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991.
Hadia Elhadi Slama Amor Romdhane Leila Cheikh M’Hamed Hatem Fahej Mohamed Ali Saed Radhouane Leila 《Journal of Plant Growth Regulation》2023,42(1):304-318
Journal of Plant Growth Regulation - Salt stress is a main factor limiting the production and productivity of wheat in arid and semi-arid zones. The objectives of this study were to compare the... 相似文献
992.
Shaida Mahmoudi Mohamad Javad Chaichi Mojtaba Shamsipur Ome Leila Nazari Abdolraouf Samadi-Maybodi 《Luminescence》2023,38(10):1711-1719
Atropine (AT) is an anticholinergic drug. AT is abundantly in Datura plant seeds. Fe3O4@Zn/Mg MOF (Fe3O4@MOF) composite was synthesized. The compound had a high peroxidase-like activity in a chemiluminescence (CL) reaction. Addition of AT quenched CL. The linear range and limit of detection were 5–600 μg L−1 and 2 × 10−2 μg L−1. This method is fast, reversible, and selective, without biodegradability effects, high accuracy, and precision for measuring AT in the Datura plant. 相似文献
993.
In the Atlantic Montane Rain Forest of south-eastern Brazil, a field study was carried out to describe the forest disturbance
regime, analyse canopy gap composition and evaluate the influence of habitat parameters on gap tree species composition. We
characterized canopy gaps considering the group of variables as follows: area, type and number of tree/branch falls, topographic
position, soil coverage and surrounding canopy trees. Gap composition was assessed at species level by measuring all individuals
inside gaps higher than one meter. Mean gap area of the 42 canopy gaps analysed was 71.9 ± 9.0 m2 (mean ± SE). Out of the
studied gaps, 35.7% were created by uprooted and by snapped trees, 16.7% by dead-standing trees and 11.9% by the fall of large
branches. The disturbance regime was characterized by gap openings predominantly smaller than 150 m2 and by spatial patterning
related to topography. Ridges had smaller gaps and higher proportions of gaps created by branch falls; slopes had bigger gaps
generally created by uprooting events. The more abundant and frequent species were shade tolerant and the more species-rich
families found inside gaps did not differ from the forest as a whole. Pioneer species were rare and restricted to medium and
large size classes. The Indicator Species Analysis and the Canonical Correspondence Analysis indicated gap area, topography
and the percentage of soil cover by the genera Calathea and Ctenanthe were the predominant variables correlated with woody species distribution. So, topography emerged as an important issue not
only to the gap disturbance regime, but also to gap colonization. In respect to the influence of gap processes on the Atlantic
Montane Rain Forest regeneration, our results support the view that canopy gap events may not be working as promoters of community
wide floristic shifts. 相似文献
994.
Mapping the structural core of human cerebral cortex 总被引:2,自引:0,他引:2
Structurally segregated and functionally specialized regions of the human cerebral cortex are interconnected by a dense network of cortico-cortical axonal pathways. By using diffusion spectrum imaging, we noninvasively mapped these pathways within and across cortical hemispheres in individual human participants. An analysis of the resulting large-scale structural brain networks reveals a structural core within posterior medial and parietal cerebral cortex, as well as several distinct temporal and frontal modules. Brain regions within the structural core share high degree, strength, and betweenness centrality, and they constitute connector hubs that link all major structural modules. The structural core contains brain regions that form the posterior components of the human default network. Looking both within and outside of core regions, we observed a substantial correspondence between structural connectivity and resting-state functional connectivity measured in the same participants. The spatial and topological centrality of the core within cortex suggests an important role in functional integration. 相似文献
995.
Bicudo TC Bicudo RC Forato LA Beltramini LM Batista LA Filho RB Colnago LA 《Biopolymers》2008,89(3):175-178
The proline-rich N-terminal domain of gamma-zein has been reported in relevant processes, which include its ability to cross the cell membranes. Evidences indicate that synthetic hexapeptide (PPPVHL), naturally found in N-terminal portion of gamma-zein, can adopt the polyproline II (PPII) conformation in aqueous solution. The secondary structure of gamma-zein in maize protein bodies had been analyzed by solid state Fourier transform infrared and nuclear magnetic resonance spectroscopies. However, it was not possible to measure PPII content in physiological environment since the beta-sheet and PPII signals overlap in both solid state techniques. Here, the secondary structure of gamma-zein has been analyzed by circular dichroism in SDS aqueous solution with and without ditiothreitol (DTT), and in 60% of 2-propanol and water with DTT. The results show that gamma-zein has high helical content in all solutions. The PPII conformation was present at about 7% only in water/DTT solution. 相似文献
996.
Xavier Gigandet Patric Hagmann Maciej Kurant Leila Cammoun Reto Meuli Jean-Philippe Thiran 《PloS one》2008,3(12)
Background
Since the emergence of diffusion tensor imaging, a lot of work has been done to better understand the properties of diffusion MRI tractography. However, the validation of the reconstructed fiber connections remains problematic in many respects. For example, it is difficult to assess whether a connection is the result of the diffusion coherence contrast itself or the simple result of other uncontrolled parameters like for example: noise, brain geometry and algorithmic characteristics.Methodology/Principal Findings
In this work, we propose a method to estimate the respective contributions of diffusion coherence versus other effects to a tractography result by comparing data sets with and without diffusion coherence contrast. We use this methodology to assign a confidence level to every gray matter to gray matter connection and add this new information directly in the connectivity matrix.Conclusions/Significance
Our results demonstrate that whereas we can have a strong confidence in mid- and long-range connections obtained by a tractography experiment, it is difficult to distinguish between short connections traced due to diffusion coherence contrast from those produced by chance due to the other uncontrolled factors of the tractography methodology. 相似文献997.
Radhouane L 《Comptes rendus biologies》2008,331(3):206-214
The variations in the hydrous characteristics - leaf water potential (psi(F)) and relative water content (TRE) - of plants indicate their hydrous status and also their capacity to incorporate water, particularly in situations of hydrous stress. These characteristics were used to differentiate the behaviour of six autochthonous ecotypes of pearl millet (Pennisetum glaucum (L.) R. Br.) subjected to various hydrous modes. The results showed that the psi(F) and the TRE evolve in the same direction and decrease in the presence of hydrous stress. These hydrous characteristics are also very important, since they condition the yield. The study also showed that the six pear millet ecotypes present two standard behaviours: the first type is characterized by an important fall of the psi(F) and TRE, representing an osmotic adjustment of adaptive type, whereas the second group showed a weak reduction of leaf water potential while maintaining a TRE appreciably higher, which could be the result of an important reduction of the osmotic potential due to an active accumulation of solutes (constitutive osmotic adjustment). Moreover, the genetic variability of ecotypes with respect to the hydrous stress does not seem related to the geographical origin of the millet ecotypes, but rather to their phenology and their morphology. 相似文献
998.
Elina Lahti Olli Ruoho Leila Rantala Marja-Liisa Hnninen Tuula Honkanen-Buzalski 《Applied microbiology》2003,69(1):554-561
In a longitudinal study in a Finnish cattle finishing unit we investigated excretion and sources of Escherichia coli O157 in bulls from postweaning until slaughter. Three groups of 31 to 42 calves were sampled in a calf transporter before they entered the farm and four to seven times at approximately monthly intervals at the farm. All calves sampled in the livestock transporter were negative for E. coli O157 on arrival, whereas positive animals were detected 1 day later. During the fattening period the E. coli O157 infection rate varied between 0 and 38.5%. The animals were also found to be shedding during the cold months. E. coli O157 was isolated from samples taken from water cups, floors, and feed passages. E. coli O157 was detected in 9.7 to 38.9% of the fecal samples taken at slaughter, while only two rumen samples and one carcass surface sample were found to be positive. E. coli O157 was isolated from barn surface samples more often when the enrichment time was 6 h than when the enrichment time was 24 h (P < 0.0001). Fecal samples taken at the abattoir had lower counts (≤0.4 MPN/g) than fecal samples at the farm (P < 0.05). E. coli O157 was isolated more often from 10-g fecal samples than from 1-g fecal samples (P < 0.0001). Most farm isolates belonged to one pulsed-field gel electrophoresis (PFGE) genotype (79.6%), and the rest belonged to closely related PFGE genotypes. In conclusion, this study indicated that the finishing unit rather than introduction of new cattle was the source of E. coli O157 at the farm and that E. coli O157 seemed to persist well on barn surfaces. 相似文献
999.
1000.
Circadian rhythms, that are governed physiologically and behaviorally by endogenous clock, have been described in many species. Living organisms use this endogenous circadian clock to anticipate environmental transitions, perform activities at biologically advantageous times during the day, and undergo characteristic seasonal responses. Gene duplication is one of the most important mechanisms in the evolution of gene diversity. After duplication, one or both of duplicates can accumulate amino acid changes, thereby promoting functional divergence through the action of natural selection. The circadian system, like many other multigene families, has undergone this genetic revolution, and so circadian genes that are found in single copies in insects are duplicated in vertebrates. We analyzed six groups of genes involved in vertebrates' circadian rhythm pathway to find signatures of molecular evolutionary processes such as gene duplication, natural selection, recombination, and functional divergence. The obtained results, then, were used to determine what evolutionary forces have influenced the fates of duplicated genes of each group. We showed in this research that recombination has not been widespread during the evolution of circadian genes and that purifying selection has been the prominent natural pressure operating on circadian genes. We also showed that the evolution of circadian genes has been depended on gene duplication and functional divergence. Finally, we put forward models best describing the evolutionary fates of circadian duplicates. 相似文献