Physiological and biochemical studies of Laurencia spectabilis and its symbiont Janczewskia gardneri (Ceramiales, Rhodophyceae)

• Main Author: Court, Gary James
• Language: English
• Published: 2010
• Online Access: http://hdl.handle.net/2429/21499

This thesis is a two part study on the biochemistry and physiology of the red algae Janczewskia gardneri Setchell & Guernsey and Laurencia spectabilis Postels & Ruprecht (Ceramiales, Rhodophyceae). The first part consists of photosynthesis, translocatory, microscopic, and cultural studies of the symbiotic association between the supposed parasite J. gardneri and its host L. spectabilis. Mature plants of J. gardneri were pigmented, contained typical red algal chloroplasts when viewed by electron microscopy, and were capable of photosynthesis. Both J. gardneri and L. spectabilis incorporated ¹⁴C-label from NaH¹⁴CO₃ into similar compounds, including sugars (floridoside, isofloridoside, galactose, glucose) and amino acids (alanine, aspartic acid, glutamic acid, glycine, serine). Translocation of ¹⁴C-labeled photosynthetic products between mature J. gardneri and its host did not occur. Released spores of J. gardneri were pigmented, contained mitochondria, proplastids and floridean starch reserves, and germinated in the absence of the host; however, the germlings died within two weeks. This research suggested that mature individuals of J. gardneri were obligate epiphytes. The second part of this thesis reports on the isolation and partial characterization of a proteoglycan from L. spectabilis. The proteoglycan was isolated by extraction in a dilute buffer-NaCl solution followed by gel and ion exchange chromatography, using cellulose acetate strip electrophoresis for monitoring purification. The non-sulfated proteoglycan contained 92% carbohydrate and 8% protein. Galactose (85%) was the major neutral sugar detected. Uronic acids, glucose, xylose and a trace of arabinose were also present. A small quantity of hydroxyproline was present in the molecule. === Science, Faculty of === Botany, Department of === Unknown