Correlation of Peroxisome Proliferator-Activated Receptor (PPAR-γ) mRNA Expression with Pro12Ala Polymorphism in Obesity

Our study aimed to analyze whether the expression of PPARγ mRNA in subcutaneous adipocyte tissue correlates with Pro12Ala PPARγ2 polymorphism in the obesity context. We found that mRNA expression of PPARγ in subcutaneous adipose tissue was greater in obese subjects (P < 0.05) than in the nonobese control group. Concurrently, genotyping of the Pro12Ala polymorphism showed that obese subjects possess a significantly higher frequency of the Pro/Pro genotype than nonobese controls (90.5 vs 79.5%; P = 0.03), suggesting that this genotype is involved in an increased risk of obesity in the Tunisian population. Taken together, our results demonstrate that the Pro12 allele is accompanied by an overexpression of PPARγ mRNA in subcutaneous adipocyte tissue, suggesting that the PPARγ Pro12Ala variant may contribute to the observed variability in PPARγ mRNA expression and consequently in body mass index and insulin sensitivity in the general population.     

Essential oils from two Eucalyptus from Tunisia and their insecticidal action on Orgyia trigotephras (Lepidotera,Lymantriidae)

Background

Essential oils extracted from aromatic and medicinal plants have many biological properties and are therefore an alternative to the use of synthetic products. The chemical composition of essential oils from two medicinal plants (Eucalyptus globulus and E. lehmannii) was determined and, their insecticidal effects on the third and fourth larval stages of Orgyia trigotephras were assessed.

Results

Larvae were collected from Jebel Abderrahmane (North-East of Tunisia), conserved in groups of 50/box (21 × 10 × 10 cm) at a temperature of 25°C. Larvae were tested for larvicidal activities of essential oils. Each oil was diluted in ethanol (96%) to prepare 3 test solutions (S1 = 0.05%, S2 = 0.10% and S3 = 0.50%). Essential oils were used for contact, ingestion and Olfactory actions and compared to reference products (Bacillus thuringiensis and Decis). Olfactory action of essential oils shows that larvae mortality is higher than contact action, lower than ingestion action. MTM and FTM of S3 of E. lehmannii were respectively 1 h 32 min and 1 h 39 min are higher than those of E. globulus (MTM = 51 min and FTM = 1 h 22 min 34 sec). Contact action of E. lehmannii oil shows low insecticidal activity compared to E. globulus. MTM are respectively (1 min 52 sec and 1 min 7 sec), FTM are (2 min 38 sec, 1 min 39 sec), are the shortest recorded for S3, on the third stage of larvae. The fourth stage of larvae, MTM are (2 min 20 sec and 2 min 9 sec), FTM are (3 min 25 sec, 3 min 19 sec). Ingestion action of essential oils is longer than the contact action, since the time of death exceeds 60 minutes for all species.

Conclusion

Results shows that essential oils have a toxic action on nerves leading to a disruption of vital system of insects. High toxic properties make these plant-derived compounds suitable for incorporation in integrated pest management programs.     

Evaluation of the relative cell surface charge by using microbial adhesion to hydrocarbon

A simple and rapid method, Microbial adhesion to hexadecane, for estimating the cell surface charge is proposed. This method is based on the determination of cell affinity to hexadecane at low ionic strength and at high ionic strength. The difference between these two affinities can provide the relative cell surface charge. The application of this method for Staphylococcus aureus and Escherichia coli show that the profile of surface charge evolution as a function of pH was similar to these obtained by microelectrophoresis method.     

Conservation of Mediterranean wetlands: interest of historical approach

The wetlands of North Africa are an endangered and invaluable ecological heritage. Some of these wetlands are now protected by various conservation statutes; which actual impact has not yet been reliably evaluated. This article aims to assess the conservation management (Nature Reserve and Ramsar site) of a protected Tunisian lake, Majen Chitane, by using palaeoecological, historical and modern data, and by comparing it with the unprotected lake Majen Choucha. While located in similar environments, these lakes are today home to very different flora. Baseline conditions reconstructed from literature indicate that both lakes were very similar until the 1950s, and comparable to the current state of Majen Choucha, housing rich oligotrophic plant communities. In the 1960s, at the time that cultivation of the adjacent peatland began, Majen Chitane underwent strong ecological changes as the initial oligotrophic plant, diatom and zooplankton communities were replaced by eutrophication-tolerant ones. Eutrophication led to the local extinction of 40–55% of the hydrophytic and temporary-pool plant species, including those characteristic of the Isoetion. Given the damages and despite the recent conservation status of the site, it's unlikely that Majen Chitane will undergo any natural regeneration. Restoring it would start with completely protecting the complex lake-peatland and re-introducing the locally extinct species from Majen Choucha. This work exemplifies the usefulness of connecting palaeoecological, historical and modern data for the conservation of Mediterranean wetlands.     

Structures de végétation et conservation des zones humides temporaires méditerranéennes : la région des Mogods (Tunisie septentrionale)

Floristic surveys and phytoecological relevés were conducted on 36 temporary wetlands of Mogods region. Multivariate analyses (CA, AHC) performed on these data reveal the high specific and biocoenotic diversity of Mogods wetlands, which appear controlled by substrate nature and hydrology. Among the 128 hydrophytic species inventoried, 38 are presently in precarious status and 6 are presumed extinct. The Mogods region harbours, moreover, very rare habitats (peatlands and semi-permanent lakes), and a vast plain so-called Garâa Sejenane, exceptionally rich in temporary wetlands. These results underline the urgency of an adapted conservatory management, based on the development of scientific studies dealing with structure and functioning of hydrophytic communities of the region.