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991.
Morley SC Weber KS Kao H Allen PM 《Journal of immunology (Baltimore, Md. : 1950)》2008,181(7):4696-4708
Protein kinase C-theta (PKCtheta) is critical for TCR-initiated signaling in mature T cells, but initial reports found no requirement for PKCtheta in thymocyte development. Thymocytes and peripheral T cells utilize many of the same signaling components and, given the significant role of PKCtheta in peripheral T cells, it was surprising that it was not involved at all in TCR signaling in thymocytes. We decided to re-evaluate the role of PKCtheta in thymocyte development using the well-characterized class II-restricted n3.L2 TCR-transgenic TCR model. Analysis of n3.L2 PKCtheta(-/-) mice revealed a defect in thymocyte-positive selection, resulting in a 50% reduction in the generation of n3.L2 CD4 single-positive thymocytes and n3.L2 CD4 mature T cells. Competition between n3.L2 WT and n3.L2 PKCtheta(-/-) thymocytes in bone marrow chimeras revealed a more dramatic defect, with a >80% reduction in generation of n3.L2 CD4 single-positive thymocytes derived from PKCtheta(-/-) mice. Inefficient positive selection of n3.L2 PKCtheta(-/-) CD4 single-positive cells resulted from "weaker" signaling through the TCR and correlated with diminished ERK activation. The defect in positive selection was not complete in the PKCtheta(-/-) mice, most likely accounted for by compensation by other PKC isoforms not evident in peripheral cells. Similar decreased positive selection of both CD4 and CD8 single-positive thymocytes was also seen in nontransgenic PKCtheta(-/-) mice. These findings now place PKCtheta as a key signaling molecule in the positive selection of thymocytes as well as in the activation of mature T cells. 相似文献
992.
993.
We have previously shown that there is high Na(+)/Ca(2+) exchange (NCX) activity in bovine adrenal chromaffin cells. In this study, by monitoring the [Ca(2+)](i) change in single cells and in a population of chromaffin cells, when the reverse mode of exchanger activity has been initiated, we have shown that the NCX activity is enhanced by K(+). The K(+)-enhanced activity accounted for a significant proportion of the Na(+)-dependent Ca(2+) uptake activity in the chromaffin cells. The results support the hypothesis that both NCX and Na(+)/Ca(2+)-K(+) exchanger (NCKX) are co-present in chromaffin cells. The expression of NCKX in chromaffin cells was further confirmed using PCR and northern blotting. In addition to the plasma membrane, the exchanger activity, measured by Na(+)-dependent (45)Ca(2+) uptake, was also present in membrane isolated from the chromaffin granules enriched fraction and the mitochondria enriched fraction. The results support that both NCX and NCKX are present in bovine chromaffin cells and that the regulation of [Ca(2+)](i) is probably more efficient with the participation of NCKX. 相似文献
994.
Suey-Sheng Kao Feng-Chia Hsieh Ching-Chou Tzeng Yeong-Sheng Tsai 《Current microbiology》2003,47(4):0295-0299
A new cry gene (cry1Ca9) was cloned and sequenced from a Bacillus thuringiensis isolate native to Taiwan (G10-01A). The cry1C-type gene, designated cry1Ca9, consisted of an open reading frame of 3,567 bp, encoding a protein of 1,189 amino acid residues. The polypeptide has the deduced amino acid sequences predicting molecular masses of 134.7 kDa. The gene sequence was compared against the GenBank nucleotide sequence data base. It was found that the cry1Ca9 gene coded for a 134.7-kDa protoxin which had greater than 99.8% homology with the previously reported cry1Ca1 gene, as only three mismatches were found between the two amino acid sequences. When the Cry1Ca9 toxin was expressed in a crystal-negative strain of B. thuringiensis (cryB-), elliptical crystals were produced. Cell extracts from this recombinant strain appear to have high insecticidal activity against lepidopteran larvae (Plutella xylostella).Received: 23 September 2002 / Accepted: 6 December 2002 相似文献
995.
T. Tsukamoto T. Ando H. Watanabe H. Kokubun G. Hashimoto U. Sakazaki E. Suárez E. Marchesi K. Oyama T. Kao 《Journal of plant research》2002,115(3):0185-0193
The overall status of self-incompatibility, as assessed by the rate of capsule-set after self-pollination, was investigated
in the genus Calibrachoa (Solanaceae). Thirty-two species were surveyed using a total of 655 individuals collected in 102 different native populations
in Argentina, Brazil, Mexico, and Uruguay. The rate of capsule-set in 278 voucher specimens collected from the same native
habitats was also measured to obtain additional information to assess the degree of self-(in)compatibility. Only one species,
Calibrachoa parviflora, was self-compatible (SC, autogamous) and the other 31 species were found to be self-incompatible (SI). A mixed population
(SI and SC individuals in the same population) was not found. The differentiation of C. parviflora as an autogamous species is associated with a successful occupation of different (riparian) habitats within a larger range
of geographic distribution compared to the rest of the species in the principally SI genus of Calibrachoa.
Received: March 21, 2001 / Accepted: December 25, 2001 相似文献
996.
The possibility that NH4
+ accumulation is linkedto the senescence of detached rice (Oryza sativa) leavesinduced by NaCl was investigated. NaCl was effective in promoting senescenceandin increasing NH4
+ content of detached rice leaves.NaCl-promoted senescence is mainly due to the effect of both Na+ andCl- ions. NaCl had no or slight effect on relative water content,suggesting that an osmotic effect is unlikely to be a major factor contributingto senescence of these leaves. NaCl-induced NH4
+accumulation was due to enhanced nitrate reduction and decreased glutaminesynthetase activity. Exogenous NH4Cl, which caused an accumulationofNH4
+ in detached rice leaves, also promoted senescence.Itwas found that an increase in NH4
+ content preceded theoccurrence of senescence caused by NaCl. Results also show that NaCl-promotedsenescence is unlikely to be due to the lack of glutamate, glutamine,aspartate,and asparagine. The current results suggest that NH4
+accumulation is linked to NaCl-induced rice leaf senescence. Since ethylene isknown to be a potent promoter of leaf senescence, we also investigated the roleof ethylene in the regulation of NH4
+-promoted senescenceof detached rice leaves. NaCl or NH4Cl treatment resulted in adecrease of ethylene production. Evidence was presented to show thatNH4
+ accumulation in detached rice leaves does not changetissue sensitivity to ethylene. Clearly, the possible involvement of ethyleneinNH4
+-promoted senescence is excluded. 相似文献
997.
Axel Pruss Moujahed Kao Uwe Gohs Jürgen Koscielny Rüdiger von Versen Georg Pauli 《Biologicals》2002,30(2):125-133
In the production of bone grafts intended for transplantation, basic safety measures to avoid the transmission of pathogens are selection and serological screening of donors for markers of virus infections. As an additional safety tool we investigated the effect of gamma irradiation on the sterility of human bone diaphysis transplants and evaluated its impact on the virus safety of transplants. Model viruses were included in the study to determine the dose necessary to achieve a reduction factor for the infectivity titres of at least 4 log(10) at a temperature of -30+/-5 degrees C. The following viruses were used: human immunodeficiency virus type 2 (HIV-2), hepatitis A virus (HAV), and poliovirus (PV-1), and the following model viruses: pseudorabies virus (PRV) as a model for human herpesviruses, bovine viral diarrhoea virus (BVDV) for HCV, and bovine parvovirus (BPV) for parvovirus B19. A first approach was to determine the D(10) values (kGy) for the different viruses (virus inactivation kinetics: BPV 7.3; PV-1 7.1; HIV-2 7.1; HAV 5.3; PRV 5.3; BVDV <3.0 kGy). Based on these results, inactivation of these viruses was studied in experimentally contaminated human bone transplants (femoral diaphyses). For BPV, the most resistant one of the viruses studied, a dose of approximately 34 kGy was necessary to achieve a reduction of infectivity titres of 4 log(10). We therefore recommend a dose of 34 kGy for the sterilisation of frozen bone transplants. 相似文献
998.
Peng Ying Zhang Jin Chang Wang Sheng Hao Liu Kao Shan Chen 《Journal of Phytopathology》2009,157(4):201-207
The ability of burdock fructooligosaccharide (BFO), a type of linear fructooligosaccharide extracted and isolated from the roots of Arctium lappa , to induce systemic acquired resistance (SAR) was studied in cucumber seedlings. BFO strongly induced changes in salicylic acid (SA) and SA-glucoside (SAG) in BFO-treated leaves, and similar changes of SA and SAG were also found in untreated leaves of the same seedling. The level of SA in the first leaves sprayed with BFO (5.0 g/l) increased by 3.6 times after 24 h and then gradually declined from 48 to 96 h and finally decreased to a nadir at 120 h. The SAG level increased by 2.1 times at 24 h and then continued to increase to about 10.0 times as much as that in control from 96 to 120 h. The levels of SA in the untreated leaves of the same seedling only increased by 1.6–1.9 times during the period of 24–72 h followed by a decrease at 120 h, while SAG increased by 1.1 times at 24 h but steadily continued to increase to its maximum from 24 to 120 h. In summary, the patterns of expression of SA and SAG in the untreated leaf were similar to that of the treated leaf of the same seedling, while the pattern of expression of SAG was quite different from that of SA both in the treated and untreated leaves. Pretreatment with BFO reduced the lesions caused by Colletotrichum orbiculare by 56.8%. Additionally, the amount of lignin and the activities of some defensive enzymes including peroxidase, superoxide dismutase, polyphenoloxidase and β-1,3-glucanase significantly increased in the first leaves pretreated with BFO and followed with C. orbiculare inoculation. These results demonstrate that BFO can enhance the contents of endogenous SA, the resistance against C. orbiculare , and the activities of defensive enzymes of cucumber seedlings. 相似文献
999.
Lipid accumulation and CO2 utilization of Nannochloropsis oculata in response to CO2 aeration 总被引:2,自引:0,他引:2
In order to produce microalgal lipids that can be transformed to biodiesel fuel, effects of concentration of CO(2) aeration on the biomass production and lipid accumulation of Nannochloropsis oculata in a semicontinuous culture were investigated in this study. Lipid content of N. oculata cells at different growth phases was also explored. The results showed that the lipid accumulation from logarithmic phase to stationary phase of N. oculata NCTU-3 was significantly increased from 30.8% to 50.4%. In the microalgal cultures aerated with 2%, 5%, 10% and 15% CO(2), the maximal biomass and lipid productivity in the semicontinuous system were 0.480 and 0.142 g L(-1)d(-1) with 2% CO(2) aeration, respectively. Even the N. oculata NCTU-3 cultured in the semicontinuous system aerated with 15% CO(2), the biomass and lipid productivity could reach to 0.372 and 0.084 g L(-1)d(-1), respectively. In the comparison of productive efficiencies, the semicontinuous system was operated with two culture approaches over 12d. The biomass and lipid productivity of N. oculata NCTU-3 were 0.497 and 0.151 g L(-1)d(-1) in one-day replacement (half broth was replaced each day), and were 0.296 and 0.121 g L(-1)d(-1) in three-day replacement (three fifth broth was replaced every 3d), respectively. To optimize the condition for long-term biomass and lipid yield from N. oculata NCTU-3, this microalga was suggested to grow in the semicontinuous system aerated with 2% CO(2) and operated by one-day replacement. 相似文献
1000.