Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations

Axial spondylometaphyseal dysplasia (axial SMD) is an autosomal recessive disease characterized by dysplasia of axial skeleton and retinal dystrophy. We conducted whole exome sequencing and identified C21orf2 (chromosome 21 open reading frame 2) as a disease gene for axial SMD. C21orf2 mutations have been recently found to cause isolated retinal degeneration and Jeune syndrome. We found a total of five biallelic C21orf2 mutations in six families out of nine: three missense and two splicing mutations in patients with various ethnic backgrounds. The pathogenic effects of the splicing (splice-site and branch-point) mutations were confirmed on RNA level, which showed complex patterns of abnormal splicing. C21orf2 mutations presented with a wide range of skeletal phenotypes, including cupped and flared anterior ends of ribs, lacy ilia and metaphyseal dysplasia of proximal femora. Analysis of patients without C21orf2 mutation indicated genetic heterogeneity of axial SMD. Functional data in chondrocyte suggest C21orf2 is implicated in cartilage differentiation. C21orf2 protein was localized to the connecting cilium of the cone and rod photoreceptors, confirming its significance in retinal function. Our study indicates that axial SMD is a member of a unique group of ciliopathy affecting skeleton and retina.     

Enzymatic hydrolysis of cod (Gadus morhua) by-products: Optimization of yield and properties of lipid and protein fractions

The main products of hydrolysis of fish by-products are hydrolysed protein and oil. The aim of this work was to study the effect of initial heat inactivation of endogenous enzymes, addition of water prior to hydrolysis, use of different commercial enzymes and combination of enzymes on the yield and purity of the protein and oil fractions after enzymatic hydrolysis of cod by-products. This study was designed to examine how all these factors were effective for destroying protein–lipid complexes in order to obtain pure oil and protein fractions and reduce the insoluble fraction.

Initial heating of raw material changed both raw material properties and inactivated endogenous enzymes thereby influencing the following hydrolysis. High amount of lipids in raw material combined with initial heating caused formation of protein–lipid complexes which was found in all protein containing fractions. The main constituents of the lipids in the complexes were phospholipids and other polar lipids. Insoluble protein–lipid complexes formed lead to increased amount of sludge, reduced FPH yield and high amount of lipids in FPH. The highest amount of separated oil was obtained in the experiments after initial heating without added water. These treatments also reduce amount of emulsion, which is not a desirable product after hydrolysis. Initial heating caused denaturation of protein, which decreased their emulsifying properties.

Results showed that it is not possible to obtain all desirable quality indicators such as: maximum oil and FPH yield, minimum emulsion and sludge yield and the highest protein recovery in FPH with the lowest amount of lipids in FPH fraction by using only one hydrolysis process. Therefore, the aim and requirements for the final products should be prioritised and defined very clearly before the process is designed taking into account the composition of raw material. Hydrolysis of unheated raw material with Alcalase and addition of water was the best compromise taking into account the mentioned quality indicators.     

Nitrogen oligotrophication in northern hardwood forests

While much research over the past 30 years has focused on the deleterious effects of excess N on forests and associated aquatic ecosystems, recent declines in atmospheric N deposition and unexplained declines in N export from these ecosystems have raised new concerns about N oligotrophication, limitations of forest productivity, and the capacity for forests to respond dynamically to disturbance and environmental change. Here we show multiple data streams from long-term ecological research at the Hubbard Brook Experimental Forest in New Hampshire, USA suggesting that N oligotrophication in forest soils is driven by increased carbon flow from the atmosphere through soils that stimulates microbial immobilization of N and decreases available N for plants. Decreased available N in soils can result in increased N resorption by trees, which reduces litterfall N input to soils, further limiting available N supply and leading to further declines in soil N availability. Moreover, N oligotrophication has been likely exacerbated by changes in climate that increase the length of the growing season and decrease production of available N by mineralization during both winter and spring. These results suggest a need to re-evaluate the nature and extent of N cycling in temperate forests and assess how changing conditions will influence forest ecosystem response to multiple, dynamic stresses of global environmental change.     

Hypoxia: a window into Mycobacterium tuberculosis latency

Tuberculosis is a massive public health problem on a global scale and the success of Mycobacterium tuberculosis is linked to its ability to persist within humans for long periods without causing any overt disease symptoms. Hypoxia is predicted to be a key host-induced stress limiting growth of the pathogen in vivo . However, multiple studies in vitro and in vivo indicate that M. tuberculosis adapts to oxygen limitation by entering into a metabolically altered state, while awaiting the opportunity to reactivate. Molecular signatures of bacteria adapted to hypoxia in vitro are accumulating, although correlations to human disease are only now being established. Similarly, defining the mechanisms that control this adaptation is an active area of research. In this review we discuss the historical precedents linking hypoxia and latency, and the gathering knowledge of M. tuberculosis hypoxic responses. We also examine the role of these responses in tuberculosis latency, and identify promising avenues for future studies.     

Radiation-induced fluctuation of the polysome content in adequately oxygenated tetrahymena pyriformis.

The polysome content of the ciliate protozoan Tetrahymena pyriformis is transiently reduced by gamma-irradiation. In order to test whether this is a result of a respiration-produced or radiation-produced hypoxia or some other mechanism, the oxygen content of the culture was determined during and after irradiation, and the polysome contents and rates of amino acid incorporation were measured with and without air bubbling. Irradiation (40 krad at approximately 3 krad/min) produced approximately a 25 per cent loss in dissolved O2 content in the medium. This decrease is not sufficient to affect the polysome level, since (a) the same radiation-induced loss of polysomes and inhibiition of amino acid incorporation was observed whether or not the culture was bubbled with air during the irradiation and (b) bubbling unirradiated cultures with gas mixtures containing as little as 17 per cent of the normal O2 content did not influence the polysome level. As long as the cells are irradiated as a shallow layer in open flasks, replacement of O2 from the gas phase appears adequate, and neither respiration-induced nor radiation-induced hypoxia masks the effects of the radiation.     

The action of phospholipase C and lipase on black film bilayer membranes

Phospholipase C(C. perfringens) added to one side of a phosphatidyl choline—phosphatidyl serine—cholesterol (0.7: 0.3: 1.0, w/w/w) bilayer membrane resulted in a rapid decrease in membrane resistance which leveled off after several minutes at about one-half its initial value. Pancreatic lipase added at this time resulted in a rapid increase in membrane resistance to a value somewhat higher than the initial. This effect was independent of the side to which the lipase was added, indicating that diglyceride is rapidly equilibrated across both sides of the membrane. When both phospholipase C and lipase were added at zero time to the same or opposite sides, the resistance decreased slightly and then increased to a value higher than the initial. Replacement of phosphatidyl choline by 2-hexadecoxy-3-octadecoxypropyl-phosphonylcholine, a phosphonate analog, resulted in an inhibition of the phospholipase C reaction which was equal to the percent analog. The analog, thus, seemed to act only as inert lipid and did not inhibit hydrolys of the active lipid.     

Ultra-low Dose Aerosol Infection of Mice with Mycobacterium tuberculosis More Closely Models Human Tuberculosis

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