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PLASTID FATTY ACID BIOSYNTHESIS IN THE DIATOMS NITZSCHIA ALBA AND NITZSCHIA LAEVIS
Author(s) -
McGinnis K.M.,
Sommerfeld M.R.
Publication year - 2000
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1999.00001-137.x
Subject(s) - plastid , biology , chloroplast , nitzschia , biochemistry , photosynthesis , biosynthesis , fatty acid , botany , thylakoid , fatty acid synthesis , gene , ecology , phytoplankton , nutrient
The role of the plastid in fatty acid biosynthesis in the non‐photosynthetic diatom Nitzschia alba was studied and compared to that in the photosynthetic, closely related Nitzschia laevis. Transmission electron microscopy was used to analyze structural features of the plastid that may be relevant to biochemical function. Typical of a photosynthetic diatom, N. laevis had a chloroplast envelope composed of four membranes, and had abundant chloroplast ribosomes. The leucoplast of N. alba also had a multi‐membrane envelope, chloroplast ribosomes, and a genome that encodes plastid specific proteins. This suggested that the plastid of N. alba may still possess the biochemical functions of the chloroplast, aside from photosynthesis. To determine whether plastidial fatty acid biosynthesis occurred in N. alba , the response of the two diatoms to the compound thiolactomycin was compared. Thiolactomycin has been shown to effect keto‐acyl‐ACP‐synthases, and specifically inhibits the plastidial fatty acid biosynthetic pathway. While growth of N. alba was not impacted by thiolactomycin as in N. laevis , neutral lipid accumulation and fatty acid composition was impacted by thiolactomycin in both organisms. These findings suggest that the plastidial fatty acid biosynthetic pathway does exist in the leucoplast of N. alba , although it lacks photosynthetic capacity.