Analysis of molecular genetic diversity of cardoon (Cynara cardunculus L.) in Tunisia

The objective of this study is to investigate the genetic diversity, the relationships among six Tunisian wild cardoon populations (Cynara cardunculus var. sylvestris) and a Tunisian's population of cultivated cardoon (Cynara cardunculus var. altilis DC) in seven different geographical locations (Tiurif, Bahra, Zriba, Bouficha, Enfidha, Beja and Wad mliz) from semi-arid and wet regions of Tunisia. Twenty-three selected microsatellite markers are used for a sample of 98 cardoon genotypes. The total of 243 alleles is detected in the studied populations and the number of alleles per locus ranged from six to 23. The dendrogram based on Nei's (1972) UPGMA method divides the seven studied populations to five clusters. These preliminary results show that microsatellites are effective tools for plant species characterization and the analysed populations have a high genetic variability and will be suitable as genetic stocks for conservation and sustainable utilization programs of Cynara cardunculus L. in Tunisia.     

Early thyroid development requires a Tbx1-Fgf8 pathway

The thyroid develops within the pharyngeal apparatus from endodermally-derived cells. The many derivatives of the pharyngeal apparatus develop at similar times and sometimes from common cell types, explaining why many syndromic disorders express multiple birth defects affecting different structures that share a common pharyngeal origin. Thus, different derivatives may share common genetic networks during their development. Tbx1, the major gene associated with DiGeorge syndrome, is a key player in the global development of the pharyngeal apparatus, being required for virtually all its derivatives, including the thyroid. Here we show that Tbx1 regulates the size of the early thyroid primordium through its expression in the adjacent mesoderm. Because Tbx1 regulates the expression of Fgf8 in the mesoderm, we postulated that Fgf8 mediates critical Tbx1-dependent interactions between mesodermal cells and endodermal thyrocyte progenitors. Indeed, conditional ablation of Fgf8 in Tbx1-expressing cells caused an early thyroid phenotype similar to that of Tbx1 mutant mice. In addition, expression of an Fgf8 cDNA in the Tbx1 domain rescued the early size defect of the thyroid primordium in Tbx1 mutants. Thus, we have established that a Tbx1->Fgf8 pathway in the pharyngeal mesoderm is a key size regulator of mammalian thyroid.     

P130Cas-associated protein (p140Cap) as a new tyrosine-phosphorylated protein involved in cell spreading

Integrin-mediated cell adhesion stimulates a cascade of signaling pathways that control cell proliferation, migration, and survival, mostly through tyrosine phosphorylation of signaling molecules. p130Cas, originally identified as a major substrate of v-Src, is a scaffold molecule that interacts with several proteins and mediates multiple cellular events after cell adhesion and mitogen treatment. Here, we describe a novel p130Cas-associated protein named p140Cap (Cas-associated protein) as a new tyrosine phosphorylated molecule involved in integrin- and epidermal growth factor (EGF)-dependent signaling. By affinity chromatography of human ECV304 cell extracts on a MBP-p130Cas column followed by mass spectrometry matrix-assisted laser desorption ionization/time of flight analysis, we identified p140Cap as a protein migrating at 140 kDa. We detected its expression in human, mouse, and rat cells and in different mouse tissues. Endogenous and transfected p140Cap proteins coimmunoprecipitate with p130Cas in ECV304 and in human embryonic kidney 293 cells and associate with p130Cas through their carboxy-terminal region. By immunofluorescence analysis, we demonstrated that in ECV304 cells plated on fibronectin, the endogenous p140Cap colocalizes with p130Cas in the perinuclear region as well as in lamellipodia. In addition p140Cap codistributes with cortical actin and actin stress fibers but not with focal adhesions. We also show that p140Cap is tyrosine phosphorylated within 15 min of cell adhesion to integrin ligands. p140Cap tyrosine phosphorylation is also induced in response to EGF through an EGF receptor dependent-mechanism. Interestingly expression of p140Cap in NIH3T3 and in ECV304 cells delays the onset of cell spreading in the early phases of cell adhesion to fibronectin. Therefore, p140Cap is a novel protein associated with p130Cas and actin cytoskeletal structures. Its tyrosine phosphorylation by integrin-mediated adhesion and EGF stimulation and its involvement in cell spreading on matrix proteins suggest that p140Cap plays a role in controlling actin cytoskeleton organization in response to adhesive and growth factor signaling.     

The newly synthesized plant growth regulator <Emphasis Type="Italic">S</Emphasis>-methylmethionine salicylate may provide protection against high salinity in wheat

High salinity is one of the major environmental factors limiting the productivity of crop species worldwide. Improving the stress tolerance of cultivated plants and thus increasing crop yields in an environmentally friendly way is a crucial task in agriculture. In the present work the ability of a new derivative, S-methylmethionine-salicylate (MMS), to improve the salt tolerance of wheat plants was tested parallel with its related compounds salicylic acid and S-methylmethionine. The results show that while these compounds are harmful at relatively high concentration (0.5 mM), they may provide protection against high salinity at lower (0.1 mM) concentration. This was confirmed by gas exchange, chlorophyll content and chlorophyll-a fluorescence induction measurements. While osmotic adjustment probably plays a critical role in the improved salt tolerance, neither Na or K transport from the roots to the shoots nor proline synthesis are the main factors in the tolerance induced by the compounds tested. MMS, S-methylmethionine and Na-salicylate had different effects on flavonol biosynthesis. It was also shown that salt treatment had a substantial influence on the SA metabolism in wheat roots and leaves. Present results suggest that the investigated compounds can be used to improve salt tolerance in plants.     

Oxidative and nitrative modifications of enkephalins by reactive nitrogen species

The interaction of Leucine-enkephalin (Leu-enkephalin) with reactive nitrogen species has been investigated. Reactive nitrogen species are capable of nitrating and oxidizing Leu-enkephalin. HPLC analysis shows the formation of two major enkephalin derivatives by peroxynitrite. The tyrosine amino-terminal residue of Leu-enkephalin is converted either to 3-nitrotyrosine thus producing nitroenkephalin and to dityrosine by dimerization with the production of an enkephalin dimer. The evidence of the formation of the nitroenkephalin and of the enkephalin dimer—dienkephalin—was achieved by electrospray ionisation mass spectrometry. In addition to peroxynitrite, the methylene blue photosensitized oxidation of enkephalin in the presence of nitrite leads to the formation of the nitrated peptide. Moreover, the nitropeptide can be also obtained by peroxidase-generated nitrogen reactive species.     

An index of 5-HT synthesis changes during early antidepressant treatment: alpha-[11C]methyl-L-tryptophan PET study

The antidepressant selective serotonin transporter inhibitors (SSRIs) are clinically active after a delay of several weeks. Indeed, the rapid increase of serotonin (5-HT) caused by SSRIs, stimulates the 5-HT(1A) autoreceptors, which exert a negative feedback on the 5-HT neurotransmission. Only when autoreceptors are desensitized, can SSRIs exert their therapeutic activity. The 5-HT(1A) receptor antagonist pindolol has been used to accelerate the clinical effects of antidepressant by preventing the negative feedback. Using the alpha-[(11)C]methyl-L-tryptophan/positron emission tomography (PET), the goal of the present double-blind, randomized study was to compare the changes in alpha-[(11)C]methyl-L-tryptophan trapping, an index of serotonin synthesis, in patients suffering from unipolar depression treated with the SSRI citalopram (20 mg/day) plus placebo versus patients treated with citalopram plus pindol (7.5 mg/day). PET and Hamilton depression rating scale (HDRS-17) were performed at baseline, and after 10 and 24 days of antidepressant treatment. Results show that the combination citalopram plus pindol, compared to citalopram alone shows a more rapid and greater increase of an index of 5-HT synthesis in prefrontal cortex (BA 9). This research is the first human PET study demonstrating that, after 24 days, the combination SSRIs plus pindolol produces a greater increase of the metabolism of serotonin in the prefrontal cortex, an area associated to depressive symptoms.     

Effect of prenatal treatment with methylazoxymethanol on carbachol-, norepinephrine- and glutamate-stimulated phosphoinositide metabolism in the neonatal,young, and adult offspring

Carbachol-, norepinephrine- and glutamate-stimulated phosphoinositide metabolism was investigated in the neonatal, young and adult cerebral cortex slices of rats prenatally treated with methylazoxymethanol (MAM) on gestational day 15 (GD15) or GD19. In rat offspring treated on GD15 there was a significant reduction in the accumulation of [³H]inositol phosphates induced by carbachol and a significant increase in the accumulation of [³H]inositol phosphates induced by norepinephrine on day 7, whereas no changes were observed at the other ages. No significant changes, on the other hand, were observed for glutamate-stimulated phosphoinositide metabolism in GD15 treated rats and for carbachol-, norepinephrine- and glutamate-stimulated phosphoinositide metabolism in animals treated on GD19 at any of the different ages evaluated. These results indicate that treatment with MAM on GD15, which results in a marked microencephaly, causes a marked alteration of muscarinic and ₁-adrenergic receptor-stimulated phosphoinositide metabolism during brain development and that these alterations undergo adaptive changes in the adult brain.