Archive for August, 2012

Jessica Oya, our High School Science Teacher, Returns!!

This summer we had the fortune of having Jessica Oya, the high school teacher from the Life Academy of Health and Biosciences in Oakland, come work in our lab again as part of the IISME program.  This year, Jessica worked with Jack on a project involving zebrafish development and learned how to fix and stain zebrafish embroys for various proteins.  In addition, she set up a curriculum for her chemistry class, incorporating some of the techniques she learned in our lab to pass on to her students.  She now has extensive experience teaching biology, physics, and chemistry at the high school level, with several demonstrations and experiments that she learned while working in our lab.

From my limited experience teaching (having just TA’ed 1 class so far), I learned both the difficulties and rewards of teaching.  And after visiting Jessica at her school and seeing her in action, I realized the expertise she has developed over the last several years.  I have often thought how awesome it would be to go back to high school (preferably my old high school) and teach chemistry.  My AP chemistry teacher in high school was an excellent teacher, so good that he was also our high school wrestling coach.  After the AP exams, he had the class participate in a competition to determine who was the best wrestler…  But from him, I learned the importance of having a teacher who spends the effort making sure every student understands difficult concepts.  Jessica also shares this quality.  It was truly a pleasure having her in our lab, and we wish her the best as she prepares to start the school year.

August 15, 2012 at 3:27 am Leave a comment

Excellent paper about stress fibers and focal adhesions from the lab of Margaret Gardel

Just a week ago, I presented a paper at our weekly literature review (journal club) which I found very interesting.  Many biophysics researchers are studying these complexes called focal adhesions.  Focal adhesions are complexes made of several different proteins that serve as the link between a cell’s actin cytoskeleton and the surrounding extracellular matrix (ECM).  It is thought that these complexes generate the tension necessary to pull a cell forward during migration.  Deficiencies in mechanotransduction of these complexes are implicated in numerous diseases, such as cardiomyopathies and cancer.

This paper, titled “Tension is required but not sufficient for focal adhesion maturation without a stress fiber template” is from the lab of Margaret Gardel at the University of Chicago.  The authors show that cellular tension and traction forces are still present even after disruption of the stress fiber template at adhesion sites.  The impaired stress fiber assembly also impeded focal adhesion compositional maturation and ECM remodeling.  Finally they showed that focal adhesion maturation can still proceed even when disrupting myosin II-dependent cellular tension up to 80%.  This study therefore argues against the current hypothesis that stress fibers induce focal adhesion maturation primarily by exerting myosin II-dependent tension at cell-ECM contacts.  Instead, they claim that the structure of the actin cytoskeleton serves to recruit multiple other proteins that are important to focal adhesion maturation.

What I found interesting about this study is that the authors were able to alter the structural framework of the actin cytoskeleton by disrupting only the radial stress fibers (perpendicular to the cell edge), while leaving the transverse arcs (parallel to the cell edge) unperturbed.

Here’s part of figure 1, which explains this.  Note the radial stress fibers in the wild type (WT) cells (indicated by the yellow arrows) and the transverse arcs (indicated by the red arrows), and then note the disappearance of the radial stress fibers in the subsequent images, all of which are ways to disrupt the radial stress fibers.  Also from the paxillin staining, we can see that the focal adhesions are unchanged (paxillin is a focal adhesion protein).

I find it very clever to change the architecture of the actin cytoskeleton, and then observe the changes in tension generation and focal adhesion maturation.  To be able to come up with this idea is a testament to a very creative group of researchers.

August 15, 2012 at 1:43 am Leave a comment

What do Green Fluorescent Protein, Black Pepper/Soap, and Magnetic Tweezers have in common?

A few months ago several members of the Dunn lab (Diego, Jack, and Armen) traveled to the Life Academy of Health and Biosciences in Oakland, CA to introduce high school students to the field of biophysics.  We thought it would be most useful to incorporate hands-on demonstrations and use visuals as a stepping stone to understand some of the more complicated concepts.  This event was organized with the help of Jessica Oya, who has worked in our lab over the past 2 summers as part of the IISME (Industry Initiatives for Science and Math Education) program at Stanford, and who invited us to teach her students about some things that we spend our days thinking of.

We set up 3 stations in her classroom.  1.) GFP- Green fluorescent protein.  In this station, Diego explained the concepts of fluorescence and protein structure, and used a vial of GFP under a black light to show how excitation/emission works.  He asked the students to come up with ideas how fluorescent proteins can be useful in biology to track motions of molecules, and was impressed with their creativity. 2.) Magnetic tweezers. In this station, Armen used magnetic beads and a microscope to explain concepts of magnetism and single-molecule biophysics.  By using an external magnet, the students were able to move the magnetic beads and align them in the direction of the magnetic field.  3.) Black pepper + soap in a dish.  In this station, Jack explained concepts of surface tension and hydrophobic vs. hydrophilic surfaces by placing black pepper in a dish of water, and then dropping some soap into the dish.  The visual effect is quite beautiful and serves as a wonderful way of teaching students about surface tension.

We truly enjoyed this experience, and hope that other schools in the greater Bay Area also partake in these programs.  Our plan is to scale up this event for the coming school year, and teach all the classrooms at this school.

August 10, 2012 at 9:16 pm Leave a comment

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