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31.
Molecular characterization of salt-stress-associated protein in citrus: protein and cDNA sequence homology to mammalian glutathione peroxidases 总被引:16,自引:0,他引:16
Doron Holland Gozal Ben-Hayyim Zehava Faltin Luc Camoin A. Donny Strosberg Yuval Eshdat 《Plant molecular biology》1993,21(5):923-927
A gene encoding for a citrus salt-stress-associated protein (Cit-SAP) was cloned from Citrus sinensis salt-treated cell suspension. The gene, designated csa, was isolated from a cDNA expression library. The partial amino acid sequence of the protein, as well as that deduced from the nucleotide sequence of csa, revealed a considerable homology to mammalian glutathione peroxidase (GP), and to clone 6P229 from tobacco protoplasts. The increased expression of Cit-SAP in NaCl-treated cultured citrus cells and in citrus plants irrigated with saline water, and its similarity to GP, raise the possibility that one of the effects of salt stress in plants may be the increase of the level of free radicals. 相似文献
32.
We compare the primary sex ratio (proportion of haploid eggs laid by queens) and the secondary sex ratio (proportion of male pupae produced) in the Argentine ant Iridomyrmex humilis with the aim of investigating whether workers control the secondary sex ratio by selectively eliminating male brood. The proportion of haploid eggs produced by queens was close to 0.5 in late winter, decreased to less than 0.3 in spring and summer, and increased again to a value close to 0.5 in fall. Laboratory experiments indicate that temperture is a proximate factor influencing the primary sex ratio with a higher proportion of haploid eggs being laid at colder temperatures. Production of queen pupae ceased in mid-June, about three weeks before that of male pupae. After this time only worker pupae were produced. During the period of production of sexuals, the proportion of male pupae ranged from 0.30 to 0.38. Outside this period no males were reared although haploid eggs were produced all the year round by queens. Workers thus exert a control on the secondary sex ratio by eliminating a proportion of the male brood during the period of sexual production and eliminating all the males during the remainder of the cycle. These data are consistent with workers preferring a more female-biased sex ratio than queens. The evolutionary significance of the production of male eggs by queens all the year round is as yet unclear. It may be a mechanism allowing queen replacement in the case of the death of the queens in the colony. 相似文献
33.
34.
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
35.
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
36.
Damgaard P.H. Abdel-Hameed A. Eilenberg J. Smits P.H. 《World journal of microbiology & biotechnology》1997,14(2):239-242
World Journal of Microbiology and Biotechnology - 相似文献
37.
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
38.
Polymerase C1 levels and poly(R-3-hydroxyalkanoate) synthesis in wild-type and recombinant Pseudomonas strains.
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A functional antibody highly specific for polymerase C1 of Pseudomonas oleovorans GPo1 was raised and used to determine polymerase C1 levels in in vivo experiments. The polymerase C1 antibodies did not show a cross-reaction with polymerase C2 of P. oleovorans. In wild-type P. oleovorans GPo1 and Pseudomonas putida KT2442, amounts of 0.075 and 0.06% polymerase relative to total protein, respectively, were found. P. oleovorans GPo1(pGEc405), which contained additional copies of the polymerase C1-encoding gene under the control of its native promoter, contained 0.5% polymerase C1 relative to total protein. Polymerase C1 reached 10% of total cell protein when the polymerase C1-encoding gene was overexpressed through the P(alk) promoter in P. oleovorans GPo1(pET702, pGEc74). Amounts of poly(R-3-hydroxyalkanoate) (PHA) increased significantly under non-nitrogen-limiting conditions when additional polymerase C1 was expressed in P. oleovorans. Whereas P. oleovorans produced 34% (wt/wt) PHA under these conditions, a PHA level of 64% (wt/wt) could be reached for P. oleovorans GPo1(pGEc405) and a PHA level of 52% (wt/wt) could be reached for P. oleovorans GPo1(pET702, pGEc74) after induction, compared to a PHA level of 13% for the uninduced control. All recombinant Pseudomonas strains containing additional polymerase C1 showed small changes in their PHA composition. Larger amounts of 3-hydroxyhexanoate monomer and smaller amounts of 3-hydroxyoctanoate and -decanoate were found compared to those of the wild type. Two different methods were developed to quantify rates of incorporation of new monomers into preexisting PHA granules. P. oleovorans GPo1 cells grown under nitrogen-limiting conditions showed growth stage-dependent incorporation rates. The highest PHA synthesis rates of 9.5 nmol of C8/C6 monomers/mg of cell dry weight (CDW)/min were found during the mid-stationary phase, which equals a rate of production of 80 g of PHA/kg of CDW/h. 相似文献
39.
Abstract: The excitatory amino acid glutamate was previously shown to stimulate aerobic glycolysis in astrocytes by a mechanism involving its uptake through an Na+ -dependent transporter. Evidence had been provided that Na+ ,K+ -ATPase might be involved in this process. We have now measured the activity of Na+ ,K+ -ATPase in cultured astrocytes, using ouabain-sensitive 86 Rb uptake as an index. l -Glutamate increases glial Na+ ,K+ -ATPase activity in a concentration-dependent manner with an EC50 = 67 µ M . Both l - and d -aspartate, but not d -glutamate, produce a similar response, an observation that is consistent with an uptake-related effect rather than a receptor-mediated one. Under basal conditions, concentration-dependent inhibition of Na+ ,K+ -ATPase activity in astrocytes by ouabain indicates the presence of a single catalytic site with a low affinity for ouabain ( K 0.5 = 113 µ M ), compatible with the presence of an α1 isozyme. On stimulation with glutamate, however, most of the increased activity is inhibited by low concentrations of ouabain ( K 0.5 = 20 n M ), thus revealing a high-affinity site akin to the α2 isozyme. These results suggest that astrocytes possess a glutamate-sensitive isoform of Na+ ,K+ -ATPase that can be mobilized in response to increased neuronal activity. 相似文献
40.
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