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21.
Thirty mesophilic and thermophilic bacteria were isolated from thermobiotically digested sewage sludge in culture medium supplemented with poly-ε-caprolactone (PCL). The ability of each purified isolate to degrade PCL and to produce polymer-degrading extracellular enzymes was assessed. Isolates were characterized based on random amplified polymorphic DNA (RAPD), 16S rDNA sequence-based phylogenetic affiliation and carbohydrate-based nutritional versatility. Mesophilic isolates with ability to degrade PCL were attributed to the genera Acinetobacter, Burkholderia, Pseudomonas, and Staphylococcus. Thermophilic isolates were members of the genus Bacillus. Despite the restricted phylogenetic and genotypic diversity observed for thermophiles, their metabolic versatility and wide range of growth temperatures suggest an important activity of these organisms during the whole composting process. 相似文献
22.
Antagonistic interaction between abscisic acid and jasmonate-ethylene signaling pathways modulates defense gene expression and disease resistance in Arabidopsis 总被引:15,自引:0,他引:15 下载免费PDF全文
Anderson JP Badruzsaufari E Schenk PM Manners JM Desmond OJ Ehlert C Maclean DJ Ebert PR Kazan K 《The Plant cell》2004,16(12):3460-3479
23.
C Costa L Zhao W V Burton K R Bondioli B L Williams T A Hoagland P A Ditullio K M Ebert W L Fodor 《FASEB journal》1999,13(13):1762-1773
Hyperacute rejection (HAR) is the first critical immunological hurdle that must be addressed in order to develop xenogeneic organs for human transplantation. In the area of cell-based xenotransplant therapies, natural antibodies (XNA) and complement have also been considered barriers to successful engraftment. Transgenic expression of human complement inhibitors in donor cells and organs has significantly prolonged the survival of xenografts. However, expression of complement inhibitors without eliminating xenogeneic natural antibody (XNA) reactivity may provide insufficient protection for clinical application. An approach designed to prevent XNA reactivity during HAR is the expression of human alpha1, 2-fucosyltransferase (H-transferase, HT). H-transferase expression modifies the cell surface carbohydrate phenotype of the xenogeneic cell, resulting in the expression of the universal donor O antigen and a concomitant reduction in the expression of the antigenic Galalpha1,3-Gal epitope. We have engineered various transgenic pig lines that express HT in different cells and tissues, including the vascular endothelium. We demonstrate that in two different HT transgenic lines containing two different HT promoter constructs, expression can be differentially regulated in a constitutive and cytokine-inducible manner. The transgenic expression of HT results in a significant reduction in the expression of the Galalpha1,3-Gal epitope, reduced XNA reactivity, and an increased resistance to human serum-mediated cytolysis. Transgenic pigs that express H-transferase promise to become key components for the development of xenogeneic cells and organs for human transplantation. 相似文献
24.
Dhruv Sareen Erin McMillan Allison D. Ebert Brandon C. Shelley Julie A. Johnson Lorraine F. Meisner Clive N. Svendsen 《PloS one》2009,4(10)
Background
Stem cell expansion and differentiation is the foundation of emerging cell therapy technologies. The potential applications of human neural progenitor cells (hNPCs) are wide ranging, but a normal cytogenetic profile is important to avoid the risk of tumor formation in clinical trials. FDA approved clinical trials are being planned and conducted for hNPC transplantation into the brain or spinal cord for various neurodegenerative disorders. Although human embryonic stem cells (hESCs) are known to show recurrent chromosomal abnormalities involving 12 and 17, no studies have revealed chromosomal abnormalities in cultured hNPCs. Therefore, we investigated frequently occurring chromosomal abnormalities in 21 independent fetal-derived hNPC lines and the possible mechanisms triggering such aberrations.Methods and Findings
While most hNPC lines were karyotypically normal, G-band karyotyping and fluorescent in situ hybridization (FISH) analyses revealed the emergence of trisomy 7 (hNPC+7) and trisomy 19 (hNPC+19), in 24% and 5% of the lines, respectively. Once detected, subsequent passaging revealed emerging dominance of trisomy hNPCs. DNA microarray and immunoblotting analyses demonstrate epidermal growth factor receptor (EGFR) overexpression in hNPC+7 and hNPC+19 cells. We observed greater levels of telomerase (hTERT), increased proliferation (Ki67), survival (TUNEL), and neurogenesis (βIII-tubulin) in hNPC+7 and hNPC+19, using respective immunocytochemical markers. However, the trisomy lines underwent replicative senescence after 50–60 population doublings and never showed neoplastic changes. Although hNPC+7 and hNPC+19 survived better after xenotransplantation into the rat striatum, they did not form malignant tumors. Finally, EGF deprivation triggered a selection of trisomy 7 cells in a diploid hNPC line.Conclusions
We report that hNPCs are susceptible to accumulation of chromosome 7 and 19 trisomy in long-term cell culture. These results suggest that micro-environmental cues are powerful factors in the selection of specific hNPC aneuploidies, with trisomy of chromosome 7 being the most common. Given that a number of stem cell based clinical trials are being conducted or planned in USA and a recent report in PLoS Medicine showing the dangers of grafting an inordinate number of cells, these data substantiate the need for careful cytogenetic evaluation of hNPCs (fetal or hESC-derived) before their use in clinical or basic science applications. 相似文献25.
Tiago F. Carrijo Divino Brandão Danilo E. de Oliveira Diogo A. Costa Thiago Santos 《Journal of Insect Conservation》2009,13(6):575-581
The advance of agricultural frontier may cause the Cerrado (Brazilian savanna) to disappear before 2030. This work focuses
on measuring the impact of pasture implantation on a cerrado’s termite fauna. Termites were sampled in a cerrado sensu stricto
and a pasture, originally cerrado. All species were classified as their feeder group, accumulation curves were made and Shannon-Wiener
indexes and β diversity were calculated for both areas. Cerrado was richer than pasture and species composition differed considerably,
leading β diversity to a high value. The humivorous was the most representative species, followed by grass/litter feeders, xylophagous
and, less representative, the intermediates. There were more xylophagous and intermediates species on cerrado than in pasture;
the grass/litter feeders were more abundant in pasture, but didn’t differed in number or species; and humivorous didn’t differed
neither in richness nor in abundance. This work shows that the simplification of the habitat is indeed causing the extinction
of populations that depend on some specifics resource. 相似文献
26.
Pelz-Stelinski KS Brlansky RH Ebert TA Rogers ME 《Journal of economic entomology》2010,103(5):1531-1541
The purpose of this investigation was to evaluate acquisition and inoculation (together, transmission) efficiency of Candidatus Liberibacter asiaticus (Las), the pathogen associated with citrus huanglongbing (HLB) by the Asian citrus psyllid, Diaphorina citri (Kuwayama) (Hemiptera: Psyllidae). In laboratory studies, nymphs reared on Las infected plants were more likely to acquire the bacterium than adults. Acquisition by nymphs ranged from 60 to 100%, whereas acquisition by adults only reached 40% after 5 wk of feeding on Las-infected plants. Similar rates of pathogen acquisition by psyllids after nymphal and adult feeding were observed in the field. Transmission of Las from parent to offspring (transovarial) occurred at a rate of 2-6%. One year after psyllid inoculations, successful transmission by individual D. citri ranged from 4 to 10%, whereas groups of 100 or more D. citri transmitted the pathogen at a rate of approximately 88%. In addition, the proportion of Las-positive adult psyllids, determined using quantitative real-time polymerase chain reaction, decreased over time when held on healthy plants. Due to the low rate of pathogen acquisition and long time period required for successful inoculation by adult D. citri, experiments designed to determine the latent period required for replication and successful inoculation of Las by D. citri did not result in Las-infected plants after >1 yr of incubation after inoculation. Collectively, these results indicate that adult D. citri which acquire the HLB pathogen as adults are poor vectors of the pathogen compared with adults that acquired the pathogen as nymphs. 相似文献
27.
Abstract The production of porcine growth hormone (pGH) from novel expression vectors containing the promoter/enhancer elements of the Moloney murine leukemia virus (MLV) LTR or the human cytomegalovirus (CMV) immediate early gene was examined in transgenic swine. Both fusion genes resulted in elevated levels of serum pGH, elevation of insulin‐like growth factor 1 (IGF‐1), and a pronounced decrease in carcass fat deposition. The two viral promoter/enhancer elements were constitutively active in the transgenic swine throughout the life of the animals. In individual swine, the CMV‐pGH transgene was expressed predominantly in the pancreas while the MLV‐pGH transgene was expressed in a wide variety of tissues. These swine were infertile, had insulin resistance, and demonstrated an accelerated form of osteochondritis dissicans. Our results show that excess pGH produces a phenotype identical to that seen in swine expressing heterologous growth hormones, and provides a baseline for assessing the overall efficiency of producing transgenic swine. Furthermore, our data suggests that unregulated pGH production, even at 15 times normal levels and independent of the tissue source, has adverse effects that outweigh the desired reduction in carcass fat deposition in transgenic swine. 相似文献
28.
Carlos Rafael Borges Mendes Raul Rodrigo Costa Afonso Ferreira Bruno Jesus Virginia Maria Tavano Tiago Segabinazzi Dotto Miguel Costa Leal Rodrigo Kerr Carolina Antuarte Islabão Andréa de Oliveira da Rocha Franco Mauricio M. Mata Carlos Alberto Eiras Garcia Eduardo Resende Secchi 《Global Change Biology》2023,29(7):1791-1808
The western Antarctic Peninsula (WAP) is a climatically sensitive region where foundational changes at the basis of the food web have been recorded; cryptophytes are gradually outgrowing diatoms together with a decreased size spectrum of the phytoplankton community. Based on a 11-year (2008–2018) in-situ dataset, we demonstrate a strong coupling between biomass accumulation of cryptophytes, summer upper ocean stability, and the mixed layer depth. Our results shed light on the environmental conditions favoring the cryptophyte success in coastal regions of the WAP, especially during situations of shallower mixed layers associated with lower diatom biomass, which evidences a clear competition or niche segregation between diatoms and cryptophytes. We also unravel the cryptophyte photo-physiological niche by exploring its capacity to thrive under high light stress normally found in confined stratified upper layers. Such conditions are becoming more frequent in the Antarctic coastal waters and will likely have significant future implications at various levels of the marine food web. The competitive advantage of cryptophytes in environments with significant light level fluctuations was supported by laboratory experiments that revealed a high flexibility of cryptophytes to grow in different light conditions driven by a fast photo-regulating response. All tested physiological parameters support the hypothesis that cryptophytes are highly flexible regarding their growing light conditions and extremely efficient in rapidly photo-regulating changes to environmental light levels. This plasticity would give them a competitive advantage in exploiting an ecological niche where light levels fluctuate quickly. These findings provide new insights on niche separation between diatoms and cryptophytes, which is vital for a thorough understanding of the WAP marine ecosystem. 相似文献
29.
Markus Ernstberger Pascal Boeswetter Tobias Baselt Frank Ebert Fabiola Basan Hanno Steinke Niels Hammer Ronny Grunert Peter Hartmann 《Journal of biophotonics》2013,6(4):310-313
Thin slices of human tissues are characterized concerning reflection and transmission in a wavelength range from 400 to 1700 nm. The results are primarily useful to find a wavelength for the detection of subjacent blood vessels during surgical procedures, especially neurological surgery. The measurements have been conducted using a customized measuring station, utilizing two halogen bulb lamps and two spectrometers. This paper focuses on creating a data base with the optical properties of artery, brain, bone, nasal mucosa, and nerve. The spectral distributions are compared among each other, similarities and differences are pointed out. Each tissue has got unique spectral characteristics, whereas typical absorption bands can be found in the overall tissues, especially hemoglobin and water absorption bands. The reflectivity maxima are typically located in the red or near‐infrared. All the transmission maxima are located between 1075 nm and 1100 nm. The measurements have been conducted at the Institute of Anatomy at the University of Leipzig. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
30.