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81.
The objective of this work is to evaluate the ability of some additive substances in protecting the biocontrol agent Candida oleophila (strain O) against the adverse effects of environmental factors, such as water activity (aw, 0.93 and 0.98) and relative humidity (75% and 98%). The protection obtained with various protectant substances, skimmed milk (SM), peptone, maltose, sucrose, sorbitol, lactose and polyethylene glycol was assayed under in vitro and in vivo conditions. The yeast cells with the highest level of protecting agents (1%) had higher viability than those with low protectant levels (0.1% and 0.5%). SM, sucrose and sorbitol improved significantly the C. oleophila survival on apple fruit surface by 80.8%, 42.26% and 37.27% and gave a significant protection (from 96% to 100%) against Penicillium expansum under dried conditions. The highest strain O density and efficacy was obtained with SM. Under experimental conditions reflecting practical conditions, SM applied in combination with the strain O resulted in improved biocontrol efficacy by 74.65%. Therefore, SM could be used as material substrate with the best sugar protectants during the formulation process of this antagonistic yeast for eventual pre-harvest application. 相似文献
82.
Hanene Medini Ameur Elaissi Farhat Farhat Mohamed Larbi Khouja Rachid Chemli Fathia Harzallah‐Skhiri 《化学与生物多样性》2009,6(9):1378-1387
The essential‐oil composition of 60 individual trees of Juniperus phoenicea L. from four Tunisian populations in three different periods were investigated by GC and GC/MS analyses. 59 Compounds were identified in the oils, and a relatively high variation in their contents was found. All the oils were dominated by the terpenic hydrocarbon fraction, and the main component was α‐pinene (20.28–40.86%). The results of the oil compositions were processed by hierarchical clustering and principal component analysis (PCA) allowing establishing four groups of essential‐oils differentiated by one compound or more. Pattern of geographic variation in essential‐oil composition indicated that individuals from the continental site (Makthar) were clearly distinguished from those from littoral localities (Tabarka, Hawaria, and Rimel). 相似文献
83.
In biomechanics, the calculation of individual muscle forces during movements is based on a model of the musculoskeletal system and a method for extracting a unique set of muscle forces. To obtain a unique set of muscle forces, non-linear, static optimisation is commonly used. However, the optimal solution is dependent on the musculoskeletal geometry, and single joints may be represented using one, two or three degrees-of-freedom. Frequently, a system with multiple degrees-of-freedom is replaced with a system that contains a subset of all the possible degrees-of-freedom. For example, the cat ankle joint is typically modelled as a planar joint with its primary degree-of-freedom (plantar-dorsiflexion), whereas, the actual joint has three rotational degrees-of-freedom. Typically, such simplifications are justified by the idea that the reduced case is contained as a specific solution of the more general case. However, here we demonstrate that the force-sharing solution space of a general, three degrees-of-freedom musculoskeletal system does not necessarily contain the solutions from the corresponding one or two degrees-of-freedom systems. Therefore, solutions of a reduced system, in general, are not sub-set solutions of the actual three degrees-of-freedom system, but are independent solutions that are often incompatible with solutions of the actual system. This result shows that representing a three degrees-of-freedom system as a one or two degrees-of-freedom system gives force-sharing solutions that cannot be extrapolated to the actual system, and vice-versa. These results imply that general solutions cannot be extracted from models with fewer degrees-of-freedom than the actual system. They further emphasise the need for precise geometric representation of the musculoskeletal system, if general force-sharing rules are to be derived. 相似文献
84.
Morphological characterization of a novel scaffold for anterior cruciate ligament tissue engineering
Laurent CP Ganghoffer JF Babin J Six JL Wang X Rahouadj R 《Journal of biomechanical engineering》2011,133(6):065001
Tissue engineering offers an interesting alternative to current anterior cruciate ligament (ACL) surgeries. Indeed, a tissue-engineered solution could ideally overcome the long-term complications due to actual ACL reconstruction by being gradually replaced by biological tissue. Key requirements concerning the ideal scaffold for ligament tissue engineering are numerous and concern its mechanical properties, biochemical nature, and morphology. This study is aimed at predicting the morphology of a novel scaffold for ligament tissue engineering, based on multilayer braided biodegradable copoly(lactic acid-co-(e-caprolactone)) (PLCL) fibers The process used to create the scaffold is briefly presented, and the degradations of the material before and after the scaffold processing are compared. The process offers varying parameters, such as the number of layers in the scaffold, the pitch length of the braid, and the fibers' diameter. The prediction of the morphology in terms of pore size distribution and pores interconnectivity as a function of these parameters is performed numerically using an original method based on a virtual scaffold. The virtual scaffold geometry and the prediction of pore size distribution are evaluated by comparison with experimental results. The presented process permits creation of a tailorable scaffold for ligament tissue engineering using basic equipment and from minimum amounts of raw material. The virtual scaffold geometry closely mimics the geometry of real scaffolds, and the prediction of the pore size distribution is found to be in good accordance with measurements on real scaffolds. The scaffold offers an interconnected network of pores the sizes of which are adjustable by playing on the process parameters and are able to match the ideal pore size reported for tissue ingrowth. The adjustability of the presented scaffold could permit its application in both classical ACL reconstructions and anatomical double-bundle reconstructions. The precise knowledge of the scaffold morphology using the virtual scaffold will be useful to interpret the activity of cells once it will be seeded into the scaffold. An interesting perspective of the present work is to perform a similar study aiming at predicting the mechanical response of the scaffold according to the same process parameters, by implanting the virtual scaffold into a finite element algorithm. 相似文献
85.
Champ S Puvirajesinghe TM Perrody E Menouni R Genevaux P Ansaldi M 《The Journal of biological chemistry》2011,286(45):38876-38885
Temperate bacteriophage lytic development is intrinsically related to the stress response in particular at the DNA replication and virion maturation steps. Alternatively, temperate phages become lysogenic and integrate their genome into the host chromosome. Under stressful conditions, the prophage resumes a lytic development program, and the phage DNA is excised before being replicated. The KplE1 defective prophage of Escherichia coli K12 constitutes a model system because it is fully competent for integrative as well as excisive recombination and presents an atypical recombination module, which is conserved in various phage genomes. In this work, we identified the host-encoded stress-responsive molecular chaperone DnaJ (Hsp40) as an active participant in KplE1 prophage excision. We first show that the recombination directionality factor TorI of KplE1 specifically interacts with DnaJ. In addition, we found that DnaJ dramatically enhances both TorI binding to its DNA target and excisive recombination in vitro. Remarkably, such stimulatory effect by DnaJ was performed independently of its DnaK chaperone partner and did not require a functional DnaJ J-domain. Taken together, our results underline a novel and unsuspected functional interaction between the generic host stress-regulated chaperone and temperate bacteriophage lysogenic development. 相似文献
86.
Susan-Resiga D Essalmani R Hamelin J Asselin MC Benjannet S Chamberland A Day R Szumska D Constam D Bhattacharya S Prat A Seidah NG 《The Journal of biological chemistry》2011,286(26):22785-22794
Bone morphogenetic protein 10 (BMP10) is a member of the TGF-β superfamily and plays a critical role in heart development. In the postnatal heart, BMP10 is restricted to the right atrium. The inactive pro-BMP10 (~60 kDa) is processed into active BMP10 (~14 kDa) by an unknown protease. Proteolytic cleavage occurs at the RIRR(316)↓ site (human), suggesting the involvement of proprotein convertase(s) (PCs). In vitro digestion of a 12-mer peptide encompassing the predicted cleavage site with furin, PACE4, PC5/6, and PC7, showed that furin cleaves the best, whereas PC7 is inactive on this peptide. Ex vivo studies in COS-1 cells, a cell line lacking PC5/6, revealed efficient processing of pro-BMP10 by endogenous PCs other than PC5/6. The lack of processing of overexpressed pro-BMP10 in the furin- and PACE4-deficient cell line, CHO-FD11, and in furin-deficient LoVo cells, was restored by stable (CHO-FD11/Fur cells) or transient (LoVo cells) expression of furin. Use of cell-permeable and cell surface inhibitors suggested that endogenous PCs process pro-BMP10 mostly intracellularly, but also at the cell surface. Ex vivo experiments in mouse primary hepatocytes (wild type, PC5/6 knock-out, and furin knock-out) corroborated the above findings that pro-BMP10 is a substrate for endogenous furin. Western blot analyses of heart right atria extracts from wild type and PACE4 knock-out adult mice showed no significant difference in the processing of pro-BMP10, implying no in vivo role of PACE4. Overall, our in vitro, ex vivo, and in vivo data suggest that furin is the major convertase responsible for the generation of BMP10. 相似文献
87.
88.
Rachid Rezgui Roxane Lestini Jo?lle Kühn Xenia Fave Lauren McLeod Hannu Myllykallio Antigoni Alexandrou Cedric Bouzigues 《PloS one》2014,9(11)
As DNA repair enzymes are essential for preserving genome integrity, understanding their substrate interaction dynamics and the regulation of their catalytic mechanisms is crucial. Using single-molecule imaging, we investigated the association and dissociation kinetics of the bipolar endonuclease NucS from Pyrococcus abyssi (Pab) on 5′ and 3′-flap structures under various experimental conditions. We show that association of the PabNucS with ssDNA flaps is largely controlled by diffusion in the NucS-DNA energy landscape and does not require a free 5′ or 3′ extremity. On the other hand, NucS dissociation is independent of the flap length and thus independent of sliding on the single-stranded portion of the flapped DNA substrates. Our kinetic measurements have revealed previously unnoticed asymmetry in dissociation kinetics from these substrates that is markedly modulated by the replication clamp PCNA. We propose that the replication clamp PCNA enhances the cleavage specificity of NucS proteins by accelerating NucS loading at the ssDNA/dsDNA junctions and by minimizing the nuclease interaction time with its DNA substrate. Our data are also consistent with marked reorganization of ssDNA and nuclease domains occurring during NucS catalysis, and indicate that NucS binds its substrate directly at the ssDNA-dsDNA junction and then threads the ssDNA extremity into the catalytic site. The powerful techniques used here for probing the dynamics of DNA-enzyme binding at the single-molecule have provided new insight regarding substrate specificity of NucS nucleases. 相似文献
89.
90.
The invasive brown seaweed Sargassum muticum as new resource for alginate in Morocco: Spectroscopic and rheological characterization 下载免费PDF全文
Samir El Atouani Fouad Bentiss Abdeltif Reani Rachid Zrid Zahira Belattmania Leonel Pereira Abdelhadi Mortadi Omar Cherkaoui Brahim Sabour 《Phycological Research》2016,64(3):185-193
The Japanese brown seaweed Sargassum muticum, recently invaded several shorelines worldwide including the Atlantic coast of Morocco with large well‐established populations. Within the framework of a sustainable strategy to control this invasive seaweed, we report on extraction yield, spectroscopic characterization and rheological properties of alginate, a commercially valuable colloid, from harvested biomass of S. muticum. Extraction yield was about 25.6% on dry weight basis. Infrared spectroscopy analysis shows that the obtained Fourier transform infrared spectra of the extracted biopolymer exhibit strong similarities with that of the commercial alginate. Furthermore, Proton nuclear magnetic resonance spectroscopy revealed that S. muticum alginate has almost equal amounts of β‐D‐mannuronic acid (M; 49%) and α‐L‐guluronic acid (G; 51%) with an M/G ratio of 1.04 and a high content of heteropolymeric MG GM diads suggesting a sequence distribution of an alternated polymer type. Rheological measurements were performed at different sodium alginate concentrations, temperatures and shear rates. The hydrocolloid exhibited pseudoplastic behavior and showed shear thinning, particularly at high solution concentration and low temperature which is consistent with the rheological behavior reported for commercial alginates. Considering the abundance of S. muticum in the Northwestern Atlantic coast of Morocco and the quality of the extracted hydrogel, this invasive species could be considered as a potential source of alginates. 相似文献