Changes in fatty acid
profiles of thermo-intolerant and thermo-tolerant marine diatoms during
temperature stress
J.M. Rousch, S.E. Bingham, M.R. Sommerfeld-2003
Journal of Experimental Marine Biology and Ecology, 295(2): 145-156
Abstract:
Fatty acid composition and degree of fatty acid
saturation during temperature stress in thermo-intolerant (Phaeodactylum
tricornutum) and thermo-tolerant (Chaetoceros muelleri) marine
diatoms were investigated. A greater number of fatty acids were observed in C.
muelleri than in P. tricornutum regardless of treatment. The
major fatty acids detected were 14:0, 16:0, 16:1, 16:2, 16:3, 18:0,
18:1(n-9)c, 18:2(n-6) and 20:5(n-3) with additional fatty acids 18:1(n-9)t
and 20:4(n-6) detected in C. muelleri. Short duration (2 h)
temperature increase above optimal growth temperature had a greater effect
on fatty acid composition in C. muelleri than in P. tricornutum
and the degree of fatty acid saturation was affected more by temperature in C.
muelleri than in P. tricornutum during both short and long
duration (24 h) treatments. Total protein assay results suggest that P.
tricornutum, but not C. muelleri, was undergoing stress under our
growing conditions although lipids in both diatoms were affected by
increased temperature. Immunodetection of proteins with anti-rubisco
indicates that the rubisco large subunit was undergoing greater turnover in C.
muelleri than in P. tricornutum. However, the integrity of
rubisco as a suitable indicator of lipid status needs further study. This
work supports the hypothesis that a particular temperature, and not
treatment duration, has the greater effect on changes in fatty acid
composition. Furthermore, changes in fatty acid composition and degree of
fatty acid saturation occurred more quickly in the diatoms in response to
increased temperature than previously observed in nutrient starvation
studies. Since diatom lipids represent an important resource for growth and
reproduction of marine animals, the rapid alteration of their lipid
composition under temperatures normally encountered in marine environments
warrants further study.
(Department
of Plant Biology, Arizona State University, Box 871601, Tempe, AZ
85287-1601, USA, e-mail of M.R. Sommerfeld: milton.sommerfeld@asu.edu)