Project 6:
Transcriptomics of the bovine preimplantation embryo
Heiner Niemann, James Adjaye
In
cattle breeding, early embryonic mortality in the range of 35-50% is
associated with enormous economic losses. Moreover, the bovine embryo
is an attractive complement to the mouse embryo for studying mechanisms
of preimplantation mammalian development.
The major goal of this project is the analysis of the transcriptome in
in vivo derived bovine preimplantation embryos using a bovine
cDNA-array. Early stages up to 16-cell embryos are recovered from the
oviducts of donor animals by using laparoscopic techniques. Later
stages are flushed from the uterus. Embryos are pooled by stage, RNA is
extracted and amplified. The mRNA expression profiles are analyzed
using bovine Affymetrix arrays (22 k). Expression data are subjected to
bioinformatic evaluation such as cluster and pathway analyses to
identify expression patterns and regulatory mechanisms. Data will be
stored in an open-access database. In parallel a custom bovine embryo
array is developed, which is – in the first stage – based
on previous results obtained by RT-PCR studies. Differentially
expressed genes identified by the Affymetrix studies will be integrated
in the embryo array. The final version of this embryo array will then
be used to compare the transcriptome profiles of different stages of in
vivo derived bovine embryos with those of in vitro produced or cloned
embryos to identify transcriptome alterations and deviations from the
in vivo “gold” standard. These first holistic and dynamic
transcriptome studies of different sources of bovine preimplantation
embryos represent an essential contribution to the systematic analysis
of embryo-maternal communication.
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