SINGLE-CELL PIGMENTATION OF PORPHYRA-LINEARIS ANALYZED BY FOURIER-TRANSFORM MULTI-PIXEL SPECTROSCOPY AND IMAGE-ANALYSIS

The novel method of Fourier transform multi-pixel spectroscopy was use d for the nondestructive analysis of and comparison of pigmentation in different reg ions of live thalli of the red alga Porphyra linearis. Because the thallus in this alga consists of a monolayer of nonoverlap ping cells, we were able to analyze the pigmentation of single cells b y combining light absorbance with natural fluorescence data. From the image of each cell in the vegetative male and female reproductive and holdfast regions, more than 4 x 10(4) fluorescence and absorbance spec tra were obtained. Specific pigments in the different regions were loc alized by the use of a software program of similarity mapping followed by image construction The reconstructed images revealed subcellular l ocalization of each pigment according to specific spectroscopic finger prints. The results showed that the vegetative and female reproductive cell types had a significantly higher content of phycoerythrin than o f phycocyanin, and quite similar chlorophyll a levels. Most of the hol dfast cells were poorly pigmented, but had more chlorophyll a than phy coerythrin or phycocyanin. The male reproductive cells contained only traces of pigments. Thus, by using Fourier transform multipixel spectr oscopy, we were able to characterize the pigmentation of different reg ions of the thallus and follow the distribution patterns of the differ ent pigments on the subcellular level along the differentiation gradie nt of the alga.