Can the stereoselective effects of the anesthetic isoflurane be accounted for by lipid solubility?

Isoflurane is an inhalational general anesthetic widely used in surgical operations as a racemic mixture of its two optical isomers. The recent availability of pure enantiomers of isoflurane has encouraged their use in experimental studies, and stereoselective effects have now been observed on anesthetic-sensitive neuronal ion channels. Although it has been assumed that such chiral effects demonstrate direct interactions with proteins, it is possible that they could be due to stereoselective interactions with chiral membrane lipids. We have determined the partition coefficients of the two optical isomers of isoflurane between lipid bilayers and water, using racemic isoflurane and gas chromatography with a chiral column. For lipid bilayers of phosphatidylcholine (PC) and 4 mol% phosphatidic acid (PA), both with and without cholesterol (CHOL), we found equal partitioning of the isoflurane optical isomers. The ratios of the S(+) to R(-) isoflurane partition coefficients were (mean +/- SEM): 1.018 +/- 0.010 for bilayers of PC/CHOL/PA (mole ratios 56:40:4) and 1.011 +/- 0.002 for bilayers of PC/PA (mole ratio 96:4). Molar partition coefficients for racemic isoflurane were 49 +/- 4 and 165 +/- 10, respectively. These findings support the view that the stereoselective effects on ion channels observed with isoflurane are due to direct actions on proteins rather than lipids.     

Can members of the south‐western Gila robusta species complex be distinguished by morphological features?

The goal for this project was to re‐examine key morphological characters hypothesized to differentiate Gila intermedia, Gila robusta and Gila nigra and outline methods better suited for making species designations based on morphology. Using a combination of meristic counts, morphological measurements and geometric morphometrics, morphological dissimilarities were quantified among these three putative species. Traditional meristic counts and morphological measurements (i.e. distances between landmarks) were not useful for species identification. Geometric morphometrics, however, identified differences among species, while also suggesting an effect of geographic location on morphological variation. Using canonical variate analysis for the 441 fish sampled in this study, geometric morphometrics accurately predicted true group membership 100% of the time for G. nigra, 97% of the time for G. intermedia and 91% of the time for G. robusta. These results suggest that geometric morphometric analysis is necessary to identify morphological differences among the three species. Geometric morphometric analysis used in this study can be adopted by management officials as a tool to classify unidentified individuals.     

Can the use of physical modalities for pain control be rationalized by the research evidence?

Physical modalities, including cold and heat, are widely used in the conservative management of pain associated with musculoskeletal disorders. This review has critically appraised the literature supporting the use of these modalities in the treatment of musculoskeletal pain. It was concluded that, apart from a few exceptions and in a few types of disorders, existing evidence does not support the use of these modalities in long-term pain control. There was, however, evidence that several modalities, specifically cold and a form of deep heat (shortwave diathermy), do have short-lived analgesic effects and so may contribute to more painfree function in the short term. Further research is clearly warranted to define the short- and long-term therapeutic efficacy of physical modalities in the treatment of musculoskeletal pain to justify their continued use in clinical practice.     

Can the function of the extirpated amygdaloid complex be compensated for by the transplantation of embryonic nerve tissue?

In 20 white rats bilateral coagulation of the amygdalar complex was produced; on the fifth day to one half of them transplantation was performed by introducing stereotaxically on the left side 0.2-0.5 mm3 of the brain embryonal tissue from the corresponding area of the amygdala of 20-days embryo; in control saline was administered. After two months the rats were sacrificed to determine the activity of antiradical defense by superoxide dismutase (SOD) and the level of lipids peroxide oxidation (LPO) in the cerebral cortex. The transplantation decreased LPO even more and increased SOD as compared to amygdalectomy, e. i. caused still greater deviations from the norm (in this meaning--paradoxal effect), what apparently corresponds to intensification of adaptative-compensatory processes caused by amygdalectomy. The transplantation did not reverse the rats behaviour to the initial one and did not eliminate memory defect in the test of conditioned reaction of passive avoidance (like pyrazetam); it had different direction influence on "drinking under current" in conflict situation, only in particular cases approaching it to the norm.     

How Can the Eco‐efficiency of a Region be Measured and Monitored?

The concept of eco-efficiency is commonly referred to as a business link to sustainable development. In this article, ecoefficiency is examined at a regional level as an approach to promoting the competitiveness of economic activities in the Finnish Kymenlaakso region and mitigating their harmful impacts on the environment. The aim is to develop appropriate indicators for monitoring changes in the eco-efficiency of the region. A starting point is to produce indicators for the environmental and economic dimensions of regional development and use them for measuring regional eco-efficiency. The environmental impact indicators are based on a life-cycle assessment method, producing different types of environmental impact indicators: pressure indicators (e.g., emissions of CO₂), impact category indicators (e.g., CO₂ equivalents in the case of climate change), and a total impact indicator (aggregating different impact category indicator results into a single value). Environmental impact indicators based on direct material input, total material input, and total material requirement of the Kymenlaakso region are also assessed. The economic indicators used are the gross domestic product, the value added, and the output of the main economic sectors of Kymenlaakso. In the eco-efficiency assessment, the economic and environmental impact indicators are monitored in the same graph. In a few cases eco-efficiency ratios can also be calculated (the economic indicators are divided by the environmental indicators). Output (= value added + intermediate consumption) is used as an economic indicator related to the environmental impact indicators, which also cover the upstream processes of the region's activities. In the article, we also discuss the strengths and weaknesses of using the different environmental impact indicators.     

Relationships between dental microwear and diet in Carnivora (Mammalia) — Implications for the reconstruction of the diet of extinct taxa

Food consumption causes distinct microwear patterns on teeth, especially in mammals that actively masticate food. Here we perform a microwear analysis to assess the relationships between diet and microwear features of diverse Carnivora. Our database includes approximately 230 individuals of 17 extant species having different diets. We analyse both slicing and grinding facets of M1 and m1. The proposed method is reproducible and allows the differentiation, especially on slicing facets, of microwear poles that are significantly distinct from one another. In carnivorans, the microwear features mainly result from their foraging behavior and the proportion of certain food items consumed. We applied our method to extinct taxa such as the amphicyonid Amphicyon major. The results on the m1 slicing facet indicate dietary similarities between this large Miocene predator and the extant red fox; results from the m1 grinding facet do not have equivalent in extant taxa, however.     

Can the API (RAPID) Coryne system be used for identification of rapidly growing mycobacteria?

Fifty-six strains of rapidly growing mycobacteria (RGM) and 14 strains of aerobic actinomycetes as quality controls (QC) were tested in the API (RAPID) Coryne system version 2. Both groups yielded codes with low identification scores, considerable overlaps, and similar diagnoses. No species-specific codes were observed. Thus, the system would not be useful for the identification of RGM.     

Can the extinction of Melitaea britomartis in NW Italy be explained by unfavourable weather? An analysis by Optimal Interpolation

We investigated possible correlations between climate-related factors and butterfly range restrictions by selecting a study case represented by four populations of Melitaea britomartis, which become ‘simultaneously’ extinct in NW Italy in 1976–1977 without any observable habitat change. To overcome difficulties related to the analysis of past extinctions and hypothesise causal factors, we applied the Optimal Interpolation method, a statistical method used to create a gridded climatological analysis of temperature and precipitation data, to a historical dataset containing all available information on the Italian butterfly fauna. We tested two different hypotheses: (1) the role of climate change, expressed as a general trend in temperature and precipitation data; (2) the role of extreme weather events, expressed as anomalous conditions during the years of extinctions. Our results show that long-term temperature and precipitation data do not present any clear trend at our study site, suggesting that they cannot be involved in the species’ extinction. On the opposite, 1976 and 1977 were climatologically critical for the study area. In particular, 1977 was characterized by the coldest summer in the entire historical dataset (1958–1977), with strong negative temperature anomalies. Moreover, both years experienced unusually many rainy days during spring and summer. The year 1977 in particular, was the wettest within the entire historical dataset. The years of M. britomartis populations’ extinction were characterised by many more cold and rainy days than usual during the species’ flight period. These results allow us to hypothesize a strong component of unfavourable weather in driving populations’ extinction.     

Can yeast be used to study mitochondrial diseases? Biolistic tRNA mutants for the analysis of mechanisms and suppressors

Base substitutions equivalent to those causing human pathologies have been introduced in yeast mitochondrial tRNA genes. These mutants can be utilized as flexible tools to investigate the molecular aspects of mitochondrial diseases and identify correcting genes. We show that for all studied tRNA mutations (including an homoplasmic one in tRNA^Val) the severity of phenotypes follows the same trend in four different nuclear backgrounds. Correcting genes include TUF1 and genes encoding aminoacyl-tRNA synthetase. The effect of suppressors was analyzed by Northern blot. Mutated leucyl-tRNA synthetase with highly reduced catalytic activity maintains full suppressing effect, thus suggesting a chaperone-like and/or stabilizing function.     

Unnecessary roughness? Testing the hypothesis that predators destined for molecular gut‐content analysis must be hand‐collected to avoid cross‐contamination

Molecular gut‐content analysis enables detection of arthropod predation with minimal disruption of ecosystem processes. Mass‐collection methods, such as sweep‐netting, vacuum sampling and foliage beating, could lead to regurgitation or rupturing of predators along with uneaten prey, thereby contaminating specimens and compromising resultant gut‐content data. Proponents of this ‘cross‐contamination hypothesis’ advocate hand‐collection as the best way to avoid cross‐contamination. However, hand‐collection is inefficient when large samples are needed, as with most ecological research. We tested the cross‐contamination hypothesis by setting out onto potato plants immature Coleomegilla maculata and Podisus maculiventris that had been fed larvae of either Leptinotarsa decemlineata or Leptinotarsa juncta, or unfed individuals of these predator species along with L. decemlineata larvae. The animals were then immediately re‐collected, either by knocking them vigorously off the plants onto a beat cloth and capturing them en masse with an aspirator (‘rough’ treatment) or by hand‐searching and collection with a brush (‘best practice’). Collected predators were transferred in the field to individual vials of chilled ethanol and subsequently assayed by PCR for fragments of cytochrome oxidase I of L. decemlineata and L. juncta. Ten to 39 per cent of re‐collected fed predators tested positive by PCR for DNA of both Leptinotarsa species, and 14–38% of re‐collected unfed predators contained L. decemlineata DNA. Overall levels of cross‐contamination in the rough (31%) and best‐practice (11%) samples were statistically different and supported the cross‐contamination hypothesis. A pilot study on eliminating external DNA contamination with bleach prior to DNA extraction and amplification gave promising results.     

Cloning and functional analysis of chicory root fructan1‐exohydrolase I (1‐FEH I): a vacuolar enzyme derivedfrom a cell‐wall invertase ancestor? Mass fingerprint of the 1‐FEH I enzyme

This paper describes the cloning and functional analysis of chicory (Cichorium intybus L.) fructan 1-exohydrolase I cDNA (1-FEH I). To our knowledge it is the first plant FEH cloned. Full-length cDNA was obtained by a combination of RT-PCR, 5' and 3' RACE using primers based on N-terminal and conserved amino acid sequences. Electrophoretically purified 1-FEH I enzyme was further analyzed by in-gel trypsin digestion followed by matrix-assisted laser desorption ionization and electrospray time-of-flight tandem mass spectrometry. Functionality of the cDNA was demonstrated by heterologous expression in potato tubers. 1-FEH I takes a new, distinct position in the phylogenetic tree of plant glycosyl hydrolases being more homologous to cell-wall invertases (44-53%) than to vacuolar invertases (38-41%) and fructosyl transferases (33-38%). The 1-FEH I enzyme could not be purified from the apoplastic fluid at significantly higher levels than can be explained by cellular leakage. These and other data suggest a vacuolar localization for 1-FEH I. Also, the pI of the enzyme (6.5) is lower than expected from a typical cell-wall invertase. Unlike plant fructosyl transferases that are believed to have evolved from a vacuolar invertase, 1-FEH I might have evolved from a cell-wall invertase-like ancestor gene that later obtained a vacuolar targeting signal. 1-FEH I mRNA quantities increase in the roots throughout autumn, and especially when roots are stored at low temperature.     

Can the outcomes of mesenchymal stem cell‐based therapy for myocardial infarction be improved? Providing weapons and armour to cells

Use of mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been found to have infarct‐limiting effects in numerous experimental and clinical studies. However, recent meta‐analyses of randomized clinical trials on MSC‐based MI therapy have highlighted the need for improving its efficacy. There are two principal approaches for increasing therapeutic effect of MSCs: (i) preventing massive MSC death in ischaemic tissue and (ii) increasing production of cardioreparative growth factors and cytokines with transplanted MSCs. In this review, we aim to integrate our current understanding of genetic approaches that are used for modification of MSCs to enable their improved survival, engraftment, integration, proliferation and differentiation in the ischaemic heart. Genetic modification of MSCs resulting in increased secretion of paracrine factors has also been discussed. In addition, data on MSC preconditioning with physical, chemical and pharmacological factors prior to transplantation are summarized. MSC seeding on three‐dimensional polymeric scaffolds facilitates formation of both intercellular connections and contacts between cells and the extracellular matrix, thereby enhancing cell viability and function. Use of genetic and non‐genetic approaches to modify MSC function holds great promise for regenerative therapy of myocardial ischaemic injury.     

A meta‐analysis of isolation by distance: relic or reference standard for landscape genetics?

Isolation by distance (IBD) has been a common measure of genetic structure among populations and is based on Euclidean distances among populations. Whereas IBD does not incorporate geographic complexity (e.g. dispersal barriers, corridors) that may better predict genetic structure, a new approach (landscape genetics) joins landscape ecology with population genetics to better model genetic structure. Should IBD be set aside or should it persist as the most simple model in landscape genetics? We evaluated the status of IBD by collecting and analyzing results of 240 IBD data sets among diverse taxa and study systems. IBD typically represented a low proportion of variance in genetic structure (mean r²=0.22) in part because many studies included relatively few populations (mean=11). The number of populations studied (N) was asymptotically related to IBD significance; a study with 9 populations has only 50% probability of significance, while one with >23 populations will have 90% probability of significance. Surprisingly, ectothermic animals were significantly (p=0.0018) more likely to have significant IBD than endotherms, which suggests a metabolic basis underlying gene flow rates. We also observed marginally significant effects on IBD significance for a) taxa in general and b) dispersal modes within actively‐dispersing endotherms. Other factors analyzed (genetic markers, genetic distances, habitats, active or passive dispersal, plant growth form) did not significantly affect IBD, likely related to typical N. For multiple reasons we conclude that IBD should continue as the simplest reference standard against which all other, more complex models should be compared in landscape genetics research.     

Can the topological distribution of membrane spanning amino acid residues be responsible for the recognition of signal peptides by signal peptide peptidases?

Signal peptides are selectively recognized and degraded by membrane associated proteases called as signal peptide peptidases. The hydrolysis of the signal peptide occurs only after its cleavage from the precursor. The possible reasons for this selectivity have been investigated. The results indicate that in signal peptides, leucine residues are clustered to a large extent on the same side of the membrane spanning alpha helix as the polar residues, but are distinctly separated along the length of the axis. Such topological differences in the distribution of amino acids on the surface of the membrane spanning alpha helix may play a crucial role in selective degradation of signal peptides.     

Can microbially-generated hydrogen sulfide account for the rates of U(VI) reduction by a sulfate-reducing bacterium?

In situ remediation of uranium contaminated soil and groundwater is attractive because a diverse range of microbial and abiotic processes reduce soluble and mobile U(VI) to sparingly soluble and immobile U(IV). Often these processes are linked. Sulfate-reducing bacteria (SRB), for example, enzymatically reduce U(VI) to U(IV), but they also produce hydrogen sulfide that can itself reduce U(VI). This study evaluated the relative importance of these processes for Desulfovibrio aerotolerans, a SRB isolated from a U(VI)-contaminated site. For the conditions evaluated, the observed rate of SRB-mediated U(VI) reduction can be explained by the abiotic reaction of U(VI) with the microbially-generated H₂S. The presence of trace ferrous iron appeared to enhance the extent of hydrogen sulfide-mediated U(VI) reduction at 5 mM bicarbonate, but had no clear effect at 15 mM. During the hydrogen sulfide-mediated reduction of U(VI), a floc formed containing uranium and sulfur. U(VI) sequestered in the floc was not available for further reduction.     

All by myself? Meta‐analysis of animal contests shows stronger support for self than for mutual assessment models

Since the 1970's, models based on evolutionary game theory, such as war of attrition (WOA), energetic war of attrition (E‐WOA), cumulative assessment model (CAM) and sequential assessment model (SAM), have been widely applied to understand how animals settle contests. Despite the important theoretical advances provided by these models, empirical evidence indicates that rules adopted by animals to settle contests vary among species. This stimulated recent discussions about the generality and applicability of models of contest. A meta‐analysis may be helpful to answer questions such as: (i) is there a common contest rule to settle contests; (ii) do contest characteristics, such as the occurrence of physical contact during the fight, influence the use of specific contest rules; and (iii) is there a phylogenetic signal behind contest rules? To answer these questions, we gathered information on the relationship between contest duration and traits linked to contestants' resource holding potential (RHP) for randomly paired rivals and RHP‐matched rivals. We also gathered behavioural data about contest escalation and RHP asymmetry. In contests between randomly paired rivals, we found a positive relationship between contest duration and loser RHP but did not find any pattern for winners. We also found a low phylogenetic signal and a similar response for species that fight with and without physical contact. In RHP‐matched rivals, we found a positive relationship between contest duration and the mean RHP of the pair. Finally, we found a negative relation between contest escalation and RHP asymmetry, even though it was more variable than the other results. Our results thus indicate that rivals settle contests following the rules predicted by WOA and E‐WOA in most species. However, we also found inconsistencies between the behaviours exhibited during contests and the assumptions of WOA models in most species. We discuss additional (and relatively untested) theoretical possibilities that may be explored to resolve the existing inconsistencies.     

Ecological genetics of the Bromus tectorum (Poaceae)-Ustilago bullata (Ustilaginaceae) pathosystem: A role for frequency-dependent selection?

? Premise of the study: Evolutionary processes that maintain genetic diversity in plants are likely to include selection imposed by pathogens. Negative frequency-dependent selection is a mechanism for maintenance of resistance polymorphism in plant-pathogen interactions. We explored whether such selection operates in the Bromus tectorum-Ustilago bullata pathosystem. Gene-for-gene relationships between resistance and avirulence loci have been demonstrated for this pathosystem. ? Methods: We used molecular markers and cross-inoculation trials to learn whether the SSR genotypes of the host exhibited resistance to co-occurring pathogen races, whether host genotypes within a population had equal disease probability, and whether a common resistance locus and its corresponding avirulence locus exhibited predicted allele frequency changes during an epidemic. ? Key results: Five of six putative resistance loci that conferred resistance to co-occurring pathogen races occurred in common host SSR genotypes. Some common genotypes within populations were more likely to be diseased than others, and genotype frequencies sometimes changed across years in patterns consistent with frequency-dependent selection. Observed changes in frequency of resistance and virulence alleles during an epidemic provided further support, but evidence was inconclusive. ? Conclusions: Frequency-dependent selection may operate at endemic disease levels in this pathosystem, but is difficult to detect because many susceptible plants escape infection. Most pathogen isolates were virulent on most host genotypes, minimizing the apparent importance of frequency-dependent selection even during epidemics.     

Can sieve-element plastids in Panicum maximum (Poaceae) leaves act in the blockage of injured sieve-tube elements?

The ultrastructural features and the plastid changes caused by sample preparation were studied in sieve elements of Panicum maximum leaves. Samples of expanded leaves, taken near the ligule region, were fixed and processed by common light and transmission electron microscopy methods. In mature sieve-tube elements, the protoplast is electron-translucent and plastids are the most frequent organelles. Mitochondria and smooth endoplasmic reticulum segments are also visible and occupy a parietal position within the cell. The plastids are globular and show electron-dense proteinaceous inclusions in the stroma. The protein crystals are predominantly cuneate, but thin crystalloids and amorphous and/or filamentous proteins also occur. The presence of intact plastids plus others in different phases of plastid envelope rupture were interpreted as evidence that this rupture is a normal event in response to injury. This plastid envelope rupture is possibly activated by the release of pressure in the sieve-tube element. After plastid membrane vesiculation, the stroma and the protein crystals are dispersed within the sieve-element ground cytoplasm. The vesicles originating from the plastid envelope move to one cell pole, while protein crystalloids move to the opposite pole and agglomerate in the sieve-plate region. Our findings indicate that these protein crystalloids, which deposit in the sieve plate, may act in sieve-plate pores occlusion, preventing the release of phloem sap, similar to the role of P-protein in dicotyledons.     

Accumulation of phenanthrene by roots of intact wheat (<Emphasis Type="Italic">Triticum acstivnm</Emphasis>L.) seedlings: passive or active uptake?

Background  

Polycyclic aromatic hydrocarbons (PAHs) are of particular concern due to their hydrophobic, recalcitrant, persistent, potentially carcinogenic, mutagenic and toxic properties, and their ubiquitous occurrence in the environment. Most of the PAHs in the environment are present in surface soil. Plants grown in PAH-contaminated soils or water can become contaminated with PAHs because of their uptake. Therefore, they may threaten human and animal health. However, the mechanism for PAHs uptake by crop roots is little understood. It is important to understand exactly how PAHs are transported into the plant root system and into the human food chain, since it is beneficial in governing crop contamination by PAHs, remedying soils or waters polluted by PAHs with plants, and modeling potential uptake for risk assessment.