Monday, January 14, 2008
Synthetic Biology
the four challenges that greatly limit engineering biology today are 1)biological complexity; 2)the tedious and unreliable construction and characterization of synthetic biological systems; 3)the spontaneous variation of biological systems; and 4) evolution.
Lessons from the past
standardization
Registry of Standard Biological Parts: http://parts.mit.edu/registry/index.php/Main_Page
decoupling;
separation of deign and implementation
for example, one group design useful DNA sequences and another group synthesize the piece of DNA chemically. (it seems possible now)
abstraction
design of reproducing machines
reliable computing with unreliable components
error detection & correction mechanism
self-replicating automata
additional reading:
Elowitz, M. B. & Leibler, S. A synthetic oscillatory network of transcriptional
regulators. Nature 403, 335–-338 (2000)
Sprinzak, D. & Elowitz, M. B. Reconstruction of genetic circuits. Nature
doi:10.1038/nature04335
Sunday, November 25, 2007
How to read and write NTFS partition in Mac OS X 10.5 Leopard
1. Download and install MacFUSE for Mac OS X 10.5This approach work on my Mac OS X 10.5 + 10.5.1 updates and Windows XP SP2 with NTFS partition on MacBook Pro (Model Identifier MacBookPro3,1).
2. Download and install NTFS-3g for Mac OS
3. Restart! If you are lucky you can try read and write your Windows' NTFS partition now.
Before you decide to proceed, google "read write NTFS Mac OS X leopard" to be informed of newest advancement and check for latest versions of MacFUSE and NTFS-3g.
Reference
1. MacFUSE http://code.google.com/p/macfuse/
2. NTFS-3g http://www.ntfs-3g.org/
3. NTFS-3g for Mac OS http://macntfs-3g.blogspot.com/
4. Filesystem in Userspace http://en.wikipedia.org/wiki/Filesystem_in_Userspace
5. Filesystem in Userspace http://fuse.sourceforge.net/wiki/index.php/FileSystems
6. NTFS on your Mac http://www.tuaw.com/2007/11/19/ntfs-on-your-mac-two-ways/
Monday, March 12, 2007
Modeling Biomedical Networks
If the rate of change of all variables (concentrations of matters) are constant we get a steady state. If Additionally all reactions fluxes are zero, we have an equilibrium.
Calculating steady state
There are several numerical methods to calculate steady state, such as improved Newton method, forward integration and backward integration. However none of them are perfect even to find a steady state in complex systems, which may have several steady states.
Metabolic Control Analysis
MCA describes how the systems reacts to changes of parameters. Elasticities describes how the reaction rates depend on the metabolite concentrations. Control coefficients describes how the systems behavior depend on the reaction rates
References:
http://projects.eml.org/downloads/copasi/CopasiTutorial.pdf
Wednesday, March 07, 2007
Install Matlab R2006b
SimBiology extends MATLAB with tools for modeling, simulating, and analyzing biochemical pathways. You can create your own block diagram model using predefined blocks. You can manually enter in species, parameters, reactions, rules, kinetic laws, and units, or read in Systems Biology Mark-Up Language (SBML) models. SimBiology lets you simulate a model using stochastic or deterministic solvers and analyze your pathway with tools such as parameter estimation and sensitivity analysis.First get the following MATLAB ISO images at ftp://pxe/software/Matlab2006b (perhaps only available for LAN of USTC)
mount these images and enter the directory where you want to install matlab, create a matlab directory ($MATLAB).
run CD1/install. The graphic interface is easy to complete.
When I finished the normal install and tried to run matlab. It poped a very lengthy error message java.lang.ExceptionInInitializerError at com.mathworks.mde.filebrowser.FileBrowser.
and collapsed thereafter. But if I run matlab -nojvm, it worked normally.
Solution: the java compiler that comes together with MATLAB caused the above error. Replace it with my own version of java (jre1.5.0_06)
cd $MATLAB/sys/javaAnd then MATLAB works now. Bingo!
mv java java-backup
ln -s path_of_your_own_java java
PS: kkk recommended another standalone software, Copasi, to build and simulate biomedical networks. Have a look at it.
COPASI is a software application for simulation and analysis of biochemical networks. COPASI — a COmplex PAthway SImulator. Bioinformatics 22, 3067-74.
Current Features:
- Stochastic and deterministic time course simulation
- Steady state analysis (including stability)
- Metabolic control analysis / sensitivity analysis
- Elementary mode analysis
- Mass conservation analysis
- Calculation of Lyapunov exponents
- Parameter scans
- Optimization of arbitrary objective functions
- Parameter estimation using data from time course and/or steady state experiments
- Sliders for interactive parameter changes
- Global parameter to change multiple kinetic rates at once
- Imports and exports SBML (export only in level 2 version 1, import all levels)
- Loads Gepasi files
- Export in Berkeley Madonna format and C source code of the ODE system generated from the chemical reactions
- Versions for MS Windows, Linux, OS X, and Solaris SPARC
- Command line version for batch processing
- Visit this page often, new releases will contain many more features!
Still No Sense of Signaling Network Research
After I realized the above idea, I decided to read systematically publications in this area. Today I am reading the Science STKE Signaling Breakthroughs of the Year. And now another list of paper to be read (The number of papers in this list is increasing expotentially, I don't know when can I have my sense of them)
[1]G. Altan-Bonnet, R. N. Germain, Modeling T cell antigen discrimination based on feedback control of digital ERK responses. PLoS Biol. 3, e356 (2005).[CrossRef][Medline]
[2]J. R. Pomerening, S. Y. Kim, J. E. Ferrell, Jr., Systems-level dissection of the cell-cycle oscillator: Bypassing positive feedback produces damped oscillations. Cell 122, 565–578 (2005).[CrossRef][Medline]
[3]O. Brandman, J. E. Ferrell, Jr., R. Li, T. Meyer, Interlinked fast and slow positive feedback loops drive reliable cell decisions. Science 310, 496–498 (2005).[Abstract/Free Full Text]
Friday, March 02, 2007
Paper Analysis -2007-03-02
A NETWORK RECONSTRUCTION includes a chemically accurate representation of all of the biochemical events that are occurring within a defined signalling network, and incorporates the interconnectivity and functional relationships that are inferred from experimental data.This article give a enlightening theoretical analysis of signal transduction networks: the order of magnitude of numbers of network components (receptor, kinase, phophatase), the order of magnitude of interconnectivity(~2.5 degree of interconnectivity per component). We can use Combinatorial Complexity to characterize this idea. The catalog of network components without post-translational modification can be inferred from the results the genome annotation. The spectrom of network components after PTM and protein-protein interaction during varies states of the network is expected to be assayed with future proteomic experimental techniques (though I feel passive with expectation). But what use or what consequences of these large potential spectrum of various network components means?
The following paper it refers may be worth reading.
[1]
Papin, J. A. & Palsson, B. O. The JAK–STAT signaling network in the human B-cell: an extreme signaling pathway analysis. Biophys. J. 87, 37–46 (2004).
[2]
Resat, H., Wiley, H. S. & Dixon, D. A. Probability-weighted dynamic Monte Carlo method for reaction kinetics simulations. J. Phys. Chem. B 105, 11026–11034 (2001)
[3]
Bhalla, U. S. & Iyengar, R. Emergent properties of networks of biological signaling pathways. Science 283, 381–387 (1999).
Describes some of the first large-scale analyses of signalling reactions.
[4]
Hoffmann, A., Levchenko, A., Scott, M. L. & Baltimore, D. The IkappaB–NF-kappaB signaling module: temporal control and selective gene activation. Science 298, 1241–1245 (2002).
Shows the powerful integration of mathematical modelling with experimental investigation
[5]
Lee, E., Salic, A., Kruger, R., Heinrich, R. & Kirschner, M. W. The roles of APC and Axin derived from experimental and theoretical analysis of the Wnt pathway. PLoS Biol. 1, 116–132 (2003).
[6]
Prill, R., Iglesias, P.A. and Levchenko, A. Dynamic Properties of Small Regulatory Motifs Contribute to Biological Network Organization. PLoS Biology 3(11): e343 (2005)
[7]
Sivakumaran, S., Hariharaputran, S., Mishra, J. & Bhalla, U. S. The database of quantitative cellular signaling: management and analysis of chemical kinetic models of signaling networks. Bioinformatics 19, 408–415 (2003)
Thursday, March 01, 2007
Omics is Just a Startup
Now besides proteomics and genomics, here comes the metabolomics, with similar promising declarations. As the lates Nature essay (Meet the human metabolome)states,
Metabolomics is the study of the raw materials and products of the body's biochemical reactions, molecules that are smaller than most proteins, DNA and other macromolecules. The aim is to be able to take urine, blood or some other body fluid, scan it in a machine and find a profile of tens or hundreds of chemicals that can predict whether an individual is on the road to a disease, say, or likely to experience side-effects from a particular drug.In fact, researchers in metabolomics are even more optimistic, declaring that
Small changes in the activity of a gene or protein (which may have an unknown impact on the workings of a cell) often create a much larger change in metabolite levels particular concentrations and combinations can reveal something about drugs or diseaseHowever, I am suspecious about their promise. First, considering the great diversity of metabolites in human fluids, we still have not a powerful enough assay to identify the all metabolite in a high-throughout manner and measure their concentrations. Second, the changes in the metabolome is more susceptible to enviromental factors, thus it will be difficult to tell significant changes related to human diseases from temporal fluctuations.
Anyway, let be a little optimistic, omics is just a startup!
Monday, February 05, 2007
Owe Ohler
Ohler U, Shomron N, Burge CB (2005) Recognition of Unknown Conserved Alternatively Spliced Exons. PLoS Comput Biol 1(2): e15 doi:10.1371/journal.pcbi.0010015
Ohler has scientific collaboration with Christopher B. Burge, from MIT, probably a BIG guy in this area. Pay attention to him.
What use is the identification of alternative splicing sites of. The author says that "The identification of such variants has until recently relied solely on the sequencing and comparison of expressed sequence tags (ESTs), but the number of available ESTs is not large enough to cover all variants under all conditions" According a Nature Genetics Review, which I reviewed in last post, the development of microarray platform for finding unknown exons are on the way. Probably, even a microarray experiment can not still covers all variants under all conditions. Thus a preliminary computational prediction gives many possible alternative splicing sites, among which many may be false positive, which can be tested by a microarray experiment. Such prediction may also help the design of the array.
Method: pair hidden Markov model
Patterns of flanking sequence conservation and a characteristic upstream motif for microRNA gene identification RNA (2004), 10:1309-1322
Quantification of transcription factor expression from Arabidopsis images Bioinformatics 2006 22(14):e323-e331; doi:10.1093/bioinformatics/btl228In spite of the great success of microarray technique in gene expression profiling, it fails to detect spatial features of gene expression, thus the confocal microscopy can also provide quantitative information of gene expression with greater spatial and temporal resolution. This paper describes a software protocol of analyzing confocal microscopy images. (How the high-throughput is achieved?)
imagine registration
GFP transcriptional fusion GFP serves as marker of mRNA expression level
GFP translational fusion
Monday, January 29, 2007
Paper Analysis: Microarray technology: beyond transcript profiling and genotype analysis
Nature Reviews Genetics 7, 200-210 (March 2006) | doi:10.1038/nrg1809
I have spent nearly three days reading this review on microarray. It is partly because this paper involves too many new concepts for me to digest, partly because, I have to admit, I have wasted too much time on BBS, films and music ^_^. Even until now I still cannot declare to absorb all materials in this paper, but i think it is better to take some notes here for it may urge me to concentrate on research.
This paper describe the following microarray development
Process | Status* |
---|---|
*From most to least developed: mature, in progress, under development, early stages, pilot phase, idea. CGH, comparative genomic hybridization; ChIP-on-chip, on-chip chromatin immunoprecipitation. | |
Transcriptional profiling | Mature, but still to be improved |
Genotyping | Mature, but still to be improved |
Splice-variant analysis | In progress |
Identification of unknown exons | Early stages |
DNA-structure analysis | Pilot phase |
ChIP-on-chip | In progress |
Protein binding | Under development |
Protein–RNA interaction | Idea |
Chip-based CGH | In progress |
Epigenetic studies | Under development |
DNA mapping | Mature |
Resequencing | In progress |
Large-scale sequencing | Under development |
Gene/genome synthesis | Early stages |
RNA/RNAi synthesis | Pilot phase |
Protein–DNA interaction | Under development |
On-chip translation | Under development |
Universal microarray | Under development |
He thoughts transcriptional profiling is relative in technique but the data analysis and interpretation. Some organization are take effect in this path, such as Microarray Gene Expression Data (MGED) Society, Gene Ontology Consortium and Bioconductor.
Expanding RNA studies the transcried RNA profile is a mixture of pre-mRNA, various form of alternative spliced mature mRNA, non-coding RNA and regualatory RNA. If we think about the effect of alternative splicing, it is possible that we may ignorant other forms and exons in the genome sequence which is not seen in our experiement samples. Then how to know other exons and what condition they are retained in mature mRNA, we can built an array consisting of oligonucleotide representing all known exons from genome annotation analysis. This array can then be used for the above condition.
Another question arising is that how can we find exons that escape the notice of genome annotation analysis. "One option is to synthesize oligonucleotides that correspond to the sequences at the exon–intron boundaries with their 5' ends attached to the chip surface "
Another approach is the entire genome microarray (tiling path), but the fragment is rather long which may miss some active sites of interest.
ChIP-on-chip on-chip chromatin immunoprecipitation. But, how this technique get high throughput if only one kind of protein can be precipitated due to the specificity of antibody binding? Needs more reading to understand this technique.
The author also predicted that " all analyses that are carried out with DNA are feasible at the level of RNA also."
comparative genomic hybridization (CGH), a method that is used to analyse variations in DNA copy number
The following part of this paper describes on demand sythesis based on microfluidic microarray, such as probe production (parallel production of large amount of different of oligomers), gene synthesis, RNAi production and protein in situ synthesis. Finally he introduced universal microarray platform based on L-DNA with great enthusiasm.
Conclusions:
1. To some extent, microarray technique means a new data-driven method e.g placing data production before intellectual concepts. This method is different from traditional hypothesis driven research in biology but is successful in physics.
2. The global view obtained by microarray approaches might lead researchers to appreciate more complexity of biological systems.
3. Experimental multiplexing by analysing different processes on a single system platform will become important. The in vitro systems biology will emerge competing (or complementing) in silico systems biology.
Here is a list of notable research project about microarray analysis http://filtr.blogspot.com/2007/02/research-projects-on-microarray.html
Monday, January 22, 2007
Xianghong Zhou's Papers
1. Gene Aging Nexus: A Web Database and Data Mining Platform for Microarray Data on Aging
keywords:
meta-analysis: by first extracting expression patterns form individual microarray datasets and then identifying recurrent signals, these approaches may enhance signal-noise separation.
differential expression analysis:
co-expression analysis: Zhou proposed a new method to mine regulatory modules in previous papers Mining dense subgraphs across massive biological networks for functional discovery.
no major biological breakthrough.
2. Integrative missing value estimation for microarray data
Question Answered:
Due to the inherent noise and the limitation of experimental systems, a microarray dataset on average has more than 5% missing values, affecting more than 60% of the genes. Such missing values made some subsequent analysis methods inapplicable or greatly decrease their performance. Thus the question of missing value estimation.
Basic Idea:
How to choose neighboring genes when not enough information is available in internal microarray dataset. Intuitively, if a set of genes frequently show expression similarity to the target gene over multiple data sets, they constitute a robust neighborhood which tend to show expression co-variations with the target gene.
other concepts:
LLS Local Least Square
Bayesian principle component analysis
singular value decomposition
support vector machines
Tuesday, December 05, 2006
BioMed Search
BioMed Search has been created by Alex Ksikes, a PhD student in University of Cambridge. The goal of BioMed search is to organize figures, images or schema found in biomedical articles. Over 1 Million images have been indexed and more is on its way. BioMed Seach indexes image captions along with the citations to these images.
A sample search with the keyword insulin returns the following result
The Journal of biological chemistry.
It is the well formated scientific literatures that makes the such search possible. Pay attention and try to improve it.
BioMed Search
BioMed Search has been created by Alex Ksikes, a PhD student in University of Cambridge. The goal of BioMed search is to organize figures, images or schema found in biomedical articles. Over 1 Million images have been indexed and more is on its way. BioMed Seach indexes image captions along with the citations to these images.
A sample search with the keyword insulin returns the following result
Insulin resistance is mediated by a proteolytic fragment of the insulin receptor.
It is the well formated scientific literatures that makes the such search possible. Pay attention and try to improve it.
My Brain
Thanks for Wu Xiang@Cognitive Neuroscience Labratory of USTC
I am amazed to see my brain. Following a silent noise background, my brain appears as a light dot. It become larger and larger, like an approaching distant UFO. Next, my cortex come into sight, however, at first, it looks like an embyro in uterus. It is unset. ( I forgot what I am thinking then). At last, it comes into shape, and shrink, and disappear in the deep noise background again.
Saturday, December 02, 2006
Working with Emacs Muse
I have been trying to use emacs muse for the whole afternoon, bacause the frequent breakdown of Google Pages really annoyed me and its low efficiency is unbearable.
I know it is time for me to leave those unstable WYSIYG applications aside and find a stabel and fast solution to maintain my personal homepage. The simplicity and grace of EmacsWiki once catched my eye. After steps of googling, I learned that Emacs Muse has substitute Emacs Wiki as its decendent. Emacs muse is rather easy and enable the full features of Emacs, and it can also output pdf format, maybe I can use it to write reports in the future.
Some Notes:
- the defaut key for footnote is rather long, it is better to reset it use global-set-key
- The CSS templates of EmacsWiki can be used for Muse with less changes. Here is a article about the use of Muse
Wednesday, November 29, 2006
NIC Disabled
How to check if your Network Card is Enabled or Disabled
Right Click on My Computer
Select Properties
Select the Hardware Tab
Click on the Device Manager button and double click on Network Adapters
The Red Cross shows means the Network Card is Disabled.
The one with no Cross means the Network card is enabled.
How To Enable the Disabled Card ?
Right Click on the network card that is disabled and and Click on Enable
Friday, November 24, 2006
Does Indetificatin of Transcriptional Network Take Alternative Splicing Into Accout?
Saturday, November 11, 2006
Why Europeanian discovered theory of continental drift?
Sunday, November 05, 2006
Systems Biology Review Series
Following the striking opening line comes a sound argument: organism is heterogenous and biological process is dynamic; thus, systems biology require dynamic, spatially resolved data on gene and protein function; This type of data is complex, thus data must be collected with reference to specific, quantitative models.
The authors say practical trade-offs must be considered when selecting what to measure and how frequently to measure it. I wonder whether we can build a model to model the experimental process instead of a preliminary experiment, or at least the experiment model give some insight into the process before the indispensable preliminary experiment.
About the third point data fusion, no single method is sufficient to measure the full diversity of protein signals. On the other hand, even there really exist a general method, how can we believe it gives the right data, given the inaccuracy of biological experiment. Therefore, data fusion also means error detection.
About mass spectrometry, the biggest limitation is not the instrumentation, but rather inadequate software and the need to confirm peptide assignments by hand. Further reading needed to confirm whether it is a rich land.
Computed metrics: In the paper analysis of cellular biology, I made a analog that the change of magnetic field incites electronic field, we biologist have long focus on the absolute level of protein or gene, but the change may make difference, however we have no a method to characterize the change until now. The section express similar idea.
Friday, October 27, 2006
Alterbative Splicing--Christopher Lee, Jacek Majewski
Professor Lee : http://www.uclaaccess.ucla.edu/UCLAACCESS/Web/Faculty.aspx?ri=434
Professor J. Majewski: http://genomequebec.mcgill.ca/majewski/
Need a review of their method and focus.
Professor Black, Doug also engage research in alternative splicing, from a more traditional chemical and biological perspective
Sunday, October 22, 2006
Bioinformatics -- Andy Baxevanis Ouellette BFF
Baxevanis's previous work focus on computation analyis of disease-causing mutations from a structural standpoint, using innovative approaches to deduce the prisece structure change in protein cause by a specific genetic mutation. (What method?)
During the early development of microarray, Baxevanis's group developed the first publicly available program to restore and analyze microarray data.
Now, Baxevanis's group the group developed a software program known as GeneLink, which enables researchers to analyze large data sets from studies of complex-trait genetic disorders, such as cancer, diabetes, and hypertension, which involve many genes along with environmental factors.
Quelette is the head of UBC Bioinformatics Centre (UBiC) and this graduate program is worth of time to have a look.