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31.
Yams (Dioscorea spp.) consist of approximately 600 species. Presently, these species are threatened by genetic erosion due to many factors such as pest attacks and farming practices. In parallel, complex taxonomic boundaries in this genus makes it more challenging to properly address the genetic diversity of yam and manage its germplasm. As a first step toward evaluating and preserving the genetic diversity yam species, we use a phylogenetic diversity (PD) approach that has the advantage to investigate phylogenetic relationships and test hypotheses of species monophyly while alleviating to the problem of ploidy variation within and among species. The Bayesian phylogenetic analysis of 62 accessions from 7 species from three regions of Cameroon showed that most Dioscorea sections were monophyletic, but species within sections were generally non-monophyletic. The wild species D. praehensilis and cultivated D. cayenensis were the species with the highest PD. At the opposite, D. esculenta has a low PD and future studies should focus on this species to properly address its conservation status. We also show that wild species show a stronger genetic structure than cultivated species, which potentially reflects the management of the yam germplasm by farmers. These findings show that phylogenetic diversity is a promising approach for an initial investigation of genetic diversity in a crop consisting of closely related species. 相似文献
32.
Ngo Thi Hai Yen Xenia Bogdanović Gottfried J. Palm Olaf Kühl Winfried Hinrichs 《Journal of biological inorganic chemistry》2010,15(2):195-201
Crystal structures of polypeptide deformylase (PDF) of Escherichia coli with nickel(II) replacing the native iron(II) have been solved with chloride and formate as metal ligands. The chloro complex
is a model for the correct protonation state of the hydrolytic hydroxo ligand and the protonated status of the Glu133 side
chain as part of the hydrolytic mechanism. The ambiguity that recently some PDFs have been identified with Zn2+ ion as the active-site centre whereas others are only active with Fe2+ (or Co2+, Ni2+) is discussed with respect to Lewis acid criteria of the metal ion and substrate activation by the CD loop. 相似文献
33.
Ferdinand Bohlmann Karl-Heinz Knoll Christa Zdero Pradip Kumar Mahanta Michael Grenz Albert Suwita Dorothea Ehlers Ngo Le Van Wolf-Rainer Abraham Arvind Anant Natu 《Phytochemistry》1977,16(7):965-985
Investigation of about 50 Senecio species has afforded many new substances, in addition to known compounds. Present in these plants are 23 fura 相似文献
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Coelomocytes, the immunodefense cells of the earthworm Lumbricus terrestris, are exposed to changing osmotic pressures as the worm's coelomic fluid responds to fluctuating wet-dry conditions of the surrounding soil. Using light and fluorescence microscopy combined with actin and tubulin disrupting drugs, we determined the effects of changing osmotic pressure on coelomocyte morphology. The coelomocytes from L. terrestris respond to an increase in environmental osmotic pressure from isotonic conditions (170 mOsm) to hypertonic conditions (715 mOsm) by changing from a round/petalloid morphology to a filopodial morphology. Cytoskeletal fluorescent staining studies indicate that for filopodia to form, the actin cortical ring, present in most coelomocytes in isotonic conditions, must be disrupted. Breakdown of the actin ring by exposure to a hypertonic environment or actin disrupting drugs allows the formation of actin or tubulin-based filopodia. The filopodia, or podial-like extensions formed by earthworm coelomocytes, may enable the cells to better explore their environment. 相似文献
37.
Chiemchaisri W Chiemchaisri C Dumrongsukit C Threedeach S Ngo HH Vigneswaran S 《Bioresource technology》2011,102(9):5438-5443
Floating plastic media pre-filter (PP) in combination with microfiltration membrane (MF) was applied to the removal of water-borne microorganism from surface water. The system was operated with and without coagulant addition. Jar-test results suggested that alum and polyaluminum chloride could effectively remove turbidity, fecal coliforms (FC) and algae at their optimum doses. Nevertheless, none of those coagulants could accomplish high coliphage (CP) removal. Microorganism removal in the system was increasing along with time in the PP unit operated at 5-m3/m2/h filtration rate but opposite trend was observed at higher filtration rates (10-15 m3/m2/h). Different coagulant types and filtration rates employed in the PP unit also affected microorganism removal in MF unit. The operation of PP unit at a filtration rate of 15 m3/m2/h and MF unit at a filtration rate of 0.6 m3/m2/d could achieve satisfactory turbidity and overall microorganism removal. 相似文献
38.
In this study, fast pyrolysis of palm kernel cake (PKC) was carried out in a closed-tubular reactor over a temperature range of 550 to 750 °C with various retention times. The pyrolyzing gas products mainly included CO, CO2, and light hydrocarbons; it is noted that no hydrogen was detected in the product. In order to investigate the reaction pathway, the kinetic lump model of Liden was applied to verify and calculate all rate constants. The results obtained at different temperatures indicated that the rate constant increased with pyrolysis temperature. Furthermore, the experimental results were in good agreement with the proposed mechanism. 相似文献
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So MT Leon TY Cheng G Tang CS Miao XP Cornes BK Diem NN Cui L Ngan ES Lui VC Wu XZ Wang B Wang H Yuan ZW Huang LM Li L Xia H Zhu D Liu J Nguyen TL Chan IH Chung PH Liu XL Zhang R Wong KK Sham PC Cherny SS Tam PK Garcia-Barcelo MM 《PloS one》2011,6(12):e28986
Rare (RVs) and common variants of the RET gene contribute to Hirschsprung disease (HSCR; congenital aganglionosis). While RET common variants are strongly associated with the commonest manifestation of the disease (males; short-segment aganglionosis; sporadic), rare coding sequence (CDS) variants are more frequently found in the lesser common and more severe forms of the disease (females; long/total colonic aganglionosis; familial).Here we present the screening for RVs in the RET CDS and intron/exon boundaries of 601 Chinese HSCR patients, the largest number of patients ever reported. We identified 61 different heterozygous RVs (50 novel) distributed among 100 patients (16.64%). Those include 14 silent, 29 missense, 5 nonsense, 4 frame-shifts, and one in-frame amino-acid deletion in the CDS, two splice-site deletions, 4 nucleotide substitutions and a 22-bp deletion in the intron/exon boundaries and 1 single-nucleotide substitution in the 5' untranslated region. Exonic variants were mainly clustered in RET the extracellular domain. RET RVs were more frequent among patients with the most severe phenotype (24% vs. 15% in short-HSCR). Phasing RVs with the RET HSCR-associated haplotype suggests that RVs do not underlie the undisputable association of RET common variants with HSCR. None of the variants were found in 250 Chinese controls. 相似文献