Identification of ceramide-phosphorylethanolamine in oomycete plant pathogens: Pythium ultimum, Phytophthora infestans, and Phytophthora capsici.

Cellular lipids were extracted from three species of Oomycete plant pathogens (Pythium ultimum, Phytophthora infestans, and Ph. capsici) and analyzed via normal-phase high-performance liquid chromatography with flame-ionization detection. The most abundant polar lipids in each of the three species were the polar membrane lipids, phosphatidylethanolamine (PE), phosphatidylcholine, and a phosphosphingolipid that eluted soon after PE. Structural analysis via mass spectrometry and nuclear magnetic resonance spectrometry revealed that the phosphosphingolipid was ceramide phosphorylethanolamine (Cer-PE). The most abundant molecular species of Cer-PE in P. ultimum had a molecular weight of 670.5, contained an unusual 19-carbon branched triunsaturated sphingoid (C19-delta 4, 8, 10, 9-methyl long-chain base) and palmitic acid as the amide-linked fatty acid. The most abundant molecular species of Cer-PE in Ph. infestans had a molecular weight of 714.5, contained a common 16-carbon 1,3 di-OH sphingoid, and erucic (cis 13-docosenoic, C22-delta 13) acid as the amide-linked fatty acid. The Cer-PE in Ph. capsici comprised a mixture of each of the two molecular species found in P. ultimum and Ph. infestans.

The computer-assisted interpretation of copolymer mass spectra.

A computer program called MSCOPOL has been developed to aid in the interpretation of copolymer mass spectra. The program reads the mass spectrum, calculates the most likely monomer masses via correlation or Fourier transform methods, determines possible end group masses based on the monomer masses, and can then search monomer and end group data bases for likely chemical moieties. Refinement of the end group result is possible by calculation of the monomer ratio and degree of polymerization as a function of end group mass. The program is written in Microsoft Visual Basic and runs on an IBM compatible PC. Applications are shown for polystyrene, poly(N-vinyl pyrrolidone/vinyl acetate), and poly(ethylene oxide/propylene oxide).