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JOHNSTONE O. YOUNG 《Freshwater Biology》1972,2(4):355-359
Five new British records of freshwater Microturbellaria are illustrated: Gieysztoria infundibuliformis, Castrada lanceola, Castrada neocomensis, Castrada viridis and Strongylostoma elongatum. These species together with a new species, Macrostomum johni described by Young (1972), are woven into the fabric of the existing key for the group (Young, 1970). All six species were recorded from the littoral zone of lakes in Caernarvonshire, N. Wales. The times of the recordings are indicated. 相似文献
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JEONG-WEON KIM MIKE F. SLAVIK 《Journal of Rapid Methods and Automation in Microbiology》1996,4(3):183-190
Blue Lake, an insoluble dye, was evaluated as an indicator of potential bacterial penetration into eggs. Various groups of eggs (fresh-laid; commercial; water-washed) were dipped in 0.25% (w/v) Blue Lake in 0.1% Triton X-100 solution for 2 min and incubated at room temperature up to 1 ± 24 h. Penetration was detected by counting the blue dots on shell membranes after breaking the eggs. Commercial eggs allowed the easiest penetration. All commercial eggs showed blue dots even at 2 min incubation and the average count reached 111/egg at 1 h. Water-washed eggs allowed much less penetration than commercial eggs and the counts of blue dots on those eggs were 10/egg at 2 min and 22 at 1 h. Fresh-laid eggs did not allow any penetration up to 24 h. Above results corresponded very well with the penetration study with Salmonella enteritidis and also with the morphological study of eggshell surfaces using electron microscopy where fresh-laid eggs had intact cuticle layers, but commercial eggs did not. Thus, Blue Lake dye might be used as a rapid indicator of bacterial penetration through eggshells. 相似文献
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Measuring the effect of observations on Bayes factors 总被引:2,自引:0,他引:2
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Sexual swarms in Daphnia magna, a cyclic parthenogen 总被引:3,自引:0,他引:3
J. P. W. YOUNG 《Freshwater Biology》1978,8(3):279-281
SUMMARY. Dense swarms were observed in a population of Daphnia magna (Crustacea: Cladocera). The swarms appeared during a sexual period in which females were abundant but males were rare. Each swarm contained several males and large numbers of 'imminently sexual' females, a class of females that was rare except in the swarms. This implies that both sexes respond to attractant stimuli, and that the female response occurs only during a brief critical phase in the ovarian cycle. 相似文献
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C. A. WATKINS R. J. McNICOL K. YOUNG A. T. JONES † 《The Annals of applied biology》1990,116(3):489-492
Because there is some evidence that June Yellows (JY) of strawberry may be caused by a pathogenic agent, combinations of heat treatment and meristem-tip culture that are known to eliminate some viruses from tissues were used in attempts to cure affected Cambridge Favourite strawberry plants from JY. None of 397 propagants derived from JY-affected plants subjected to various combinations of these treatments were freed from JY. Indeed, all propagants showed more obvious JY symptoms than the parent plants from which they were derived, suggesting that such treatments may be useful for detecting incipient JY in symptomless strawberry stocks. 相似文献
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A technique is described to accurately assess the dermal contactdose-mortality response of molluscicides. The technique involvescarbon dioxide anaesthesia of laboratory reared Deroceras reticulatum(Müller) followed by application of test substances insolution to the dorsal surface. The LD50 of the substances testedwere as follows: Sodium pentachlorophenate, 55.9 ng.mg1,Copper sulphate, 124.1 ng.mg1, Methiocarb, 314.6 ng.mg1and Potassium permanganate, 418.9 ng.mg1 body weight. (Received 18 August 1988; accepted 17 December 1988) 相似文献