Production of exopolysaccharides from a thermophilic microorganism isolated from a marine hot spring in flegrean areas

A thermophilic strain isolated from sea sand at Maronti, near Sant' Angelo (Ischia), is described. The organism grows well at an optimal temperature of 60 °C at pH 7.0. The thermophilic bacterium, named strain 4004, produces an exocellular polysaccharide (EPS) in yields of 90 mg/l. The EPS fraction was produced with all substrates tested, although a higher yield was obtained with sucrose or trehalose as sole carbon source. During growth, the EPS content was proportional to the biomass. Three fractions (EPS1, EPS2, EPS3) were obtained after purification. Quantitative monosaccharide analysis of the EPSs revealed the presence of mannose:glucose:galactose in a relative ratio of 0.5:1.0:0.3 in EPS1, mannose:glucose:galactose in a relative ratio of 1.0:0.3:trace in EPS2, and galactose:mannose:glucosamine:arabinose in a relative ratio of 1.0:0.8:0.4:0.2 in EPS3. The average molecular mass of EPS3 was determined to be 1×10⁶ Da. From comparison of the chemical shift values in ¹H and ¹³C spectra, we conclude that EPS3 presents a pentasaccharide repeating unit. Electronic Publication     

Mapping, identification of polymorphisms and analysis of allele frequencies in the porcine skeletal muscle myopalladin and titin genes

Genes coding for sarcomeric proteins may play a key role in muscle mass accretion and meat production. Screening a skeletal muscle cDNA library we isolated two partial sequences coding for the sarcomeric myopalladin and titin genes. In the present work we identified three SNPs in the 3' untranslated region, two at the myopalladin locus and one at the titin locus. Myopalladin was mapped on porcine chromosome (SSC) 14 using a somatic cell hybrid panel, a radiation hybrid panel and by linkage mapping. The linkage mapping of titin confirmed the position on SSC15. Then we analysed the allelic distribution of the alleles at both loci in six different porcine breeds. The analysis of the allele frequencies for these two loci in extremely divergent groups of pigs selected according to lean cuts (LC) and average daily gain (ADG) approached the significance level for myopalladin and LC trait. Further studies are needed to test the presence of a putative effect of myopalladin on lean meat content.     

Alveolar epithelial cell inhibition of fibroblast proliferation is regulated by MCP-1/CCR2 and mediated by PGE2

CC chemokine receptor 2 (CCR2) -/- mice are protected from experimental pulmonary fibrosis, a disease increasingly recognized as being mediated by dysfunctional interactions between epithelial cells and fibroblasts. We have sought to investigate the interactions between alveolar epithelial cells (AECs) and fibroblasts in these fibrosis-resistant (CCR2 -/-) and fibrosis-sensitive (CCR2 +/+) mice. AECs from CCR2 -/- mice suppress fibroblast proliferation more than AECs from CCR2 +/+ mice (77 vs. 43%). Exogenous administration of the CCR2 ligand monocyte chemoattractant protein-1 (MCP-1) to the fibroblast-AEC cocultures reverses the suppression mediated by CCR2 +/+ AECs but has no effect with CCR2 -/- AECs. MCP-1 regulates AEC function but not fibroblast function. AEC inhibition of fibroblast proliferation was mediated by a soluble, aspirin-sensitive factor. Accordingly, AECs from CCR2 -/- mice produce greater quantities of PGE(2) than do AECs from CCR2 +/+ mice, and MCP-1 inhibits AEC-derived PGE(2) synthesis. Diminished PGE(2) production by AECs results in enhanced fibroproliferation. Thus an important profibrotic mechanism of MCP-1/CCR2 interactions is to limit PGE(2) production in AECs after injury, thus promoting fibrogenesis.     

Exopolysaccharide production by a new Halomonas strain CRSS isolated from saline lake Cape Russell in Antarctica growing on complex and defined media

A haloalkalophilic Halomonas strain CRSS, isolated from salt sediments in Antarctica, produced exocellular polysaccharides (EPS) up to 2.9 g g(-1) dry cells. Acetate was the most efficient carbon source for EPS production. The composition of media strongly affected the nature of the polymers; a mannan and a xylo-mannan, were obtained when cells were grown on complex media. Acetate was the most efficient carbon source for EPS production and in presence of this substrate, a new polysaccharide, a fructo-glucan, was produced. The EPS fraction was composed by glucose, fructose, glucosamine and galactosamine in relative proportions of 1:0.7:0.3:trace.     

Lipid profile: a useful chemotaxonomic marker for classification of a new cyanobacterium in Spirulina genus

The morphological, physiological and genetic characteristics of an isolate cyanobacterium from hard sand of the lake Venere in the Pantelleria island (Italy) were described. The isolate with a small-size coiled helix shape, growing optimally at pH 9.2-9.5 at 30 degrees C under continuous illumination and aeration, possessed a 61.5 mol% of Guanine + Cytosine content of DNA. The lipid profile showed the presence of mono-, di-glycosyl, sulphoquinovolosyl and phosphatidyl (MGDG, DGDG, SQDG and PG). The fatty acid profile was also studied, characterized by the absence of gamma-linolenic acid and the presence of saturated and monounsaturated C16 and C18. The latter was also present as a dienoic component. The fatty acid composition was affected by growth temperature by increasing the degree of desaturation at a lower temperature and the biosynthesis of shorter acyl chains. The effects of growth conditions other than temperature, physical, nutritional and chemical on lipid composition were also studied. The overall features of the cyanobacterium isolated from Pantelleria clustered it into Spirulina genus.     

Considerations for monitoring population trends of colonial waterbirds using the effective number of breeders and census estimates

Detecting trends in population size fluctuations is a major focus in ecology, evolution, and conservation biology. Populations of colonial waterbirds have been monitored using demographic approaches to determine annual census size (N_a). We propose the addition of genetic estimates of the effective number of breeders (N_b) as indirect measures of the risk of loss of genetic diversity to improve the evaluation of demographics and increase the accuracy of trend estimates in breeding colonies. Here, we investigated which methods of the estimation of N_b are more precise under conditions of moderate genetic diversity, limited sample sizes and few microsatellite loci, as often occurs with natural populations. We used the wood stork as a model species and we offered a workflow that researchers can follow for monitoring bird breeding colonies. Our approach started with simulations using five estimators of N_b and the theoretical results were validated with empirical data collected from breeding colonies settled in the Brazilian Pantanal wetland. In parallel, we estimated census size using a corrected method based on counting active nests. Both in simulations and in natural populations, the approximate Bayesian computation (ABC) and sibship assignment (SA) methods yielded more precise estimates than the linkage disequilibrium, heterozygosity excess, and molecular coancestry methods. In particular, the ABC method performed best with few loci and small sample sizes, while the other estimators required larger sample sizes and at least 13 loci to not underestimate N_b. Moreover, according to our N_b/N_a estimates (values were often ≤0.1), the wood stork colonies evaluated could be facing the loss of genetic diversity. We demonstrate that the combination of genetic and census estimates is a useful approach for monitoring natural breeding bird populations. This methodology has been recommended for populations of rare species or with a known history of population decline to support conservation efforts.     

Tethered Domains and Flexible Regions in tRNase ZL,the Long Form of tRNase Z

tRNase Z, a member of the metallo-β-lactamase family, endonucleolytically removes the pre-tRNA 3′ trailer in a step central to tRNA maturation. The short form (tRNase Z^S) is the only one found in bacteria and archaebacteria and is also present in some eukaryotes. The homologous long form (tRNase Z^L), exclusively found in eukaryotes, consists of related amino- and carboxy-domains, suggesting that tRNase Z^L arose from a tandem duplication of tRNase Z^S followed by interdependent divergence of the domains. X-ray crystallographic structures of tRNase Z^S reveal a flexible arm (FA) extruded from the body of tRNase Z remote from the active site that binds tRNA far from the scissile bond. No tRNase Z^L structures have been solved; alternative biophysical studies are therefore needed to illuminate its functional characteristics. Structural analyses of tRNase Z^L performed by limited proteolysis, two dimensional gel electrophoresis and mass spectrometry establish stability of the amino and carboxy domains and flexibility of the FA and inter-domain tether, with implications for tRNase Z^L function.     

Prevention of Transfusion-Associated Graft-versus-Host Disease by Irradiation: Technical Aspect of a New Ferrous Sulphate Dosimetric System

Irradiation of whole blood and blood components before transfusion is currently the only accepted method to prevent Transfusion-Associated Graft-Versus-Host-Disease (TA-GVHD). However, choosing the appropriate technique to determine the dosimetric parameters associated with blood irradiation remains an issue. We propose a dosimetric system based on the standard Fricke Xylenol Gel (FXG) dosimeter and an appropriate phantom. The modified dosimeter was previously calibrated using a ⁶⁰Co teletherapy unit and its validation was accomplished with a ¹³⁷Cs blood irradiator. An ionization chamber, standard FXG, radiochromic film and thermoluminescent dosimeters (TLDs) were used as reference dosimeters to determine the dose response and dose rate of the ⁶⁰Co unit. The dose distributions in a blood irradiator were determined with the modified FXG, the radiochromic film, and measurements by TLD dosimeters. A linear response for absorbed doses up to 54 Gy was obtained with our system. Additionally, the dose rate uncertainties carried out with gel dosimetry were lower than 5% and differences lower than 4% were noted when the absorbed dose responses were compared with ionization chamber, film and TLDs.     

Can Male Circumcision Have an Impact on the HIV Epidemic in Men Who Have Sex with Men?

Background

Three trials have demonstrated the prophylactic effect of male circumcision (MC) for HIV acquisition among heterosexuals, and MC interventions are underway throughout sub-Saharan Africa. Similar efforts for men who have sex with men (MSM) are stymied by the potential for circumcised MSM to acquire HIV easily through receptive sex and transmit easily through insertive sex. Existing work suggests that MC for MSM should reach its maximum potential in settings where sexual role segregation is historically high and relatively stable across the lifecourse; HIV incidence among MSM is high; reported willingness for prophylactic circumcision is high; and pre-existing circumcision rates are low. We aim to identify the likely public health impact that MC interventions among MSM would have in one setting that fulfills these conditions—Peru—as a theoretical upper bound for their effectiveness among MSM generally.

Methods and Findings

We use a dynamic, stochastic sexual network model based in exponential-family random graph modeling and parameterized from multiple behavioral surveys of Peruvian MSM. We consider three enrollment criteria (insertive during 100%, >80% or >60% of UAI) and two levels of uptake (25% and 50% of eligible men); we explore sexual role proportions from two studies and different frequencies of switching among role categories. Each scenario is simulated 10 times. We estimate that efficiency could reach one case averted per 6 circumcisions. However, the population-level impact of an optimistic MSM-MC intervention in this setting would likely be at most ∼5–10% incidence and prevalence reductions over 25 years.

Conclusions

Roll-out of MC for MSM in Peru would not result in a substantial reduction in new HIV infections, despite characteristics in this population that could maximize such effects. Additional studies are needed to confirm these results for other MSM populations, and providers may consider the individual health benefits of offering MC to their MSM patients.     

Lactate Storm Marks Cerebral Metabolism following Brain Trauma

Brain metabolism is thought to be maintained by neuronal-glial metabolic coupling. Glia take up glutamate from the synaptic cleft for conversion into glutamine, triggering glial glycolysis and lactate production. This lactate is shuttled into neurons and further metabolized. The origin and role of lactate in severe traumatic brain injury (TBI) remains controversial. Using a modified weight drop model of severe TBI and magnetic resonance (MR) spectroscopy with infusion of ¹³C-labeled glucose, lactate, and acetate, the present study investigated the possibility that neuronal-glial metabolism is uncoupled following severe TBI. Histopathology of the model showed severe brain injury with subarachnoid and hemorrhage together with glial cell activation and positive staining for Tau at 90 min post-trauma. High resolution MR spectroscopy of brain metabolites revealed significant labeling of lactate at C-3 and C-2 irrespective of the infused substrates. Increased ¹³C-labeled lactate in all study groups in the absence of ischemia implied activated astrocytic glycolysis and production of lactate with failure of neuronal uptake (i.e. a loss of glial sensing for glutamate). The early increase in extracellular lactate in severe TBI with the injured neurons rendered unable to pick it up probably contributes to a rapid progression toward irreversible injury and pan-necrosis. Hence, a method to detect and scavenge the excess extracellular lactate on site or early following severe TBI may be a potential primary therapeutic measure.