Removal of hepatitis C virus-infected cells by a zymogenized bacterial toxin

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and has become a global health threat. No HCV vaccine is currently available and treatment with antiviral therapy is associated with adverse side effects. Moreover, there is no preventive therapy for recurrent hepatitis C post liver transplantation. The NS3 serine protease is necessary for HCV replication and represents a prime target for developing anti HCV therapies. Recently we described a therapeutic approach for eradication of HCV infected cells that is based on protein delivery of two NS3 protease-activatable recombinant toxins we named “zymoxins”. These toxins were inactivated by fusion to rationally designed inhibitory peptides via NS3-cleavable linkers. Once delivered to cells where NS3 protease is present, the inhibitory peptide is removed resulting in re-activation of cytotoxic activity. The zymoxins we described suffered from two limitations: they required high levels of protease for activation and had basal activities in the un-activated form that resulted in a narrow potential therapeutic window. Here, we present a solution that overcame the major limitations of the “first generation zymoxins” by converting MazF ribonuclease, the toxic component of the E. coli chromosomal MazEF toxin-antitoxin system, into an NS3-activated zymoxin that is introduced to cells by means of gene delivery. We constructed an expression cassette that encodes for a single polypeptide that incorporates both the toxin and a fragment of its potent natural antidote, MazE, linked via an NS3-cleavable linker. While covalently paired to its inhibitor, the ribonuclease is well tolerated when expressed in naïve, healthy cells. In contrast, activating proteolysis that is induced by even low levels of NS3, results in an eradication of NS3 expressing model cells and HCV infected cells. Zymoxins may thus become a valuable tool in eradicating cells infected by intracellular pathogens that express intracellular proteases.     

Microbial rhodopsins on leaf surfaces of terrestrial plants

The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 10(26) microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point towards the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.     

Identification of novel snRNA-specific Sm proteins that bind selectively to U2 and U4 snRNAs in Trypanosoma brucei

In eukaryotes the seven Sm core proteins bind to U1, U2, U4, and U5 snRNAs. In Trypanosoma brucei, Sm proteins have been implicated in binding both spliced leader (SL) and U snRNAs. In this study, we examined the function of these Sm proteins using RNAi silencing and protein purification. RNAi silencing of each of the seven Sm genes resulted in accumulation of SL RNA as well as reduction of several U snRNAs. Interestingly, U2 was unaffected by the loss of SmB, and both U2 and U4 snRNAs were unaffected by the loss of SmD3, suggesting that these snRNAs are not bound by the heptameric Sm complex that binds to U1, U5, and SL RNA. RNAi silencing and protein purification showed that U2 and U4 snRNAs were bound by a unique set of Sm proteins that we termed SSm (specific spliceosomal Sm proteins). This is the first study that identifies specific core Sm proteins that bind only to a subset of spliceosomal snRNAs.     

A Novel ROP/RAC effector links cell polarity, root-meristem maintenance, and vesicle trafficking

ROP/RAC GTPases are master regulators of cell polarity in plants, implicated in the regulation of diverse signaling cascades including cytoskeleton organization, vesicle trafficking, and Ca(2+) gradients [1-8]. The involvement of ROPs in differentiation processes is yet unknown. Here we show the identification of a novel ROP/RAC effector, designated interactor of constitutive active ROPs 1 (ICR1), that interacts with GTP-bound ROPs. ICR1 knockdown or silencing leads to cell deformation and loss of root stem-cell population. Ectopic expression of ICR1 phenocopies activated ROPs, inducing cell deformation of leaf-epidermis-pavement and root-hair cells [3, 5, 6, 9]. ICR1 is comprised of coiled-coil domains and forms complexes with itself and the exocyst vesicle-tethering complex subunit SEC3 [10-13]. The ICR1-SEC3 complexes can interact with ROPs in vivo. Plants overexpressing a ROP- and SEC3-noninteracting ICR1 mutant have a wild-type phenotype. Taken together, our results show that ICR1 is a scaffold-mediating formation of protein complexes that are required for cell polarity, linking ROP/RAC GTPases with vesicle trafficking and differentiation.     

The reasons for tooth loss in geriatric patients attending two surgical clinics in Jerusalem,Israel.

Abstract Objectives Numerous studies around the world have been conducted in order to understand the reasons for tooth extractions in various age groups. Most studies have dealt with the general adult population but little attention has been paid to the elderly population. In Israel, as in most of the western countries, the elderly population is growing rapidly and thus demands for its dental needs are also increasing. In order to meet the dental requirements of the geriatric population, data on the main reasons of tooth mortality have been collected. Design Retrospective analysis of reasons for extraction divided into three categories: caries, periodontal disease and “other’’. Subjects The files of 302 consecutive elderly patients aged 65-95 years attending for extraction. The cause for tooth extraction was gathered from the written diagnosis described by the operator as well as from radiographs. Setting Two surgical clinics in Jerusalem serving low income residents. Results Results indicated that 30% of the extractions were due to caries, 65% were due to periodontal disease and only 6.4% related to “other’’ reasons. In both, males and females, periodontal disease was the major cause for tooth loss yet, females exhibited more extractions due to caries than males (35%vs 23% respectively). A relatively high incidence of tooth loss was documented for the 85+ age group. Of the teeth that were extracted, incisors and molars were equally the most frequent (29%) followed by premolars (26%) and canines (17%). Premolars were the teeth most frequently extracted out of the teeth removed due to caries (32%) whereas incisors were the most frequently removed within the group of teeth extracted due to periodontal disease (31%). Conclusions The results of this study point to the importance of prevention and treatment of dental diseases, particularly periodontal disease, in adults aged 0 years and above in order to prevent tooth loss in their later years.     

Association between concentration of trace elements in serum and bronchial asthma among Japanese general population

Background and aimsA number of previous studies had revealed the association between trace elements in serum and bronchial asthma. However, only a few researches had focused on serum concentration of trace elements in a general population. In this study, an association between trace elements in serum and bronchial asthma was investigated in a general population.MethodsSubjects were 1025 volunteers (385 males and 640 females between ages 19 and 82 years old) who had participated in the Iwaki Health Promotion Project 2005. Bronchial asthma was diagnosed based on the European Community Respiratory Health Survey II according to the self-questionnaires on health conditions of subjects. The serum concentrations of certain trace elements (manganese, copper, zinc, selenium and iron) were measured and compared. Also, an association between serum trace elements level and neutrophil-related functions (oxidative burst activity, phagocytic activity, serum opsonic activity) were determined.ResultsIn males, no significant differences were seen in any serum trace elements concentrations. In females, serum zinc level was significantly higher in bronchial asthma group than in control. A positive correlation was seen between serum concentration of zinc and serum opsonic activity in both genders.ConclusionsIn female asthmatics, increase of oxidative stress was suggested to be caused by superoxide dismutase pathway (elimination system of reactive oxygen species) rather than serum opsonic activity (production system of reactive oxygen species from neutrophils) pathway, as the zinc concentration in bronchial asthma group was higher than that in control.     

Effect of Ferricyanide on Potassium Uptake by Intact Epidermal Tissue and Guard Cell Protoplasts

The effect of ferricyanide on K^$ fluxes in epidermis and inguard cells of Commelina communis L. were studied. Ferricyanideenhanced guard cell protoplasts swelling, which results fromenhanced K^$ uptake. In intact epidermis ferricyanide inhibitedK^$ uptake and consequently, stomatal opening. This was foundin floated and submerged epidermal tissues, indicating thatthe degree of contact with the solution does not affect theresponse to ferricyanide. Investigation of the rate of plasmolysisand de-plasmolysis of guard cells in epidermal tissue revealedthat ferricyanide enhances deplasmolysis, caused by K^$ uptake,only in completely plasmolysed cells, which resemble protoplastsin situ. (Received January 21, 1988; Accepted March 24, 1988)