Dynamic look at DNA unwinding by a replicative helicase

A prerequisite for DNA replication is the unwinding of duplex DNA catalyzed by a replicative hexameric helicase. Despite a growing body of research, key elements of helicase mechanism remain under substantial debate. In particular, the number of DNA strands encircled by the helicase ring during unwinding and the ring orientation at the replication fork completely contrast in contemporary mechanistic models. Here we use single-molecule and ensemble assays to address these questions for the papillomavirus E1 helicase. We find that E1 unwinds DNA with a strand-exclusion mechanism, with the N-terminal side of the helicase ring facing the replication fork. We show that E1 generates strikingly heterogeneous unwinding patterns stemming from varying degrees of repetitive movements, which is modulated by the DNA-binding domain. Together, our studies reveal previously unrecognized dynamic facets of replicative helicase unwinding mechanisms

Interactions in vivo between the Vif protein of HIV-1 and the precursor (Pr55GAG) of the virion nucleocapsid proteins

The abnormality of viral core structure seen in vif-defective HIV-1 grown in PBMCs has suggested a role for Vif in viral morphogenesis. Using an in vivo mammalian two-hybrid assay, the interaction between Vif and the precursor (Pr55GAG) of the virion nucleocapsid proteins has been analysed. This revealed the amino-terminal (aa 1–22) and central (aa 70–100) regions of Vif to be essential for its interaction with Pr55GAG, but deletion of the carboxy-terminal (aa 158–192) region of the protein had only a minor effect on its interaction. Initial deletion studies carried out on Pr55GAG showed that a 35-amino-acid region of the protein bridging the MA(p17)–CA(p24) junction was essential for its ability to interact with Vif. Site-directed mutagenesis of a conserved tryptophan (Trp21) near the amino terminus of Vif showed it to be important for the interaction with Pr55GAG. By contrast, mutagenesis of the highly conserved YLAL residues forming part of the BC-box motif, shown to be important in Vif promoting degradation of APOBEC3G/3F, had little or no effect on the Vif–Pr55GAG interaction

Characterisation of Bombyx mori odorant-binding proteins reveals that a general odorant-binding protein discriminates between sex pheromone components

In many insect species, odorant-binding proteins (OBPs) are thought to be responsible for the transport of pheromones and other semiochemicals across the sensillum lymph to the olfactory receptors (ORs) within the antennal sensilla. In the silkworm Bombyx mori, the OBPs are subdivided into three main subfamilies; pheromone-binding proteins (PBPs), general odorant-binding proteins (GOBPs) and antennal-binding proteins (ABPs). We used the MotifSearch algorithm to search for genes encoding putative OBPs in B. mori and found 13, many fewer than are found in the genomes of fruit flies and mosquitoes. The 13 genes include seven new ABP-like OBPs as well as the previously identified PBPs (three), GOBPs (two) and ABPx. Quantitative examination of transcript levels showed that BmorPBP1, BmorGOBP1, BmorGOBP2 and BmorABPx are expressed at very high levels in the antennae and so could be involved in olfaction. A new two-phase binding assay, along with other established assays, showed that BmorPBP1, BmorPBP2, BmorGOBP2 and BmorABPx all bind to the B. mori sex pheromone component (10E,12Z)-hexadecadien-1-ol (bombykol). BmorPBP1, BmorPBP2 and BmorABPx also bind the pheromone component (10E,12Z)-hexadecadienal (bombykal) equally well, whereas BmorGOBP2 can discriminate between bombykol and bombykal. X-ray structures show that when bombykol is bound to BmorGOBP2 it adopts a different conformation from that found when it binds to BmorPBP1. Binding to BmorGOBP2 involves hydrogen bonding to Arg110 rather than to Ser56 as found for BmorPBP1

Factors Influencing Purchase Preferences of Store Brands: Examples from Hypermarkets in Malaysia

This study is to investigate factors that describe consumers\u27 perceptions towards store brands, and important factors that influence consumers towards purchasing store brands. The factor, such as, price, product quality, product risk, familiarity, involvement, intrinsic and extrinsic cues, and familiarity are used to gauge the purchase preferences. The study is carried out in Klang Valley involving two most popular hypermarkets in Malaysia that are Tesco and Giant. Out of 444 consumers that were intercepted and asked to participate only 300 accepted to participate and completed the questionnaire, resulting to 68% response rate. Results of the study indicate that factors such as price, familiarity, and involvement are popular in describing customers\u27 perceptions towards store brands however, only price and familiarity are the determinant in their purchasing of store brands

Bromido[(1,2,5,6-η)-cyclo­octa-1,5-diene]methyl­platinum(II)

In the title complex, [PtBr(CH3)(C8H12)], the PtII ion is in a distorted square-planar environment defined by the Br and methyl C atoms and the mid-points of the two π-coordinated double bonds of cyclo­octa-1,5-diene. As a result of the different trans influences of the Br atom and the methyl group, the Pt—C bonds trans to the methyl group [2.262 (11) and 2.261 (10) Å] are longer than those trans to the Br atom [2.118 (8) and 2.138 (9) Å]

Differentiating services: A study of hotel’s brand image

The current study examines the service brand images of hotels in Malaysia. The attraction and popularity of Malaysia as destination for tourism has created a competitive pressure among servicing sectors particularly the hotel industry to attract and maintain tourist’s loyalty to their hotels. These hotels have, and, are developing competitive marketing strategies to augment their brand images as well as to be seen as the best service provider in the country. However, little is known to understand how these hotels position their service brand images in order to be seen as such. Moreover, with regards to the service sectors, research shows that very few brands have managed to differentiate themselves from their competitors, (McDonald, de Chernatony & Harris, 2001) particularly in hotel industry. Thus, the current study examines the service brand images of hotels in Malaysia

Clinical characteristics, etiology and antimicrobial susceptibility among overweight and obese individuals with diarrhea: observed at a large diarrheal disease hospital, Bangladesh

Background:The present study aimed to determine the clinical characteristics and etiology of overweight and obese (OO) individuals with diarrhea attending an urban Dhaka Hospital, International Centre for Diarrheal Disease Research (icddr,b), Bangladesh.Methods:Total of 508 under-5 children, 96 individuals of 5-19 years and 1331 of >19 years were identified as OO from the Diarrheal Disease Surveillance System (DDSS) between 1993-2011. Two comparison groups such as well-nourished and malnourished individuals from respective age stratums were selected.Results:Isolation rate of rotavirus was higher among OO under-5 children compared to malnourished group (46% vs. 28%). Rotavirus infection among OO individuals aged 5-19 years (9% vs. 3%) (9% vs. 3%) and >19 years (6% vs. 4%) (6% vs. 3%) was higher compared to well-nourished and malnourished children. Conversely, Vibrio cholerae was lower among all OO age groups compared to well-nourished and malnourished ones. Shigella (4% vs. 6%) (4% vs. 8%), and Campylobacter (3% vs. 5%) (3% vs. 5%) were lower only among OO in >19 years individuals compared to their counterparts of the same age stratum. Salmonella was similarly isolated in all age strata and nutritional groups. In multinomial logistic regression among under-5 children, significant association was observed only with use of antimicrobials at home [OR-1.97] and duration of hospital stay [OR-0.68]. For individuals aged 5-19 years, use of antimicrobials at home (OR-1.83), some or severe dehydration (OR-3.12), having received intravenous saline (OR-0.46) and rotavirus diarrhea (OR-2.96) were found to be associated with OO respectively. Moreover, significant associations were also found for duration of diarrhea before coming to hospital (>24 hours) (OR-1.24), Shigella (OR-0.46), and Campylobacter (OR-0.58) among >19 years OO individuals along with other associated co-variates in 5-19 years group (all

Antibacterial activity of extracts from Calophyllum canum

The species of the genus Calophyllum (Guttiferae) are mainly distributed in tropical area. Plants from this genus are known as a rich source of secondary metabolite such as xanthones, coumarins, chromenes, flavonoids and triterpenoids. Some of this compounds exhibit significant biological effects antibacterial, antifungal, anti HIV and immunomodulatory activities. Calophyllum canum or Betangur baatu is a forest tree that found in Penisular of Malaysia. The research is aimed to investigate the bioactivity of C. canum extracts against selected bacteria. The chemical constituent of the plant is also investigated. The extracts are tested for their activity to inhibit the growth of Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus. The anti bacterial testing is carried out by disc diffusion method. It is concluded the C. canum has a greater potency to inhibit the growth of bacteria. The results of antibacterial of the extracts will be discussed in this paper

Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascade Inhibitors: How Mutations Can Result in Therapy Resistance and How to Overcome Resistance

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Integral components of these pathways, Ras, B-Raf, PI3K, and PTEN are also activated/inactivated by mutations. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of these pathways can contribute to chemotherapeutic drug resistance, proliferation of cancer initiating cells (CICs) and premature aging. This review will evaluate more recently described potential uses of MEK, PI3K, Akt and mTOR inhibitors in the proliferation of malignant cells, suppression of CICs, cellular senescence and prevention of aging. Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt/mTOR pathways play key roles in the regulation of normal and malignant cell growth. Inhibitors targeting these pathways have many potential uses from suppression of cancer, proliferative diseases as well as aging