level and depth of the nasal cavity. To study histologically, usually you fix the whole skull by formalin immersion, then lightly decalcify, then tranverse slices are taken rostral to caudal and embedded separately. You can then make sections of each slice and stain for histology, IHC, or even use for in situ (with the usual caveats that ISH on formalin-fixed tissue can be a bit more difficult than on frozen). If there are specific areas of the nasal epithelium that you want to target and isolate, then you would do LCM (laser-capture microdissection) to remove those areas from sections, then do your PCR analyses on the removed tissue.

please ,try the index R

I use it with my participants in aromatherapy and it helps.

Look for studies using the search term "physiological state" . That should help.

The end result of both pathways in OSNs is to open calcium channels, I'd be surprised if there was discrimination of enantiomers associated with either pathway. In addition, I've always understood that individual OSNs only have one type of messenger pathway. Therefore, if there is differential activation of secondary messenger pathways by enantiomers the activated pathway is not the source of the difference in reaction to the cue, but an indication of which class of OSNs reacts to the cue. 

Can the odorant specificity of an olfactory receptor be changed by associative training?

Odorants encountered in the environment help us find foods and avoid noxious substances. Successful food finding requires that perceived odors do no change from the first to the last encounter. The olfactory system is build under the guidance of genes, therefore mature olfactory receptor neurons (ORNs) in the olfactory epithelium are specialized olfactory neurons containing a single olfactory receptor protein. The specialized olfactory receptor protein binds the same odorants. Therefore the same olfactory receptor neurons (ORNs) during the repeated trials always carry the same information into the glomeruli of the olfactory bulb. The glomeruli are also specialized. In fish there are approximately a hundred different olfactory receptor proteins making a hundred specialized ORNs and a hundred different glomeruli in the olfactory bulb, in mammals the number of proteins and specialized cell types is closer to 1000 and approximately a 1000 types of olfactory glomeruli.

Specialized ORNs and specialized glomeruli enable that information entering the forebrain of fish or pyriform cortex of mammals is always the same. Olfactory percepts that are most probably formed there, in the third layer of the olfactory system must be stable during repeated conditioning sessions.  This is the condition sine qua non, which enables learning the conditioning stimulus, which enables that the same conditioning stimulus is always perceived as the same stimulus.

According to some investigators learning is located beyond the forebrain and according to other investigators in further layers of the pyriform cortex. Hypothalamus participates in learning the feeding stimuli.

Because it is possible to measure many parameters from the 2D tracks that are recorded with Syntech tracksphere there is not a single response.The first point to consider is what kind of data you will extract from the raw tracks.

You  might be more interested in directionality, final vector length and vector angle,  or mean angles that  require circular statitstics.  But in case you need to compare two treatments that appears to show some attractivity, other parameters that measure a response "intensity" may be calculated directly or with R scripts working from the csv files: total walked distance, speed, both can be treated by standard statistics.  And you can also make distribution stats on the numbers of animals that for instance walk a minimal distance or show positive attraction. 

I agree with Sven that 5 replicates is far from enough.  Due to variability in insect behaviour, 30 replicates per treatment are recommandable. You can find examples of application in our paper Party et al  2013 PlosOne (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0052897)

Dear Martin,

As far as my field of study is concerned, we only consider the PCs with eigen values greater than 1.

An odd number allows N-terminal extra cellular and C-terminal intracellular (usually) and 7 helices permit the possibility to form a pore of ideal size for ions and small molecules.

Dr. Downs - we observed this displacement of scent VOCs from soil by water and subsequent enhancement of analytical extractions (sample recoveries) from soil headspace. This 'flooding' effect is used to improve method detection limits for odorous VOCs from soil.

Wright, D., et al. 2005. Multidimensional GC-MS-olfactometry for identification and prioritization of malodors from confined animal feeding operations. Journal of Agricultural and Food Chemistry, (22), 8663-8672.

I do not understand. What is PET? polyethylene terephthalate?

I guess so, sample with those bags always contaminate plants. In case you do volatile sampling is best done in glass, no phthalates but to a lesser extent. I have a glass jar for potted plants adapted to volatile plant foliage is sampled only and is not sampled the soil. Do you want me to send a photo?

The main issue, as I see it, is conflating concentration of the odorant in the air with perceived intensity. One could easily have a chemical with a low concentration such as a mercaptan be rated as high intensity while vanillin at the same or at a higher concentration would be rated as very pleasant. The focus on matching concentration is misplaced. What you could do is have the subjects individually match the intensity of the pleasant and unpleasant odorant. I don't know if that would work in the context of your study. One should also consider the rate of adaptation as the study progresses. The unpleasant odor may not adapt at the same rate as the pleasant. It may not even adapt at all. More details of the study would be helpful.