Comparative Studies of Leaf Tissue and Isolated Mesophyll Protoplasts: II. ION RELATIONS

Freshly isolated tobacco mesophyll protoplasts had contentsof K^$, Cl^– and Na^$ slightly higher (on a cell basis) thanthe original leaf tissue, and had a high K^$/Na^$ ratio similarto that of the leaf tissue. Influxes of these ions into theprotoplasts were of similar magnitudes to the correspondingfluxes in leaf tissue when compared on the basis of the respectiveplasmalemma surface areas. In both systems the K^$ influx wasstrongly inhibited by CN^– and by DNP. These results suggestthat the ion relations of the freshly isolated mesophyll protoplastswere similar to those of the original leaf tissue and that isolatedmesophyll protoplasts should be a useful system for the studyof ion transport processes in leaf cells.     

Foraging range and feeding locations of Shags Phalacrocorax aristotelis during chick rearing

We used radio-tracking techniques to determine the foraging range and feeding locations used by individual Shags Phalacrocorax aristotelis during chick rearing on the Isle of May, Scotland. The mean (±s.d.) foraging range was 7.o±1.9 km (maximum 17 km) and there were no significant sex or year differences. All feeding sites were within 7 km of land. Most (> 90%) were either within 2 km of the colony or in two discrete areas 5–13 km to the north and west. Use of the areas varied between years with both males and females making more use of the north area in 1987 than either 1988 or 1989. Birds used > 11% of the area of sea within the maximum recorded feeding range. This restricted distribution appeared to be related to water-depth and bottom sediment type. Shags fed most frequently in water 21–40 m deep, with a bottom of either gravel and sand, or rock with thin patchy sediment cover.     

Endogenous Inhibitors and Germination of Beta vulgaris

The nature and importance of endogenous germination inhibitorsin rubbed triploid monogerm sugar beet fruits were studied.Experimental evidence suggests that germination inhibitors donot play an important role in the prevention of germinationof rubbed fruits. Putative inhibitory compounds known to occurin sugar beet extracts were found to have little effect on germination.Measures to leach out water soluble compounds also had littleeffect on germination. Concentrated fruit extracts were foundto inhibit the germination of sugar beet seeds by virtue oftheir osmotic potentials, and this was related to the salt contentof the fruit extracts. However, a positive relationship wasfound between salt content and the original germination of thefruit lines. This relationship could have important consequencesfor assessment of fruit maturity and subsequent germinationbehaviour at harvest. The causes of poor germination in rubbedfruit lie not in the presence of inhibitory compounds in thefruit coat but in some other property of the fruit. Key words: Germination, Sugar beet: Inhibitors     

Blowfly species composition in sheep myiasis in Scotland

Abstract Samples of dipteran larvae were collected from live sheep throughout Scotland, reared in the laboratory, and identified once adult flies emerged. Lucilia sericata was found in 77% of samples, and other species in 49%. The most common alternative species were L.caesar , which occurred in 31 % of samples, and Protophormia terraenovae , which occurred in 18%. Three other calliphorid species, Calliphora vomitoria, C.vicina and Lillustris , and the muscid Muscina pabulorum were also found. The proportion of samples containing alternative species was significantly lower in eastern Scotland than in western Scotland. Significantly higher proportions of samples containing alternative species were collected at altitudes of 200 m and above; from sheep of hill breeds; from rough grazing conditions and moorland; in the absence of trees; and in the presence of bracken.