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1.
Sung Ho Son Sung Mee Choi Kum Boo Choi Yun Hee Lee Dea Sook Lee Myung Suk Choi Young Goo Park 《Biotechnology and Bioprocess Engineering》1999,4(2):112-118
Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14
elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented
with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS
vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed
on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more
than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first
round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent
proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell
and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth
and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV
seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the
tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth. 相似文献
2.
In the ecotone research region of the Danube in Austria (Man-and-the-Biosphere (MaB)- project 5/21, Austrian Academy of Science) the macrophytes are one of the most important groups of organisms investigated. The species composition and the plant mass in hydrologically dynamic, and in predominantly stagnant sections of a system of lateral branches and sloughs were studied. This study showed that areas protected from frequent disturbance by floods had a greater number of species and higher biomass of aquatic macrophytes. Some species were shown to be evenly distributed throughout the branch system, whereas other species tended to form rare, but large singular patches. A set of new data elaboration techniques enabled us to describe the distribution pattern of the aquatic vegetation in this large branch system of the River Danube. 相似文献
3.
Culturable Actinobacteria from the Marine Sponge Hymeniacidon perleve: Isolation and Phylogenetic Diversity by 16S rRNA gene-RFLP Analysis 总被引:1,自引:0,他引:1
A total of 106 actinobacteria associated with the marine sponge Hymeniacidon perleve collected from the Yellow Sea, China were isolated using eight different media. The number of species and genera of actinobacteria recovered from the different media varied significantly, underlining the importance of optimizing the isolation conditions. The phylogenetic diversity of the actinobacteria isolates was assessed using 16S rRNA gene amplification–restriction fragment length polymorphism (RFLP) analysis of the 106 strains with different morphologies. The RFLP fingerprinting of selected strains by HhaI-digestion of the 16S rRNA genes resulted in 11 different patterns. The HhaI-RFLP analysis gave good resolution for the identification of the actinobacteria isolates at the genus level. A phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to seven genera of culturable actinobacteria including Actinoalloteichus, Micromonospora, Nocardia, Nocardiopsis, Pseudonocardia, Rhodococcus, and Streptomyces. The dominant genus was Streptomyces, which represented 74% of the isolates. Three of the strains identified are candidates for new species. 相似文献
4.
Abstract Significantly higher Giardia lamblia trophozoites load in the intestine of infected mice accompanied pronounced influx of suppressor/cytotoxic T cells (Lyt 2.2+ ), T cells (Thy 1.2+ ) and significant reduction in IgA-containing cells in the gut during the establishment and peak phases of infection. The induction of helper/inducer T cells (Lyt 1.1+ ) and significant enhancement of IgA-containing cells in gut resulted in the decline of the trophozoite loads. However, the prior treatment of animals with dexamethasone alone resulted in significant reduction in helper/inducer T cells (Lyt 1.1+ ) and the IgA-containing cells in the gut; the percents of suppressor/cytotoxic T cells (Lyt 2.2+ ) and IgM-containing cells remained unaltered. Although the G. lamblia infection in such animals further significantly increased the influx of suppressor/cytotoxic T cells, the late response of helper/inducer T cells and IgA-containing cells was abrogated during the decline phase of infection. The significant reduction in the trophozoite load — despite immuno-suppressive therapy — appeared to be due to unaltered IgM response in such animals which probably took over the function of IgA in defense against G. lamblia . The data of the investigation thus suggested a role of helper/inducer T cells and antibodies producing cells in gut as important effector cells resulting in the termination of primary G. lamblia infection. 相似文献
5.
Xiu L. Chen Nicklaus L. J. E. Wee Kum C. Hiong Jasmine L. Y. Ong You R. Chng Biyun Ching Wai P. Wong Shit F. Chew Yuen K. Ip 《PloS one》2013,8(12)
The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l−1) and accumulate ammonia to high concentrations in its brain (∼4.5 µmol g−1). Na+/K+-ATPase (Nka) is an essential transporter in brain cells, and since NH4
+ can substitute for K+ to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka α-subunits, some of which might have high K+ specificity. Thus, this study aimed to clone and sequence the nka α-subunits from the brain of M. albus, and to determine the effects of ammonia exposure on their mRNA expression and overall protein abundance. The effectiveness of NH4
+ to activate brain Nka from M. albus and Mus musculus was also examined by comparing their Na+/K+-ATPase and Na+/NH4
+-ATPase activities over a range of K+/NH4
+ concentrations. The full length cDNA coding sequences of three nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 expression was undetectable. Exposure to 50 mmol l−1 NH4Cl for 1 day or 6 days resulted in significant decreases in the mRNA expression of nkaα1, nkaα3a and nkaα3b. The overall Nka protein abundance also decreased significantly after 6 days of ammonia exposure. For M. albus, brain Na+/NH4
+-ATPase activities were significantly lower than the Na+/K+-ATPase activities assayed at various NH4
+/K+ concentrations. Furthermore, the effectiveness of NH4
+ to activate Nka from the brain of M. albus was significantly lower than that from the brain of M. musculus, which is ammonia-sensitive. Hence, the (1) lack of nkaα2 expression, (2) high K+ specificity of K+ binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα isoforms and the overall Nka protein abundance in response to ammonia exposure might be some of the contributing factors to the high brain ammonia tolerance in M. albus. 相似文献
6.
Ip Yuen K. Hiong Kum C. Teng Joey H. Q. Boo Mel V. Choo Celine Y. L. Wong Wai P. Chew Shit F. 《Coral reefs (Online)》2020,39(2):451-465
Coral Reefs - Giant clams flourish in nutrient-poor waters of tropical Indo-Pacific because they live in symbiosis with extracellular dinoflagellates (zooxanthellae) and receive photosynthates from... 相似文献
7.
Mayank Singh Clayton R. Hunt Raj K. Pandita Rakesh Kumar Chin-Rang Yang Nobuo Horikoshi Robert Bachoo Sara Serag Michael D. Story Jerry W. Shay Simon N. Powell Arun Gupta Jessie Jeffery Shruti Pandita Benjamin P. C. Chen Dorothee Deckbar Markus L?brich Qin Yang Kum Kum Khanna Howard J. Worman Tej K. Pandita 《Molecular and cellular biology》2013,33(16):3390
8.
Abstact Polar organisms should have mechanisms to survive the extremely cold environment. Four genes encoding cold-shock proteins,
which are small, cold-induced bacterial proteins, have been cloned from the Antarctic bacterium Streptomyces sp. AA8321. Since the specific functions of any polar bacterial or Streptomyces cold-shock proteins have not yet been determined, we examined the role of cold-shock protein A from Streptomyces sp. AA8321 (CspASt). Gel filtration chromatography showed that purified CspASt exists as a homodimer under physiological conditions, and gel shift assays showed that it binds to single-stranded, but not
double-stranded, DNA. Overexpression of CspASt in Escherichia coli severely impaired the ability of the host cells to form colonies, and the cells developed an elongated morphology. Incorporation
of a deoxynucleoside analogue, 5-bromo-2′-deoxyuridine, into newly synthesized DNA was also drastically diminished in CspASt-overexpressing cells. These results suggest that CspASt play a role in inhibition of DNA replication during cold-adaptation. 相似文献
9.
Identification of domains of ataxia-telangiectasia mutated required for nuclear localization and chromatin association 总被引:1,自引:0,他引:1
Young DB Jonnalagadda J Gatei M Jans DA Meyn S Khanna KK 《The Journal of biological chemistry》2005,280(30):27587-27594
Ataxia-telangiectasia mutated (ATM) is essential for rapid induction of cellular responses to DNA double strand breaks (DSBs). In this study, we mapped a nuclear localization signal (NLS), 385KRKK388, within the amino terminus of ATM and demonstrate its recognition by the conventional nuclear import receptor, the importin alpha1/beta1 heterodimer. Although mutation of this NLS resulted in green fluorescent protein (GFP) x ATM(NLSm) localizing predominantly within the cytoplasm, small amounts of nuclear GFP x ATM(NLSm) were still sufficient to elicit a DNA damage response. Insertion of an heterologous nuclear export signal between GFP and ATM(NLSm) resulted in complete cytoplasmic localization of ATM, concomitantly reducing the level of substrate phosphorylation and increasing radiosensitivity, which indicates a functional requirement for ATM nuclear localization. Interestingly, the carboxyl-terminal half of ATM, containing the kinase domain, which localizes to the cytoplasm, could not autophosphorylate itself or phosphorylate substrates, nor could it correct radiosensitivity in response to DSBs even when targeted to the nucleus by insertion of an exogenous NLS, demonstrating that the ATM amino terminus is required for optimal ATM function. Moreover, we have shown that the recruitment/retention of ATM at DSBs requires its kinase activity because a kinase-dead mutant of GFP x ATM failed to form damage-induced foci. Using deletion mutation analysis we mapped a domain in ATM (amino acids 5-224) required for its association with chromatin, which may target ATM to sites of DNA damage. Combined, these data indicate that the amino terminus of ATM is crucial not only for nuclear localization but also for chromatin association, thereby facilitating the kinase activity of ATM in vivo. 相似文献