Identification of a discrete intermediate in the assembly/disassembly of physalis mottle tymovirus through mutational analysis.

Assembly intermediates of icosahedral viruses are usually transient and are difficult to identify. In the present investigation, site-specific and deletion mutants of the coat protein gene of physalis mottle tymovirus (PhMV) were used to delineate the role of specific amino acid residues in the assembly of the virus and to identify intermediates in this process. N-terminal 30, 34, 35 and 39 amino acid deletion and single C-terminal (N188) deletion mutant proteins of PhMV were expressed in Escherichia coli. Site-specific mutants H69A, C75A, W96A, D144N, D144N-T151A, K143E and N188A were also constructed and expressed. The mutant protein lacking 30 amino acid residues from the N terminus self-assembled to T=3 particles in vivo while deletions of 34, 35 and 39 amino acid residues resulted in the mutant proteins that were insoluble. Interestingly, the coat protein (pR PhCP) expressed using pRSET B vector with an additional 41 amino acid residues at the N terminus also assembled into T=3 particles that were more compact and had a smaller diameter. These results demonstrate that the amino-terminal segment is flexible and either the deletion or addition of amino acid residues at the N terminus does not affect T=3 capsid assembly. In contrast, the deletion of even a single residue from the C terminus (PhN188Delta1) resulted in capsids that were unstable. These capsids disassembled to a discrete intermediate with a sedimentation coefficent of 19.4 S. However, the replacement of C-terminal asparagine 188 by alanine led to the formation of stable capsids. The C75A and D144N mutant proteins also assembled into capsids that were as stable as the pR PhCP, suggesting that C75 and D144 are not crucial for the T=3 capsid assembly. pR PhW96A and pR PhD144N-T151A mutant proteins failed to form capsids and were present as heterogeneous aggregates. Interestingly, the pR PhK143E mutant protein behaved in a manner similar to the C-terminal deletion protein in forming unstable capsids. The intermediate with an s value of 19.4 S was the major assembly product of pR PhH69A mutant protein and could correspond to a 30mer. It is possible that the assembly or disassembly is arrested at a similar stage in pR PhN188Delta1, pR PhH69A and pR PhK143E mutant proteins.     

Legacies in Switchgrass Resistance to and Recovery from Drought Suggest That Good Years Can Sustain Plants Through Bad Years

The warm-season perennial switchgrass (Panicum virgatum) is a candidate bioenergy crop. To be successful, switchgrass production must be maintained on low-quality landscapes with minimal inputs while facing future climates that are expected to be more extreme and more variable. We propose that antecedent rainfall constrains how plants respond to drought, as well as subsequently recover from drought. To test this idea, we examined how six switchgrass genotypes responded to a 1-year severe drought and then recovered under normal rainfall in the following year. These plants had previously grown for 3 years under a range of dry to wet rainfall levels in a shallow-soil common garden with no fertilizer. Plants previously exposed to drought produced less biomass, and basal area after the severe drought was relieved compared to previously well-watered plants. In addition, there were legacy effects caused by plant size: plants that were larger pre-drought were more likely to survive the severe drought, and plants that were larger during the severe drought recovered more biomass, basal area, and tillers post-drought. Although genotypes differed somewhat in their responses, the size constraint was consistent across genotypes. These findings suggest that we can establish more drought-resilient switchgrass stands by, for example, planning for initial irrigation or planting during a wet year to allow plants to grow larger prior to experiencing drought. Additional studies are needed to understand whether these rainfall and size legacies persist or are transient.     

Synthesis and pharmacological evaluation of aryl aminosulfonamide derivatives as potent 5-HT6 receptor antagonists

A series of novel aryl aminosulfonamides was designed and synthesized as 5-HT₆ receptor ligands. Many compounds screened in a functional reporter gene based assay displayed potent antagonistic activity with Kb values in the range of 0.02–10 nM. The lead compound 11m exemplified in this series showed good ADME surrogate properties, acceptable pharmacokinetic profile and is active in animal models of cognition like novel object recognition test and Morris water maze. The compound was selected for detailed profiling.     

Effect of slice thickness on brain magnetic resonance image texture analysis

Background  

The accuracy of texture analysis in clinical evaluation of magnetic resonance images depends considerably on imaging arrangements and various image quality parameters. In this paper, we study the effect of slice thickness on brain tissue texture analysis using a statistical approach and classification of T1-weighted images of clinically confirmed multiple sclerosis patients.     

Ecoepidemiology,short history and control of Chagas disease in the endemic countries and the new challenge for non-endemic countries

Chagas disease is maintained in nature through the interchange of three cycles: the wild, peridomestic and domestic cycles. The wild cycle, which is enzootic, has existed for millions of years maintained between triatomines and wild mammals. Human infection was only detected in mummies from 4,000-9,000 years ago, before the discovery of the disease by Carlos Chagas in 1909. With the beginning of deforestation in the Americas, two-three centuries ago for the expansion of agriculture and livestock rearing, wild mammals, which had been the food source for triatomines, were removed and new food sources started to appear in peridomestic areas: chicken coops, corrals and pigsties. Some accidental human cases could also have occurred prior to the triatomines in peridomestic areas. Thus, triatomines progressively penetrated households and formed the domestic cycle of Chagas disease. A new epidemiological, economic and social problem has been created through the globalisation of Chagas disease, due to legal and illegal migration of individuals infected by Trypanosoma cruzi or presenting Chagas disease in its varied clinical forms, from endemic countries in Latin America to non-endemic countries in North America, Europe, Asia and Oceania, particularly to the United States of America and Spain. The main objective of the present paper was to present a general view of the interchanges between the wild, peridomestic and domestic cycles of the disease, the development of T. cruzi among triatomine, their domiciliation and control initiatives, the characteristics of the disease in countries in the Americas and the problem of migration to non-endemic countries.     

The effect of acidification and the combined effects of acidification/lipid extraction on carbon stable isotope ratios for sub-arctic and arctic marine zooplankton species

Stable isotope ratios of carbon (δ ¹³C) in zooplankton are widely applied in ecosystem-level studies of energy flux and trophic interactions. Carbonate (CaCO₃) and lipid content are highly variable both among and within zooplankton species. Such variability can arise from the δ ¹³C-depleted nature of lipids as well as differences in carbon incorporation among tissues (e.g., relative amount of carbonate). Critically, the impact of the common lipid- and carbonate-normalization steps of extraction and acidification is poorly understood and applied in an inconsistent manner. Here, we investigated the effect of lipid extraction and sample acidification (CaCO₃ removal) on δ ¹³C in sub-arctic and arctic marine zooplankton species. Our results indicate that, with the exception of the shelled mollusc Limacina helicina, acidification of samples can be omitted for all other marine zooplankton considered in this study. In the case of L. helicina, δ ¹³C can be corrected for carbonate content using the linear equation developed in this study. In contrast, the δ ¹³C for all species was significantly enriched by a combination of lipid extraction and acidification (up to +4.9 ‰) prior to stable isotope analysis. Our data were used to develop simple, predictive species-specific correction models for lipid-acid-normalized δ ¹³C using C:N and/or untreated δ ¹³C values. Our results indicate that the δ ¹³C value for all species, including those with lower C:N ratios (~3–4), should be corrected for lipid content. We recommend lipid extraction whenever possible, or else the use of species/taxon-specific δ ¹³C lipid-normalization models for accurate determination of carbon sources and dynamics for arctic and sub-arctic marine zooplankton.     

Information propagation within the Genetic Network of Saccharomyces cerevisiae

Background  

A gene network's capacity to process information, so as to bind past events to future actions, depends on its structure and logic. From previous and new microarray measurements in Saccharomyces cerevisiae following gene deletions and overexpressions, we identify a core gene regulatory network (GRN) of functional interactions between 328 genes and the transfer functions of each gene. Inferred connections are verified by gene enrichment.     

Protein biomarkers for in vitro testing of embryotoxicity

There are new challenges for hazard and risk assessment in the chemical industry with regard to REACH legislation in Europe and related activities in the U.S. and Japan, which require the development of novel in vitro models for the molecular characterization of drug- or chemical-related effects replacing conventional animal testing. In the frame of a European FP6 project on reproductive toxicology ( www.reprotect.eu ), we prepared protein samples from mouse embryonic stem cells differentiated into contracting cardiomyocytes according to the validated embryonic stem cell test (EST) protocol, which had been exposed to toxic substances selected by an expert committee from different in vivo categories of embryotoxicity. Lysates were used to carry out the following investigations: (i) identify optimal dose range conditions in the EST that are suitable for (ii) performing a differential quantitative proteomic study of underlying molecular pathways, (iii) define classes of substances with similar proteomic response patterns, (iv) relate these classes to the traditional in vivo categories of embryotoxicity with (v) the final goal to identify novel surrogate protein biomarker candidates for embryo toxicity. We found two distinct classes of toxic substances (Dinoseb, Ochratoxin-A, and Nitrofen vs β-aminoproprionitril, Metoclopramide, Doxylamine succinate, and d-penicillamine) with clear pathway-related differences in their proteomic patterns. Most notably, different responses to cluster 1 and cluster 2 substances were observed for Heat shock protein β-1, Ras-GTPase-activating protein SH3-domain binding protein, Ran binding protein 5, and Calreticulin, Dihydropyrimidinase-like 2 (Ulip2 protein). On the other hand, Heat shock protein 8 and Fscn1 protein were down-regulated by all compounds from both clusters.