The biogeographic history of Phoenicurus redstarts reveals an allopatric mode of speciation and an out-of-Himalayas colonization pattern

Montane areas host high levels of diversity and endemism, and these features are tied to habitat stratification along an elevational gradient. As such, montane areas are often thought of as model systems in which sympatric speciation can occur. To test this idea, we selected Phoenicurus redstarts, an avian genus with an extensive distribution across Eurasia, as well as Northwest Africa; nine of the 14 species in the genus have distributions which include the Himalayas. We used sequences of the mtDNA ND2 and cytochrome-b genes and intron 9 of the Z chromosome specific ACO1 gene to reconstruct a phylogeny of the genus. The resulting trees were used to reconstruct a biogeographic history of Phoenicurus, and to date diversification events. We also analysed the relationship between node age and sympatry to determine the geographic mode of speciation in the genus. Our data suggest a very late Miocene, Himalayan origin for Phoenicurus. Diversification and colonization of other parts of Eurasia, as well as Northwest Africa, continued through the Pleistocene, with a rapid pulse of speciation in the late Pliocene. Allopatric speciation was the dominant mode of speciation in Phoenicurus, despite extensive distributional overlaps in the Himalayas where ecological conditions are amenable to speciation in sympatry. Our results, along with several other studies, suggest an emerging pattern where the Himalayas served as a source area for montane specialist avian lineages that subsequently colonized other Palaearctic regions.     

Rapid fluorescent visualization of multiple NAD(P)H oxidoreductases in homogenate,permeabilized cells,and tissue slices

Intracellular NAD(P)H oxidoreductases are a class of diverse enzymes that are the key players in a number of vital processes. The method we present and validate here is based on the ability of many NAD(P)H oxidoreductases to reduce the superoxide probe lucigenin, which is structurally similar to flavins, to its highly fluorescent water-insoluble derivative dimethylbiacridene. Two modifications of the method are proposed: (i) an express method for tissue homogenate and permeabilized cells in suspensions and (ii) a standard procedure for cells in culture and acute thin tissue slices. The method allows one to assess, visualize, and localize, using fluorescent markers of cellular compartments, multiple NADH and NADPH oxidoreductase activities. The application of selective inhibitors (e.g., VAS2870, a NOX2 inhibitor; plumbagin, a NOX4 inhibitor) allows one to distinguish and compare specific NAD(P)H oxidoreductase activities in cells and tissues and to attribute them to known enzymes. The method is simple, rapid, and flexible. It can be easily adapted to a variety of tasks. It will be useful for investigations of the role of various NAD(P)H oxidoreductases in a number of physiological and pathophysiological processes.     

Fluorescence characteristics and photophysical parameters of light-harvesting chlorophyll <Emphasis Type="Italic">a/b</Emphasis> complex aggregates

Fluorescence characteristics and molecular photophysical parameters of light-harvesting chlorophyll a/b complexes isolated from pea were studied in relation to their aggregation state. The aggregate size was varied by changing the Triton X-100 concentration from 0 to 0.23 mM at a chlorophyll concentration of 2.45 μg/ml. Molecular photophysical parameters were determined with laser fluorimetry. Dispersion of large aggregates into smaller ones drastically decreased the intensity of low-temperature (77 K) fluorescence at 700 nm, reduced the singlet-singlet annihilation rate by more than two orders of magnitude, and prolonged the fluorescence lifetime from 0.16 to 3.2 ns.     

Experience on clinical application of positron emission tomography with a new radiopharmaceutical preparation sodium 11C-butyrate in differential diagnosis of pathological volume in brain formation

The study was aimed to investigate the possibilities of the application of a new radiopharmaceutical--"Sodium butyrate, [1-(11)C]" (11C-Butyrate) for differential diagnosis of pathological volume brain formations. Positron emission tomography (PET) ("Ecat Exact 47", Siemens) of the brain was performed in 24 patients (14 male & 10 female, aged 19-56). The scanning was carried out as static scan 4-5 min after intravenous administration of 250-350 Mbq 11C-Butyrate and proceeded within 15-20 min. In addition PET with 18F-FDG was performed in all patients. The data had been verified histologically and morphologically. In 15 out of 24 patients the brain malignant tumor has been discovered, in 4 patients--benign tumors, in 5--postoperative cysts. Results of the studies showed that the ratio tumor/normal tissue in case of 11C-Butyrate and 18F-FDG application proved to be comparable for all studied hystological types of tumors. Malignant tumors in these cases had been visualized as a hot sports-fokci of increased uptake 11C-Butyrate (ratio > 1). The obtained data testify to the possibility of 11C-Butyrate application for differential diagnosis of the pathological volumic brain formation.     

Clinical experience with positron emission tomography with 2-fluorine, 18F-2-deoxy-d-glucose used for the diagnosis of malignant breast neoplasms

The aim of the study was to evaluate sensitivity and specificity of positron emission tomography (PET) and 18F-fluorodesoxyglucose (18F-FDG) in breast cancer diagnosis and to assess tumor dissemination. Sixty two patients were examined: 10 without mammary disease, 10 with fibrous cystic mastopathy, and 42 with breast cancer, which was hystologically verified. PET scanning was recorded in the "Whole body" mode 70-90 min later administration of 370-420 MBq 18F-FDG. It was shown that PET has a high diagnostic accuracy in breast cancer detection. There were no False-positive cases in our investigations. PET scanning in the "Whole body" mode was allowed to assess dissemination of tumor process with high accuracy. Metastatic involvement of local lymph nodes was detected in 82.8% cases and bone metastases--86% in cases.     

Electrically Contacted Bienzyme‐Functionalized Mesoporous Carbon Nanoparticle Electrodes: Applications for the Development of Dual Amperometric Biosensors and Multifuel‐Driven Biofuel Cells

The capping of electron relay units in mesoporous carbon nanoparticles (MPC NPs) by crosslinking of different enzymes on MPC NPs matrices leads to integrated electrically contacted bienzyme electrodes acting as dual biosensors or as functional bienzyme anodes and cathodes for biofuel cells. The capping of ferrocene methanol and methylene blue in MPC NPs by the crosslinking of glucose oxidase (GOx) and horseradish peroxidase (HRP) yields a functional sensing electrode for both glucose and H₂O₂, which also acts as a bienzyme cascaded system for the indirect detection of glucose. A MPC NP matrix, loaded with ferrocene methanol and capped by GOx/lactate oxidase (LOx), is implemented for the oxidation and detection of both glucose and lactate. Similarly, MPC NPs, loaded with 2,2′‐azino‐bis(3‐ethylbenzo­thiazoline‐6‐sulphonic acid), are capped with bilirubin oxidase (BOD) and catalase (Cat), to yield a bienzyme O₂ reduction cathode. A biofuel cell that uses the bienzyme GOx/LOx anode and the BOD/Cat cathode, glucose and/or lactate as fuels, and O₂ and/or H₂O₂ as oxidizers is assembled, revealing a power efficiency of ≈90 μW cm^?2 in the presence of the two fuels. The study demonstrates that multienzyme MPC NP electrodes may improve the performance of biofuel cells by oxidizing mixtures of fuels in biomass.     

Mitochondrial DNA suggests independent evolutionary history and population decline of the Menzbir’s pipit (Anthus [gustavi] menzbieri)

In this study we use mtDNA ND2 gene (1041 bp) to evaluate the relationship between Menzbir’s (Anthus [gustavi] menzbieri) and Pechora (A. [g.] gustavi) pipits. Menzbir’s pipit is listed in the regional Red Data Book as a distinct, rare species with a small range. We obtained 18 Pechora pipit samples from two localities and 8 Menzbir’s pipit samples from a single locality. Sequences of the two taxa appear reciprocally monophyletic and are separated by 6 substitutions (0.6% divergence). Differences between the taxa explained 62.4% of the variation in our dataset. Differences among individuals within localities explained 34.8%, whereas differences between the two Pechora pipit localities explained only 2.8%. Mismatch distributions suggest that unlike the Pechora pipit localities, which either have experienced recent population growth or sustain a stable population size, the Menzbir’s pipit population may be declining. Our results suggest distinct taxonomic and conservation status for the Menzbir’s pipit.     

A plausible mechanism for auxin patterning along the developing root

Background

Recent experimental work has uncovered some of the genetic components required to maintain the Arabidopsis thaliana root stem cell niche (SCN) and its structure. Two main pathways are involved. One pathway depends on the genes SHORTROOT and SCARECROW and the other depends on the PLETHORA genes, which have been proposed to constitute the auxin readouts. Recent evidence suggests that a regulatory circuit, composed of WOX5 and CLE40, also contributes to the SCN maintenance. Yet, we still do not understand how the niche is dynamically maintained and patterned or if the uncovered molecular components are sufficient to recover the observed gene expression configurations that characterize the cell types within the root SCN. Mathematical and computational tools have proven useful in understanding the dynamics of cell differentiation. Hence, to further explore root SCN patterning, we integrated available experimental data into dynamic Gene Regulatory Network (GRN) models and addressed if these are sufficient to attain observed gene expression configurations in the root SCN in a robust and autonomous manner.

Results

We found that an SCN GRN model based only on experimental data did not reproduce the configurations observed within the root SCN. We developed several alternative GRN models that recover these expected stable gene configurations. Such models incorporate a few additional components and interactions in addition to those that have been uncovered. The recovered configurations are stable to perturbations, and the models are able to recover the observed gene expression profiles of almost all the mutants described so far. However, the robustness of the postulated GRNs is not as high as that of other previously studied networks.

Conclusions

These models are the first published approximations for a dynamic mechanism of the A. thaliana root SCN cellular pattering. Our model is useful to formally show that the data now available are not sufficient to fully reproduce root SCN organization and genetic profiles. We then highlight some experimental holes that remain to be studied and postulate some novel gene interactions. Finally, we suggest the existence of a generic dynamical motif that can be involved in both plant and animal SCN maintenance.     

Mathematical model of auxin distribution in the plant root

Regulation of plant growth and development by auxin is mediated by the hormone controlled distribution and dose-dependent mechanisms of its action. A mathematical model is proposed, which described the distribution of auxin in the cells extending along the central axis of the Arabidopsis thaliana root. This model reproduces qualitatively both auxin distribution in cells of the root central axis under the normal conditions and under the conditions of decreased active transport and the recovery of auxin distribution and related meristem restoration during root regeneration after ablation of its tip. Different types of distribution of the auxin concentration over the vertical root axis are described, possible variants of root growth and lateral roots formation are proposed, and biological interpretation is given to different regimes of model behavior.     

137Cs distribution and accumulation in organs and tissues of sheep in the event of chronic consumption of contaminated fodder in the area of the Chernobyl NPP accident

The regularities of 137Cs distribution and accumulation in organs and tissues of sheep on a farm located in the Chernobyl accidental zone were experimentally estimated. The distribution pattern of 137Cs concentration in organs and tissues is found to depend on the duration of the radionuclide uptake with the ration. During the first 24 h the highest 137Cs concentration is reported in the parenchymal organs; starting from day 30 muscular tissue and kidneys rank first, whereas in the other organs and tissues 137Cs concentration is 1.5-2 times lower. By 137Cs content and accumulation rate the study organs are arranged in a declining order as follows: muscles > > skin > liver > kidneys > heart > spleen. The mathematical models were devised describing the dynamics of increasing with time in 137Cs concentration in muscles, liver and skin. The methodology is suggested for the prediction of levels of 137Cs contamination of the muscular tissue of sheep. The time periods were regulated for sheep feeding with 137Cs contaminated fodder that ensure the production of mutton the radionuclide concentration in which meets the sanitary-hygienic standards.