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Biomedical subjects

J C Gamble

Publications and source records attributed to J C Gamble.

4 recordsLinked to original sources
PubMed1985

Fatty acid composition of phospholipids and neutral lipids during embryonic and early larval development in Atlantic herring (Clupea harengus, L.).

The fatty acid compositions of total polar and total neutral lipids of Atlantic herring eggs and larvae were determined immediately before fertilization, after fertilization and at various times during subsequent embryonic and early larval development. Within 3 hr after fertilization the percentage of total PUFA in neutral lipid decreased from 33% to 20%, with a reciprocal increase in monoenes. Thereafter the percentage of PUFA in the neutral lipids increased progressively, attaining the original level in ripe eggs by the time of yolk sac absorption. During the larval stages the percentage of PUFA continued to increase in the neutral lipid, reaching almost 44% of the total by day 32 after fertilization, although it was reduced to 32% by day 36. The percentage of monoenes in the neutral lipid displayed a progressive decrease during the whole period of development from 3 hr after fertilization. Throughout all the developmental periods the fatty acid composition of total polar lipids remained essentially constant. The polar lipids of the yolk sac displayed virtually the same fatty acid composition as the larval bodies, but the neutral lipids of the yolk sac were low in PUFA compared to the larval bodies. The results are discussed with reference to changes in lipid class composition during development. The conservation of high levels of PUFA in lipids during embryogenesis and early larval development reflects the importance of these fatty acids during development.

Animals↗
PubMed1985

Lipid class composition during embryonic and early larval development in Atlantic herring (Clupea harengus, L.).

The lipid class compositions of Atlantic herring eggs and larvae were determined immediately before fertilization, after fertilization and at various times during subsequent embryonic and early larval development. Total lipid constituted 15% of the dry wt of ripe eggs, 70% of the total lipid being polar lipid with phosphatidylcholine (PC) accounting for almost 90% of the polar lipid. In general, the total lipid content decreased gradually during embryogenesis and in particular during larval development. Within 3 hr after fertilization the relative percentage of neutral lipid decreased slightly. This was followed by a general decrease in polar lipid which, by the stage of yolk sac absorption, was reduced to 52% of the total lipid. The decreased percentage of polar lipid was due entirely to a decrease in PC, which was reduced to 66% of the polar lipids at the stage of yolk sac absorption. The accompanying increase in the percentage of neutral lipids was mainly due to increased percentages of triacylglycerols (TAG) up to yolk sac absorption and cholesterol esters in the larval stages. During the first 4 days after hatching, phospholipids and to a lesser extent cholesterol were preferentially depleted in the yolk sacs, which also had higher levels of free fatty acids. The results are discussed in relation to possible roles of different lipids during embryonic and early larval development.

Animals↗
PubMed1979

Experiments with large enclosed ecosystems.

Three of the major advantages of enclosure experiments are that they ensure (1) that the same populations are sampled over a long period; (2) that populations of at least three trophic levels are initially enclosed in naturally occurring proportions and that they are self sustaining over a long experimental period; and (3) that replicate enclosed populations can be experimentally manipulated. There are two disadvantages which must be mentioned. These are (1) that vertical mixing, which may be reduced by as much as an order of magnitude compared to the open sea, will undoubtedly affect the sinking rates of phytoplankton and may influence the structure of the population; and (2) that as a general rule the larger and therefore more expensive the enclosures become, the more difficult it is to run sufficient replicates. An experiment is described in which 1 microgram Hg/l was added to two 95 m3 bags (3 mdiameter by 17 m deep) and the response of the pelagic population monitored over the following 20 days. A further 10 micrograms Hg/l was then added to each enclosure and the response measured for a further 20 days. The results indicated that: (i) inorganic mercury added to the water column is very rapidly transformed into 'bound' or 'non-reactive' mercury and that about 25% of the mercury added was recovered associated with the organic material settling to the bottom of the bags; (ii) the response of the biological population to 1 microgram Hg/l was very limited and in fact a transient reduction in photosynthetic carbon uptake per unit chlorophyll was the only noticeable effect and there were no changes in population size or structure that could be attributed to mercury; (iii) at 10 micrograms Hg/l the zooplankton population was reduced markedly and this did produce changes in the structure of both the zooplankton and phytoplankton populations. These results are similar to the results of a comparable experiment carried out in Vancouver Island (Cepex) and point to the conclusion that the levels of mercury found in surface waters around the coast of the U.K. (0.001--0.022 microgram Hg/l) are one or two orders of magnitude below the levels at which a response of the biological population can be demonstrated. The usefulness of large scale enclosed ecosystems for further pollution research is discussed and it is concluded that those facilities that provided a link between the water column and the sediments would be most useful since they would (1) enable estimates to be made of the flux rates of pollutants from the water column to the sediments; and (2) allow experiments to be carried out with the pollutant in contact with sediment in its natural form.

Bacterial Physiological Phenomena↗