Salt tolerance analysis of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> NOK2 accession under saline conditions and potassium supply

The response to salt treatment and K⁺ provision of two Arabidopsis thaliana accessions grown for 17 days in the presence of 50 mM NaCl was investigated. Leaf and root dry weight deposition was restricted by salt, more in Col accession than in NOK2 accession. In both accessions, the growth inhibition induced by salinity was associated with a decrease in total leaf surface area, which resulted from diminished leaf number, but not from restriction of individual leaf surface area. Comparing the effects of salt on dry matter production and total leaf surface area revealed large difference between Col and NOK2 for net assimilation rate (the amount of whole plant biomass produced per unit leaf surface area), which was augmented by salt and K⁺ in NOK2 but not in Col. This result, which suggested a better capacity of NOK2 to preserve its photosynthetic machinery against salt stress, was in agreement with the effect of NaCl on photosynthetic pigments. Indeed, salt significantly reduced chlorophyll and carotenoid content in Col leaves but had no impact on NOK2 leaf pigment content. Since K⁺ provision had only marginal effects on these responses to salt stress, leaf mineral unbalance was unlikely. Guaiacol peroxidase activity was augmented by salt treatment in leaves and roots of both accessions. Salinity decreased the catalase activity in Col leaves and in roots, and increased this activity in NOK2 organs. In conclusion, when aggressed by salt, NOK2 was able (1) to produce more leaves than Col, and (2) to efficiently protect its photosynthetic apparatus, perhaps by developing more efficient antioxidative defense through increased catalase and peroxidase activities. Consequently, the overall photosynthetic activity was higher and more robust to salt aggression in NOK2 than in Col.     

Analysis of Genetic Diversity and Relationships in a Tunisian Fig （Ficus carica） Germplasm Collection by Random Amplified Microsatellite Polymorphisms

The random amplified mirosatellite polymorphism method was performed in a set of Tunisian fig landraces using eighteen primer combinations. A total of sixty three random amplified microsatellite polymorphism （RAMPO） markers were scored and used either to assess the genetic diversity in these cultivars or to detect cases of mislabeling. Opportunely, data proved that the designed procedure constitutes an attractive and fast method with low costs and prevents radio exposure. As a result, we have identified the primer combinations that are the most efficient to detect genetic polymorphism in this crop. Therefore, the derived unweighted pair-group method with arithmetic averages （UPGMA） dendrogram illustrates the genetic divergence among the landraces studied and exhibits a typically continuous variation. Moreover, no evident correlation between the sexes of trees was observed. In addition, using these markers, discrimination between landraces has been achieved. Thus, random amplified mirosatellite polymor- phism is proved to be powerful for characterizing the local fig germplasm.     

Municipal solid waste compost dose effects on soil microbial biomass determined by chloroform fumigation-extraction and DNA methods

We evaluated the relationship between microbial biomass C and N (B_C and B_N) as estimated by the chloroform fumigation-extraction (CFE) method and microbial biomass DNA concentration in a loam-clayey wheat cultivated soil. The soil received municipal solid waste compost at rates of 40 or 80 t ha^?1 and farmyard manure at 40 t ha^?1. Microbial biomasses C and N and DNA concentration centration showed the highest values for microorganisms counts with compost and farmyard manure at 40 t ha^?1. Compost applications at 40 t ha?1 improve the micro-organisms growth than that of 80 t ha^?1. Moreover a significant decrease of soil microbial biomass was noted after fertilisation for three years. The presence of humic acid and proteins impurities in DNA extracts; even in important level as in F-treated soil; did not affect the microbial biomass. The decrease of microbial biomass was due to heavy metals content elevation in compost at 80 t ha^?1 treated soil. Thus the highest rate of municipal solid waste compost induced the lowest ratio of biomass C to soil organic carbon and the lowest ratio of biomass N to soil organic nitrogen. There was a positive relationship between B_C, B_N and DNA concentration. DNA concentration was significantly and positively correlated with B_C and with B_N. However there was a negative correlation between either micro-organisms numbers and DNA concentration, or B_C and B_N. The comparison of the two used methods DNA extraction and CFE showed the lowest coefficient of variation (cv %) with DNA extraction method. This last method can be used as an alternative method to measure the microbial biomass in amended soils.     

Identification of winter moth (Operophtera brumata) refugia in North Africa and the Italian Peninsula during the last glacial maximum

Numerous studies have shown that the genetic diversity of species inhabiting temperate regions has been shaped by changes in their distributions during the Quaternary climatic oscillations. For some species, the genetic distinctness of isolated populations is maintained during secondary contact, while for others, admixture is frequently observed. For the winter moth (Operophtera brumata), an important defoliator of oak forests across Europe and northern Africa, we previously determined that contemporary populations correspond to genetic diversity obtained during the last glacial maximum (LGM) through the use of refugia in the Iberian and Aegean peninsulas, and to a lesser extent the Caucasus region. Missing from this sampling were populations from the Italian peninsula and from North Africa, both regions known to have played important roles as glacial refugia for other species. Therefore, we genotyped field‐collected winter moth individuals from southern Italy and northwestern Tunisia—the latter a region where severe oak forest defoliation by winter moth has recently been reported—using polymorphic microsatellite. We reconstructed the genetic relationships of these populations in comparison to moths previously sampled from the Iberian and Aegean peninsulas, the Caucasus region, and western Europe using genetic distance, Bayesian clustering, and approximate Bayesian computation (ABC) methods. Our results indicate that both the southern Italian and the Tunisian populations are genetically distinct from other sampled populations, and likely originated in their respective refugium during the LGM after diverging from a population that eventually settled in the Iberian refugium. These suggest that winter moth populations persisted in at least five Mediterranean LGM refugia. Finally, we comment that outbreaks by winter moth in northwestern Tunisia are not the result of a recent introduction of a nonnative species, but rather are most likely due to land use or environmental changes.     

Environmental <Emphasis Type="Italic">Burkholderia cepacia</Emphasis> Strain Cs5 Acting by Two Analogous Alkyl-Quinolones and a Didecyl-Phthalate Against a Broad Spectrum of Phytopathogens Fungi

An environmental Burkholderia cepacia strain named Cs5 was isolated and identified first using API biochemical identification system and then with 16S rDNA and recA sequence homology search. This bacterium exhibited a broad spectrum of fungicidal activities against Alternaria alternata, Aspergillus niger, Fusarium culmorum, F. graminearum, F. oxysporum and Rhizoctonia solani. In the liquid conditions, the MIC of A. niger and R. solani were reached with, respectively, 1.25–2% of the Cs5 liquid culture supernatant. However, in the solid conditions, the same inhibition was caused in the presence of 3% of the Cs5 supernatant. The exhibition of these two fungi at low concentrations of supernatant Cs5 caused various morphological changes of their mycelia which were observed by confocal microscopy. Three antifungal compounds, named Cs5-255, Cs5-257 and Cs5-446, were purified from the Cs5 culture. The structural analysis of these molecules showed that Cs5-255 and Cs5-257 are analogous and belonged to the alkyl-quinolone family, while Cs5-446 was a didecyl-phthalate, isolated for the first time from a bacterium.     

Managing the risk of cancer in Cowden syndrome: a case report

ABSTRACT: INTRODUCTION: Cowden syndrome is a rare cancer predisposition syndrome inherited in an autosomaldominantfashion. The syndrome is characterized by hamartomatous polyps that affectmultiple organs: skin, mucous membranes, thyroid, breast, gastrointestinal tract,endometrium and brain. It is also associated with an increased risk of developing malignancyin many tissues but especially breast, thyroid and endometrium. CASE PRESENTATION: We present the case of a 30-year-old Tunisian woman with mental retardation who presentedto our facility with rectal hamartomatous polyps. Her medical history included fibrocysticdisease of the breast over the last three years. A physical examination revealed macrocephaly,hyperkeratotic papules on the mid-facial skin, palmoplantar keratosis and oral mucosalpapillomatosis. A breast examination revealed nodular breast tissue bilaterally and a diffusethyroid goiter. Our patient was clinically euthyroid. A total thyroidectomy was performed. Ahistopathologic examination revealed thyroid papillary carcinoma. A gastrointestinalevaluation revealed esophageal and gastric polyps. Biopsies showed hyperplastic andadenomatous lesions associated with Helicobacter pylori. A final diagnosis of Cowdensyndrome was made according to the syndrome testing criteria adapted by the US NationalComprehensive Cancer Network. A prophylactic bilateral mastectomy was proposed butrefused by our patient. Our patient was kept under surveillance for breast and colorectalmalignancies. CONCLUSIONS: Early and accurate diagnosis of Cowden syndrome is essential because it is a cancerpredisposition syndrome that carries an increased risk for developing malignancy in manytissues, especially breast and thyroid. For this reason, education regarding the signs andsymptoms of cancer is important. All patients must be screened for malignancies and optionsfor prophylactic mastectomy should be discussed. Guidelines for cancer screening includingsurveillance and management plans for these patients should be distinguished from those ofthe general population, and may lead to a more timely diagnosis and treatment of cancersassociated with this syndrome.     

Correlation between synthesis variation of 2-alkylquinolones and the antifungal activity of a Burkholderia cepacia strain collection

Twenty epiphytic and rhizospheric bacterial strains harbouring strong antifungal activities were isolated from the Tunisian environment. This group of bacteria was identified as Burkholderia cepacia genomovar I using 16S rDNA and recA fragment gene sequence analyses for two selected strains and RFLP technique for the eighteen other ones. This identification did not show variability between isolates despite the significant differences in the antifungal activities of their culture supernatant and the organic crude extract against Aspergillus niger and other phytopathogenic fungi. Chromatographic and mass spectrometric analyses of these extracts allowed us to confirm the difference between strains of the group. Their metabolic production showed differences in term of contents and quantities of secreted molecules, particularly those which were identified to be involved in the antifungal activities. Two metabolites, named Bc-255 and Bc-257 secreted by the entire group at different amounts, have been purified and tested separately against A. niger. Bc-255 showed an activity twice as high as those shown by Bc-257. The structural characterization of these two compounds by mass spectrometry and nuclear magnetic resonance spectroscopy allowed their identification as two analogous 2-alkylquinolones with only one difference at the alkyl chain.