Variation in melanin pigmentation of a sexually selected plumage trait and its adaptive value in the Common Snipe Gallinago gallinago

There is increasing evidence that melanin‐based plumage coloration correlates with different components of fitness and that it may act as a social or sexual signal of individual quality. We analysed variation in melanin pigmentation in the outermost tail feathers of the Common Snipe Gallinago gallinago. During courtship flights, male Snipe use their outermost tail feathers to generate a drumming sound, which plays a role in territory establishment and mate choice. As the outermost tail feathers are displayed to females during these flights, we predicted that conspicuous variation in their rusty‐brown (pheomelanin‐based) coloration may act as an honest signal of individual quality. To test this prediction, we spectrophotometrically measured brightness (an indicator of total melanin content) and red chroma (an indicator of pheomelanin content) of the outermost tail feathers in 180 juvenile and adult Common Snipe. An age‐related decline in feather brightness was found exclusively in females, suggesting that melanization could have evolved by natural selection to camouflage incubating birds. In both sexes, brightness of the tail feathers was inversely correlated with their structural quality (as measured with mass–length residuals), suggesting that melanization could increase mechanical properties of feathers and, in males, enhance the quality of courtship sonation. Red chroma positively correlated with total plasma protein concentration, supporting our prediction that pheomelanin pigmentation of tail feathers may act as an honest signal of condition. Our study indicated that variation in the melanin‐based coloration of the outermost tail feathers in the Common Snipe could have evolved as a result of several different selection pressures and it emphasizes the complexity of the processes that underlie the evolution of melanin‐based plumage coloration in birds.     

Purification and properties of inosine-guanosine phosphorylase from Escherichia coli K-12.

A xanthosine-inducible enzyme, inosine-guanosine phosphorylase, has been partially purified from a strain of Escherichia coli K-12 lacking the deo-encoded purine nucleoside phosphorylase. Inosine-guanosine phosphorylase had a particle weight of 180 kilodaltons and was rapidly inactivated by p-chloromercuriphenylsulfonic acid (p-CMB). The enzyme was not protected from inactivation by inosine (Ino), 2'-deoxyinosine (dIno), hypoxanthine (Hyp), Pi, or alpha-D-ribose-1-phosphate (Rib-1-P). Incubating the inactive enzyme with dithiothreitol restored the catalytic activity. Reaction with p-CMB did not affect the particle weight. Inosine-guanosine phosphorylase was more sensitive to thermal inactivation than purine nucleoside phosphorylase. The half-life determined at 45 degrees C between pH 5 and 8 was 5 to 9 min. Phosphate (20 mM) stabilized the enzyme to thermal inactivation, while Ino (1 mM), dIno (1 mM), xanthosine (Xao) (1 mM), Rib-1-P (2 mM), or Hyp (0.05 mM) had no effect. However, Hyp at 1 mM did stabilize the enzyme. In addition, the combination of Pi (20 mM) and Hyp (0.05 mM) stabilized this enzyme to a greater extent than did Pi alone. Apparent activation energies of 11.5 kcal/mol and 7.9 kcal/mol were determined in the phosphorolytic and synthetic direction, respectively. The pH dependence of Ino cleavage or synthesis did not vary between 6 and 8. The substrate specificity, listed in decreasing order of efficiency (V/Km), was: 2'-deoxyguanosine, dIno, guanosine, Xao, Ino, 5'-dIno, and 2',3'-dideoxyinosine. Inosine-guanosine phosphorylase differed from the deo operon-encoded purine nucleoside phosphorylase in that neither adenosine, 2'-deoxyadenosine, nor hypoxanthine arabinoside were substrates or potent inhibitors. Moreover, the E. coli inosine-guanosine phosphorylase was antigenically distinct from the purine nucleoside phosphorylase since it did not react with any of 14 monoclonal antisera or a polyvalent antiserum raised against deo-encoded purine nucleoside phosphorylase.     

Increased yield and selected properties of bacterial cellulose exposed to different modes of a rotating magnetic field

Rotating magnetic field (RMF) is an interesting alternative to conventional bacterial cellulose (BC) production methods. The BC synthesis processes may be affected by RMF, which facilitates the transfer of oxygen and nutrients from the media to the microbial cells. RMF may also directly influence the various physical and chemical properties of BC. The main aim of the present study was to evaluate the impact of the RMF on the BC in regard to its yield and material properties. The correlation between the efficiency of polymer production and the different time of exposure to the RMF was also analyzed to determine the conditions of lower energy consumption during the cellulose formation process. It was found that the Gluconacetobacter xylinus cultures exposed to the RMF for a half of the time of the entire cellulose production process (72 h), considering the results obtained in controls, synthesized BC more effectively than bacteria continuously exposed to the RMF for 144 h. Furthermore, the application of the RMF, regardless of the exposure mode, did not negatively affect the polymer material properties. It was concluded that the use of the RMF may provide a novel technique for altering cellulose biogenesis and may be used in multiple biotechnological applications.     

RUNX1B Expression Is Highly Heterogeneous and Distinguishes Megakaryocytic and Erythroid Lineage Fate in Adult Mouse Hematopoiesis

The Core Binding Factor (CBF) protein RUNX1 is a master regulator of definitive hematopoiesis, crucial for hematopoietic stem cell (HSC) emergence during ontogeny. RUNX1 also plays vital roles in adult mice, in regulating the correct specification of numerous blood lineages. Akin to the other mammalian Runx genes, Runx1 has two promoters P1 (distal) and P2 (proximal) which generate distinct protein isoforms. The activities and specific relevance of these two promoters in adult hematopoiesis remain to be fully elucidated. Utilizing a dual reporter mouse model we demonstrate that the distal P1 promoter is broadly active in adult hematopoietic stem and progenitor cell (HSPC) populations. By contrast the activity of the proximal P2 promoter is more restricted and its upregulation, in both the immature Lineage^- Sca1^high cKit^high (LSK) and bipotential Pre-Megakaryocytic/Erythroid Progenitor (PreMegE) populations, coincides with a loss of erythroid (Ery) specification. Accordingly the PreMegE population can be prospectively separated into “pro-erythroid” and “pro-megakaryocyte” populations based on Runx1 P2 activity. Comparative gene expression analyses between Runx1 P2⁺ and P2^- populations indicated that levels of CD34 expression could substitute for P2 activity to distinguish these two cell populations in wild type (WT) bone marrow (BM). Prospective isolation of these two populations will enable the further investigation of molecular mechanisms involved in megakaryocytic/erythroid (Mk/Ery) cell fate decisions. Having characterized the extensive activity of P1, we utilized a P1-GFP homozygous mouse model to analyze the impact of the complete absence of Runx1 P1 expression in adult mice and observed strong defects in the T cell lineage. Finally, we investigated how the leukemic fusion protein AML1-ETO9a might influence Runx1 promoter usage. Short-term AML1-ETO9a induction in BM resulted in preferential P2 upregulation, suggesting its expression may be important to establish a pre-leukemic environment.     

Polymorphism in exon 6 of the human NT5E gene is associated with aortic valve calcification

ABSTRACT

NT5E encodes ecto-5′-nucleotidase (e5NT, CD73) which hydrolyses extracellular AMP to adenosine. Adenosine has been shown to play a protective role against aortic valve calcification (AVC). We identified two nonsynonymous missense single nucleotide polymorphisms (c.1126A > G, p.T376A and c.1136T > C, p.M379T) in exon 6 of the human NT5E gene. Since both substitutions might affect e5NT activity and consequently alter extracellular adenosine levels, we evaluated the association between NT5E alleles and calcific aortic valve disease in 119 patients (95 patients with AVC and 24 controls). In AVC patients, the frequency of the G allele at c.1126 and the frequency of the GG genotype as well as the frequency of the C allele at c.1136, and the frequencies of CC and TC genotypes tended to be higher as compared to controls. The allele and genotype frequencies in AVC patients and controls were also compared to those calculated from the 1000 Genomes Project data for control individuals of European ancestry (n = 503). We found that the frequency of the C allele at c.1136 is significantly higher in patients with AVC than in the European controls (0.111 vs. 0.054, P = 0.0052). Moreover, e5NT activity in aortic valves showed a trend toward lower levels in AVC patients with CC and TC genotypes than in those with the TT genotype. Our findings indicate that the genetic polymorphism of NT5E may contribute to the pathogenesis of calcific aortic valve disease and that the C allele of SNP c.1136 is associated with an increased risk of AVC.     

Redox conditions during sedimentation of the Middle Jurassic (Upper Bajocian–Bathonian) clays of the Polish Jura (south-central Poland)

Depositional redox conditions of the uppermost Bajocian–Bathonian (Middle Jurassic) ore-bearing clays of the Gnaszyn/Kawodrza area in the Polish Jura have been determined using an integrated geochemical (Th/U and U/Th ratios, degree of pyritisation (DOP), sulphur stable isotopes, biomarker analysis) and petrographic approach (measurements of pyrite framboid diameters, and microfacies analysis). The Th/U and U/Th ratios indicate that oxic conditions prevailed on the sea-floor during this interval, and ³⁴S isotopes suggest open-system conditions. DOP values, however, are rather scattered, and may reflect oxic, dysoxic, or anoxic conditions. We consider that the DOP values result from reducing conditions within the sediment and the chemistry of the pore-waters, rather than true sea-floor redox conditions. Pyrite framboid populations also indicate that dysoxic conditions prevailed within the sediment, beneath an oxygenated water column. Biomarker data did not provide any evidence of water column stratification or anoxia during sedimentation of the Middle Jurassic clays.     

Preservation and sterilization methods of the meniscal allografts: literature review

Nowadays, there are four types of meniscal allografts known: fresh, cryopreserved, deep-frozen and lyophilized ones but only two of them are widely used in clinical practice. Use of different types of meniscal allografts still remains controversial due to preparation method, their biomechanical properties as well as cost which is connected with processing and storage. The main aim of this review is to present the current status of knowledge concerning meniscal allograft preservation and sterilization, especially the advantages and disadvantages of each method. Authors wanted to show a broad spectrum of methods used and conceptions presented by other authors. The second aim is to gather available information about meniscal preservation and sterilization methods in one paper. Deep-frozen and cryopreserved meniscal allografts are the most frequently used ones in the clinical practice. The use of fresh grafts stays controversial but also has many followers. Lyophilized grafts in turn are not applied at present due to some serious drawbacks including reduction of tensile strength, poor rehydration, graft shrinkage and post-transplantation joint effusion as well as increased risk of meniscal size reduction. An application of sterilizing agents make the meniscal allograft free from the bacteria and viruses, but also it may cause serious structure changes. Therefore, choosing just one ideal method of meniscal allograft preservation and sterilization is complicated and should be based on broad knowledge and experience of surgeon performing the transplantation.     

A Genome-Wide Screen for Machinery Involved in Downregulation of MHC Class I by HIV-1 Nef

The HIV-1-encoded protein, Nef, plays a key role in the development of AIDS. One of Nef’s functions is to keep MHC class I off the surface of infected cells, a process that requires the host proteins clathrin and AP-1. To identify other proteins involved in this pathway, we carried out a genome-wide siRNA library screen on HeLa cells co-expressing HLA-A2 and an inducible form of Nef. Out of 21,121 siRNA pools, 100 were selected for further analysis, based on their ability to either inhibit or enhance downregulation of MHC-I by Nef. When cells were treated with the same siRNA pools as those used in the screen, 79% produced a similar phenotype. However, when the cells were treated with different siRNA reagents targeting the same genes, only 16% produced a similar phenotype. This indicates that most of the hits found in the original screen are likely to have been off-target, an important concern that is often not taken into account in siRNA screening studies. Nevertheless, we identified novel host factors involved in Nef-induced downregulation of MHC-I, including four genes, MIIP, CAMSAP3, SLC6A3, and KCTD19, where multiple reagents produced a strong inhibitory effect on Nef activity. Other hits slightly below our very high stringency cutoff point may also deserve further study. Thus, our dataset is a valuable resource for scientists investigating the pathogenesis of HIV.     

Low‐dose angiostatic tyrosine kinase inhibitors improve photodynamic therapy for cancer: lack of vascular normalization

Photodynamic therapy (PDT) is an effective clinical treatment for a number of different cancers. PDT can induce hypoxia and inflammation, pro‐angiogenic side effects, which may counteract its angio‐occlusive mechanism. The combination of PDT with anti‐angiogenic drugs offers a possibility for improved anti‐tumour outcome. We used two tumour models to test the effects of the clinically approved angiostatic tyrosine kinase inhibitors sunitinib, sorafenib and axitinib in combination with PDT, and compared these results with the effects of bevacizumab, the anti‐VEGF antibody, for the improvement of PDT. Best results were obtained from the combination of PDT and low‐dose axitinib or sorafenib. Molecular analysis by PCR revealed that PDT in combination with axitinib suppressed VEGFR‐2 expression in tumour vasculature. Treatment with bevacizumab, although effective as monotherapy, did not improve PDT outcome. In order to test for tumour vessel normalization effects, axitinib was also applied prior to PDT. The absence of improved PDT outcome in these experiments, as well as the lack of increased oxygenation in axitinib‐treated tumours, suggests that vascular normalization did not occur. The current data imply that there is a future for certain anti‐angiogenic agents to further improve the efficacy of photodynamic anti‐cancer therapy.