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Summer 2011 Research Projects

 

  • Bean | Flowers
  • Berger | Iovine
  • Itzkowitz | Samollow
  • Jedlicka | Coulter
  • Tatic-Lucic | Perry

The human sperm equatorial segment:
composition and roles in sperm function

 

Bean/Flowers Team 2011
standing: Team Leaders, Robert Flowers, Ph.D. (Chemistry), Barry Bean, Ph.D. (Biological Sciences)
sitting: Cody Molnar, Maria Santoyo Llamas, Stephanie Mack, Kamonrat Phopin, Ifeoluwa Olokode

Team Leaders:

Barry Bean, Ph.D. (Biological Sciences)
Robert Flowers, Ph.D. (Chemistry)

Graduate Student:

Kamonrat Phopin (Biological Sciences)

Undergraduate Students:

Maria Santoyo Llamas
Stephanie Mack
Cody Molnar
Ifeoluwa Olokode

Description of Project:

Human sperm contain a unique membranous structure in the middle of the sperm head called the equatorial segment. This subcellular organelle is thought to have distinctive and essential functions in the intimate interactions between sperm and egg during fertilization.  Over the years, some components of the equatorial segment have been identified, but the organelle has not been purified or characterized as an integrated structure.  The details of its organization and function invite refined investigation.  Because it probably has essential but poorly understood roles in the continuity of our species, the sperm equatorial segment is a compelling focus for research.  Recent studies at Lehigh have shown that the enzyme SMALF [Sperm Membrane associated Alpha-L-Fucosidase] is enriched within the equatorial segment, and it has important roles in fertilization and early embryo development in animal systems.  Independent studies within our earlier collaboration here have also identified novel compounds, including fluorous surfactants, that may be useful for the selective extraction and chemical dissection of sperm.  We hope to use the distinctive tools at hand to advance insights into the structure and functions of the equatorial segment, potentially including subcellular fractionation and purification of this organelle.

Identification of Neuropilin-plexin hetero-oligomerization domains

 

Berger/Iovine Team - 2011
standing: Rachel Barton, Team Leaders, Bryan Berger, Ph.D. (Chemical Engineering), M. Kathryn Iovine, Ph.D. (Biological Sciences), Pin Chuan Su, Joyita Bhadra
sitting: Silas Simotwo, Diego Liriano, Dana DeSantis, Theresa Collins, Justin Nice

Team Leaders:

Bryan Berger, Ph.D. (Chemical Engineering)
M. Kathryn Iovine, Ph.D. (Biological Sciences)

Graduate Students:

Joyita Bhadra (Biological Sciences)
Pin-Chuan Su (Chemical Engineering)

Undergraduate Students:

Theresa Collins
Dana DeSantis
Diego Liriano
Justin Nice
Silas Simotwo

 

Description of Project:

The semaphorins are a large family of extracellular signaling molecules that induce a wide diversity of cellular outcomes throughout development, including cell adhesion, cell migration, tissue patterning, cell proliferation, viability, and changes in the cytoskeleton. Dysregulation of semaphorin signaling has been strongly linked to a number of diseases, including lung cancer and CHARGE syndrome, as well as an etiological factor in congenital heart defects. Semaphorins bind directly to a family of type I transmembrane co-receptors, the plexins (plex) and neuropilins (nrp), in order to transduce signals across cell membranes. Although it is known that plexins and neuropilins oligomerize at the cell surface, the stoichiometry of the co-receptor complex formed upon semaphorin binding, and how changes in co-receptor oligomeric state alter transmembrane signal transduction, are unclear.

The goals of this project are twofold:

(1) determine if receptor composition mediates distinct downstream cellular outcomes using a heterologous system,

(2) to define the domains of the receptor and co-receptors responsible for heterooligomerization.

Completion of the aims of this proposal will provide insights into how distinct intracellular signaling events are initiated by a common signal (i.e. Sema3d) and will reveal important biophysical properties that regulate receptor heterooligomerization during signal transduction.

Species recognition and hybridization in
four Carribbean Damselfish (Stegastes)

Itzkowitz/Samollow Team 2011
standing: Vance Imhoff, Team Leader Murray Itzkowitz, Ph.D. (Biological Sciences), Andrew Black
sitting: Ryan Norkett, Patrick Osborn, Daryl Watson, Sherwood Benavides

Team Leaders:

Murray Itzkowitz, Ph.D. (Biological Sciences)
Paul Samollow, Ph.D. (Department of Veterinarian Integrative Biosciences, Texas A&M Univ.)

Graduate Students:

Andrew Black (Biological Sciences)
Vance Imhoff (Biological Sciences)

Undergraduate Students:

Sherwood Benavides
Ryan Norkett
Patrick Osborn
Daryl Watson

 

Description of Project:

This study is designed to test whether species that form hybrids are more likely to treat each other as conspecifics than species that typically do not interbreed. In Jamaica, we know that the dusky damselfish (Stegastes adustus) and the longfin damselfish (S. diencaeous) have formed hybrids while the two other closely related species, the beaugregory (S. lecostictus) and the three-spot (S. planifrons) do not. Interestingly, the formation of hybrids between the longfin and the dusky appears to be island specific. That is, we recorded no hybrids in Barbados.

Using both Jamaica and Barbados, we will use behavioral and genetic tests to determine whether the presence or absence of hybrids can be related to species recognition and whether this recognition is related to a specific location. We have devised a simple series of behavioral tests that have been shown to be useful in testing the ability of a species to differentiate conspecifics from heterospecific individuals.

Because hybrids have highly variablel phenotypes, it is essential to use molecular tests to determine species status. Students will take small tissue samples from the fish and take them back to Lehigh University where they will be trained to perform genetic analyses.

Effects of polymer molecular orientation
and biodegradation on stem cell differentiation

 

Coulter/Jedlicka Team - 2011
standing: Team Leaders John Coulter, Ph.D. (Mechanical Engineering), Sabrina Jedlicka, Ph.D. (Materials Science & Engineering), Courtney LeBlon
kneeling: Jordan Rejaud, Christopher White

Team Leaders:

Sabrina Jedlicka, Ph.D. (Materials Science & Engineering)
John Coulter, Ph.D. (Mechanical Engineering & Mechanics)

Graduate Student:

Courtney LeBlon (Engineering)

Undergraduate Students:

Jordan Rejaud
Christopher White

 

Description of Project:

Tissue engineering is a rapidly expanding field that promises to regrow, restore, and help maintain new tissues to treat disease and injury. For a tissue engineering scaffold to succeed, several critical factors are required, including material biocompatibility, cell adhesion and ingrowth, and a suitable biodegradation rate. Scaffolds should ideally possess some properties that are similar to the natural tissue environment, including extracellular matrix organization, material elasticity, and the ability for cells to communicate. This project will attempt to mimic ECM molecular alignment by developing scaffolds with controllable polymeric molecular orientation. We hypothesize that molecular orientation will augment cell fate and biodegradation rate of the material. Students will participate in experiments in manufacturing technology, polymer characterization, biodegradation, and cell biology.

Development of a multielectrode array (MEA) based on
active recruiting of cells and formation
of mechanically confined neurons

 

Tatic-Lucic/Perry team
standing: Tianyi Zhou, Team Leader Svetlana Tatic-Lucic, Ph.D. (Electrical & Computer Engineering), Markus Gnerlich
sitting: Peter Wallerson, Christina Chung, Lauren Kraft, Bryan Antigua

Team Leaders:

Svetlana Tatic-Lucic, Ph.D. (Electrical & Computer Engineering)
Susan Perry, Ph.D. (Chemical Engineering)

Graduate Students:

Markus Gnerlich (Electrical & Computer Engineering)
Tianyi Zhou (Electrical & Computer Engineering)

Undergraduate Students:

Bryan Antigua
Christina Chung
Lauren Kraft
Peter Wallerson

 

Description of Project:

Learning and memory involve the interaction of complex networks of neurons. While much progress has been made in this area of neurobiology, a full understanding of the cellular processes underlying thought and memory, including those guiding the generation of these networks and the communication between individual neurons, remains elusive. One approach to investigate neuronal activity is to grow defined arrays of neurons on a substrate containing built-in electrodes capable of sensing the electrical signals generated by individual neurons. These multielectrode arrays (MEAs) are also capable of providing electrical stimulation in a regulated manner followed by recording of the resulting electrical activity.

This interdisciplinary project is a collaborative effort between Svetlana Tatic-Lucic (Electrical and Computer Engineering and Bioengineering) and Susan Perry (Bioengineering). The focus of our 2011 BDSI project is to develop a novel type of MEA, which utilizes both electrical and mechanical methods to recruit and confine neurons to specific, electrode-containing locations. Isolating individual neurons at specific locations within a predefined substrate that contains special channels for neurites will subsequently allow for predictable neurite outgrowth and ultimately the formation of a patterned neuronal network. In this project, students will aid in the design of photomasks, learn hands-on clean room fabrication techniques, assist during the fabrication process of novel MEA chips, and package the MEA devices.  Using basic cell culturing techniques, students will also culture patterned neuronal networks on their fabricated substrates, with the ultimate goal of recording electrical activity from the neurons.

 

 

 

 
     
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The Biosystems Dynamics Summer Institute is sponsored by a grant from the
Howard Hughes Medical Institute
to Lehigh University

 
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