发状念珠藻藻殖段的分化及其光合特性的研究

Differentiation of Hormogonia and Photosynthetic Characterization of Nostoc flagelliforme

Hormogonia of Nostoc flagelliforme is one of the developmental stages in the life cycle of cyanobacterium. High yields of pure hormogonia were obtained by weak light (the filaments were covered by sterilized sand for blocking light), red light, white light plus DCMU (3, 4-dichlorophenyl-1, 1-dimethylurea) in the culture. These pure fractions of hormogonia allowed the study of physiological measurements in comparison to vegetative filaments. The photosynthesis in the hormogonia and the vegetative filaments was characterized by fluorescence emission spectra at 77 K, absorption spectrum and oxygen evolution. Absorption spectrum of the hormogoia and vegetative filaments did not reveal difference. The data indicated the similarity of pigment contents between hormogonia and vegetative filaments. Some differences were observed in oxygen evolution of vegetative filaments and hormogonia in the temperature range of 15 ℃ to 45 ℃ and light intensity around 110 μmol·m-2·s-1 to 1200 μmol·m-2·s-1. The fluorescence emission spectra showed that energy distribution between the two photosystems in mature colonies was more balance than in hormogonia. The absorption of light energy in phycobilisomes and the transfer to the two photosystems in the hormogonia were more effective than in the mature colonies. It may be concluded that the formation of hormogonia affected on the structure and function of phytosynthesis.