Evidence for an Astrocyte-Derived Vasorelaxing Factor with Properties Similar to Nitric Oxide

To determine whether astrocytes release nonprostanoid vasodilators, cells on microcarrier beads were superfused with various agents in the presence of indomethacin, and the effluent was bioassayed and also analyzed for nitric oxide by a chemiluminescence technique. Bradykinin and A23187 induced release of a factor that relaxed arterial rings, an effect that was blocked by hemoglobin. The effluent contained either nitric oxide or a related compound that could be reduced to nitric oxide. Production of this factor was competitively inhibited by the arginine analogs NG-nitro-L-arginine and NG-methyl-L-arginine and could be restored with L-arginine. Quisqualate and norepinephrine were also effective in causing the release of nitric oxide from astroglial cells. Thus, astrocyte-derived relaxing factor has properties similar to those of an endothelium- and neuron-derived relaxing factor.     

Mapping of mutations associated with neurovirulence in monkeys infected with Sabin 1 poliovirus revertants selected at high temperature.

Poliovirus type 1 neurovirulence is difficult to analyze because of the 56 mutations which differentiate the neurovirulent Mahoney strain from the attenuated Sabin strain. We have isolated four neurovirulent mutants which differ from the temperature-sensitive parental Sabin 1 strain by only a few mutations, using selection for temperature resistance: mutant S(1)37C1 was isolated at 37.5 degrees C, S(1)38C5 was isolated at 38.5 degrees C, and S(1)39C6 and S(1)39C10 were isolated at 39.5 degrees C. All four mutants had a positive reproductive capacity at supraoptimal temperature (Rct+ phenotype). Mutant S(1)37C1 induced paralysis in two of four cynomolgus monkeys, and the three other mutants induced paralysis in four of four monkeys. The lesion score increased from the S(1)37C1 mutant to the S(1)39 mutants. To map the mutations associated with thermoresistance and neurovirulence, we sequenced all regions in which the Sabin 1 genome differs from the Mahoney genome. The S(1)37C1 mutant had one mutation in the 5' noncoding region and another in the 3' noncoding region. Mutant S(1)38C5 had these mutations plus another mutation in the 3D polymerase gene. The S(1)39 mutants had three additional mutations in the capsid protein region. The mutations were located at positions at which the Sabin 1 and Mahoney genomes differ, except for the mutation in the 5' noncoding region. The noncoding-region mutations apparently confer a low degree of neurovirulence. The 3D polymerase mutation, which distinguishes S(1)38C5 and S(1)39 mutants from S(1)37C1, is probably responsible for the high neurovirulence of S(1)38C5 and S(1)39 mutants. The capsid region mutations may contribute to the neurovirulence of the S(1)39 mutants, which was the highest among the mutants.     

Estimation of the hazards ratio in two grouped samples

A simple estimator of the hazards ratio of two grouped samples is proposed. If the number of time grouping intervals is fixed, the following asymptotics hold: unbiasedness, and full efficiency when the true hazards ratio is 1 and the probability of failure in each interval is small. Under the latter condition, the estimator is equivalent to "MHP" estimator (Mantel-Haenszel estimator for a Poisson model). Simulations show that this estimator performs better than others when grouping is coarse. An asymptotically unbiased estimator of its variance is proposed.     

The impact of flooding on aquatic ecosystem services

Flooding is a major disturbance that impacts aquatic ecosystems and the ecosystem services that they provide. Predicted increases in global flood risk due to land use change and water cycle intensification will likely only increase the frequency and severity of these impacts. Extreme flooding events can cause loss of life and significant destruction to property and infrastructure, effects that are easily recognized and frequently reported in the media. However, flooding also has many other effects on people through freshwater aquatic ecosystem services, which often go unrecognized because they are less evident and can be difficult to evaluate. Here, we identify the effects that small magnitude frequently occurring floods (<?10-year recurrence interval) and extreme floods (>?100-year recurrence interval) have on ten aquatic ecosystem services through a systematic literature review. We focused on ecosystem services considered by the Millennium Ecosystem Assessment including: (1) supporting services (primary production, soil formation), (2) regulating services (water regulation, water quality, disease regulation, climate regulation), (3) provisioning services (drinking water, food supply), and (4) cultural services (aesthetic value, recreation and tourism). The literature search resulted in 117 studies and each of the ten ecosystem services was represented by an average of 12?±?4 studies. Extreme floods resulted in losses in almost every ecosystem service considered in this study. However, small floods had neutral or positive effects on half of the ecosystem services we considered. For example, small floods led to increases in primary production, water regulation, and recreation and tourism. Decision-making that preserves small floods while reducing the impacts of extreme floods can increase ecosystem service provision and minimize losses.     

Watershed ‘chemical cocktails’: forming novel elemental combinations in Anthropocene fresh waters

In the Anthropocene, watershed chemical transport is increasingly dominated by novel combinations of elements, which are hydrologically linked together as ‘chemical cocktails.’ Chemical cocktails are novel because human activities greatly enhance elemental concentrations and their probability for biogeochemical interactions and shared transport along hydrologic flowpaths. A new chemical cocktail approach advances our ability to: trace contaminant mixtures in watersheds, develop chemical proxies with high-resolution sensor data, and manage multiple water quality problems. We explore the following questions: (1) Can we classify elemental transport in watersheds as chemical cocktails using a new approach? (2) What is the role of climate and land use in enhancing the formation and transport of chemical cocktails in watersheds? To address these questions, we first analyze trends in concentrations of carbon, nutrients, metals, and salts in fresh waters over 100 years. Next, we explore how climate and land use enhance the probability of formation of chemical cocktails of carbon, nutrients, metals, and salts. Ultimately, we classify transport of chemical cocktails based on solubility, mobility, reactivity, and dominant phases: (1) sieved chemical cocktails (e.g., particulate forms of nutrients, metals and organic matter); (2) filtered chemical cocktails (e.g., dissolved organic matter and associated metal complexes); (3) chromatographic chemical cocktails (e.g., ions eluted from soil exchange sites); and (4) reactive chemical cocktails (e.g., limiting nutrients and redox sensitive elements). Typically, contaminants are regulated and managed one element at a time, even though combinations of elements interact to influence many water quality problems such as toxicity to life, eutrophication, infrastructure corrosion, and water treatment. A chemical cocktail approach significantly expands evaluations of water quality signatures and impacts beyond single elements to mixtures. High-frequency sensor data (pH, specific conductance, turbidity, etc.) can serve as proxies for chemical cocktails and improve real-time analyses of water quality violations, identify regulatory needs, and track water quality recovery following storms and extreme climate events. Ultimately, a watershed chemical cocktail approach is necessary for effectively co-managing groups of contaminants and provides a more holistic approach for studying, monitoring, and managing water quality in the Anthropocene.     

Crystallization and preliminary X-ray analysis of the cytoplasmic domain of human erythrocyte band 3

A cytoplasmic domain of the human erythrocyte membrane protein band 3 (M_r = 42,500), residues 1–379, expressed in and purified from E. coli, has been crystallized by the method of vapor diffusion in sitting drops with subsequent streak-seeding at room temperature. Initial crystals were grown from solutions containing 65–68% saturated ammonium sulfate at pH 4.9 and 2 mg/ml protein. Subsequent streak-seeding into solutions of 50–53% ammonium sulfate at pH 4.9 and 7 mg/ml protein produced single crystals suitable fur X-ray analysis, which contained pure protein as revealed by gel electrophoresis. The crystals belong to the monoclinic space group C2 with cell dimensions of a = 178.8 Å, b = 90.5 Å, c = 122.1 Å, and β = 131.3° and diffract at least to 2.7 Å resolution (at 100 K). A self-rotation function shows the presence of approximate 222 local symmetry. © 1995 Wiley-Liss, Inc.     

Physical and structural properties of taurine and taurine analogues

Summary In a variety of mammalian species it has been established that taurine is a necessary component of the visual system, however, the exact mechanism(s) as to the function of taurine is(are) elusive. Additionally, taurine is speculated to be a membrane stabilizer by interacting with phospholipids and a regulator of protein phosphorylation. Therefore the inhibition by taurine and taurine analogues of the phosphorylation of an 20 kDa protein present in the mitochondrial fraction of the rat retina has been investigated using computational methods. Correlations between molecular weight, molecular volume, and calculated pKa values vs. IC₅₀ values are reported. These data appear to support the hypotheses according to Lombardini and Props that the inhibition of the phosphorylation of an 20kDa protein by taurine and taurine analogues is dependent on (i) the critical distance between the nitrogen and sulfur atoms in the taurine moiety (S-C-C-N) of the analogue; (ii) the environment of the nitrogen atom in the taurine analogue (saturated ring vs. unsaturated ring); and (iii) the placement of both the sulfur and nitrogen atoms not being present simultaneously in the ring structure. Using computational methods we present results that support hypotheses (i) and (ii).     

The impact of structural genomics: the first quindecennial

The period 2000–2015 brought the advent of high-throughput approaches to protein structure determination. With the overall funding on the order of $2 billion (in 2010 dollars), the structural genomics (SG) consortia established worldwide have developed pipelines for target selection, protein production, sample preparation, crystallization, and structure determination by X-ray crystallography and NMR. These efforts resulted in the determination of over 13,500 protein structures, mostly from unique protein families, and increased the structural coverage of the expanding protein universe. SG programs contributed over 4400 publications to the scientific literature. The NIH-funded Protein Structure Initiatives alone have produced over 2000 scientific publications, which to date have attracted more than 93,000 citations. Software and database developments that were necessary to handle high-throughput structure determination workflows have led to structures of better quality and improved integrity of the associated data. Organized and accessible data have a positive impact on the reproducibility of scientific experiments. Most of the experimental data generated by the SG centers are freely available to the community and has been utilized by scientists in various fields of research. SG projects have created, improved, streamlined, and validated many protocols for protein production and crystallization, data collection, and functional analysis, significantly benefiting biological and biomedical research.     

The nucleotide sequence of poliovirus type 3 leon 12 a1b: comparison with poliovirus type 1.

The complete nucleotide sequence of the genome of the Sabin vaccine strain of poliovirus type 3 (P3/Leon 12 a1 b) has been determined from cDNA cloned in E. coli. The genome comprises a 5' non-coding region of 742 nucleotides, a large open reading frame of 6618 nucleotides (89% of the sequence) and a 3' non-coding region of 72 nucleotides. There is 77.4% base-sequence homology and 89.6% predicted amino-acid homology between types 1 and 3. Conservation of all glutamine-glycine and tyrosine-glycine cleavage sites suggests a mechanism of polyprotein processing similar to that established for poliovirus type 1.