Chemical Composition and Biological Activity of Centaurea baseri: New Species from Turkey

The genus Centaurea L. is one of the largest and important genera of Asteraceae family. Centaurea species have been widely used as herbal remedies in folk medicine for their antidandruff, antidiarrheic, antirheumatic, anti‐inflammatory, choleretic, diuretic, digestive, stomachic, astringent, antipyretic, cytotoxic, and antibacterial properties. Centaurea baseri Kose & Alan is a recently described local endemic species in Turkey and this is the first study on the chemical composition and bioactivity of its hydrodistilled essential oil and the crude extract. According to chromatospectral analysis, hexadecanoic acid (42.3%), nonacosane (8.2%), and heptacosane (8.0%) were the main compounds of the essential oil, while 16 compounds were determined in the MeOH extract using LC/MS. Furthermore, antimicrobial, antioxidant, and cytotoxic effects of the essential oil and the extract were evaluated in comparison with the standard agents. The extract showed strong antifungal effect against Candida utilis at the concentration of 60 μg/ml (MIC) where the EO showed growth inhibition at the concentration of 47.00 μg/ml (MIC) against pathogen Bacillus cereus. Both the essential oil and the extract did not show any selective antioxidant properties. The extract showed remarkably selective cytotoxic properties against MCF‐7, PANC‐1, A549, and C6 glioma cells.     

Growth and nutrient dynamics of beech (Fagus sylvatica L.) seedlings in acid soils

The relative uptake rates of N, P, K, S, Ca, Mg, Fe, Mn, Zn, Cu, and Al were estimated in beech seedlings pot cultured in the field in six acid soils (treatments). The relative uptake rates were compared with the relative growth rates. The relative uptake rates of N, K and Ca agreed well with the growth rates of the seedlings irrespective of widely differing soil conditions (acid sand-clayey till, pH 4–6). The relative uptake rates of P, Fe, and Al differed from that predicted by the growth rate. The uptake rates of Fe and Al were highest at the lowest growth rates, and the P uptake rate was lower than the growth rate in these treatments. Thus the P availability probably limited growth in an eluvial (E) horizon of a podzol, and possibly in the illuvial (B) horizon of a podzol and in an acid clayey till (Dystric Cambisol). Low P uptake was associated with a tendency towards higher relative root growth rates. In terms of the concept of steady state nutrition the high relative root growth rate in some treatments may be interpreted as an acclimation to low P supply. The P limitation seemed to be related to interactions among Fe, Al and organic compounds of the soil solution.FAX no: +4646104423     

Two recurrent nonsense mutations and a 4 bp deletion in a quasi-symmetric element in exon 37 of the NF1 gene

We screened a total of 92 unrelated patients with neurofibromatosis type 1 (NF1) for mutations in exon 37 of the NF1 gene, by using temperature gradient gel electrophoresis. Two novel mutations were found: a 4 bp deletion in a so-called quasi-symmetric element (6789delTTAC) and a recurrent nonsense mutation, which was identified in two unrelated patients, at codon 2264 (C6792A). The independent origin of the latter mutation in two families was confirmed by haplotype analysis. The nonsense mutation and the 4 bp deletion are both predicted to lead to a truncated protein product lacking the Cterminal 20% (aproximately) of its sequence. The occurrence of three independent mutations among 92 NF1 patients at codons 2263–2264 (exon 37) suggests that a specific search for mutations in this area should be undertaken in screening programs for NF1 mutations.     

Forager age and foraging state,but not cumulative foraging activity,affect biogenic amine receptor gene expression in the honeybee mushroom bodies

Foraging behavior is crucial for the development of a honeybee colony. Biogenic amines are key mediators of learning and the transition from in-hive tasks to foraging. Foragers vary considerably in their behavior, but whether and how this behavioral diversity depends on biogenic amines is not yet well understood. For example, forager age, cumulative foraging activity or foraging state may all be linked to biogenic amine signaling. Furthermore, expression levels may fluctuate depending on daytime. We tested if these intrinsic and extrinsic factors are linked to biogenic amine signaling by quantifying the expression of octopamine, dopamine and tyramine receptor genes in the mushroom bodies, important tissues for learning and memory. We found that older foragers had a significantly higher expression of Amdop1, Amdop2, AmoctαR1, and AmoctβR1 compared to younger foragers, whereas Amtar1 showed the opposite pattern. Surprisingly, our measures of cumulative foraging activity were not related to the expression of the same receptor genes in the mushroom bodies. Furthermore, we trained foragers to collect sucrose solution at a specific time of day and tested if the foraging state of time-trained foragers affected receptor gene expression. Bees engaged in foraging had a higher expression of Amdop1 and AmoctβR3/4 than inactive foragers. Finally, the expression of Amdop1, Amdop3, AmoctαR1, and Amtar1 also varied with daytime. Our results show that receptor gene expression in forager mushroom bodies is complex and depends on both intrinsic and extrinsic factors.     

Growth-enhanced salmon modify stream ecosystem functioning

Use of fast-growing domesticated and/or genetically modified strains of fish is becoming increasingly common in aquaculture, increasing the likelihood of deliberate or accidental introductions into the wild. To date, their ecological impacts on ecosystems remain to be quantified. Here, using a controlled phenotype manipulation by implanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found that growth-enhanced fish display changes in several phenotypic traits known to be important for ecosystem functioning, such as habitat use, morphology and excretion rate. Furthermore, these phenotypic changes were associated with significant impacts on the invertebrate community and key stream ecosystem functions such as primary production and leaf-litter decomposition. These findings provide novel evidence that introductions of growth-enhanced fish into the wild can affect the functioning of natural ecosystems and represent a form of intraspecific invasion. Consequently, environmental impact assessments of growth-enhanced organisms need to explicitly consider ecosystem-level effects.     

An integrated fluid–structure interaction and thrombosis model for type B aortic dissection

False lumen thrombosis (FLT) in type B aortic dissection has been associated with the progression of dissection and treatment outcome. Existing computational models mostly assume rigid wall behavior which ignores the effect of flap motion on flow and thrombus formation within the FL. In this study, we have combined a fully coupled fluid–structure interaction (FSI) approach with a shear-driven thrombosis model described by a series of convection–diffusion reaction equations. The integrated FSI-thrombosis model has been applied to an idealized dissection geometry to investigate the interaction between vessel wall motion and growing thrombus. Our simulation results show that wall compliance and flap motion can influence the progression of FLT. The main difference between the rigid and FSI models is the continuous development of vortices near the tears caused by drastic flap motion up to 4.45 mm. Flap-induced high shear stress and shear rates around tears help to transport activated platelets further to the neighboring region, thus speeding up thrombus formation during the accelerated phase in the FSI models. Reducing flap mobility by increasing the Young’s modulus of the flap slows down the thrombus growth. Compared to the rigid model, the predicted thrombus volume is 25% larger using the FSI-thrombosis model with a relatively mobile flap. Furthermore, our FSI-thrombosis model can capture the gradual effect of thrombus growth on the flow field, leading to flow obstruction in the FL, increased blood viscosity and reduced flap motion. This model is a step closer toward simulating realistic thrombus growth in aortic dissection, by taking into account the effect of intimal flap and vessel wall motion.

     

Temperature responses of photosynthetic capacity parameters were not affected by foliar nitrogen content in mature Pinus sylvestris

A key weakness in current Earth System Models is the representation of thermal acclimation of photosynthesis in response to changes in growth temperatures. Previous studies in boreal and temperate ecosystems have shown leaf‐scale photosynthetic capacity parameters, the maximum rates of carboxylation (V_cmax) and electron transport (J_max), to be positively correlated with foliar nitrogen (N) content at a given reference temperature. It is also known that V_cmax and J_max exhibit temperature optima that are affected by various environmental factors and, further, that N partitioning among the foliar photosynthetic pools is affected by N availability. However, despite the strong recent anthropogenic influence on atmospheric temperatures and N deposition to forests, little is known about the role of foliar N contents in controlling the photosynthetic temperature responses. In this study, we investigated the temperature dependencies of V_cmax and J_max in 1‐year‐old needles of mature boreal Pinus sylvestris (Scots pine) trees growing under low and high N availabilities in northern Sweden. We found that needle N status did not significantly affect the temperature responses of V_cmax or J_max when the responses were fitted to a peaked function. If such N insensitivity is a common tree trait it will simplify the interpretation of the results from gradient and multi‐species studies, which commonly use sites with differing N availabilities, on temperature acclimation of photosynthetic capacity. Moreover, it will simplify modeling efforts aimed at understanding future carbon uptake by precluding the need to adjust the shape of the temperature response curves to variation in N availability.     

Whole genome sequencing of a natural recombinant Toxoplasma gondii strain reveals chromosome sorting and local allelic variants

Background  

Toxoplasma gondii is a zoonotic parasite of global importance. In common with many protozoan parasites it has the capacity for sexual recombination, but current evidence suggests this is rarely employed. The global population structure is dominated by a small number of clonal genotypes, which exhibit biallelic variation and limited intralineage divergence. Little is known of the genotypes present in Africa despite the importance of AIDS-associated toxoplasmosis.