Biology Reference
In-Depth Information
DNA microarrays can be used to measure levels of gene expression (mRNA abun-
dance) for tens of thousands of genes simultaneously (
Brazma and Vilo 2000,
Celis et al. 2000, Lockhart and Winzeler 2000
). As a result of the microarray revo-
lution, scientists are faced with an avalanche of data on mRNA expression, or,
as expressed by
Eisenberg et al. (2000)
“piles of information but only flakes of
knowledge.” Microarrays were described in Chapter 6. Another method used in
functional genomics is TILLING.
Tilling
(
t
argeting
i
nduced
l
ocal
l
lesions
i
n
g
enomes) is a method of analyz-
ing gene function that does not require the insertion of TEs to disrupt func-
tion (
Kurowska et al. 2011
). It involves mutagenesis with a chemical mutagen,
such as ethyl methanesulfonate (EMS), and a sensitive method for identifying
single-base mutations in a target gene. It is a type of
reverse genetics
(analysis
from genotype to phenotype). Although about 15,000
D. melanogaster
genes
are annotated, only
≈
6000 genes have a TE insertion. TE insertions disrupt gene
function, causing mutations, or can cause deletions in the gene (and subsequent
mutations) when they move by excision. To study genes lacking TE insertions,
Winkler et al. (2005)
screened genomic DNA from 2086 mutagenized fly lines.
They then screened the library for mutations in three genes. They concluded
that TILLING is useful to obtain mutations in genes of interest in
Drosophila
so
that function can be analyzed.
7.19 Structural Genomics—Another New Horizon?
The
Drosophila
and Human Genome Projects united a large group of geneticists
and others in a coordinated effort to obtain massive amounts of genomic data
in a relatively short time. Such large-scale biology projects were unprecedented
in biology. Another new initiative began in 2000 called The Structural Genomics
Project (
Smith 2000
). Large sums of money were allocated to the project by the
United States and Japan. Once again, the project elicited concern and appre-
hension among biologists because it is difficult and expensive. The Structural
Genomics Project was estimated to cost more and to be more complex than the
Human Genome Project.
Structural genomics
involves large-scale analysis of protein structures and
functions based on gene sequences. Structural genomics developed after the
genome-sequencing projects began, and advances in structural determination of
proteins were obtained. The Structural Genomics Project aims to link sequence,
structural, and functional information and enable the prediction of unknown
structures by homology modeling. The Structural Genomics Project began in
January 1998 and hopes to determine protein structures of 10,000 proteins, one
