Community structure of soil oribatida (acari) two years after windthrow in the high tatra mountains

In November 2004 a catastrophic windstorm destroyed a large part of the spruce forest in the Tatra National Park (Slovakia). The majority of the windthrown area was cleared; only a small part was left uncleared, thereby allowing regeneration by natural succession. The aim of the present study was to assess the impact of the different forestry practices on soil Oribatida. Three different stands were selected for the study, where sampling took place in June and October 2006: control forest stands (REF), windthrown stands left for natural development (NEX) and clear-cut windthrown stands (EXT). The mean abundance of Oribatida recorded in REF and NEX stands was significantly higher than in EXT stands. Kruskal-Wallis test of mean abundance of adults as well as juveniles confirmed significant influence of treatment and date. The highest abundance of adults was found in control forest stands (REF). Post hoc multiple comparison proved significantly lower abundance of adults in clear-cut stands (EXT) compared with REF. The mean abundance of adults and juveniles was several times higher in stands left for natural development (NEX) than in EXT stands. The highest species richness was observed in REF, followed by NEX and EXT stands. Ordination method showed differences in species composition between studied treatments. Furthermore, a much lower abundance of Hermannia gibba, a dweller of leaf litter and upper soil layers, was recorded in cleared stands compared to the other stands. Indeed, windthrown stands had an obvious lower species richness than control stands. The ordination method used demonstrated a significant influence of both treatment and sampling date on the abundance and species richness of Oribatida. The present study showed that clear-cutting of wind-damaged spruce forest markedly decreases the abundance of soil Oribatida compared with windthrown forest stands left to natural succession.     

Involvement of the Adhesion GPCRs Latrophilins in the Regulation of Insulin Release

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N5-methyl-tetrahydromethanopterin:coenzyme M methyltransferase of Methanosarcina strain Gö1 is an Na(+)-translocating membrane protein.

To determine the cellular localization of components of the methyltransferase system, we separated cell extracts of Methanosarcina strain G?1 into cytoplasmic and inverted-vesicle fractions. Measurements demonstrated that 83% of the methylene-tetrahydromethanopterin reductase activity resided in the cytoplasm whereas 88% of the methyl-tetrahydromethanopterin:coenzyme M methyltransferase (methyltransferase) was associated with the vesicles. The activity of the methyltransferase was stimulated 4.6-fold by ATP and 10-fold by ATP plus a reducing agent [e.g., Ti(III)]. In addition, methyltransferase activity depended on the presence of Na+ (apparent Km = 0.7 mM) and Na+ was pumped into the lumen of the vesicles in the course of methyl transfer from methyl-tetrahydromethanopterin not only to coenzyme M but also to hydroxycobalamin. Both methyl transfer reactions were inhibited by 1-iodopropane and reconstituted by illumination. A model for the methyl transfer reactions is presented.     

Mnl2, a novel component of the ER associated protein degradation pathway

In eukaryotes, membrane and soluble proteins of the secretory pathway enter the endoplasmic reticulum (ER) after synthesis in an unfolded state. Directly after entry, most proteins are modified with glycans at suitable glycosylation sites and start to fold. A protein that cannot fold properly will be degraded in a process called ER associated degradation (ERAD). Failures in ERAD, either by loss of function or by premature degradation of proteins, are a cause of severe diseases. Therefore, the search for novel ERAD components to gain better insight in this process is of high importance. Carbohydrate trimming is a relevant process in ER quality control. In this work a novel putative yeast mannosidase encoded by the open reading frame YLR057W was identified and named Mnl2. Deletion of MNL2 diminished the degradation efficiency of misfolded CPY^* in the absence of the cognate mannosidase Mnl1, indicating a specific role in ERAD.     

The ITS1-5.8S-ITS2 sequence region in the Musaceae: structure, diversity and use in molecular phylogeny

Genes coding for 45S ribosomal RNA are organized in tandem arrays of up to several thousand copies and contain 18S, 5.8S and 26S rRNA units separated by internal transcribed spacers ITS1 and ITS2. While the rRNA units are evolutionary conserved, ITS show high level of interspecific divergence and have been used frequently in genetic diversity and phylogenetic studies. In this work we report on the structure and diversity of the ITS region in 87 representatives of the family Musaceae. We provide the first detailed information on ITS sequence diversity in the genus Musa and describe the presence of more than one type of ITS sequence within individual species. Both Sanger sequencing of amplified ITS regions and whole genome 454 sequencing lead to similar phylogenetic inferences. We show that it is necessary to identify putative pseudogenic ITS sequences, which may have negative effect on phylogenetic reconstruction at lower taxonomic levels. Phylogenetic reconstruction based on ITS sequence showed that the genus Musa is divided into two distinct clades--Callimusa and Australimusa and Eumusa and Rhodochlamys. Most of the intraspecific banana hybrids analyzed contain conserved parental ITS sequences, indicating incomplete concerted evolution of rDNA loci. Independent evolution of parental rDNA in hybrids enables determination of genomic constitution of hybrids using ITS. The observation of only one type of ITS sequence in some of the presumed interspecific hybrid clones warrants further study to confirm their hybrid origin and to unravel processes leading to evolution of their genomes.     

Carbohydrate uptake in Advenella mimigardefordensis strain DPN7T is mediated by periplasmic sugar oxidation and a TRAP‐transport system

In this study, we investigated an SBP (DctP_Am) of a tripartite ATP‐independent periplasmic transport system (TRAP) in Advenella mimigardefordensis strain DPN7^T. Deletion of dctP_Am as well as of the two transmembrane compounds of the tripartite transporter, dctQ and dctM, impaired growth of A. mimigardefordensis strain DPN7^T, if cultivated on mineral salt medium supplemented with d ‐glucose, d ‐galactose, l ‐arabinose, d ‐fucose, d ‐xylose or d ‐gluconic acid, respectively. The wild type phenotype was restored during complementation studies of A. mimigardefordensis ΔdctP_Am using the broad host vector pBBR1MCS‐5::dctP_Am. Furthermore, an uptake assay with radiolabeled [¹⁴C(U)]‐d ‐glucose clearly showed that the deletion of dctP_Am, dctQ and dctM, respectively, disabled the uptake of this aldoses in cells of either mutant strain. Determination of K_D performing thermal shift assays showed a shift in the melting temperature of DctP_Am in the presence of d ‐gluconic acid (K_D 11.76 ± 1.3 µM) and the corresponding aldonic acids to the above‐mentioned carbohydrates d ‐galactonate (K_D 10.72 ± 1.4 µM), d ‐fuconic acid (K_D 13.50 ± 1.6 µM) and d ‐xylonic acid (K_D 8.44 ± 1.0 µM). The sugar (glucose) dehydrogenase activity (E.C.1.1.5.2) in the membrane fraction was shown for all relevant sugars, proving oxidation of the molecules in the periplasm, prior to transport.     

The effect of aluminum on cytokinins in the mycelia of Amanita muscaria

High performance liquid chromatography analysis of immunoaffinity-purified extracts of mycelia of Amanita muscaria, and the Amaranthus bioassay of the eluted fractions, revealed the following seven cytokinins: zeatin, zeatin riboside, zeatin N-9-glucoside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine, and isopentenyl adenosine. The decreased growth of aluminum-treated mycelia correlated with a 35% decrease in the total amount of the cytokinins. Among individual cytokinins, zeatin was the most affected, exhibiting a reduction of about 90%. The results are compared with previous investigations of aluminum effects on cytokinins in the mycelia of Lactarius piperatus, whose growth is stimulated by aluminum.Abbreviations ZR zeatin riboside - iPA isopentenyl adenosine - Z zeatin - DHZ dihydrozeatin - iP isopentenyl adenine - DHZR dihydrozeatin riboside - Z-9G zeatin N-9-glucoside - iP-9G isopentenyl N-9-glucoside - HPLC high performance liquid chromatography - DHZRMP dihydrozeatin riboside monophosphate - ZRMP zeatin riboside monophosphate     

Patch-Clamp Fluorometry: Electrophysiology meets Fluorescence

Ion channels and transporters are membrane proteins whose functions are driven by conformational changes. Classical biophysical techniques provide insight into either the structure or the function of these proteins, but a full understanding of their behavior requires a correlation of both these aspects in time. Patch-clamp and voltage-clamp fluorometry combine spectroscopic and electrophysiological techniques to simultaneously detect conformational changes and ionic currents across the membrane. Since its introduction, patch-clamp fluorometry has been responsible for invaluable advances in our knowledge of ion channel biophysics. Over the years, the technique has been applied to many different ion channel families to address several biophysical questions with a variety of spectroscopic approaches and electrophysiological configurations. This review illustrates the strength and the flexibility of patch-clamp fluorometry, demonstrating its potential as a tool for future research.     

Intraspecific plant–soil feedback and intraspecific overyielding in Arabidopsis thaliana

Understanding the mechanisms of community coexistence and ecosystem functioning may help to counteract the current biodiversity loss and its potentially harmful consequences. In recent years, plant–soil feedback that can, for example, be caused by below‐ground microorganisms has been suggested to play a role in maintaining plant coexistence and to be a potential driver of the positive relationship between plant diversity and ecosystem functioning. Most of the studies addressing these topics have focused on the species level. However, in addition to interspecific interactions, intraspecific interactions might be important for the structure of natural communities. Here, we examine intraspecific coexistence and intraspecific diversity effects using 10 natural accessions of the model species Arabidopsis thaliana (L.) Heynh. We assessed morphological intraspecific diversity by measuring several above‐ and below‐ground traits. We performed a plant–soil feedback experiment that was based on these trait differences between the accessions in order to determine whether A. thaliana experiences feedback at intraspecific level as a result of trait differences. We also experimentally tested the diversity–productivity relationship at intraspecific level. We found strong differences in above‐ and below‐ground traits between the A. thaliana accessions. Overall, plant–soil feedback occurred at intraspecific level. However, accessions differed in the direction and strength of this feedback: Some accessions grew better on their own soils, some on soils from other accessions. Furthermore, we found positive diversity effects within A. thaliana: Accession mixtures produced a higher total above‐ground biomass than accession monocultures. Differences between accessions in their feedback response could not be explained by morphological traits. Therefore, we suggest that they might have been caused by accession‐specific accumulated soil communities, by root exudates, or by accession‐specific resource use based on genetic differences that are not expressed in morphological traits. Synthesis. Our results provide some of the first evidence for intraspecific plant–soil feedback and intraspecific overyielding. These findings may have wider implications for the maintenance of variation within species and the importance of this variation for ecosystem functioning. Our results highlight the need for an increased focus on intraspecific processes in plant diversity research to fully understand the mechanisms of coexistence and ecosystem functioning.