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101.
Nakashima H Terabe M Berzofsky JA Husain SR Puri RK 《Journal of immunology (Baltimore, Md. : 1950)》2011,187(10):4935-4946
Optimum efficacy of therapeutic cancer vaccines may require combinations that generate effective antitumor immune responses, as well as overcome immune evasion and tolerance mechanisms mediated by progressing tumor. Previous studies showed that IL-13Rα2, a unique tumor-associated Ag, is a promising target for cancer immunotherapy. A targeted cytotoxin composed of IL-13 and mutated Pseudomonas exotoxin induced specific killing of IL-13Rα2(+) tumor cells. When combined with IL-13Rα2 DNA cancer vaccine, surprisingly, it mediated synergistic antitumor effects on tumor growth and metastasis in established murine breast carcinoma and sarcoma tumor models. The mechanism of synergistic activity involved direct killing of tumor cells and cell-mediated immune responses, as well as elimination of myeloid-derived suppressor cells and, consequently, regulatory T cells. These novel results provide a strong rationale for combining immunotoxins with cancer vaccines for the treatment of patients with advanced cancer. 相似文献
102.
Redox signaling: thiol chemistry defines which reactive oxygen and nitrogen species can act as second messengers 总被引:10,自引:0,他引:10
Except for the role of NO in the activation of guanylate cyclase, which is well established, the involvement of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in signal transduction remains controversial, despite a large body of evidence suggestive of their participation in a variety of signaling pathways. Several problems have limited their acceptance as signaling molecules, with the major one being the difficulty in identifying the specific targets for each pathway and the chemical reactions supporting reversible oxidation of these signaling components, consistent with a second messenger role for ROS and RNS. Nevertheless, it has become clear that cysteine residues in the thiolate (i.e., ionized) form that are found in some proteins can be specific targets for reaction with H2O2 and RNS. This review focuses on the chemistry of the reversible oxidation of those thiolates, with a particular emphasis on the critical thiolate found in protein tyrosine phosphatases as an example. hydrogen peroxide; thiolate; nitrosothiol; nitric oxide; signal transduction 相似文献
103.
Development of a technology for commercial phytoextraction of nickel: economic and technical considerations 总被引:10,自引:2,他引:10
Li Yin-M. Chaney Rufus Brewer Eric Roseberg Richard Angle J. Scott Baker Alan Reeves Roger Nelkin Jay 《Plant and Soil》2003,249(1):107-115
In recent R&D work, we have made progress in developing a commercial technology using hyperaccumulator plant species to phytoextract nickel (Ni) from contaminated and/or Ni-rich soils. An on-going program is being carried out to develop a genetically improved phytoextraction plant that combines favorable agronomic and Ni accumulation characteristics. Genetically diverse Ni hyperaccumulator species and ecotypes of Alyssum were collected and then evaluated in both greenhouse and field using serpentine and Ni-refinery contaminated soils. Large genetic variation was found in those studies. Mean shoot Ni concentrations in field-grown plants ranged from 4200 to 20400 mg kg–1. We have been studying several soil management practices that may affect the efficiency of Ni phytoextraction. Soil pH is an important factor affecting absorption of metals by plants. An unexpected result of both greenhouse and field experiments was that Ni uptake by two Alyssum species was reduced at lower soil pH and increased at higher soil pH. At higher pH, plant yield was improved also. In soil fertility management studies, we found that N application significantly increased plant biomass, but did not affect plant shoot Ni concentration. These findings indicate that soil management will be important for commercial phytoextraction. A number of field trials have been carried out to study planting methods, population density, weed control practices, harvest schedule and methods, pollination control, and seed processing. Such crop management studies have improved phytoextraction efficiency and provide a tool for farmers to conduct commercial production. We have done some work to develop efficient and cost-effective methods of Ni recovery. Recovery of energy by biomass burning or pyrolysis could help make phytoextraction more cost-effective. The progress made in our recent studies will enable us to apply this technology commercially in the near future. 相似文献
104.
Responses in stomatal conductance to elevated CO2 in 12 grassland species that differ in growth form
Responses in stomatal conductance (g
st
) and leaf xylem pressure potential (
leaf
) to elevated CO2 (2x ambient) were compared among 12 tallgrass prairie species that differed in growth form and growth rate. Open-top chambers (OTCs, 4.5 m diameter, 4.0 m in height) were used to expose plants to ambient and elevated CO2 concentrations from April through November in undisturbed tallgrass prairie in NE Kansas (USA). In June and August,
leaf
was usually higher in all species at elevated CO2 and was lowest in adjacent field plots (without OTCs). During June, when water availability was high, elevated CO2 resulted in decreased g
st
in 10 of the 12 species measured. Greatest decreases in g
st
(ca. 50%) occurred in growth forms with the highest potential growth rates (C3 and C4 grasses, and C3 ruderals). In contrast, no significant decrease in g
st
was measured in the two C3 shrubs. During a dry period in September, reductions in g
st
at elevated CO2 were measured in only two species (a C3 ruderal and a C4 grass) whereas increased g
st
at elevated CO2 was measured in the shrubs and a C3 forb. These increases in g
st
were attributed to enhanced
leaf
in the elevated CO2 plants resulting from increased soil water availability and/or greater root biomass. During a wet period in September, only reductions in g
st
were measured in response to elevated CO2. Thus, there was significant interspecific variability in stomatal responses to CO2 that may be related to growth form or growth rate and plant water relations. The effect of growth in the OTCs, relative to field plants, was usually positive for g
st
and was greatest (>30%) when water availability was low, but only 6–12% when
leaf
was high.The results of this study confirm the importance of considering interactions between indirect effects of high CO2 of plant water relations and direct effects of elevated CO2 on g
st
, particularly in ecosystems such as grasslands where water availability often limits productivity. A product of this interaction is that the potential exists for either positive or negative responses in g
st
to be measured at elevated levels of CO2. 相似文献
105.
106.
Molecular mechanisms underlying the emergence of bacterial pathogens: an ecological perspective 下载免费PDF全文
The rapid emergence of new bacterial diseases negatively affects both human health and agricultural productivity. Although the molecular mechanisms underlying these disease emergences are shared between human‐ and plant‐pathogenic bacteria, not much effort has been made to date to understand disease emergences caused by plant‐pathogenic bacteria. In particular, there is a paucity of information in the literature on the role of environmental habitats in which plant‐pathogenic bacteria evolve and on the stress factors to which these microbes are unceasingly exposed. In this microreview, we focus on three molecular mechanisms underlying pathogenicity in bacteria, namely mutations, genomic rearrangements and the acquisition of new DNA sequences through horizontal gene transfer (HGT). We briefly discuss the role of these mechanisms in bacterial disease emergence and elucidate how the environment can influence the occurrence and regulation of these molecular mechanisms by directly impacting disease emergence. The understanding of such molecular evolutionary mechanisms and their environmental drivers will represent an important step towards predicting bacterial disease emergence and developing sustainable management strategies for crops. 相似文献
107.
Occurrence and Characterization of the Bacterial Spot Pathogen Xanthomonas euvesicatoria on Pepper in Iran 下载免费PDF全文
Ebrahim Osdaghi S. Mohsen Taghavi Habiballah Hamzehzarghani Jay Ram Lamichhane 《Journal of Phytopathology》2016,164(10):722-734
We report in this study for the first time the occurrence of bacterial spot of pepper in Iran and both phenotypic and genetic characterization of its causal agent, Xanthomonas euvesicatoria. Pepper plants grown in 15 of 30 surveyed private gardens and commercial fields were infected by the pathogen in Marand County, East Azerbaijan Province, north‐western Iran. The obtained strains of X. euvesicatoria had different amylolytic and pectolytic activities compared with those reported for this species elsewhere. Pathogenicity tests showed that strains isolated from diseased pepper are able to infect tomato, in addition to pepper. Host range of the pathogen was assessed on eight annual plant species including crops and weeds by measuring the population dynamics. The host range assessment showed that in addition to pepper and tomato, known hosts of X. euvesicatoria, the Iranian strains were able to colonize a number of new hosts such as nightshade and common bean. In contrast, none of them were able to build up their population on cowpea, eggplant, bindweed and zucchini. All X. euvesicatoria strains obtained in this study were sensitive to copper sulphate and streptomycin at concentrations higher than 20 and 50 mg/l, respectively. Phylogenetic analyses of the strains using the sequences of gyrB and hrpB genes confirmed their species as X. euvesicatoria. Given a direct commercial trade of fresh solanaceous vegetables between Iran and Turkey, it is hypothesized that the pathogen entered north‐western Iran from eastern parts of Turkey through infected plant materials. Finally, the role of prevention – based on the use of healthy planting materials and resistant and/or tolerant plant varieties – to contain the potential disease epidemics is discussed. 相似文献
108.
DISTRIBUTION AND ABUNDANCE OF THE AMAZON RIVER DOLPHIN (INIA GEOFFRENSIS) AND THE TUCUXI (SOTALIA FLUVIATILIS) IN THE UPPER AMAZON RIVER 总被引:1,自引:0,他引:1
Omar Vidal Jay Barlow Luis A. Hurtado Jorge Torre Patricia Cendón Zully Ojeda 《Marine Mammal Science》1997,13(3):427-445
A boat survey was conducted from 5 to 26 June 1993 to estimate the abundance of the Amazon river dolphin ( Inia geoffrensis ) and the tucuxi ( Sotalia fluviatilis ) along ca . 120 km of the Amazon River bordering Colombia, Peru, and Brazil. Two survey methods were used: line transects during 5 d and strip transects during 15 d. The line transects were used to estimate the abundance of both species in the main channels of the Amazon at distances greater than 200 m from river banks and islands, and strip transects were used to estimate abundance in the remainder of the habitat. A total of 29 sightings was obtained using line transects, including 8 of Inia , 15 of Sotalia , and 6 with both species present. The total number of sightings made while using strip transects was 143, including 78 of Inia , 51 of Sotalia , and 14 with both species present. The distributions of sightings with respect to distance from the nearest bank were not significantly different between the two species. Based on the results from the two methods, we estimate that there are 346 (CV = 0.12) Inia and 409 (CV = 0.13) Sotalia in the study area. Overall, the mean group size for Inia was 2.9 individuals and for Sotalia was 3.9 individuals. Inia density (dolphin/km2 ) was highest in tributaries (4.8), followed by areas around islands (2.7) and along main banks (2.0); while Sotalia density was highest in lakes (8.6), followed by areas along main banks (2.8) and around islands (2.0). These are among the highest densities measured to date for any cetacean. 相似文献
109.
Vincent E. Sollars Ed Pequignot Jay L. Rothstein Arthur M. Buchberg 《Mammalian genome》2006,17(8):808-821
The myeloid progenitor cell compartment (MPC) exhibits pronounced expansion in human myeloid leukemias. It is becoming more
apparent that progression of myelodysplastic syndromes and myeloproliferative diseases to acute myelogenous leukemia is the
result of defects in progenitor cell maturation. The MPC of bone marrow was analyzed in mice using a cell culture assay for
measuring the relative frequency of proliferative myeloid progenitors. Response to the cytokines SCF, IL-3, and GM-CSF was
determined by this assay for the leukemic mouse strain BXH-2 and ten other inbred mouse strains. Significant differences were
found to exist among ten inbred mouse strains in the nature of their MPC in bone marrow, indicating the presence of genetic
polymorphisms responsible for the divergence. The SWR/J and FVB/J strains show consistently low frequencies of myeloid progenitors,
while the DBA/2J and SJL/J inbred strains show consistently high frequencies of myeloid progenitors within the bone marrow
compartment. In addition, in silico linkage disequilibrium analysis was conducted to identify possible chromosomal regions responsible for the phenotypic variation.
Given the importance of this cell compartment in leukemia progression and the soon to be released genomic sequence of 15 mouse
strains, these differences may provide a valuable tool for research into leukemia. 相似文献
110.
Tumor necrosis factor-induced toxic liver injury results from JNK2-dependent activation of caspase-8 and the mitochondrial death pathway 总被引:11,自引:0,他引:11
Wang Y Singh R Lefkowitch JH Rigoli RM Czaja MJ 《The Journal of biological chemistry》2006,281(22):15258-15267
In vitro studies of hepatocytes have implicated over-activation of c-Jun N-terminal kinase (JNK) signaling as a mechanism of tumor necrosis factor-alpha (TNF)-induced apoptosis. However, the functional significance of JNK activation and the role of specific JNK isoforms in TNF-induced hepatic apoptosis in vivo remain unclear. JNK1 and JNK2 function was, therefore, investigated in the TNF-dependent, galactosamine/lipopolysaccharide (GalN/LPS) model of liver injury. The toxin GalN converted LPS-induced JNK signaling from a transient to prolonged activation. Liver injury and mortality from GalN/LPS was equivalent in wild-type and jnk1-/- mice but markedly decreased in jnk2-/- mice. This effect was not secondary to down-regulation of TNF receptor 1 expression or TNF production. In the absence of jnk2, the caspase-dependent, TNF death pathway was blocked, as reflected by the failure of caspase-3 and -7 and poly(ADP-ribose) polymerase cleavage to occur. JNK2 was critical for activation of the mitochondrial death pathway, as in jnk2-/- mice Bid cleavage and mitochondrial translocation and cytochrome c release were markedly decreased. This effect was secondary to the failure of jnk2-/- mice to activate caspase-8. Liver injury and caspase activation were similarly decreased in jnk2 null mice after GalN/TNF treatment. Ablation of jnk2 did not inhibit GalN/LPS-induced c-Jun kinase activity, although activity was completely blocked in jnk1-/- mice. Toxic liver injury is, therefore, associated with JNK over-activation and mediated by JNK2 promotion of caspase-8 activation and the TNF mitochondrial death pathway through a mechanism independent of c-Jun kinase activity. 相似文献