NS1643 Interacts around L529 of hERG to Alter Voltage Sensor Movement on the Path to Activation

Activators of hERG1 such as NS1643 are being developed for congenital/acquired long QT syndrome. Previous studies identify the neighborhood of L529 around the voltage-sensor as a putative interacting site for NS1643. With NS1643, the V_1/2 of activation of L529I (−34 ± 4 mV) is similar to wild-type (WT) (−37 ± 3 mV; P > 0.05). WT and L529I showed no difference in the slope factor in the absence of NS1643 (8 ± 0 vs. 9 ± 0) but showed a difference in the presence of NS1643 (9 ± 0.3 vs. 22 ± 1; P < 0.01). Voltage-clamp-fluorimetry studies also indicated that in L529I, NS1643 reduces the voltage-sensitivity of S4 movement. To further assess mechanism of NS1643 action, mutations were made in this neighborhood. NS1643 shifts the V_1/2 of activation of both K525C and K525C/L529I to hyperpolarized potentials (−131 ± 4 mV for K525C and −120 ± 21 mV for K525C/L529I). Both K525C and K525C/K529I had similar slope factors in the absence of NS1643 (18 ± 2 vs. 34 ± 5, respectively) but with NS1643, the slope factor of K525C/L529I increased from 34 ± 5 to 71 ± 10 (P < 0.01) whereas for K525C the slope factor did not change (18 ± 2 at baseline and 16 ± 2 for NS1643). At baseline, K525R had a slope factor similar to WT (9 vs. 8) but in the presence of NS1643, the slope factor of K525R was increased to 24 ± 4 vs. 9 ± 0 mV for WT (P < 0.01). Molecular modeling indicates that L529I induces a kink in the S4 voltage-sensor helix, altering a salt-bridge involving K525. Moreover, docking studies indicate that NS1643 binds to the kinked structure induced by the mutation with a higher affinity. Combining biophysical, computational, and electrophysiological evidence, a mechanistic principle governing the action of some activators of hERG1 channels is proposed.     

Kinetochore dynein is required for chromosome motion and congression independent of the spindle checkpoint

During mitosis, the motor molecule cytoplasmic dynein plays key direct and indirect roles in organizing microtubules (MTs) into a functional spindle. At this time, dynein is also recruited to kinetochores, but its role or roles at these organelles remain vague, partly because inhibiting dynein globally disrupts spindle assembly [1-4]. However, dynein can be selectively depleted from kinetochores by disruption of ZW10 [5], and recent studies with this approach conclude that kinetochore-associated dynein (KD) functions to silence the spindle-assembly checkpoint (SAC) [6]. Here we use dynein-antibody microinjection and the RNAi of ZW10 to explore the role of KD in chromosome behavior during mitosis in mammals. We find that depleting or inhibiting KD prevents the rapid poleward motion of attaching kinetochores but not kinetochore fiber (K fiber) formation. However, after kinetochores attach to the spindle, KD is required for stabilizing kinetochore MTs, which it probably does by generating tension on the kinetochore, and in its absence, chromosome congression is defective. Finally, depleting KD reduces the velocity of anaphase chromosome motion by approximately 40%, without affecting the rate of poleward MT flux. Thus, in addition to its role in silencing the SAC, KD is important for forming and stabilizing K fibers and in powering chromosome motion.     

Termites and Chinese agricultural system: applications and advances in integrated termite management and chemical control

Termites are eusocial arthropod decomposers,and improve soil fertility,crop yield,and also are used by humans for their ben efits across the world.However,some species of termites are becoming a threat to the farming community as they are directly and indirectly causing major losses to the agricultural system.It is estimated that termites cost the global economy more than 40 billion USD annually,and considerable research has been done on their management.In this review,we present the available information related to sustainable and integrated termite management practices(ITM).Furthermore,we insist that the better management of this menace can be possible through:(i)improving traditional methods to keep termites away from crops;(ii)improving agricultural practices to maintain plants with more vigor and less susceptible to termite attack;and(iii)integration of available techniques to reduce termite infestation in crops and surroundings.The application of an effective combination of traditional practices with recently developed approaches is the best option for agricultural growers.Moreover,keeping in mind the beneficial nature of this pest,more innovative efforts for its management,particularly using rapidly emerging technology(e.g.,RNA interference),are needed.     

DNA cleavage by homo- and heterotetranuclear Cu(II) and Mn(II) complexes with tetrathioether-tetrathiol moiety

Novel homotetranuclear Cu(II) and heteronuclear Cu(II)-Mn(II) complexes with tetrathioether-tetrathiol moiety have been prepared and their DNA relaxation activities with plasmid pCYTEXP (5kb) were electrophoretically established. The cleavage products analyzed by neutral agarose gel electrophoresis indicated that the interaction of the metal complexes with supercoiled plasmid DNA yielded linear, nicked or degraded DNA. The relaxation activities of both homo- and heterotetranuclear (SK4) complexes are time- and concentration-dependent. The findings suggest that SK4 with potent nucleolytic activity is a good nuclease substitute in the presence of cooxidant. Furthermore, the observation of induction of DNA into smaller fragments by SK4 is also significant.     

Effects of red wine consumption on serum paraoxonase/arylesterase activities and on lipoprotein oxidizability in healthy-men

Although there is a general consensus concerning the lower risk for cardiovascular disease in moderate drinkers, the mechanisms responsible for the cardioprotective effect of red wine remain unknown. It has been proposed that increased serum paraoxonase activity may be a mechanism of action underlying reduced cardiovascular disease risk in moderate drinkers, since paraoxonase inhibits lipoprotein oxidation. The aim of this study was to investigate the effects of red wine consumption on serum paraoxonase/arylesterase activities and on lipoprotein oxidizability in healthy-men. Fourteen healthy-men were included in the study. The subjects consumed 0.375 g alcohol / kg body weight for 3 weeks. Paraoxonase and arylesterase activities were studied spectrophotometrically. Oxidizability of apolipoprotein B-containing lipoproteins were determined, after separating them with precipitation method, by incubating with copper-sulfate. Paraoxonase activity did not change, however arylesterase activity significantly decreased after red wine consumption (P < 0.01). There was a reduced susceptibility of apolipoprotein B-containing lipoproteins to copper-sulfate induced oxidation after red wine consumption (P < 0.01). Our results support that red wine protects lipoproteins against oxidation, however there was not any significant change in serum paraoxonase activity after red wine consumption.KEY WORDS: Red wine; Paraoxonase; Arylesterase; Lipoprotein oxidation     

Genome Wide Association Studies Using a New Nonparametric Model Reveal the Genetic Architecture of 17 Agronomic Traits in an Enlarged Maize Association Panel

Association mapping is a powerful approach for dissecting the genetic architecture of complex quantitative traits using high-density SNP markers in maize. Here, we expanded our association panel size from 368 to 513 inbred lines with 0.5 million high quality SNPs using a two-step data-imputation method which combines identity by descent (IBD) based projection and k-nearest neighbor (KNN) algorithm. Genome-wide association studies (GWAS) were carried out for 17 agronomic traits with a panel of 513 inbred lines applying both mixed linear model (MLM) and a new method, the Anderson-Darling (A-D) test. Ten loci for five traits were identified using the MLM method at the Bonferroni-corrected threshold −log₁₀ (P) >5.74 (α = 1). Many loci ranging from one to 34 loci (107 loci for plant height) were identified for 17 traits using the A-D test at the Bonferroni-corrected threshold −log₁₀ (P) >7.05 (α = 0.05) using 556809 SNPs. Many known loci and new candidate loci were only observed by the A-D test, a few of which were also detected in independent linkage analysis. This study indicates that combining IBD based projection and KNN algorithm is an efficient imputation method for inferring large missing genotype segments. In addition, we showed that the A-D test is a useful complement for GWAS analysis of complex quantitative traits. Especially for traits with abnormal phenotype distribution, controlled by moderate effect loci or rare variations, the A-D test balances false positives and statistical power. The candidate SNPs and associated genes also provide a rich resource for maize genetics and breeding.     

Contrasting phylogeography of two Western Palaearctic fish parasites despite similar life cycles

Aim

We used comparative phylogeography of two intestinal parasites of freshwater fish to test whether similarity in life cycle translates into concordant phylogeographical history. The thorny‐headed worms Pomphorhynchus laevis and P. tereticollis (Acanthocephala) were formerly considered as a single species with a broad geographical and host range within the Western Palaearctic.

Location

Central and eastern parts of Northern Mediterranean area, Western and Central Europe, Ponto‐Caspian Europe.

Methods

A mitochondrial marker (COI) was sequenced for 111 P. laevis and 50 P. tereticollis individuals and nuclear ITS1 and ITS2 sequences were obtained for 37 P. laevis and 21 P. tereticollis. Genetic divergence, phylogenetic relationships and divergence time were estimated for various lineages within each species, and their phylogeographical patterns were compared to known palaeogeographical events in Western Palaearctic. Biogeographical histories of each species were inferred.

Results

The two species show very different phylogeographical patterns. Five lineages were identified in P. laevis, partially matching several major biogeographical regions defined in the European riverine fish fauna. The early stages of P. laevis diversification occurred in the peri‐Mediterranean area, during the Late Miocene. Subsequent expansion across Western Europe and Russia was shaped by dispersal and vicariant events, from Middle Pliocene to Middle Pleistocene. By contrast, P. tereticollis has differentiated more recently within the Western and Central parts of Europe, and shows weak geographical and genetic structuring.

Conclusion

Our study highlights weak to moderate similarity in the phylogeographical pattern of these acanthocephalan parasites compared to their amphipod and fish hosts. The observed differences in the timing of dispersion and migration routes taken may reflect the use of a range of final hosts with different ecologies and dispersal capabilities. By using a group underrepresented in phylogeographical studies, our study is a valuable contribution to revealing the biogeography of host–parasite interactions in continental freshwaters.