59 research outputs found

    Robust inducible Cre recombinase activity in the human malaria parasite Plasmodium falciparum enables efficient gene deletion within a single asexual erythrocytic growth cycle.

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    Asexual blood stages of the malaria parasite, which cause all the pathology associated with malaria, can readily be genetically modified by homologous recombination, enabling the functional study of parasite genes that are not essential in this part of the life cycle. However, no widely applicable method for conditional mutagenesis of essential asexual blood-stage malarial genes is available, hindering their functional analysis. We report the application of the DiCre conditional recombinase system to Plasmodium falciparum, the causative agent of the most dangerous form of malaria. We show that DiCre can be used to obtain rapid, highly regulated site-specific recombination in P. falciparum, capable of excising loxP-flanked sequences from a genomic locus with close to 100% efficiency within the time-span of a single erythrocytic growth cycle. DiCre-mediated deletion of the SERA5 3' UTR failed to reduce expression of the gene due to the existence of alternative cryptic polyadenylation sites within the modified locus. However, we successfully used the system to recycle the most widely used drug resistance marker for P. falciparum, human dihydrofolate reductase, in the process producing constitutively DiCre-expressing P. falciparum clones that have broad utility for the functional analysis of essential asexual blood-stage parasite genes

    Monitoring credit risk in the social economy sector by means of a binary goal programming model

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11628-012-0173-7Monitoring the credit risk of firms in the social economy sector presents a considerable challenge, since it is difficult to calculate ratings with traditional methods such as logit or discriminant analysis, due to the relatively small number of firms in the sector and the low default rate among cooperatives. This paper intro- duces a goal programming model to overcome such constraints and to successfully manage credit risk using economic and financial information, as well as expert advice. After introducing the model, its application to a set of Spanish cooperative societies is described.García García, F.; Guijarro Martínez, F.; Moya Clemente, I. (2013). Monitoring credit risk in the social economy sector by means of a binary goal programming model. 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    RON5 is critical for organization and function of the Toxoplasma moving junction complex

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    Apicomplexans facilitate host cell invasion through formation of a tight-junction interface between parasite and host plasma membranes called the moving junction (MJ). A complex of the rhoptry neck proteins RONs 2/4/5/8 localize to the MJ during invasion where they are believed to provide a stable anchoring point for host penetration. During the initiation of invasion, the preformed MJ RON complex is injected into the host cell where RON2 spans the host plasma membrane while RONs 4/5/8 localize to its cytosolic face. While much attention has been directed toward an AMA1-RON2 interaction supposed to occur outside the cell, little is known about the functions of the MJ RONs positioned inside the host cell. Here we provide a detailed analysis of RON5 to resolve outstanding questions about MJ complex organization, assembly and function during invasion. Using a conditional knockdown approach, we show loss of RON5 results in complete degradation of RON2 and mistargeting of RON4 within the parasite secretory pathway, demonstrating that RON5 plays a key role in organization of the MJ RON complex. While RON8 is unaffected by knockdown of RON5, these parasites are unable to invade new host cells, providing the first genetic demonstration that RON5 plays a critical role in host cell penetration. Although invasion is not required for injection of rhoptry effectors into the host cytosol, parasites lacking RON5 also fail to form evacuoles suggesting an intact MJ complex is a prerequisite for secretion of rhoptry bulb contents. Additionally, while the MJ has been suggested to function in egress, disruption of the MJ complex by RON5 depletion does not impact this process. Finally, functional complementation of our conditional RON5 mutant reveals that while proteolytic separation of RON5 N- and C-terminal fragments is dispensable, a portion of the C-terminal domain is critical for RON2 stability and function in invasion

    Le Mur (dit) d'Hannibal : Un site de haute montagne hors normes

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    Complications de la chirurgie de la cataracte. Etude retrospective de 1304 cas. [Complications of cataract surgery. Retrospective study of 1,304 cases]

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    This retrospective study concerns complications arising from 1304 first operations for cataract carried out between 1982 and 1987 by two surgeons having followed the same training and using the same techniques. Loss of vitreous (2.5%) cystoid macular edema (1.9%), and retinal detachement (1.1%) are those complications occurring most frequently in this series. Other serious complications, in descending order, are trauma (0.7%), iris prolaps (0.5%), corneal dystrophy (0.4%), pupillary block (0.3%), expulsive hemorrhage (0.15%), loss of the nucleus in the vitreous (0.07%), panophthalmia (0.07%). Secondary cataract was noted in 31% of cases

    L'astigmatisme dans la chirurgie de la cataracte. Etude retrospective de 1304 cas. [Astigmatism in cataract surgery. Retrospective study of 1,304 cases]

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    We performed a retrospective computerized study of 1304 consecutive cataract extractions, of which 251 were intracapsular and 1053 extracapsular. The analysis of surgically induced astigmatism after a mean follow-up of 22.8 months involved 639 cases. Operations were performed by two experienced surgeons using a similar and standardized technique; however the location of the incision varied without selecting patients: 391 were corneal, 248 limbal. We found that corneal incision gives significantly more against-the-rule astigmatism (average -0.61 dptr) than limbal incision (average -0.32 dptr). The suture induced astigmatism has no determining effect on the final astigmatism (correlation coefficient = 0.011). Selective suture cutting is an interesting technique for an individual dosage of the amount of final astigmatism
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