Review ["Telling the Evolutionary Time : Molecular Clocks and the Fossil Record" edited by Philip C. J. Donoghue and M. Paul Smith]

Determining the temporal scale of biological evolution has traditionally been the preserve of paleontology, with the timing of species originations and major diversifications all being read from the fossil record. However, the ages of the earliest (correctly identified) records will underestimate actual origins due to the incomplete nature of the fossil record and the necessity for lineages to have evolved sufficiently divergent morphologies in order to be distinguished. The possibility of inferring divergence times more accurately has been promoted by the idea that the accumulation of genetic change between modern lineages can be used as a molecular clock (Zuckerkandl and Pauling, 1965). In practice, though, molecular dates have often been so old as to be incongruent even with liberal readings of the fossil record. Prominent examples include inferred diversifications of metazoan phyla hundreds of millions of years before their Cambrian fossil record appearances (e.g., Nei et al., 2001) and a basal split between modern birds (Neoaves) that is almost double the age of their earliest recognizable fossils (e.g., Cooper and Penny, 1997).

Book review: "English for telecoms and information technology" by T. Ricca and M. Duckworth; "English for legal professionals" by A. Frost; "English for the pharmaceutical industry" by M. Buchler, K. Jaehnig, G. Matzig, and T. Weindler; "English for cabin crews" by S. Ellis and L. Lansford; and "English for negotiating" by C. Lafond, S. Vine, and B. Welch.

This review examines five books in the Oxford Business English Express Series, including "English for telecoms and information technology" by T. Ricca and M. Duckworth; "English for legal professionals" by A. Frost; "English for the pharmaceutical industry" by M. Buchler, K. Jaehnig, G. Matzig, and T. Weindler; "English for cabin crews" by S. Ellis and L. Lansford; and "English for negotiating" by C. Lafond, S. Vine, and B. Welch.

The adenine-rich tract in the 5ʹ-end of the hepatitis C virus ORF encodes a peptide regulating the binding of the C protein to RNA

Hepatitis C virus (HCV ) core (C) protein is thought to bind to viral RNA before it undergoes oligomerization leading to RNA encapsidation. Details of these events are so far unknown. The 5ʹ-terminal C protein coding sequence that includes an adenine (A)-rich tract is a part of an internal ribosome entry site(IRES). This nucleotide sequence but not the corresponding protein sequence is needed for proper initiation of translation of viral RNA by an IRES-dependent mechanism. In this study, we examined the importance of this sequence for the ability of the C protein to bind to viral RNA. Serially truncated C proteins with deletions from 10 up to 45 N-terminal amino acids were expressed in Escherichia coli, purified and tested for binding to viral RNA by a gel shift assay. The results showed that truncation of the C protein from its N-terminus by more than 10 amino acids abolished almost completely its expression in E. coli. The latter could be restored by adding a tag to the N-terminus of the protein. The tagged proteins truncated by 15 or more amino acids showed an anomalous migration in SDS-PAGE. Truncation by more than 20 amino acids resulted in a complete loss of ability of tagged C protein to bind to viral RNA. These results provide clues to the early events in the C protein - RNA interactions leading to C protein oligomerization, RNA encapsidation and virion assembly.

Human immunodeficiency virus type 1 subtype C Gag virus-like particle boost substantially improves the immune response to a subtype C gag DNA vaccine in mice

Human immunodeficiency virus type 1 (HIV-1) subtype C is the predominant HIV in southern Africa, and is the target of a number of recent vaccine candidates. It has been proposed that a heterologous prime/boost vaccination strategy may result in stronger, broader and more prolonged immune responses. Since HIV-1 Gag Pr55 polyprotein can assemble into virus-like particles (VLPs) which have been shown to induce a strong cellular immune response in animals, we showed that a typical southern African subtype C Pr55 protein expressed in insect cells via recombinant baculovirus could form VLPs. We then used the baculovirus-produced VLPs as a boost to a subtype C HIV-1 gag DNA prime vaccination in mice. This study shows that a low dose of HIV-1 subtype C Gag VLPs can significantly boost the immune response to a single subtype C gag DNA inoculation in mice. These results suggest a possible vaccination regimen for humans. © 2004 SGM.

Chimaeric HIV-1 subtype C Gag molecules with large in-frame C-terminal polypeptide fusions form virus-like particles

HIV-1 Pr55 Gag virus-like particles (VLPs) are strong immunogens with potential as candidate HIV vaccines. VLP immunogenicity can be broadened by making chimaeric Gag molecules: however, VLPs incorporating polypeptides longer than 200 aa fused in frame with Gag have not yet been reported. We constructed a range of gag-derived genes encoding in-frame C-terminal fusions of myristoylation-competent native Pr55Gag and p6-truncated Gag (Pr50Gag) to test the effects of polypeptide length and sequence on VLP formation and morphology, in an insect cell expression system. Fused sequences included a modified reverse transcriptase-Tat-Nef fusion polypeptide (RTTN, 778 aa), and truncated versions of RTTN ranging from 113 aa to 450 aa. Baculovirus-expressed chimaeric proteins were examined by western blot and electron microscopy. All chimaeras formed VLPs which could be purified by sucrose gradient centrifugation. VLP diameter increased with protein MW, from ∼100 nm for Pr55Gag to ∼250 nm for GagRTTN. The presence or absence of the Gag p6 region did not obviously affect VLP formation or appearance. GagRT chimaeric particles were successfully used in mice to boost T-cell responses to Gag and RT that were elicited by a DNA vaccine encoding a GagRTTN polypeptide, indicating the potential of such chimaeras to be used as candidate HIV vaccines. © 2008 Elsevier B.V. All rights reserved.

A prime-boost immunisation regimen using recombinant BCG and Pr55 gag virus-like particle vaccines based on HIV type 1 subtype C successfully elicits Gag-specific responses in baboons

Mycobacterium bovis BCG is considered an attractive live bacterial vaccine vector. In this study, we investigated the immune response of baboons to a primary vaccination with recombinant BCG (rBCG) constructs expressing the gag gene from a South African HIV-1 subtype C isolate, and a boost with HIV-1 subtype C Pr55 gag virus-like particles (Gag VLPs). Using an interferon enzyme-linked immunospot assay, we show that although these rBCG induced only a weak or an undetectable HIV-1 Gag-specific response on their own, they efficiently primed for a Gag VLP boost, which strengthened and broadened the immune responses. These responses were predominantly CD8+ T cell-mediated and recognised similar epitopes as those targeted by humans with early HIV-1 subtype C infection. In addition, a Gag-specific humoral response was elicited. These data support the development of HIV-1 vaccines based on rBCG and Pr55 gag VLPs. © 2009 Elsevier Ltd. All rights reserved.

HIV-1 subtype C Pr55gag virus-like particle vaccine efficiently boosts baboons primed with a matched DNA vaccine

A DNA vaccine expressing human immunodeficiency virus type 1 (HIV-1) southern African subtype C Gag (pTHGag) and a recombinant baculovirus Pr55gag virus-like particle prepared using a subtype C Pr55gag protein (Gag VLP) was tested in a prime-boost inoculation regimen in Chacma baboons. The response of five baboons to Gag peptides in a gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay after three pTHGag immunizations ranged from 100 to 515 spot-forming units (s.f.u.) per 106 peripheral blood mononuclear cells (PBMCs), whilst the response of two baboons to the Gag VLP vaccine ranged from 415 to 465 s.f.u. per 106 PBMCs. An increase in the Gag-specific response to a range of 775-3583 s.f.u. per 106 PBMCs was achieved by boosting with Gag VLPs the five baboons that were primed with pTHGag. No improvement in Gag responses was achieved in this prime-boost inoculation regimen by increasing the number of pTHGag inoculations to six. IFN-γ responses were mapped to several peptides, some of which have been reported to be targeted by PBMCs from HIV-1 subtype C-infected individuals. Gag VLPs, given as a single-modality regimen, induced a predominantly CD8+ T-cell IFN-γ response and interleukin-2 was a major cytokine within a mix of predominantly Th1 cytokines produced by a DNA-VLP prime-boost modality. The prime-boost inoculation regimen induced high serum p24 antibody titres in all baboons, which were several fold above that induced by the individual vaccines. Overall, this study demonstrated that these DNA prime/VLP boost vaccine regimens are highly immunogenic in baboons, inducing high-magnitude and broad multifunctional responses, providing support for the development of these products for clinical trials. © 2008 SGM.

An investigation into the use of human papillomavirus type 16 virus-like particles as a delivery vector system for foreign proteins: N- and C-terminal fusion of GFP to the L1 and L2 capsid proteins

Development of vaccine strategies against human papillomavirus (HPV), which causes cervical cancer, is a priority. We investigated the use of virus-like particles (VLPs) of the most prevalent type, HPV-16, as carriers of foreign proteins. Green fluorescent protein (GFP) was fused to the N or C terminus of both L1 and L2, with L2 chimeras being co-expressed with native L1. Purified chimaeric VLPs were comparable in size (∼55 nm) to native HPV VLPs. Conformation-specific monoclonal antibodies (Mabs) bound to the VLPs, thereby indicating that they possibly retain their antigenicity. In addition, all of the VLPs encapsidated DNA in the range of 6-8 kb. © 2007 Springer-Verlag.

HIV-1 sub-type C chimaeric VLPs boost cellular immune responses in mice

Several approaches have been explored to eradicate HIV; however, a multigene vaccine appears to be the best option, given their proven potential to elicit broad, effective responses in animal models. The Pr55 Gagprotein is an excellent vaccine candidate in its own right, given that it can assemble into large, enveloped, virus-like particles (VLPs) which are highly immunogenic, and can moreover be used as a scaffold for the presentation of other large non-structural HIV antigens. In this study, we evaluated the potential of two novel chimaeric HIV-1 Pr55 Gag-based VLP constructs - C-terminal fusions with reverse transcriptase and a Tat::Nef fusion protein, designated GagRT and GagTN respectively - to enhance a cellular response in mice when used as boost components in two types of heterologous prime-boost vaccine strategies. A vaccine regimen consisting of a DNA prime and chimaeric HIV-1 VLP boosts in mice induced strong, broad cellular immune responses at an optimum dose of 100 ng VLPs. The enhanced cellular responses induced by the DNA prime-VLP boost were two- to three-fold greater than two DNA vaccinations. Moreover, a mixture of GagRT and GagTN VLPs also boosted antigen-specific CD8+ and CD4+ T-cell responses, while VLP vaccinations only induced predominantly robust Gag CD4+ T-cell responses. The results demonstrate the promising potential of these chimaeric VLPs as vaccine candidates against HIV-1. © 2010 Pillay et al; licensee BioMed Central Ltd.

DRD2/ANKK1 Taq1A (rs 1800497 C>T) genotypes are associated with susceptibility to second generation antipsychotic-induced akathisia

Rationale Although the advent of atypical, second-generation antipsychotics (SGAs) has resulted in reduced likelihood of akathisia, this adverse effect remains a problem. Extrapyramidal adverse effects are associated with increased drug occupancy of dopamine 2 receptors (DRD2). The A1 allele of the DRD2/ANKK1,rs1800497, is associated with decreased striatal DRD2 density. Objectives The aim of this study was to identify whether the A1(T) allele of the DRD2/ANKK1 was associated with akathisia (measured with the Barnes Akathisia Rating Scale) in a clinical sample of 234 patients treated with antipsychotics. Results Definite akathisia (a score≥ 2 for the global clinical assessment of akathisia) was significantly less common in subjects prescribed SGAs (16.8 %) than those prescribed FGAs (47.6%), p<0.0001. Overall, 24.1% of A1+ (A1A2/A1A1) patients treated with SGAs had akathisia compared to 10.8% of A1- (A2A2) patients. A1+ (A1A2/A1A1) patients administered SGAs also had higher global clinical assessment of akathisia scores than A1- subjects (p=0.01). SGAs maintained their advantage over FGAs regarding akathisia even in A1+ patients treated with SGAs. Conclusions These results strongly suggest that A1+ variants of the DRD2/ANKK1 Taq1A allele confer risk for akathisia in patients treated with SGAs and may explain inconsistencies across prior studies comparing FGAs and SGAs.

Effect of bone morphogenetic protein-4 (BMP-4) on the expression of Sox2, Oct-4 and c-Myc in human periodontal ligament cells during long-term culture

Recent studies demonstrated endogenous expression level of Sox2, Oct-4 and c-Myc is correlated with the pluripotency and successful induction of induced pluripotent stem cells (iPSCs). Periondontal ligament cells (PDLCs)have multi-lineage diferentiation capability and ability to maintain undifferentiated stage, which makes PDLCs a suitable cell source for tissue repair and regeneration. To elucidate the effect of in vitro culture condition on the stemness potential of PDLCs, we explored the cell growth, proliferation, cell cycle, and the expression of Sox2, Oct-4 and c-Myc in PDLCs from passage 1 to 7 with or without the addition of recombinant human BMP4(rhBMP4). Our results revealed that BMP-4 promoted cell growth and proliferation, arrested PDLCs in S phase of cell cycle and upregulated PI value. It was revealed that without the addition of rhBMP4, the expression of Sox2, Oct-4 and c-Myc in PDLCs only maintained nucleus location until passage 3, then lost nucleus location subsequently. The mRNA expression in PDLCs further confirmed that the level of Sox2 and Oct-4 peaked at passage 3, then decreased afterwards, whereas c-Myc maintained consistently upregulation along passages. after the treatment with rhBMP4, the expression of Sox2, Oct-4 and c-Myc in PDLCs maintained nucleus location even at passage 7 and the mRNA expression of Sox2 and Oct-4 significantly upregulated at passage 5 and 7. These results demonstrated that addition of rhBMP-4 in the culture media could improve the current culture condition for PDLCs to maintain in an undifferentiated stage.

RcppArmadillo : accelerating R with high-performance C++ linear algebra

The R statistical environment and language has demonstrated particular strengths for interactive development of statistical algorithms, as well as data modelling and visualisation. Its current implementation has an interpreter at its core which may result in a performance penalty in comparison to directly executing user algorithms in the native machine code of the host CPU. In contrast, the C++ language has no built-in visualisation capabilities, handling of linear algebra or even basic statistical algorithms; however, user programs are converted to high-performance machine code, ahead of execution. A new method avoids possible speed penalties in R by using the Rcpp extension package in conjunction with the Armadillo C++ matrix library. In addition to the inherent performance advantages of compiled code, Armadillo provides an easy-to-use template-based meta-programming framework, allowing the automatic pooling of several linear algebra operations into one, which in turn can lead to further speedups. With the aid of Rcpp and Armadillo, conversion of linear algebra centered algorithms from R to C++ becomes straightforward. The algorithms retains the overall structure as well as readability, all while maintaining a bidirectional link with the host R environment. Empirical timing comparisons of R and C++ implementations of a Kalman filtering algorithm indicate a speedup of several orders of magnitude.

C-BN Single-Walled Nanotubes from Hybrid Connection of BN/C Nanoribbons: Prediction by ab initio Density Functional Calculations

We demonstrated for the first time by ab initio density functional calculation and molecular dynamics simulation that C0.5(BN)0.5 armchair single-walled nanotubes (NT) are gapless semiconductors and can be spontaneously formed via the hybrid connection of graphene/BN Nanoribbons (GNR/BNNR) at room temperature. The direct synthesis of armchair C0.5(BN)0.5 via the hybrid connection of GNR/BNNR is predicted to be both thermodynamically and dynamically stable. Such novel armchair C0.5(BN)0.5 NTs possess enhanced conductance as that observed in GNRs. Additionally, the zigzag C0.5(BN)0.5 SWNTs are narrow band gap semiconductors, which may have potential application for light emission. In light of recent experimental progress and the enhanced degree of control in the synthesis of GNRs and BNNR, our results highlight an interesting avenue for synthesizing a novel specific type of C0.5(BN)0.5 nanotube (gapless or narrow direct gap semiconductor), with potentially important applications in BNC-based nanodevices.