Interference 103,579
The Kuipers 1995 publication reported a higher percentage of
clones which inhibited PGBSS gene expression using the antisense
GBSS cDNA constructs than were inhibited using the corresponding
genomic GBSS DNA constructs (VDX 4, p. 752, col. 1; HR 343,
col. 1)(emphasis added):
The origin of the GBSS sequence was shown to be an
important factor in determining the efficacy of antisense
inhibition. The full-length GBSS cDNA (pGB50, pKGBA50)
and genomic DNA (pGBA10, pKGBA10) constructs were all
found to be capable of complete inhibition of GBSS gene
expression, but it was shown that the antisense GBSS cDNA
constructs resulted in complete inhibition of GBSS gene
expression in a higher percentage of transgenic potato
clones (Table 1). This was also observed for the partial
cDNA construct pKGBA55 as compared to the corresponding
partial genomic construct pKGB25. The percentage of
clones with inhibited GBSS gene expression was shown to
be higher for the antisense GBSS cDNA constructs than for
the genomic DNA constructs (Fig. 2A). The presence of
intron sequences in the genomic constructs might contribute
to the observed differences in antisense inhibition. The
full length GBSS gene contains 12 introns (van der Leij
et al. 1991), four of which are also present in the gene
fragment used for pKGBA25. These introns will not be
processed when present in antisense orientation. . . .
The supposed differences . . . can be explained by the
differences in the GC content, which is 42.7% for exon
(cDNA) sequences and 33% for intron sequences. . . .
In this way, the presence of intron sequences with a
low GC content might reduce the efficacy of antisense
inhibition of gene expression.
The Kuipers 1995 publication speculates that the presence of
intron sequences with a low GC content in the genomic antisense
inserts reduces the efficiency of antisense inhibition of GBSS
gene expression and results in the differences in antisense
inhibition observed. The Kuipers 1995 publication shows that
-110-
Page: Previous 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 Next
Last modified: November 3, 2007