Water Relations, Gas Exchange, Chlorophyll Fluorescence and Electrolyte Leakage of Ectomycorrhizal Pinus halepensis Seedlings in Response to Multi-Heavy Metal Stresses (Pb, Zn, Cd).

The success of mine site restoration programs in arid and semi-arid areas poses a significant challenge and requires the use of high-quality seedlings capable of tolerating heavy metal stresses. The effect of ectomycorrhizal fungi on different physiological traits was investigated in Pinus halepensis seedlings grown in soil contaminated with heavy metals (Pb-Zn-Cd). Ectomycorrhizal (M) and non-ectomycorrhizal (NM) seedlings were subjected to heavy metals stress (C: contaminated, NC: control or non-contaminated) soils conditions for 12 months. Gas exchange, chlorophyll fluorescence, water relations parameters derived from pressure-volume curves and electrolyte leakage were evaluated at 4, 8 and 12 months. Ectomycorrhizal symbiosis promoted stronger resistance to heavy metals and improved gas exchange parameters and water-use efficiency compared to the non-ectomycorrhizal seedlings. The decrease in leaf osmotic potentials (Ψπ100: osmotic potential at saturation and Ψπ0: osmotic potential with loss of turgor) was higher for M-C seedling than NM-C ones, indicating that the ectomycorrhizal symbiosis promotes cellular osmotic adjustment and protects leaf membrane cell against leakage induced by Pb, Zn and Cd. Our results suggest that the use of ectomycorrhizal symbiosis is among the promising practices to improve the morphophysiological quality of seedlings produced in forest nurseries, their performance and their tolerance to multi-heavy metal stresses.

Effects of Ectomycorrhizal Fungi and Heavy Metals (Pb, Zn, and Cd) on Growth and Mineral Nutrition of Pinus halepensis Seedlings in North Africa.

The pollution of soils by heavy metals resulting from mining activities is one of the major environmental problems in North Africa. Mycorrhizoremediation using mycorrhizal fungi and adapted plant species is emerging as one of the most innovative methods to remediate heavy metal pollution. This study aims to assess the growth and the nutritional status of ectomycorrhizal Pinus halepensis seedlings subjected to high concentrations of Pb, Zn, and Cd for possible integration in the restoration of heavy metals contaminated sites. Ectomycorrhizal and non-ectomycorrhizal P. halepensis seedlings were grown in uncontaminated (control) and contaminated soils for 12 months. Growth, mineral nutrition, and heavy metal content were assessed. Results showed that ectomycorrhizae significantly improved shoot and roots dry masses of P. halepensis seedlings, as well as nitrogen shoot content. The absorption of Pb, Zn, and Cd was much higher in the roots than in the shoots, and significantly more pronounced in ectomycorrhizal seedlings-especially for Zn and Cd. The presence of ectomycorrhizae significantly reduced the translocation factor of Zn and Cd and bioaccumulation factor of Pb and Cd, which enhanced the phytostabilizing potential of P. halepensis seedlings. These results support the use of ectomycorrhizal P. halepensis in the remediation of heavy metal contaminated sites.

Risk factors of the failure of surfactant treatment by transient intubation during nasal continuous positive airway pressure in preterm infants.

We sought to identify risk factors and neonatal outcomes associated with the failure of the INSURE method ( INtubation- SURfactant- Extubation) during nasal continuous positive airway pressure for preterm infants with respiratory distress syndrome. We used a retrospective analysis of the prenatal histories, clinical courses, and laboratory data of all inborn infants with gestational age 27 to 34 weeks and respiratory distress syndrome treated with INSURE method. Infants were categorized into two groups: INSURE failure group and INSURE success group. One hundred nine infants were eligible to the study. INSURE failure was registered in 35 infants (32.1%). After control for confounding variables, INSURE failure was significantly associated with arterial partial pressure of carbon dioxide (adjusted odds ratio [OR] = 1.82; 95% confidence interval [CI] = 1.76 to 90.56), mean arterial-to-alveolar oxygen tension ratio (adjusted OR = 1.13; 95% CI = 1.06 to 85.34) and severe radiological grade (adjusted OR = 1.31; 95% CI = 1.15 to 70.16). Positive predictive values of these variables were 70, 75, and 55%, respectively. Patent ductus arteriosus and mortality rates were significantly higher in INSURE failure group. Arterial partial pressure of carbon dioxide, arterial-to-alveolar oxygen tension ratio, and severe radiological grade are predictors of the failure of INSURE method in preterm infants with respiratory distress syndrome. However, a prospective randomized controlled trial is needed to determine whether or not infants at risk for INSURE failure are better off being treated with mechanical ventilation.