Tobamovirus evolution: gene overlaps, recombination, and taxonomic implications

Tobamoviruses, mostly isolated from solanaceous plants, may represent ancient virus lineages that have codiverged with their hosts. Recently completed nucleotide sequences of six nonsolanaceous tobamoviruses allowed assessment of the codivergence hypothesis and support a third subgroup within tobamoviruses. The genomic sequences of 12 tobamoviruses and the partial sequences of 11 others have been analyzed. Comparisons of the predicted protein sequences revealed three clusters of tobamoviruses, corresponding to those infecting solanaceous species (subgroup 1), those infecting cucurbits and legumes (subgroup 2), and those infecting crucifers. The orchid-infecting odontoglossum ringspot tobamovirus was associated with subgroup 1 genomes by its coat and movement protein sequences, but with the crucifer-pathogenic tobamoviruses by the remainder of its genome, suggesting that it is the progeny of a recombinant. For four of five genomic regions, subgroup 1 and 3 genomes were equidistant from a subgroup 2 genome chosen for comparison, suggesting uniform rates of evolution. A phylogenetic tree of plant families based on the tobamoviruses they harbor was congruent with that based on rubisco sequences but had a different root, suggesting that codivergence was tempered by rare events of viruses of one family colonizing another family. The proposed subgroup 3 viruses probably have an origin of virion assembly in the movement protein gene, a large (25-codon) overlap of movement and coat protein open reading frames, and a comparably shorter genome. Codon-position- dependent base compositions and codon prevalences suggested that the coat protein frame of the overlap region was ancestral. Bootstrapped parsimony analysis of the nucleotides in the overlap region and of the sequences translated from the -1 frame (the subgroup 3 movement protein frame) of this region produced trees inconsistent with those deduced from other regions. The results are consistent with a model in which a no or short overlap organization was ancestral. Despite encoding of subgroup 2 and 3 movement protein C-termini by nonhomologous nucleotides, weak similarities between their amino acid sequences suggested convergent sequence evolution.      

Antioxidant effects of green tea and its polyphenols on bladder cells

Genitourinary tract inflammation/ailments affect the quality of life and health of a large segment of society. In recent years, studies have demonstrated strong antioxidant effects of green tea and its associated polyphenols in inflammatory states. This in vitro study examined the antioxidant capabilities (and putative mechanisms of action) of green tea extract (GTE), polyphenon-60 (PP-60, 60% pure polyphenols), (-)-epicatechin-3-gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) in normal/malignant human bladder cells following catechin treatment+/-1 mM H2O2 (oxidative agent). Cell viability, apoptosis and reactive oxygen species (ROS) formation were evaluated. Our results showed that H2O2 exposure significantly reduced normal (UROtsa) and high-grade (TCCSUP, T24) bladder cancer (BlCa) cell viability compared with control-treated cells (p<0.001). No affect on low-grade RT4 and SW780 BlCa cell viability was observed with exposure to H2O2. Compared to H2O2-treated UROtsa, treatment with PP-60, ECG and EGCG in the presence of H2O2 significantly improved UROtsa viability (p<0.01), with strongest effects evoked by ECG. Additionally, though not as effective as in UROtsa cells, viability of both high-grade TCCSUP and T24 BlCa cells, in comparison to H2O2-treated cells, was significantly improved (p<0.01) by treatment with PP-60, ECG, and EGCG in the presence of H2O2. Overall, our findings demonstrate that urothelium cell death via H2O2-induced oxidative stress is mediated, in part, through superoxide (O2-.;), and potentially, direct H2O2 mechanisms, suggesting that green tea polyphenols can protect against oxidative stress/damage and bladder cell death.     

Insect-screened cultivation to reduce the invasion of tomato crops by Bemisia tabaci: modelling the impact on virus disease and vector

1 In two experiments carried out in Guadeloupe, barriers were used to reduce the entry of the virus vector Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) to tomato plots. The barriers erected around the crop were of insect‐proof cloth fences (<50 mesh), 1.5 m in height, in the first experiment with a deltamethrin‐treated, insect‐attracting strip facing inwards, and, in the second, with the barrier but no insecticide‐treated strip. 2 A mathematical model of epidemic development was fitted to the symptom data from the treated and control (unprotected) tomato plots. There were two viruses present, tomato yellow leaf curl and potato yellow mosaic; specific detection confirmed that symptoms gave an accurate indication of infection and that the two virus diseases had similar progress curves. 3 Parameter estimates obtained by model‐fitting suggested that the barriers reduced vector immigration by approximately 12‐fold but that B. tabaci retention within the plots was also increased slightly despite the mortality caused by the insecticide‐treated strips. Disease establishment was delayed by approximately 2 weeks. The results obtained in the second experiment involving barriers deployed without insecticide‐treated strips could be explained by a large increase in B. tabaci retention within the barriers resulting in more rapid virus disease progress than in controls. The results of mathematical modelling indicate that partial insect barriers can be worse than none because sufficient whiteflies can enter to establish a population and, at the same time, large numbers are retained in the barrier plot, with the net effect being a more rapid population increase than in the absence of barriers.     

New frontiers in the treatment of overactive bladder and incontinence

In this article the author tries to forecast how urologists will treat the overactive bladder (OAB) in the next decade. He reviews drugs currently under development and also logical and exciting pharmacological targets that would be suitable targets for treating OAB in the future. The author also discusses intravesical therapy and alternative drug delivery methods, such as intravesical capsaicin and botulinum toxin. There are many advantages to advanced drug delivery systems, including the achievement of long-term therapeutic efficacy, decreased incidence and severity of side effects, and improved patient compliance. Special emphasis is placed on approaches to modulating bladder afferent nerve function to prevent OAB. Speculation on future techniques such as gene therapy can also be considered for treating OAB, because they may make it possible to access all of the genitourinary organs via minimally invasive techniques. Traditional anticholinergic therapies are limited in their effectiveness. There is great hope for future research and therapy for OAB and urinary incontinence.