作业帮求翻译一段生物论文,请不要用翻译软件.
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求翻译一段生物论文,请不要用翻译软件.
Genomic context of stably and unstably expressed
transgenes
Characteristics of flanking plant DNA
Only a few reports provide comprehensive data on the
genomic context of transgenes in genetically well characterized
lines [24,25,26··]. Recurring sequence motifs have
appeared in plant DNA that flanks transgenes introduced
using binary vectors and Agrobacterium-mediated transfer
into diploid and tetraploid Nicotiana species. Of twelve
transgene loci examined so far ([25,26··]; AJM Matzke,
J Jakowitsch, F Mette, C Kunz, H van der Winden,
unpublished data), matrix-attachment regions (MARs)
have been found in the flanking regions of four; various
microsatellites in three; highly repetitive tandem repeats
in two; and retroelement remnants in five. Except for
the frequent presence of binary vector sequences (see
below), the remaining DNA contains no defining characteristics.
Prokaryotic sequences, a GA-rich microsatellite,
retroelement remnants, and a tandem repeat array are the
primary elements correlated so far with silencing. MARs
have been associated with some stably expressed inserts
[26··]. In work on plant species other than Nicotiana,
highly repetitive sequences have been found adjacent to
an unstable transgene in petunia [24]. Molecular analysis
of three integration site structures in rice transformed by
direct gene transfer indicated a common AT-rich repetitive
sequence and telomeric repeats at all three junctions of the
target genome [27]. Additional studies on DNA sequences
flanking transgene inserts are required to substantiate the
current view that certain repeats or prokaryotic sequences
tend to be associated with poorly expressed or silenced
inserts.
Genomic context of stably and unstably expressed
transgenes
Characteristics of flanking plant DNA
Only a few reports provide comprehensive data on the
genomic context of transgenes in genetically well characterized
lines [24,25,26··]. Recurring sequence motifs have
appeared in plant DNA that flanks transgenes introduced
using binary vectors and Agrobacterium-mediated transfer
into diploid and tetraploid Nicotiana species. Of twelve
transgene loci examined so far ([25,26··]; AJM Matzke,
J Jakowitsch, F Mette, C Kunz, H van der Winden,
unpublished data), matrix-attachment regions (MARs)
have been found in the flanking regions of four; various
microsatellites in three; highly repetitive tandem repeats
in two; and retroelement remnants in five. Except for
the frequent presence of binary vector sequences (see
below), the remaining DNA contains no defining characteristics.
Prokaryotic sequences, a GA-rich microsatellite,
retroelement remnants, and a tandem repeat array are the
primary elements correlated so far with silencing. MARs
have been associated with some stably expressed inserts
[26··]. In work on plant species other than Nicotiana,
highly repetitive sequences have been found adjacent to
an unstable transgene in petunia [24]. Molecular analysis
of three integration site structures in rice transformed by
direct gene transfer indicated a common AT-rich repetitive
sequence and telomeric repeats at all three junctions of the
target genome [27]. Additional studies on DNA sequences
flanking transgene inserts are required to substantiate the
current view that certain repeats or prokaryotic sequences
tend to be associated with poorly expressed or silenced
inserts.
参考答案\x09坚持做你自己,而不是被别人修改的面目全非.