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% This file was created with JabRef 2.6.
% Encoding: Cp1252
@BOOK{Barabasi2002,
title = {Linked: The New Science of Networks},
publisher = {Perseus Books Group},
year = {2002},
author = {Albert-L\'{a}szl\'{o} Barab\'{a}si},
pages = {256},
edition = {First},
month = may,
isbn = {0738206679},
owner = {jfreyre},
timestamp = {2008.07.09}
}
@ARTICLE{Freyre-Gonzalez2008,
author = {Julio Augusto Freyre-Gonz\'{a}lez and Jos\'{e} Antonio Alonso-Pav\'{o}n
and Luis Gerardo Treviño-Quintanilla and Julio Collado-Vides},
title = {Functional architecture of \textit{Escherichia coli}: new insights
provided by a natural decomposition approach.},
journal = {Genome Biol},
year = {2008},
volume = {9},
pages = {R154},
number = {10},
month = {Oct},
abstract = {ABSTRACT: BACKGROUND: Previous studies have used different methods
in an effort to extract the modular organization of transcriptional
regulatory networks. However, these approaches are not natural, as
they try to cluster strongly connected genes into a module or locate
known pleiotropic transcription factors in lower hierarchical layers.
Here, we unravel the transcriptional regulatory network of Escherichia
coli by separating it into its key elements, thus revealing its natural
organization. We also present a mathematical criterion, based on
the topological features of the transcriptional regulatory network,
to classify the network elements into one of two possible classes:
hierarchical or modular genes. RESULTS: We found that modular genes
are clustered into physiologically correlated groups validated by
a statistical analysis of the enrichment of the functional classes.
Hierarchical genes encode transcription factors responsible for coordinating
module responses based on general interest signals. Hierarchical
elements correlate highly with the previously studied global regulators,
suggesting that this could be the first mathematical method to identify
global regulators. We identified a new element in transcriptional
regulatory networks never described before: intermodular genes. These
are structural genes which integrate, at the promoter level, signals
coming from different modules, and therefore from different physiological
responses. Using the concept of pleiotropy, we have reconstructed
the hierarchy of the network and discuss the role of feedforward
motifs in shaping the hierarchical backbone of the transcriptional
regulatory network. CONCLUSIONS: This study sheds new light on the
design principles underpinning the organization of transcriptional
regulatory networks, showing a novel nonpyramidal architecture comprised
of independent modules globally governed by hierarchical transcription
factors, whose responses are integrated by intermodular genes.},
doi = {10.1186/gb-2008-9-10-r154},
owner = {jfreyre},
pii = {gb-2008-9-10-r154},
pmid = {18954463},
timestamp = {2008.10.29},
url = {http://dx.doi.org/10.1186/gb-2008-9-10-r154}
}
@MISC{Freyre-Gonzalez2005,
author = {Julio A. Freyre-Gonz\'{a}lez and Jos\'{e} A. Alonso-Pav\'{o}n and
Daniel V\'{a}zquez-Hernandez and Mario Sandoval-Calderon and Mariana
Matus-Garc\'{\i}a and Ortega-del Vecchyo, Diego and Julio Collado-Vides},
title = {Modular and hierarchical organization of the transcriptional regulatory
network of \textit{Escherichia coli} K-12},
howpublished = {5th International Workshop on Bioinformatics and Systems Biology,
Poster Session, Berlín, Alemania},
month = {August},
year = {2005},
abstract = {There are strong arguments that support the idea of modular organization
in the cell [3]. A module is defined as a group of correlated elements
that cooperate in a specific cellular function [3,1]. In genetic
networks, these modules are integrated by transcription factors (TFs)
and genes that act coordinately when specific stimuli are present.
In biological networks there exist global TFs that interact with
several elements of many modules. This makes difficult or impossible
to classify those TFs into a single module. Consequently, we may
classify the network’s elements into two groups: elements that belong
to modules (genes and local TFs, which will hereafter be called modular
elements), and elements that coordinate such modules in a hierarchical
fashion (global TFs and sigma factors, which will hereafter be called
control elements). This suggests that a methodology that will allow
for the classification of the network’s genes in one of the aforementioned
groups is required.
Recently, topological analyses have suggested the existence of hierarchical
modularity in the transcriptional regulatory network (TRN) of E.
coli [2,6,5]. Nevertheless, these studies have neglected the importance
of classifying genes in modular and control elements, as well as
the existence of feedback circuits among them. Such feedback circuits
could be interpreted as a mechanism by which control elements retrieve
information about the status of genes in modules and, based on this
feedback signal, generate decisions about the fate of the cell.
Assuming these hypotheses, in our laboratory, we are working on an
algorithm to propose a hierarchical structure of the TRN:
1. Using data from RegulonDB [7,4] we will decompose the network,
through the analysis of the node degree and clustering coefficient
distribution, into the aforementioned groups and temporally remove
the control elements.
2. Using Monica Riley’s gene functional assignations [8] we will analyze
the modules to determine whether they are physiologically correlated
or not.
3. Finally, we will add the removed control elements to infer the
hierarchical structure of the TRN.
On this poster we will show the results obtained from applying this
methodology to the TRN of E. coli.},
owner = {jfreyre},
timestamp = {2008.11.09}
}
@ARTICLE{Gottesman1984,
author = {S. Gottesman},
title = {Bacterial regulation: global regulatory networks},
journal = {Annu Rev Genet},
year = {1984},
volume = {18},
pages = {415--441},
doi = {10.1146/annurev.ge.18.120184.002215},
keywords = {Aerobiosis; Anaerobiosis; Bacterial Proteins; Base Sequence; Cyclic
AMP; DNA Repair; Energy Metabolism; \textit{Escherichia coli}; Gene
Expression Regulation; Glucose; Heat-Shock Proteins; Nitrogen; Operon;
Phosphate; Receptors, Cyclic AMP; Repressor Proteins; s},
owner = {jfreyre},
pmid = {6099091},
timestamp = {2008.02.05},
url = {http://dx.doi.org/10.1146/annurev.ge.18.120184.002215}
}
@ARTICLE{Griffith2002,
author = {Kevin L Griffith and Ishita M Shah and Todd E Myers and Michael C
O'Neill and Richard E Wolf},
title = {Evidence for ``pre-recruitment'' as a new mechanism of transcription
activation in \textit{Escherichia coli}: the large excess of SoxS
binding sites per cell relative to the number of SoxS molecules per
cell},
journal = {Biochem Biophys Res Commun},
year = {2002},
volume = {291},
pages = {979--986},
number = {4},
month = {Mar},
abstract = {In response to the oxidative stress imposed by redox-cycling compounds
like paraquat, \textit{Escherichia coli} induces the synthesis of
SoxS, which then activates the transcription of approximately 100
genes. The DNA binding site for SoxS-dependent transcription activation,
the "soxbox," is highly degenerate, suggesting that the genome contains
a large number of SoxS binding sites. To estimate the number of soxboxes
in the cell, we searched the \textit{E. coli} genome for SoxS binding
sites using as query sequence the previously determined optimal SoxS
binding sequence. We found approximately 12,500 sequences that match
the optimal binding sequence under the conditions of our search;
this agrees with our previous estimate, based on information theory,
that a random sequence the size of the \textit{E. coli} genome contains
approximately 13,000 soxboxes. Thus, fast-growing cells with 4-6
genomes per cell have approximately 65,000 soxboxes. This large number
of potential SoxS binding sites per cell raises the interesting question
of how SoxS distinguishes between the functional soxboxes located
within the promoters of target genes and the plethora of equivalent
but nonfunctional binding sites scattered throughout the chromosome.
To address this question, we treated cells with paraquat and used
Western blot analysis to determine the kinetics of SoxS accumulation
per cell; we also determined the kinetics of SoxS-activated gene
expression. The abundance of SoxS reached a maximum of 2,500 molecules
per cell 20 min after induction and gradually declined to approximately
500 molecules per cell over the next 1.5 h. Given that activation
of target gene expression began almost immediately and given the
large disparity between the number of SoxS molecules per cell, 2,500,
and the number of SoxS binding sites per cell, 65,000, we infer that
SoxS is not likely to activate transcription by the usual "recruitment"
pathway, as this mechanism would require a number of SoxS molecules
similar to the number of soxboxes. Instead, we propose that SoxS
first interacts in solution with RNA polymerase and then the binary
complex scans the chromosome for promoters that contain a soxbox
properly positioned and oriented for transcription activation. We
name this new pathway "pre-recruitment."},
doi = {10.1006/bbrc.2002.6559},
institution = {Department of Biological Sciences, University of Maryland Baltimore
County, Baltimore, Maryland 21250, USA.},
keywords = {Bacterial Proteins; Binding Sites; Blotting, Western; Cell Division;
DNA-Binding Proteins; \textit{Escherichia coli}; \textit{Escherichia
coli} Proteins; Gene Expression Regulation, Bacterial; Genome, Bacterial;
Kinetics; Numerical Analysis, Computer-Assisted; Oxidative Stress;
Paraquat; Protein Transport; Trans-Activation (Genetics); Trans-Activators;
Transcription Factors},
owner = {jfreyre},
pii = {S0006291X02965599},
pmid = {11866462},
timestamp = {2008.02.05},
url = {http://dx.doi.org/10.1006/bbrc.2002.6559}
}
@ARTICLE{Hartwell1999,
author = {L. H. Hartwell and J. J. Hopfield and S. Leibler and A. W. Murray},
title = {From molecular to modular cell biology},
journal = {Nature},
year = {1999},
volume = {402},
pages = {C47--C52},
number = {6761 Suppl},
month = {Dec},
abstract = {Cellular functions, such as signal transmission, are carried out by
'modules' made up of many species of interacting molecules. Understanding
how modules work has depended on combining phenomenological analysis
with molecular studies. General principles that govern the structure
and behaviour of modules may be discovered with help from synthetic
sciences such as engineering and computer science, from stronger
interactions between experiment and theory in cell biology, and from
an appreciation of evolutionary constraints.},
doi = {10.1038/35011540},
institution = {Fred Hutchinson Cancer Center, Seattle, Washington 98109, USA.},
keywords = {Action Potentials; Evolution; Forecasting; Models, Biological; Molecular
Biology},
owner = {jfreyre},
pmid = {10591225},
timestamp = {2008.02.05},
url = {http://dx.doi.org/10.1038/35011540}
}
@ARTICLE{Keseler2005,
author = {Ingrid M Keseler and Julio Collado-Vides and Socorro Gama-Castro
and John Ingraham and Suzanne Paley and Ian T Paulsen and Martín
Peralta-Gil and Peter D Karp},
title = {EcoCyc: a comprehensive database resource for \textit{Escherichia
coli}},
journal = {Nucleic Acids Res},
year = {2005},
volume = {33},
pages = {D334--D337},
number = {Database issue},
month = {Jan},
abstract = {The EcoCyc database (http://EcoCyc.org/) is a comprehensive source
of information on the biology of the prototypical model organism
\textit{Escherichia coli} K12. The mission for EcoCyc is to contain
both computable descriptions of, and detailed comments describing,
all genes, proteins, pathways and molecular interactions in E.coli.
Through ongoing manual curation, extensive information such as summary
comments, regulatory information, literature citations and evidence
types has been extracted from 8862 publications and added to Version
8.5 of the EcoCyc database. The EcoCyc database can be accessed through
a World Wide Web interface, while the downloadable Pathway Tools
software and data files enable computational exploration of the data
and provide enhanced querying capabilities that web interfaces cannot
support. For example, EcoCyc contains carefully curated information
that can be used as training sets for bioinformatics prediction of
entities such as promoters, operons, genetic networks, transcription
factor binding sites, metabolic pathways, functionally related genes,
protein complexes and protein-ligand interactions.},
doi = {10.1093/nar/gki108},
institution = {SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA.},
keywords = {Computational Biology; Databases, Genetic; \textit{Escherichia coli}
K12; \textit{Escherichia coli} Proteins; Gene Expression Regulation,
Bacterial; Genome, Bacterial; Genomics; Software; User-Computer Interface},
owner = {jfreyre},
pii = {33/suppl_1/D334},
pmid = {15608210},
timestamp = {2008.02.05},
url = {http://dx.doi.org/10.1093/nar/gki108}
}
@ARTICLE{Leskovec2008,
author = {Jure Leskovec and Eric Horvitz},
title = {Planetary-scale views on an instant-messaging network},
year = {2008},
month = mar,
abstract = {We present a study of anonymized data capturing a month of high-level
communication activities within the whole of the Microsoft Messenger
instant-messaging system. We examine characteristics and patterns
that emerge from the collective dynamics of large numbers of people,
rather than the actions and characteristics of individuals. The dataset
contains summary properties of 30 billion conversations among 240
million people. From the data, we construct a communication graph
with 180 million nodes and 1.3 billion undirected edges, creating
the largest social network constructed and analyzed to date. We report
on multiple aspects of the dataset and synthesized graph. We find
that the graph is well-connected and robust to node removal. We investigate
on a planetary-scale the oft-cited report that people are separated
by ``six degrees of separation'' and find that the average path length
among Messenger users is 6.6. We also find that people tend to communicate
more with each other when they have similar age, language, and location,
and that cross-gender conversations are both more frequent and of
longer duration than conversations with the same gender.},
eprint = {arXiv:0803.0939v1 [physics.soc-ph]},
keywords = {Physics - Physics and Society},
owner = {jfreyre},
timestamp = {2008.07.01},
url = {http://arxiv.org/abs/0803.0939}
}
@BOOK{Lipschutz1986,
title = {Estructura de Datos},
publisher = {Mcgraw-Hill},
year = {1986},
author = {Seymour Lipschutz},
pages = {352},
series = {Serie Schaum},
month = dec,
isbn = {0070380015},
owner = {jfreyre},
timestamp = {2008.07.09}
}
@INCOLLECTION{Marconi1967,
author = {Guglielmo Marconi},
title = {Wireless Telegraphic Communication},
booktitle = {Physics 1901--1921},
publisher = {Elsevier Publishing Company},
year = {1967},
series = {Nobel Lectures},
pages = {196--222},
address = {Amsterdam},
owner = {jfreyre},
timestamp = {2008.06.30}
}
@INCOLLECTION{Neidhardt1996,
author = {Neidhardt, F. C. and Savageau, M.},
title = {Regulation beyond the operon},
booktitle = {Escherichia coli and Salmonella: Cellular and Molecular Biology},
publisher = {American Society for Microbiology},
year = {1996},
editor = {Neidhardt, F. C.},
pages = {1310--1324},
address = {Washington D.C.},
edition = {Second},
owner = {jfreyre},
timestamp = {2008.04.18}
}
@BOOK{Nelson2000,
title = {Lehninger Principles of Biochemistry},
publisher = {W. H. Freeman},
year = {2000},
author = {David L. Nelson and Michael M. Cox},
pages = {1200},
edition = {Third},
month = feb,
isbn = {1572599316},
owner = {jfreyre},
timestamp = {2008.07.25}
}
|