A new genetic disorder in mitochondrial fatty acid beta-oxidation: ACAD9 deficiency

The acyl-CoA dehydrogenases are a family of multimeric flavoenzymes that catalyze the alpha,beta -dehydrogenation of acyl-CoA esters in fatty acid beta -oxidation and amino acid catabolism. Genetic defects have been identified in most of the acyl-CoA dehydrogenases in humans. Acyl-CoA dehydrogenase 9 (ACAD9) is a recently identified acyl-CoA dehydrogenase that demonstrates maximum activity with unsaturated long-chain acyl-CoAs. We now report three cases of ACAD9 deficiency. Patient 1 was a 14-year-old, previously healthy boy who died of a Reye-like episode and cerebellar stroke triggered by a mild viral illness and ingestion of aspirin. Patient 2 was a 10-year-old girl who first presented at age 4 mo with recurrent episodes of acute liver dysfunction and hypoglycemia, with otherwise minor illnesses. Patient 3 was a 4.5-year-old girl who died of cardiomyopathy and whose sibling also died of cardiomyopathy at age 21 mo. Mild chronic neurologic dysfunction was reported in all three patients. Defects in ACAD9 mRNA were identified in the first two patients, and all patients manifested marked defects in ACAD9 protein. Despite a significant overlap of substrate specificity, it appears that ACAD9 and very-long-chain acyl-CoA dehydrogenase are unable to compensate for each other in patients with either deficiency. Studies of the tissue distribution and gene regulation of ACAD9 and very-long-chain acyl-CoA dehydrogenase identify the presence of two independently regulated functional pathways for long-chain fat metabolism, indicating that these two enzymes are likely to be involved in different physiological functions.     

Isolation of a singly oxo-bridged Fe(III) dinuclear complex: Synthesis, crystal structure, spectroscopic and magnetic studies

The μ-oxo dinuclear complex {Fe₂O(tptz)₂[N(CN)₂]₂(NO₃)₂} (1) (where tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) has been synthesised and characterised by elemental analysis, FT-IR, UV-vis, cyclic voltammetry, Mössbauer spectroscopy, and variable-temperature magnetic susceptibility measurements and single crystal X-ray diffraction. The iron centres have a pentagonal-bipyramidal geometry. The dimeric neutral complex exhibits typical Fe-μ-O bond lengths of 1.763(1) Å and a bridge angle of 180.00°. The Fe?Fe separation is 3.526(3) Å. The Mössbauer spectrum at room temperature consists of one quadrupole doublet with an isomer shift of 0.41 mm/s and a quadrupole splitting of 1.12 mm/s. Variable-temperature magnetic susceptibility measurements have been measured in the temperature range 300-2 K, revealing an intramolecular antiferromagnetic coupling (J = −211.6 cm⁻¹).     

A family of amphiphilic dioxidovanadium(V) hydrazone complexes as potent carbonic anhydrase inhibitors along with anti-diabetic and cytotoxic activities

BioMetals - A family of dioxidovanadium(V) complexes (1–4) of the type [Na(H2O)x]+[VVO2(HL1?4)]? (x?=?4, 4.5 and 7) where HL2? represents the dianionic form of...     

Chemical and biological characterisation of a sensor surface for bioprocess monitoring

This paper describes the step-wise fabrication and characterisation of a multi-layer dual polarization interferometry (DPI) based biosensor utilising Protein G (ProG) as the bio-recognition layer for the detection of a fragment antibody (Fab'). The biosensor is capable of monitoring the concentration of Fab' product within the extracellular medium of a fed-batch fermentation after leakage from Escherichia coli (E.coli). The activity, stability and functionality of each sensor layer were analysed in situ using DPI, whilst the chemical identity and homogeneity of the chemical layers were assessed ex situ using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Two different biotin linkers were found to produce hugely differing surfaces after the capture of NeutrAvidin? (NA) and biotinylated Protein G (b-ProG). The hydrophilic (PEG)(4)-biotin linker resulted in a surface where the b-ProG layer was deposited and organised above the NA layer producing an active and stable surface, whilst the hydrophobic LC-biotin linker generated a surface where the b-ProG layer was buried within the NA layer leading to variable surfaces and poor binding of the Fab' target. The biosensor has a detection limit of 1.7 μg/ml with a dynamic range covering two orders of magnitude. The sensor can detect the onset of Fab' leakage as early as 2h following product induction, with high signal-to-noise ratios and little interference from extracellular components. Leakage of Fab' followed a biphasic profile, switching to a more rapid rate 20 h after induction, indicating accelerated product loss and the need for cultivation harvest.     

Genome-wide analysis of genetic alterations in testicular primary seminoma using high resolution single nucleotide polymorphism arrays

Testicular germ cell tumors (TGCT) represent the most common malignancy among young males. To our knowledge no comprehensive Copy Number Variation (CNVs) studies of TGCT using high-resolution Single Nucleotide Polymorphism (SNP) array have been performed. By a genome-wide analysis of CNV and loss of heterozygosity (LOH) in 25 primary seminomas, we confirmed several previously reported genomic alterations and discovered eight novel genomic alterations including amplifications and homozygous deletions. Moreover, a comparison of genomic alterations of early and late stage seminoma identified CNVs that correlate with progression, which included deletions in chromosomes 4q, 5p, 9q, 13q and 20p and amplifications in chromosomes 9q and 13q. We compared previously perform Affymetrix expression analysis in a subset of samples and found robust correlation between expression and genomic alterations. Furthermore, high correlations (40-75%) were observed between CNV by SNP analysis and quantitative PCR. Our findings may lead to better understanding of TGTC's pathogenesis.     

Study of elastic collisions of Myxococcus xanthus in swarms

In very low density situations where a single myxobacterial cell is isolated from direct contact with other cells, the slime capsule interaction with the substrate or slime tracks on the substrate produce a viscous drag that results in a smooth gliding motion. Viscoelastic interactions of myxobacteria cells in a low-density domain close to the edge of a swarm are studied using a combination of a cell-based three-dimensional computational model and cell-tracking experiments. The model takes into account the flexible nature of Myxococcus xanthus as well as the effects of adhesion between cells arising from the interaction of the capsular polysaccharide covering two cells in contact with each other. New image and dynamic cell curvature analysis algorithms are used to track and measure the change in cell shapes that occur as flexible cells undergo significant bending during collisions resulting in direct calibration of the model parameters. Like aspect-ratio and directional reversals, the flexibility of cells and the adhesive cell-cell and cell-substrate interactions of M. xanthus play an important role in smooth gliding and more efficient swarming.     

Characterization of hibernating ribosomes in mammalian cells

Protein synthesis across kingdoms involves the assembly of 70S (prokaryotes) or 80S (eukaryotes) ribosomes on the mRNAs to be translated. 70S ribosomes are protected from degradation in bacteria during stationary growth or stress conditions by forming dimers that migrate in polysome profiles as 100S complexes. Formation of ribosome dimers in Escherichia coli is mediated by proteins, namely the ribosome modulation factor (RMF), which is induced in the stationary phase of cell growth. It is reported here a similar ribosomal complex of 110S in eukaryotic cells, which forms during nutrient starvation. The dynamic nature of the 110S ribosomal complex (mammalian equivalent of the bacterial 100S) was supported by the rapid conversion into polysomes upon nutrient-refeeding via a mechanism sensitive to inhibitors of translation initiation. Several experiments were used to show that the 110S complex is a dimer of nontranslating ribosomes. Cryo-electron microscopy visualization of the 110S complex revealed that two 80S ribosomes are connected by a flexible, albeit localized, interaction. We conclude that, similarly to bacteria, rat cells contain stress-induced ribosomal dimers. The identification of ribosomal dimers in rat cells will bring new insights in our thinking of the ribosome structure and its function during the cellular response to stress conditions.Key words: ribosome, translation, stress, starvation, polysome