Phenological shifts compensate warming-induced drought stress in southern Siberian Scots pines     

Arzac  Alberto  Tychkov  Ivan  Rubtsov  Alexey  Tabakova  Maria A.  Brezhnev  Ruslan  Koshurnikova  Natalia  Knorre  Anastasia  Büntgen  Ulf 《European Journal of Forest Research》2021,140(6):1487-1498

European Journal of Forest Research - Global climate change impacts the functioning and productivity of forest ecosystems at various spatiotemporal scales across a wide range of biomes. Although...  相似文献   

A low genomic number of recessive lethals in natural populations of bluefin killifish and zebrafish     

McCune AR  Fuller RC  Aquilina AA  Dawley RM  Fadool JM  Houle D  Travis J  Kondrashov AS 《Science (New York, N.Y.)》2002,296(5577):2398-2401

Despite the importance of selection against deleterious mutations in natural populations, reliable estimates of the genomic numbers of mutant alleles in wild populations are scarce. We found that, in wild-caught bluefin killifish Lucania goodei (Fundulidae) and wild-caught zebrafish Danio rerio (Cyprinidae), the average numbers of recessive lethal alleles per individual are 1.9 (95% confidence limits 1.3 to 2.6) and 1.4 (95% confidence limits 1.0 to 2.0), respectively. These results, together with data on several Drosophila species and on Xenopus laevis, show that phylogenetically distant animals with different genome sizes and numbers of genes carry similar numbers of lethal mutations.  相似文献   

h/e magnetic flux modulation of the energy gap in nanotube quantum dots     

Coskun UC  Wei TC  Vishveshwara S  Goldbart PM  Bezryadin A 《Science (New York, N.Y.)》2004,304(5674):1132-1134

We report experiments on quantum dot single-electron-tunneling (SET) transistors made from short multiwall nanotubes and threaded by magnetic flux. Such systems allow us to probe the electronic energy spectrum of the nanotube and its dependence on the magnetic field. Evidence is provided for the interconversion between gapped (semiconducting) and ungapped (metallic) states. Our tubes exhibit h/e-period magnetic flux dependence, in agreement with simple tight-binding calculations.  相似文献   

Influence of climate change,fire and harvest on the carbon dynamics of black spruce in Central Canada     

Oleg Chertov  Jagtar S. Bhatti  Alexander Komarov  Alexey Mikhailov  Sergey Bykhovets 《Forest Ecology and Management》2009

The results of EFIMOD simulations for black spruce (Picea mariana [Miller]) forests in Central Canada show that climate warming, fire, harvesting and insects significantly influence net primary productivity (NPP), soil respiration (Rs), net ecosystem production (NEP) and pools of tree biomass and soil organic matter (SOM). The effects of six climate change scenarios demonstrated similar increasing trends of NPP and stand productivity. The disturbances led to a strong decrease in NPP, stand productivity, soil organic matter (SOM) and nitrogen (N) pools with an increase in CO₂ emission to the atmosphere. However the accumulated NEP for 150 years under harvest and fire fluctuated around zero. It becames negative only at a more frequent disturbance regime with four forest fires during the period of simulation. The results from this study show that changes in climate and disturbance regimes might substantially change the NPP as well as the C and N balance, resulting in major changes in the C pools of the vegetation and soil under black spruce forests.  相似文献   

Kinetics of human and horse sera cholinesterases inhibition with solanaceous glycoalkaloids: Study by potentiometric biosensor     

Iryna V. Benilova  Valentina N. Arkhypova  Nicole Jaffrezic-Renault  Alexey P. Soldatkin 《Pesticide biochemistry and physiology》2006,86(3):203-210

The kinetics of inhibition of human and horse sera butyryl cholinesterases by solanaceous glycoalkaloids α-solanine, α-chaconine and tomatine has been studied by means of a potentiometric biosensor based on pH-sensitive field effect transistors (pH-FETs). Using acetyl- and butyryl choline as substrates, the optimal pH and the apparent kinetic parameters (K_mapp, V_maxapp) of immobilized cholinesterases have been calculated in the absence of inhibitors. All studied glycoalkaloids were reversible inhibitors of both butyryl cholinesterases, and inhibited the horse and human immobilized enzymes in competitive and mixed modes, respectively. The affinity of each enzyme towards α-solanine, α-chaconine and tomatine has been estimated through calculation of apparent inhibition constants K_iapp and inhibition coefficients I₅₀. An application of the butyryl cholinesterases studied in the biosensors for glycoalkaloids determination in the concentration range of 10⁻⁷ to 10⁻⁴ M has been discussed.  相似文献   

Anthropogenic Ammonia Emissions in the Former USSR in 1990     

Ryaboshapko  Alexey G. 《Water, air, and soil pollution》2001,130(1-4):205-210

Ammonia emissions originate from different and widely distributed sources. The bulk of anthropogenic NH₃ emissions are connected with agriculture and a smaller part with industry. The default emission factors recommended by the Economical Commission for Europe are applied to evaluate NH₃ emissions from the former USSR. The following categories of agricultural activities are considered: cattle, pigs, poultry, horses, sheep, goats, fur animals, rabbits, reindeers and fertiliser application. Human and home pet metabolism as a source of NH₃ is also considered. Industrial sources include combustion processes and production of fertilisers, ammonia, coke. Emissions from landfills are also considered. Uncertainties of emission values for each category of sources are estimated. Ammonia emissions are calculated separately for all former republics for the year 1990. The total emissions for Russia are spatially distributed over the territory with 1° × 1° resolution. The data on NH₃ emissions can be used in model calculations of long-range (transboundary) transport of acidifying compounds.  相似文献   

Dual activation of the Drosophila toll pathway by two pattern recognition receptors     

Gobert V  Gottar M  Matskevich AA  Rutschmann S  Royet J  Belvin M  Hoffmann JA  Ferrandon D 《Science (New York, N.Y.)》2003,302(5653):2126-2130

The Toll-dependent defense against Gram-positive bacterial infections in Drosophila is mediated through the peptidoglycan recognition protein SA (PGRP-SA). A mutation termed osiris disrupts the Gram-negative binding protein 1 (GNBP1) gene and leads to compromised survival of mutant flies after Gram-positive infections, but not after fungal or Gram-negative bacterial challenge. Our results demonstrate that GNBP1 and PGRP-SA can jointly activate the Toll pathway. The potential for a combination of distinct proteins to mediate detection of infectious nonself in the fly will refine the concept of pattern recognition in insects.  相似文献   

Structure of Rab GDP-dissociation inhibitor in complex with prenylated YPT1 GTPase     

Rak A  Pylypenko O  Durek T  Watzke A  Kushnir S  Brunsveld L  Waldmann H  Goody RS  Alexandrov K 《Science (New York, N.Y.)》2003,302(5645):646-650

Rab/Ypt guanosine triphosphatases (GTPases) represent a family of key membrane traffic regulators in eukaryotic cells whose function is governed by the guanosine diphosphate (GDP) dissociation inhibitor (RabGDI). Using a combination of chemical synthesis and protein engineering, we generated and crystallized the monoprenylated Ypt1:RabGDI complex. The structure of the complex was solved to 1.5 angstrom resolution and provides a structural basis for the ability of RabGDI to inhibit the release of nucleotide by Rab proteins. Isoprenoid binding requires a conformational change that opens a cavity in the hydrophobic core of its domain II. Analysis of the structure provides a molecular basis for understanding a RabGDI mutant that causes mental retardation in humans.  相似文献   

Building programmable jigsaw puzzles with RNA     

Chworos A  Severcan I  Koyfman AY  Weinkam P  Oroudjev E  Hansma HG  Jaeger L 《Science (New York, N.Y.)》2004,306(5704):2068-2072

One challenge in supramolecular chemistry is the design of versatile, self-assembling building blocks to attain total control of arrangement of matter at a molecular level. We have achieved reliable prediction and design of the three-dimensional structure of artificial RNA building blocks to generate molecular jigsaw puzzle units called tectosquares. They can be programmed with control over their geometry, topology, directionality, and addressability to algorithmically self-assemble into a variety of complex nanoscopic fabrics with predefined periodic and aperiodic patterns and finite dimensions. This work emphasizes the modular and hierarchical characteristics of RNA by showing that small RNA structural motifs can code the precise topology of large molecular architectures. It demonstrates that fully addressable materials based on RNA can be synthesized and provides insights into self-assembly processes involving large populations of RNA molecules.  相似文献   

Sensitivity and specificity improvement of an ion sensitive field effect transistors-based biosensor for potato glycoalkaloids detection     

Korpan YI  Raushel FM  Nazarenko EA  Soldatkin AP  Jaffrezic-Renault N  Martelet C 《Journal of agricultural and food chemistry》2006,54(3):707-712

Butyryl cholinesterase of different origin along with variations of the time of enzyme immobilization on the potentiometric transducer surface is offered to control the ion sensitive field effect transistor (ISFET)-based biosensor sensitivity. Because butyryl cholinesterase has been already used to develop the sensors for heavy metals, organophosphorus/carbamate pesticides, and steroidal glycoalkaloids analysis, the present study has been focused on the investigation and adjustment of the ISFET-based biosensor specificity exclusively to the glycoalkaloids. Utilization of ethylendiaminetetracetate (a complexon of heavy metal ions) and phosphotriesterase (a highly efficient catalyst for the hydrolysis of organophosphorus compounds) enabled the highly specific determination of glycoalkaloids at the background of lead and mercury (up to 500 microM of ions concentration) and paraoxon (up to 100 microM of pesticide concentration). The developed biosensor has been validated for glycoalkaloids detection in potato varieties cultivated in Ukraine, and the results obtained are compared to those measured by the methods of HPLC and TLC.  相似文献