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11.
Bernard Junod Adrian Griffiths Roland Lüthi Hannes B. St?helin Heikki Savolainen et al. 《International journal of biometeorology》1992,36(3):179-189
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Our Planet, Our Health Report of the who commission on health and environment 相似文献12.
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Transient expression of foreign genes introduced on a plasmid into isolated plant protoplasts is widely used to study the control of gene expression. Unfortunately, many experimental variables implicated in this technique are difficult or impossible to control, resulting in a disturbing degree of variability between otherwise identical experiments. We have studied the co-expression of two constitutively expressed genes located on the same plasmid. This has allowed us to identify the lot of plasmid DNA as an important source of variation, along with the protoplast lot. Plasmid DNA concentration was found to be of minor importance. Since the variation of expression level of the two genes was identical for the two genes in all experiments, we propose the use of an internal standard in all comparative transient expression studies, which allows the reduction of the variation between experiments by one order of magnitude.Abbreviations CaMV
cauliflower mosaic virus
- CAT
chloramphenicol acetyl transferase
- GUS
ß-glucuronidase synthase
- MS
medium after Murashige and Skoog (1962)
- MU
methyl umbelliferone
- NOS
nopaline synthase
- NPT
II-neomycin phospho transferase
- PEG
polyethylene glycol
- Tris
tris-hydroxymethyl aminoethane 相似文献
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Hannes Hentze Poh Loong Soong Siew Tein Wang Blaine W. Phillips Thomas C. Putti N. Ray Dunn 《Stem cell research》2009,2(3):198-210
Transplantation of human embryonic stem cells (hESC) into immune-deficient mice leads to the formation of differentiated tumors comprising all three germ layers, resembling spontaneous human teratomas. Teratoma assays are considered the gold standard for demonstrating differentiation potential of pluripotent hESC and hold promise as a standard for assessing safety among hESC-derived cell populations intended for therapeutic applications. We tested the potency of teratoma formation in seven anatomical transplantation locations (kidney capsule, muscle, subcutaneous space, peritoneal cavity, testis, liver, epididymal fat pad) in SCID mice with and without addition of Matrigel, and found that intramuscular teratoma formation was the most experimentally convenient, reproducible, and quantifiable. In the same experimental setting, we compared undifferentiated hESC and differentiated populations enriched for either beating cardiomyocytes or definitive endoderm derivatives (insulin-secreting beta cells), and showed that all cell preparations rapidly formed teratomas with varying percentages of mesoderm, ectoderm, and endoderm. In limiting dilution experiments, we found that as little as two hESC colonies spiked into feeder fibroblasts produced a teratoma, while a more rigorous single-cell titration achieved a detection limit of 1/4000. In summary, we established core parameters essential for facilitating safety profiling of hESC-derived products for future therapeutic applications. 相似文献
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Marijn Bauters Sofie Meeus Matti Barthel Piet Stoffelen Hannes P. T. De Deurwaerder Flicien Meunier Travis W. Drake Quentin Ponette Jerme Ebuy Pieter Vermeir Hans Beeckman Francis wyffels Samuel Bod Hans Verbeeck Filip Vandelook Pascal Boeckx 《Global Change Biology》2020,26(8):4449-4461
Forests exhibit leaf‐ and ecosystem‐level responses to environmental changes. Specifically, rising carbon dioxide (CO2) levels over the past century are expected to have increased the intrinsic water‐use efficiency (iWUE) of tropical trees while the ecosystem is gradually pushed into progressive nutrient limitation. Due to the long‐term character of these changes, however, observational datasets to validate both paradigms are limited in space and time. In this study, we used a unique herbarium record to go back nearly a century and show that despite the rise in CO2 concentrations, iWUE has decreased in central African tropical trees in the Congo Basin. Although we find evidence that points to leaf‐level adaptation to increasing CO2—that is, increasing photosynthesis‐related nutrients and decreasing maximum stomatal conductance, a decrease in leaf δ13C clearly indicates a decreasing iWUE over time. Additionally, the stoichiometric carbon to nitrogen and nitrogen to phosphorus ratios in the leaves show no sign of progressive nutrient limitation as they have remained constant since 1938, which suggests that nutrients have not increasingly limited productivity in this biome. Altogether, the data suggest that other environmental factors, such as increasing temperature, might have negatively affected net photosynthesis and consequently downregulated the iWUE. Results from this study reveal that the second largest tropical forest on Earth has responded differently to recent environmental changes than expected, highlighting the need for further on‐ground monitoring in the Congo Basin. 相似文献
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Plant and Soil - The ecological study of root systems lags behind the understanding of the aboveground components of plant communities, mainly due to methodological challenges. As ecological root... 相似文献
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David Pretzel Stefanie Linss Hannes Ahrem Michaela Endres Christian Kaps Dieter Klemm Raimund W Kinne 《Arthritis research & therapy》2013,15(3):R59