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41.
Bacteriophage crosses using density-labeled parents have been carried out under conditions restricting DNA synthesis. The parental material and genetic contributions to progeny manifesting recombination within a genetic interval sufficiently short to exhibit high negative interference have been examined. The unreplicated products of recombination isolated as phage particles appear to contain long continuous heteroduplex regions which are heterozygous for the closely linked markers. Recombination between closely linked markers seems to be the consequence of the removal of base-pair mismatches that are present within the heteroduplex regions. This localized reduction of heterozygosity within the heteroduplex regions that join the parental components of recombinant DNA molecules can account for high negative interference. 相似文献
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The disappearance of ‘dissolved’ organic carbon (D. O. C.) leached from maple, aspen, cedar and pine leaves was followed in hard and soft stream water and hard and soft stream water plus sediment. Differences were found in the rates and extent of the disappearance of D. O. C. between the leaves and the water types. These are discussed in relation to the productivity of two extreme stream types. 相似文献
44.
Alain Dejean Arthur Compin Maurice Leponce Frédéric Azémar Camille Bonhomme Stanislas Talaga Laurent Pelozuelo Yann Hénaut Bruno Corbara 《Comptes rendus biologies》2018,341(3):200-207
In an inundated Mexican forest, 89 out of 92 myrmecophytic tank bromeliads (Aechmea bracteata) housed an associated ant colony: 13 sheltered Azteca serica, 43 Dolichoderus bispinosus, and 33 Neoponera villosa. Ant presence has a positive impact on the diversity of the aquatic macroinvertebrate communities (n = 30 bromeliads studied). A Principal Component Analysis (PCA) showed that the presence and the species of ant are not correlated to bromeliad size, quantity of water, number of wells, filtered organic matter or incident radiation. The PCA and a generalized linear model showed that the presence of Azteca serica differed from the presence of the other two ant species or no ants in its effects on the aquatic invertebrate community (more predators). Therefore, both ant presence and species of ant affect the composition of the aquatic macroinvertebrate communities in the tanks of A. bracteata, likely due to ant deposition of feces and other waste in these tanks. 相似文献
45.
Maurice Jay Bernard Voirin Aurangzeb Hasan Jean-François Gonnet Marie-Rose Viricel 《Biochemical Systematics and Ecology》1980,8(2):127-132
A survey of the leaves and flowers of 62 representatives of the tribe Loteae (Leguminosae) showed the presence of several classes of flavonoids: flavonol 7-methyl ethers (rhamnocitrin, rhamnetin), 8-O-substituted flavonols (gossypetin, limocitrin, sexangularetin, corniculatusin), 3′,4′,5′-tri-O-substituted flavonols (myricetin, mearnsetin, syringetin, laricitrin), proanthocyanidins and flavone-C-glycosides. The trisubstitution of the B-ring and the 8-O-substitution of the A-ring allow the definition of a major group including the genera Dorycnium, Bonjeania, Lotus and Tetragonolobus. The presence of proanthocyanidins and 7-O-methylation determine a second group consisting of the genus Anthyllis. Finally, Securigera, on the basis of its flavonoid chemistry, appears to be rather remote from other members of the tribe. 相似文献
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47.
On the Mechanism of Integration of Transforming Deoxyribonucleate 总被引:12,自引:0,他引:12
Maurice S. Fox 《The Journal of general physiology》1966,49(6):183-196
The characteristics of the intermediates in the reaction, between DNA and pneumococcus, that results in genetic transformation are described in so far as they have been characterized. Transformation with DNA isolated from bacteria carrying in addition to genetic markers 32P as a radioactive label and 2H and 15N as density labels has permitted the characterization of the product of recombination between the newly introduced DNA and the DNA of a recipient bacterium. The evidence for a single strand displacement mechanism producing a hybrid structure in the DNA of the recipient bacteria is presented. Progeny of single transformants have been examined. The results of these segregation studies permit the further characterization of this hybrid product of transformation as a genetically heterozygous structure. 相似文献
48.
Lin Chung-Ying Cheng Andy S. K. Imani Vida Saffari Mohsen Ohayon Maurice M. Pakpour Amir H. 《Sleep and biological rhythms》2020,18(4):343-349
Sleep and Biological Rhythms - To examine the psychometric properties of the Sleep Condition Indicator (SCI) using different psychometric approaches [including classical test theory, Rasch models,... 相似文献
49.
Felde Vivian A. Flantua Suzette G. A. Jenks Cathy R. Benito Blas M. de Beaulieu Jacques-Louis Kuneš Petr Magri Donatella Nalepka Dorota Risebrobakken Bjørg ter Braak Cajo J. F. Allen Judy R. M. Granoszewski Wojciech Helmens Karin F. Huntley Brian Kondratienė Ona Kalniņa Laimdota Kupryjanowicz Mirosława Malkiewicz Małgorzata Milner Alice M. Nita Małgorzata Noryśkiewicz Bożena Pidek Irena A. Reille Maurice Salonen J. Sakari Šeirienė Vaida Winter Hanna Tzedakis Polychronis C. Birks H. John B. 《Vegetation History and Archaeobotany》2020,29(1):101-109
Vegetation History and Archaeobotany - The Eemian interglacial represents a natural experiment on how past vegetation with negligible human impact responded to amplified temperature changes... 相似文献
50.
Agathe Hess Lianchun Yu Isabelle Klein Marine De Mazancourt Gilles Jebrak Hervé Mal Olivier Brugière Michel Fournier Maurice Courbage Gaelle Dauriat Elisabeth Schouman-Clayes Christine Clerici Laurence Mangin 《PloS one》2013,8(10)
Breathing is maintained and controlled by a network of automatic neurons in the brainstem that generate respiratory rhythm and receive regulatory inputs. Breathing complexity therefore arises from respiratory central pattern generators modulated by peripheral and supra-spinal inputs. Very little is known on the brainstem neural substrates underlying breathing complexity in humans. We used both experimental and theoretical approaches to decipher these mechanisms in healthy humans and patients with chronic obstructive pulmonary disease (COPD). COPD is the most frequent chronic lung disease in the general population mainly due to tobacco smoke. In patients, airflow obstruction associated with hyperinflation and respiratory muscles weakness are key factors contributing to load-capacity imbalance and hence increased respiratory drive. Unexpectedly, we found that the patients breathed with a higher level of complexity during inspiration and expiration than controls. Using functional magnetic resonance imaging (fMRI), we scanned the brain of the participants to analyze the activity of two small regions involved in respiratory rhythmogenesis, the rostral ventro-lateral (VL) medulla (pre-Bötzinger complex) and the caudal VL pons (parafacial group). fMRI revealed in controls higher activity of the VL medulla suggesting active inspiration, while in patients higher activity of the VL pons suggesting active expiration. COPD patients reactivate the parafacial to sustain ventilation. These findings may be involved in the onset of respiratory failure when the neural network becomes overwhelmed by respiratory overload We show that central neural activity correlates with airflow complexity in healthy subjects and COPD patients, at rest and during inspiratory loading. We finally used a theoretical approach of respiratory rhythmogenesis that reproduces the kernel activity of neurons involved in the automatic breathing. The model reveals how a chaotic activity in neurons can contribute to chaos in airflow and reproduces key experimental fMRI findings. 相似文献