3.5 | Expanded or contracted gene families related to
the adaptation of B. schroederi
To better understand the adaptation to the specific habitat and
intestinal environment of the giant panda, we analyzed the expanded and
contracted genes in B. schroederi compared with three roundworms
(A. suum , P. univalens and T. canis) .
We identified expanded gene families with functions involved in striated
muscle contraction (GO:0006941), nematode larval development
(GO:0002119), larval feeding behavior (GO:0030536), chitin metabolic
process (GO:0006030) and actin cytoskeleton organization (GO:0030036).
The most significantly enriched GO term was the straight muscle
contraction, which was largely due to the highly significant expansion
of the actin family (Fig. 3a, 3d). KEGG enrichment showed that the
number of genes involved in metabolic pathways, including drug
metabolism (metabolism of xenobiotics by cytochrome P450, ko00980;P <0.01) and autoimmunity (ko05130, ko05100;P <0.01), exhibited significant changes (Fig. 3a). We
observed an expansion of the gene family involved in positive regulation
of eating behavior (Fig. 3b). Finally, we found that B.
schroederi has 654 unique annotated proteins, which were mainly
enriched in the synthesis and recycling pathways of essential amino
acids especially the degradation of valine, leucine and isoleucine
(ko00280, P <0.01; Fig. 3c).