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This study describes a broad host transformation protocol that enables the uptake of plasmid DNA into 10 different species of Bifidobacterium , some of which have never been transformed before. The vector pNC7 (4·9 kb) was used to optimize the electroporation protocol. Transformation efficiencies ranged from 3·6×10−1 to 1·2×105 transformations per μg DNA. The impact of growth medium composition and electric field strength on transformation efficiency were independently optimized. Electrocompetent cells were grown in Iwata medium broth enriched with ActilightR P 16%, harvested during the early exponential growth phase, and pulsed at 12·5 kV cm−1 , 100 Ω and 25 μF. 相似文献
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G Polese A Rossi L Appendini G Brandi J H Bates R Brandolese 《Journal of applied physiology》1991,71(6):2425-2433
In ten mechanically ventilated patients, six with chronic obstructive pulmonary disease (COPD) and four with pulmonary edema, we have partitioned the total respiratory system mechanics into the lung (l) and chest wall (w) mechanics using the esophageal balloon technique together with the airway occlusion technique during constant-flow inflation (J. Appl. Physiol. 58: 1840-1848, 1985). Intrinsic positive end-expiratory pressure (PEEPi) was present in eight patients (range 1.1-9.8 cmH2O) and was due mainly to PEEPi,L (80%), with a minor contribution from PEEPi,w (20%), on the average. The increase in respiratory elastance and resistance was determined mainly by abnormalities in lung elastance and resistance. Chest wall elastance was slightly abnormal (7.3 +/- 2.2 cmH2O/l), and chest wall resistance contributed only 10%, on the average, to the total. The work performed by the ventilator to inflate the lung (WL) averaged 2.04 +/- 0.59 and 1.25 +/- 0.21 J/l in COPD and pulmonary edema patients, respectively, whereas Ww was approximately 0.4 J/l in both groups, i.e., close to normal values. We conclude that, in mechanically ventilated patients, abnormalities in total respiratory system mechanics essentially reflect alterations in lung mechanics. However, abnormalities in chest wall mechanics can be relevant in some COPD patients with a high degree of pulmonary hyperinflation. 相似文献
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Duccio Malinverni Simone Marsili Alessandro Barducci Paolo De Los Rios 《PLoS computational biology》2015,11(6)
Hsp70s are a class of ubiquitous and highly conserved molecular chaperones playing a central role in the regulation of proteostasis in the cell. Hsp70s assist a myriad of cellular processes by binding unfolded or misfolded substrates during a complex biochemical cycle involving large-scale structural rearrangements. Here we show that an analysis of coevolution at the residue level fully captures the characteristic large-scale conformational transitions of this protein family, and predicts an evolutionary conserved–and thus functional–homo-dimeric arrangement. Furthermore, we highlight that the features encoding the Hsp70 dimer are more conserved in bacterial than in eukaryotic sequences, suggesting that the known Hsp70/Hsp110 hetero-dimer is a eukaryotic specialization built on a pre-existing template. 相似文献
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Mario Stampanoni Bassi Tommaso Nuzzo Luana Gilio Mattia Miroballo Alessia Casamassa Fabio Buttari Paolo Bellantonio Roberta Fantozzi Giovanni Galifi Roberto Furlan Annamaria Finardi Arianna De Rosa Anna Di Maio Francesco Errico Diego Centonze Alessandro Usiello 《Journal of neurochemistry》2021,159(5):857-866
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Henri Berestycki Jean-Michel Roquejoffre Luca Rossi 《Journal of mathematical biology》2013,66(4-5):743-766
We propose here a new model to describe biological invasions in the plane when a strong diffusion takes place on a line. We establish the main properties of the system, and also derive the asymptotic speed of spreading in the direction of the line. For low diffusion, the line has no effect, whereas, past a threshold, the line enhances global diffusion in the plane and the propagation is directed by diffusion on the line. It is shown here that the global asymptotic speed of spreading in the plane, in the direction of the line, grows as the square root of the diffusion on the line. The model is much relevant to account for the effects of fast diffusion lines such as roads on spreading of invasive species. 相似文献
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Alessandro Minelli 《Molecular phylogenetics and evolution》1998,9(3):340-347
Most traditional views of homology rely on two unwarranted premises: the pervasively hierarchical nature of biology, inclusive of the levels of genes, development, and morphology and the linear mapping of genes onto developmental schedules and of developmental schedules onto phenotypes. These premises are only occasionally verified. Hierarchical behavior is negated by gene duplication and exon shuffling at the level of genes, by the coexistence of autonomous vs nonautonomous gene expression at the level of development, by ontogenetic repatterning at the level of morphology. The linearity of mapping of genes onto development is disturbed by genetic piracy, uncoupling of positional vs spatial control, and pleiotropy. The independence of developmental modules affects the mapping of development onto morphology and, finally, the peculiar topology of the epigenetic code affects the linearity of the gene to phenotype mapping. To cope with this complex behavior, a combinatorial approach to homology is recommended. 相似文献
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