Fish-bone oil: Percent total body lipid and carbon-14 uptake following feeding of 1-14C-palmitic acid

Bones contain the majority of body lipid in some marine fish. In the sheepshead wrasse Pimelometopon pulchrum and the sablefish Anoplopoma fimbria, the bone lipid comprised 79 to 93% and 52 to 82% of the total body lipid, respectively. The senorita Oxyjulus california, another species of wrasse, has only 14% of its body lipid in bone. To determine whether dietary lipid is deposited quickly in the bone lipid, three species of fish were fed 1-¹⁴C-palmitic acid. Radioactivity appeared in the bone lipid as soon as 12 h after feeding, with the species rich in bone lipid incorporating the highest activity relative to the flesh. Roughly 80% of the radioactivity recovered in A. fimbria bone lipid was found in triglyceride. Radioactivity was equally distributed between phospholipid and triglyceride in P. pulchrum bone lipids. The results suggest that in some marine fish the bones contain the majority of the organism's reserve energy.     

Glycerol translocation in Condylactis gigantea

Sodium cyanide (NaCN) was used to partially uncouple respiration and photosynthesis in the symbiotic sea anemone Condylactis gigantea. NaCN significantly increased the ratio of gross photosynthesis to respiration in both intact tentacles and isolated zooxanthellae (Symbiodinium microadriaticum), increased carbon translocation from 17.7±3.5% of total fixed in controls to 43.5±5.8%, and doubled the amount of photosynthetically fixed carbon accumulating in the coelenterate host over that in controls. Only 2% of the non-particulate radioactivity recovered in the host tissue was ¹⁴C-glycerol when uninhibited symbiotic tentacles were incubated in ¹⁴C-bicarbonate for 1 h. At 10^-5 M NaCN, approximately 25% of the host nonparticulate radioactivity was recovered as ¹⁴C-glycerol, the absolute concentration of glycerol in the host tissue was three times higher than in controls, and ¹⁴C-glycerol was found in the medium. While glycerol has been proposed to play a major role in the translocation of photosynthetically fixed carbon from zooxanthellae to their coelenterate hosts, its concentration has never been measured in the animal and algal components of the symbiosis. The isolated zooxanthellae contained 3.62±0.33 mM glycerol, 26x the 0.141±0.02 mM found in the anemone. Aposymbiotic anemone tissue contained 0.169±0.06 mM glycerol. The rate of glycerol mineralization was not saturated even when exogenous glycerol levels were 70x internal concentrations. These data show that respiration and photosynthesis in symbiotic associations may be partially uncoupled by NaCN, and that this uncoupling allows the verification of the translocation and rapid catabolism of glycerol within the host.     

Towards resolving the phosphorus chaos created by food systems

Ambio - The chaotic distribution and dispersal of phosphorus (P) used in food systems (defined here as disorderly disruptions to the P cycle) is harming our environment beyond acceptable limits. An...     

Evaluation of Early Life Stage Fall Chinook Salmon Exposed to Hexavalent Chromium from a Contaminated Groundwater Source

We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon (Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival, development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium. Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures (i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 μg/l. Survival for all treatment levels and controls exceeded 98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations. Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater–river water interface, the current cleanup criterion of 10 μg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings, together with previous research indicate low risk to these populations.     

Lipogenesis in the intact coral Pocillopora capitata and its isolated zooxanthellae: Evidence for a light-driven carbon cycle between symbiont and host

Surface tissue of the reef coral Pocillopora capitata contained approximately 34% lipid on a dry weight basis. Of this, 75% was storage lipid (wax ester and triglyceride) and 25% structural (phospholipid, galactolipid, etc.). Based on chlorophyll a: lipid ratios of intact coral and isolated zooxanthellae, it was determined that over 90% of the storage lipid resided in the host tissue. One half of the structural lipids was found in the host and the other in the symbiotic algae. Gentle fractionation of coral tissue indicated that zooxanthellae possessed less than 14% of the total coral protein. Coral tips and isolated zooxanthellae were incubated with sodium acetate-1-¹⁴C in light and dark to obtain lipogenic rates and proportions of fatty acids and lipid classes synthesized. The rate of lipid synthesis from acetate-1-¹⁴C by intact coral was stimulated three-fold in the light (1200 lux), which indicated that the majority of coral lipogenesis occurred in the zooxanthellae. Intact coral triglycerides contained ca. 68% of the ¹⁴C-activity and wax esters ca. 21%. Zooxanthellae isolated by the Water Pik technique synthesized negligible amounts of wax ester, which implied that wax ester synthesis was a property of the animal tissue. Isolated zooxanthellae and intact coral synthesized identical triglyceride fatty acids from acetate-1-¹⁴C. This study provides evidence for a carbon cycle between host and symbiont whereby the zooxanthellae take up host-derived carbon (probably in the form of acetate), synthesize fatty acids using their photosynthetically derived energy, and return the lipid to the host where it appears as wax ester and triglyceride.