Responses of Cymbopogon schoenanthus to salt stress

Cymbopogon schoenanthus is an aromatic and medicinal plant rich in essential oil. The physiological behavior of this species, related with growth production, the photosynthetic pigments, the nutritional status and the osmotic adjustment were studied. Saline treatments varied from 0 to 150 mM NaCl. The results show that the growth of C. schoenanthus was affected by the salinity and the effect increased with more stress at 100 mM of NaCl. Besides the response of C. schoenanthus to the salt stress, this study has allowed us to conclude that this plant is excluder glycophyte and less tolerant to salt stress.Key words: Cymbopogon schoenanthus, NaCl, growth, mineral nutrition, osmotic adjustment

Physical mapping of ribosomal DNA and genome size in diploid and polyploid North African Calligonum species (Polygonaceae).

Most Calligonum species are desert plants, characteristic of the Saharan bioclimatic region. All species karyologically analyzed until present have the basic chromosome number x = 9 and comprise diploids, triploids and tetraploids. The Tunisian flora comprises diploid Calligonum arich and C. azel, of restricted distribution, and the tetraploid C. comosum with wider distribution. Analyses of their karyotypes and polyploidisation-linked rDNA changes by orcein staining, fluorochrome banding with chromomycin A3 and fluorescent in situ hybridisation with 5S and 26S ribosomal DNA probes have been performed. We report the chromosome number for Calligonum arich (2n = 18) as well as the diploid level for C. comosum for the first time. Chromosome counts have also verified the earlier described tetraploid cytotype (2n = 36) of C. comosum. A general pattern of six GC-rich bands as well as two 35S sites and four 5S sites is described for Calligonum species at the diploid level although there is intraspecific variation regarding the site number in a second type of C. comosum, with one pair of 35S rDNA sites and two pairs of 5S rDNA sites. The tetraploid cytotype of C. comosum has undergone locus loss and genome downsizing. Genome size assessments confirmed previous data. Nonetheless, statistically significant differences were found depending on the type of tissue used for estimation. Measurements from seeds had always larger values than from leaves. The presence of cytosolic compounds in leaves, interfering with DNA staining, is discussed as a possible cause of the differences

Thermal stability of the essential oils isolated from Tunisian Thymus capitatus Hoff. et Link.: Effect on the chemical composition and the antioxidant and antibacterial activities

The chemical composition, the antioxidant and the antibacterial activities of essential oils, isolated from the aerial parts of Tunisian Thymus capitatus during the flowering phase, and stored in the dark during 37 days in the oven, at 60 degrees C were evaluated. Samples taken periodically were used to evaluate the chemical composition, the antioxidant and the antibacterial activities. With some fluctuations, carvacrol (68-74%) was the major component of the oil independent of the storage period. alpha-Terpinene and gamma-terpinene decreased over time, whereas p-cymene increased in the same period. Despite the thirty-seven days of storage at 60 degrees C, T. capitatus essential oil still showed high antioxidant and stable antimicrobial activity

UDTN-RS : A new underwater delay tolerant network routing protocol for coastal patrol and surveillance

The Coastal Patrol and Surveillance Application (CPSA) is developed and deployed to detect, track and monitor water vessel traffic using automated devices. The latest advancements of marine technologies, including Automatic Underwater Vehicles, have encouraged the development of this type of applications. To facilitate their operations, installation of a Coastal Patrol and Surveillance Network (CPSN) is mandatory. One of the primary design objectives of this network is to deliver an adequate amount of data within an effective time frame. This is particularly essential for the detection of an intruder's vessel and its notification through the adverse underwater communication channels. Additionally, intermittent connectivity of the nodes remains another important obstacle to overcome to allow the smooth functioning of CPSA. Taking these objectives and obstacles into account, this work proposes a new protocol by ensembling forward error correction technique (namely Reed-Solomon codes or RS) in Underwater Delay Tolerant Network with probabilistic spraying technique (UDTN-Prob) routing protocol, named Underwater Delay Tolerant Protocol with RS (UDTN-RS). In addition, the existing binary packet spraying technique in UDTN-Prob is enhanced for supporting encoded packet exchange between the contacting nodes. A comprehensive simulation has been performed employing DEsign, Simulate, Emulate and Realize Test-beds (DESERT) underwater simulator along with World Ocean Simulation System (WOSS) package to receive a more realistic account of acoustic propagation for identifying the effectiveness of the proposed protocol. Three scenarios are considered during the simulation campaign, namely varying data transmission rate, varying area size, and a scenario focusing on estimating the overhead ratio. Conversely, for the first two scenarios, three metrics are taken into account: normalised packet delivery ratio, delay, and normalised throughput. The acquired results for these scenarios and metrics are compared to its ancestor, i.e., UDTN-Prob. The results suggest that the proposed UDTN-RS protocol can be considered as a suitable alternative to the existing protocols like UDTN-Prob, Epidemic, and others for sparse networks like CPSN