The RIN2 syndrome: a new autosomal recessive connective tissue disorder caused by deficiency of Ras and Rab interactor 2 (RIN2)

Defects leading to impaired intracellular trafficking have recently been shown to play an important role in the pathogenesis of genodermatoses, such as the Ehlers–Danlos and the cutis laxa syndromes. A new genodermatosis, termed macrocephaly, alopecia, cutis laxa and scoliosis (MACS) syndrome has been described, resulting from a homozygous 1-bp deletion in RIN2. RIN2 encodes the Ras and Rab interactor 2, involved in the regulation of Rab5-mediated early endocytosis. We performed a clinical, ultrastructural and molecular study in a consanguineous Algerian family with three siblings affected by a distinctive autosomal recessive genodermatosis, reported in 2005 by Verloes et al. The most striking clinical features include progressive facial coarsening, gingival hypertrophy, severe scoliosis, sparse hair and skin and joint hyperlaxity. Ultrastructural studies of the skin revealed important abnormalities in the collagen fibril morphology, and fibroblasts exhibited a dilated endoplasmic reticulum and an abnormal Golgi apparatus with rarefied and dilated cisternae. Molecular analysis of RIN2 revealed a novel homozygous 2-bp deletion in all affected individuals. The c.1914_1915delGC mutation introduces a frameshift and creates a premature termination codon, leading to nonsense-mediated mRNA decay. These findings confirm that RIN2 defects are associated with a distinct genodermatosis and underscore the involvement of RIN2 and its associated pathways in the pathogenesis of connective tissue disorders. The current family displays considerable phenotypic overlap with MACS syndrome. However, our family shows a dermatological and ultrastructural phenotype belonging to the Ehlers–Danlos rather than the cutis laxa spectrum. Therefore, the MACS acronym is not entirely appropriate for the current family.     

Changes with time in the H+ concentration of the culture medium influences morphogenesis in tobacco thin cell layers

Different types of morphogenesis in thin cell layers of Nicotiana tabacum cv. Samsun were studied in relation to changes in the external H⁺ concentration during cluture. Different initial pHs of the medium, ranging from 3.83 to 6.35, were tested under unbuffered and MES-buffered conditions, in combination with various amounts of indolyl-3-butyric acid and kinetin. The explants were sequentially transferred from MES-free media to MES-supplemented media, as well as reciprocally, to determine possible periods during the morphogenic process that showed a particular sensitivity to the external pH. Starting from pH 3.83, 36 m M MES induced the formation of limited callus and of vegetative and floral shoots as flowers in the control. MES at 50 m M inhibited rhizogenesis and either prevented morphogenesis or induced vegetative buds or flowers, depending on the initial pH. The 4th day of culture was a determining period in the induction of roots and flowers. Rhizogenesis, but not floral or vegetative organogenesis, was related to the theoretical intracellular concentration of indolyl-3-butyric acid. H⁺ transport might be involved in the regulation of morphogenesis.     

The elixir phase of chain molecules

A phase of matter is a familiar notion for inanimate physical matter. The nature of a phase of matter transcends the microscopic material properties. For example, materials in the liquid phase have certain common properties independent of the chemistry of the constituents: liquids take the shape of the container; they flow; and they can be poured—alcohol, oil, and water as well as a Lennard-Jones computer model exhibit similar behavior when poised in the liquid phase. Here, we identify a hitherto unstudied “phase” of matter, the elixir phase, in a simple model of a polymeric chain whose backbone has the correct local cylindrical symmetry induced by the tangent to the chain. The elixir phase appears on breaking the cylindrical symmetry by adding side spheres along the negative normal direction, as in proteins. This phase, nestled between other phases, has multiple ground states made up of building blocks of helices and almost planar sheets akin to protein native folds. We discuss the similarities of this “phase” of a finite size system to the liquid crystal and spin glass phases. Our findings are relevant for understanding proteins; the creation of novel bioinspired nanomachines; and also may have implications for life elsewhere in the cosmos.     

Synthesis and characterization of pyridoxine,nicotine and nicotinamide salts of dithiophosphoric acids as antibacterial agents against resistant wound infection

The pyridine-derived biomolecules are of considerable interest in developing medicinal compounds with various specific activities. Novel ammonium salts of pyridoxine, (S)-(–)-nicotine and nicotinamide with O,O-diorganyl dithiophosphoric acids (DTPA) were synthesized and characterized. The complexation of chiral monoterpenyl DTPA, including (S)-(–)-menthyl, (R)-(+)-menthyl, (1R)-endo-(+)-fenchyl, (1S,2S,3S,5R)-(+)-isopinocampheolyl derivatives, with pyridoxine and nicotine provided effective antibacterial compounds 3a,b,e,f, and 5a,b,d,f with MIC values against Gram-positive bacteria as low as 10?µM (6?µg/mL). Two selected pyridoxine and nicotine salts based on menthyl DTPA 3a and 5a were similarly active against antibiotic-resistant bacteria from burn wounds including MRSA. The compounds had enhanced amphiphilic and hemolytic properties and effectively altered surface characteristics and matrix-secreting ability of P. aeroginosa and S. aureus. MBC/MIC ratios of 3a and 5a suggested the bactericidal mode of their action. Furthermore, the compounds exhibited moderate cytotoxicity towards human skin fibroblasts (IC₅₀?=?48.6 and 57.6?µM, respectively, 72?h), encouraging their further investigation as potential antimicrobials against skin and wound infections.     

Unincorporated iron pool is linked to oxidative stress and iron levels in Caenorhabditis elegans

Free radicals or reactive oxygen species (ROS) are relatively short-lived and are difficult to measure directly; so indirect methods have been explored for measuring these transient species. One technique that has been developed using Escherichia coli and Saccharomyces cerevisiae systems, relies on a connection between elevated superoxide levels and the build-up of a high-spin form of iron (Fe(III)) that is detectable by electron paramagnetic resonance (EPR) spectroscopy at g?=?4.3. This form of iron is referred to as "free" iron. EPR signals at g?=?4.3 are commonly encountered in biological samples owing to mononuclear high-spin (S?=?5/2) Fe(III) ions in sites of low symmetry. Unincorporated iron in this study refers to this high-spin Fe(III) that is captured by desferrioxamine which is detected by EPR at g value of 4.3. Previously, we published an adaptation of Fe(III) EPR methodology that was developed for Caenorhabditis elegans, a multi-cellular organism. In the current study, we have systematically characterized various factors that modulate this unincorporated iron pool. Our results demonstrate that the unincorporated iron as monitored by Fe(III) EPR at g?=?4.3 increased under conditions that were known to elevate steady-state ROS levels in vivo, including: paraquat treatment, hydrogen peroxide exposure, heat shock treatment, or exposure to higher growth temperature. Besides the exogenous inducers of oxidative stress, physiological aging, which is associated with elevated ROS and ROS-mediated macromolecular damage, also caused a build-up of this iron. In addition, increased iron availability increased the unincorporated iron pool as well as generalized oxidative stress. Overall, unincorporated iron increased under conditions of oxidative stress with no change in total iron levels. However, when total iron levels increased in vivo, an increase in both the pool of unincorporated iron and oxidative stress was observed suggesting that the status of the unincorporated iron pool is linked to oxidative stress and iron levels.     

A universal primer multiplex PCR method for typing of toxinogenic Pseudomonas aeruginosa

Pseudomonas aeruginosa is a well-known opportunistic pathogen that can cause acute nosocomial necrotizing pneumonia and genetic disorder cystic fibrosis of lung patients. Pathogenic interactions between P. aeruginosa and hosts are often guided by the secreted virulence determinants that interact with specific host targets. Exotoxin A, pyocyanin, elastase, and type III secretion system are the most significant virulence determinants and cause great concern. However, P. aeruginosa in various environments has high genotypic diversity, leading to deficiency of exotoxin genes for some P. aeruginosa strains. In current study, a universal primer-multiplex PCR method (UP-MPCR) was employed for the detection of five significant enterotoxin genes (toxA, phzM, lasB, ExoU, and ExoS) and one internal control gene ecfX in P. aeruginosa. Owing to the application of universal primer (UP), different targeted products have identical amplified efficiency and the sensitivity of multiplex PCR is improved. In addition, the complexity of multiplex PCR system is reduced and the compatibility of primers in a reaction is greatly increased. This UP-MPCR method can detect the presence of five P. aeruginosa enterotoxin genes in a single assay more rapidly and sensitively than conventional methods. In 214 drinking water and environmental isolates, the ExoU, ExoS, phzM, toxA, and lasB genes were detected in 20 (9?%), 180 (84?%), 179 (84?%), 196 (92?%), and 171 (80?%) isolates, respectively.     

Involvement of myosin Vb in glutamate receptor trafficking

Myosin V motors mediate cargo transport; however, the identity of neuronal molecules transported by these proteins remains unknown. Here we show that myosin Vb is expressed in several neuronal populations and associates with the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate-type glutamate receptor subunit GluR1. In developing hippocampal neurons, expression of the tail domain of myosin Vb, but not myosin Va, enhanced GluR1 accumulation in the soma and reduced its surface expression. These changes were accompanied by reduced GluR1 clustering and diminished frequency of excitatory but not inhibitory synaptic currents. Similar effects were observed upon expression of full-length myosin Vb lacking a C-terminal region required for binding to the small GTPase Rab11. In contrast, mutant myosin Vb did not change the localization of several other neurotransmitter receptors, including the glutamate receptor subunit NR1. These results reveal a novel mechanism for the transport of a specific glutamate receptor subunit in neurons mediated by a member of the myosin V family.