Sequence Analysis of 47
Low-abundance ESTs Expressed in Early Human Embryo
GOU De-Ming，LI Wen-Xin，XIA Zong-Pin，HUANG Jian and JIANG Da-He
( College of Life Sciences，Wuhan University，Wuhan 430072，China )
Abstract The
availability of high quality cDNA libraries has proven essential to positional
gene cloning efforts，differential gene expression studies and
EST sequencing/mapping projects.In order to isolate and identify new genes
expressed during early human development，a 3-week-old human embryo cDNA
library was constructed，and a pre-screening procedure was used to
select cDNAs corresponding to low abundance mRNAs. 6 508 clones were hybridized
with a mixture of cDNA probes.Approximately 1 677 clones (26%) did not hybridize
with the cDNA probes，and represent low abundance mRNAs as well
as empty vectors.Partial sequences were generated from one or both end of 47
low abundance cDNA clones，and the sequences comparisons with
genetic databases revealed that 38.3% of them was annotated human genes，10.6% was highly similar to
those from either human or other species，40.4% was partial sequence
matched with ESTs that had already been detected，and 8.5% of the cDNAs appeared
to be unknown in the genetic databases.
Key Words early human embryo；ESTs；DNA sequence
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