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91.
Michael J. Remke Tonny Hoang Thomas Kolb Catherine Gehring Nancy C. Johnson Matthew A. Bowker 《Restoration Ecology》2020,28(Z4):S344-S354
Changes in temperature and moisture as a result of climate forcing can impact performance of planted trees. Tree performance may also be sensitive to new soil conditions, for example, brought about by seeds germinating in soils different from those colonized by ancestral populations. Such “edaphic constraint” may occur with natural migration or human‐assisted movement. Pinus ponderosa seedlings, sourced from one location (“home” site), were grown across a field environmental gradient in either their original home soil or in soils from two different “away” sites. Seedlings were inoculated with site‐specific soil organisms by germinating seeds in living soil. After 6 months, the inoculated seedlings were transplanted into sterilized soils from the home or away sites. This experimental design allowed us to uncouple the importance of abiotic and biotic soil properties and test (1) how biotic and abiotic soil properties interact with climate to influence plant growth and stress tolerance, and (2) the role of soil biota in facilitating growth in novel environments. Seedlings grew least in hotter and drier away sites with away soil biota. Home soil biota ameliorated negative impacts on growth of hotter and drier away sites. Measurements of photosynthetic rate, stomatal conductance, and chlorophyll florescence (Fv/Fm) suggest that edaphic constraint reduced growth by increasing tree water stress. Results suggest that success of Ponderosa pine plantings into warming environments will be enhanced by pre‐inoculation with native soil biota of the seed source. 相似文献
92.
Deprenyl Protects Dopamine Neurons from the Neurotoxic Effect of 1-Methyl-4-Phenylpyridinium Ion 总被引:1,自引:2,他引:1
1-Methyl-4-phenylpyridinium ion (MPP+) is the product of the metabolic oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by monoamine oxidase (MAO). MPP+ is toxic to 3,4-dihydroxyphenylethylamine (dopamine, DA) neurons in explant cultures of rat embryonic midbrain. Addition of 2.5 microM MPP+ to the feeding medium for 6 days results in significant reduction of the DA levels in the cultures (to 19% of control) as well as in the uptake of [3H]DA (to 32% of control). When the cultures are treated with the MAO inhibitor deprenyl (10 microM) 24 h prior to and during exposure to MPP+, the DA neurons are protected from the toxicity of the drug. In the combined deprenyl plus MPP+ treatment, the levels of DA in the cultures remain at the control range and the [3H]DA uptake is reduced to only 73% of control. These results indicate that MAO is involved in the toxicity of MPP+ on DA neurons. 相似文献
93.
94.
Evgeni V. Sokurenko Veronika Tchesnokova Anthony T. Yeung Catherine A. Oleykowski Elena Trintchina Kelly T. Hughes Rebecca A. Rashid J. Mark Brint Steve L. Moseley Stephen Lory 《Nucleic acids research》2001,29(22):e111
We have developed a novel technology that makes it possible to detect simple nucleotide polymorphisms directly within a sample of total genomic DNA. It allows, in a single Southern blot experiment, the determination of sequence identity of genomic regions with a combined length of hundreds of kilobases. This technology does not require PCR amplification of the target DNA regions, but exploits preparative size-fractionation of restriction-digested genomic DNA and a newly discovered property of the mismatch-specific endonuclease CEL I to cleave heteroduplex DNA with a very high specificity and sensitivity. We have used this technique to detect various simple mutations directly in the genomic DNA of isogenic pairs of recombinant Pseudomonas aeruginosa, Escherichia coli and Salmonella isolates. Also, by using a cosmid DNA library and genomic fractions as hybridization probes, we have compared total genomic DNA of two clinical P.aeruginosa clones isolated from the same patient, but exhibiting divergent phenotypes. The mutation scan correctly detected a GA insertion in the quorum-sensing regulator gene rhlR and, in addition, identified a novel intragenomic polymorphism in rrn operons, indicating very high stability of the bacterial genomes under natural non-mutator conditions. 相似文献
95.
Caymen M. Novak Eric N. Horst Charles C. Taylor Catherine Z. Liu Geeta Mehta 《Biotechnology and bioengineering》2019,116(11):3084-3097
Breast cancer cells experience a range of shear stresses in the tumor microenvironment (TME). However most current in vitro three-dimensional (3D) models fail to systematically probe the effects of this biophysical stimuli on cancer cell metastasis, proliferation, and chemoresistance. To investigate the roles of shear stress within the mammary and lung pleural effusion TME, a bioreactor capable of applying shear stress to cells within a 3D extracellular matrix was designed and characterized. Breast cancer cells were encapsulated within an interpenetrating network hydrogel and subjected to shear stress of 5.4 dynes cm−2 for 72 hr. Finite element modeling assessed shear stress profiles within the bioreactor. Cells exposed to shear stress had significantly higher cellular area and significantly lower circularity, indicating a motile phenotype. Stimulated cells were more proliferative than static controls and showed higher rates of chemoresistance to the anti-neoplastic drug paclitaxel. Fluid shear stress-induced significant upregulation of the PLAU gene and elevated urokinase activity was confirmed through zymography and activity assay. Overall, these results indicate that pulsatile shear stress promotes breast cancer cell proliferation, invasive potential, chemoresistance, and PLAU signaling. 相似文献
96.
Merav Gleit Kielmanowicz Alex Inberg Inbar Maayan Lerner Yael Golani Nicholas Brown Catherine Louise Turner Gerald J. R. Hayes Joan M. Ballam 《PLoS pathogens》2015,11(4)
Over the last decade, unusually high losses of colonies have been reported by beekeepers across the USA. Multiple factors such as Varroa destructor, bee viruses, Nosema ceranae, weather, beekeeping practices, nutrition, and pesticides have been shown to contribute to colony losses. Here we describe a large-scale controlled trial, in which different bee pathogens, bee population, and weather conditions across winter were monitored at three locations across the USA. In order to minimize influence of various known contributing factors and their interaction, the hives in the study were not treated with antibiotics or miticides. Additionally, the hives were kept at one location and were not exposed to potential stress factors associated with migration. Our results show that a linear association between load of viruses (DWV or IAPV) in Varroa and bees is present at high Varroa infestation levels (>3 mites per 100 bees). The collection of comprehensive data allowed us to draw a predictive model of colony losses and to show that Varroa destructor, along with bee viruses, mainly DWV replication, contributes to approximately 70% of colony losses. This correlation further supports the claim that insufficient control of the virus-vectoring Varroa mite would result in increased hive loss. The predictive model also indicates that a single factor may not be sufficient to trigger colony losses, whereas a combination of stressors appears to impact hive health. 相似文献
97.
98.
Relative Ability of Orally Administered Lactobacillus murinus To Predominate and Persist in the Porcine Gastrointestinal Tract 总被引:1,自引:0,他引:1 下载免费PDF全文
Gillian E. Gardiner Pat G. Casey Garrett Casey P. Brendan Lynch Peadar G. Lawlor Colin Hill Gerald F. Fitzgerald Catherine Stanton R. Paul Ross 《Applied microbiology》2004,70(4):1895-1906
Five porcine-derived Lactobacillus or Pediococcus isolates administered to pigs (n = 4), either singly or as a combination at ~1010 CFU per day varied with respect to intestinal survival and persistence. Two Lactobacillus murinus strains survived best and were excreted at ~107 to 108 CFU/g of feces. In contrast, Pediococcus pentosaceus DPC6006 had the lowest fecal count at ~105 CFU/g and was excreted at a significantly lower level than both L. murinus strains. Fecal L. murinus DPC6003 counts were also significantly higher than both Lactobacillus salivarius DPC6005 and Lactobacillus pentosus DPC6004 (~106 CFU/g). The L. murinus strains persisted for at least 9 days postadministration in both the feces and the cecum. Animals fed a combination of all five strains excreted ~107 CFU of the administered strains/g, with L. murinus predominating, as determined by randomly amplified polymorphic DNA PCR. Postadministration, variation was observed between animals fed the strain combination, but in general, L. murinus DPC6002 and DPC6003 and L. pentosus DPC6004 predominated in the feces and the cecum while P. pentosaceus DPC6006 was detected only in the cecum. Fifteen days after the start of culture administration, mean fecal Enterobacteriaceae counts were significantly lower in some of the treatment groups. In addition, when mean preadministration counts were compared with those obtained after 21 days of culture administration, Enterobacteriaceae counts were reduced by ~87 to 98% in pigs fed L. salivarius DPC6005, P. pentosaceus DPC6006, L. pentosus DPC6004, and the culture mix. In conclusion, the porcine intestinal isolates have potential as probiotic feed additives for pigs, with differences in strain performance highlighting the advantages of using culture combinations. 相似文献
99.
An Arabidopsis expressed sequence tag clone, 221D24, encoding a lipase has been characterized using an antisense approach. The lipase gene is expressed during normal growth and development of Arabidopsis rosette leaves but is down-regulated as the leaves senesce. When plants are exposed to sublethal levels of UV-B radiation, expression of the lipase is strongly up-regulated. The lipase protein is localized in the cell cytosol and is present in all organs of Arabidopsis plants. Recombinant lipase protein produced in Escherichia coli preferentially hydrolyzed phospholipids, indicating that the gene encodes a phospholipase. Transgenic plants in which lipase expression is suppressed showed enhanced tolerance to UV-B stress but not osmotic stress and were unable to up-regulate PR-1 expression when irradiated with UV-B. The observations collectively indicate that the lipase is capable of deesterifying membrane phospholipids and is up-regulated in response to UV-B irradiation. 相似文献
100.
D Rainteau L Humbert E Delage C Vergnolle C Cantrel MA Maubert S Lanfranchi R Maldiney S Collin C Wolf A Zachowski E Ruelland 《PloS one》2012,7(7):e41985