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31.
The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.Abbreviations HSMPs heat shock mannoproteins - MAb monoclonal antibody - sIgA secretory IgA  相似文献   
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We have designed a new method for the recovery of T-DNA flanking sequences from T-DNA-tagged lines ofArabidopsis thaliana. Since most transformation vectors in use contain a plant-selectable marker for kanamycin resistance, we can use the 3′ part of thenptII coding region from the T-DNA to complement the bacterial 5′ region of thenptII gene from Tn5 to reconstruct a functional kanamycin-resistance gene inEscherichia coli. We have constructed a vector that contains the 5′ part of thenptII gene from Tn5 up to the uniquePst I site. By cloning total DNA from transformed lines in this vector, we were able to select directly for clones containing a T-DNA fragment, which reconstitutes a functional kanamycin gene, and a fragment of arabidopsis genomic DNA adjacent to the insertion. Flanking sequences up to 4 kb were rescued by this system.  相似文献   
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The temperature dependence of high voltage activated Ca2+ channels has been investigated in cultured dorsal root ganglion neurones from chick embryos, using the cell-attached patch-clamp technique. The dihydropyridine sensitive L-type Ca2+ channel had a conductance of 23 pS, with 110 mM Ba2+ as charge carrier and in the presence of 3 M Bay K 8644. When the temperature was raised from 15 to 30 °C, the unitary channel current amplitude increased, with Q10 value equal to 1.4. The rising phase of the averaged single-channel current became faster, with Q10 value 2.7, whereas the decay phase showed a lower temperature sensitivity. Channel open probability decreased according to an exponential distribution of open and closed times. A second type of Ca2+ channel was identified, which was DHP-insensitive and had a lower conductance with a mean value equal to 13 pS. For the current amplitude, the Q10 value was 1.3. Both activation and inactivation kinetics were strongly accelerated by an increase in temperature. The corresponding time constants gave Q10 values equal to 5.9 for activation, and 2.0 for inactivation. Peak channel open probability was highly sensitive to a change in temperature, with a Q10 value of 1.6. Finally, in -conotoxin GVIA pre-treated neurones, a non-inactivating DHP-insensitive Ca2+ channel with the lowest unitary conductance (10 pS) and a much lower temperature dependence was recorded. Single-channel current was increased by heating, with Q10 value 1.3, whereas the channel kinetics were almost unaffected by temperature. Our data are consistent with the assumption that the different temperature dependence of the Ca2+ channel behaviours may be explained by separate gating processes of three types of Ca2+ channels.  相似文献   
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Testicular weight and DNA content were markedly reduced (63 and 69%) in weanling Long-Evans rat pups rendered hypothyroid from birth by administration of propylthiouracil (PTU), a reversible goitrogen. These growth deficits worsened to >80% by continuing hypothyroidism beyond weaning, to days 50 and 90. Recovery of thyroid function, brought about by discontinuing PTU at weaning, resulted in a paradoxical stimulation of testis growth, amounting to increased weight (40%), DNA content (60%) and size by 90 days, compared to age-matched controls. In the 25-day or older hypothyroid rats, testicular structure was immature and spermatogenesis markedly delayed, as evident by closed lumen and significantly reduced diameter of seminiferous tubules (38%), thickness of germinal layer (70%), and number of primary spermatocytes (86%), compared to control. Hypothyroidism did not alter the number of tubules per testis cross section. In the 90-day recovery rats, numbers of seminiferous tubules were unchanged but tubular diameter was significantly (20%) larger than in controls and spermatogenesis appeared very active as indicated by significantly increased germinal layer thickness (22%) and total number and density of primary spermatocytes (55% and 40%). The results show that although postnatal hypothyroidism is deleterious for testicular growth and spermatogenesis, recovery from this condition leads to enhanced seminiferous tubular growth and spermatogenesis.  相似文献   
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During the establishment of vesicular-arbuscular mycorrhizas, fungal hyphae contact the root surface, form appressoria and initiate the internal colonization phase. Structural changes occur in the cell wall, the cytoplasm and the nucleus as the fungus progresses from a presymbiotic to a symbiotic phase. Nuclei in spores are in G1 whereas in intraradical hyphae they are in G1 and G2. Changes in nuclear organization are evident in various stages in the colonization process. Dramatic changes in both symbionts occur as the nutrient exchange interface is established between arbuscules and root cortical cells. An interfacial matrix, consisting of molecules common to the primary wall of the cortical cell, separates the cortical cell plasma membrane from the fungal cell wall. Ectomycorrhizas are characterized structurally by the presence of a mantle of fungal hyphae enclosing the root and usually an Hartig net of intercellular hyphae characterized by labyrinthine branching. As hyphae contact the root surface, they may respond by increasing their diameter and switching from apical growth to precocious branching. The site of initial contact of hyphae may be either the root cap or the ‘mycorrhiza infection zone’. The mantle varies considerably in structure depending on both the plant and fungus genome. In some ectomycorrhizas, the mantle may be a barrier to apoplastic transport, and in most it may store polyphosphate, glycogen, lipids and perhaps protein.  相似文献   
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Summary Different species of truffle were studied in order to identify species-specific markers. The isolation of two Tuber magnatum Pico markers is reported. One of these could be used as a probe in dot blot hybridization, allowing the development of a rapid test able to identify Tuber magnatum species.  相似文献   
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