This week's seminar will be presented by Jordan Fain.
The title of her talk is “Comparative Analysis of Muscle Architecture and Myosin Heavy Chain Content in the Forelimbs of Geomyid and Heteromyid Burrowing Rodents” .
Her advisor is Dr. Michael Butcher.
Jordan gave an informative presentation on the differences in muscle fiber architecture and myosin heavy chain fiber typing between three burrowing rodents. It is interesting to see the different ways to measure the mechanical differences between the pocket mice, kangaroo rat, and pocket gopher. By examining the muscle fiber architecture, PCSA, and MHC fiber typing, force versus power of muscle types can be analyzed. Do you think that it is more beneficial for burrowing rodents to have more muscles that exhibit force or power? Do you think that larger burrowing rodents would exhibit similar findings as the smaller ones?
ReplyDeleteGreat job Jordan. Larger burrowing rodent's would have different MHC fiber types compared to smaller rodents. Smaller rodent's would have more power MHC due to being able to contact quickly than the larger rodent's. Larger rodent's are more forceful. To answer the first question, I think it would be more beneficial for rodent's to have power muscles due to power being work/time.
ReplyDeleteJordan’s presentation was enlightening. She also talked of the different isoforms of the myosin heavy chain (MHC) which when expressed within a muscle fiber represents variation in muscle power and force by the burrowing rodents. These are MHC-2X, MHC-2B fibers, MHC-2A fibers, and MHC-1 fibers. The muscle fibers that are highly oxidative and generate high power are important for rodents that burrow for it to be able to sustain its burrowing activities. Therefore, I believe rodents should have muscles with more power. I am not sure whether larger burrowing rodents would exhibit similar findings as the smaller ones but I think it would depend with the kind of activities they do.
ReplyDeleteJordan's presentation was informative as she touched on MHC (myosin heavy chain). Myosin is an important structure in muscle thick filament. Larger rogents, in my opinion, should have larger muscles as they need the muscles for greater work relative to smaller rodents.
ReplyDeleteIt was very helpful to hear about the muscles again after hearing about it from Dakota. It is amazing that such little critters can have such powerful muscles even though those muscles are so small. Humans think of great strength that you look like a body builder, but these critters so it is not always what you see on the outside that counts.
ReplyDeleteA wonderful presentation from Jordan. A muscle is capable of performing appreciable mechanical work at high power. The force and power that a whole muscle can apply are strongly influenced by the arrangement of the muscles fibers relative to the axis of force production within the muscle. By examining the muscle fiber architecture, it helps to determine how the extrinsic and intrinsic muscles are arranged and estimates the maximum isometric force and power. Physiological cross-sectional area (PCSA) is used to describe the contraction of pennate muscles. Pennate muscles with short fibers have larger PCSA thus ability to produce high isometric force which is required for sustained efforts required during burrowing. Burrowing requires not only the capability to exert forces large enough to disaggregate the soil, but also the capacity to receive the concomitant reaction forces without structural failure. Therefore, I think burrowing rodents need more muscles that exhibit force. Since smaller animals tend to have larger surface area to volume ratios compared to larger animals, I believe the findings will be different from the two rodents.
ReplyDeleteJordan gave an excelent explanation of her research! I would think that having muscles designed for high force output would be beneficial to burroughing animals in order to move dirt as they dig. However, with that said, I also think that whether or not an animal's muscles are force producing or power producing would depend on the animals lifestyle, foraging habits, and it's succeptibility to predation. If an animal does not have to worry as much about predators, then I think force would be the way to go as the animal doesn't necessarily have to move its limbs quickly to flee from anything, and I would expect this from larger animals. However, on the other end, if burroughing is a defensive mechanism from smaller animals at higher risk of predation, then having powerful muscles that are capable of producing large amounts of force in rapid bursts would be beneficial.
ReplyDeleteGreat job! Jordan gave a great presentation on her work with these 3 burrowing rodents. The question posed was about larger rodents. I believe that if the larger mammal were to have the same characteristics as these small ones ( i.e habitat, fossorial habits, food acquisition), then the larger mammal would essentially just scale up. The finding would be that the muscles still act in the same manner with no contribution to finite size. They would still need this forelimb musculature to move earth and burrow.
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