Our good friend Roseline is our first student presenter next week on February 12th. The title of her presentation is:
The Role of N2A and N2B Titin Isoforms in Muscle Cell Differentiation
She will be providing me a background paper to read, so check back to this post later.
Kory is scheduled to start the blog discussion following Roseline's presentation.
Roslyn's background reading can be found at the following URL:
Very good presentation! It is interesting to me how different expression patterns of titin isoforms can greatly influence the makeup of cardiac muscle at such early stages of cellular development. Reading more into Roseline's background paper, I noticed that the expression pattern of titin can vary greatly between muscle groups within a species, as well as between the same muscle groups across different species. I can understand the need for the different molecular makeups when comparing two different muscles, but I was surprised to see the difference in expression patterns of the same muscle in different species. What evolutionary pressures might have caused these specific muscles to require different ratios of titan isoforms even though the muscles are generally performing identical tasks?
ReplyDeleteYes, I agree, good job Roseline! Kory with regards to your question, I think that is interesting as well. It is interesting to think for example, like a muscle that flexes the forelimb, might technically be performing the same task. However, in different species that might not actually be the same thing. Like in a bipedal animal versus an animal that walks on four legs or climbs, the weight distribution etc could be different and that could play a role in pressures on the muscle cells to develop a certain way. Isn't that similar to Dr. Butcher's interest in the muscle of prehensile tails?
ReplyDeleteI agree with Jillian that it has to do with what the muscle is being used for. The muscles might be similar but have different uses depending on how they move such as climbing, swimming or running. I remember when Dr. Butcher talked in seminar about the opossums that use their tails to move in trees. They use their tails much differently than many other animals such as a horse which mostly uses it for keeping insects away.
DeleteOther reasons could exist as well relating to physiology and environment. For instance, certain isoforms may perform better at lower temperatures, which would be beneficial for animals living in cold climates. There could also be differences in the consumption of energy between isoforms, which would affect performance in oxygen-deficient conditions such as diving or burrowing.
ReplyDeleteI agree Marshall and protein isoforms in muscle could have differences depending on the how the animals moves. For instance, the different isoforms in cheetahs for quick bursts in muscle movement compared to a sloth that moves very slowly.
DeleteI agree Bill, as we evolve to different environments we must have different adaptations. Our muscles have had to evolve for many different climates and conditions. Throughout this evolution, different isoforms of titan could have arose.
DeleteI think one reason that could also explain the difference in ratios is specifically what each muscle is used for. Even when comparing different skeletal muscles in humans, there are muscles that will need to contract for much longer periods of time, as opposed to muscles that might only be needed for a short burst of force. For example, lower back muscles that help our posture will need to contract longer compared to your latissimus dorsi that you might only use to pull yourself up on a ledge. The lower back muscles may be more stiff, and therefore have a different ratio of titin isoforms, as explained in the background paper.
ReplyDeleteI agree with Marshall that it could have something to do with physiology and environment. The temperature idea is interesting, but I also wonder if there could be something that could be said for nutrient intake and that maybe it prefers one isoform over another depending on if food has been scarce or not.
ReplyDeleteI believe the different ratios of titin isoforms can be attributed to the size of the animal. In the background paper the larger animal (pig) had a higher N2BA count compared to smaller animals (mice and rats). A higher number of this isoform will lead to cells that are more compliant and flexible compared to cells that express a high amount of the N2B isoform. During diastole (blood filling stage) of the cardiac cycle, the more flexible monocytes will allow for a larger volume of blood to enter the ventricles which can be pumped over a greater surface area via systolic contraction. If it wasn’t for this differential splicing event, larger animals wouldn’t be able to successfully circulate their blood.
ReplyDeleteThis only pertains to cardiac muscle. For the titin isoforms in other kinds of muscle I believe that it depends on the muscle function; contraction/relaxation.
DeleteI wonder what effect the aging process has on the expression of Titin isoforms. The article didn't specify the age of the animals. If the animals are the same age it would be a controlled comparison, but if the different animals and different species of animal aren't of the same age the results may be confounded. It would be worth investigating the dynamics of Titin expression during the lifespan of the muscle.
ReplyDeleteThis is a very foreign topic about the different expression patterns of titin isoforms and how they can greatly influence the makeup of cardiac muscle. But I agree with Aaron in the fact that muscles do change with age and wonder how expression of Titin changes. I also would like to know what diseases have effected Titin expression.
ReplyDeleteI read the comments and agree with all of you. I also believe that, over time, our muscles have developed based on our current needs. I also agree with Aaron and Troy in wondering what the age of these animals were, I believe it plays a big role in determining the expression of titin and how it can change/vary. I will have to do more research to see if any of these experiments have been done. Also, Roseline did an excellent job in presenting! I am looking forward to doing my research with Dr. Walker on this topic
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