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Bones and Beyond

Spring 2013

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The focus of Dr. Maria Squire’s research has been on what she calls “the most fascinating organ in a vertebrate organism: bones.” More specifically, the associate professor of biology is interested in determining how much bone tissue is present, the quantity, the tissue, and factors such as environment.

She has always had an interest in the musculoskeletal system, but her passion for studying bone began when she was a graduate student. During her graduate studies, she examined bone loss, osteopenia, and the influence that genetics and gender have on the development and severity of osteopenia. She used a mouse model to study bone loss that resulted from a lack of weight-bearing, research that was funded by a NASA Graduate Student Researchers Program Fellowship.

Since her graduate school days, Dr. Squire’s research interests continue to center around quantifying bone tissue and examining its microarchitecture, but her focus has more recently shifted toward characterizing and quantifying changes in bone quantity and architecture relative to events throughout the annual cycle of a migrating bird. For these studies, she has had the opportunity to collaborate with a number of scientists around the country and at The University of Scranton. She has worked with some of the University’s undergraduate student researchers and one local high school student who conducted research with her in summer 2012.

One of the most exciting developments and directions that her research has taken in the last few years has been related to the examination of medullary bone in breeding female passerine birds. Medullary bone is a type of primary bone tissue that can serve as a calcium reservoir. It is laid down quickly and can also be broken down relatively quickly to release calcium and make it available for use by the body. This can be particularly crucial for female birds during the breeding season as almost 98 percent of the dry mass of an eggshell is comprised of calcium hydroxyapatite, which is the primary mineral component of bone. She came upon the medullary bone as a result of scanning bones gathered from birds collected during spring migration at breeding grounds and during fall migration.

Dr. Squire and her collaborators, along with an undergraduate student, published a study in The Wilson Journal of Ornithology in 2011 that demonstrates the presence of this medullary bone tissue in breeding female passerine birds and its absence in post-breeding females and those females that were collected during all other non-breeding phases of their annual cycle. In an ongoing study, which was recently presented at the Society of Comparative and Integrative Biology annual meeting in January 2013, they showed that the presence of medullary bone is influenced, at least in part, by estrogen levels and may also be related to the stage of the female bird’s progress toward laying an egg. While her continuing research will examine the timing of medullary bone formation relative to egg-laying, she and her fellow researchers are also interested in further investigating what factors influence its formation. They plan to investigate the specific role of medullary bone during eggshell formation in these birds.

Another area of focus in Dr. Squire’s research is understanding the influence that events related to migration may have on bone quantity and microarchitecture. Researchers know that there are changes that take place within many organ systems in birds during their preparation for migration, as well as during migration. She plans to compare bone quantity and microarchitecture among birds collected prior to migration, upon arrival at the breeding grounds, and just prior to departure from the breeding grounds for fall migration in order to determine what, if any, effect migration might have on bone tissue.

None of this research would be possible without the Major Research Instrumentation grant that she obtained from the National Science Foundation to acquire a micro-computed tomography, microCT scanner at Scranton. MicroCT scanning is a state-of-the-art technique that utilizes an X-ray source and a CCD array detector to create high-resolution, micron-level images of the tissue being scanned. Having this state-of-the-art instrument on campus has allowed Dr. Squire and her students the opportunity to visualize and analyze the quantity and microarchitecture of bones in a non-destructive way and advance understanding of a previously little-studied process.

Author

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Maria Squire, Ph.D.
Biology
maria.squire@scranton.edu
570.941-4742