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Several leafhopper variants of the Circulifer tenellus complex were collected in “citrus stubborn” affected areas in Israel. Two of these variants transmitted the Spiroplasma citri to Matthiola incana after being injected with the disease agent. The variant from Atriplex halimus was designated Circulifer tenellus-A (CTA) and the variant from Portulaca oleracea was designated Circulifer tenellus-? (CTP). Transmission characteristics were determined for both leafhoppers. A high rate of transmission (43.3%) was obtained by single CTA leafhoppers that were injected with the Amiad S. citri isolate from the Upper Galilee, compared with 7% transmission obtained with the CTP leafhoppers. The Gilgal S. citri isolate from the Jordan Valley, was not transmitted by either. Injection was more effective than acquisition access feeding to render the leafhopper infective for both CTA and CTP. The minimum acquisition access period needed for the CTA variant to transmit the Amiad isolate was 1 h. Longer AAPs did not necessarily result in a higher rate of transmission. The minimum incubation period was 6 days and the maximum was 32 days. The LP50 calculated from the logarithmic curve y = 45.74Ln(x)–53.68 was 9.64 days. The minimum inoculation access period (IAP) was lh. The same transmission parameters for the CTP variant could not be determined, as no transmission was obtained even when groups of five-six insects were placed on a single plant. 相似文献
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The weevil Rhinocyllu conicus develops only in the flowerheads of thistles {Asteracea; Carduineae) and therefore it is used as a biocontrol agent against thistle weed species. Populations out of 14 regions within its natural distribution area (from the Atlantic coast in the west to Israel in the east) were analysed by means of allozymes and morphometries. In both analyses the 14 populations were grouped into two concordant units. Based on nine scored loci (six of them polymorphic), mean Nei's genetic distance between the two groups was 0.073. In a reclassification test following DFA of morphometric data, 93.2% of all individuals were grouped back into the correct group. The two groups were considered to belong to a temperate and a Mediterranean subspecies respectively, the latter probably identical to the formerly described Rhinocyllus oblongus . 相似文献
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Multidimensional scaling (MDS) procedures produce maps of stimulus points, the dimensions of which may be sensory and/or physicochemical attributes. Our objective was to test the efficiencies of a cyclic design and a MDS method in the study of saltiness perception. Two levels of NaCl (0.1% and 0.2%, w/v) were added to two nonionic and two ionic gum solutions prepared to two concentrations. Subjects scaled dissimilarities between pairs of solutions and rated each sample for flavor attributes. Solution pairs were selected using cyclic designs. Repeated measures ANOVA determined that added NaCl was the only significant factor affecting saltiness perception. In contrast, from KYST-2A MDS maps, we concluded that saltiness perception was influenced by gum property, gum concentration, presence of calcium and potassium, and related to binding of the sodium ion (Na+ ) as determined by 23 Na nuclear magnetic resonance (NMR) spectroscopy. The MDS cyclic design successfully reduced the number of samples and subjects when using experienced subjects. 相似文献
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Free and total putrescine and, to a lesser extent, spemidine accumulate in both roots and shoots of peas in response to potas stum deficiency and ammomnium supply. Free putrescine responds more sensitively than total putreseine to variatioin of nutrients. Accumulation of putrescine is more pronounced in the roots than in the shoots. 相似文献
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SALLY LYMAN ALLEN JULIAN ADAMS CAROLINE L. RUSHFORD 《The Journal of eukaryotic microbiology》1983,30(1):143-147
ABSTRACT. Up to five zones of acid phosphatase activity appear in gels after electrophoresis of detergent-treated extracts from 13 of the 14 species of the Paramecium aurelia complex. The overall pattern is somewhat similar for all species: differences in intensity and mobility of individual zones permit the grouping of these sibling species into eight groups. All 14 species can be identified using the procedure of enzyme electrophoresis, although two of them are more similar than is usually the case. Problems of misclassification are discussed in terms of the nature and frequency of variants. With the judicious choice of enzymes used to screen new stocks, these problems can be circumvented. Species relationships are updated using 11 enzymes. A dendrogram constructed from the matrix of genetic distances shows four clusters of species: (i) P. biaurelia, P. triaurelia; (ii) P. primaurelia, P. pentaurelia, P. sexaurelia, P. novaurelia; (iii) P. septaurelia, P. undecaurelia, P. tredecaurelia, P. quadecaurelia; and (iv) P. tetraurelia, P. octaurelia, P. decaurelia, P. dodecaurelia. Distances between the species are large, on the order of the differences between Drosophila species. The species are characterized by an extraordinary lack of geographical differentiation and great morphological similarity, which contrasts strongly with the molecular differentiation. 相似文献