The initial step of DNA hairpin folding: a kinetic analysis using fluorescence correlation spectroscopy

Conformational fluctuations of single-stranded DNA (ssDNA) oligonucleotides were studied in aqueous solution by monitoring contact-induced fluorescence quenching of the oxazine fluorophore MR121 by intrinsic guanosine residues (dG). We applied fluorescence correlation spectroscopy as well as steady-state and time-resolved fluorescence spectroscopy to analyze kinetics of DNA hairpin folding. We first characterized the reporter system by investigating bimolecular quenching interactions between MR121 and guanosine monophosphate in aqueous solution estimating rate constants, efficiency and stability for formation of quenched complexes. We then studied the kinetics of complex formation between MR121 and dG residues site-specifically incorporated in DNA hairpins. To uncover the initial steps of DNA hairpin folding we investigated complex formation in ssDNA carrying one or two complementary base pairs (dC–dG pairs) that could hybridize to form a short stem. Our data show that incorporation of a single dC–dG pair leads to non-exponential decays for opening and closing kinetics and reduces rate constants by one to two orders of magnitude. We found positive activation enthalpies independent of the number of dC–dG pairs. These results imply that the rate limiting step of DNA hairpin folding is not determined by loop dynamics, or by mismatches in the stem, but rather by interactions between stem and loop nucleotides

Synthesis of novel MMT/acyl-protected nucleo alanine monomers for the preparation of DNA/alanyl-PNA chimeras

Alanyl-peptide nucleic acid (alanyl-PNA)/DNA chimeras are oligomers envisaged to be beneficial in efficient DNA diagnostics based on an improved molecular beacon concept. A synthesis of alanyl-PNA/DNA chimera can be based on the solid phase assembly of the oligomer with mixed oligonucleotide/peptide backbone under DNA synthesis conditions, in which the nucleotides are introduced as phosphoramidites, whereas the nucleo amino acids make use of the acid labile monomethoxytrityl (MMT) group for temporary protection of the α-amino groups and acyl protecting groups for the exocyclic amino functions of the nucleobases. In this work, we realized for the first time the synthesis of all four MMT/acyl-protected nucleo alanines, achieved by deprotection/reprotection of the newly synthesized Boc/acyl intermediates, useful monomers for the obtainment of (alanyl-PNA)/DNA chimeras by conditions fully compatible with the standard phosphoramidite DNA synthesis strategy

The future of resilient supply chains

While supply chain resilience has been touched upon frequently, research remains (with the exception of often repeated anecdotal examples) relatively disparate on what disruptions actually are. This research aims to advance theoretical and managerial understandings around the management of supply chain disruptions. A two-stage research process is used which focuses first on polling academic experts. This stage is followed by the extraction of insights from practitioners in the automotive, electronics and food industries. Our findings coalesce around: (1) the types of disruptions that respondents are most concerned about; (2) the associated strategies suggested to cope with disruptions; and, (3) how resilience can be measured. It is apparent that there are some areas where academics and practitioners agree and others where they agree to a lesser extent. Both sets of actors tend to agree on how resilience can be quantified, with recovery time the preferred indicator. However, there is a discrepancy around how resilience is achieved within the supply chain. Academics emphasise the importance of redundancy while practitioners refer more to flexibility. Also, they disagree around what constitutes “key disruptions”: academics suggested high-profile events, while practitioners are more concerned with day-to-day problems

Advances in intravesical drug delivery systems to treat bladder cancer

Chemotherapeutic agents administered intravesically to treat bladder cancer have limited efficacy due to periodic dilution and wash-out during urine formation and elimination. This review describes the pathophysiology, prevalence and staging of bladder cancer, and discusses several formulation strategies used to improve drug residence within the bladder. These include the use of amphiphilic copolymers, mucoadhesive formulations, hydrogels, floating systems, and liposomes. Various in vitro and in vivo models recently employed for intravesical drug delivery studies are discussed. Some of the challenges that have prevented the clinical use of some promising formulations are identified

Gender diversity for sustainability management: developing a research agenda from a supply chain perspective

Gender diversity (GD) is an issue that must be addressed for the sustainable development of businesses. Research is lacking on GD in the sustainability management of supply chains (SMSCs). This study addresses the potential impact of GD on SMSCs. A literature review methodology is used to review academic and professional articles over three decades. The findings show that some studies have examined GD and supply chain management (SCM) but the focus has tended to be on the challenges encountered by women in SCs, such as women as victims, but not women as potential change actors. In contrast, sustainability management literature invokes the importance of GD and the specificities women managers can bring to firms’ performance. A research agenda is proposed in this study by combining outcomes from both fields. It implies there is an important space to fill, especially concerning the environmental and social impacts GD may have on SMSCs

Nucleic acid-based fluorescent probes and their analytical potential

It is well known that nucleic acids play an essential role in living organisms because they store and transmit genetic information and use that information to direct the synthesis of proteins. However, less is known about the ability of nucleic acids to bind specific ligands and the application of oligonucleotides as molecular probes or biosensors. Oligonucleotide probes are single-stranded nucleic acid fragments that can be tailored to have high specificity and affinity for different targets including nucleic acids, proteins, small molecules, and ions. One can divide oligonucleotide-based probes into two main categories: hybridization probes that are based on the formation of complementary base-pairs, and aptamer probes that exploit selective recognition of nonnucleic acid analytes and may be compared with immunosensors. Design and construction of hybridization and aptamer probes are similar. Typically, oligonucleotide (DNA, RNA) with predefined base sequence and length is modified by covalent attachment of reporter groups (one or more fluorophores in fluorescence-based probes). The fluorescent labels act as transducers that transform biorecognition (hybridization, ligand binding) into a fluorescence signal. Fluorescent labels have several advantages, for example high sensitivity and multiple transduction approaches (fluorescence quenching or enhancement, fluorescence anisotropy, fluorescence lifetime, fluorescence resonance energy transfer (FRET), and excimer-monomer light switching). These multiple signaling options combined with the design flexibility of the recognition element (DNA, RNA, PNA, LNA) and various labeling strategies contribute to development of numerous selective and sensitive bioassays. This review covers fundamentals of the design and engineering of oligonucleotide probes, describes typical construction approaches, and discusses examples of probes used both in hybridization studies and in aptamer-based assays

The establishment of industrial branding through dyadic logistics partnership success (LPS): The case of the Malaysian automotive and logistics industry

Logistics partnerships across dyadic and triadic relationship networks have been the basis of extensive research in the extant literature. It is well understood that competitive advantage within logistics and distribution and within supply chains are driven by value-adding aspects of not only the core competencies of each tier in the network, but also via tangential supporting factors. It is also well understood that there is a strong relationship between logistics and distribution and marketing functions, particularly in product-based organisations. In addition to deepening our understanding of how successful partnerships throughout the source-make-deliver continuum can be optimised, this research also seeks to identify how a supporting element in terms of industrial branding and marketing can lead to relational sustainability. Hence, this paper outlines the relationship between logistics partnership success (LPS) factors and the inherent link to industrial branding establishment and business sustainability within the Malaysian automotive industry (specifically, car manufacturers). Adopting a multiple case study approach, findings suggest that there is a strong association between logistics service performance (LSP) provided by the third party logistics provider (TPLP) and the development and support of a mutual brand image for both the TPLP and the car manufacturer. We contribute to the extant literature on logistics partnership and industrial branding through linking LSP with the creation and maintenance of an industrial branding strategy for both parties in the context of the Malaysian automotive industry. © 2013 Elsevier Inc