SF2/ASF regulates proteomic diversity by affecting the balance between translation initiation mechanisms

Post‐splicing activities have been described for a subset of shuttling serine/arginine‐rich splicing regulatory proteins, among them SF2/ASF. We showed that growth factors activate a Ras‐PI 3‐kinase‐Akt/PKB signaling pathway that not only modifies alternative splicing of the fibronectin EDA exon, but also alters in vivo translation of reporter mRNAs containing the EDA binding motif for SF2/ASF, providing two co‐regulated levels of isoform‐specific amplification. Translation of most eukaryotic mRNAs is initiated via the scanning mechanism, which implicates recognition of the m7G cap at the mRNA 5′‐terminus by the eIF4F protein complex. Several viral and cellular mRNAs are translated in a cap‐independent manner by the action of cis‐acting mRNA elements named internal ribosome entry sites that direct internal ribosome binding to the mRNA. Here we use bicistronic reporters that generate mRNAs carrying two open reading frames, one translated in a cap‐dependent manner while the other by internal ribosome entry site‐dependent initiation, to show that in vivo over‐expression of SF2/ASF increases the ratio between cap‐dependent and internal ribosome entry site‐dependent translation. Consistently, knocking‐down of SF2/ASF causes the opposite effect. Changes in expression levels of SF2/ASF also affect alternative translation of an endogenous mRNA, that one coding for fibroblast growth factor‐2. These results strongly suggest a role for SF2/ASF as a regulator of alternative translation, meaning the generation of different proteins by the balance among these two translation initiation mechanisms, and expand the known potential of SF2/ASF to regulate proteomic diversity to the translation field. J. Cell. Biochem. 107: 826–833, 2009. © 2009 Wiley‐Liss, Inc.     

Lack of evidence for meteorological effects on infradian dynamics of testosterone

Climatic factors are known to influence the endocrine system. Previous studies have shown that circannual seasonal variations of testosterone might be partly explained by changes in air temperature. Whether infradian variations are affected by meteorological factors is unknown. To analyze possible effects of meteorological parameters on infradian variations of salivary testosterone levels in both sexes, daily salivary testosterone levels were measured during 1 month in 14 men and 17 women. A correlation analysis between hormonal levels and selected meteorological parameters was performed. The results indicate that high testosterone levels are loosely associated with cold, sunny and dry weather in both sexes. However, only the correlations between testosterone and air temperature (men) and actual cloudiness (women) were statistically significant (p < 0,05). Although some correlations reached the level of statistical significance, the effects of selected meteorological parameters on salivary testosterone levels remain unclear. Further longer-term studies concentrating on air temperature, cloudiness and average relative humidity in relation to the sex hormone axis are needed.     

Increasing incidence of Geomyces destructans fungus in bats from the Czech Republic and Slovakia

Background

White-nose syndrome is a disease of hibernating insectivorous bats associated with the fungus Geomyces destructans. It first appeared in North America in 2006, where over a million bats died since then. In Europe, G. destructans was first identified in France in 2009. Its distribution, infection dynamics, and effects on hibernating bats in Europe are largely unknown.

Methodology/Principal Findings

We screened hibernacula in the Czech Republic and Slovakia for the presence of the fungus during the winter seasons of 2008/2009 and 2009/2010. In winter 2009/2010, we found infected bats in 76 out of 98 surveyed sites, in which the majority had been previously negative. A photographic record of over 6000 hibernating bats, taken since 1994, revealed bats with fungal growths since 1995; however, the incidence of such bats increased in Myotis myotis from 2% in 2007 to 14% by 2010. Microscopic, cultivation and molecular genetic evaluations confirmed the identity of the recently sampled fungus as G. destructans, and demonstrated its continuous distribution in the studied area. At the end of the hibernation season we recorded pathologic changes in the skin of the affected bats, from which the fungus was isolated. We registered no mass mortality caused by the fungus, and the recorded population decline in the last two years of the most affected species, M. myotis, is within the population trend prediction interval.

Conclusions/Significance

G. destructans was found to be widespread in the Czech Republic and Slovakia, with an epizootic incidence in bats during the most recent years. Further development of the situation urgently requires a detailed pan-European monitoring scheme.     

A synthetic glycopeptide of human myelin oligodendrocyte glycoprotein to detect antibody responses in multiple sclerosis and other neurological diseases

Glycopeptides of hMOG(30-50) containing a glucosyl moiety on the side-chains of Asn, Ser or Hyp at position 31 were synthesised. Antibody titres to hMOG(30-50) and to its glucoderivatives were measured by ELISA in sera of patients affected by different neurological diseases. Anti-hMOG(30-50) antibodies were detected only using the glycopeptide [Asn31(N-Glc)]hMOG(30-50).     

Contrasting growth forecasts across the geographical range of Scots pine due to altitudinal and latitudinal differences in climatic sensitivity

Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of a species’ geographical distribution, where differences in growth or population dynamics may result in range expansions or contractions. Understanding population responses to different climatic drivers along wide latitudinal and altitudinal gradients is necessary in order to gain a better understanding of plant responses to ongoing increases in global temperature and drought severity. We selected Scots pine (Pinus sylvestris L.) as a model species to explore growth responses to climatic variability (seasonal temperature and precipitation) over the last century through dendrochronological methods. We developed linear models based on age, climate and previous growth to forecast growth trends up to year 2100 using climatic predictions. Populations were located at the treeline across a latitudinal gradient covering the northern, central and southernmost populations and across an altitudinal gradient at the southern edge of the distribution (treeline, medium and lower elevations). Radial growth was maximal at medium altitude and treeline of the southernmost populations. Temperature was the main factor controlling growth variability along the gradients, although the timing and strength of climatic variables affecting growth shifted with latitude and altitude. Predictive models forecast a general increase in Scots pine growth at treeline across the latitudinal distribution, with southern populations increasing growth up to year 2050, when it stabilizes. The highest responsiveness appeared at central latitude, and moderate growth increase is projected at the northern limit. Contrastingly, the model forecasted growth declines at lowland‐southern populations, suggesting an upslope range displacement over the coming decades. Our results give insight into the geographical responses of tree species to climate change and demonstrate the importance of incorporating biogeographical variability into predictive models for an accurate prediction of species dynamics as climate changes.     

Phosphatidyl choline fatty acid remodeling in the hepatic cell nuclei

This study was performed to determine whether fatty acids incorporated into liver cell nuclei phosphatidylcholine (PtdCho) could be remodeled in the isolated nuclear. For this reason, rat liver cell nuclei were incubated in vitro with [1-14C]20:4n-6-CoA. PtdCho molecular species with the highest specific activity had an unsaturated fatty acid at sn-1 and sn-2 positions (20:4-20:4>18:2-20:4>18:1-20:4). 16:0-20:4 and 18:0-20:4 PtdChos showed a minor specific activity. When labeled nuclei were reincubated in the absence of labeled substrate with the addition of cytosol, ATP and CoA, the specific activity of 20:4-20:4, 18:2-20:4 and 18:1-20:4 species decreased, while that of 16:0-20:4 and 18:0-20:4 increased. In conclusion, the asymmetric fatty acid distribution of saturated fatty acids at sn-1 position, and unsaturated fatty acids at sn-2 position of nuclear PtdCho molecular species was re-established by an acyl-CoA-dependent remodeling process.     

Marine flooding event in continental Triassic facies identified by a nothosaur and placodont bonebed (South Iberian Paleomargin)

Sudden marine flooding within otherwise continental successions of the Triassic is unusual. The Tabular Cover of the SE paleomargin of the Iberian Massif is characterized by continental Triassic redbed facies composed of sandstones and siltstones, with gypsum-rich levels in the transition to Jurassic limestones. These Triassic deposits were developed in a fluvial-coastal system and they are 300 m thick in the Puente Génave-Villarrodrigo area, eastern Jaén Province, Spain. An unexpected sandstone-limestone unit in the lower part of this formation, recognized over more than 30 km, contains marine reptile bones in a storm bed or tsunami deposit. The lower part of this unit is characterized by a sandstone with sedimentary structures indicative of high-energy conditions as well as by fossil remains of marine reptiles. This bed ranges from 0 to 90 cm in thickness, and in some outcrops pinches out rapidly within a few meters. The upper part of the studied unit is a limestone with common trace fossils and abundant remains of marine reptiles, comprising isolated and fragmented pieces of sauropterygians (nothosaurs, pachypleurosaurs, and placodonts). Most abundant are vertebrae and ribs. In some outcrops, the top of this bed presents a dense accumulation of well-preserved small gastropods. The limestone is overlain by red siltstones and sandstones. The studied unit is interpreted as a marine deposit representing a high-energy event and records exceptional marine flooding in a distal fluvial environment, in fact the only open-marine deposit in the Villarrodrigo section. The sedimentary structures in the lower part of the unit are typical of high-energy deposits and indicate deposition in a single episode, probably related to a storm surge or a tsunami. The fragmentation, disarticulation, and dispersion of the vertebrate bones and the imbrication of bioclasts are consistent with a high-energy event that favored the concentration of bones according to size and density.     

A comparative genomic analysis of the alkalitolerant soil bacterium Bacillus lehensis G1

Bacillus lehensis G1 is a Gram-positive, moderately alkalitolerant bacterium isolated from soil samples. B. lehensis produces cyclodextrin glucanotransferase (CGTase), an enzyme that has enabled the extensive use of cyclodextrin in foodstuffs, chemicals, and pharmaceuticals. The genome sequence of B. lehensis G1 consists of a single circular 3.99 Mb chromosome containing 4017 protein-coding sequences (CDSs), of which 2818 (70.15%) have assigned biological roles, 936 (23.30%) have conserved domains with unknown functions, and 263 (6.55%) have no match with any protein database. Bacillus clausii KSM-K16 was established as the closest relative to B. lehensis G1 based on gene content similarity and 16S rRNA phylogenetic analysis. A total of 2820 proteins from B. lehensis G1 were found to have orthologues in B. clausii, including sodium–proton antiporters, transport proteins, and proteins involved in ATP synthesis. A comparative analysis of these proteins and those in B. clausii and other alkaliphilic Bacillus species was carried out to investigate their contributions towards the alkalitolerance of the microorganism. The similarities and differences in alkalitolerance-related genes among alkalitolerant/alkaliphilic Bacillus species highlight the complex mechanism of pH homeostasis. The B. lehensis G1 genome was also mined for proteins and enzymes with potential viability for industrial and commercial purposes.     

Chromosome studies in southern species of Mimosa (Fabaceae,Mimosoideae) and their taxonomic and evolutionary inferences

In this work, chromosome numbers and karyotype parameters of 36 taxa of the genus Mimosa were studied, especially from the southern South America center of diversification. Results support that x = 13 is the basic chromosome number in the genus. Polyploidy is very frequent, ca. 56 % of the total of the studied species here are polyploid, confirming that polyploids are more frequent at higher latitudes. The most common ploidy levels found are 2x and 4x, but some species studied exhibit 6x and 8x. In different groups, several ploidy levels were found. Parameters of chromosome size show statistically significant differences between close species, and asymmetry index A ₂ exhibited low variation between them. It is possible to infer variations of chromosome size between diploids and tetraploids and between basal and derived taxa. The present studies confirm or reveal polyploidy in several groups of South America which are highly diversified in the southernmost area of distribution of the genus, such as sect. Batocaulon ser. Stipellares and sect. Calothamnos. Our data are discussed in a taxonomic context, making inferences about the origin of some polyploid taxa. Polyploidy could be an important phenomenon that increases the morphologic diversity and specific richness in southern South America. On basis of our data, it is possible to hypothesize hybridization between same-ploidy level or different ploidy level taxa. As already shown in the literature, our results confirm the importance of the polyploidy in the speciation of the genus.