Sentence examples for be difficult to sequence from inspiring English sources
In Sanger sequencing, the underlying sequence can give rise to secondary structure which can be difficult to sequence, for example in GC-rich regions.
Zero coverage regions that could not be ascribed to deletions compared to the H37Rv reference genome were all located at loci with higher than average GC content, mainly in PE-PGRS genes (Polymorphic GC Rich Sequences), that are known to be difficult to sequence due to their high GC content [14], [15].
First, nonrecombining portions of the genome tend to accumulate repetitive sequences that can be difficult to sequence and map.
Second, several genomes were poorly sequenced, however most of them were high GC% draft genome, known to be difficult to sequence using Illumina sequencing [ 45].
This range in coverage might be attributed to homopolymeric stretches as these areas may be difficult to sequence due to chemistry-related limitations [ 20].
In addition to the PW method, we adopted another approach based on TPS, particularly for cDNA clones that could be difficult to sequence with the primer walking method [ 30- 32, 61].
PCR products that were difficult to sequence directly were cloned using the pGEM-T Vector System II (Promega, Madison, WI, USA).
The main reason the 6-year project became a "real nightmare," says TIGR's Malcolm Gardner, is that Plasmodium's DNA is unstable when it's reproduced in bacteria--a necessary step before the actual sequencing--and is difficult to sequence.
However, a relatively small percentage of DNA extracted from paraffin-embedded samples was difficult to sequence.
A second potentially negative factor is the presence of long poly-G, poly-C, and poly-A repeats that are difficult to sequence through.
This dual-method approach can be adapted and applied to other mixed assemblages of organisms, particularly those that are difficult to sequence and/or are not readily amenable to current bioengineering methods (site directed mutagenesis, miRNA knockdowns, etc).
