The genome of the miiuy croaker reveals well-developed innate immune and sensory systems.

The miiuy croaker, Miichthys miiuy, is a representative Sciaenidae known for its exceptionally large otoliths. This species mainly inhabits turbid aquatic environments with mud to sandy mud bottoms. However, the characteristics of the immune system of this organism and its specific aquatic environment adaptations are poorly understood.

Characterization and evolutionary analysis of duplicated C7 in miiuy croaker.

The complement system, as one of the most sophisticated innate immune system, plays an important role in defense against invading microorganisms. The complement component C7 participates in the cytolytic phase of complement activation through a series of polymerization reactions with other terminal complement components. In this study, we derived two C7 genes from the whole genome of miiuy croaker which were the consequence of the fish-specific genome duplication.

Characterization of the duplicate L-SIGN and DC-SIGN genes in miiuy croaker and evolutionary analysis of L-SIGN in fishes.

Dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN/CD209) and liver/lymph node-specific ICAM-grabbing non-integrin (L-SIGN/CD299) which are homologues of DC-SIGN are important members in C-type lectin receptors family as key molecules to recognize and eliminate pathogens in the innate immune system. DC-SIGN and L-SIGN have become hot topics in recent studies which both served as cell adhesion and phagocytic pathogen recognition receptors in mammals. However, there have been almost no studies of DC-SIGN and L-SIGN structure and characters in fish, only DC-SIGN in the zebrafish had been studied.

Genomic characterization and expression pattern of Bf/C2 and C4 in miiuy croaker and molecular evolution analysis on mammals and fishes.

The complement system plays an important role in both innate and adaptive host defense against the invading microorganisms in vertebrates. It can be activated by three pathways: the classical, alternative and lectin pathways. Bf/C2 and C4, as members of complement, play a pivotal role in the activation of the complement system.

The evolutionary analysis on complement genes reveals that fishes C3 and C9 experience different evolutionary patterns.

Complement is a humoral factor of innate immunity and plays an essential role in altering the host of the presence of potential pathogens and clearing of invading microorganisms. The third complement component (C3) not only is regarded as the crossing of the three pathways of complement activation, but also serves one of the bridges linking innate and acquired immunity. The nine complement component (C9) can combine with C5b, C6, C7 and C8 to form MAC which bounds to the surface of microorganisms to kill them.