The MID-PIWI module of Piwi proteins specifies nucleotide- and strand-biases of piRNAs

Piwi-interacting RNAs (piRNAs) guide Piwi Argonautes to suppress transposon activity in animal gonads. Known piRNA populations are extremely complex, with millions of individual sequences present in a single organism. Despite this complexity, specific Piwi proteins incorporate piRNAs with distinct nucleotide- and transposon strand-biases (antisense or sense) of unknown origin. Here, we examined the contribution of structural domains in Piwi proteins toward defining these biases. We report the first crystal structure of the MID domain from a Piwi Argonaute and use docking experiments to show its ability to specify recognition of 5′ uridine (1U-bias) of piRNAs. Mutational analyses reveal the importance of 5′ end-recognition within the MID domain for piRNA biogenesis in vivo. Finally, domain-swapping experiments uncover an unexpected role for the MID-PIWI module of a Piwi protein in dictating the transposon strand-orientation of its bound piRNAs. Our work identifies structural features that allow distinguishing individual Piwi members during piRNA biogenesis.     

Isolation and characterization of luciferase from Indian firefly,Luciola praeusta

Luciferase from Indian firefly Luciola praeusta (Coleoptera: Lampyridae: Luciolinae) was isolated and the properties compared with that of the North American firefly, Photinus pyralis. Luciola praeusta luciferase was purified using acetone extraction, gel‐filtration column chromatography, ammonium sulfate precipitation and anion exchange chromatography. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis indicates a homogeneous preparation and the molecular mass was slightly higher than that of Photinus pyralis. The effect of pH, buffer composition and metal ions on the spectral characteristics was studied. The maximum bioluminescence activity of luciferase was observed in ACES buffer at pH 6.5. The emission maximum of 562 nm (in crude extract) was red shifted to 570 nm in Tricine buffer at pH 7.8. In addition, the effect of bovine serum albumin on the storage stability of the protein was investigated. Based on the unique spectral characteristics observed, we propose that Luciola praeusta luciferase in the native form is suitable for the assay of biochemical metabolites in acidic pH. Copyright © 2013 John Wiley & Sons, Ltd.     

Language Universals Engage Broca's Area

It is well known that natural languages share certain aspects of their design. For example, across languages, syllables like blif are preferred to lbif. But whether language universals are myths or mentally active constraints—linguistic or otherwise—remains controversial. To address this question, we used fMRI to investigate brain response to four syllable types, arrayed on their linguistic well-formedness (e.g., blif≻bnif≻bdif≻lbif, where ≻ indicates preference). Results showed that syllable structure monotonically modulated hemodynamic response in Broca''s area, and its pattern mirrored participants'' behavioral preferences. In contrast, ill-formed syllables did not systematically tax sensorimotor regions—while such syllables engaged primary auditory cortex, they tended to deactivate (rather than engage) articulatory motor regions. The convergence between the cross-linguistic preferences and English participants'' hemodynamic and behavioral responses is remarkable given that most of these syllables are unattested in their language. We conclude that human brains encode broad restrictions on syllable structure.     

Effect of Pregnancy on Anti-HEV Antibody Titres,Plasma Cytokines and the Corresponding Gene Expression Levels in the PBMCs of Patients Presenting with Self-Recovering Clinical and Subclinical Hepatitis E

High mortality in pregnant women (PR) is a characteristic of hepatitis E in developing countries. To understand the pathogenesis of HEV infection in self-limiting disease during pregnancy, we compared clinical (PR-patients) and subclinical-HEV-infections in pregnant women in the first (SC-PR-1) and later (2nd and 3rd, SC-PR-2+3) trimesters with the respective healthy controls and acute non-PR patients. The SC-PR-2+3 exhibited lower ALT, bilirubin levels, anti-HEV-IgM/IgG titres than the acute-PR/non-PR-patients (p<0.05–0.0001). IFNγ/IL4ratios indicated Th2/Th1 bias in non-PR and PR-patients respectively. Raised levels of 10/20 plasma cytokines in the non-PR-patients reflect predominant inflammatory response, unaltered- IFNγ/reduced-IFNα responses and a robust chemokine secretion. On contrary, the acute-PR-patients exhibited drastic reduction in majority of the cytokines relative to in the non-PR-patients. Importantly, diminished or unaltered response was noted in the acute-PR-group when compared to the corresponding controls. The only exception was sIL2RA, increasing in both patient categories. Of the 14 genes evaluated, the expression of IFNγ/IL10/IL1A/IL7/CCL2/CCL3/CXCL8/CXCL10 was higher in the non-PR patients. Of these, the expression of IFNγ/IL10/IL1A/CCL2/CCL3/CXCL8 and, additionally, IL2/IL6/TNF genes was higher in the clinical-PRs. Almost identical pattern was noted in the control-PR-2+3 category indicating no influence of HEV infection. Comparison of patient-categories identified significant elevation of IFNγ(P<0.001), CCL2(p<0.01), CXCL8(P<0.05), IL1B(p<0.05) and IL10(P<0.0001) and decrease in CXCL10(<0.05) in the PR-patients. The results suggest antibody-dependent disease severity and impaired immune response in the PR patients. Higher expression of cytokine-genes in the PBMCs did not correlate with the plasma-cytokine levels in the PR-patients.     

Inhibition or Knockdown of ABC Transporters Enhances Susceptibility of Adult and Juvenile Schistosomes to Praziquantel

Parasitic flatworms of the genus Schistosoma cause schistosomiasis, a neglected tropical disease that affects hundreds of millions. Treatment of schistosomiasis depends almost entirely on the drug praziquantel (PZQ). Though essential to treating and controlling schistosomiasis, a major limitation of PZQ is that it is not active against immature mammalian-stage schistosomes. Furthermore, there are reports of field isolates with heritable reductions in PZQ susceptibility, and researchers have selected for PZQ-resistant schistosomes in the laboratory. P-glycoprotein (Pgp; ABCB1) and other ATP binding cassette (ABC) transporters remove a wide variety of toxins and xenobiotics from cells, and have been implicated in multidrug resistance (MDR). Changes in ABC transporter structure or expression levels are also associated with reduced drug susceptibility in parasitic helminths, including schistosomes. Here, we show that the activity of PZQ against schistosome adults and juveniles ex vivo is potentiated by co-administration of either the highly potent Pgp inhibitor tariquidar or combinations of inhibitors targeting multiple ABC multidrug transporters. Adult worms exposed to sublethal PZQ concentrations remain active, but co-administration of ABC transporter inhibitors results in complete loss of motility and disruption of the tegument. Notably, juvenile schistosomes (3–4 weeks post infection), normally refractory to 2 µM PZQ, become paralyzed when transporter inhibitors are added in combination with the PZQ. Experiments using the fluorescent PZQ derivative (R)-PZQ-BODIPY are consistent with the transporter inhibitors increasing effective intraworm concentrations of PZQ. Adult worms in which expression of ABC transporters has been suppressed by RNA interference show increased responsiveness to PZQ and increased retention of (R)-PZQ-BODIPY consistent with an important role for these proteins in setting levels of PZQ susceptibility. These results indicate that parasite ABC multidrug transporters might serve as important targets for enhancing the action of PZQ. They also suggest a potentially novel and readily-available strategy for overcoming reduced PZQ susceptibility of schistosomes.     

Discovering Protein Interactions and Characterizing Protein Function Using HaloTag Technology

Research in proteomics has exploded in recent years with advances in mass spectrometry capabilities that have led to the characterization of numerous proteomes, including those from viruses, bacteria, and yeast.  In comparison, analysis of the human proteome lags behind, partially due to the sheer number of proteins which must be studied, but also the complexity of networks and interactions these present. To specifically address the challenges of understanding the human proteome, we have developed HaloTag technology for protein isolation, particularly strong for isolation of multiprotein complexes and allowing more efficient capture of weak or transient interactions and/or proteins in low abundance.  HaloTag is a genetically encoded protein fusion tag, designed for covalent, specific, and rapid immobilization or labelling of proteins with various ligands. Leveraging these properties, numerous applications for mammalian cells were developed to characterize protein function and here we present methodologies including: protein pull-downs used for discovery of novel interactions or functional assays, and cellular localization. We find significant advantages in the speed, specificity, and covalent capture of fusion proteins to surfaces for proteomic analysis as compared to other traditional non-covalent approaches. We demonstrate these and the broad utility of the technology using two important epigenetic proteins as examples, the human bromodomain protein BRD4, and histone deacetylase HDAC1.  These examples demonstrate the power of this technology in enabling  the discovery of novel interactions and characterizing cellular localization in eukaryotes, which will together further understanding of human functional proteomics.                   

Synthesis and biological evaluation of [4-(2-phenylethenesulfonylmethyl)phenyl]-quinazolin-4-yl-amines as orally active anti-cancer agents

A new series of [4-(2-phenylethenesulfonylmethyl)phenyl]quinazolin-4-yl-amines was prepared and tested for its in vitro cytotoxic activity against a panel of 12 human cancer cell lines. Compounds 9, 15, 24 and 31 showed good in vitro activity and were further tested for their in vivo efficacy in the HT-29 human colon adeno carcinoma xenograft model. Compound 9 exhibited promising activity in this model. Dose-response studies for this compound against HT-29 human colon adeno carcinoma xenografts at 100, 200 and 400mg/kg doses were performed.