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l J. Mol. Zoo., 2013, Vol.3, No.5, 17
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http://ijmz.sophiapublisher.com
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Table 1 Global statistics of the Chinese treeshrew genome (Adopted from
Fan et al., 2013
)
Insert size (bp)
Total data (Gb)
Sequence coverage (X)
(
a) Sequencing
170–800 
187.09
58.47
Paired-end library
2–40000
66.36
20.74
Total
253.45
79.20
N50 (Kb)
Longest (Kb)
Size (Gb)
(
b) Assembly
Contig
22
188
2.72
Scaffold
3656
19270
2.86
Number
Total length (Mb)
Percentage of genome
(
c) Annotation
Repeats
4843686
1001.9
35.01
Genes
22063
743.4
25.98
CDS
166392
31.0
1.08
3
Functional Genes of Treeshrew
The treeshrew genome contains approximately 22 063
protein-coding genes (Fan et al., 2013). Specific
expansion of some gene family happens in the genome of
treeshrew (Figure 1), suchas the immunoglobulin lambda
variable (
IGLV
)
gene family; some pseudogenes and
gene loss occurs as well, for example prostate-specific
transglutaminase 4 gene (
TGM4
)
lost. Treeshrew genome
lost
DDX58
gene, the absence of the gene function in
treeshrew shows that the interruption of immune
response may play an important action causing HCV
infection in treeshrew; Premature stop codon mutations or
frame-shift mutations appearsin some functional genes
leading to functional loss, such a spseudo genization
of the NADPH oxidase(
NOX1
)
gene.
Figure 1 Specific expansion of the immunoglobulin lambda
variable (
IGLV
)
gene family in the treeshrew (Adopted from
Fan et al., 2013)
Note: Gene IDs in red are treeshrew genes
TRIM5 is one of the host restriction factors blocking
retroviral replication. In the treeshrew genome there
exists five tandem repeated copies (Figure 2), one of
the TRIM5 copy has one of theTRIM5 copy has a
CypAretro tranposition and form a TrimCypchimera
transcript, which the appearance of TrimCypindependently
in several primate species and treeshrews implies the potential
importance in retrovirus restriction (Fan et al., 2013).
Figure 2 Trim gene cluster in treeshrew and human (Adopted
from Fan et al., 2013)
28
genes previously considered as primate specific
genes were identified in tree shrew genome such as
psoriasin protein and NKG2D ligands; the treeshrew
genome encompassed the or thologues of almost all
the 209 known vision-related human genes (Fan et al.,
2013).
However, the lack of two cone photoreceptors,
the middle wave-length sensitive proteins, may lead to
the trichromacy in higher primates. The absence of
these proteins is consistent with the fact that treeshrew
is short of green pigment and possess dichromats, which is
similar to some lower primates (Fan et al., 2013).
The treeshrew genome identified 23 known neuro
transmitter transporter proteins, which are important targets