Recent Publication: Biology Team

Dr. Michael Butcher, Associate Professor in Biological Science, in collaboration with Dr. Gary Walker, Chairperson and Professor of Biological Sciences, Mr. Julio “Ed” Budde, and student Dylan Thomas published a research article in Journal of Applied Physiology in September 2017.

 

Title: Ontogeny of myosin isoform expression and prehensile function in the tail of the gray short-tailed opossum (Monodelphis domestica)

Authors: Dylan R. Thomas, Brad A. Chadwell, Gary R. Walker, Julio E. Budde, John L. VandeBerg, Michael T. Butcher

 

Abstract:

Terrestrial opossums use their semiprehensile tail for grasping nesting materials as opposed to arboreal maneuvering. We relate the development of this adaptive behavior with ontogenetic changes in myosin heavy chain (MHC) isoform expression from 21 days to adulthood. Monodelphis domestica is expected to demonstrate a progressive ability to flex the distal tail up to age 7 mo, when it should exhibit routine nest construction. We hypothesize that juvenile stages (3–7 mo) will be characterized by retention of the neonatal isoform (MHC-Neo), along with predominant expression of fast MHC-2X and -2B, which will transition into greater MHC-1β and -2A isoform content as development progresses. This hypothesis was tested using Q-PCR to quantify and compare gene expression of each isoform with its protein content determined by gel electrophoresis and densitometry. These data were correlated with nesting activity in an age-matched sample of each age group studied. Shifts in regulation of MHC gene transcripts matched well with isoform expression. Notably, mRNA for MHC-Neo and -2B decrease, resulting in little-to-no isoform translation after age 7 mo, whereas mRNA for MHC-1β and -2A increase, and this corresponds with subtle increases in content for these isoforms into late adulthood. Despite the tail remaining intrinsically fast-contracting, a critical growth period for isoform transition is observed between 7 and 13 mo, correlating primarily with use of the tail during nesting activities. Functional transitions in MHC isoforms and fiber type properties may be associated with muscle “tuning” repetitive nest remodeling tasks requiring sustained contractions of the caudal flexors.

 

Full article link:

http://jap.physiology.org/content/123/3/513

Recent Publication: Dr. Michael Butcher & Zachary Glenn

Dr. Michael Butcher, Associate Professor in Biological Science, in collaboration with biology student Zachary Glenn, published a research article in Journal of Mammalian Evolution in September 2017.

 

Title: Architectural Properties of Sloth Forelimb Muscles (Pilosa: Bradypodidae)

Authors: Rachel A. Olson, Zachary D. Glenn, Rebecca N. Cliffe, Michael T. Butcher

 

Abstract:

Tree sloths have reduced skeletal muscle mass, and yet they are able to perform suspensory behaviors that require both strength and fatigue resistance to suspend their body mass for extended periods of time. The muscle architecture of sloths is hypothesized to be modified in ways that will enhance force production to compensate for this reduction in limb muscle mass. Our objective is to test this hypothesis by quantifying architecture properties in the forelimb musculature of the brown-throated three-toed sloth (Bradypus variegatus: N = 4). We evaluated architecture from 52 forelimb muscles by measuring muscle moment arm (rm), muscle mass (MM), belly length (ML), fascicle length (LF), pennation angle (θ), and physiological cross-sectional area (PCSA), and these metrics were used to estimate isometric force, joint torque, and power. Overall, the musculature becomes progressively more pennate from the extrinsic to intrinsic regions of the forelimb, and the flexors are more well developed than the extensors as predicted. However, most muscles are indicative of a mechanical design for fast joint rotational velocity instead of large joint torque (i.e., strength), although certain large, parallel-fibered shoulder (e.g., m. latissimus dorsi) and elbow (e.g., m. brachioradialis) flexors are capable of producing appreciable torques by having elongated moment arms. This type of functional tradeoff between joint rotational velocity and mechanical advantage is further exemplified by muscle gearing in Bradypus that pairs synergistic muscles with opposing LF/rm ratios in each functional group. These properties are suggested to facilitate the slow, controlled movements in sloths. In addition, the carpal/digital flexors have variable architectural properties, but their collective PCSA and joint torque indicates the capability for maintaining grip force and carpal stability while distributing load from the manus to the shoulder. The observed specializations provide a basis for understanding sustained suspension in sloths.

Full article link:

https://link.springer.com/article/10.1007/s10914-017-9411-z

Biomedical Research Series: Dr. Michael Butcher

Within the Department of Biological Sciences at Youngstown State University, there are many areas of research being explored by faculty and students alike. In a monthly series, we will highlight faculty research that covers various aspects of biomedical efforts from DNA to bacteria, fungi, and more.

Dr. Michael Butcher is an Associate Professor of Biological Sciences at YSU. He earned his PhD in Zoology from the University of Calgary. Afterward, he completed a two-year NSF post-doctoral fellowship at Clemson University before becoming a full-time professor at YSU.

At YSU, Dr. Butcher conducts three different types of research with assistance from multiple graduate and undergraduate students. The main focuses of his laboratory research are the mechanical properties and shape of limb bones, fiber architecture and force production in the limb muscles, and development of muscle fiber types. His most recent work involves studies of muscle form and contraction activity in tree sloths.

Every other year, Dr. Butcher has traveled to The Sloth Sanctuary in Limón, Costa Rica. This gives him the opportunity to study species of two-toed and three-toed sloths.

On his most recent trip, he and his research team visualized live muscle contractions of the sloths using implanted fine wire electrodes. They recorded muscle activity while sloths performed combinations of walking, climbing, and hanging exercises. In addition, Dr. Butcher and his team conducted very detailed dissections on cadaver sloths to learn about their muscle architecture.

This slideshow requires JavaScript.

“What we do is take geometric measurements of the muscles,” Butcher said. “For example, how long is the muscle belly, how long are the muscle fibers, at what angle are the muscle fibers? Then we apply a couple basic calculations.”

They could then estimate the force, power, and torque (strength) properties of sloth muscles. Dr. Butcher considers this approach to the study of muscle form and function “simple, but elegant.”

To understand his research interests, it is important to know some of the unusual characteristics of a sloth.

“Why a sloth?” Dr. Butcher was asked. “Because they’re old and interesting mammals that do something really different from what humans are capable of doing.”

In a sloth’s body, there is only about 24% muscle mass. Dr. Butcher and his students are finding that their muscles have a high tolerance for lactic acid and rarely fatigue, unlike skeletal muscles in humans. Much to his surprise, Dr. Butcher is also learning that sloths primarily use anaerobic mechanisms to allow them to conserve energy and resist fatigue. This contributes to a sloth’s ability to hang from tree limbs for extended periods of time.

Other factors that relate to the strength and stamina of sloths are lower body temperature, lower metabolism, and slower digestion than most placental mammals.

“Sloths also have a network of blood vessels in their forearms that lowers the temperature of the muscles,” Butcher said. “This allows the muscles to remain strongly contracted for gripping branches while using energy at a slower rate.”

With these distinctive characteristics, sloths can conserve a tremendous amount of energy. For this very reason, Dr. Butcher finds sloth research remarkably insightful.

Dr. Butcher does not simply perform research to learn more about muscle structure-function in sloths, but rather to give further evidence of the performance range of muscles, in general. He wants to continue studying how muscles are put together and how they work, as functionality is diverse for animals depending on their lifestyle.

While this research has medical applications such as bioengineering artificial muscles and limbs, Dr. Butcher remains committed to fundamental science where his findings contribute towards education in the scientific community, future textbooks, and enhancement of the courses that he teaches at YSU.

Dr. Butcher stresses the immense contribution from his students. He believes that they are vital to his research efforts. To further his studies in primitive mammals Dr. Butcher plans to travel to Argentina this fall to investigate muscle properties in rare species of armadillos.

Faculty Faction: Dr. Michael Butcher

Dr. Michael T. Butcher
Dr. Michael Butcher poses with a biology academic poster.

Youngstown State University collects all sorts of people as students, faculty, and professors. Each of these people has something specific and unique to offer the community and the university. Dr. Michael Butcher, assistant professor of anatomy and physiology, has been an essential part of the research initiative in the Department of Biological Sciences for the last five years.

Michael feels at home in the Biological Sciences department; the position is what brought him to the Youngstown area.

“The Department of Biological Sciences was a good fit for me and they were very supportive of my research program,” Michael says.

Dr. Butcher studied Continue reading “Faculty Faction: Dr. Michael Butcher”