 Let us resume our 37th lecture. So, in the previous lecture we talked about the movement of the Mimosa pudic out the Tachminar plant. So, this is that is one kind of movement where you touch the plant and it leaves you know curl on you know bent and the whole leaf droops. Here we will be talking about a second kind of movement which is a very interesting movement where we talked about the carnivorous plants, plants which eats insects and plants which respond upon touching of the insects. So, essentially it is a same thing there has to be a pressure sensor or a touch sensor or something like that what is in Mimosa, but the mechanism is different from it, but the basic electrical activities are fairly the same. So, let us formally start this lecture with plant bioelectricity of the plant movement in the venous flight trap. So, this is basically what we are going to deal is the bioelectrical and bio mechanical phenomenon of carnivorous plant. The reason why I say bioelectrical and bio mechanical when we touch there is a mechanical even followed by a electrical even where this leads to a generation of a series of ionic current or fluxes of ionic currents followed by a mechanical action. So, the way it works for those who are not aware of it. So, there are series of plants which have very diverse geometries than you have ever seen. These plants have certain alluring feature most of the insects. So, we all know that you know the insects derive honey from the flowers and plants all over the place this is all we all of us know. So, these plants look really very beautiful and the insects gets attracted either by the color or the smell or whatsoever. When they sit on these plants they activate certain sensors and these plants are very unique their flowers are very unique say for example, you sit on it it has a flap which can which will close or it will have something which will you know curl back like this. So, there are series of geometries by which and it can trap the insects and today's lecture will be about that fascinating world of carnivorous plants and their movement where we talk about how they are trapping the insects and certain intriguing phenomena and certain unsolved mysteries of nature. So, talking about it. So, some of you may have seen some of these pictures some may not have seen. So, these are the examples just handful of examples of a series of carnivorous plants which are available in nature. There is a huge population of it there are 9 at least 9 families of plants with 600 species distributed all over the world and we really do not know how they evolved really. It is a very interesting story of evolution why they evolved how they evolved what made these plants. So, so very specialized as compared to other plants which just depends on water and other molecules you know to derive maximum part of their energy. So, if you look at the geometry of this plant in this slide from you know first second. So, the first one if you look at it there is a hood if you see the plant. So, there is a cup like elongated cup like structure and there is a hood second one if you see the same thing, but unlike a kind of you know it is much more you know more like you know ball shaped kind of if you see the third one. In the third one if you see extreme right third one you will see there as if there are lot of you know you have seen the propeller or the a of a helicopter it is almost like that. So, what happens from all the 4 sites or all the 5 sites or 6 what 1 2 3 4 5 6 all these 7 of them you know curve back like this. So, for example, they are all spread out like this. So, whenever they had to trap an insect they all will you know become vertical and will close on it. Similarly, if you see the fourth one very carefully. So, all those leaves which you are seeing spread out they all will you know curl back. Similarly, on the 1 2 3 4 5 6 and in between there is a small picture you will see where you will see some you know pointed between the 2 leaf flaps there are kind of these pointed structures as if there is spines spines like this you know. So, this is a different kind of structure. So, in this lecture we will be talking exclusively about this one family, but their mechanisms are same with barring aside few differences here and there. So, we will take one of these representative example and we will talk about their story. So, these are some of the among those 600 species either they will be pitfall traps of the pitcher plants or the leaves folded into deep slippery pools. So, that is what I was trying to tell you. So, if you look at these plants very carefully they really look very attractive there is every reason for an insect to get attracted towards them and not only that if you see the inner part of these plants inner part of these you know trap you will see it is kind of a slimy or slippery kind of situation. So, if you again focus on this picture out here the first picture it is very slippery and now if you follow this. So, the pitfall traps or the pitcher plants are leaves folded into deep slippery pools filled with digestive enzymes. So, they contain a series of enzymes which is the ability to you know digest and digest and small insect which plant does not produce unless otherwise it is needed you know plants depends on its own enzymes you know to break down the carbohydrates and likewise and so forth. But here these plant have a different kind of or added genetic machinery which allows it to produce series of digestive enzymes which could take care of these insect insect I mean you know degrade the insect. Then you have that the fly paper or the sticky or the adhesive traps of the sun dews. So, they have a sticky material which exude out causing sticky mucilage then you have the snap traps or steel traps of the venus fly trap what we are going to talking about water wheel plant and our hinged leaves. So, that is what I was trying to tell you they have the hinged leaves with those sharp spine structure then you have the suction trap unique to bladder warts are highly modified leaves in the shape of bladder with an hinged door lined with triggered hair. So, all of them have this hairy feature will be common then you have the lobster pot traps or the cork screw plant are twisted tubular channels lined with hair and glands. So, if you look very carefully through all these structures you will come across one common feature they all have these hairy appendages or a spiny structure which execute or which plays some significant role in this whole process of trapping the insect you know digesting it and extracting out the nutrients. So, now if you will see this picture in this slide. So, most of the time the insects kind of comes and sit getting kind of attracted about those mucilages and that is where it gets trapped. So, we will talk a little bit more now. So, this is the trap we are going to talk about the venus fly trap or the insectivorous plant the mechanism of movements and duration of the effects of the stimulation in the leaves of diagonal here. So, this is how they look like I told you that the small picture I was showing. So, look at the spiny structure of the leaves. So, they have two states either they will remain open as you could see one in one of the slide one of the leaves you see there is this red surface that is the inner surface. So, near the crease where the two leaves jaws. So, those are the jaws joints there is a series of tiny hairs you could see this hairy structure if an un-worry insect walk across these hairs touching two or more of them in succession this is very important the leaf will close quickly enough to prevent its escape unable to escape between the hair like teeth at the edges of the leaf the helpless insect is slowly digested and absorbed by the leaf glands of the leaf surfaces secrete several digestive enzymes that help to decompose the insects once the insect has been digested sufficiently the leaf reopens for another victim. So, now see this picture very very carefully you see the inner inner part of the leaf the two leaves the rather it is one leaf, but it is just kind of curling with the hinge out there which is red and the outer part which is green and then you see those doors hinge doors on the edges. Now, there is something very interesting from this picture you cannot figure out on those red surface I will be coming to that now look at it very carefully what you see on those red surfaces you see this pointed hinge coming out and they are very specific they are not very many numbers there if you see in the first panel under which underneath which is written figure 3 you will see 1 2 3 4 on one side and probably 1 2 3 is visible to me out here 1 2 3 4 4 on the other side and if you zoom on at each one of them it at least one of them this is in the figure 4 what you see as if there is a you know pin which is pointing out a spiny structure and this is how it looks like now these structures are very essential. So, what happens is this on these surfaces the insects get attracted either by the color or by the smell or by some slimy you know sticky fluid or something some fluid or whatsoever is present in between those that leaf like thing you know it looks like this. So, this the insect comes as if the insect comes out here imagine this pen as the insect. Now, you know one of the previous slide I was telling that insect has to remain there for a certain amount of time now these structures what you see 4 on one side now if you concentrate on the slide again there are 4. So, these are the sensor elements now if I go back I was telling you this sorry near the crease where the 2 leaves jaws join there is a series of tiny hairs if an unwoody insect walk across these hairs touching 2 or more of them in succession the leaf will close quickly enough to prevent it escape this line is important now what does that mean is these spiny structure what you see the 4 in one side 4 in other side the insect has to touch 2 of them in succession if it does not do then the leaf won't close as if 2 of them leads to a cascade of reaction now if you see it this is how it looks like when the when the insect touches 2 of them then leaf closes and it prevents its escape. So, this is very important that you understand this part. So, now see the sequence of events how this is taking place 0 second now this is this has been done without a insect how it has been done. So, these experiments could be done separately. So, how we discovered that it has to you know touch those 2 why from where this line is coming if an unwoody insect walks across these hairs touching 2 or more of them in succession the leaf will close quickly enough to prevent its escape. So, the way they figured it out is very interesting. So, now let us come back to this picture now you take a mechanical probe you see this picture you take a mechanical probe and you start touching those 4 on one side 4 on other side 1 after the other in succession 1, but there is a very tricky time delay and if I show you on the board it looks like this say for example, this is if this is the inner surface with those spiny structures coming out. So, I take a mechanical probe like this touch it followed by the second one this is the first touch then this is the second touch. This first and the second touch has to be done in such a way that there is very limited like if between touch 1 and touch 2 there is a huge gap of time then this phenomena would not be seen you understand this phenomena can only be seen if there is an optimal time between t 1 touch 1 followed by touch 2. If this does not happen that optimal time window then you would not be able to see this closure phenomena that is what it meant when the insect comes it has to touch this and this or this and this in succession with a very limited time delay. If that does not take place you would not be able to see this process now if you follow this with this picture on the board or now if you follow this picture on the slide that will make more sense. So, this is what you see out here there is a mechanical probe which is touching those 4 and 4 hair like structure 0 second 35 millisecond 67 millisecond likewise up to 64 seconds and in that whole process by inserting an electrode. So, the way it has been done these are the outer surface you insert electrodes like this and you can you know do the recording from an Eigen amplifier about how the electrical activities are taking place when you are touching. So, what you see essentially out here there is a electrode which is inserted here and there is a mechanical stimulus which is you know ensuring that you know you are disturbing this surface this is how it works you have to touch the mechanically these sensor elements and you have to do the mechanical electrical recording simultaneously. So, you touch it electrical recording you touch it. So, if you plot the graph like this it should be like this. So, this is for the mechanical stimulus. So, stimulus followed by an electrical signal stimulus followed by an electrical signal small delay out there this is how it works. So, this is exactly what this picture is trying to show you that 0 second 33 millisecond likewise up to 64 second and on 64 seconds you will see the leaf has closed and by trial and error of doing these things people had figured out how this venus flight trap works. Now, this is the kind of response properties of sensory hairs excised from the venus flight trap. So, those what you see are called the trigger hairs. So, this is these are those trigger hairs what I was showing in the board when these trigger hairs are triggered you see the closing motion of those along the hinge along the venus flight trap. Those trigger hairs are in a certain angle and over 100 millisecond time at angle changes likewise and you could see if you see the slide you will be able to figure that out much better. So, this is how that movement takes place. So, trap closure and trap closure memory trap closure is a precisely controlled process this is not a random process this is very very tightly controlled process as I was trying to tell you as I was showing you that you given a stimulus with a delay you will see electrical response. So, there is an optimal time window between these two and that optimal time window discovery is very was one of the very interesting feet for those people who are working in this area. So, coming back how these studies are being done first of all in order to understand it. So, the way these studies are being done something like this you see the slide picture and I will show you. So, if this is a venus flight trap situation with you know all those tiny structures coming these are those specific cells. Now, you remove it like this you remove a specific spine like this. Now, what do you do you insert an electrode out here then keep it in and you have a mechanical sensors which is hitting on it mechanical stimulator. This is your electrode now this is what I was trying to show you in the slide if you see the slide this is exactly what it is you have an electrode which is inserted through the center and you have the mechanical stimulator which is you know hitting upon it. So, whenever you are hitting upon it what you are doing you are measuring the electrical activity. So, if you read through this excise here preparation you see the excise sensory here was supported by an electron microscopic grid. So, the electron microscopic grid what you see out here in this picture is this you see this electron microscopic grid. So, this is the electron microscopic grid and if you follow this and was insulated to isolate the upper podium chamber from the lower chamber you want define the potential of an electrode in contact with the bathing solution with it. So, you are measuring with respect to the bathing solution and then you have this mechanical stimulator coming through. This is how most of this electrical activities of these kinds of sensory elements are being discovered over the period of time. So, now moving on to the slide next slide if you look at this structure very carefully this is the cross section and longitudinal section of the hair cells. So, these are called hair cells please do not mistake like you have hair cells in the ear also very similar to that though, but this are the hair cells of the plants, but the functionally they are same both of them are mechanosensitive structures one is in plant the other one is in the ear. Now, the cross section and longitudinal section of the hair cells the cross section at the left was selected from an indented level of a hair indented sensory cells from the outer margin. So, basically if you see this structure this is structure is something like this. So, they have on the periphery you have the sensory elements that is where your this kind of touch sensors are acting on the surface. So, these are those sensory cells what you see out here in that structure and if you follow the slide now the longitudinal section of the right the smaller cells occupy the central region of the tissue and the longitudinal section of the right includes only a fraction of the total liver tissue from the top and bottom the longitudinal section includes woody liver tissue the podium region. So, there are certain parts which are you know non-living part and they are existing out there. Now, from here if you look at it you can you know stimulate them at different typical results of destructive dissection you can really do a series of recordings based on how much stimulation or mechanical stimulation you are giving over a period of time. You guys can go through this is a very interesting thing, but what I will be more interested is to develop how people have developed this you know algorithm out there the electrical signaling in venous flight drive induced by a piece of gelatin. So, gelatin is acting as the stimulating one trigger at here at on each lobe. So, one ag agcl electrode was located in the mid-rip and the another ag agcl electrode is located in the center of the lobe. The channel 1 shows the solitary wave between the lobe and the mid-rip and the channel 2 show the electrical sky as spike in the lower part of the leaf. So, this is how these recordings. So, if you go back with this recording or even you know this is how it is pretty much the same assembly how these recordings are being done. Now, coming back what exactly is happening if you really look at it very carefully. So, this is the open trap. Now, follow it very carefully. Now, there is a prey. So, this is the open trap. Now, this is a prey which came here this is the prey it touch this one. So, this generates a receptor potential r p 1. Now, see the slide receptor potential the first mechanical stimulus followed by it puts it legs on this one and generates another receptor potential which we are calling as r p 2. This is exactly the same thing. Now, if you follow the slide this is exactly the same thing what happens when the light falls on your rodent cones or the sound wave hits upon the hair cells of the ear likewise. It is the same thing. So, there is a change in the receptor potentials followed by uncouplers or ion channels blocker they gets activated. And as soon as those ion channel blockers gets activated this leads to two different action potential. So, one action potential is coming from r p 1 the other one other action potential is generated from the other one where it is hitting. So, one action potential out here another action potential out here a p 2 and here you have a p 1. Now, there are two action potentials which are generated. Now, these two action potentials if you follow the slide now this leads to the electrical charge transaction and charge accumulation in the ATP and hydrolysis in the mid-drip. Now, followed by the next level. So, the part one if you follow this slide very carefully you see there are two dotted lines first one is the sensory activity part two is the electrical activity. Now, comes a part three part three is your mechanical activity. So, look through the trap closure in 0.3 seconds two holes in the mesh works allows the small prey to escape. So, there are situation when say for example, these two are folding and the insect is really agile and left what will happen how this algorithm will work. Coming back to the slide if you follow the left hand the holes in the mesh work allows the small prey to escape if that happens this system senses it and within one or two days it will open otherwise if the trap closes in 0.3 seconds and then the insect fails to you know escape from it then the prey is captured this is followed by now on these surfaces there are lot of digestive enzymes which are synthesizing enzymes which are present there. So, if this one closes now the trap becomes once it is first you have the sensory activity where your insect has touched on those you know hair cells followed by a change in the receptor potential one receptor potential two leading to an action potential AP one AP two and this whole thing is electrical activity. Now, followed by a mechanical action now this mechanical action is in the form of your this is the open situation and here is closed situation as soon as this one closes is a lot of secretion of from the surrounding cells out here lot of secretion of digestive enzymes the reason why this whole mechanism depends on two receptor potential changes or two action potential changes probably is nature is very conservative it does not allow the mistakes to take place. So, you know there may be a deflection or something by just by, but the insect may just ran away or you know something else. So, in order to ensure that there is an it must have must have been an adaptive process and the time difference between the two that is very critical from receptor potential one receptor potential two if there is this time window goes fairly high then this whole process is going to you know cancelled out is not going to take place. So, this is very important that this takes place very fast I mean there is a optimal time window without that optimal time window this cannot be executed this is very very very clear. Now, if we look at the different plant memories what we are having today in the world. So, electrical signaling in the memory play a fundamental role in plant responses. So, one of the thing is the most foremost one is the storage and recall function in the seedlings when the seed germinates this is a classic example of it has certain degree of memory it remembers it next is the chromatin remodeling the plant development. So, these are overall then you have the trans generation memory of a stress they could respond to the stress as if they have already memory recall switch by which they know how to respond then you have the fourth one as the immunological memory of tobacco plants and mountain birches. I wish or your students please go through them you know go through go to Google and you know give searches and you know see what all these significant because we are only talking about the electrical phenomenon, but they are different memory events which are taking place in plants. Now, then on the fifth one if you come on the slide vernalization and the epigenetic memory of winter winter hardness and cold hardness and all those things induce resistance the sixth one and susceptibility or to Harvey wores then you have the seventh one the memory response of abscessic acid entrained plants then you have the eighth one as the phototropically and gravitropically induced memory in maze and a ninth one ozone sensitivity of grapevine as a memory effect in the perennial crop of plants. Then the tenth one which we have talked about the memory of a stimulus this is exactly what we talked about this is called the memory of the stimulus we have talked about many of the eleventh one you see in the slide systematic acquired resistance in plants exposed to pathogen over a period of time you know they act on it then you have the electrical memory in the venus fly trap twelfth one what we have talked talked here. So, the way the electrodes are being so here I will be discussing with some of the mechanism how it is being done. So, you see the veins out there and you see the trigger hairs which are present there in the in the shadow ea now using charge injection method it was evident that application of an electrical stimulus. So, this is very interesting to note. So, as of now we talked about that there has to be a mechanical stimulus there has to be a mechanical stimulus before this whole process takes place. Now, it was being observed that whenever there is a change in the receptor potential out here what receptor potential change means that means those tissue are sitting at a resting membrane potential which is shown by RMP. Now, by some mechanical stimulus on them this there is a change in RMP resting membrane potential and that is what we are talking about resting potential change fine that is what if you remember sorry the receptor potential change now come back to this slide. Now, if I could the go on the third line open trap prey and the receptor potential. So, there is a mechanical stimulation leading to receptor potential change, but think of it without giving mechanical stimulus if electrically I induced a receptor potential change I change the potential electrically will this whole process be executed. Now, coming back to this slide just imagine if I this you see this line mechanical the first mechanical stimulation second mechanical stimulation what I was trying to show you you know the mechanical stimulation taking place here mechanical stimulation taking place here likewise in the R P 1 R P 2 you see the mechanical stimulation here mechanical stimulation here I do not give the mechanical stimulation what I did is I change the receptor potential by an electrical method will still this whole cascade of event coming back to the slides if you look at it will this whole cascade of event takes place and that is the experiment which was being done using charge injection method you can actually change the potential of the receptor potentials could be changed by charge injection using charge injection method it was evident that application of an electrical stimulus between the mid rip positive potential and the low negative potential causes when a slide trap to close without mark this line without any mechanical stimulus stimulation pulse voltage is sufficient for rapid closure of the when a slide trap was 1.5 volt this is very interesting to note that this process is in a natural condition this is this process is influenced by the mechanical response obtained by the plant because of insect sits on top of it but you actually can orchestrate the whole process of the closure without the mechanical stimulus just by inserting an electrode here inserting an electrode here and in a injecting current to change the receptor potential if you change the receptor potential this whole cascade of event will follow without doubt. So, what is the take home and the here in the slide if you come back to the slide you will see this is how these kind of you know charge injection methods are being followed being used precisely to estimate the amount of electrical energy necessary to cause the. So, what you are essentially doing so there is a mechanical energy here. So, now you are replacing the mechanical touch sensation with an electrical stimulus. So, when we are talking about the electrical stimulus essentially what you are telling is we are injecting a specific amount of charge particles. So, this is what the charge injection methods will highlight has been used precisely to estimate the amount of electrical energy necessary to cause the closing of the leaves. The two critical parameters have been analyzed the amount of charge and the applied voltage both parameters are tested to determine the minimum amount of charge and minimum voltage sufficient to close the plant trap the double pole double throw DP DP DT switch was used to connect the known capacity to a voltage source during charging and then to the plant during plant stimulation. So, this is how this whole thing is being is being carried out to quantify the charge and quantify the charging voltage and the this is how this whole thing is being followed. So, you see there are on off on off at the two levels. So, I wish you guys kind of go through them in a small large depending on how much charge you are giving the closure mechanism changes its slope. So, now if you see the slide open trap first stimulation second stimulation wait for mechanical stimulation by the prey change in the receptor potential the sensory memory action potential which is a short term memory followed by APT ATP hydrolysis which is basically a biochemical phenomena followed by a proton transport past H plus transport water transport through aquaporins which are the water channels fast trap closure. So, small prey if the holes in the c d m s allows the small prey to escape the trap reopens after two days, but if that is not the case and if you are the insect is completely trapped and with the effect of the digestive enzymes which are secreted by the leaf surface the cilia mass is locked looking at the slide if you realize then it would not open before four or five days. So, this is the overall the schematics which could be done and you can execute the whole process at the line two of the slide by electrical stimulation by giving it giving it charge. So, there are several models which are involved in this one of them is called in the slide you see hydro hydro elastic curvature model I wish you people to go through them basically it says that after receptor potential action potential has generated which are propagated to the mid-drip of the plant through the plasma dismatter. So, these are the connections if you remember in lecture 36 I showed you what the plasma dismatter lies on the connection which do with the lilamine flow emits and all those things. So, those plasma dismatter are very important. So, please go through the lecture 36 to see I gave I gave you in between an schematics of the plasma dismatter. Now, following in the slide action potential can be inhibited by uncouplers. So, you can use different kind of you know protection channel blockers and you can stop this action potential. So, you can actually stop this whole process here itself you may not allow this to proceed further. Now, coming back to the third the venous slider memorizes the first electrical signal for a short period of time and as soon as the second action potential propagates into the mid-drip in 1 to 40 seconds. So, this is the time window electrical signal. So, between this and this has to take place between 1 to 40 seconds this is that is the critical time window what I was telling you the T between T 1 and T 2 or some mechanical stimulation at 1 mechanical stimulation at 2. If there is 1 to 40 seconds delay and this process of ATP hydrolysis and everything is going to take place. If you see the slide that is the third box is going to tell you about that if you follow it the venous slide trap 1 to 40 seconds electrical signals activate the ATP hydrolysis starting fast proton transport initially. So, basically the whole proton transport when we are talking about out here this place becomes very very acidic because there is a huge amount of protons which are moving out there H plus ion concentration is really gearing up. The fast proton transport induces transport of water and change in the terger pressure. The leaves of the venous flight trap actively employs terger pressure and hydrodynamic flow for the fast movement and catching insect in these processes the upper and the lower surface of the leaf behaves quite differently. This is exactly the same situation as you saw in Mimosa Porica during the trap closure loss of terger by parenchyma lying beneath the upper epidermis accompanied by the active expansion of the tissue of the lower layers of parenchyma near the under epidermis closes the trap. The cells on the inner face of the trap jettison their cargoes of water shrink and allow the trap loop to fall over the cells of the lower epidermis expands rapidly folding the trap loop over. The minimum elastic energy of the leaf including mean and Gaussian curvature corresponds to the closest stick. So, this is what is the what I was telling about the hydroelastic curvature model. So, there are several other models which are involved in this whole process please go through them and so this is the overall what I wanted that there are mechanical events just like you know what happens in the nervous system there are mechanical event which are translated in your electrical event. And the mechanical event could be simulated by in using charges into those tissues and that is exactly what this experiment was all about. So, once again here this is the one which is all about where you are injecting the charges into it. So, overall if you look at it. So, by the action and reaction it looks very fairly similar that what is there in that animal system is pretty much followed by the plant world. But unlike the animal world plant do not have a very specialized nervous system well demarcated nervous system that is why back in 1926. So, JC Bose came with his idea that nervous system of plant are rudimentary or the probably the very kind of you know the most under developed nervous system before as animal king the animal evolved they developed much more you know higher organized structure. So, I will close in here and I will try to you know give few other hand out which may help you know appreciate this whole process. Thank you.