Certain plant receptor-like cytoplasmic kinases were reported to interact with small monomeric G-proteins of the RHO of plant (ROP; also called RAC) family in planta and to be activated by this ...interaction in vitro. We identified a barley (Hordeum vulgare) partial cDNA of a ROP binding protein kinase (HvRBK1) in yeast (Saccharomyces cerevisiae) two-hybrid screenings with barley HvROP bait proteins. Protein interaction of the constitutively activated (CA) barley HvROPs CA HvRACB and CA HvRAC1 with full-length HvRBK1 was verified in yeast and in planta. Green fluorescent protein-tagged HvRBK1 appears in the cytoplasm and nucleoplasm, but CA HvRACB or CA HvRAC1 can recruit green fluorescent protein-HvRBK1 to the cell periphery. Barley HvRBK1 is an active kinase in vitro, and activity is enhanced by CA HvRACB or GTP-loaded HvRAC1. Hence, HvRBK1 might act downstream of active HvROPs. Transient-induced gene silencing of barley HvRBK1 supported penetration by the parasitic fungus Blumeria graminis f. sp. hordei, suggesting a function of the protein in basal disease resistance. Transient knockdown of HvRBK1 also influenced the stability of cortical microtubules in barley epidermal cells. Hence, HvRBK1 might function in basal resistance to powdery mildew by influencing microtubule organization.
Non‐host resistance is the resistance of plants against all so‐called non‐adapted pathogens, and is considered the most durable and efficient immune system of plants. We investigated barley powdery ...mildew (Blumeria graminis f.sp. hordei, Bgh)‐triggered defence responses in seven wheat genotypes, and the induction of resistance by this non‐host pathogen to challenge infection with leaf rust, Puccinia triticina Eriks (formerly known as Puccinia recondita f.sp. tritici). Bright‐field and ultraviolet microscopy revealed that although the germination of conidia on non‐host wheat leaves was generally lower than on host barley leaves, the 100% germination on Mv Mambó and only 50% germination on Mv 1 wheat genotypes are the two extremes. If we consider only the germinated conidia, papilla formation was the most frequently observed interaction on Mv 2 (90%) and Mv 4 (88%) genotypes. Epidermal cell death was pronounced on Mv Mambó (31%), but rare on Mv 2 (10%) and Mv 4 (11%), and a mesophyll hypersensitive response could even be detected. At sites of penetration attempts accumulation of H2O2 was shown by 3,3′‐diaminobenzidine staining. Ascorbate peroxidase, glutathione S‐transferase and catalase enzyme activities were augmented by 24.5%, 40.4%, and 21.5%, respectively, in wheat leaves 2 days after Bgh infection. Primary inoculation with Bgh, although with high variability, reduced the number of pustules in all wheat genotypes at first and third leaf stages upon inoculation with leaf rust races 12 and 61 by 10%–70% depending on the genotype, leaf stage and rust race.
Summary
RHO‐like GTPases of plants (ROPs, also called RACs) are involved in plant development and interaction with the environment. The barley ROP protein RACB is involved in susceptibility to the ...fungal pathogen Blumeria graminis f.sp. hordei (Bgh). By screening barley sequence databases for potential protein interactors of plant RHO‐like proteins, we identified a ROP‐interactive CRIB (CDC42/RAC interactive binding) motif containing protein of 171 amino acids (RIC171). The protein interacted with constitutively activated RACB in a targeted yeast two‐hybrid assay. By use of split yellow fluorescing protein fusions, we demonstrated that RIC171 interacts with constitutively activated (CA) RACB‐G15V but not with dominant negative RACB‐T20N in planta. Transient overexpression of RIC171, similar to overexpression of CA RACB‐G15V, rendered epidermal cells more susceptible to penetration by Bgh. In contrast, expression of a 46‐amino‐acid RIC171‐CRIB peptide, which was sufficient to interact with CA RACB‐G15V, had a dominant negative effect and reduced susceptibility to Bgh. A red fluorescing DsRED–RIC171 fusion protein colocalized with green fluorescing GFP–RACB‐G15V at the cell periphery. Coexpression with CA RACB‐G15V but not with RACB‐T20N increased peripheral localization of DsRED–RIC171. Additionally, DsRED–RIC171 accumulated at sites of fungal attack, suggesting enhanced ROP activity at sites of attempted fungal penetration.
Leaves of powdery mildew-susceptible barley (Hordeum vulgare cv. Ingrid) and related near-isogenic lines bearing various resistance genes (Mla12, Mlg or mlo5) were inoculated with Blumeria graminis ...f. sp. hordei race A6. Fungal attack induced several-fold increases in ethylene emission and electrolyte leakage in leaves of susceptible Ingrid beginning 3 days after inoculation. Activities of peroxidase, superoxide dismutase, glutathione S-transferase, ascorbate peroxidase and glutathione reductase enzymes were induced markedly in susceptible leaves 5-7 days after inoculation. Similar, but less pronounced pathogen-induced changes were detected in inoculated leaves of Mla-type resistant plants that show hypersensitive cell death upon inoculation, and, to an even lesser extent, in the Mlg and mlo lines, where no visible symptoms accompanied the incompatible interaction. Glutathione content increased only in susceptible barley 7 days after inoculation. Catalase activity, total ascorbate content and redox state were not influenced by inoculation in any of the genotypes. The activity of dehydroascorbate reductase was significantly reduced 3-5 days after inoculation in the susceptible parental plants and after 5 days in Mla and Mlg lines, while it was stable in the mlo barley. Slightly elevated levels of H₂O₂ were observed in the inoculated resistant plants. In contrast, H₂O₂ content decreased in the susceptible line 7 days after pathogen attack. These data indicate that high levels of antioxidants are involved in the compatible interaction of susceptible barley and powdery mildew by protecting the pathogen from oxidative damage.
Certain plant receptor-like cytoplasmic kinases were reported to interact with small monomeric G-proteins of the RHO of plant (ROP; also called RAC) family in planta and to be activated by this ...interaction in vitro. We identified a barley (Hordeum vulgare) partial cDNA of a ROP binding protein kinase (HvRBK1) in yeast (Saccharomyces cerevisiae) two-hybrid screenings with barley HvROP bait proteins. Protein interaction of the constitutively activated (CA) barley HvROPs CA HvRACB and CA HvRAC1 with full-length HvRBK1 was verified in yeast and in planta. Green fluorescent protein-tagged HvRBK1 appears in the cytoplasm and nucleoplasm, but CA HvRACB or CA HvRAC1 can recruit green fluorescent protein-HvRBK1 to the cell periphery. Barley HvRBK1 is an active kinase in vitro, and activity is enhanced by CA HvRACB or GTP-loaded HvRAC1. Hence, HvRBK1 might act downstream of active HvROPs. Transient-induced gene silencing of barley HvRBK1 supported penetration by the parasitic fungus Blumeria graminis f. sp. hordei, suggesting a function of the protein in basal disease resistance. Transient knockdown of HvRBK1 also influenced the stability of cortical microtubules in barley epidermal cells. Hence, HvRBK1 might function in basal resistance to powdery mildew by influencing microtubule organization.
Eighteen two-year-olds and twenty four-year-olds were studied as to their knowledge and use of eleven colour terms: BLUE,GREEN,RED,YELLOW,BLACK,WHITE,GREY,BROWN,PURPLE, ORANGE, and PINK. Level of ...acquisition was determined by a production (naming) task, a comprehension (selection) task, and a discrimination (matching) task. The objectives were to examine various performance differences in light of possible evolutionary, perceptual and environmental factors and aspects of general lexical development.;
Performance accuracy was found to have no correlations with the evolutionary order proposed by Berlin & Kay, nor did it reveal the strong conceptual groups of primary, non-primary and achromatic colours which have been proposed by other studies. In particular, the non-primary colours did not behave as a group in any of the analyses.;
Measures of input and practice obtained from parental questionnaires also showed few correlations of environment with task performance. For various reasons, this information was considered unreliable and no claims about environment as a determinant in naming behavior could be made.;
Performance was notably more accurate in four-year-olds than in the two-year-olds. More terms had been acquired by the older group than by the younger, the average being eight terms and two terms respectively, and six of the older group had acquired all eleven colour terms.;
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Comprehension was more advanced for both ages than, production, although more terms were produced than were comprehended. No sex differences were found at all. Further analyses concentrated on production performance.;
As expected, the number of colour terms used increased with age and their use became more stable with age. There was no one colour term that appeared in all of the subjects' lexicons, but the colour terms most likely to appear were the primaries and the non-primary ORANGE. BLUE showed a marked, though not significant, preference at both ages and several possible reasons are suggested for this. GREY, as expected, appeared least frequently, followed by the achromatics.;
Colour terms used most accurately were ORANGE and PINK. These appear to be the first colour categories to emerge with separate labels, followed by the primary colours and GREY again ranking lowest. There were no terms which had been acquired by a significantly large number of two-year-olds and none by a significantly small number of four-year-olds. Primary terms as a group were also those most likely to be used incorrectly. Those terms most likely to be overextended;
by the younger subjects were also those without a stable referent, while for the older ones it was those terms which the subject already knew the correct use of. The actual errors did not seem to be based on any of the proposed perceptual properties of colour.;
It is suggested that the child at these stages does not organize his lexical or conceptual colour categories in terms;
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of the adult distinctions of primary/non-primary/achromatic or of hue/saturation/brightness. Further in-depth examination might reveal a base of associative or contextual criteria instead of the random, ad-hoc guesses they appear to be in this study. It is further suggested that such organizational criteria are very individualistic and therefore;
will not fit the generalizations made by previous studies about colour-term acquisition.
Arts, Faculty of
Linguistics, Department of
Graduate
Infection with high-risk human papillomavirus (HPV) type 16 is an independent risk factor for the development of oropharyngeal squamous cell carcinomas (OSCC). However, it is unclear whether viral ...integration is an essential hallmark in the carcinogenic process of OSCC and whether HPV integration correlates with the level of viral gene transcription and influences the expression of disrupted host genes. We analyzed 75 patients with OSCC. HPV16-positivity was proven by p16(INK4A) immunohistochemistry, PCR and FISH. Viral integration was examined using DIPS- as well as APOT-PCR. Viral E2, E6 and E7 gene expression levels were quantified by quantitative reverse transcriptase (RT-q)PCR. Expression levels of 7 human genes disrupted by the virus were extracted from mRNA expression profiling data of 32 OSCCs. Viral copy numbers were assessed by qPCR in 73 tumors. We identified 37 HPV16-human fusion products indicating viral integration in 29 (39%) OSCC. In the remaining tumors (61%) only episome-derived PCR products were detected. When comparing OSCC with or without an integration-derived fusion product, we did not find significant differences in the mean RNA expression of viral genes E2, E6 and E7 or the viral copy numbers per cell, nor did the RNA expression of the HPV-disrupted genes differ from either group of OSCC. In conclusion, our data do not support the hypothesis that integration affects the levels of viral and/or HPV-disrupted human gene transcripts. Thus constitutive, rather than a high level, of expression of oncogene transcripts appears to be required in HPV-related OSCC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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