Type of mycorrhizal associations in two coastal nature reserves of the Mediterranean basin

We analysed the mycorrhizal types of two coastal Mediterranean plant communities. Plants belonging to 82 species of 46 families growing in two Mediterranean study sites located within a Regional Natural Park in Italy (Macchia Lucchese) and in a National Park in Croatia (Brijuni) were assessed for the type of their mycorrhizal associations. Mycorrhizas occurred in 83% and 90% of the plant species surveyed in Macchia Lucchese and in Brijuni, respectively. On the basis of macroscopic and microscopic characteristics, six different mycorrhizal types were found, and their co-occurrence in the same plant community showed the large mycorrhizal diversity in Mediterranean vegetation. Different occurrence patterns of mycorrhizal types have been recognised in diverse habitats within Macchia Lucchese, from sand dune plant communities to sclerophyllous woodland. Mycorrhizal type abundance calculated on a floristic basis was very different from that obtained using a vegetation cover index.     

Nucleoli undergo structural and molecular modifications during hibernation

The nucleolus is a very dynamic structure able rapidly to adapt its activity to the cellular metabolic state. An interesting physiological model characterized by drastic modifications of cellular metabolism is represented by hibernating animals. In the present study we investigated the hepatocyte nuclei of euthermic and hibernating edible dormice (Glis glis) with the aim of revealing, by means of ultrastructural and immunocytochemical analyses, possible modifications of nucleolar components during hibernation. Our observations demonstrate that, in deep hibernation, nucleoli undergo structural and molecular modifications: (a) they show numerous nucleoplasmic invaginations and clumps of dense fibrillar component extend from the nucleolar surface; (b) they are frequently in contact with coiled bodies and fibro-granular material, two nuclear bodies usually occurring in the nucleoplasm; (c) the dense fibrillar component contains significant amounts of small nuclear ribonucleoproteins, splicing factors usually distributed in the nucleoplasm. Taken together, these results suggest that during hibernation complex relationships are established between the nucleolus and nucleoplasm, probably related to functional activities peculiar to this physiological phase. However, since no evident nucleolar modification was found in early hibernating dormice, it seems likely that the particular structural and molecular arrangement of nucleoli establishes progressively during hibernation, becoming evident only in the deepest phase, and then disappears upon arousal.     

Litter in a first–order stream of a temperate deciduous forest (Margaraça Forest, central Portugal)

To evaluate the importance and fate of organic matter inputs in forested streams, we determined the litterfall inputs and the benthic coarse particulate organic matter (CPOM) in one headwater stream flowing through a mixed deciduous forest, during one year. Both vertical traps and the stream bottom were sampled monthly. The material collected was sorted into four main categories: leaves, fruits and flowers, twigs and debris. Litter production was 715 g m−2 y−1 and seasonal, with 73% of the annual total during October–December (autumn). Leaves comprised the largest litter component. Benthic organic matter was 1880 g m−2 y−1, and was also seasonal. Highest accumulation was attained in spring, and twigs and branches comprised the major component. This revised version was published online in July 2006 with corrections to the Cover Date.     

Di-cluster, seven-iron ferredoxins from hyperthermophilic Sulfolobales

 Seven-iron ferredoxins from the thermoacidophilic archaea Acidianus ambivalens, A. infernus, Metalosphaera prunae and Sulfolobus metallicus were extensively characterised, allowing study of their expression under aerobic and anaerobic growth conditions as well as the putative role in thermal stability of a recently described zinc centre. The archaeon S. metallicus was found to express, under the same growth conditions, two ferredoxins in almost identical amounts, a novelty among Archaea. Most interestingly, these two ferredoxins differ at the N-terminal amino acid sequence in that one has a zinc binding motif (FdA) and the other does not (FdB); in agreement with these findings, FdA contains a zinc ion and FdB does not. These two ferredoxins have identical thermal stabilities, indicating that the zinc atom is not determinant in the protein thermostability. Further, the presence of the additional zinc centre does not interfere with the redox properties of the iron-sulfur clusters since their reduction potentials are almost identical. From the other three archaea, independently of the growth mode in respect to oxygen, only a single zinc-containing ferredoxin was found. EPR studies on the purified proteins, both in the oxidised and dithionite reduced states, allowed the identification of one [3Fe-4S]^1+/0 centre and one [4Fe-4S]^2+/1+ centre in all proteins studied. The complete sequence of A. ambivalens ferredoxin is reported. Together with the data gathered in this study, the properties of the seven-iron ferredoxins from Sulfolobales so far known are re-discussed. Received: 10 June 1998 / Accepted: 25 June 1998     

A misfolded protein conformation is not a sufficient condition for in vivo glucosylation by the UDP-Glc:glycoprotein glucosyltransferase.

A key element in the quality control of glycoprotein folding is the UDP-Glc:glycoprotein glucosyltransferase (GT), which in cell-free assays exclusively glucosylates misfolded glycoproteins. In order to test if such a protein conformation is a sufficient condition for in vivo glucosylation of all N-linked oligosaccharides by GT, a Schizosaccharomyces pombe double mutant (gls2/alg6) was constructed. With this mutant, Man9GlcNAc2 is transferred to proteins and no removal of glucose units added by GT occurs as it lacks glucosidase II. The same proportion of glucosylated (Glc1Man9GlcNAc2) and unglucosylated (Man9GlcNAc2 and Man8GlcNAc2) endoplasmic reticulum (ER)-specific compounds was produced when cells were pre-incubated for 10, 20 or 30 min and further incubated with [14C]glucose for 10 min at 28 degrees C with or without 5 mM dithiothreitol (DTT), thus indicating not only that DTT did not affect protein glucosylation but also that no increased glucosylation of glycoproteins occurred in the presence of the drug. Monitoring Golgi-specific modifications of oligosaccharides after pulse-chase experiments performed in the presence or absence of 5 mM DTT showed that exit of the bulk of glycoproteins synthesized from the ER and thence their proper folding had been prevented by the drug. Cells pulse-chase labeled at 37 degrees C in the absence of DTT also yielded glucosylated and unglucosylated protein-linked oligosaccharides without Golgi-specific modifications. It was concluded that a misfolded protein conformation is not a sufficient condition for in vivo glucosylation of all N-linked oligosaccharides by GT.     

Trypanoside,anti-tuberculosis,leishmanicidal, and cytotoxic activities of tetrahydrobenzothienopyrimidines

The synthesis of 2-(5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4-yl)hydrazone-derivatives (BTPs) and their in vitro evaluation against Trypanosoma cruzi trypomastigotes, Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, and six human cancer cell lines is described. The in vivo activity of the most active and least toxic compounds against T. cruzi and L. amazonensis was also studied. BTPs constitute a new family of drug leads with potential activity against infectious diseases. Due to their drug-like properties, this series of compounds can potentially serve as templates for future drug-optimization and drug-development efforts for use as therapeutic agents in developing countries.     

Synthesis,biological evaluation,and SAR study of novel pyrazole analogues as inhibitors of Mycobacterium tuberculosis: Part 2. Synthesis of rigid pyrazolones

Two series of novel rigid pyrazolone derivatives were synthesized and evaluated as inhibitors of Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis. Two of these compounds showed a high activity against MTB (MIC = 4 μg/mL). The newly synthesized pyrazolones were also computationally investigated to analyze if their properties fit the pharmacophoric model for antitubercular compounds previously built by us. The results are in agreement with those reported by us previously for a class of pyrazole analogues and confirm the fundamental role of the p-chlorophenyl moiety at C4 in the antimycobacterial activity.     

Comment on M. Guillot‐Delost et al. (2008;10:834‐846): Clinical‐grade preparation of human natural regulatory T cells encoding the thymidine kinase suicide gene as a safety gene

This Letter to the Editor has a published Response, which can be viewed using the link below. Response to Comment     

Polyploidisation and Geographic Differentiation Drive Diversification in a European High Mountain Plant Group (Doronicum clusii Aggregate,Asteraceae)

Range shifts (especially during the Pleistocene), polyploidisation and hybridization are major factors affecting high-mountain biodiversity. A good system to study their role in the European high mountains is the Doronicum clusii aggregate (Asteraceae), whose four taxa (D. clusii s.s., D. stiriacum, D. glaciale subsp. glaciale and D. glaciale subsp. calcareum) are differentiated geographically, ecologically (basiphilous versus silicicolous) and/or via their ploidy levels (diploid versus tetraploid). Here, we use DNA sequences (three plastid and one nuclear spacer) and AFLP fingerprinting data generated for 58 populations to infer phylogenetic relationships, origin of polyploids—whose ploidy level was confirmed by chromosomally calibrated DNA ploidy level estimates—and phylogeographic history. Taxonomic conclusions were informed, among others, by a Gaussian clustering method for species delimitation using dominant multilocus data. Based on molecular data we identified three lineages: (i) silicicolous diploid D. clusii s.s. in the Alps, (ii) silicicolous tetraploid D. stiriacum in the eastern Alps (outside the range of D. clusii s.s.) and the Carpathians and (iii) the basiphilous diploids D. glaciale subsp. glaciale (eastern Alps) and D. glaciale subsp. calcareum (northeastern Alps); each taxon was identified as distinct by the Gaussian clustering, but the separation of D. glaciale subsp. calcareum and D. glaciale subsp. glaciale was not stable, supporting their taxonomic treatment as subspecies. Carpathian and Alpine populations of D. stiriacum were genetically differentiated suggesting phases of vicariance, probably during the Pleistocene. The origin (autopolyploid versus allopolyploid) of D. stiriacum remained unclear. Doronicum glaciale subsp. calcareum was genetically and morphologically weakly separated from D. glaciale subsp. glaciale but exhibited significantly higher genetic diversity and rarity. This suggests that the more widespread D. glaciale subsp. glaciale originated from D. glaciale subsp. calcareum, which is restricted to a prominent Pleistocene refugium previously identified in other alpine plant species.