Biological, Physical, and Chemical Properties of Eastern Equine Encephalitis Virus I. Purification and Physical Properties

A new purification procedure was adopted for Eastern equine encephalitis virus which does not subject the virus to pelleting at any stage. Three- to 4-liter volumes were passed through a diethylaminoethyl cellulose column. The virus-containing fractions were banded on a sucrose cushion and finally concentrated in an isopycnic band in a linear sucrose gradient. This method reduced the volume 1,000-fold with a concomitant increase in viral titer, i.e., better than 90% recovery. Numerous criteria have been used to establish that this viral preparation was essentially free from cellular debris and nonviral material. Physical studies on this purified viral product were initiated. The sedimentation coefficient as determined by band sedimentation was 240S, the buoyant density in sucrose was 1.18 g/cc, and the diameter of the virus was 54 nm. From the diameter and the buoyant density it was possible to calculate the molecular weight of a spherical particle. In this case, the calculated molecular weight for Eastern equine encephalitis virus was 58 x 10(6) daltons.     

Cellular uptake of lithium via amino acid transport system A

We now add to the agencies by which cells take up lithium the process of cotransport with neutral amino acids via System A. In the Ehrlich cell various natural and synthetic amino acids, depending on their structure, can cause substantial accelerations of Li⁺ uptake over a considerable range of levels of Na⁺, Li⁺ and H⁺. Half the maximal augmentation of uptake, namely 1.2 mequiv. Li/kg cell water per 15 min, was obtained for 5.4 mM alanine in a double-reciprocal plot. Alanine also stimulated the exodus of Li⁺ from the Ehrlich cell. The human red blood cell, lacking System A as it does, becomes an imperfect model for studying cellular uptake of Li⁺. Until the Li⁺ dependence of amino acid uptake in the reticulocyte is known, reticulocytosis can be suspected of contributing to the interpersonal variations seen in Li⁺-for-Na⁺ exchange.     

Na+/L+ selectivity in transport systemA: Effects of substrate structure

Summary The effect of amino acid structure on the selectivity between Na and Li as co-substrates for transport SystemA in the Ehrlich cell has been explored to localize relative binding positions. By various tests the relative effectiveness of the two cations varies over fivefold. Changes in structure of the amino acid that lower its response to Na tend to decrease its selectivity for Na over Li, but with many exceptions. The higher the Li level required to half-maximize amino acid entry, the slower tends to be the entry attainable for both Li and amino acid. Our attention fell on strong departures from these trends. An atypically fast uptake is produced by Li in the presence of a second amino group pK₂<8.5, in exceptional association with the known fast uptake in Na. The hydroxyl group of serine yields exceptionally strong uptake, whereas hydroxyl groups in restrained orientation (as in threonine and hydroxyprolines) sharply limit co-substrate interaction. Despite the absence of a sidechain, glycine shows unexceptional relative co-substrate responses. A sidechain in the ₂ position, as ind-alanine, lowers tolerance for both ions, an aberration largely corrected by the insertion of a second (₂) methyl group, and surprisingly, even by an N-methyl group. Forl-alanine, an N-methyl group has in contrast unfavorable effects on co-substrate interaction. These factors point to disturbance by the ₂ methyl group of the position taken by the amino acid at the site, largely rectifiable by balancing effects of a second methyl group. They also point to a position of the alkali ion quite close to the -carbon and far from the position taken in SystemASC. Addition of an ethylene bridge between the -methyl groups of (methylamino)-isobutyric acid leads to the strongest discrimination seen against Li⁺ relative to Na⁺, suggesting through crowding of the area that the alkali ion adjoins the three methyl groups of this analog.     

Effects of diverse environmental conditions on {phi}LC3 prophage stability in Lactococcus lactis

The effects of various growth conditions on spontaneous phiLC3 prophage induction in Lactococcus lactis subsp. cremoris IMN-C1814 was analyzed with a half fraction of a 4(4) factorial experimental design. The four factors included in the study were nutrient availability, acidity, osmolarity, and temperature, each applied at four levels. These environmental factors are related to the fermentation processes in the dairy industry, in which bacteriophage attacks on sensitive starter strains are a constant threat to successful fermentation processes. The frequency of spontaneous phiLC3 induction was determined by quantitative analyses of restored DNA attachment sites (attB) on the bacterial chromosomes in a population of lysogenic cells. Statistical analysis revealed that all four environmental factors tested affected phiLC3 prophage stability and that the environmental factors were involved in interactions (interactions exist when the effect of one factor depends on the level of another factor). The spontaneous phiLC3 induction frequency varied from 0.08 to 1.76%. In general, the induction frequency remained at the same rate or decreased when level 1 to 3 of the four environmental factors was applied. At level 4, which generally gave the least favorable growth conditions, the induction frequency was either unchanged, decreased, or increased, depending on the type of stress. It appeared that the spontaneous induction frequency was independent of the growth behavior of the host. It was the environmental growth conditions that were the decisive factor in induction frequency.     

Light and dissolved phosphorus interactively affect microbial metabolism,stoichiometry and decomposition of leaf litter

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Separate and shared lysosomal transport of branched and aromatic dipolar amino acids

Transport systems analogous to the T and L carriers for aromatic and bulky dipolar amino acids in plasma membranes have been characterized in the membranes of intact lysosomes isolated from human fetal skin fibroblasts. While system L appears ubiquitous in plasma membranes, system T has previously been discriminated only in the plasmalemma of human red blood cells and freshly isolated rat hepatocytes. Our findings with the lysosomal systems, provisionally designated tandl, reveal both shared and dissimilar properties with the plasma membrane systems. These properties include a lack of dependency on extralysosomal Na⁺, differential sensitivities to the classical system L analog, 2-aminobicyclo[2.2.1]heptane-2-car☐ylic acid (BCH), and the system T analog, d-tryptophan, as well as susceptibility to thiol modification at the membrane by reactivity with N-ethylmaleimide. A transport system in lysosomes from the FRTL-5 rat thyroid cell line has been described by Bernar et al. ((1986) J. Biol. Chem. 261, 17107–17112) resembles a composite of both carrier systems reported in this work.     

Early supported discharge after stroke in Bergen (ESD Stroke Bergen): three and six months results of a randomised controlled trial comparing two early supported discharge schemes with treatment as usual

Background

Stroke causes lasting disability and the burden of stroke is expected to increase substantially during the next decades. Optimal rehabilitation is therefore mandatory. Early supported discharge (ESD) has previously shown beneficial, but all major studies were carried out more than ten years ago. We wanted to implement and study the results of ESD in our community today with comparisons between ESD and treatment as usual, as well as between two different ESD models.

Methods

Patients with acute stroke were included during a three year period (2008–11) in a randomised controlled study comparing two different ESD models to treatment as usual. The two ESD models differed by the location of treatment: either in a day unit or in the patients’ homes. Patients in the ESD groups were followed by a multi-disciplinary ambulatory team in the stroke unit and discharged home as early as possible. The ESD models also comprised treatment by a multi-disciplinary community health team for up to five weeks and follow-up controls after 3 and 6 months. Primary outcome was modified Rankin Scale (mRS) at six months.

Results

Three-hundred-and-six patients were included. mRS scores and change scores were non-significantly better in the two ESD groups at 3 and 6 months. Within-group improvement from baseline to 3 months was significant in the ESD 1 (p?=?0.042) and ESD 2 (p?=?0.001) groups, but not in the controls. More patients in the pooled ESD groups were independent at 3 (p?=?0.086) and 6 months (p?=?0.122) compared to controls and there also was a significant difference in 3 month change score between them (p?=?0.049). There were no differences between the two ESD groups. Length of stay in the stroke unit was 11 days in all groups.

Conclusions

Patients in the ESD groups tended to be more independent than controls at 3 and 6 months, but no clear statistically significant differences were found. The added effect of supported discharge and improved follow-up seems to be rather modest. The improved stroke treatment of today may necessitate larger patient samples to demonstrate additional benefit of ESD.

Clinical trial registration

Unique identifier: NCT00771771

     

Disparate movement behavior and feeding ecology in sympatric ecotypes of Atlantic cod

Coexistence of ecotypes, genetically divergent population units, is a widespread phenomenon, potentially affecting ecosystem functioning and local food web stability. In coastal Skagerrak, Atlantic cod (Gadus morhua) occur as two such coexisting ecotypes. We applied a combination of acoustic telemetry, genotyping, and stable isotope analysis to 72 individuals to investigate movement ecology and food niche of putative local “Fjord” and putative oceanic “North Sea” ecotypes—thus named based on previous molecular studies. Genotyping and individual origin assignment suggested 41 individuals were Fjord and 31 were North Sea ecotypes. Both ecotypes were found throughout the fjord. Seven percent of Fjord ecotype individuals left the study system during the study while 42% of North Sea individuals left, potentially homing to natal spawning grounds. Home range sizes were similar for the two ecotypes but highly variable among individuals. Fjord ecotype cod had significantly higher δ¹³C and δ¹⁵N stable isotope values than North Sea ecotype cod, suggesting they exploited different food niches. The results suggest coexisting ecotypes may possess innate differences in feeding and movement ecologies and may thus fill different functional roles in marine ecosystems. This highlights the importance of conserving interconnected populations to ensure stable ecosystem functioning and food web structures.     

Priming of inducible defenses protects Norway spruce against tree-killing bark beetles

Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48-year-old Norway spruce (Picea abies) trees to mass attack by a tree-killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus-inoculated trees and MeJA-treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91-fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus-inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA-treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.