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Towards in situ Single Cell Systems Biology


Lubeck, Eric (2016) Towards in situ Single Cell Systems Biology. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9BK1999.


Systems-level studies of biological systems rely on observations taken at a resolution lower than the essential unit of biology, the cell. Recent technical advances in DNA sequencing have enabled measurements of the transcriptomes in single cells excised from their environment, but it remains a daunting technical problem to reconstruct in situ gene expression patterns from sequencing data. In this thesis I develop methods for the routine, quantitative in situ measurement of gene expression using fluorescence microscopy.

The number of molecular species that can be measured simultaneously by fluorescence microscopy is limited by the pallet of spectrally distinct fluorophores. Thus, fluorescence microscopy is traditionally limited to the simultaneous measurement of only five labeled biomolecules at a time. The two methods described in this thesis, super-resolution barcoding and temporal barcoding, represent strategies for overcoming this limitation to monitor expression of many genes in a single cell. Super-resolution barcoding employs optical super-resolution microscopy (SRM) and combinatorial labeling via-smFISH (single molecule fluorescence in situ hybridization) to uniquely label individual mRNA species with distinct barcodes resolvable at nanometer resolution. This method dramatically increases the optical space in a cell, allowing a large numbers of barcodes to be visualized simultaneously. As a proof of principle this technology was used to study the S. cerevisiae calcium stress response. The second method, sequential barcoding, reads out a temporal barcode through multiple rounds of oligonucleotide hybridization to the same mRNA. The multiplexing capacity of sequential barcoding increases exponentially with the number of rounds of hybridization, allowing over a hundred genes to be profiled in only a few rounds of hybridization.

The utility of sequential barcoding was further demonstrated by adapting this method to study gene expression in mammalian tissues. Mammalian tissues suffer both from a large amount of auto-fluorescence and light scattering, making detection of smFISH probes on mRNA difficult. An amplified single molecule detection technology, smHCR (single molecule hairpin chain reaction), was developed to allow for the quantification of mRNA in tissue. This technology is demonstrated in combination with light sheet microscopy and background reducing tissue clearing technology, enabling whole-organ sequential barcoding to monitor in situ gene expression directly in intact mammalian tissue.

The methods presented in this thesis, specifically sequential barcoding and smHCR, enable multiplexed transcriptional observations in any tissue of interest. These technologies will serve as a general platform for future transcriptomic studies of complex tissues.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Systems Biology; Biophysics; Single Molecule Microscopy; Gene Expression
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Biochemistry and Molecular Biophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Cai, Long
Thesis Committee:
  • Sternberg, Paul W. (chair)
  • Elowitz, Michael B.
  • Gradinaru, Viviana
  • Cai, Long
Defense Date:20 November 2015
Record Number:CaltechTHESIS:02262016-115004310
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 2 adapted for ch. 3 adapted for ch. 4
Lubeck, Eric0000-0002-5457-0258
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9589
Deposited By: Eric Lubeck
Deposited On:10 May 2016 19:41
Last Modified:06 Nov 2019 17:11

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