Predicting changes in Fennoscandian vascular-plant species richness as a result of future climatic change

It is anticipated that future climatic warming following the currently enhanced greenhouse effect will change the distribution limits of many vascular plant species. Using annual accumulated respiration equivalents, calculated from January and July mean temperatures and total annual precipitation, simple presence–absence response surface plots are constructed for 1521 native vascular-plant species in 229 75×75-km grid squares within Fennoscandia. The contemporary occurrences in relation to present-day climate and to predicted changes in climate (and hence annual accumulated respiration equivalents) are used to predict possible future immigrations and extinctions within each grid square. The percentage of potential change in species richness for each grid square is estimated from these predictions. Results from this study suggest a mean increase in species richness per grid square of 26%. Increases in species richness are greatest in the southern parts of the alpine/boreal regions in Fennoscandia. There are ten species that potentially may become extinct in Fennoscandia as a result of predicted climatic warming. Possible conservation strategies to protect such endangered species are outlined.     

Binding proteins for adenosine 3′:5′-cyclic monophosphate in bovine adrenal cortex

Five peaks of cyclic AMP-binding activity could be resolved by DEAE-cellulose chromatography of bovine adrenal-cortex cytosol. Two of the binding peaks co-chromatographed with the catalytic activities of cyclic AMP-dependent protein kinases (ATP-protein phosphotransferase, EC 2.7.1.37) of type I or type II respectively. A third binding protein was eluted between the two kinases, and appeared to be the free regulatory moiety of protein kinase I. Two of the binding proteins for cyclic AMP, sedimenting at 9S in sucrose gradients, could also bind adenosine. They bound cyclic AMP with an apparent equilibrium dissociation constant (K(d)) of about 0.1mum, and showed an increased binding capacity for cyclic AMP after preincubation in the presence of K(+), Mg(2+) and ATP. The two binding proteins differed in their apparent affinities for adenosine. The isolated regulatory moiety of protein kinase I had a very high affinity for cyclic AMP (K(d)<0.1nm). At low ionic strength or in the presence of MgATP, the high-affinity binding of cyclic AMP to the regulatory subunit of protein kinase I was decreased by the catalytic subunit. At high ionic strength and in the absence of MgATP the high-affinity binding to the regulatory subunit was not affected by the presence of catalytic subunit. Under all experimental conditions tested, dissociation of protein kinase I was accompanied by an increased affinity for cyclic AMP. To gain some insight into the mechanism by which cyclic AMP activates protein kinase, the interaction between basic proteins, salt and the cyclic nucleotide in activating the kinase was studied.     

Inference of genetic architecture from chromosome partitioning analyses is sensitive to genome variation,sample size,heritability and effect size distribution

Genomewide association studies have contributed immensely to our understanding of the genetic basis of complex traits. One major conclusion arising from these studies is that most traits are controlled by many loci of small effect, confirming the infinitesimal model of quantitative genetics. A popular approach to test for polygenic architecture involves so‐called “chromosome partitioning” where phenotypic variance explained by each chromosome is regressed on the size of the chromosome. First developed for humans, this has now been repeatedly used in other species, but there has been no evaluation of the suitability of this method in species that can differ in their genome characteristics such as number and size of chromosomes. Nor has the influence of sample size, heritability of the trait, effect size distribution of loci controlling the trait or the physical distribution of the causal loci in the genome been examined. Using simulated data, we show that these characteristics have major influence on the inferences of the genetic architecture of traits we can infer using chromosome partitioning analyses. In particular, small variation in chromosome size, small sample size, low heritability, a skewed effect size distribution and clustering of loci can lead to a loss of power and consequently altered inference from chromosome partitioning analyses. Future studies employing this approach need to consider and derive an appropriate null model for their study system, taking these parameters into consideration. Our simulation results can provide some guidelines on these matters, but further studies examining a broader parameter space are needed.     

Interdomain salt‐bridges in the Ebola virus protein VP40 and their role in domain association and plasma membrane localization

The Ebola virus protein VP40 is a transformer protein that possesses an extraordinary ability to accomplish multiple functions by transforming into various oligomeric conformations. The disengagement of the C‐terminal domain (CTD) from the N‐terminal domain (NTD) is a crucial step in the conformational transformations of VP40 from the dimeric form to the hexameric form or octameric ring structure. Here, we use various molecular dynamics (MD) simulations to investigate the dynamics of the VP40 protein and the roles of interdomain interactions that are important for the domain–domain association and dissociation, and report on experimental results of the behavior of mutant variants of VP40. The MD studies find that various salt‐bridge interactions modulate the VP40 domain dynamics by providing conformational specificity through interdomain interactions. The MD simulations reveal a novel salt‐bridge between D45‐K326 when the CTD participates in a latch‐like interaction with the NTD. The D45‐K326 salt‐bridge interaction is proposed to help domain–domain association, whereas the E76‐K291 interaction is important for stabilizing the closed‐form structure. The effects of the removal of important VP40 salt‐bridges on plasma membrane (PM) localization, VP40 oligomerization, and virus like particle (VLP) budding assays were investigated experimentally by live cell imaging using an EGFP‐tagged VP40 system. It is found that the mutations K291E and D45K show enhanced PM localization but D45K significantly reduced VLP formation.     

Cyclone tolerance in new world arecaceae: biogeographic variation and abiotic natural selection

Background and Aims

Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection.

Methods

New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts.

Key Results

Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0·001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality.

Conclusions

Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas.Key words: Abiotic selection, Arecaceae, biogeography, cyclone, hurricane, phylogenetic independence     

Curcumin treatment prevents increased proteasome and apoptosome activities in rat skeletal muscle during reloading and improves subsequent recovery

Immobilization is characterized by activation of the ubiquitin (Ub)-proteasome-dependent proteolytic system (UPS) and of the mitochondrial apoptotic pathway. Increased oxidative stress and inflammatory response occur in immobilized skeletal muscles. Curcumin exhibits antioxidant and anti-inflammatory properties, blocked proteasome activation in intact animals, and may favor skeletal muscle regeneration. We therefore measured the effects of curcumin on immobilization-induced muscle atrophy and subsequent recovery. Rats were subjected to hindlimb immobilization for 8 days (I8) and allowed to recover for 10 days (R10). Fifty percent of the rats were injected daily with either curcumin or vehicle. Proteolytic and apoptotic pathways were studied in gastrocnemius muscles. Curcumin treatment prevented the enhanced proteasome chymotrypsin-like activity and the trend toward increased caspase-9-associated apoptosome activity at I8 in immobilized muscles. By contrast, the increase of these two activities was blunted by curcumin at R10. Curcumin did not reduce muscle atrophy at I8 but improved muscle recovery at R10 and the cross-sectional area of muscle fibers of immobilized muscles. Curcumin reduced the increased protein levels of Smac/DIABLO induced by immobilization and enhanced the elevation of X-linked inhibitory apoptotic protein levels at R10. Ub-conjugate levels and caspase-3 activity increased at I8 and were normalized at R10 without being affected by curcumin treatment. Altogether, the data show that curcumin treatment improved recovery during reloading. The effect of curcumin during the atrophic phase on proteasome activities may facilitate the initiation of muscle recovery after reloading. These data also suggest that this compound may favor the initial steps of muscle regeneration.     

Effects of fertilization and afforestation on community structure of traditionally managed hay meadows in western Norway

The aims of this paper were to find the effects of artificial fertilizer, intensive cultivation and abandonment with afforestation on species composition of traditional meadows at a broad scale, and to describe the ecological variation of different meadow communities. The flora of 21 traditionally managed hay meadows was compared with that of 52 artificially fertilized hay meadows, 28 intensively cultivated grasslands and 29 afforested grasslands by means of classification. Predictors for differences in species composition were tested using multiple regression analyses with associated Monte Carlo permutation tests. Habitat diversity and Ellenberg N were the most important predictors for differences in species composition of traditional meadows. High habitat diversity was associated with maximum occurrences of all kinds of meadow species (high-productive, generalist, low-productive, habitat specialist, regionally rare, vulnerable and orchid species). These meadows are therefore of high conservation value. Traditional meadows contained also some nitrophilous species that dominate artificially fertilized meadows, but in small populations. Artificially fertilized meadows supported the generalist and productive subset of the species from traditional meadows. Thus, artificially fertilized meadows are of low conservation value. As regionally rare and vulnerable species were only recorded at sites with no use of artificial fertilizer, its application should be avoided whenever the aim is to recreate or maintain semi-natural grasslands of high conservation value. Regionally rare and vulnerable meadow species were not recorded in afforested sites, suggesting that afforestation of traditional meadows may have similar negative effects for the traditional meadow flora as the use of artificial fertilizer.