Biology Reference
In-Depth Information
Progress has been much more general than retrogression.
Charles Robert Darwin (1809-1882)
The per-luc reporter gene constructs described in the last
chapter are an excellent tool for identifying cells,
tissues, and organs with their own circadian rhythms.
However, many genes other than the period gene are
expressed in a circadian manner. Some of these genes,
such as clock and timeless, have already been identified
and studied, but there are undoubtedly others currently
unidentified. To understand circadian functioning in
greater depth, we would like to be able to identify and
characterize all genes that are under circadian control.
Chapter 12
As we have seen, genes and proteins work together in
living organisms in an intricate network to ensure proper
functioning at the system level. Traditional methods
that are designed to study single genes are incapable of
capturing these complex dynamics, and new tools are
needed to investigate these interactions. The best tool
currently available for simultaneously examining the
expression of multiple genes is the microarray, also called
the DNA array, the DNA chip, or the gene chip.
Microarrays are now widely used in biological and
biomedical research, as it becomes increasingly clear that
to understand biological function we must discover and
understand patterns of gene expression. Microarrays
allow us to analyze the expression of all of the thousands
of genes of an organism. This also allows us to identify
genes expressed in a rhythmic fashion.
USING MICROARRAYS
TO STUDY GENE
EXPRESSION
PATTERNS
Fabricating and Using Microarrays
Analysis of Microarray Data
Microarrays and Circadian Rhythms
Microarray technology provides a means to examine the
effect of gene regulation on physiologic functions, to
study the genetic mechanisms of certain diseases, and to
assess the effectiveness of new therapies. Applications
include studying embryonic development in order to
prevent and treat birth defects, investigating pancreatic
function to improve treatment for diabetes, and
examining cancer cell behavior for the purpose of
designing new approaches to treatment.
For example, cancer is not a single disease. There are
many different kinds of cancer, arising in different organs
and tissues through the accumulated mutation of
multiple genes. Traditionally, cancer diagnoses have
relied on microscopic examination of cell appearance,
which may be incapable of distinguishing among cancer
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