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1.
Pollen isolated from cold treated and precultivated anthers of tobacco (Nicotiana tabacum L. var. Wisconsin 38) were separated into different fractions with counter-current distribution using an aqueous Dextran-polyethylene glycol two-phase system. It was possible to distinguish among eight pollen classes differing in developmental stage and in partitioning. A part of each fraction was cultivated for analysis of embryo formation. This was highest in a fraction with an intermediate to high partition in the phase system. Enriched in this fraction were also pollen that were fairly well stained with acetocarmine, contained several nuclei and had a relatively low mitochondrial activity. The enrichment of embryogenic pollen offers several advantages especially to physiological studies on embryogenesis. 相似文献
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Oviducal Contribution to Alteration of the Vitelline Coat in the Frog, Rana japonica. An Electron Microscopic Study 总被引:4,自引:4,他引:0
The vitelline coat (VC) surrounding coelomic eggs of the frog, Rana japonica , comprises bundles of filaments running both parallel and perpendicular to the egg surface. The coat gives little or no staining reaction with PA-CrA-Silver methenamine. In contrast, in the VC of uterine eggs the filament bundles are less conspicuous. and the interstices between the filament bundles stain strongly for carbohydrate. This alteration occurs during passage of the eggs down the first 1/20 th of the oviduct, the pars recta. The epithelium of the p. recta contains secretory cells, which contain electron-dense granules distinct from those in the jelly-secreting cells in more caudal portions of the oviduct. Treatment of coelomic eggs with an extract of p. recta followed by exposure to a sperm suspension resulted in marked swelling and softening of the VC. These results indicate that the contents of the granules secreted from the epithelial cells in the p. recta are deposited in the VC to increase its susceptibility to a fertilizing sperm. 相似文献
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Hormonal Regulation of Pedicel Abscission in Begonia Flower Buds 总被引:1,自引:0,他引:1
CH. H. HÄNISCH TEN CATE J. BERGHOEF A. M. H. VAN DER HOORN J. BRUINSMA 《Physiologia plantarum》1975,33(4):280-284
In order to analyse the hormonal regulation of flower bud shedding in Begonia, levels of indoleacetic acid (IAA), abscisic acid (ABA) and ethylene were determined in buds and pedicels. The translocation and metabolism of 14C-labeled IAA in pedicel segments were also studied. In a monoecious Begonia fuchsioides hybrid, abscising male flower buds contain about 1% of the IAA present in non-abscising female flowers. In a male Begonia davisii hybrid, the seasonal variation in bud drop coincides with changes in the IAA content of the buds, while also the release of IAA from the bud to the pedicel is hampered. Abscission zones of these pedicels always contain abscission promoting ethylene concentrations. The tissue is prevented from responding with abscission by IAA from the flower buds. The buds also contain ABA but without influencing abscission considerably. Pretreatment with ethylene or ABA does not affect IAA transport in pedicel segments. The rate of this transport is 4–6 mm × h–1:; the capacity increases with the transverse area. In young segments, IAA is decarboxylated and also otherwise metabolized. 相似文献
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Hildur Helgadottir Emilia Andersson Lisa Villabona Lena Kanter Henk van der Zanden Geert W. Haasnoot Barbara Seliger Kjell Bergfeldt Johan Hansson Boel Ragnarsson-Olding Rolf Kiessling Giuseppe Valentino Masucci 《Cancer immunology, immunotherapy : CII》2009,58(10):1599-1608
Purpose We have previously demonstrated an association of the human leukocyte antigen (HLA), HLA-A2 allele with ovarian and prostate
cancer mortality as well as a segregation of the ancestral HLA haplotype (AHH) 62.1 [(A2) B15 Cw3 DRB1*04] in patients with
stage III–IV serous ovarian cancer. The objective of the present study was to determine the role of the HLA phenotype on the
prognosis in stage III–IV malignant melanoma patients.
Patients and methods A cohort of metastatic malignant melanoma patients (n = 91), in stage III (n = 26) or IV (n = 65) were analysed for HLA-A, -B, -Cw and -DRB1 types by PCR/sequence-specific primer method. The frequencies of HLA alleles
in the patients were compared to that of healthy Swedish bone marrow donors. The effect of HLA types on prognosis was defined
by Kaplan–Meier and Cox analysis.
Results The presence of the AHH 62.1 in clinical stage IV patients was significantly and independently associated with the worst survival
rate recorded from the appearance of metastasis (HR = 2.14; CI = 1.02–4.4; P = 0.04). In contrast, the period from the primary diagnosis to metastasis was the longest in patients with this haplotype
(HR = 0.40; CI = 0.17–0.90; P = 0.02).
Conclusions Melanoma patients in our cohort with 62.1 AHH which is associated with autoimmune diseases have an initial strong anti-tumour
control with longer metastasis-free period. These patients have rapid progression after the appearance of metastasis, responding
poorly to chemo- or/and immunotherapy. This apparently paradoxical clinical process could be due to the interplay between
tumour clones escape and immune surveillance ending up with a rapid disease progression.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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A new method for computerized modification of sound signals is presented. With digital signal processing in the time domain it is possible to alter the amplitude, the frequency and the time scale of natural sounds independently. The method can be applied to natural sounds with reasonably pure tonal quality. 相似文献
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Verena I. Carrara Khin Maung Lwin Aung Pyae Phyo Elizabeth Ashley Jacher Wiladphaingern Kanlaya Sriprawat Marcus Rijken Machteld Boel Rose McGready Stephane Proux Cindy Chu Pratap Singhasivanon Nicholas White Fran?ois Nosten 《PLoS medicine》2013,10(3)