Browsing by Author "Dong, Zhiguo"
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- Domain-dependent evolution explains functional homology of protostome and deuterostome complement C3-like proteinsPublication . Peng, Maoxiao; Li, Zhi; Cardoso, João; Niu, Donghong; Liu, Xiaojun; Dong, Zhiguo; Li, Jiale; Power, DeborahComplement proteins emerged early in evolution but outside the vertebrate clade they are poorly characterized. An evolutionary model of C3 family members revealed that in contrast to vertebrates the evolutionary trajectory of C3-like genes in cnidarian, protostomes and invertebrate deuterostomes was highly divergent due to independent lineage and species-specific duplications. The deduced C3-like and vertebrate C3, C4 and C5 proteins had low sequence conservation, but extraordinarily high structural conservation and 2-chain and 3-chain protein isoforms repeatedly emerged. Functional characterization of three C3-like isoforms in a bivalve representative revealed that in common with vertebrates complement proteins they were cleaved into two subunits, b and a, and the latter regulated inflammation-related genes, chemotaxis and phagocytosis. Changes within the thioester bond cleavage sites and the a-subunit protein (ANATO domain) explained the functional differentiation of bivalve C3-like. The emergence of domain-related functions early during evolution explains the overlapping functions of bivalve C3-like and vertebrate C3, C4 and C5, despite low sequence conservation and indicates that evolutionary pressure acted to conserve protein domain organization rather than the primary sequence.
- Dopamine beta-hydroxylase and its role in regulating the growth and larval metamorphosis in Sinonovacula constrictaPublication . Li, Zhi; Niu, Donghong; Peng, Maoxiao; Xiong, Ya; Ji, Jie; Dong, Zhiguo; Li, JialeDopamine beta-hydroxylase (D beta H) plays a key role in the synthesis of catecholamines (CAs) in the neuroendocrine regulatory network. The D beta H gene was identified from the razor clam Sinonovacula constricta and referred to as ScD beta H. The ScD beta H gene is a copper type II ascorbate-dependent monooxygenase with a DOMON domain and two Cu2_monooxygen domains. ScD beta H transcript expression was abundant in liver and hemolymph. During early development, ScD beta H expression significantly increased at the umbo larval stage. Furthermore, the inhibitors and siRNA of D beta H were screened. After challenge with D beta H inhibitor, the larval metamorphosis and survival rates, and juvenile growth were obviously decreased. Under the siRNA stress, the larval metamorphosis and survival rates were also significantly decreased. Therefore, ScD beta H may play an important regulating role in larval metamorphosis and juvenile growth.
- RNAi-mediated knock-down of the dopamine beta-hydroxylase gene changes growth of razor clamsPublication . Li, Zhi; Peng, Maoxiao; Power, Deborah; Niu, Donghong; Dong, Zhiguo; Li, JialeDopamine beta-hydroxylase (D beta H) plays an essential role in the synthesis of catecholamines (CA) in neuroen-docrine networks. In the razor clam, Sinonovacula constricta a novel gene for D beta H (ScD beta H-alpha) was identified that belongs to the copper type II ascorbate-dependent monooxygenase family. Expression analysis revealed ScD beta H-alpha gene transcripts were abundant in the liver and expressed throughout development. Knock-down of ScD beta H-alpha in adult clams using siRNA caused a reduction in the growth rate compared to control clams. Reduced growth was associated with strong down-regulation of gene transcripts for the growth-related factors, platelet derived growth factors A (PDGF-A) (P < 0.001) 24 h after ScD beta H-alpha knock-down, vascular endothelial growth factor (VEGF1) (P < 0.001) and platelet derived growth factor B (PDGF-B-2)(P < 0.001) 24 h and 48 h after ScD beta H-alpha knock-down and transforming growth factor beta (TGF-beta 1) (P < 0.001) 48 h and 72 h after ScD beta H-alpha knock-down. Taken together the results suggest that the novel ScD beta H-alpha gene through its role in CA synthesis is involved in growth regulation in the razor clam and possibly other bivalves.