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1.
目的甲型H1N1流感病毒A/California/7/2009与A/California/4/2009病毒序列比较同源性在99%以上,本实验旨在比较两株病毒感染BALB/c小鼠研究感染力强弱。方法分别将A/California/7/2009(CA7)与A/California/4/2009(CA4)两株病毒分别连续10倍稀释后,对4~6周龄雌性BALB/c小鼠经乙醚麻醉后进行滴鼻攻毒,每个稀释度接种10只实验小鼠,测定CA7 MLD50为101.24/0.05 mL,检测小鼠感染、致病的多项指标,观察期为14 d。结果相同TCID50的CA7和CA4病毒感染小鼠,CA4感染小鼠后14 d内死亡率为20%,而CA7感染小鼠后8 d内死亡率为100%。CA7 106TCID50感染的小鼠病理表现为重度弥漫性间质性肺炎,CA4 106TCID50感染的小鼠病理表现为中度-重度间质性肺炎。结论在相同条件下,CA7感染力明显强于CA4。 相似文献
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The parameters estimated from traditional A/C
i curve analysis are dependent upon some underlying assumptions that substomatal CO2 concentration (C
i) equals the chloroplast CO2 concentration (C
c) and the C
i value at which the A/C
i curve switches between Rubisco- and electron transport-limited portions of the curve (C
i-t) is set to a constant. However, the assumptions reduced the accuracy of parameter estimation significantly without taking
the influence of C
i-t value and mesophyll conductance (g
m) on parameters into account. Based on the analysis of Larix gmelinii’s A/C
i curves, it showed the C
i-t value varied significantly, ranging from 24 Pa to 72 Pa and averaging 38 Pa. t-test demonstrated there were significant differences in parameters respectively estimated from A/C
i and A/C
c curve analysis (p<0.01). Compared with the maximum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), the maximum electron transport rate (Jmax) and Jmax/Vcmax estimated from A/C
c curve analysis which considers the effects of g
m limit and simultaneously fits parameters with the whole A/C
c curve, mean Vcmax estimated from A/C
i curve analysis (Vcmax-C
i) was underestimated by 37.49%; mean Jmax estimated from A/C
i curve analysis (Jmax-C
i) was overestimated by 17.8% and (Jmax-C
i)/(Vcmax-C
i) was overestimated by 24.2%. However, there was a significant linear relationship between Vcmax estimated from A/C
i curve analysis and Vcmax estimated from A/C
c curve analysis, so was it Jmax (p<0.05). 相似文献
4.
R. P. Erickson C. J. Betlach C. J. Epstein 《Differentiation; research in biological diversity》1974,2(4):203-210
RNA precursor uptake and incorporation, amino acid uptake and incorporation, and the characterization of newly synthesized RNA and protein in pools of normal morulae and pools containing one-third t 12 / t 12 morulae were compared. Maturing spermatoza of +/+ and T / t 12 animals were analyzed for RNA and protein content, and the RNA characterized. No differences in these parameters could be ascribed to the t 12 gene in homozygous embryos or haploid sperm. 相似文献
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Flaviano S. Martins Aparecida A. Silva Angélica T. Vieira Flávio H. F. Barbosa Rosa M. E. Arantes Mauro M. Teixeira Jacques Robert Nicoli 《Archives of microbiology》2009,191(8):623-630
The present work investigates some probiotic properties of four different microorganisms (Bifidobacterium animalis var. lactis BB-12, Escherichia coli EMO, Lactobacillus casei and Saccharomyces boulardii). In vitro and in vivo tests were carried out to compare cell wall hydrophobicity, production of antagonistic substances,
survival capacity in the gastrointestinal tract of germ-free mice without pathological consequence, and immune modulation
by stimulation of Küpffer cells, intestinal sIgA and IL-10 levels. In vitro antagonism against pathogenic bacteria and yeast
was only observed for the probiotic bacteria B. animalis and L. casei. The hydrophobic property of the cell wall was higher for B. animalis and E. coli EMO, and this property could be responsible for a better ability to colonize the gastrointestinal tract of germ-free mice.
Higher levels of sIgA were observed mainly for S. boulardii, followed by E. coli EMO and B. animalis, and only S. boulardii induced a significant higher level of IL-10. In conclusion, for a probiotic use, S. boulardii presented better characteristics in terms of immunomodulation, and B. animalis and L. casei for antagonistic substance production. The knowledge of the different probiotic properties could be used to choice the better
microorganism depending on the therapeutic or prophylactic application. 相似文献
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Four New World genera are included in the tribe tigrideae of the Iridaceae. These genera, which have been the subject of recent systematic treatments [1–4], share many characteristics; e.g. a haploid complement of two large and 12 small chromosomes and bisulcate pollen grains. However, the taxonomic and phyletic relationships within and between these genera have been based strictly on floral morphology and may simply reflect the primary pollinators of these genera [4,5].The flavonoid chemistry of eight species in three of the four genera, Rigidella, Sessilanthera and Fosteria, was investigated as part of a systematic study of Tigrideae. Our results are summarized in Table 1 nad Fig. 1. Although a recurrent pattern of and xanthones characterize the leaves of these taxa, each species exhibits a distinctive array of compounds. The same classes of compounds occur in other tribes of the Iridaceae: occur in the Irideae [6,7], Cipureae, and Mariceae and xanthones in Irideae [6] and Sisyrinchieae [6]. 相似文献
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cis-Phytoene and trans-phytofluene were identified in illuminated cultures of Verticillium agaricinum in addition to the other carotenoids 相似文献
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Photosynthetic CO2 -fixation, chlorophyll content, growth rate and nitrate reductase activity were used to examine the influence of NH+ 4 -N and NO− 3 -N on Sphagnum magellanicum cultivated under defined conditions in phytotrons. NO− 3 -concentrations up to 322 μ M were found to be favourable. Increased NH+ 4 concentrations, however, resulted in growth inhibition and decreased chlorophyll content at concentrations ≧ 255 μ M ; e.g. 600 μ M NH+ 4 caused a 20% reduction of nitrate reductase activity and net photosynthesis. For raised bog Sphagna an improved standard nutrient solution is proposed with the following ion concentrations (μ M ): 55 Na+ ; 17 K+ ; 95 NH+ 4 ; 22 Ca2+ ; 22 Mg2+ ; 2 Fe3+ ; 20 Cl− ; 100 NO− 3 ; 57 SO2- 4 ; 7.4 H2 PO− 4 ; trace elements: A-Z solution (Hoagland) 50 μl 1000 ml−1 ; pH 5.8. 相似文献
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When isolated chromatin is incubated with the carcinogens N-methyl-N-nitrosourea (MeNU) and N-ethyl-N-nitrosourea (EtNU), DNA and chromosomal proteins become alkylated to increasingly greater extents as the carcinogen concentrations increase. With either MeNU or EtNU, the core and linker DNA of chromatin are alkylated to essentially identical extents. Alkylation of chromatin DNA as well as free DNA is drastically reduced at physiological ionic strengths (e.g. 0.15 M NaCl). The presence of 0.15 M NaCl, on the other hand, enhances alkylation of chromosomal proteins. While EtNU is much less reactive to DNA than MeNU, alkylation of chromosomal proteins relative to that of chromatin DNA has been found to be markedly greater with EtNU than with MeNU. Such a difference in their relative reactivities toward DNA and proteins may be related to the known difference of carcinogenic potency between these N-nitroso compounds. 相似文献
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Marvin D. Armstrong 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,587(4):638-642
Nδ-Acetylornithine and S-methylcysteine have been identified as minor components of deproteinized blood plasma of human and bovine blood. Human blood plasma contains a variable amount of acetylornithine, averaging 1.1 ± 0.4 μmol/l (range 0.8–0.2 μmol/l). Urine contains a very small amount of acetylornithine, approximately 1 nmol/mg creatinine (1 μmol/day). Human blood plasma contains 3.9 ± 1.9 μmol/l (range 1.4–6.5 μmol/l) of S-methylcysteine. Urine contains approximately 5 nmol/mg creatinine; after acid hydrolysis the amount is increased to 20 nmol/mg creatinine. 相似文献
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Jesús Sanmartín Ana M. García-Deibe Matilde Fondo Fernando Novio Noelia Ocampo Manuel R. Bermejo 《Inorganica chimica acta》2006,359(10):3156-3166
A symmetric diimine ligand containing a CH2PhCH2 bridging group (H2XyTs: N,N′-bis(2-tosylaminobenzylidene)-1,4-xylylenediamine) and its neutral CoII and ZnII dinuclear complexes have been prepared. Two different crystal structures of the free ligand, H2XyTs, and that corresponding to [Co2(XyTs)2], have been solved by X-ray diffraction methods. These revealed two different conformations (syn-anti and anti-anti) for H2XyTs and an infrequent rotational isomerism on the xylylene rings of its CoII dinuclear complex, where both ligands are syn-anti conformed. Characterisation of the compounds is completed with FT-IR, ESI-MS and 1H NMR spectroscopic techniques, when possible. 相似文献
13.
Werner Selbitschka Walter Arnold Ursula B. Priefer Thomas Rottsch?fer Michael Schmidt Reinhard Simon Alfred Pühler 《Molecular & general genetics : MGG》1991,229(1):86-95
Summary DNA fragments carrying the recA genes of Rhizobium meliloti and Rhizobium leguminosarum biovar viciae were isolated by complementing a UV-sensitive recA
–
Escherichia coli strain. Sequence analysis revealed that the coding region of the R. meliloti recA gene consists of 1044 by coding for 348 amino acids whereas the coding region of the R. leguminosarum bv. viciae recA gene has 1053 bp specifying 351 amino acids. The R. meliloti and R. leguminosarum bv. viciae recA genes show 84.8% homology at the DNA sequence level and of 90.1% at the amino acid sequence level. recA
– mutant strains of both Rhizobium species were constructed by inserting a gentamicin resistance cassette into the respective recA gene. The resulting recA mutants exhibited an increased sensitivity to UV irradiation, were impaired in their ability to perform homologous recombination and showed a slightly reduced growth rate when compared with the respective wild-type strains. The Rhizobium recA strains did not have altered symbiotic nitrogen fixation capacity. Therefore, they represent ideal candidates for release experiments with impaired strains.The accession numbers: X59956 R. LEGUMINOSARUM REC A ALAS-DNA; X59957 R. MELITOTI REC A ALAS-DNA 相似文献
14.
R. J. Swap J. N. Aranibar P. R. Dowty W. P. Gilhooly III S. A. Macko 《Global Change Biology》2004,10(3):350-358
The mean annual rainfall in southern Africa is found to explain over half of the observed variance in the stable nitrogen (N) isotopic signatures of C3 vegetation in southern Africa (r2=0.54, P<0.01). The inverse relationship between the stable N isotopic signatures of foliar samples from C3 vegetation and long‐term southern African rainfall is found on a scale larger than previously observed. A modest relationship is found between stable carbon (C) isotopic signatures of C3 vegetation and rainfall across the region (r2=0.20, P<0.01). No such relationship is found between stable C and N isotopic signatures of C4 vegetation and rainfall. The explanation of the relationship between 15N in C3 vegetation and the mean annual rainfall presented here is that nutrient availability varies inversely with water availability. This suggests that water‐limited systems in southern Africa are more open in terms of nutrient cycling and therefore the resulting natural abundance of foliar 15N in these systems is enriched. The use of this relationship may be of value to those researchers modeling both the dynamics of vegetation and biogeochemistry across this region. The use of the isotopic enrichment in C3 vegetation as a function of rainfall may provide an insight into nutrient cycling across the semi‐arid and arid regions of southern Africa. This finding has implications for the study of global change, especially as it relates to vegetation responses to changing regional rainfall regimes over time. 相似文献
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Penicillium brevicompactum; fungus; biosynthesis; N-benzoylphenylalanine; N-benzoylphenylalaninol 相似文献
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William E. Alborn Jr. Joann Hoskins Serhat Ünal Jane E. Flokowitsch Carolyn A. Hayes Joe E.Dotzlaf W. K. Yeh Paul L. Skatrud 《Gene》1996,180(1-2):177-181
A DNA fragment was identified and cloned from Staphylococcus epidermidis (Se) using femA from S. aureus (Sa) as a heterologous hybridization probe. DNA sequence analysis of a portion of this clone revealed two complete ORFs highly related to femA and femB of Sa. The genomic arrangement of the Se femA/B complex was nearly identical to that observed in Sa. Intra- and interspecies relatedness of these genes and conservation of genomic organization were consistent with gene duplication of one of these genes in an ancestral organism. Recombinant FEMA, produced in Escherichia coli (Ec), was purified to near homogeneity. Identity of the purified protein was verified by N-terminal amino acid (aa) sequence analysis. 相似文献
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以切花百合(Lilium brownii var. viridulum)‘卡瓦纳’cDNA为模板,克隆了过氧化氢酶(LbCAT)和谷胱甘肽过氧化物酶(LbGPX)基因。序列分析表明,这2个基因分别包含1 479 bp和519 bp的开放阅读框(ORF),编码492个和172个氨基酸。进化分析结果表明,LbCAT蛋白与岷江百合CAT蛋白的氨基酸序列相似性最高(99.19%),且亲缘关系最近;LbGPX蛋白与油棕GPX蛋白的氨基酸序列相似性最高(78.61%),亲缘关系最近。qRT PCR结果显示,LbCAT和LbGPX在百合根、鳞茎、叶和花中都有表达。LbCAT在叶中表达量最高,LbGPX在花中表达量最高。这2个基因在百合花蕾的生长发育过程中均有表达,且表达量逐渐增加;在PEG处理后2个基因的转录水平升高,但独角金内酯(SLs)处理却显著降低了这2个基因的转录水平;该结果为百合抗逆性机理研究以及抗逆育种奠定了基础。 相似文献
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A hepatotoxic dose of bromobenzene (3 mmoles/kg) decreases hepatic glutathione concentration in rats by approximately 80% within 5 hr following ip injection. A major bromobenzene metabolite, p-bromophenol at a similar dose did not significantly alter hepatic glutathione levels compared to controls. Twenty four hr after administration, serum glutamate pyruvate transaminase (SGPT) levels were significantly increased by bromobenzene but not by p-bromophenol. After 14C-bromobenzene administration, a significant amount of covalently bound radiolabel was detected in liver, kidney and small intestine. A small amount of covalently bound radiolabel was also detected in the lung. After a similar dose of 14C-bromophenol, covalently bound radiolabel was found in liver (62% of the amount detected with 14C-bromobenzene) and smaller amounts were detected in kidney, small intestine and lung. These data are consistent with the view that the hepatotoxity and glutathione depleting ability of bromobenzene are mediated mainly by bromobenzene-3, 4-oxide rather than by chemically reactive metabolites of p-bromophenol derived from bromobenzene. Covalently bound radiolabel from 14C-bromobenzene, however, may be derived from both bromobenzene-3, 4-oxide and the nontoxic reactive metabolites of p-bromophenol. 相似文献