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41.
42.
YIT ARN TEH OLIVIER MAZÉAS ALYSSA R. ATWOOD TRIFFID ABEL ROBERT C. RHEW 《Global Change Biology》2009,15(2):330-345
The Arctic tundra has been shown to be a potentially significant regional sink for methyl chloride (CH3Cl) and methyl bromide (CH3Br), although prior field studies were spatially and temporally limited, and did not include gross flux measurements. Here we compare net and gross CH3Cl and CH3Br fluxes in the northern coastal plain and continental interior. As expected, both regions were net sinks for CH3Cl and CH3Br. Gross uptake rates (−793 nmol CH3Cl m−2 day−1 and −20.3 nmol CH3Br m−2 day−1) were 20–240% greater than net fluxes, suggesting that the Arctic is an even greater sink than previously believed. Hydrology was the principal regulator of methyl halide flux, with an overall trend towards increasing methyl halide uptake with decreasing soil moisture. Water table depth was one of the best predictors of net and gross uptake, with uptake increasing proportionately with water table depth. In drier areas, gross uptake was very high, averaging −1201 nmol CH3Cl m−2 day−1 and −34.9 nmol CH3Br m−2 day−1; in flooded areas, gross uptake was significantly lower, averaging −61 nmol CH3Cl m−2 day−1 and −2.3 nmol CH3Br m−2 day−1. Net and gross uptake was greater in the continental interior than in the northern coastal plain, presumably due to drier inland conditions. Within certain microtopographic features (low‐ and high‐centered polygons), uptake rates were positively correlated with soil temperature, indicating that temperature played a secondary role in methyl halide uptake. Incubations suggested that the inverse relationship between water content and methyl halide uptake was the result of mass transfer limitation in saturated soils, rather than because of reduced microbial activity under anaerobic conditions. These findings have potential regional significance, as the Arctic is expected to become warmer and drier due to anthropogenic climate forcing, potentially enhancing the Arctic sink for CH3Cl and CH3Br. 相似文献
43.
Research laboratories studying the genetics of companion animals have no database tools specifically designed to aid in the
management of the many kinds of data that are generated, stored and analyzed. We have developed a relational database, "DOG-SPOT,"
to provide such a tool. Implemented in MS-Access, the database is easy to extend or customize to suit a lab's particular needs.
With DOG-SPOT a lab can manage data relating to dogs, breeds, samples, biomaterials, phenotypes, owners, communications, amplicons,
sequences, markers, genotypes and personnel. Such an integrated data structure helps ensure high quality data entry and makes
it easy to track physical stocks of biomaterials and oligonucleotides. 相似文献
44.
LC/MS/NMR analysis of isomeric divanilloylquinic acids from the root bark of Fagara zanthoxyloides Lam 总被引:1,自引:0,他引:1
Ouattara B Angenot L Guissou P Fondu P Dubois J Frédérich M Jansen O van Heugen JC Wauters JN Tits M 《Phytochemistry》2004,65(8):1145-1151
Gradient HPLC coupled to DAD/UV, MS/MS and NMR has been applied to the rapid structure determination of three new isomeric divanilloylquinic acids from Fagara zanthoxyloides collected in Burkina Faso: 3,4-O-divanilloylquinic acid, 3,5-O-divanilloylquinic acid and 4,5-O-divanilloylquinic acid. Furthermore these new compounds named burkinabins A-C could play a useful role in sickle cell disease, as the active agents of Fagara zanthoxylo?des are said to be unidentified aromatic compounds with carboxylic acid grouping (Adesanya, S.A., Sofowora, A., 1983. Biological standardisation of Zanthoxylum roots for antisickling activity. Planta Med. 48, 27-33). 相似文献
45.
JAUME FLEXAS JOSEFINA BOTA JOSEP CIFRE JOSÉ MARIANO ESCALONA JERONI GALMÉS JAVIER GULÍAS EL-KADRI LEFI SARA FLORINDA MARTÍNEZ-CAÑELLAS MARÍA TERESA MORENO MIQUEL RIBAS-CARBÓ DIEGO RIERA BARTOLOMÉ SAMPOL HIPÓLITO MEDRANO 《The Annals of applied biology》2004,144(3):273-283
Photosynthetic down-regulation and/or inhibition under water stress conditions are determinants for plant growth, survival and yield in drought-prone areas. Current knowledge about the sequence of metabolic events that leads to complete inhibition of photosynthesis under severe water stress is reviewed. An analysis of published data reveals that a key regulatory role for Rubisco in photosynthesis is improbable under water stress conditions. By contrast, the little data available for other Calvin cycle enzymes suggest the possibility of a key regulatory role for some enzymes involved in the regeneration of RuBP. There are insufficient data to determine the role of photophosphorylation. Several important gaps in our knowledge of this field are highlighted. The most important is the remarkable scarcity of data about the regulation/inhibition of photosynthetic enzymes other than Rubisco under water stress. Consequently, new experiments are urgently needed to improve our current understanding of photosynthetic down-regulation under water stress. A second gap is the lack of knowledge of photosynthetic recovery after irrigation of plants which have been subjected to different stages of water stress. This knowledge is necessary in order to match physiological down-regulation by water stress with controlled irrigation programmes. 相似文献
46.
47.
Hydroxyurea was used to study the proliferation rate of haemopoietic stem cells (CFUJ in normal mice, after irradiation or transplantation into irradiated recipients. It was demonstrated that the proliferation rate of endogenous CFUS (endo-CFU,) and exogenous CFUS (exo-CFUs) are identical. After irradiation (650 R) the surviving endo-CFUs begin to proliferate immediately. By contrast exo-CFU, transplanted into the irradiated recipient mouse (850 R), begin to proliferate only after about 30 hr. However, injection of isoproterenol (which stimulates adenyl cyclase) or dibutyryl cyclic adenosine 3′,5′-monophosphate shortly after marrow cell graft, triggers the transplanted CFUS into cell cycle as shown by an almost immediately increased sensitivity to hydroxyurea. Isoproterenol is capable of inducing DNA synthesis also in stem cells of normal mice but it takes about 20 hr before CFU, become to be increasingly sensitive to hydroxyurea. 相似文献
48.
Moura G Pinheiro M Silva R Miranda I Afreixo V Dias G Freitas A Oliveira JL Santos MA 《Genome biology》2005,6(3):R28
Codon context is an important feature of gene primary structure that modulates mRNA decoding accuracy. We have developed an analytical software package and a graphical interface for comparative codon context analysis of all the open reading frames in a genome (the ORFeome). Using the complete ORFeome sequences of Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida albicans and Escherichia coli, we show that this methodology permits large-scale codon context comparisons and provides new insight on the rules that govern the evolution of codon-pair context. 相似文献
49.
Honoré G. Ouattara Ban L. Koffi Germain T. Karou Abdourahamane Sangaré Sebastien L. Niamke Jacques K. Diopoh 《World journal of microbiology & biotechnology》2008,24(9):1753-1760
The role of bacilli in cocoa fermentation is not well known. Their potential of production of pectinolytic enzymes during
this process was evaluated. Bacillus growth was monitored and pectinolytic strains were screened for their use of pectin as sole carbon source. Effects of cocoa
fermentation parameters susceptible to influence on enzyme production were analysed. Among 98 strains isolated, 90 were positive
for pectin degradation and 80% of them presented detectable pectinolytic activities in submerged fermentation. Forty-eight
strains produced polygalacturonase (PG), 47 yielded pectin lyase (PL) and 23 strains produced both enzymes. Bacilli growth
was not significantly affected during fermentation. PL production was favoured by galactose, lactose, glucose as sugars, and
arginine, glutamine, cysteine and ammonium sulphate as nitrogen compounds. Pectin at low concentration (0.05%) and iron stimulated
PL production. It was strongly repressed by galacturonic acid (1%), and negatively affected by nitrogen starvation, zinc and
temperatures above 45°C. PL yield was very weak below pH 4.0 and in anaerobic conditions. PG production was weakened by sucrose
and cation depletion. It was increased slightly by cysteine, ammonium nitrate and nitrogen starvation and significantly above
40°C. PG synthesis was not affected by acidic pH (3.0–6.0) or oxygen availability. As fermentation products, lactate and acetate
lowered the production of both enzymes while ethanol had no effect. The high proportion of pectinolytic producers among the
strains studied and analysis of factors influencing pectinolytic enzymes production, suggest that Bacillus sp. is liable to produce at least one enzyme during cocoa fermentation. 相似文献
50.
A. Santovito C. Burgarello P. Cervella G. A. Caravatti M. Ouattara B. Salvarani M. Delpero 《Russian Journal of Genetics》2009,45(7):857-860
The COL1A2 gene is one of the two genes encoding for the polypeptides of type I collagen, that represent the major constituent of skin,
bone, tendons, ligaments, blood vessels, dentin, and many interstitial tissues. The COL1A2 gene deletion polymorphism has been considered as an informative anthropological marker for describing geographically distinct
human populations. Aim of the present study was to investigate the genetic variability at COL1A2 locus in two populations, one belonging to Ouangolodougou (n = 133), a village placed in Northern Ivory Coast, and one belonging to Lecco (n = 70), a village placed in a Northern Italy region called Lombardy. For each sampled population no data are available in
literature. We reported, for the first time, the presence of the deleted allele among Ivorians (0.06), confirming the low
deletion frequency of this polymorphism found in Sub Saharan Africa by other authors. For Italians, frequency analysis of
this gene polymorphism (0.28 for the deleted allele) did not show any significant level of differentiation with respect to
other Italian and European populations.
The article is published in the original. 相似文献