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11.
P. S. GREWAL P. N. RICHARDSON G. COLLINS R. N. EDMONDSON 《The Annals of applied biology》1992,121(3):511-520
In a mushroom crop (Agaricus bisporus) affected by a very low level of sciarid fly (Lycoriella auripila) infestation, the effects of an indigenous isolate of insect-parasitic nematode (Steinernema feltiae) and of two commonly used insecticides (diazinon and diflubenzuron) were studied. When compared with untreated plots, nematodes applied to the casing had no adverse effects on mushroom yields whereas insecticides decreased yields. At a rate of 3 × 106 infective juveniles per tray (surface area = 0.56 m2), S. feltiae elicited increases of 28.5% and 19% in the mean total numbers and weights of mushrooms respectively. Treatment only with diflubenzuron resulted in 14.6% and 6% reductions in mean total numbers and weights of mushrooms, respectively; treatment with both diazinon and diflubenzuron caused 18.5% and 9.4% losses. Application of nematodes generally reduced the mean weight per mushroom whereas insecticides increased it; nematodes delayed the onset of mushroom production (first flush) whereas diflubenzuron delayed the third and fourth flushes. Nematode contamination of sporophores was minimal when S. feltiae was applied at casing. Although their numbers declined with time, the nematodes persisted, in the casing layer, throughout the cropping period of seven weeks. It is concluded that yield benefits associated with nematode application can result mainly from nematode effects on A. bisporus and not solely from suppression of a damaging pest population. 相似文献
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Melanocytes in human skin reside both in the epidermis and in the matrix and outer root sheath of anagen hair follicles. Comparative study of melanocytes in these different locations has been difficult as hair follicle melanocytes could not be cultured. In this study we used a recently described method of growing hair follicle melanocytes to characterize and compare hair follicle and epidermal melanocytes in the scalp of the same individual. Three morphologically and antigenically distinct types of melanocytes were observed in primary culture. These included (1) moderately pigmented and polydendritic melanocytes derived from epidermis; (2) small, bipolar, amelanotic melanocytes; and (3) large, intensely pigmented melanocytes; the latter two were derived from hair follicles. The three sub-populations of cells all reacted with melanocyte-specific monoclonal antibody. Epidermal and amelanotic hair follicle melanocytes proliferated well in culture, whereas the intensely pigmented hair follicle melanocytes did not. Amelanotic hair follicle melanocytes differed from epidermal melanocytes in being less differentiated, and they expressed less mature melanosome antigens. In addition, hair follicle melanocytes expressed some antigens associated with alopecia areata, but not antigens associated with vitiligo, whereas the reverse was true for epidermal melanocytes. Thus, antigenically different populations of melanocytes are present in epidermis and hair follicle. This could account for the preferential destruction of hair follicle melanocytes in alopecia areata and of epidermal melanocytes in vitiligo. 相似文献
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In general, the brown honeyeater, Lichmera indistincta, flies more and expends more energy when visiting flowers in the early morning than at other times. Floral nectar is most abundant early in the day, and nectar energy intake by L. indistincta is greatest at that time. It appears as if birds can only store excess energy during the early part of the day, incurring energy deficits at other times. Unit perching and flight costs are greatest for L. indistincta in winter and spring. As a result, peak total energy expenditures and requirements occur at these times, birds apparently being unable to reduce energy demands by employing nocturnal torpor. Estimates of probable energy uptake by L. indistincta from the plant species studied exceed predicted requirements in all seasons except winter, when it is apparent that birds would need to be especially selective in the plants that they used as major energy sources. 相似文献
14.
The Effects of Salinity upon Galactosyl-Glycerol Content and Concentration of the Marine Red Alga Porphyra purpurea (Roth) C.Ag. 总被引:2,自引:0,他引:2
REED ROBERT H.; COLLINS JULIAN C.; RUSSELL GEORGE 《Journal of experimental botany》1980,31(6):1539-1554
Changes in the major alcohol-soluble, low molecular weight carbohydratesof P. purpurea, O--D-galactopyranosyl-(1-2)-glycerol (floridoside)and O--D-galactopyranosyl-(1-1)-glycerol (isofloridoside),have been examined in response to salinity variation. Floridosideis shown to vary in absolute amount, increasing in hypersalineand decreasing in hyposaline media. Isofloridosidecontent per cell does not change in a similar manner. Responsesare almost identical under light or dark conditions, floridosidechanges being complete within 24 h. Decreasing the externalwater potential using ionic and non-ionic solutes has the sameeffect upon galactosyl-glycerol content. The amount of floridosidesynthesized, and degraded under hypersaline and hyposaline conditionsrespectively is shown to be insufficient to restore cell volumeto its original value. It is therefore suggested that the primaryfunction of floridoside increases in concentratedsea-waters is that of a compatible solute, serving to protectthe cell during periods when the external salt content is increaseddramatically. 相似文献
15.
Isoprenoid Quinone Composition as a Guide to the Classification of Sporolactobacillus and Possibly Related Bacteria 总被引:1,自引:1,他引:0
Menaquinones with seven isoprene units were the major isoprenoid quinones detected in the chloroform-methanol extracts of representative strains of the genera Bacillus and Sporolactobacillus. Neither menaquinones nor ubiquinones were detected in similar extracts of strains of the genus Lactobacillus. 相似文献
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The excision of cotyledons from two cultivars of peas soon aftergermination resulted in a lowering of the node of first floweringas well as a delay in both flower initiation and flowering,especially in the late cultivar Greenfeast. This is contraryto the usual view that, when cotyledon excision reduces nodeof first flowering, flower initiation and flowering are hastened,and it seems irreconcilable with the colysanthin theory of Barber(1959). An alternative explanation is proposed. 相似文献
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