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Invertebrate
Immunity / Evolution of the Animal Immune System
Development of Hemichordates / Evolution of Chordates
I study the foundations of the animal immune system in marine sponges.
The immune system of the invertebrates remains unappreciated although
it is evident that all animals must resist attacks by pathogens
and other organisms. In this regard sessile marine invertebrates
must protect their individual integrity from encroachment by adjacent
animals competing for space on the substratum. Our lab has identified
the immunocytes of marine sponges and are pursuing experiments to
identify, molecularly clone and characterize the functional molecules
of sponge immune cells. The receptors that recognize contact with
non-self cells, the molecules of the signaling pathways that lead
to activation of immune responses upon contact with foreign cells
and immune effector molecules are targets of these molecular studies.
My lab is studying developmental master control genes that specify
vertebrate structures in the hemichordate acorn worm, Ptychodera
flava. We have cloned and characterized P. flava developmentally
expressed genes central to the development of notochord, dorsal
brain and gill slits, structures diagnostic chordates/vertebrates.
Characterization of the expression and the developmental role of
these genes, especially the role of genes that specify the vertebrate
brain, will be used to understand the evolutionary pathways that
have lead to production of the chordate body plan. Recent data explores
the conservation of the foundation nervous system in bilateral animals,
with the protostomes emphasizing a ventral component and the chordates
emphasizing a dorsal component.
Representative
publications
Nakajima , Humphreys , Kaneko, Tagawa. 2004. Development and neural
organization of the Tornaria larva of the Hawaiian hemichordate,
Ptychodera flava. Zool. Sci. 21:69-78 (2004).
Tagawa, Satoh, Humphreys. 2001. Molecular studies of hemichordate
development: a key to understanding the evolution of bilateral animals
and chordates. Evol. Dev. 3:443-454.
Tagawa, Humphreys, Satoh. 2000. T-Brain expression in the apical
organ of hemichordate Tornaria larvae suggests its evolutionary
link to the vertebrate forebrain. Molec Devel Evol 288:23-31.
Yin, Humphreys. 1996. Acute histoincompatibility reactions and gray
cells in the marine sponge, Callyspongia diffusa. Biol
Bull 191:159-167.
Humphreys, Reinherz. 1994. Invertebrate Immune recognition, natural
immunity and the evolution of positive selection. ImmunologyToday
15:316- 320.
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