muscle

Growing meaty fish

dr. dolittle — Mon, 27 Feb 2017 22:26:17 +0000

Growing meaty fish

Image of a gilthead sea bream by Roberto Pillon - via Wikimedia Commons

Similar to humans, muscle growth in fish is increased with exercise. Unlike humans, however, teleost fish are able to continue growing in length as well as weight throughout their lives. This type of meat, I mean muscle, growth happens in two ways: 1) muscle cells get bigger and 2) new muscle cells form. Researchers at the University of Barcelona in Spain wanted to know what effect moderate sustained swimming would have on the muscles of young fingerling gilthead sea bream, a type of teleost fish (image above). Their findings were published in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.

The fish were placed in either a tank with normal water flow (350 liters per hour) for voluntary movements or moderate flow sufficient for the fish to swim at a moderate intensity (700 liters per hour). After 5 weeks, they found that muscles towards the head of the fish began to remodel and grow new blood vessels to supply the new muscle cells that were also being produced. These anterior muscles are known for producing powerful and fast contractions and their study shows that they can indeed be changed by swimming during a time when the fish are normally rapidly growing anyway. In contrast to the anterior muscles, those closer to the tail of the fish showed closer to normal growth patterns. Since these fish are important in aquaculture, being able to optimize their growth and the quality of their meat is important.

Source:

EJ Vélez, S Azizi, E Lutfi, E Capilla, A Moya, I Navarro, J Fernández-Borràs, J Blasco, J Gutiérrez. Moderate and sustained exercise modulates muscle proteolytic and myogenic markers in gilthead sea bream (Sparus aurata). American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. [In Press] doi:10.1152/ajpregu.00308.2016

dr. dolittle Mon, 02/27/2017 - 17:26

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Life Science

aquaculture

fish

growth

meat

muscle

swimming

I think that growth patterns and locations of muscle on the fish is very interesting! Because this experiment was perfumed under moderate condition, I wonder what the result would be if the flow of water was higher than normal. Would the location of muscles growing in the fish change? Here is another article that talks about how the muscles of a fish for together to move it forward. http://jeb.biologists.org/content/202/23/3397

Muscle Aging in American Quarter Horses

dr. dolittle — Tue, 28 Jun 2016 22:20:13 +0000

Muscle Aging in American Quarter Horses

Skeletal muscle function and structure change as we age. Humans typically experience a loss of muscle mass or muscle weakness which can greatly reduce mobility and stability. While much is known about aging skeletal muscle in humans and rodents, less is known about horses, which are rather athletic animals that are living longer due to advancements in veterinary care and retirement programs. Researchers from the University of Florida decided to explore how aging effects skeletal muscles of horses. To do this, they examined gluteus medius (speed and locomotion) and triceps brachii (mainly postural) muscles in sedentary Quarter Horses aged 2 years old (young) or 17-25 years old (i.e. aged). Their results were recently published in the Journal of Applied Physiology.

The team characterized the fiber type of each muscle as well as the number and function of mitochondria. With aging in humans and rodents, there is a decline in the function and/or number of these energy producing organelles. This video is a nice review of the muscle fiber types and role of mitochondria:

Examining muscle biopsies, the research team found that the number of mitochondria were decreased in the triceps, but not gluteal muscles with aging. They also found changes in the muscle fiber type with aging. A high proportion of type II fibers (like in gluteus muscle) gives horses their speed whereas more type I fibers play a role in maintaining posture (like in triceps). With aging, the gluteus muscle develops more type I fibers and the triceps muscle develops more type IIA fibers with less IIX fiber types in both muscles. Although the activities of some mitochondrial enzymes also declined with aging, it was not associated with a decline in mitochondrial function. The authors attributed this lack of measurable mitochondrial dysfunction to either the horses not being old enough for dysfunction to exist yet (20 years horse = about 65 years human) or perhaps that aging in horse skeletal muscle is different from that of rodents and humans. Either way, understanding how our equine friends age is fascinating.

Source:

Li C, White SH, Warren LK, Wohlgemuth SE. Effects of aging on mitochondrial function in skeletal muscle of Quarter Horses. Journal of Applied Physiology. Article in press June 9, 2016. doi: 10.1152/japplphysiol.01077.2015

dr. dolittle Tue, 06/28/2016 - 18:20

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What about the role of the Hox genes, are there conserved between the species? It would be interesting to know if horses had them too, since we know they have an influence on muscle aging. We shortly discussed it in a article on Long Long Life : http://longlonglife.org

Heat stress in livestock

dr. dolittle — Thu, 31 Mar 2016 11:27:15 +0000

Heat stress in livestock

Photo by: Myrabella / Wikimedia Commons, via Wikimedia Commons

With the approach of summer, a timely study was published in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology on whether inflammation plays a role in heat stress-related complications in muscles. Heat stress is a major problem in the livestock industry. In the United States alone it is reportedly associated with a loss of approximately $158 billion annually in the swine industry. To cool off, swine seek shade and often mud baths (which mimic sweating by helping the animals cool off through evaporation). Despite well-known complications associated with heat stress, like stroke, the effects in skeletal muscle are less understood. The research team exposed swine to either 75.2 degrees F (24degC) or 98.6 degrees F (37degC) for 12 hours. What they found was increased inflammation in skeletal muscles from heat-stressed animals.

Thus strategies to help keep animals and humans cool are clearly important in hot weather.

References
S Ganesan, C Reynolds, K Hollinger, SC Pearce, NK Gabler, LH Baumgard, RP Rhoads, JT Selsby. Twelve hours of heat stress induces inflammatory signaling in porcine skeletal muscle. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. [Epub ahead of print]. DOI: 10.1152/ajpregu.00494.2015

http://www.livescience.com/32118-do-pigs-sweat.html

dr. dolittle Thu, 03/31/2016 - 07:27

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2013 August Krogh lecture on comparative physiology

dr. dolittle — Mon, 25 May 2015 16:54:32 +0000

2013 August Krogh lecture on comparative physiology

Dr. Stan Lindstedt, Northern Arizona University Recipient of the 2013 August Krogh lectureship, American Physiological Society, Comparative and Evolutionary Physiology section

I am thrilled to see Dr. Stan Lindstedt's review article published in the April 2015 issue of American Journal of Physiology: Regulatory, Integrative and Comparative Physiology from his 2013 August Krogh lectureship at the annual Experimental Biology conference. My original blog from the lecture can be found here.

Dr. Lindstedt and co-author Dr. Niisa Nishikawa (Northern Arizona University), describe the importance of comparative physiology especially in an age of molecular discoveries. Not only does comparative physiology examine unique adaptations such as the ability for animals living in desert environments to form highly concentrated urine thereby preventing water loss, or the ability of bar-headed geese to fly over Mount Everest, but emphasizes that patterns may emerge when comparing multiple species that are often hidden if only examining one. This concept of "Unity in Diversity" was introduced in the review as one of the reasons why comparative physiology remains such an important and powerful field. An example given for this is body size. Animals of varying body sizes still possess the same types of cells and biochemical pathways, but this variable alone is fundamental in the regulation of physiological processes. Thanks to some experiments involving LSD and quite a lot of research since then (see article for specifics), we know that an animal's metabolism is negatively correlated with body mass such that the metabolism of a small animal is greater than a large animal (think elephant vs. mouse). The use of comparative physiology is thus described as a major tool in developing novel hypotheses by studying patterns that may emerge through species comparisons.

Source:

Lindstedt SL, Nishikawa KC. From Tusko to Titin: The role for comparative physiology in an era of molecular discovery. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. In press. doi:10.1152/ajpregu.00405.2014

dr. dolittle Mon, 05/25/2015 - 12:54

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Life Science

comparative physiology

muscle

Northern Arizona University

Stan Lindstedt

unity

Wednesday: Grand Challenges in Physiology

dr. dolittle — Fri, 10 Oct 2014 17:13:31 +0000

Wednesday: Grand Challenges in Physiology

Image from the American Physiological Society's website.
http://www.the-aps.org/mm/Conferences/APS-Conferences/2014-Conferences/…

Wednesday was the last day of the meeting that culminated in a closing banquet with an awards session to honor students who had exceptional presentations. What an impressive group of young comparative physiologists! The plenary lecture was given by Dr. Steven Chown (Monash Univ, Australia). He spoke about climate change forecasts and continuing environmental changes and how important it is to understand how animals adapt to changing conditions in order to make ecophysiological predictions.

Other highlights from throughout the final day of the meeting included:

A series of lectures that were focused on understanding and modeling responses to stress in animals to help predict when populations may be at risk of declining before it happens.

Finkelstein A, Derdikman D, Rubin A, Foerster JN, Las L, Ulanovsky N (Weizmann Inst of Sci; Israel Inst of Tech). There are neurons in brain that are called 'head-direction cells'. These are responsible for informing an animal when their head is oriented in a specific direction, which is important for orientation when navigating in a three-dimensional space.

Dr. John Cockrem (Massey Univ, New Zealand) spoke about how birds release the hormone corticosterone when they perceive or experience a threat. This response to stress can vary between birds. Birds that have lower stress responses (indicated by lower corticosterone release) are considered to be more successful under predictable conditions. In contrast, birds with large stress responses may be more successful under unpredictable or changing conditions, which may help them to deal with environmental changes better than birds with lower stress responses.

13-lined ground squirrel hibernation is broken up by intermittent bouts of arousal during which time the animal wakes up from torpor (See figure below).

Figure 1: showing hibernation of a 13-line ground squirrel with intermittent bouts of arousal and torpor. March 16, 2009, doi:
10.1113/jphysiol.2008.167692

Ballinger M, Napolitano M, Bjork J, Andrews MT (Univ Minnesota) discussed how brown fat (i.e. brown adipose tissue), which the animals build up before hibernation, is important for producing heat that enables them to have these intermittent bouts of arousal. Notice in the image above how the body temperature ranges from ~37degC when they are awake down to only about 3-5degC when they are in torpor.

Grabek K, Hesselberth J, Barsh G, Behn CD, Martin S (Univ Colorado (Denver); HudsonAlpha Inst Biotech) also discussed how brown fat cycles between a more dormant state (torpor) to an active state (arousal) to match the metabolism of the whole animal during those phases. They discovered that the genome of the brown fat actually changes during these different phases to allow for the rapid production of various proteins needed to produce heat (thermogenesis).

Wone B, Ojha J, Davidowitz (Univ Nevada-Reno; Univ Arizona) presented data that showed hawkmoths (Manduca sexta) are good models of disease and aging in skeletal muscle because their flight muscles are similar, metabolically-speaking, to vertebrate skeletal muscle. Who knew?

Image of Manduca sexta from Wikimedia Commons.

dr. dolittle Fri, 10/10/2014 - 13:13

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Scaredy snakes?

dr. dolittle — Thu, 21 Aug 2014 23:20:06 +0000

Scaredy snakes?

Image of a green tree python from www.kids.britannica.com
J.H. Pete Carmichael—The Image Bank/Getty Images

Dr. Greg Byrnes (Siena College, Loudonville, NY) and Dr. Bruce Jayne (University of Cincinnati, OH) discovered that snakes use more force than is necessary to support their weight when climbing. To climb, snakes rely on friction and repeatedly contract and extend their bodies, a process called concertina locomotion. To study the forces generated by snakes during this type of locomotion, the researchers constructed a vertical cylinder that was covered with textured tennis racket tape (for friction) and pressure sensors. They also calculated the minimum gripping force (i.e. coefficient of friction between the snake and the surface) exerted by the snakes to avoid falling off by putting the snakes on a flat surface covered with the textured tape and slowly tilting the board until the snake began to slip.

What they found was a range of responses in which some snakes used minimum force to climb the vertical tube whereas others used almost 20 times the force needed to prevent slipping. Study author Byrnes was quoted in LiveScience saying, "The vast majority of time, the safety factor was between 2.5 and 5. They are using a force that's not at their maximum, but not at their minimum, either." Perhaps they are gripping tightly to avoid falling off and having to climb back up or perhaps a tight grip is important to avoid predators or to attack prey. Whatever the reason, the study authors mentioned that the excess gripping force does not likely cost the animals too much overall in terms of energy expenditure.

Similar to snakes, the authors report that humans typically grip objects at 2-4 times the amount of force required to support their weight. Personally, I think I am closer to 4 times.

Sources:

LiveScience

Byrnes G, Jayne BC. Gripping during climbing of arboreal snakes may be safe but not economical. Biology Letters. 10(8): 20140434, 2014.

dr. dolittle Thu, 08/21/2014 - 19:20

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One night I watched a corn snake climb a vertical 2" square aluminum pole. Sounds easy, just wrap around it and squeeze as you climb. But this snake didn't wrap around the pole. It adopted an S-shape across a flat and hung a bit of body over the edge to give it a gripping surface. By essentially forming a series of biological C-clamps as grips it advanced rapidly up the smooth pole.

A protein that improves exercise capacity

dr. dolittle — Fri, 01 Aug 2014 15:49:10 +0000

A protein that improves exercise capacity

Cartoon image from www.teenwritersblog.com

Physiologist Laurie Goodyear (Joslin Diabetes Center, Harvard Medical School, MA) and her colleagues recently published a study in the American Journal of Physiology that shows how overexpressing a protein can increase exercise capacity. The protein of interest was tribbles homolog 3 (TRB3), which is a mammalian form of the tribbles protein found in fruit flies (aka: Drosophila). Prior to this study, data suggested that TRB3 plays a role in metabolism so Dr. Goodyear's team decided to examine this more closely in skeletal muscle, which is a major contributor to metabolism. What they discovered is that exercise increases the expression of the protein by 2.5 times in the triceps muscle of normal mice and that exercise capacity was significantly increased in mice that genetically overexpress the protein in their muscles. Moreover the muscles of the overexpressing mice were found to contain more oxidative, fatigue-resistant muscle fibers that would promote this enhanced exercise capacity.

I think I need more TRB3 in my muscles.

Source:

An D, Lessard SJ, Toyoda T, Lee M, Koh H, Qi L, Hirshman MF, Goodyear LJ. Overexpression of TRB3 in muscle alters muscle fiber types and improves exercise capacity in mice. American Journal of Physiology- Regulatory, Integrative and Comparative Physiology. 306: R925-R933, 2014.

dr. dolittle Fri, 08/01/2014 - 11:49

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And insulin resistance alas
http://www.ncbi.nlm.nih.gov/pubmed/12791994

How do I get more TRB3 in my muscles

What do a hummingbird and chicken have in common?

dr. dolittle — Thu, 17 Jul 2014 12:05:37 +0000

What do a hummingbird and chicken have in common?

Brandy Velten (doctoral student) and Dr. Kenneth Welch (Comparative Physiologist) from the University of Toronto wanted to know whether birds with very different speeds at which they flaps their wings (i.e. wingbeat frequencies) had correspondingly varying types of myosin proteins in their muscles. Their findings were published in the American Journal of Physiology last month.

In their study they compared ruby-throated hummingbirds and zebra finches which reportedly have some of the highest wingbeat frequencies (20-60Hz). As you can imagine, their flight muscles are made up of almost exclusively of muscle fibers that contract very fast (i.e. fast twitch). Whereas a chicken's breast muscle (i.e. pectoralis) is composed of mostly slow-twitch muscle fibers that are more important in controlling things like posture. Myosin heavy chain (MHC) is very important in regulating the ability for a muscle to contract (for a review of myosin, see the video at the end of this post). The type of MHC varies depending on whether a muscle is mainly slow or fast twitch. It was these variations in the MHC protein that this study explored in the following birds:

Ruby-throated hummingbirds (Archilochus colubris)

Image of Ruby-throated hummingbird from Wikimedia Commons.

Zebra Finches (Taeniopugia guttata)

Image of zebra finches from Wikimedia commons.

Because some collectors nearby left behind the carcass of a juvenile yellow-bellied sapsucker (Sphyrapicus varius) and an adult house sparrow (Passer domesticus), these species were included as well since their wingbeats are not as fast, which made for a nice comparison.

What they found was really interesting. Even though each of these species had varying wingbeat frequencies, the pectoralis and supracoracoideus flight muscles of these birds had only one type of MHC protein, which turned out to be the same fast type that is found in chicken pectoralis muscles, not exactly a bird setting any records with its flying abilities. What these findings mean is that this particular MHC protein is important for general powered flight. Therefore, the structural properties of the MHC protein or other proteins that it interacts with may be more important in determining whether a bird can be an extraordinary flyer like a hummingbird or an occasional short distance "flyer" like a chicken.

Comic from: www.cartoonstock.com

For a review on muscle contraction and what in the world myosin is, check out this YouTube video:

Source:
Velten BP, Welch KC. Myosin heavy-chain isoforms in the flight and leg muscles of hummingbirds and zebra finches. Am J Physiol Regul Integr Comp Physiol. 306: R845–R851, 2014. doi:10.1152/ajpregu.00041.2014

dr. dolittle Thu, 07/17/2014 - 08:05

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Puerto Rico Physiological Society meeting

dr. dolittle — Fri, 24 Jan 2014 02:04:39 +0000

Puerto Rico Physiological Society meeting

I am very excited to report that the Puerto Rico Physiological Society will be hosting their 4th annual meeting, "Exercise Physiology: From Molecules to Systems" on February 8th.

PRPS 2014 Save the Date

Last year's meeting was focused on mitochondria and was a big success. This year's meeting is shaping up to be similarly successful.

dr. dolittle Thu, 01/23/2014 - 21:04

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The Original Jocks

zooillogix — Thu, 02 Apr 2009 15:51:30 +0000

The Original Jocks

by Katie the Lowly Intern

You might recall this gentle soul who got her face gnawed off by a chimp in February. I won't even begin to sift through the big ball of bizarre that story is, but it does lead to an interesting discussion concerning exactly where apes get enough strength to go around mauling humans. Biologists agree that a great ape's muscle structure is better, faster, stronger than our measly muscles. However, Alan Walker, a professor of Biology at Penn State just published an article in Current Anthropology that looks at another possible contributing factor.

He makes the argument that not only are great apes at a structural advantage, but perhaps their neurological hardwiring has something to do with their disproportionate super strength (4x that of humans*). If you buy into evolution, then his hypothesis seems to make some sense.

We, as humans, generally have very fine-tuned motor skills that make it easier for us to do human stuff like tie shoe laces, dial phone numbers, and lightly caress a stranger's soft hair without being detected. But all a monkey does is jump around and fling poop. In other words, we have the ability to control fewer muscle fibers as we complete complex tasks, while apes control more muscle fibers at one time for simpler tasks. Walker backs up some of his claims by referencing a primatologist, Ann MacLarnon (avatar name: chimpANN_Z). She found that chimps have a lot less grey matter in their spinal chords than humans. And wouldn't you know, spinal cord grey matter houses tons of motor nuerons. Which means chimps have poorer fine motor skills, but more muscle fibers working together to perform the same action. Which means their muscle movements are less refined, but more powerful. Which means we win in needle threading contests, but not in limb rending.

*I should say most humans. Here is a photo taken of me at the beach last summer opening a jar of jam for a helpless chimp.

zooillogix Thu, 04/02/2009 - 11:51

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How... how did you know about the hair stroking?! I was so careful!

Ahem. Understand that my knowledge of neurology, physiology, and neurophysiology was never great and is out of date. That out of the way, is it possible that there's a switch in us that causes a reversion to something like this ape model of muscle control, as a means of explaining feats of strength under stress? Sure, most of it is the adrenal glands whispering sweet nothings to you, telling you "No, of course that tearing crackle noise wasn't your back. It's probably just free bib night at the Kenny Roger's Roasters.", but it was a thought that just happened to strike me.

Actually... yeah. A quote from Mr. Walker:
"Add to this the effect of severe electric shock, where people are often thrown violently by their own extreme muscle contraction, and it is clear that we do not contract all our muscle fibers at once... So there might be a degree of cerebral inhibition in people that prevents them from damaging their muscular system that is not present, or not present to the same degree, in great apes."

smart, sexy and with mild stalking habits!!!! marry me katie x

She fits right in. Welcome aboard.

You ran into a chimpanzee with a tail at the beach, and the jar of jam was the only thing that caught your attention? Cryptozoology fail.

Neato. Thanks for sharing!

Ha. Excellent, nice write up. Can't wait to read more. An ape is what, about 4 times stronger then a human?

brendan
www.wildramblings.com

No, of course that tearing crackle noise wasn't your back. It's probably just free bib night at the Kenny Roger's Roasters.", but it was a thought that just happened to strike me.

Interesting that you have a chimp in a gi. It seems likely to me that some of the more esoteric martial arts have training methods for accessing that strength (often called "hysterical strength"). It may be that special cerebral processes are required to get all the nerves to fire together.

The might be a degree of cerebral inhibition in people that prevents them from damaging their muscular system that is not present. oky?

Wooww karate maymun :)

of ya offfff

ama naz yaptin yafrum ya

hay a.k senin ben yaaa

You ran into a chimpanzee with a tail at the beach, and the jar of jam was the only thing that caught your attention? Cryptozoology fail.

where people are often thrown violently by their own extreme muscle contraction, and it is clear that we do not contract all our muscle fibers at once

How... how did you know about the hair stroking?! I was so careful!

thankÂ´s for this interesting topic