Phylogenetic affiliation of the desert truffles <Emphasis Type="Italic">Picoa juniperi</Emphasis> and <Emphasis Type="Italic">Picoa lefebvrei</Emphasis>

The molecular phylogeny and comparative morphological studies reported here provide evidence for the recognition of the genus Picoa, an hypogeous desert truffle, in the family Pyronemataceae (Ascomycota, Pezizales). Picoa juniperi and Picoa lefebvrei were reassigned to the genus Picoa based on large subunit (LSU) sequence (28S) rDNA and internal transcribed spacer (ITS) rDNA (including the partial 18S, ITS1, ITS2, 5.8S gene, and partial 28S of the nuclear rDNA) data. Morphological studies of spores, asci, perida, and gleba revealed high similarities between P. lefebvrei and P. juniperi, thereby confirming the membership of both species in the genus Picoa. These two species were primarily distinguishable based on ascospore ornamentation.     

Occurrence and diversity of Frankia in Tunisian soil

There is a lack of studies on the occurrence and diversity of Frankia in African soils, including those in northern African regions. The present study on Tunisian soils is an attempt to address this issue using Alnus glutinosa , Elaeagnus angustifolia and Casuarina glauca in a plant capturing bioassay on 30 soil samples, followed by amplified 16S ribosomal DNA restriction pattern analysis (ARDRA). A total of seven ARDRA haplotypes of Frankia have been detected in root actinorhizas that have been affiliated to theoretical ARDRA haplotypes upon in silico digestion of selected 16S ribosomal RNA (rRNA) gene sequences retrieved from GeneBank and confirmed by their partial 16S rRNA gene sequencing. Elaeagnus -compatible Frankia isolates were widespread and form four ARDRA haplotypes affiliated to Frankia , colonizing Elaeagnaceae and Rhamnaceae in two different phylogenetic subgroups. Alnus -compatible strains occurring in northern subhumid area were closely related to Alnus – Morella -compatible strains and clustered in two ARDRA haplotypes. Casuarina -compatible strains lack variability in several northern arboreta. The relatively wide diversity of Tunisian Frankia strains opens the perspective that African soil could be an interesting reservoir for the isolation of new actinorhizal strains that could be used as potential biofertilizers to counteract the progressive soil desertification which indeed is a crucial environmental problem in Northern Africa.     

Assessment of genetic diversity of Mediterranean bread wheat using Randomly Amplified Polymorphic DNA (RAPD) markers

The genetic diversity of 14 bread wheat (Triticum aestivum L.) varieties originating from Mediterranean region (Egypt and Greece) was assessed by means of Randomly Amplified Polymorphic DNA (RAPD) markers. Seventeen RAPD markers were used to analyze and compare genetic diversity among the selected wheat varieties. Average of similarity coefficients based on RAPD markers for all of the studied varieties was 0.718. Average and range of genetic similarity coefficients among varieties obtained from both Egypt and Greece independently were 0.765 (from 0.66 to 0.886) and 0.723 (from 0.604 to 0.896), respectively. The cophenetic correlation coefficients of the three RAPD dendrograms (generated for all of the 14 varieties, the seven Egyptian varieties separately and the seven Greek varieties separately) were r = 0.774, 0.80, and 0.74, respectively. Both cluster analysis and Principal Coordinate Analysis (PCOORDA) were able to differentiate between Egyptian and Greek wheat varieties, but PCOORDA was more efficient in its separation. The percentage of variance accounted for the first two principal coordinates was 49.45% of total genetic variance for RAPD. Notable geographical divergence was found between Egyptian and Greek wheat varieties.     

Structure and bioassessment of benthic communities of a lagoonal ecosystem of the Atlantic Moroccan coast

The Merja Zerga lagoon is a semi-enclosed marine ecosystem in which various types of human activities have been developed. This paper characterizes the biosedimentary units of the lagoon and defines a reference status of the quality and health of the macrozoobenthic communities that can be used as bioindicators of the quality of the global marine environment. Specific and functional diversity were high: 147 taxa were identified; they were distributed within seven main trophic groups. Trophic structure is dominated by the suspension-feeding bivalve Cerastoderma edule and the deposit-feeding bivalve Scrobicularia plana, while micrograzers and macroherbivores remain low. Biotic index values indicated that the site is moderately perturbed and that the benthic communities are unbalanced. Nevertheless, the communities showed a seasonal stability of abundances and a high specific richness all through the year.     

Allelic structure and distribution of 103 STR loci in a Southern Tunisian population

Genotypes of 103 short tandem repeat (STR) markers distributed at an average of 40 cM intervals throughout the genome were determined for 40 individuals from the village of BirEl Hfai (BEH). This village of approximately 31.000 individuals is localized in the south-west of Tunisia. The allele frequency distributions in BEH were compared with those obtained for individuals in the CEPH (Centre d’Etude du Polymorphisme Humain) data using a Kolmo-gorov-Smirnov two-sample test. Fourteen out of the 103 markers (13.2%) showed significant differences (P<0.05) in distribution between the two populations. Population heterogeneity in BEH was indicated by an excess of observed homozygosity deviations from Hardy-Weinberg equilibrium at 3 loci (P<0.0005). No evidence for genotypic disequilibrium was found for any of the marker pairs. This demonstrated that in spite of a high inbreeding level in the population, few markers showed evidence for a different pattern of allelic distribution compared to CEPH.     

MicroRNA-21 Is a Downstream Effector of AKT That Mediates Its Antiapoptotic Effects via Suppression of Fas Ligand

MicroRNA-21 (miR-21) is highly up-regulated during hypertrophic and cancerous cell growth. In contrast, we found that it declines in cardiac myocytes upon exposure to hypoxia. Thus, the objective was to explore its role during hypoxia. We show that miR-21 not only regulates phosphatase and tensin homologue deleted on chromosome 10 (PTEN), but also targets Fas ligand (FasL). During prolonged hypoxia, down-regulation of miR-21 proved necessary and sufficient for enhancing expression of both proteins. We demonstrate here for the first time that miR-21 is positively regulated via an AKT-dependent pathway, which is depressed during prolonged hypoxia. Accordingly, hypoxia-induced down-regulation of miR-21 and up-regulation of FasL and PTEN were reversed by activated AKT and reproduced by a dominant negative mutant, wortmannin, or PTEN. Moreover, the antiapoptotic function of AKT partly required miR-21, which was sufficient for inhibition of caspase-8 activity and mitochondrial damage. In consensus, overexpression of miR-21 in a transgenic mouse heart resulted in suppression of ischemia-induced up-regulation of PTEN and FasL expression, an increase in phospho-AKT, a smaller infarct size, and ameliorated heart failure. Thus, we have identified a unique aspect of the function of AKT by which it inhibits apoptosis through miR-21-dependent suppression of FasL.     

Oriented immobilization of the tobacco etch virus protease for the cleavage of fusion proteins

The tobacco etch virus (TEV) protease is a useful tool for the removal of fusion tags from recombinant proteins. The difficulty in obtaining this enzyme led us to look for an optimal method for its use. In this work, we produced both the wild-type and the S219V mutant TEV proteases fused to the Streptag II affinity sequence (Streptag II-TEV(WT), and Streptag II-TEV(S219V), respectively). The two enzymes were affinity immobilized on a streptavidin-agarose matrix and compared to their respective free forms. Both immobilized Streptag II-TEV(WT) and Streptag II-TEV(S219V) were active on the 74-kDa Streptag II substrate with a retained activity of 83.5% and 81%, respectively compared to their free corresponding forms. The slight enzyme activity decrease caused by the immobilization was balanced by the enhanced stability and the successful repetitive use of the proteolytic columns. Thus, the wild-type and the mutant immobilized proteases were used, during a period of 18 months, for nine batch reactions with retention of 38% and 51% of their initial activities, respectively. The present results demonstrate that immobilized TEV protease on streptavidin-agarose is an attractive and efficient tool for fusion protein cleavage, especially when the target protein is fused to a streptagged fusion partner. Using this strategy, the total process can be shortened by performing the cleavage and the recovery of the purified target protein in one step.