Biology Reference
In-Depth Information
with few gaps (
Adams et al. 2000
). The success of the shotgun approach with
Drosophila
encouraged a similar approach with the human genome (
Venter
et al. 2001
). The actual sequencing of the
Drosophila
genome began in May
1999 at Celera, and by late fall 1999 the sequencing was completed and the
computers had assembled the sequences! The sequences were published in
Science
in March 2000 (
Adams et al. 2000
). The publication of the
Drosophila
genome represented a major milestone for insect molecular genetics (
Hawley
and Walker 2000
). The entire
Drosophila
sequence is available in GenBank
and at FlyBase on the web (
FlyBase Consortium 1997
). FlyBase is a database of
genetic and molecular data and includes genes, alleles, phenotypes, aberra-
tions, transposons, clones, stock lists, locations of
Drosophila
workers, and bib-
liographic references (
Misra et al. 2000
).
The genomes of
Escherichia coli
,
Saccharomyces
,
C. elegans
,
D. melanogas-
ter
, and
Homo sapiens
had been completed ahead of schedule and less expen-
sively than expected by the end of 2000. On February 15, 2001, the sequences of
the human genome were published (
International Human Genome Sequencing
Consortium 2001, Venter et al. 2001
). Since these model organisms had their
genomes sequenced (at great expense), inexpensive and rapid sequencing meth-
ods were developed and used to sequence other genomes (including those of
other arthropods). These next-generation sequencing methods revolutionized
genome sequencing, as described in Section 7.11.
7.10.3
Drosophila
Genome Analysis
Obtaining the DNA sequence is only a first step (
Stein 2001
). Analyses of the
sequence data must be conducted and that is becoming increasingly more
difficult and time-consuming. An early analysis involved “annotating” the
Drosophila
genome; as many genes as possible were identified and the func-
tion of the proteins/gene products was predicted (
Adams et al. 2000, Pennisi
2000b, Reese et al. 2000
). The Genome Annotation Assessment Project (GASP)
assessed the accuracy of the annotation. GASP focused on analysis of a well-
known region of the
Drosophila
genome, and the 12 groups carrying out the
analysis did best in identifying the coding regions, with a success rate averaging
>
95%. The correct intron/exon structures were predicted for
>
40% of the genes.
Almost half the genes in the region were recognized and assigned functions by
homology with known genes. However, less than one-third of the promoters in
the region were found by the GASP group (
Reese et al. 2000
). Subsequent anno-
tations and evaluations were required to refine and improve on these initial
annotations.
