Faculty Profiles: Darrell Wiens
Professor: Doing research the best way to learn science
Darrell Wiens most often teaches anatomy, physiology and developmental biology, although he
has been known to teach comparative anatomy of vertebrates, molecular biology of the cell and careers in the life sciences, among other things. The professor of biology, who has been at UNI since 1989, believes that the most fundamental thing about teaching is the connection between teacher and student.
“Working with students is one of the most enjoyable things I do, and I think I was born to teach this way,” Wiens said. “There is no finer way to learn science than to just do it. When we are all working together in the ‘OR,’ carrying out dissections of embryonic organs so tiny that they look like specks to the native eye, with a CD playing in the background and fertile eggs getting opened and cultures getting set up . . . well, that’s a grand time. And when tissue development happens right before your eyes and it looks like magic—really, what can compare with that?”
Wiens’ research area, in which his students are active participants, is developmental biology, specifically aspects of the early development of two organ systems: the central nervous system itself and its contribution to the development of the heart and its early outflow vessels. In these studies he uses the chick embryo as a model animal embryo. For research on the effects of altered gravitational force on the early development of the heart, he uses the amphibian African clawed frog.
Students Kate Olson, Selena Losee, Erin O’Kane, Kayla Olson and Alexandra DeWitt have been studying secondary neurulation. Neurulation is when the neural tube is transformed into the primitive structures that will later develop into the central nervous system. With chick embryos, the cranial and most of the trunk portions of the neural tube are formed by primary neurulation, and the lower portion of the neural tube is formed by secondary neurulation. In the latter case, unorganized cells in the tail bud region become polarized and then coalesce into a solid medullary cord, which cavitates. The secondary neural tube eventually joins to the primary in an overlap zone, and the region eventually develops into the lumbrosacral spinal cord with surrounding vertebrae and nerves. The formation of the prospective medullary cord from the tail bud requires that some of the unorganized cells begin to form junctions with each other. A goal of the research is to discover what specific types of junctions aid in the formation of the neural tube by identifying the molecules associated with specific types of junctions. With regard to this, the researchers are looking at cadherin, a calcium-dependent transmembrane cell surface protein that is a major component of many cell-cell adhesions.
Student Kayla Olson is also examining the role of gap junction protein connexin43 in secondary neurulation. To align around cavities, cells must first become polarized, adhere to one another and synthesize specific molecules that allow them to create junctions with one another. Olson is studying gap junctions as the cells interact to form them and how they are needed among the cells.
Using tissue culture to study the cavitation process during secondary neurulation, student Alexandra DeWitt employed a rotating wall vessel as a bioreactor that exposes all surfaces of tissues to the tissue culture medium as they rotate suspended in orbit. The hope is that the rotating wall vessel will provide a new model system to investigate the role of cadherins.
Neural crest cells in vertebrate embryos are found between the neural tube and epidermis, emerging just as the neural folds close dorsally to form the neural tube. These cells become migratory. Student researchers—Amanda Clubine, Anthony Mwakikunga, Chelsea Reinhard and Jordan Gurtner—have studied the migration of the neural crest cells that move outward and downward from the hindbrain region of the neural tube because these cells migrate to the heart and its outflow vessels, taking up residence there to form, for example, the septum that will divide the ventral aorta into aortic loop and pulmonary artery. The researchers hypothesized that homocysteine, an amino acid that normally circulates in the blood, changes the migration of neural crest cells in developing embryos. Their findings supported their hypothesis that homocysteine adjusts neural crest cells for greater adhesion and migration. Neural crest cells exposed to homocysteine may thus show misdirected or mistimed migration to the heart outflow region.
Student Bryce Duchman studied the effect of hypergravity on growth and cardiac hypertrophy (excessive enlargement) in the African clawed frog. Hypergravity was simulated through centrifugation of the embryos in the test group. Although no significant differences in behavior or mortality were found between the test and control groups, body length was significantly reduced, by an average of 6.8%, and ventricle size was significantly increased in embryos in the test group.
In addition to his strong interest in teaching and research, Wiens has consistently participated in and helped to direct the biology summer undergraduate research program, in which students conduct research with faculty mentors during the summer months and then report on that research at a conference in August. He also serves as the faculty adviser to the pre-med club and the pre-vet club.
Wiens has been recognized with Dean’s Awards--for Outstanding Faculty Achievement and for Superior Achievement in Research—by the college, a Faculty Excellence Award by the State Board of Regents and an Excellence in Teaching Award from Tri Beta Biological Honor Society. His research has been funded by the American Heart Association, NASA and the National Science Foundation, among others, and he is the author of numerous publications in peer-reviewed scientific journals.