Lab Update II: Foot Prosthetics and Star Wars

As of right now, our lab’s main bread and butter is working with the muscle protein titin. Turns out this little protein’s role in muscle function has been overlooked for almost a century, and our lab is uncovering its role. In recent work, we have observed that titin has two identities: by day (relaxed muscle) the protein works as a passive elastic element that helps with the structural integrity of the muscle cells. By night (active muscle) it plays a much larger role in muscle properties (check the literature of the “winding filament hypothesis” or my earlier blog post for more).  

Anyhow, these properties can be understood in an equation (which we have one, thanks to collaborators), and this understanding can help us comprehend human locomotion better…and therefore has led us to start developing better prosthetics…foot prosthetics to be exact.

There are countless collaborators working on this foot prosthetic project all over the world…and there are a lot of moving pieces to the development process, but let me try to sum it up short. We are taking a foot prosthetic already in production (the Iwalk), and working with that company to make it better by adding our new understanding of muscle properties to the existing framework of the current prosthetic.

This prosthetic is used for trans-tibial amputees (below the knee leg loss). Thanks to an onboard computer, motors, accelerometers, and all these other great goodies, the prosthetic can make informed decisions about its environment and react the foot accordingly (like how the real foot works). The overall goal obviously is to make a Luke Skywalker-esque prosthetic (just not the hand). Our addition to the current prosthetic should help us get one step closer to this goal.

Progress: We are very early in the process, but making great progress. Many people are working very hard to get a working program into the prosthetic. We (that is a post doc Robert, an undergrad Eileen, an engineering grad student Jeremy, and I) are currently working on obtaining parametric data from non-amputee subjects. We are doing this by walking our subjects over a force plate while being filmed under high speeds. The force and video data is used in biomechanical analyses, which allow us to retrieve the parametric data necessary to help program/calibrate the prosthetic. Other groups are working on re-designing the motor aspect of the prosthetic (mechanical engineers) and building the program we hope to place into the newly designed prosthetic.

We have a long road ahead of us, but never fear: I will keep you posted on the developments.



Catching up with my salamanders


desmognathus ochrophaeus: Allegheny Mountain Dusky Salamander

desmognathus ochrophaeus: Allegheny Mountain Dusky Salamander

SoOoOo, it has been a long time since my last post, but never fear: I have spent the last 6 months hard at work. Over the next few posts, I will let you know what is going on in our lab. This post is all about salamanders jumping and me dorking out.

When we last left our hero, the salamanders had been jumped under high-speed camera and subjected to various biomechanic analysis. We learned that their jump somewhat mimics a fish’s “C-start” escape response, and could only be initiated when the salamander was under duress (my finger). The salamander bends its torso into a C-shape and then rapidly unbends its torso, pivoting on its inside foot and catapults itself into the air. Their take-off velocities could reach as high as 1.2 m/s, which converts to 2.5 mph-ish…which sounds slow, but consider that they average about 6-10 cm long (including tail) and we are looking at an animal that that moves 15+ times its body length a second! You would be hard pressed to find a 6 foot man able to cross 90 feet (30ish meters) in that span. Even Usain Bolt (my man!) can only tackle up to maybe 14 meters a second. Therefore: Go salamanders!

Where the magic happens. That is a phantom high speed camera and many LED lights
Where the magic happens. That is a phantom high speed camera and many LED lights


On further review of their kinematics, it is clear that their jump is somewhat sloppy. This makes sense since these little guys are not arboreal (tree-livers), and so never need to jump from place to place, expect to frantically escape death, therefore  natural selection would only favor just enough jumping ability to get away from their predators. (Though I would like to say a study on how they deal with falling through the air is underway!)

New Projects: My undergraduate researcher, Eileen Baker, and I are now focusing our efforts to understand where the energy for this jump comes from in the body. It is obvious that the quick bending and unbending of the torso plays a role in this…but what muscle supplies the power? Also, do the hips play a role in this launch? To make 2 months analysis short, yes, the hips play a pivotal role, by, well, pivoting around an inside planted foot (think of a catapult with the lever arm as the salamander leg and the rock being tossed as the body).

How much of a role does the hip play? We do not know yet.

How much of a role do the muscles play in the jump? We do not know.

Is there stored elastic energy in the muscles that accumulates during the bending phase of the jump and then expelled during the unbending phase (as is seen in human walking/running)? We do not know.

To answer these questions, we are going to jump our salamanders on a micro-force plate (thank you Dr. David Lee @UNLV for letting us borrow such a force plate), which after some nifty math work, should give us some answers to these questions.

Well that is the salamander saga, stay tune as new results pour in, and a lowly graduate student tries (and possibly fails) to make sense of it.


A Sampler of Future Posts: December and Spring Semester


The Nishikawa lab & Co. have been busy the last few weeks and we intend to keep on pushing right into the break. Kari, who is working on figuring out the change in the stiffness of active titin in mutant mice when compared to wild type mice (via a “shivering frequency” experiment) is almost done with her shivering data and her observations are raising some eyebrows. Kit (who is trying to understand how frogs can jump out of water) has just wrapped up frog jumping and after one more minor experiment, he will be ready to prepare a manuscript. Both of them are using this data in prep of their master thesis works. Once they have worked out the bugs, I will let you guys in on the results! A brief intro on their work can be found in earlier posts.

Our post-docs (Cinnamon and Jenna) both have their author hats on as they finish up their manuscripts (and experiments) on characterizing active-titin deficient mutant mice muscles on a force lever. I will try to write a post dedicated to their work in the next few weeks. Tentative results seem to support the Winding Filament Hypothesis on activated titin.

I finally started my salamander research! 2 weeks ago, I received 7 D.fuscus from Lisa Whitenack @ Allegheny College (they are adorable). As we speak I am finishing up characterizing their skin and passive muscle/element elastic properties to their C-start jumping mechanism. I will have some results to talk about next semester. In other news, I think that I have wrapped up a separate salamander project on tail loss effects. After I finish up the manuscript I will summarize it here. I should mention that I took on an undergraduate researcher, Megan Keenom. She is very capable and her work has allowed my work to run efficiently.

Next semester, we have a new PhD student coming in to begin work on incorporating our titin model into leg prostheses. We will be getting a new post doc to work on this project as well. Once I learn exactly how they intend to do this, I will be sure to pass it on into the blog.
Rene, who is our ex-lab tech will be continuing in the lab as a masters student!

The Nishikawa lab is going, in numbers, to the SICB national conference in San Francisco January 3-8th.

Check back for in-depth posts of everything above! Thanks for reading!


Conferences and Collaborations Part II

The Nishikawa lab was well represented at the 5th annual AzPS conference held at the U of A, Tuscon campus. Rene F, Kari T (Masters student), Jenna Monroy (post Doc), Cinnamon Pace (post Doc), Shane S (undergrad) and myself presented either talks or posters. It is great to travel as a lab once in a while, it allows the group to converse on topics other then science, which I feel brings the lab closer together. We brought out A-game as well. Shane won 1st prize for best undergrad poster, and Cinnamon won 3rd place for post-doc talks.

Some conference highlights was hearing about the work Kari is completing for her thesis, trying to link shiver frequencies in in mice with the “stiffness” of the muscle protein titin. Jennifer Vranish  (PhD candidate, UA) is doing some fantastic work on sleep apnea (snoring counts!). She is attempting to tone up the throat structures that usually “sag” while we sleep, limiting airway size (aka snoring or apnea). She is having subjects build this tone by having them suck on a straw (like one would when drinking a thick milkshake.) Early results on the control group are promising, and I am looking forward to hearing the results from the apnea group.

The Granzier lab (UA), also presented in numbers. They also work on the titin protein, but instead of skeletal muscle, they look at its function in cardiac muscle. I feel that we have a friendly competition with this lab group. We critically review each others posters and presentations, but in the end it makes both of our research work stronger, so I think it is healthy. I think that understanding other isoforms of titin are important because the change in function may shine some light on the purpose of titin in specific muscle types. The Granzier lab has some new grad students working with skeletal titin, perhaps our lab should consider working with cardiac titin as well.

The keynote lecturers were B. Walker (UNM) and P. Hoyer (UA). Both of these researchers have been working on their talk’s topic for over 20 years, and I found it awesome to listen to how the projects evolved over that time into what they became. Walker talked about “Novel mechanisms of vascular control in chronic hypoxia”, and Hoyer discussed “VCD (plastic byproduct) as a tool for understanding ovotoxicity and modeling menopause”. I suggest every person go to their lab websites and read up on this fascinating work.

In other news, I was elected (though unopposed) to the executive council of the society. I am hoping to keep NAU in the loop since we seem to be so far away from the action in Tuscon. I think that we should focus on getting our Exercise physiologists out to this conference. There work falls right into the scope of this conference.

thanks for reading!

A. Hessel

Conferences and collaborations (Part 1)

The past month started and ended with some great conferences.

The first weekend of October, I represented my lab at the Society for Integrative and comparative biology division of vertebrate morphology southwest regional meeting (SICB DVM SW). This was the founding meeting, so no one really knew how big it was going to be. So, when we all met at CS San Bernadino, I was not sure how it was going to run. Turns out, a lot of the movers and shakers in my field are stationed in labs in the Southwest United States, so the conference (with only 50 participants) was loaded with insightful talks and posters. A lot of “young” labs were able to come and showcase their new toys, in hopes of sparking collaborative efforts with others in the region. David Lee at UNLV showcased his new 3D X-ray set up that allows any animal to perform a movement while we view it’s bones system in real time. Very useful for biomechanic’s research.The Higham lab at UC Riverside presented some interesting work on the lizard’s mechanism for negotiating tight turns. The Azizi lab at UC Irvine is working on the toad’s landing mechanism (why does it not fall over when it lands?) They believe that the eccentric contraction of landing are strongly controls by the molecular muscle protein titin (which happens to be my labs main interest right now!) Ivo Ros (Biewener lab, Harvard) presented his dissertation work on figuring out how pigeons make tight turns (seems to use the same principals as a helicopter).  Another lab at UC Irvine presented an assortment of work on predator detection in fish when the predator attacks in a blind spot (the lateral lines plays a big role). Roy Heng at Cal Poly tech demonstrated how frogs frogs build up potential energy in their jaw pre-opening, so that when the mouths, the tongue can catapult out.

The keynote lecturer was David Carrier from the University of Utah. He presented some fascinating studies that looks at if human evolution was geared to be fighters (hands can make a fist, chimps cant, alignment of bones, ability to grapple due to bipedalism etc).

the conference was help in a small lecture hall, so the Q and A session was more of a forum discussion, then a direct question to the talker. I found this a really efficient way to give criticism to the study (and make it better! Or ask new questions). I encourage all my Southwest DVM counterparts to join me next year and join this conference’s critical mass of high quality labs/personals.

In Part II I will discuss the conference that I just got back from, the Arizona State Physiological Society (AzPS) meeting at the U of A, Tucson.

P.S.-I presented my past, present, and future directions on the salamander research.
I encourage all of you to Google these other labs and contact them if you are interested in the work. I can tell you that most of them love collaborating, or simply talking about there work with whoever is interested.


Lab Spotlight: Anthony Hessel (me)

Jack Be Nimble, Jack be Quick; Plethodontidae Jumps over the Candle Stick

Hey! Sorry for not posting in a few weeks. The start of the semester has been good, but busy. In this weeks installment of around the lab, I will let you get an over-the should view on what I will be doing for my thesis. I have some “side projects to (all very cool) that I will blog about later on in the semester.
My thesis has three components which look at the molecular, muscle and total body levels of a Plethodontidae (Lungless salamander) jump called a C-start.

Jumping Plethodontids have baffled researchers because their girdles and limbs remain highly underdeveloped for jumping. Their limbs almost always remain in a “pushup” position far away and perpendicular to their body while their ventral side rests in contact with the floor. In contrast, lizards and other higher vertebra that use their more highly developed and specialized hind limbs for jumping. Recent work observed the salamander jump originated in the torso rather than the limbs. This motion, called a C-start jump, mimics what one would see in startle responses observed in Teleosts (boney fish). The salamander, when stimulated by a predator will bend its body into a” C” and then rapidly straighten (unload) its body, propelling the salamander vertically and horizontally. Only the basic movements of the jump have been studies to date.

My studies hope to expand the knowledge of the C-start jump by studying multiple levels of the organism during the C-start.

During the unloading phase of the C-start, a large quantity of energy is expelled to allow the salamander to get off the ground. Where is this potential energy stored?  One idea would be that the muscle contractions of the axial (trunk) muscles themselves could unbend the salamander with enough speed to propel the salamander into the air. This is seen in the lateral bending of salamanders, lizards and fish. If contractions solely played a role in unloading, then the loading phase should have a similar angular velocity. Research shows that the loading velocity is much smaller than the unloading velocity. There may be a storage device at play during the loading phase that allows the storage of energy to be used during the unloading phase, and therefore would account for the extra velocity.

Elastic tissue acts like a rubber band or spring. If elastic elements are in use during the loading phase it is plausible that they are stretched during the loading phase and then released during the unloading phase passing on its stored energy for the jump.

There are a few kinds of elastic elements in vertebrate: passive (Collagen around the muscle cell and titin within the cell) and active (theorized second role of titin). Passive elements are always springy, while active elements work in unison of muscle contractions. I am curious if any or all of these element are at work in the jump. I have lined up three studies to help me answer this.

1) Under high speed, the salamander will be filmed performing the C-start jump. Following, the salamander will be anesthetized and then bent, by hand, into its C-shape and released. A high speed camera will watch the salamander straighten out. The two scenarios will be compared using kinematic analysis. The similarities and differences could help identify if the salamander is only using muscle contractions or elastic elements to gain its straightening speed.

2) EMG studies will be conducted on the salamanders to learn about the muscle control patterns of swimming, running and jumping in this family of salamanders. The knowledge from this will fill a gap in the literature on Plethodontidae and help us learn how these axial muscles work together to make this jump happen.

3) My work is under the premises that active titin exists, but to date it has not been proven. I am working at the molecular level to try and “prove” the leading hypothesis on the subject (Winding Filament Hypothesis) by running several TEM (transmission electron microscopy) studies, as well as RNA studies as well.
Alright, Now that I am sure you are all thoroughly exhausted from reading this long post, I will leave the molecular studies for a later date, but at least you know what I (and therefore the lab) am up too. Expect a weekly post once again, therefore, see you next week. We will discuss some pretty sweet TEM and SEM projects going on in the lab!

-A. Hessel

Lab Spotlight: Proving Titin as an Active Filement Part One: Rene and Jenna’s Study


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It is this lab’s theory that the large muscle protein titin binds actin and wraps around it to cause a stiffer “spring”. This spring, when pulled, caused recoil energy that we call elastic energy. There are two types of elastic filaments, passive (like collagen, cell structures) and active elastic filaments (we believe titin). We believe that Titin becomes receptive to binding after Calcium interaction at Titin’s N2A region. Once activated, titin is capable of binding to to actin filament and making that spring stiffer.

Theories are great and all, but here in the Nishikawa lab, our bread and butter is facts. Therefore, a slew of new studies are underway to prove our new theory. Some studies work on the molecular level (RNA work I am conducting…more in a few weeks), some are at the cellular level (Transmission Electron Microscopy studies by Kari, Kit, Shane (awesome undergrad) and myself), while others work at the whole muscle level (Rene, Jenna and Deidra).

Today we will look at the muscle level studies going on. Rene D. Fuqua, Jenna Monroy and Deidra Jensen are putting the calcium-binding-titin theory to the test. This is how their experiment plays out:From previous studies, we know that when muscle is stretched, a tension is create that is measurable. Compared to a non-active muscle, an active muscle that is stretched causes a higher tension…this is called force enhancement. Our lab believed that this force enhancement, or that added tension, comes from the activation of titin. SOOOO if we block titin from becoming active, or can show that something that is NOT part of the myosin- actin cross bridge is causing the force enhancement we can strengthen our lab’s titin theory.

The experiment design is like this: Rene compares active and inactive stretched muscles under different conditions to see if residual force enhancement is altered. One condition is blocking Calcium (which activates cross-bridges and titin in theory), blocking only cross bridge formation (not effecting titin in theory) and no blocking, which will have the normal process of the muscle. If she observes that cross-bridge inhibition still leads to a larger force enhancement then calcium-inhibition. We can assume that some other aspect of the muscle, besides the myosin/actin cross bridge, is causing the force enhancement. And in this lab, we believe that to be Titin, since it will not be effected by this inhibition, but will be affected by calcium inhibition, which is what this study hopes to show.

More information can be attained from Rene at




Nishikawa Lab Spot Light on Kari Taylor-Burt: Springs and Shivering Mice


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This week I got to catch up with Kari, a 2nd year grad student in the lab. Kari has worked on many projects in the lab to date including a TEM (transmission electron microscopy) project, where we are trying to visualize the protein titin (filament in muscle). She has also worked on jumping mice with muscular dystrophy with myositis (mdm). These mice have a deletion in the titin gene, and so have lost a valuable muscle component. By comparing jumping abilities of the mdm mice and healthy mice, we get to learn more about how this condition affects locomotion and more importantly how we can fix this in human via prosthesis applications.

For her thesis, Kari is working to further pinpoint titin’s role in muscles. Unfortunately, because of other elastic components, like collagen (connective tissue) and other cell filaments, it is difficult to pinpoint what are actually titin’s attributes compared to the other cellular components. To try and solve this, Kari is shivering mice. Why? because we think of active titin as a spring and therefore has a spring constant. Kari wants to find that spring constant. If she takes the shivering frequency of mice, and plug that into the spring equation with the mice weight, she can find the spring constant of titin.

The trick lies in sorting out titin from the other elements (as we just talked about). To do this, she is going to find the spring constants from healthy mice and mdm mice (missing titin). She will then subtract the mutant mice (missing titin) from the healthy mice (have all components) and be left with just the constant for titin itself.

Now there are a lot of other factors to consider, like the previously researched fact that there is more collagen in mutant mice then healthy mice. There has to be a way to naturalize that out if she wants her data to be meaningful. Other problems include the experiment themselves. The frequency of the shiver is recorded by tiny accelerometers that have been placed on the backs of mice. These guys are so sensitive that air-conditioning, cars outside, footsteps and a vibrating cell phone can all be picked up and so make it difficult to actually pinpoint the mouse shivering from all other ambient vibrations within the data. Kari is working hard right now to trouble shoot these problems, and hopes to have some solid data in within the next couple months.

If you would like to find out more about Kari’s work, you can contact her at

Fluid Dynamics, Frog water propulsion

Nishikawa Lab Spotlight: Kit Wilkinson


Kit has been working in the lab for a little over two years. His focus right now is on the world of fluid dynamics. More specifically he works with understanding how frogs are capable of jumping out of the water. In a nutshell, the frogs back feet, while pushing downward in the water, create a vortex that gives an opposite force on the frog feet, pushing the feet (and the rest of the body) out of the water. This vortex more specifically classified as a toroidal vortex.  (check out this video for what this class of vortex look like).

To prove these exist, or course, one needs to see every water particle moving, which is extraordinarily difficult to do. So, Kit, under his own designs, has created a way to “see” the water move in these vortex patterns using particle Imagery velocimetry. The work’s implications include prosthesis locomotion designs (biomemetic/bioinformatics) in the commercial world, and of course a new way to study all sorts of fluid dynamics (not just frogs jumping), thanks to kit’s new design. The physics and computer programing are well beyond my understanding, but I encourage you to check out his website for yourself and watch for published papers within the year.

You can contact Kit here:

Kit’s Website


Pilot post: Welcome!

Welcome one and all to my lab-bench blog. This blog will follow me throughout my academic career, as I move from lab to lab and meet many cool people. On this blog I will post what I am up to, including links to what other people are doing. Sometimes I will talk about my peer’s work extensively and sometimes they will do it themselves. I will give you the 411 on what is going on in the world of muscle physiology, bio-mechanic, animal locomotion as i learn about it myself. New knowledge that it presented at conferences will also be posted on here. I will also try to include the prep stages of research. This would include the little known world of grants, money, laboratory politics and publishing etiquette that exist in the research world that is all but lost when the work is discussed on CNN.

A little about myself:

Hey!!! I am Anthony Hessel. I am a first year grad student at Northern Arizona University  in Flagstaff AZ where I resided in the Nishikawa lab. I come from a small liberal art college in PA called Allegheny College. Originally I was not interested in the research side of science, and was set for a medical career. It was last second that I canceled my application to med school and switched to research instead. That turning point came during a summer research gig I had during the summer in the Whitenack lab, at Allegheny. Because there are no grad students there to do all the cool stuff, I was able to take control of the research being done, and so have been building on my craft for a little while longer then my peers.

The Nishikawa lab is great because it allows me to focus on my two main research passions: Muscle mechanics of locomotion, and molecular muscle physiology. Though these both compliment each other, it is difficult to cross these two specialties into one research environment. This lab blends them well, as it is now incorporating molecular approaches to their research of whole muscle kinematics.

I hope you enjoy traveling this Journeyman-ish path that is Grad school with me, and maybe learning something along the way.