Difference between revisions of "User:GeorgeXu"

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# ''Xu G'', Umezawa M, Takeda K. ''Early Development Origins of Adult Disease Caused by Malnutrition and Environmental Chemical Sciences''. Journal of Health Science. 2008 Nov 10;55(1). [[doi:10.1248/jhs.55.11]]
# '''Xu G''', Umezawa M, Takeda K. 'Early Development Origins of Adult Disease Caused by Malnutrition and Environmental Chemical Sciences'. Journal of Health Science. 2008 Nov 10;55(1). [[doi:10.1248/jhs.55.11]]
# Wang HH, Isaacs FJ, Carr PA, Sun ZZ, ''Xu G'', Forest CR, and Church GM. Programming cells by multiplex genome engineering and accelerated evolution. Nature. in press
# Wang HH, Isaacs FJ, Carr PA, Sun ZZ, '''Xu G''', Forest CR, and Church GM. 'Programming cells by multiplex genome engineering and accelerated evolution'. Nature. in press

Revision as of 08:23, 11 July 2009

About Me

I am currently a Senior at Harvard College pursuing a combined A.B./S.M. degree in Biomedical Engineering and working in the Church Lab on a project utilizing lambda-red mediated recombineering [1] for genome engineering. My email is (georgexu AT fas.harvard.edu).

Research History

2005 Summer

I studied Berry Shrivel Disease under the mentorship of Professor Ken Shackel and Dr. Mark Krasnow at UC Davis's Department of Viticulture and Enology through the Young Scholar's Program. I imaged grape berry sections bathed in fluorescein diacetate, which is intracellularly hydrolyzed by viable cells to the fluorescent protein fluorescein [2], in order to assess cell viability in diseased grapes. Our hypothesis was that the disease was caused by massive cell death, in particular the companion cells surrounding the phloem. I had to leave for school before distinct symptoms presented and my data could be analyzed, but later analysis proved inconclusive. I can no longer find the CD with all of my 1000+ awesome images, but you can see a sample on slide 23 of Dr. Krasnow's presentation.

2007 Spring

During the second semester of my freshman year, I briefly worked part-time in the Weitz Lab with Dr. Amy Rowat on a microfluidics device for fluorescent detection, actuation, and control of individual yeast cells for directed evolution studies.

2007 Summer - 2007 Winter

During the summer following my freshman year I was a member of Harvard's 2007 iGEM team. The overall goal of our project was to have bacteria that would bind to a target and activate a signal, either through quorum sensing or transmembrane signal transduction. Our project consisted of three modules:

  1. We planned to utilize surface expression of a peptide library through fusion with the surface proteins Lpp-OmpA [3] and autodisplay protein AIDA-1 [4] for screening of binding sequences. We were able demonstrate successful fusion and targeting with his and strep2 tags but did not have time to test a random library.
  2. The project that I helped brainstorm was the quorum sensing. We utilized LuxI/LuxR quorum sensing found in V. fishcheri to create two systems: one was a single-cell that created both the "sender" LuxI molecule and the "receiver" luxR molecule, while the other had the "sender" and "receiver" constructs in separate cells. We successfully demonstrated quorum sensing in our system and began tests of combining these constructs with surface expression. My work on this project is (mostly) documented in my iGEM Lab Notebook.
  3. We planned to construct transmembrane signal transduction using the Fec system [5]. Unfortunately, the project turned out to be too ambitious and we were unsuccessful.

Professor George Church was one of the faculty advisors for this program and one of his students, Harris Wang, was one of the Teaching Fellows. After the iGEM jamboree, I began working for Harris in the Church lab.

2008 Summer

During the summer following my sophomore year I received generous funding from the Harvard Reischauer Institute's Summer Internship Program to work in Japan for 10 weeks. While there, I prepared and published a review article under the mentorship of Masakazu Umezawa and Professor Ken Takeda on the permanent health effects of adverse fetal environments [6].

2008 Spring - Present

I am currently working in the Church lab with Harris Wang and Dr. Farren Isaacs on lambda-red mediated recombineering [1]. Most of my work is on an internal lab wiki. Please contact me if you are interested.

Scientific Interests

Some day I will find time to write down the history of my scientific interests, starting from high school. Some day... Until then, I will just list my sources of inspiration.

  • Synthetic Biology: Creating tools for efficient manipulation of biological system and understanding biological systems well enough to engineer novel systems to within tight tolerances. Then someday, actually being able to rapidly engineer useful synethic biological organisms or systems. (iGEM and the Church Lab)
  • Systems Biology: Using the systems framework to find underlying biological principles that generalize to make sense of molecular biology diagrams... so that we can model and engineer them, of course. (A systems biology class at Harvard and Professor Uri Alon's book)
  • Biophysics: Understanding the physics behind biological processes... so that we can model and engineer them, natch. (a freshman seminar on molecular motors led by Professor Dudley Herschbach and Berg and Purcell's Physics of Chemoreception [7])
  • Medical Devices: Low-cost diagnostics, especially lab on a chip devices, and non-invasive health monitoring devices.


  1. Xu G, Umezawa M, Takeda K. 'Early Development Origins of Adult Disease Caused by Malnutrition and Environmental Chemical Sciences'. Journal of Health Science. 2008 Nov 10;55(1). doi:10.1248/jhs.55.11
  2. Wang HH, Isaacs FJ, Carr PA, Sun ZZ, Xu G, Forest CR, and Church GM. 'Programming cells by multiplex genome engineering and accelerated evolution'. Nature. in press


This section is under construction until I have something that I can write up. In the meantime, please read my notes on reading done as an Undergraduate Senior.

Other Interests

Roughly Chronologically:

Magic: the Gathering

I started playing "school-yard MtG" with manadrop and rocks to keep cards from blowing away in 4th grade (Ice Age block) and continued until the Invasion block (8th grade). I still browse Daily Magic to see the new deck tech and occasionally draft (either NetDraft or some FNM equivalent).


I have been playing on-and-off since 1988. I used to play Terran in Fastest/BGH vs the AI, but in 2006 I switched to Protoss. I still visit Teamliquid occasionally. My main builds are:

I am a terrible player because I don't practice much (I have yet to break 120 APM or D on ICCUP).


I enjoyed playing basketball in elementary school, but I was diagnosed with Osgood-Schlatter disease in sixth grade. It was causing me knee pain when I did impact intensive sports so I switched to swimming in middle school. In my prime (league finals of Junior year in High School), I could swim 1:00 low for 100YD FLY and 54 high for 100YD FR. Not amazing, but given that I'm pretty short and have small feet, I'm pretty proud of those times :). I doubt I can get anywhere near those times nowadays.

Amateur Astronomy

I did some amateur observing with RFu in my Junior year of High School. I continued dabbling in amateur astronomy and ended up being Treasurer for the astronomy club at Harvard. I currently only own a dinky set of binoculars, but if I end up in a place that has clear skies often (California) I am strongly considering getting a nice 10in Dobsonian and finally learning the sky well.


I started learning from youtube videos and random internet articles during my last semester of High School. Seeing how obsessed I was with guitar, my parents bought me a Taylor Big Baby as a graduation present. I have yet to name her ;).


  1. Thomason L, Court DL, Bubunenko M, Costantino N, Wilson H, Datta S, and Oppenheim A. Recombineering: genetic engineering in bacteria using homologous recombination. Curr Protoc Mol Biol. 2007 Apr;Chapter 1:Unit 1.16. DOI:10.1002/0471142727.mb0116s78 | PubMed ID:18265390 | HubMed [lambdared]
  2. Heslop-Harrison J and Heslop-Harrison Y. Evaluation of pollen viability by enzymatically induced fluorescence; intracellular hydrolysis of fluorescein diacetate. Stain Technol. 1970 May;45(3):115-20. PubMed ID:4192549 | HubMed [FDA]
  3. Earhart CF. Use of an Lpp-OmpA fusion vehicle for bacterial surface display. Methods Enzymol. 2000;326:506-16. PubMed ID:11036660 | HubMed [LppOmpA]
  4. Maurer J, Jose J, and Meyer TF. Autodisplay: one-component system for efficient surface display and release of soluble recombinant proteins from Escherichia coli. J Bacteriol. 1997 Feb;179(3):794-804. PubMed ID:9006035 | HubMed [AIDA1]
  5. Koebnik R, Locher KP, and Van Gelder P. Structure and function of bacterial outer membrane proteins: barrels in a nutshell. Mol Microbiol. 2000 Jul;37(2):239-53. PubMed ID:10931321 | HubMed [Fec]
  6. Xu G, Umezawa M, Takeda K. Early Development Origins of Adult Disease Caused by Malnutrition and Environmental Chemical Sciences. Journal of Health Science. 2008 Nov 10;55(1). doi:10.1248/jhs.55.11

  7. Berg HC and Purcell EM. Physics of chemoreception. Biophys J. 1977 Nov;20(2):193-219. DOI:10.1016/S0006-3495(77)85544-6 | PubMed ID:911982 | HubMed [chemotaxis]

All Medline abstracts: PubMed | HubMed