“…In teleost, the IgM heavy chain possesses a translocon domain organization similar to the mammalian and amphibian IgM, that is V H1-n -D 1-n -J H1-n -C H1 -C H2 -C H3 -C H4 for secretory form and two additional transmembrane exons (TM1 and TM2) for membrane bound form (Litman et al 1999). To date, IgM heavy-chain genes have been cloned from various fish species including catfish, I. punctatus (Ghaffari and Lobb 1989;Wilson et al 1990), ladyfish, E. saurus (Amemiya and Litman 1990), Atlantic cod, G. morhua L., (Bengtén et al 1994), Atlantic salmon, S. salar L. (Hordvik et al 1992(Hordvik et al , 1997, rainbow trout, O. mykiss (Lee et al 1993;Andersson and Matsunaga 1993;Hansen et al 1994), holostean fish (bowfin, Amia calva and gar, Lepisosteus osseus) (Wilson et al 1995), zebrafish, Danio rerio (Danilova et al 2000), Antarctic teleost, Trematomus bernacchii (Coscia et al 2000), mandarin fish, Siniperca chuatsi (Zhang et al 2003), Japanese flounder, Paralichthys olivaceus (Lee et al 2001;Srisapoome et al 2004), Pufferfish, Takifugu rubripes (Saha et al 2005) and grouper, Epinephelus coioides (Cheng et al 2006). These studies revealed that the IgM heavy chain of teleosts shows differences in gene number, sequence diversity, and genetic organization of the putative elements.…”