Exogenous proline mediates alleviation of cadmium stress by promoting photosynthetic activity, water status and antioxidative enzymes activities of young date palm (Phoenix dactylifera L.).

The ability of exogenous compatible solutes, such as proline, to counteract cadmium (Cd) inhibitory effects in young date palm plants (Phoenix dactylifera L. cv Deglet Nour) was investigated. Two-year-old date palm plants were subjected for five months at different Cd stress levels (0, 10 and 30 mg CdCl2 kg(-1) soil) whether supplied or not with exogenous proline (20mM) added through the irrigation water. Different levels of Cd stress altered plant growth, gas exchanges and chlorophyll content as well as water status, but at different extent among them. In contrast, an increase of antioxidant enzymes activities of Cd-treated plants in association with high amounts of proline content, hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) and electrolyte leakage (EL) were observed. Interestingly, exogenous proline mitigated the adverse effects of Cd on young date palm. Indeed, it alleviated the oxidative damage induced by Cd accumulation and established better levels of plant growth, water status and photosynthetic activity. Moreover, proline-treated plants showed high antioxidant enzymes activities (superoxide dismutase, catalase and glutathione peroxydase) in roots and leaves as compared to Cd-treated plants.

Effect of arsenate As (V) on the biomarkers of Myriophyllum alterniflorum in oligotrophic and eutrophic conditions.

Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte found in the Limousin rivers (France) whose potential for biomonitoring of metal pollution has been demonstrated. The objective of the present study carried out in vitro was to identify biomarkers for an early detection of the pollution by a metalloid As (V) in eutrophic and oligotrophic conditions. A synthetic medium of similar composition to the waters of the River Vienne was prepared. The morphological development of watermilfoil was monitored for 30 days, with or without contamination by 100 µg L(-1) As (V). In addition, the mineralization of plants and the analysis of biomarkers (chlorophylls, photosynthetic and respiratory intensities …) were investigated after 21 days. Our results indicated that eutrophic medium, induced a decrease in chlorophyll pigments, in growth and an increase in H2O2 compared to the oligotrophic medium. While, the presence of As (V), led to a decrease in the osmotic potential, pigment content, photosynthesis and respiration rates and an inhibition of shoot branching of plants in both conditions. However, a significant increase in H2O2 content was noted in the eutrophic medium. Finally, As (V) was found to be more accumulated in roots than shoots in both conditions but was more accumulated in oligotrophic one. Therefore, we can conclude that the water trophic level modifies the response of M. alterniflorum in presence of arsenate. Thus, M. alterniflorum shows a great promise in water-quality biomonitoring.

Soil fluoride spiking effects on olive trees (Olea europaea L. cv. Chemlali).

A pot experiment under open air conditions was carried out to investigate the uptake, accumulation and toxicity effects of fluoride in olive trees (Olea europaea L.) grown in a soil spiked with inorganic sodium fluoride (NaF). Six different levels (0, 20, 40, 60, 80 and 100mM NaF) of soil spiking were applied through NaF to irrigation water. At the end of the experiment, total fluoride content in soil was 20 and 1770mgFkg(-1) soil in control and 100mM NaF treatments, respectively. The comparative distribution of fluoride partitioning among the different olive tree parts showed that the roots accumulated the most fluoride and olive fruits were minimally affected by soil NaF spiking as they had the lowest fluoride content. In fact, total fluoride concentration varied between 12 and 1070µgFg(-1) in roots, between 9 and 570µgFg(-1) in shoots, between 12 and 290µgFg(-1) in leaves, and between 10 and 29µgFg(-1) in fruits, respectively for control and 100mM NaF treatments. Indeed, the fluoride accumulation pattern showed the following distribution: roots>shoots>leaves>fruits. On the other hand, fluoride toxicity symptoms such as leaf necrosis and leaf drop appeared only in highly spiked soils (60, 80 and 100mM NaF).

Differences in SMN1 allele frequencies among ethnic groups within North America.

BACKGROUND: Spinal muscular atrophy (SMA) is the most common inherited lethal disease of children. Various genetic deletions involving the bi-allelic loss of SMN1 exon 7 are reported to account for 94% of affected individuals. Published literature places the carrier frequency for SMN1 mutations between 1 in 25 and 1 in 50 in the general population. Although SMA is considered to be a pan-ethnic disease, carrier frequencies for many ethnicities, including most ethnic groups in North America, are unknown. OBJECTIVES AND METHODS: To provide an accurate assessment of SMN1 mutation carrier frequencies in African American, Ashkenazi Jewish, Asian, Caucasian, and Hispanic populations, more than 1000 specimens in each ethnic group were tested using a clinically validated, quantitative real-time polymerase chain reaction (PCR) assay that measures exon 7 copy number. RESULTS: The observed one-copy genotype frequency was 1 in 37 (2.7%) in Caucasian, 1 in 46 (2.2%) in Ashkenazi Jew, 1 in 56 (1.8%) in Asian, 1 in 91 (1.1%) in African American, and 1 in 125 (0.8%) in Hispanic specimens. Additionally, an unusually high frequency of alleles with multiple copies of SMN1 was identified in the African American group (27% compared to 3.3-8.1%). This latter finding has clinical implications for providing accurate adjusted genetic risk assessments to the African American population. CONCLUSIONS: Differences in the frequency of SMA carriers were significant among several ethnic groups. This study provides an accurate assessment of allele frequencies and estimates of adjusted genetic risk that were previously unavailable to clinicians and patients considering testing.

[Seroepidemiologic study of sexually transmitted diseases caused by Chlamydia trachomatis in Casablanca (Morocco)]. / Enquête séro-épidémiologique sur les MST a Chlamydia trachomatis a Casablanca (Maroc).

Screening 579 sera specimens obtained in Casablanca (Morocco) we have performed a retrospective seroepidemiological survey with regard to the prevalence of Chlamydia trachomatis involved in genital tract infections. The surveyed populations are divided into 3 groups: 177 patients affected with sexually transmitted diseases (STD), 319 reference patients, 83 maghrebian patients affected with STD but living in France. The study was performed by the indirect microimmunofluorescence technique. The prevalence of Chlamydia trachomatis ranging from 50% in the moroccan reference groupe to about 70% among patients with STD both in Morocco and Bordeaux indicates that Chlamydia trachomatis takes a significant part in STD observed in moroccan populations.