Variation in Volatile Leaf Oils of 13 Eucalyptus Species Harvested from Souinet Arboreta (Tunisia)

Hydrodistillation of the dried leaves of 13 species of the genus Eucalyptus L' Hér ., viz., E. bicostata Maiden, Blakely & Simmonds , E. cinerea F. Muell . ex Benth ., E. exerta F. Muell ., E. gigantea Hook . f ., E. gunnii Hook . f ., E. macarthurii Deane & Maiden ., E. macrorrhyncha F. Muell ., E. maidenii F. Muell ., E. odorata Behr ., E. pauciflora Sieber ex Sprengel , E. sideroxylon A. Cunn . ex Woolls , E. tereticornis Sm ., and E. viminalis Labill ., harvested from Souinet arboreta (region of Ain Draaham, north of Tunisia) in June 2006, afforded essential oils in yields varying from 0.5±0.2 to 3.9±0.4%, dependent on the species. E. cinerea and E. exerta provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 142 components, representing 81.5 to 98.9% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 1 ), followed by cryptone, spathulenol ( 4 ), p‐cymene ( 2 ), viridiflorol ( 6 ), globulol ( 7 ), β‐eudesmol, α‐terpineol ( 5 ), limonene ( 8 ), D ‐piperitone, α‐pinene ( 3 ), cuminal, and γ‐eudesmol. The principal component and the hierarchical cluster analyses separated the 13 Eucalyptus leaf essential oils into three groups, each constituting a chemotype.     

Mitochondrial dysfunction in NASH: causes, consequences and possible means to prevent it

Calorie-enriched diet and lack of exercise are causing a worldwide surge of obesity, insulin resistance and lipid accretion in liver (i.e. hepatic steatosis), which can lead to steatohepatitis. Steatosis and nonalcoholic steatohepatitis (NASH) can also be induced by drugs such as amiodarone, tamoxifen and some antiretroviral drugs, including stavudine and zidovudine. There is accumulating evidence that mitochondrial dysfunction (more particularly respiratory chain deficiency) plays a key role in the physiopathology of NASH whatever its initial cause. In contrast, the mitochondrial beta-oxidation of fatty acids can be either increased (as in insulin resistance-associated NASH) or decreased (as in drug-induced NASH). However, in both circumstances, generation of reactive oxygen species (ROS) by the damaged respiratory chain can be augmented. ROS generation in an environment enriched in lipids in turn induces lipid peroxidation which releases highly reactive aldehydic derivatives (e.g. malondialdehyde) that have diverse detrimental effects on hepatocytes and other hepatic cells. In hepatocytes, ROS, reactive nitrogen species and lipid peroxidation products further impair the respiratory chain, either directly or indirectly through oxidative damage to the mitochondrial genome. This consequently leads to the generation of more ROS and a vicious cycle occurs. Mitochondrial dysfunction can also lead to apoptosis or necrosis depending on the energy status of the cell. ROS and lipid peroxidation products also increase the generation of several cytokines (TNF-alpha, TGF-beta, Fas ligand) playing a key role in cell death, inflammation and fibrosis. Recent investigations have shown that some genetic polymorphisms can significantly increase the risk of steatohepatitis and that several drugs can prevent or even reverse NASH. Interestingly, most of these drugs could exert their beneficial effects by improving directly or indirectly mitochondrial function in liver. Finding a drug, which could fully prevent oxidative stress and mitochondrial dysfunction in NASH is a major challenge for the next decade.     

Genetic diversity in Tunisia: a study based on the GM polymorphism of human immunoglobulins

The GM polymorphism of human immunoglobulins is analyzed in three Berber populations of southern Tunisia and compared to other GM data. Genetic diversity among Tunisian populations is higher than that among Europeans but does not exhibit any significant geographic or linguistic structure. This result suggests a complex pattern of genetic differentiation.     

A thermostable glucose isomerase having a relatively low optimum pH: study of activity and molecular cloning of the corresponding gene

A thermostable glucose isomerase from a newly isolated thermophilic Streptomyces sp. SK strain, had a wide pH range with an optimum of 6 at 60°C and 6.4 at 90°C. It was optimally active at 95°C and completely stable at 80°C for at least 5.5 h with a half-life of 5 h at 90°C. Using E.coli as a host strain and an internal fragment of xylA of S. olivochromogenes as a probe, a 6.5 kb DNA fragment from Streptomyces sp. SK was cloned. This fragment carries the entire xylA gene since the recombinant plasmid complements the E.coli xyl-5 mutant strain HB101. © Rapid Science Ltd. 1998     

Palmitic acid conjugation enhances potency of tricyclo-DNA splice switching oligonucleotides

Tricyclo-DNA (tcDNA) is a conformationally constrained oligonucleotide analog that has demonstrated great therapeutic potential as antisense oligonucleotide (ASO) for several diseases. Like most ASOs in clinical development, tcDNA were modified with phosphorothioate (PS) backbone for therapeutic purposes in order to improve their biodistribution by enhancing association with plasma and cell protein. Despite the advantageous protein binding properties, systemic delivery of PS-ASO remains limited and PS modifications can result in dose limiting toxicities in the clinic. Improving extra-hepatic delivery of ASO is highly desirable for the treatment of a variety of diseases including neuromuscular disorders such as Duchenne muscular dystrophy. We hypothesized that conjugation of palmitic acid to tcDNA could facilitate the delivery of the ASO from the bloodstream to the interstitium of the muscle tissues. We demonstrate here that palmitic acid conjugation enhances the potency of tcDNA-ASO in skeletal and cardiac muscles, leading to functional improvement in dystrophic mice with significantly reduced dose of administered ASO. Interestingly, palmitic acid-conjugated tcDNA with a full phosphodiester backbone proved effective with a particularly encouraging safety profile, offering new perspectives for the clinical development of PS-free tcDNA-ASO for neuromuscular diseases.     

Seasonal reproduction of Porcellio variabilis Lucas, 1846

Porcellio variabilis is common and very widespread in Tunisia. Its breeding period lasts from February to October with a cessation during the months of November, December and January. The recruitment of young takes place principally between April and July. Virgin and mated females reared with natural photoperiod in the laboratory show that the initiation of reproduction does not depend on mating; however, it is accelerated when the male is present, the preparturial moult being shorter in females reared in the presence of a male.     

Lithostratigraphy and sedimentology of the latest Cretaceous-early Burdigalian Tamezzakht succession (Northern Rif, Morocco): consequences for its sequence stratigraphic interpretation

The Tamezzakht succession (Maastrichtian–middle Burdigalian), situated at the fringe between the Internal and the External zones, displays contrasting lithologies with abrupt facies changes, discontinuities, and/or coarse-grained calciturbidite in between. These criteria allow the definition of seven main lithostratigraphic formations.Depositional environments (oxygenation levels, trophic conditions, omission histories, among others) and/or transgressive/regressive trends are inferred from integrated sedimentologic data including facies change, cyclicity pattern and the textural composition of the turbidite facies tracts. Special emphasis is given to the ichnological features.Taking into account the extended time-range, the position between the internal zones and the external ones, as well as the clear differentiation into several contrasting sedimentary formations, the Tamezzakht succession is expected to provide useful stratigraphic data for the regional correlations.     

DNA vector-based RNAi approach for stable depletion of poly(ADP-ribose) polymerase-1

RNA-mediated interference (RNAi) is a powerful technique that is now being used in mammalian cells to specifically silence a gene. Some recent studies have used this technique to achieve variable extent of depletion of a nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1). These studies reported either transient silencing of PARP-1 using double-stranded RNA or stable silencing of PARP-1 with a DNA vector which was introduced by a viral delivery system. In contrast, here we report that a simple RNAi approach which utilizes a pBS-U6-based DNA vector containing strategically selected PARP-1 targeting sequence, introduced in the cells by conventional CaPO(4) protocol, can be used to achieve stable and specific silencing of PARP-1 in different types of cells. We also provide a detailed strategy for selection and cloning of PARP-1-targeting sequences for the DNA vector, and demonstrate that this technique does not affect expression of its closest functional homolog PARP-2.     

Locomotor behaviour in males,females and groups of Orchestia montagui (Amphipoda,Talitridae) in the supralittoral zone of Bizerte lagoon

Locomotor activity rhythm of Orchestia montagui was investigated under constant darkness in a population collected in spring from the supralittoral zone of Bizerte lagoon (northern region of Tunisia) at Menzel Jmil in spring. This rhythm was recorded in individual and groups of animal by infrared actography every 20 min by multichannel data loggers, at a constant temperature of 18 ± 0.5 °C. According to double-plotted actograms, wave forms and periodogram analysis, results revealed different locomotor pattern. However, locomotor activity rhythm of males was more stable than females. Furthermore, the mortality was statistically higher in unmixed groups than in mixed groups.