Plasma acceleration above martian magnetic anomalies     

Lundin R  Winningham D  Barabash S  Frahm R  Holmström M  Sauvaud JA  Fedorov A  Asamura K  Coates AJ  Soobiah Y  Hsieh KC  Grande M  Koskinen H  Kallio E  Kozyra J  Woch J  Fraenz M  Brain D  Luhmann J  McKenna-Lawler S  Orsini RS  Brandt P  Wurz P 《Science (New York, N.Y.)》2006,311(5763):980-983

Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.  相似文献   

Methylation of tRNAAsp by the DNA methyltransferase homolog Dnmt2   总被引：1，自引：0，他引：1  

Goll MG  Kirpekar F  Maggert KA  Yoder JA  Hsieh CL  Zhang X  Golic KG  Jacobsen SE  Bestor TH 《Science (New York, N.Y.)》2006,311(5759):395-398

The sequence and the structure of DNA methyltransferase-2 (Dnmt2) bear close affinities to authentic DNA cytosine methyltransferases. A combined genetic and biochemical approach revealed that human DNMT2 did not methylate DNA but instead methylated a small RNA; mass spectrometry showed that this RNA is aspartic acid transfer RNA (tRNA(Asp)) and that DNMT2 specifically methylated cytosine 38 in the anticodon loop. The function of DNMT2 is highly conserved, and human DNMT2 protein restored methylation in vitro to tRNA(Asp) from Dnmt2-deficient strains of mouse, Arabidopsis thaliana, and Drosophila melanogaster in a manner that was dependent on preexisting patterns of modified nucleosides. Indirect sequence recognition is also a feature of eukaryotic DNA methyltransferases, which may have arisen from a Dnmt2-like RNA methyltransferase.  相似文献   

Molecular cloning and functional identification of invertase isozymes from green bamboo Bambusa oldhamii     

Hsieh CW  Liu LK  Yeh SH  Chen CF  Lin HI  Sung HY  Wang AY 《Journal of agricultural and food chemistry》2006,54(8):3101-3107

Three Bo beta fruct cDNAs encoding acid invertases were cloned from shoots of the green bamboo Bambusa oldhamii. On the basis of the amino acid sequences of their products and phylogenetic analyses, Bo beta fruct1 and Bo beta fruct2 were determined to encode cell wall invertases, whereas Bo beta fruct3encodes a vacuolar invertase. The recombinant proteins encoded by Bo beta fruct2 and Bo beta fruct3 were produced in Pichia pastoris and purified to near homogeneity using ammonium sulfate fractionation and immobilized metal affinity chromatography. The pH optima, pI values, and substrate specificities of the isolated enzymes were consistent with those of plant cell wall or vacuolar invertases. The growth-dependent expression of Bo beta fruct1 and Bo beta fruct2 in the base regions of shoots underscores their roles in sucrose unloading and providing substrates for shoot growth. Its high sucrose affinity suggests that the Bo beta fruct2-encoded enzyme is important for maintaining the sucrose gradient between source and sink organs, while the predominant expression of Bo beta fruct3 in regions of active cell differentiation and expansion suggests functions in osmoregulation and cell enlargement.  相似文献   

Production of ascorbyl palmitate by surfactant-coated lipase in organic media     

Hsieh HJ  Nair GR  Wu WT 《Journal of agricultural and food chemistry》2006,54(16):5777-5781

The surface of a lipase from Burkholderia cepacia was coated with a nonionic surfactant, propylene glycol monostearate, and was used as a biocatalyst in the production of ascorbic acid in tert-butyl alcohol. The influence of various factors such as the type of surfactant, the pH of the buffer used for coating, the amount of surfactant in the coating, the organic solvent, and the temperature and molar ratio of the substrates used in the reaction on the conversion of ascorbyl palmitate were studied. After 24 h of reaction at 50 degrees C, a conversion of 47% was obtained using an ascorbic acid to palmitic acid molar ratio of 1:6. The native lipase showed only 6% conversion.  相似文献   

In situ hybridization and RT-PCR detection of Macrobrachium rosenbergii nodavirus in giant freshwater prawn, Macrobrachium rosenbergii (de Man), in Taiwan     

Hsieh CY  Wu ZB  Tung MC  Tu C  Lo SP  Chang TC  Chang CD  Chen SC  Hsieh YC  Tsai SS 《Journal of fish diseases》2006,29(11):665-671

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Heat-killed cells of lactobacilli skew the immune response toward T helper 1 polarization in mouse splenocytes and dendritic cell-treated T cells     

Chuang L  Wu KG  Pai C  Hsieh PS  Tsai JJ  Yen JH  Lin MY 《Journal of agricultural and food chemistry》2007,55(26):11080-11086

It is believed that probiotics play an important role for the health of the host, including modulation of immune responses. Most studies have focused on the immunomodulatory effects of viable cells of lactic acid bacteria; however, we investigated those of heat-killed cells of lactic acid bacteria in this study. We first observed the effects on immune functions via stimulating splenocytes with three heat-killed Lactobacillus strains. Furthermore, we also investigated the effect of mouse dendritic cells (DCs) treated with these heat-killed Lactobacillus strains on T cell responses. The results showed that these Lactobacillus strains were able to stimulate cell proliferation and interleukin (IL)-10, IL-12 p70, and interferon (IFN)-gamma production but not transforming growth factor (TGF)-beta in splenocytes. In addition, these heat-killed Lactobacillus strains also stimulated high-level secretion of IL-12 p70 in DCs and switched T cells to T helper (Th) 1 immune responses, as evidenced by the elevated secretion of IFN-gamma but not IL-5, IL-13, and TGF-beta. These results showed that lactobacilli play a potentially important role in modulating immune responses and allergic reactions.  相似文献   

Effects of diets containing different carbohydrates on starved condition in juvenile tilapia Oreochromis niloticus×O. aureus     

Shu-Ling Hsieh  Shi-Yen Shiau 《Fisheries Science》2000,66(1):32-37

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Inheritance of black leaf mold resistance in tomato   总被引：1，自引：0，他引：1  

T. C. Wang  L. L. Black  W. H. Hsieh  P. M. Hanson 《Euphytica》1995,86(2):111-115

Summary Inheritance of black leaf mold (BLM) (caused by Pseudocercospora fuligena) resistance was studied in four crosses involving two resistant Lycopersicon accessions (PI134417, L. hirsutum and PI254655, L. esculentum) and four susceptible Asian Vegetable Research and Development Center tomato lines (CLN657BC₁F₂-267-0-3-12-7, CL143-0-10-3-0-1-10, CLN698BC₁F₂-358-4-13 and CL5915-93D₄-1-0-3). For each cross, six generations, i.e. P₁, P₂, F₁, F₂, BC₁F₁ and BC₁F₂ were evaluated following inoculations with isolate Pf-2 of P. fuligena. Chi-square analyses of the data based on the ratio of resistant to susceptible plants in the F₂ in three of four crosses gave a good fit to a segregation ratio of 1 R : 15 S, and BC₁F₂ data in three of four crosses gave an acceptable fit to the segregation ratio of 1 R : 63 S. The results indicate that resistance to BLM may be conditioned by two recessive genes acting epistatically in both PI134417 and PI254655.  相似文献   

Genetic analysis and molecular mapping of QTLs associated with resistance to bacterial blight in a rice mutant,SA0423     

Hsin-Yi Tseng  Da-Gin Lin  Hsiao-Ying Hsieh  Ya-June Tseng  Wen-Bin Tseng  Chun-Wei Chen  Chang-Sheng Wang 《Euphytica》2015,205(1):231-241

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Radiation induced variations in photoperiod-sensitivity,thermo-sensitivity and the number of days to heading in rice     

S. C. Hsieh  T. M. Chang 《Euphytica》1975,24(2):487-496

Summary Radiation induced semi-dwarf mutants derived from five japonica type varieties of rice were studied with regard to their photoperiod-sensitivity, thermo-sensitivity and the number of days to heading. The experiment was carried out under the natural conditions at Taipei. The coefficient of photoperiod-sensitivity (T.D.M.) and thermo-sensitivity (byx. z and byz. x) as developed by Oka (1954) were estimated for the mutants in comparison with their original varieties.It was observed that these various physiological characters could be altered rather easily by mutations. Mutants showed wider ranges in both positive and negative directions than their original varieties in all the physiological characters studied. Even though heading date depends on both photoperiod-sensitivity and thermo-sensitivity, it was estimated which of the two contributed more to the induced earliness in each mutant. This offers a basis for selecting early maturing lines of rice.Taiwan Agricultural Research Institute, Taipei, Taiwan, Republic of China.  相似文献