When good fellows get together

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NAD+-dependent DNA ligases of Mycobacterium tuberculosis and Streptomyces coelicolor

Sequencing of the genomes of Mycobacterium tuberculosis H37Rv and Streptomyces coelicolor A3(2) identified putative genes for an NAD+-dependent DNA ligase. We have cloned both open reading frames and overexpressed the protein products in Escherichia coli. In vitro biochemical assays confirm that each of these proteins encodes a functional DNA ligase that uses NAD+ as its cofactor. Expression of either protein is able to complement E. coli GR501, which carries a temperature-sensitive mutation in ligA. Thus, in vitro and in vivo analyses confirm predictions that ligA genes from M. tuberculosis and S. coelicolor are NAD+-dependent DNA ligases

Characterization of a temperature-sensitive DNA ligase from Escherichia coli

DNA ligases are essential enzymes in cells due to their ability to join DNA strand breaks formed during DNA replication. Several temperature-sensitive mutant strains of Escherichia coli, including strain GR501, have been described which can be complemented by functional DNA ligases. Here, it is shown that the ligA251 mutation in E. coli GR501 strain is a cytosine to thymine transition at base 43, which results in a substitution of leucine by phenylalanine at residue 15. The protein product of this gene (LigA251) is accumulated to a similar level at permissive and non-permissive temperatures. Compared to wild-type LigA, at 20 °C purified LigA251 has 20-fold lower ligation activity in vitro, and its activity is reduced further at 42 °C, resulting in 60-fold lower ligation activity than wild-type LigA. It is proposed that the mutation in LigA251 affects the structure of the N-terminal region of LigA. The resulting decrease in DNA ligase activity at the non-permissive temperature is likely to occur as the result of a conformational change that reduces the rate of adenylation of the ligase

A New Geographic Locality and Three New Host Records for Neobenedenia melleni (MacCallum) (Monogenea: Capsalidae)

A new geographic locality record and three new host records for Neobenedenia melleni (MacCallum, 1921) (Monogenea: Capsalidae) are provided. Specimens of N. melleni were collected from the skin of three Florida pompano, Trachinotus carolinus (Linnaeus, 1166)(Carangidae),caught in the northern Gulf of Mexico off Horn Island, Mississippi; from the skin of a bluering angelfish, Pomacanthus annularis (Bloch, 1157) (Pomacanthidae), in the Shark Reef Aquarium at Mandalay Bay, Las Vegas, Nevada; from the skin of a rock greenling, Hexagrammos lagocephalus (Pallas, 1810) (Hexagrammidae), in the Alaska SeaLife Center, Seward, Alaska; and from the skin of two blue-barred ribbon gobies, Oxymetopon cyanoctenosum Klausewitz and Condé, 1981 (Microdesmidae), in a tropical fish clearinghouse in Hayward, California. This is the first published record of the parasite from a microdesmid or wild carangid. Prior to this report, no specimen of N. melleni had been reported from a wild-caught fish in the Gulf of Mexico. The presence of N. melleni in the Gulf of Mexico is particularly noteworthy because this monogenean is a known pathogen of cultured fishes in netpens and recirculating seawater systems

An Integrated Strategy to Decrease Eared Dove Damage in Sunflower Crops

Eared doves (Zenaida auriculata) damage mature sunflowers in Uruguay. Although repellents might be useful as a control method, durability and expense have discouraged their use. In the present report, we describe laboratory, aviary, and field research designed to evaluate methiocarb and calcium carbonate as durable, economical repellents. Calcium carbonate (CaCO3) was as effective as CaCO3 /methiocarb in combination in deterring consumption of sunflowers. Moreover, treating field borders with CaCO3 or the CaCO3 /methiocarb combination was as effective as treating the entire field for at least 12 days. This period is sufficiently long to deter damage to sunflower during the critical period just before harvest. We conclude that CaC03 can provide an economical tool to reduce bird damage to sunflower in Uruguay

Quantum spin Hall effect in two-dimensional metals without spin-orbit coupling

The quantum spin Hall effect has been observed in topological insulators using spin-orbit coupling as the probe, but it has not yet been observed in a metal. An experiment is proposed to measure the quantum spin Hall effect of an electron or hole in a two-dimensional (2D) metal by using the previously unexplored but relativistically generated 2D quantum spin Hall Hamiltonian, but without using spin-orbit coupling. A long cylindrical solenoid lies normally through the inner radius of a 2D metallic Corbino disk. The current $I_S$ surrounding the solenoid produces an azimuthal magnetic vector potential but no magnetic field in the disk. In addition, a radial electric field is generated across the disk by imposing either (a) a potential difference $\Delta v$ or (b) a radial charge current ${\bm I}$ across its inner and outer radii. Combined changes in $I_S$ and in either $\Delta v$ or ${\bm I}$ generate spontaneously quantized azimuthal charge and spin currents. The experiment is designed to measure these quantized azimuthal charge and spin currents in the disk consistently. The quantum Hamiltonians for experiments (a) and (b) are both solved exactly. A method to control the Joule heating is presented, which could potentially allow the quantum spin Hall measurements to be made at room temperature. Extensions of this design to an array of thermally-managed solenoids, each surrounded by thermally-managed stacks of 2D metallic Corbino disks, could function as a quantum computer that could potentially operate at room temperature.Comment: 13 pages, 7 figure

A ‘driving force’ in developing the nation’s forests: The McIntire-Stennis Cooperative Forestry Research Program.

The McIntire-Stennis (M-S) Cooperative Forestry Research Program has provided fundamental support for creating and strengthening forestry research and graduate training efforts at colleges and universities across the nation for nearly 50 years. M-S funding has helped produce thousands of forestry scientists and other research professionals, and M-S–supported research has provided critical basic understanding and applied solutions to extend the benefits that flow from forests and related rangelands across the nation over time. The 1962 legislation that created the M-S program authorized funding of up to one-half of the funds appropriated for federal forestry research conducted directly by the USDA. Throughout the program’s history, however, M-S appropriations have been far below the authorized level. In 2012, the M-S program’s 50th anniversary will be celebrated. Congress and the President therefore have a truly significant “golden anniversary” opportunity to strengthen the nation’s investment in research and training that represents an essential and powerful “driving force behind progress” in sustaining forests for ecological, economic, and social benefits for present and future generations

Soil biocrusts affect metabolic response to hydration on dunes in west Queensland, Australia

Soil biocrusts, formed from communities of microbes and their extracellular products are a common feature of dryland soil surfaces. Biocrust organisms are only intermittently metabolically active, but due to their ubiquity they make a significant contribution to the carbon cycle. Quantification of the controls and insights into the interlinked process of photosynthesis and respiration are essential to enhancing our understanding of the carbon cycle in the world’s drylands. Yet, there have been relatively few field studies investigating controls on both biocrust photosynthesis and respiration. We undertook field-based experiments at two dune sites during the dry season in Diamantina National Park in Queensland, Australia to determine how biocrust hydration and illumination affect soil CO2 flux and photosynthesis. Static chambers and an infra-red gas analyser were used to quantify soil CO2 flux, and a fluorometer and a CFImager were used to determine a range of photosynthetic parameters in the field and laboratory respectively. When dry, biocrust photosynthetic activity was not detected and soil CO2 flux was very low irrespective of biocrust cover. Hydration led to a large and immediate increase in CO2 flux, which was more pronounced in the presence of biocrusts and on the dune with thinner biocrusts. Hydration also initiated the onset of photosynthesis in some biocrusts, which was greatest under low light conditions and sustained with further hydration. There were only infrequent periods of net CO2 uptake to the soil, occurring when CO2 uptake due to photosynthetic activity was less than background soil CO2 flux. Chlorophyll fluorescence imaging indicated biocrust spatial heterogeneity was evident at the cm scale where microtopography creates a myriad of environments for different crust organisms. Our findings demonstrate that biocrusts are highly spatially heterogenetic at both landscape and small scale, which suggests the maintenance of biocrust spatial diversity is likely to be key to imparting resilience to changing climate and disturbance. As well as reaffirming the importance of biocrusts for the carbon cycle in dryland dune soils the study demonstrates that biocrust respiration and photosynthesis respond differently to hydration and shading. This adds an unpredictability to the distribution of soil carbon stocks and the gaseous exchanges of CO2 between the surface and atmosphere. Future changes to precipitation and increased temperatures are likely to reduce soil moisture across much of the Australian interior and consequently biocrusts may experience a decline in biomass, structure, and function which could have significant repercussions beyond carbon stocks.Natural Environment Research Counci

Epigraph hemagglutinin vaccine induces broad cross-reactive immunity against swine H3 influenza virus

Influenza A virus infection in swine impacts the agricultural industry in addition to its zoonotic potential. Here, we utilize epigraph, a computational algorithm, to design a universal swine H3 influenza vaccine. The epigraph hemagglutinin proteins are delivered using an Adenovirus type 5 vector and are compared to a wild type hemagglutinin and the commercial inactivated vaccine, FluSure. In mice, epigraph vaccination leads to significant cross-reactive antibody and T-cell responses against a diverse panel of swH3 isolates. Epigraph vaccination also reduces weight loss and lung viral titers in mice after challenge with three divergent swH3 viruses. Vaccination studies in swine, the target species for this vaccine, show stronger levels of cross-reactive antibodies and T-cell responses after immunization with the epigraph vaccine compared to the wild type and FluSure vaccines. In both murine and swine models, epigraph vaccination shows superior cross-reactive immunity that should be further investigated as a universal swH3 vaccine

Analysis of ligation and DNA binding by Escherichia coli DNA ligase (LigA).

NAD+-dependent DNA ligases are essential enzymes in bacteria, with the most widely studied of this class of enzymes being LigA from Escherichia coli. NAD+-dependent DNA ligases comprise several discrete structural domains, including a BRCT domain at the C-terminus that is highly-conserved in this group of proteins. The over-expression and purification of various fragments of E. coli LigA allowed the investigation of the different domains in DNA-binding and ligation by this enzyme. Compared to the full-length protein, the deletion of the BRCT domain from LigA reduced in vitro ligation activity by 3-fold and also reduced DNA binding. Using an E. coli strain harbouring a temperature-sensitive mutation of ligA, the over-expression of protein with its BRCT domain deleted enabled growth at the non-permissive temperature. In gel-mobility shift experiments, the isolated BRCT domain bound DNA in a stable manner and to a wider range of DNA molecules compared to full LigA. Thus, the BRCT domain of E. coli LigA can bind DNA, but it is not essential for DNA nick-joining activity in vitro or in vivo