My research topics

It seems stupid not to have mentioned my research topics, as a scientist. (Thanks Jp, for reminding me this matter!)

I was educated in Department of Fisheries Science, Kyushu University, and started to study Fish Immunology (clarifying immune system of fish) as a PhD student. Especially my major study subject is the complement system, a multi-component humoral system in the blood, fighting against microbial invasion.
In the medical research field, or even in a general immunology, the complement system has been regarded as something complicated with many components with just numbers, such as C1, C2 ,,,, down to C9. The fact that the numbered components do not always react in the numbered order, for example C1 is followed by C4, then C2, C3.
Nevertheless, the complement system has been very interesting for me. It is a kind of harmonized system composed of diverse range of protein families, it show wide variety of biological functions, and it is very well conserved over evolution.

I spent two years of my master course period for attempts to purify C4 protein from carp serum, resulting in vain. I also spent six years to purify and clone C3, factor B, and factor D, the essential components in an antibody-independent activation pathway of the complement system, from carp, this time fortunately resulting in acquisition of PhD but far later in 2001. Furthermore I also spent several years to work on other components with students and international collaborators, using mainly carp fish.

The most interesting and exciting feature of FISH complement system is that the fish system is much more complex than that of mammals, which has been regarded as a most sophisticated and developed one. Fish complement components are present as multiple copies of isotypes/isoforms, with significant sequence and, possibly functional, divergence. We have hypothesized the diversity as an evolutionary strategy to expand innate immune ability to recognize wide range of pathogens which should be more densely present and abundant in aqueous environment around fish.

Now research on innate immunity is a big trend, but this trend is mainly driven by Toll-like receptors, lectins, and so on, but not so much by the complement (pity though). But the complement system is there and everywhere in the body, and also in almost every animal species including vertebrates and invertebrates. Why not study more! That's the one crucial to live.

My dream is to make my lab as a Mecca for the complement research for lower vertebrates, and accordingly for comparative immunology, of Japan and even worldwide.

You may find a recent review of fish complement system as follows: one from me, and another from my friend, Oriol.
If you would like to have their PDF, please let me know.

Diversified components of the bony fish complement system: more genes for robuster innate defense?
Nakao M, Kato-Unoki Y, Nakahara M, Mutsuro J, Somamoto T.
Adv Exp Med Biol. 2006;586:121-38. Review.

Expansion of genes encoding complement components in bony fish: biological implications of the complement diversity.
Nakao M, Mutsuro J, Nakahara M, Kato Y, Yano T.
Dev Comp Immunol. 2003 Oct;27(9):749-62. Review.

Recent advances on the complement system of teleost fish.
Boshra H, Li J, Sunyer JO.
Fish Shellfish Immunol. 2006 Feb;20(2):239-62.