Aerodynamically assisted jetting and threading for processing concentrated suspensions containing advanced structural,functional and biological materials

In recent years material sciences have been interpreted right across the physical and the life sciences. Essentially this discipline broadly addresses the materials, processing, and/or fabrication right up to the structure. The materials and structures areas can range from the micro- to the nanometre scale and, in a materials sense, span from the structural, functional to the most complex, namely biological (living cells). It is generally recognised that the processing or fabrication is fundamental in bridging the materials with their structures. In a global perspective, processing has not only contributed to the materials sciences but its very nature has bridged the physical with the life sciences. In this review we discuss one such swiftly emerging fabrication approach having a plethora of applications spanning the physical and life sciences.     

One-step purification and immobilization of thermophilic polyphosphate glucokinase from <Emphasis Type="BoldItalic">Thermobifida fusca</Emphasis> YX: glucose-6-phosphate generation without ATP

The discovery of stable and active polyphosphate glucokinase (PPGK, EC 2.7.1.63) would be vital to cascade enzyme biocatalysis that does not require a costly ATP input. An open reading frame Tfu_1811 from Thermobifida fusca YX encoding a putative PPGK was cloned and the recombinant protein fused with a family 3 cellulose-binding module (CBM-PPGK) was overexpressed in Escherichia coli. Mg²⁺ was an indispensible activator. This enzyme exhibited the highest activity in the presence of 4 mM Mg²⁺ at 55°C and pH 9.0. Under its suboptimal conditions (pH 7.5), the k _cat and K _m values of CBM-PPGK on glucose were 96.9 and 39.7 s⁻¹ as well as 0.77 and 0.45 mM at 37°C and 50°C respectively. The thermoinactivation of CBM-PPGK was independent of its mass concentration. Through one-step enzyme purification and immobilization on a high-capacity regenerated amorphous cellulose, immobilized CBM-PPGK had an approximately eightfold half lifetime enhancement (i.e., t _1/2 = 120 min) as compared to free enzyme at 50°C. To our limited knowledge, this enzyme was the first thermostable PPGK reported. Free PPGK and immobilized CBM-PPGK had total turnover number values of 126,000 and 961,000 mol product per mol enzyme, respectively, suggesting their great potential in glucose-6-phosphate generation based on low-cost polyphosphate.     

High incorporation of L-amino acids to cereulide, an emetic toxin from Bacillus cereus

Cereulide is a principal toxin causing emetic syndrome produced by Bacillus cereus. This paper deals with biosynthetic studies on this unusual cyclic depsipeptide toxin from 13C labeled L-amino acid precursors (Val, Leu, Ala) upon cultivation in synthetic media. The analyses were made at atomic level of the constituent amino- or oxy-acids through NMR and ESI-MS/MS spectroscopic methods on cereulide and its hydrolysate dipeptides. The incorporation of the 13C atom was 95% in each O-Val, O-Leu and L-Val, while 40% in D-Ala of cereulide.     

Correlation between Possession of a Respiration-Dependent Na+ Pump and Na+ Requirement for Growth of Marine Bacteria

The possession of a respiration-dependent primary sodium pump and the requirement of Na⁺ for growth were investigated in bacterial isolates from marine environments. The bacteria in which NADH oxidase specifically required Na⁺ for maximum activity were believed to possess a primary sodium pump. All bacteria that failed to grow without the addition of NaCl possessed a primary Na⁺ pump. All bacteria that had no primary Na⁺ pump grew without additional NaCl. The primary Na⁺ pump seems to be involved in the Na⁺ requirement of marine bacteria, and this can be regarded as a criterion for the definition of marine bacteria.     

Induction of apoptosis by X-linked ectodermal dysplasia receptor via a caspase 8-dependent mechanism

X-linked ectodermal dysplasia receptor (XEDAR) is a recently isolated member of the tumor necrosis factor receptor family that is highly expressed during embryonic development and binds to ectodysplasin-A2 (EDA-A2). In this report, we demonstrate that although XEDAR lacks a death domain, it nevertheless induces apoptosis in an EDA-A2-dependent fashion. The apoptosis-inducing ability of XEDAR is dependent on the activation of caspase 8 and can be blocked by its genetic and pharmacological inhibitors. Although XEDAR-induced apoptosis can be blocked by dominant-negative Fas-associated death domain (FADD) protein and FADD small interfering RNA, XEDAR does not directly bind to FADD, tumor necrosis factor receptor-associated death domain (TRADD) protein, or RIP1. Instead, XEDAR signaling leads to the formation of a secondary complex containing FADD, caspase 8, and caspase 10, which results in caspase activation. Thus, XEDAR belongs to a novel class of death receptors that lack a discernible death domain but are capable of activating apoptosis in a caspase 8- and FADD-dependent fashion. XEDAR may represent an early stage in the evolution of death receptors prior to the emergence of the death domain and may play a role in the induction of apoptosis during embryonic development and adult life.     

Bio-electrosprays: the next generation of electrified jets

Biological electrosprays are rapidly becoming a robust means by which to engineer living organisms for applications ranging from tissue repair to developmental biology. We previously reported the ability to electrospray living organisms without compromising their viability, but found it challenging to achieve stability in the jetting of these organisms as a result of the chemical properties of the living cellular suspensions. Jet stability is required for the generation of a near-mono distribution of droplets, which is necessary for the development of electrospray technology as a "drop and place" biotechnique. Recently, we determined the conditions needed to achieve jet stability and were able to generate droplets with a near-mono distribution (<50 microm). In this communication, we elucidate the relationship between jet behaviour and droplet size under stable jetting conditions, with a view to further reducing the droplet size to deposit a single living cell within a droplet. We believe that this level of resolution will make electrospray jetting superior amongst the jet-based biotechnologies presently being developed for the engineering of biological architectures comprised of living cells.     

Gene expression studies on bio-electrosprayed primary cardiac myocytes

Cardiovascular pathology accounts for the greatest number of mortalities in the western world and thus the development of ex vivo cardiac tissue has vast potential in cardiac therapy. Bio-electrosprays (BES), a recently discovered direct cell engineering protocol, has demonstrated tremendous applicability for regenerative and therapeutic medicine. For bio-electrospraying to be carried forward as a novel method of cardiac tissue engineering, it is important that the process does not adversely affect cellular physiology. Our previous work has shown that bio-electrospraying does not induce cell death, activate intracellular stress pathways or induce DNA damage in primary cardiac myocytes. Here we show for the first time using genome-wide microarray analysis, that bio-electrospraying has no negative effects on global gene expression in cardiac myocytes. Moreover, we show that bio-electrospraying does not lead to endothelial cell activation. These data suggest that BES has minimal effect upon the physiology of cardiac myocytes and endothelial cells and thus paves the way for the development of BES in cardiac tissue engineering.     

The 712A/G polymorphism of Brain-derived neurotrophic factor is associated with Parkinson's disease but not Major Depressive Disorder in a Chinese Han population

Background: Overlaps in clinical, pathological and molecular characteristics of Parkinson’s disease (PD) and Major Depressive Disorder (MD-D) have promoted association studies in search of common genetic risk factors that may predispose or modify this spectrum of disorders. Experimental and clinical data suggest that genetic variations in Brain-derived neurotrophic factor (BDNF) gene may increase the risk for PD and MD-D. Methods: Two hundred and sixty-six PD, 83 MD-D and 400 controls were recruited for this study, assessed using a battery of neuropsychological tests, and genotyped for 11757C/G, 712A/G, 196A/G, and 270C/T in BDNF gene. Results: 712A/G was associated with 2.50-fold time risk of PD. By combining genotypes AG/AA with 712 GG genotype as reference (OR = 1) in stratification analysis, AG/AA genotypes were associated with PD (OR = 2.94, 95% CI = 1.88–4.61). Accordingly, the A allele was significantly overrepresented in PD compared with the G allele (OR = 3.16, 95% CI = 2.08–4.81). This distribution in females and males were similar. Conclusion: Our results suggested a novel association between BDNF 712A/G AG/AA genotypes and PD in a Chinese Han population.