[Date Prev][Date Next][Thread Prev][Thread Next]   [Date Index] [Thread Index] [Author Index

Re: Genetic Regulatory Network



Hi Jerry,
 
The first sentence in your post gave me great hope that perhaps the flaws in the reductionistic mode of analysis were finally being spotlighted, especially as applied to living systems...
 
Jerry Zhu wrote: One of the hottest research topic in Genome Science is
the interaction between genes. Genetic Regulatory
Network is one of the recent focuses to understand
metabolic pathways and bioprocesses.
 
But then I went on the net and did some research. I found a lot of this kind of thing:
 
Taken from: http://www.cs.unm.edu/~patrik/networks/networks.html
 The traditional approach to research in Molecular Biology has been an inherently local one, examining and collecting data on a single gene, a single protein or a single reaction at a time. This is, of course, the classical reductionist stance: to understand the whole, one must first understand the parts. Over the years, this approach has led to remarkable achievements, allowing us to make highly accurate biochemical models of such favorites as bacteriophage Lambda.

However, with the advent of the "Age of Genomics" an entirely new class of data is emerging. Can we really expect to construct a detailed biochemical model of, say, an entire yeast cell with some 6000 genes (only about 1000 of which were defined before sequencing started, and about 50% of which are clearly related to other known genes), by analyzing each gene and determining all the binding and reaction constants one by one? Likewise, from the perspective of drug target identification for human disease, we cannot realistically hope to characterize all the relevant molecular interactions one-by-one as a requirement for building a predictive disease model.

There is a need for methods that can handle this data in a global fashion, and that can analyze such large systems at some intermediate level, without going all the way down to the exact biochemical reactions. At the very least, such an analysis could help guide the traditional pharmacological and biochemical approaches towards those genes most worthy of attention among the thousands of newly discovered genes. Ideally, a sufficiently predictive and explanatory model at an intermediate level could obviate the need for an exact understanding of the system at the biochemical level.
They don't want to understand the interaction between the genes as a causal force in gene _expression_. They simply want a way to make their number crunching easier and less "complicated". They still don't get it.
 
Frustration!
 
Judith
 
----- Original Message -----
From: Jerry Zhu
To: ***
Sent: Wednesday, January 26, 2005 8:04 PM
Subject: [ROSEN] Genetic Regulatory Network

One of the hottest research topic in Genome Science is
the interaction between genes. Genetic Regulatory
Network is one of the recent focuses to understand
metabolic pathways and bioprocesses. GRNs act as
analog biochemical computers to specify the identity
and level of _expression_ of a group of targeted genes.
Its output is the constellation of RNAs and proteins
encoded by target genes.  Time series _expression_ data
obtained from DNA microarrays is one of the most
useful kinds of data used to construct and test GRNs.

There are numerous techniques to model GRNs or the
behavior of a cell: boolean networks, Petri nets,
Bayesian networks, cluster analysis etc. There are
even genetic/metabolic circuit networks where genes,
metabolic enzymes, and proteins are modeled as nodes
with the relationship between activation, inhibition
and mediation as links.  GRN models can be used to
identify genetic diseases and estimate the effects of
medications.

My doubt is that such efforts will fall into the fate
of the hype of artifical intelligence for the
following three reasons:

First, using mathematic model to describe celluar
process is non-holistic in the sense of ignoring the
matter aspect of life. Cellular systems are not
reducible to formal systems.

Second, mathematic based GRN models ignore the
hierarchical dynamics.  Current GRN use one level
mathematic models only.

Third, it is not historical.  Every form of life has a
history.  It is the history that answers why
questions.

My guesture is that today's development activities of
biological sciences such as molecular biology and all
social sciences are questionable.  The net effect of
such activities is the waste of resources and
intellectual work.  The focus of science today is
mostly deductively representing theories rather than
the understanding of inductive development efforts or
scientific activities. 

Jerry





__________________________________
Do you Yahoo!?
Read only the mail you want - Yahoo! Mail SpamGuard.
http://promotions.yahoo.com/new_mail