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991.
Rhainds M Cloutier C Shipp L Boudreault S Daigle G Brodeur J 《Environmental entomology》2007,36(2):475-483
Modeling the effect of temperature on the sustainability of insect-plant interactions requires assessment of both insect and plant performance. We examined the effect of temperature on western flower thrips, Frankliniella occidentalis (Pergande), a generalist herbivore with a high reproductive rate, and chrysanthemum inflorescences, a high quality but relatively fixed, ephemeral resource for thrips population growth. We hypothesized that different thrips versus plant responses to temperature result in significant statistical interaction of temperature with thrips abundance and flower damage attributes over time. Experiments were conducted at five temperatures between 20.7 and 35.3 degrees C, with thrips infestation and time after infestation as main effects. Only minor, uncontrolled variations in relative humidity and light intensity may otherwise have influenced the results. High temperatures lead to an initially rapid increase in density of thrips followed by abrupt declines in abundance. The rate of floral senescence increased with temperature and thrips infestation, as indicated by a reduced fresh biomass and greater leaching of yellow pigments. Multiple regression indicated that indices of plant damage responded more directly to thrips density at low than high temperature, supporting the conclusion that temperature affected the outcome beyond what was predictable simply from differential plant and insect optima. The relative intensity of damage caused by individual thrips decreased with increasing temperature, likely caused by thrips competition and reduced survival, growth, and fecundity on depleted inflorescences. Reduced per capita damage at high temperature may be common in insects exploiting fixed plant resources that exhibit an accelerated rate of deterioration at high temperatures. 相似文献
992.
Held B Tsvilovskyy V Meissner M Kaestner L Ludwig A Mossmang S Lipp P Freichel M Flockerzi V 《Cell calcium》2007,42(4-5):477-487
Voltage activated L-type Ca(2+) channels are the principal Ca(2+) channels in intestinal smooth muscle cells. They comprise the ion conducting Ca(V)1 pore and the ancillary subunits alpha(2)delta and beta. Of the four Ca(V)beta subunits Ca(V)beta(3) is assumed to be the relevant Ca(V)beta protein in smooth muscle. In protein lysates isolated from mouse ileum longitudinal smooth muscle we could identify the Ca(V)1.2, Ca(V)alpha(2), Ca(V)beta(2) and Ca(V)beta(3) proteins, but not the Ca(V)beta(1) and Ca(V)beta(4) proteins. Protein levels of Ca(V)1.2, Ca(V)alpha(2) and Ca(V)beta(2) are not altered in ileum smooth muscle obtained from Ca(V)beta(3)-deficient mice indicating that there is no compensatory increase of the expression of these channel proteins. Neither the Ca(V)beta(2) nor the other Ca(V)beta proteins appear to substitute for the lacking Ca(V)beta(3). L-type Ca(2+) channel properties including current density, inactivation kinetics as well as Cd(2+)- and dihydropyridine sensitivity were identical in cells of both genotypes suggesting that they do not require the presence of a Ca(V)beta(3) protein. However, a key hallmark of the Ca(V)beta modulation of Ca(2+) current, the hyperpolarisation of channel activation is slightly but significantly reduced by 4 mV. In addition to L-type Ca(2+) currents T-type Ca(2+) currents could be recorded in the murine ileum smooth muscle cells, but T-type currents were not affected by the lack of Ca(V)beta(3). Both proteins, Ca(V)beta(2) and Ca(V)beta(3) are localized near the plasma membrane and the localization of Ca(V)beta(2) is not altered in Ca(V)beta(3) deficient cells. Spontaneous contractions and potassium and carbachol induced contractions are not significantly different between ileum longitudinal smooth muscle strips from mice of both genotypes. In summary the data show that in ileum smooth muscle cells, Ca(V)beta(3) has only subtle effects on L-type Ca(2+) currents, appears not to be required for spontaneous and potassium induced contraction but might have a function beyond being a Ca(2+) channel subunit. 相似文献
993.
Mareuil F Sizun C Perez J Schoenauer M Lallemand JY Bontems F 《European biophysics journal : EBJ》2007,37(1):95-104
Most proteins comprise several domains and/or participate in functional complexes. Owing to ongoing structural genomic projects,
it is likely that it will soon be possible to predict, with reasonable accuracy, the conserved regions of most structural
domains. Under these circumstances, it will be important to have methods, based on simple-to-acquire experimental data, that
allow to build and refine structures of multi-domain proteins or of protein complexes from homology models of the individual
domains/proteins. It has been recently shown that small angle X-ray scattering (SAXS) and NMR residual dipolar coupling (RDC)
data can be combined to determine the architecture of such objects when the X-ray structures of the domains are known and
can be considered as rigid objects. We developed a simple genetic algorithm to achieve the same goal, but by using homology
models of the domains considered as deformable objects. We applied it to two model systems, an S1KH bi-domain of the NusA
protein and the γS-crystallin protein. Despite its simplicity our algorithm is able to generate good solutions when driven
by SAXS and RDC data. 相似文献
994.
Horner KC Cazals Y Guieu R Lenoir M Sauze N 《American journal of physiology. Endocrinology and metabolism》2007,293(5):E1224-E1232
Our group (Horner KC, Guieu R, Magnan J, Chays A, Cazals Y. Neuropsychopharmacology 26: 135-138, 2002) has earlier described hyperprolactinemia in some patients presenting inner ear dysfunction. However, in that study, it was not possible to determine whether hyperprolactinemia was a cause or an effect of the symptoms. To investigate the effect of hyperprolactinemia on inner ear function, we first developed a model of hyperprolactinemia in estrogen-primed Fischer 344 rats and then performed functional studies on pigmented guinea pigs. Hyperprolactinemia induced, after 2 mo, a hearing loss of approximately 30-40 dB across all frequencies, as indicated by the compound action potential audiogram. During the 3rd mo, the hearing loss continued to deteriorate. The threshold shifts were more substantial in males than in females. Observations under a dissection microscope revealed bone dysmorphology of the bulla and the cochlea. Light microscopy observations of cryostat sections confirmed bone-related pathology of the bony cochlear bulla and the cochlear wall and revealed morphopathology of the stria vascularis and spiral ligament. Scanning electron microscopy revealed loss of hair cells and stereocilia damage, in particular in the upper three cochlear turns and the two outermost hair cell rows. The data provide the first evidence of otic capsule and hair cell pathology associated with estrogen-induced prolonged hyperprolactinemia and suggest that conditions such as pregnancy, anti-psychotic drug treatment, aging, and/or stress might lead to similar ear dysfunctions. 相似文献
995.
Inhibitory effect of a defensin gene from the Andean crop maca (Lepidium meyenii) against Phytophthora infestans 总被引:1,自引:0,他引:1
In this study, we report the isolation of a defensin gene, lm-def, isolated from the Andean crop 'maca' (Lepidium meyenii) with activity against the pathogen Phytophthora infestans responsible of late blight disease of the potato and tomato crops. The lm-def gene has been isolated by polymerase chain reaction (PCR) using degenerate primers corresponding to conserved regions of 13 plant defensin genes of the Brassicaceae family assuming that defensin genes are highly conserved among cruciferous species. The lm-def gene belongs to a small multigene family of at least 10 members possibly including pseudogenes as assessed by genomic hybridization and nucleotide sequence analyses. The deduced mature Lm-Def peptide is 51 amino acids in length and has 74-94% sequence identity with other plant defensins of the Brassicaceae family. The Lm-Def peptide was produced as a fusion protein using the pET-44a expression vector and purified using an immobilized metal ion affinity chromatography. The recombinant protein (NusA:Lm-Def) exhibited in vitro activity against P. infestans. The NusA:Lm-Def protein caused growth inhibition and hyphal damage at concentration not greater than 0.4 microM. In contrast, the NusA protein alone expressed and purified similarly did not show any activity against P. infestans. Therefore, these results indicate that the lm-def gene isolated from maca belong to the plant defensin family with activity against P. infestans. Its expression in potato, as a transgene, might help to control the late blight disease caused by P. infestans with the advantage of being of plant origin. 相似文献
996.
997.
Jacobsen M Detjen AK Mueller H Gutschmidt A Leitner S Wahn U Magdorf K Kaufmann SH 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(2):1331-1339
The role of CD8(+) T cells in human tuberculosis (TB) remains elusive. We analyzed the T cell repertoire and phenotype in 1) children with active TB (< or =4 years), 2) healthy latently Mycobacterium tuberculosis-infected children, and 3) noninfected age-matched (tuberculin skin test-negative) controls. Ex vivo phenotyping of T cell subpopulations by flow cytometry revealed a significant increase in the proportion of CD8(+)CD45RO(-)CD62L(-)CD28(-)CD27(-) effector T cells (T(EF)) in the peripheral blood of children with active TB (22.1 vs 9.5% in latently M. tuberculosis-infected children, vs 8.5% in tuberculin skin test-negative controls). Analyses of TCR variable beta-chains revealed markedly skewed repertoires in CD8(+) T(EF) and effector memory T cells. Expansions were restricted to single TCR variable beta-chains in individual donors indicating clonal growth. CDR3 spectratyping and DNA sequencing verified clonal expansion as the cause for CD8(+) effector T cell enrichment in individual TB patients. The most prominent enrichment of highly similar T(EF) clones (>70% of CD8(+) T(EF)) was found in two children with active severe TB. Therefore, clonal expansion of CD8(+) T(EF) occurs in childhood TB with potential impact on course and severity of disease. 相似文献
998.
Simson L Ellyard JI Dent LA Matthaei KI Rothenberg ME Foster PS Smyth MJ Parish CR 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(7):4222-4229
The role of the immune system in the surveillance of transformed cells has seen a resurgence of interest in the last 10 years, with a substantial body of data in mice and humans supporting a role for the immune system in host protection from tumor development and in shaping tumor immunogenicity. A number of earlier studies have demonstrated that eosinophils, when recruited into tumors, can very effectively eradicate transplantable tumors. In this study, we investigated whether eosinophils also play a role in tumor immune surveillance by determining the incidence of methylcholanthrene (MCA)-induced fibrosarcomas in IL-5 transgenic mice that have greatly enhanced levels of circulating eosinophils, CCL11 (eotaxin-1)-deficient mice that lack a key chemokine that recruits eosinophils into tissues, and the eosinophil-deficient mouse strains, IL-5/CCL11(-/-) and DeltadblGATA. It was found that MCA-induced tumor incidence and growth were significantly attenuated in IL-5 transgenic mice of both the BALB/c and C57BL/6 backgrounds. Histological examination revealed that the protective effect of IL-5 was associated with massively enhanced numbers of eosinophils within and surrounding tumors. Conversely, there was a higher tumor incidence in CCL11(-/-) BALB/c mice, which was associated with a reduced eosinophil influx into tumors. This correlation was confirmed in the eosinophil-deficient IL-5/CCL11(-/-) and DeltadblGATA mouse strains, where tumor incidence was greatly increased in the total absence of eosinophils. In addition, subsequent in vitro studies found that eosinophils could directly kill MCA-induced fibrosarcoma cells. Collectively, our data support a potential role for the eosinophil as an effector cell in tumor immune surveillance. 相似文献
999.
Müller V Viemann D Schmidt M Endres N Ludwig S Leverkus M Roth J Goebeler M 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(12):8435-8445
1000.
Aronoff DM Peres CM Serezani CH Ballinger MN Carstens JK Coleman N Moore BB Peebles RS Faccioli LH Peters-Golden M 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(3):1628-1634
PGI(2) (prostacyclin) is a lipid mediator with vasodilatory and antithrombotic effects used in the treatment of vasoconstrictive/ischemic diseases including pulmonary artery hypertension. However, emerging research supports a role for PGs, including PGI(2), in the regulation of both innate and acquired immunity. As PGI(2) is unstable, we sought to define the effects of various PGI(2) analogs on resident alveolar macrophage (AM) and peritoneal macrophage (PM) innate immune functions. The effects of iloprost, carbaprostacyclin, and treprostinil on the regulation of phagocytosis, bacterial killing, and inflammatory mediator production were determined in both macrophage populations from rats. Iloprost failed to suppress AM functions to the same degree that it did in PMs, a characteristic shared by carbaprostacyclin. This difference reflected greater expression of the G(alphas) protein-coupled I prostanoid receptor and greater cAMP generation in PMs than AMs. Treprostinil inhibited phagocytosis, bacterial killing, and cytokine generation in AMs to a much greater degree than the other PGI(2) analogs and more closely resembled the effects of PGE(2). Studies with the E prostanoid (EP) 2 receptor antagonist AH-6809 and EP2-null macrophages indicated that this was due in part to the previously unknown ability of treprostinil to stimulate the EP2 receptor. The present investigation for the first time identifies differences in immunoregulatory properties of clinically administered PGI(2) analogs. These studies are the first to explore the capacity of PGI(2) to regulate bacterial killing and phagocytosis in macrophages, and our findings may hold important consequences regarding the risk of infection for patients receiving such agents. 相似文献