Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.788500
Title: Carbon metabolism in the Anemonia viridis symbiosis
Author: Harland, Anthony D.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1992
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Abstract:
This study was undertaken to investigate some aspects of carbon metabolism in the temperate symbiotic sea anemone Anemonia viridis (Forskal). In particular, questions were asked about the nutritional interactions between the algal symbionts and host, and how these affect the lipid stores. Further questions addressed the quantitative importance of the carbon which is fixed in photosynthesis and translocated to the host. Are anemones potentially autotrophic with respect to carbon? Anemonia viridis contained about 11% lipid on a dry weight basis when maintained at light levels of about 10μE m⁻² s⁻¹ and a temperature of 10°C. Aposymbiotic forms of the anemone had similar lipid levels. These values are very low when compared with tropical symbiotic anthozoa in which lipid levels are up to 50% of dry weight. In symbiotic A. viridis, less than 6% of total lipid consisted of the storage lipids, wax esters and triglycerides. Most of the triglyceride was stored in the animal tissues rather than the zooxanthellae. Zooxanthellae contained only small amounts of wax esters. An analysis was made of the triglyceride, wax ester and fatty acid composition of symbiotic anemones, isolated zooxanthellae and aposymbiotic anemones. Wax ester composition was similar in symbiotic and aposymbiotic forms. However, triglyceride composition differed. In particular trimyristin (C42) was found only within the symbiotic association. Fatty acids showed a high degree of unsaturation, and acids with both odd and even numbers of carbon atoms were found. The most abundant fatty acid was 16:0 in all samples except for the total lipids from zooxanthellae in which the major fatty acid was trans 18:1. In order to examine the effect of light level on the total and storage lipids, anemones were exposed to three experimental light regimes of 10, 100 and 300 μE m⁻² s⁻¹. Anemones were fed once a week. After 30 days there were no significant differences in the total lipid levels between anemones at any of the light intensities. However, after 60 days lipids had increased in proportion to light level in both the zooxanthellae and animal tissue compartments. The higher levels of total lipid were in part due to increases in storage lipid (wax esters and triglycerides). Wax ester levels increased in the animal tissues but remained constant in the zooxanthellae whereas triglycerides increased in both compartments. In contrast to fed anemones, starved anemones which were maintained at 300 μE m⁻² s⁻¹ for 30 or 60 days did not show a statistically significant change in lipid levels at 60 days. However, there was a significant increase in the storage lipids which suggested that the non-storage phospholipids and structural lipids had declined as a result of cellular catabolism. The composition of the wax esters and triglycerides of both fed and starved anemones was analysed and compositional changes were observed at higher light intensities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.788500  DOI: Not available
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