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21.
We studied the relationship between plant stress intensity and herbivore response in the grass miner Chromatomyia milii (Kaltenbach) (Diptera: Agromyzidae) on nutrient stressed plants. We subjected the host grass Holcus lanatus (Poaceae) to a range of nutrient treatments (0%, 25%, 50%, 100%, and 200% Hoagland nutrient solution) and recorded plant stress intensity (plant growth and foliar chlorophyll a and b levels) and offspring performance of C. milii. Plant growth and foliar chlorophyll a and b levels decreased from the 25% treatment to the 200% treatment. The plant stress intensity from the 0% treatment was equal to or only slightly higher than the 25% treatment. Offspring survival of C. milii was lower on the 100% and the 200% treatments than on the other treatments. Offspring development time and pupal mass did not differ between the nutrient treatments. Offspring survival of C. milii showed a monotonic non‐linear increase with decreasing plant stress intensity. These results clearly show that an excess of nutrients may result in plant stress and reduced herbivore performance. 相似文献
22.
Soo-Kyung Lim Jean-Pascal de Bandt Christian Aussel Pascal Pernet Jacqueline Giboudeau Luc Cynober 《Journal of cellular physiology》1995,162(3):422-426
This study investigates the short-tem effects of glucagon and human recombinant tumor necrosis factor α (TNFα) singly and in association on 2-methylaminoisobutyric acid (MeAIB) transport in hepatocyte monolayers. As expected, glucagon induced a time-dependent stimulation of MeAIB transport. In our experimental conditions, TNFα did not induce cytolysis. A 2 hour exposure to TNFα (0.05–500 ng/I) with or without glucagon (10?9 to 10?6 M) did not modify the basal or glucagon-stimulated MeAIB transport. Varying the duration of exposure to TNFα 5 ng/I up to 6 h was equally ineffective. The presence of hydrocortisone potentiated the glucagon-stimulated transport, but TNFα remained ineffective. Finally, the association of interferon (IFNγ) with TNFα and/or glucagon was unable to modify the transport activity. These data demonstrate that TNFα does not exert a direct effect on MeAIB transport in hepatocytes, at least on a short-term basis. © 1995 Wiley-Liss, Inc. 相似文献
23.
On potentials and relevance of the use of copulatory structures in anostracan taxonomy 总被引:1,自引:1,他引:0
This paper reviews and extends the knowledge of anostracan penile morphology and its taxonomic significance. Since Linder‘s
pioneering classification(based partly on male genital characters), the morphology of both basal and distal penile parts has
been applied repeatedly to reorganize or establish higher anostracan taxa, or to extend their diagnoses. In general, the configuration
of both basal and distal penile structures follows a constant pattern in well-defined genera. Size and shape of processes
and spinulation on the basal (in Linderiella and Chirocephalidae) and the distal parts (in Parartemia), however, may show
inter-specific differences. Variability in penile structures in the current genus Brachinella indicates the need for a taxonomic
revision of this genus. Similar intra-generic penis morphology may contribute to hybridizability of congeners and validate
Dubois‘genus concept for use in anostracans.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
24.
Gosselin Luc E.; Megirian David; Rodman Joshua; Mueller Donna; Farkas Gaspar A. 《Journal of applied physiology》1997,83(4):1405
Gosselin, Luc E., David Megirian, Joshua Rodman, DonnaMueller, and Gaspar A. Farkas. Respiratory muscle reserve in ratsduring heavy exercise. J. Appl.Physiol. 83(4): 1405-1409, 1997.The extent towhich the respiratory pump muscles limit maximal aerobic capacity inquadrupeds is not entirely clear. To examine the effect of reducedrespiratory muscle reserve on aerobic capacity, whole bodypeak oxygen consumption(O2 peak) wasmeasured in healthy Sprague-Dawley rats before and after Sham,unilateral, or bilateral hemidiaphragm denervation (Dnv) surgery.O2 peak wasdetermined by using a graded treadmill running test.Hemidiaphragm paralysis was verified after testing byrecording the absence of electromyographic activity duringinspiration. Before surgery, O2 peak averaged 86, 87, and 92 ml · kg1 · min1for the Sham, unilateral, and bilateral Dnv groups, respectively. Twoweeks after surgery, there was no significant change inO2 peak foreither the Sham or unilateral Dnv group. However,O2 peak decreased~19% in the bilateral Dnv group 2 wk after surgery. These findingsstrongly suggest that the pulmonary system in rats is designed suchthat during heavy exercise, the remaining respiratory pump muscles areable to compensate for the loss of one hemidiaphragm, but not of both. 相似文献
25.
In vitro colonization ability of human colon mucosa by exogenous Lactobacillus strains 总被引:1,自引:0,他引:1
Leila-ouassila Sarem-Damerdji Farzin Sarem Luc Marchal Jean-Pierre Nicolas 《FEMS microbiology letters》1995,131(2):133-137
Abstract A 5.4 kb Hind III DNA fragment carrying the gene encoding raw starch-digesting α-amylase (RSDA), has been previously cloned from Bacillus circulans F-2 and expressed in Escherichia coli [Kim et al. (1990) Biochim. Biophys. Acta 1048, 2233–2238]. Interestingly, when the cell extract of E. coli harboring a plasmid carrying this fragment was incubated with l M NaCl, it exhibited about 10 times higher enzyme activity than when assayed without NaCl. Differential zymograms showed two different amylase activities: one for RSDA and the other for a salt-dependent a-amylase (SDA). Even though RSDA activity was detected without NaCl, SDA activity was detected only in high concentrations of NaCl. SDA activity was fully detected at above l M NaCl. Results from subcloning of the genes, fractionation analysis of cell extracts, and immunological assays clearly suggested that the two amylases are genetically distinct and that genes for both enzymes are closely linked on the 5.4 kb DNA fragment. 相似文献
26.
Luc Cynober Jean-Louis Auget Jean Agneray Ohvanesse G. Ekindjian 《Biochemical and biophysical research communications》1984,123(2):535-542
2-deoxyglucose uptake rates at low sugar concentrations (less than 500 μM) appeared to be lower than those predicted by the Michaelis-Menten model which correctly described higher concentrations. This phenomenon which we will call concentration-dependent transport lag, was also observed for L-glucose uptake which suggest that this phenomenon is carrier-independent. A model involving the perimembrane space is developed which, for L-glucose, gives k1 = 0.931 ± 0.072 × 10?6 l. mg protein?1. minute?1, k2 = 2.97 ± 0.19 × 10?7 l. mg protein?1. minute?1 and So = 88,8 ± 4,3 μM; where k1 is the diffusion constant in the cell membrane, k2 is the diffusion constant in the perimembrane space and So the sugar concentration required in the external medium in order to provide an équivalent sugar concentration in the transport carrier area. 相似文献
27.
28.
Juan Ortín Concepción Martínez Lucía del Río Mercedes Dávila Cecilio López-Galíndez Nieves Villanueva Esteban Domingo 《Gene》1983,23(2):233-239
The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/ (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences. 相似文献
29.
Pyrolytic Methylation-Gas Chromatography of Whole Bacterial Cells for Rapid Profiling of Cellular Fatty Acids 下载免费PDF全文
A novel, on-line derivatization technique has been developed which enables generation of fatty acid methyl ester (FAME) profiles from microorganisms by gas chromatography-mass spectrometry without the need for laborious and time-consuming sample preparation. Microgram amounts of bacterial cells are directly applied to a thin ferromagnetic filament and covered with a single drop of methanolic solution of tetramethylammonium hydroxide. After air drying, the filament is inserted into a special gas chromatograph inlet equipped with a high-frequency coil, thus enabling rapid inductive heating of the ferromagnetic filament. This so-called Curie-point heating technique is shown to produce patterns of bacterial FAMEs which are qualitatively and quantitatively nearly identical to those obtained from extracts of methylated lipids prepared by conventional sample pretreatment methods. Relatively minor differences involve the loss of hydroxy-substituted fatty acids by the pyrolytic approach as well as strongly enhanced signals of FAMEs derived from mycolic acids. This type of pyrolysis enables on-line derivatization and thermal extraction of volatile derivatives for analysis, whereas the residual components remain on a disposable probe (ferromagnetic wire) of a pyrolytic device. The reduced sample size (micrograms instead of milligrams) and the lack of sample preparation requirements open up the possibility of rapid microbiological identification of single colonies (thus overcoming the need for time-consuming subculturing) as well as analysis of FAME profiles directly from complex environmental samples. 相似文献
30.