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131.
132.
P S Duffey O A Lukasewycz D Martinez W H Murphy 《Journal of immunology (Baltimore, Md. : 1950)》1976,116(5):1332-1336
Terminal dilution, adoptive cell transfer techniques were developed to quantify the protective effect of lymphoid cells in the pathogenesis of immune polioencephalomyelitis (IPE). The pathogenic effects of lymphoid cell populations were quantified by deleting the step of antigenic challenge. Regression curves were computer analyzed and PD50 values were compared. Immune spleen cells (ISC) from 4- to 6-week-old donors were more protective (PD50 = 4.9 +/- 1.3) than ISC from 12-month-old animals (PD50 greater than 7.0). The slopes of the regression curves also differed markedly (young mice, -0.24; old mice, -0.09). ISC were less protective in 12-month-indicator mice than in 5-month-old recipients (PD50 values of 5.2 +/- 0.8 and 3.7 +/- 0.8, respectively). When adoptive cell transfer tests were used to quantify the pathogenetic effects of donor cells it was found that ISC were pathogenetic at doses of 10(5) or less, but protective at higher doses. IPEC were pathogenetic at all test doses. When ISC were x-irradiated or sonicated the were only pathogenetic. Normal spleen or peritoneal exudate cells were neither protective nor pathogenetic. A model was developed in which mice were either thymectomized at birth (Tx), or Tx at birth and x-irradiated (500 R) 8 weeks later (Tx-XR). Sham Tx or Tx-XR mice served as controls. All of the mice were challenged with antigen (10(4) x-irradiated Ib cells). Only a portion (8/24) of the Tx mice developed IPE, indicating that resistance was T cell dependent but also involved a significant T cell independent component. The data also indicated that T cells were not pathogenetic effector cells in this model. Tx mice were not reconstituted by ISC (7/18 developed IPE), Tx-XR mice were partially reconstituted (3/12 developed IPE), but sham Tx-XR were fully restored (0/20 had IPE). Normal spleen cells did not reconstitute any of the mice. 相似文献
133.
134.
Sampling along roadsides is convenient and is widely practiced in insect population researches. Ecological conditions in road
verges are very different than those prevailing in natural habitats and they affect the annual growth of plants in semi-arid
and arid regions. This in turn may improve development, survival and abundance of insects feeding on plants growing in roadsides.
These trends may bias the results of sampling. To verify this assertion, we quantified the effects of growing in roadside
on annual growth of Pistacia atlantica trees and Pistacia palaestina shrubs and compare two demographic indexes of nine gall-inducing aphid species on trees growing along roads with trees in
the open landscape, in Israel. The annual growth of the two host plants was significantly more vigorous in roadsides than
away from roads. Tests of Combined Probabilities showed that the likelihood of P. atlantica and P. palaestina to be parasitized by more galls of Fordini species is higher in roadsides than away from roads. Moreover, in the semi-dry
regions of Israel, three aphid species on P. atlantica and five species on P. palaestina induced more galls in plants growing along roads than away from roads, while in the rainy Northern region, the difference
was not significant between the two habitats. These results indicate a biased evaluation of population size in roadside habitat,
which has to be accounted in insect–plant relation researches. 相似文献
135.
136.
C Martinez J M Zumalacarregui V Diez J Burgos 《The International journal of biochemistry》1984,16(12):1279-1282
A low molecular weight form of adenosine deaminase from bovine skeletal muscle was purified about 930-fold. The enzyme had a mol. wt of 31,000, a Km value for adenosine of 2.37 X 10(-5) M and a pH optimum at 7.0. This enzyme is very resistant to heat inactivation and does not require metal activators or other dialysable cofactors. A possible role in the post-mortem metabolism of adenine nucleotide in skeletal muscle is discussed. 相似文献
137.
Riccardo Danielli Roberto Patuzzo Anna Maria Di Giacomo Gianfranco Gallino Andrea Maurichi Annabella Di Florio Ornella Cutaia Andrea Lazzeri Carolina Fazio Clelia Miracco Leonardo Giovannoni Giuliano Elia Dario Neri Michele Maio Mario Santinami 《Cancer immunology, immunotherapy : CII》2015,64(8):999-1009
138.
139.
Surface chemistry and reactivity of bacteriogenic iron oxides from Axial Volcano, Juan de Fuca Ridge, north-east Pacific Ocean 总被引:2,自引:0,他引:2
Iron oxides were collected from the caldera of Axial Volcano, a site of hydrothermal vent activity along the Juan de Fuca Ridge. Mineralogical inspection using X‐ray diffraction (XRD) revealed the majority of samples to be 2‐line ferrihydrite, with one of the samples corresponding to poorly ordered goethite. Examination using environmental scanning electron microscopy (ESEM) found the constituents of the iron oxides to consist predominantly of bacterial‐like structures that resembled the iron oxidizing bacteria Leptothrix ochracea, Gallionella ferruginea and a novel PV‐1 strain. X‐ray photoelectron spectroscopy (XPS) detected the presence of Fe, O, C, N, Ca, Si and P on all the samples with the exception of poorly ordered goethite, where Ca and P were absent, in addition to a weak N peak. Binding energy shifts of the Fe 2p and O 1s peaks were indicative of ferrihydrite and hydroxyl functional groups, while the presence and speciation of the C 1s peak was attributed to the presence of bacteria. Use of acid‐base titration data modelling in conjunction with a linear programming regression method (LPM) indicated that the iron oxides are composed of heterogeneous surface functional groups. Differences in iron oxide reactivity values correlated with differences in the bacterial and mineral fabric of the samples. The diverse surface chemistry and high reactivity of these iron oxides may be important in the global cycling of various elements throughout the oceans due to their presence along widespread mid‐ocean ridges. 相似文献
140.
Leonardo Mata Helena Gaspar Fátima Justino Rui Santos 《Journal of applied phycology》2011,23(5):827-832
The genus Asparagopsis is a prolific source of halogenated metabolites. Due to its commercial applications, it has been intensively cultivated in
southern Portugal. In the present study, we assess if the internal levels of the major halogenated metabolites (bromoform
and dibromoacetic acid) in Asparagopsis taxiformis can be increased with hydrogen peroxide (H2O2) addition. Previous studies with red algae showed that the production/release of bromoform can be enhanced by exogenously
supplying H2O2. However, no study has assessed if H2O2 supply enhances the content of secondary metabolites within the biomass. This detail is important as the objective of the
proposed research is to enhance the content of these valuable metabolites in the produced biomass. Both the activity of the
haloperoxidase enzyme and the metabolite content were assessed on short-term and long-term incubation periods to H2O2. To determine the susceptibility of A. taxiformis photosynthetic performance to the imposed oxidative stress, the in vivo fluorescence of photosystem II was monitored. A. taxiformis was shown to be physiologically vulnerable to H2O2, given the observed decrease of the maximum quantum yield of photosynthesis (F
v/F
m). Contrary to what was expected, the presence of H2O2 inhibited the activity of the iodoperoxidase enzyme. Nevertheless, the extracted halogenated metabolites were higher over
the first hours of exposure to H2O2, decreasing after 48 h. These results are probably related to the prosthetic group of the halogenated enzyme in A. taxiformis and the long-term oxidative stress damage of H2O2 exposure. Considering the objective of the proposed research, addition of H2O2 to the cultures, prior (3 h) to biomass harvesting, increases the metabolite content. 相似文献