PARENT SESSION
Posters P2D Marine photosynthesis and production. Abstracts (711-719)

Characteristic primary structures of Rubisco in some icealgal diatom species. Ai Yazawa^*,1, Yoshihiro Suzuki¹, ¹ 2946 tsuchiya, Hiratsuka, Kanagawa, Japan

ABSTRACT- Microalgal species could be found in almost all the areas in the world and keep their photosynthetic activities in their own habitats. Many diatom species in icealgal communities blooming massively under sea ice are often found in polar regions and each species in these communities would keep their photosynthetic activities even at low temperature. To keep their photosynthetic activities enzymes active at low temperature (psychrophilic enzymes) must be essential. Thus information about the psychrophilic enzymes is important for analyzing their activities at low temperature. However icealgal species were hard to cultivate and then enough amounts of samples for the analysis could not be collected. In this study we tried to determine the primary structures of psychrophilic enzymes without cultivations. In February 2004 single colonies of 10 dominant diatom species were obtained from icealgal communities in Saroma ko lagoon, Hokkaido, Japan by means of a micromanipulation technique. From each individual colony made of less than 20 cells we extracted total DNA in a buffer solution containing a chelating agent of Chelex 100 (Bio-Rad, Richmond, CA). Some regions for large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were amplified from each extracted DNA by polymerase chain reaction and their sequences were determined. Primary structures of these psychrophilic Rubiscos were compared with that of temperate species of Skeletonema costatum (Grev.) Cleve blooming at 15oC in Tokyo Bay. Same characteristic amino acids were found in primary structures of psychrophilic Rubiscos. The effects of these characteristic structures of psycrophilic Rubiscos on the activity at low temperature will be discussed.

KEY WORDS: icealgae, diatom, psychrophilic, Rubisco