Isolation and characterization of rhizosphere bacteria for the biocontrol of the damping-off disease of tomatoes in Tunisia

Fluorescent Pseudomonas spp., isolated from tomato and pepper plants rhizosphere soil, was evaluated in vitro as a potential antagonist of fungal pathogens. Pseudomonas strains were tested against the causal agents of tomatoes damping-off (Sclerotinia sclerotiorum), root rot (Fusarium solani), and causal agents of stem canker and leaf blight (Alternaria alternata). For this purpose, dual culture antagonism assays were carried out on 25% tryptic soy agar, King B medium and potato dextrose agar to determine the effect of the strains on mycelial growth of the pathogens. In addition, strains were screened for their ability to produce exoenzymes and siderophores. All the strains significantly inhibited Alternaria alternata, particularly in 25% TSA medium. Antagonistic effect on Sclerotinia sclerotiorum and Fusarium solani was greater on King B medium. Protease was produced by 30% of the strains, but no strain produced cellulase or chitinase. Finally, the selected Pseudomonas strain, Psf5, was evaluated on tomato seedling development and as a potential candidate for controlling tomato damping-off caused by Sclerotinia sclerotiorum, under growth chamber conditions. In vivo studies resulted in significant increases in plant stand as well as in root dry weight. Psf5 was able to establish and survive in tomato plants rhizosphere after 40 days following the planting of bacterized seeds.     

Diagnostic de l’embolie pulmonaire chez la femme enceinte : apport de la scintigraphie. Étude rétrospective à propos de 116 cas

IntroductionPulmonary embolism during pregnancy is a leading cause of maternal mortality. The aim of our study was to evaluate pregnant women with suspected pulmonary embolism prevalence of lesions on the lung perfusion as well as the relationship between the parenchymal lesions and various clinical factors and biological risk.MethodsThis is a retrospective study of 116 pregnant patients referred for suspected pulmonary embolism. The median age was 30 years, ranging from 15 to 47 years and the median gestational term was 31 weeks with a range of 12 to 40 weeks. Suspicion of pulmonary embolism was established with the presence of clinical signs (dyspnea, chest pain and palpitations). No patient had received a chest radiograph. The patients underwent planar perfusion scintigraphy with injected activity of 40 to 50 MBq of macroaggregates of human albumin (MAA) labeled with 99mTc. The scintigraphic results were classified according to the PIOPED criteria, depending on the likelihood of EP. The scans with low or intermediate probability were included in the same group, that of indeterminate results.ResultsThe scan was positive (with high probability) in 16 patients (13.8%), normal in 78 patients (67.2%) and classified as inconclusive in 22 patients (18.9%). In 16 patients with a positive scan, the lesions were interested the left lung in 10 cases (62.5%), the right lung in 1 case (6.25%) and were bilateral in 5 cases (31.25%).ConclusionsIn cases of suspected pulmonary embolism in a pregnant woman, the choice of imaging technique depends on both its diagnostic value and also its adverse effects. Lung scintigraphy is the examination to be carried out first in pregnant women with a chest radiograph. In others, it is that angiography should be performed as first line.     

Analysis of δ-globin gene alleles in Tunisians: description of three new delta-thalassemia mutations

Molecular Biology Reports - Thalassemia is one of the most prevalent worldwide autosomal recessive disorders characterized by a great molecular and clinical expression heterogeneity. Alpha and...     

Chromosomal evaluation in a group of Tunisian patients with non-obstructive azoospermia and severe oligozoospermia attending a Tunisian cytogenetic department

Male infertility is the cause in half of all childless partnerships. Numerous factors contribute to male infertility, including chromosomal aberrations and gene defects. Few data exist regarding the association of these chromosomal aberrations with male infertility in Arab and North African populations. We therefore aimed to evaluate the frequency of chromosomal aberrations in a sample of 476 infertile men with non-obstructive azoospermia (n = 328) or severe oligozoospermia (n = 148) referred for routine cytogenetic analysis to the department of cytogenetics of the Pasteur Institute of Tunis. The overall incidence of chromosomal abnormalities was about 10.9%. Out of the 52 patients with abnormal cytogenetic findings, sex chromosome abnormalities were observed in 42 (80.7%) including Klinefelter syndrome in 37 (71%). Structural chromosome abnormalities involving autosomes (19.2%) and sex chromosomes were detected in 11 infertile men. Abnormal findings were more prevalent in the azoospermia group (14.02%) than in the severe oligozoospermia group (4.05%). The high frequency of chromosomal alterations in our series highlights the need for efficient genetic testing in infertile men, as results may help to determine the prognosis, as well as the choice of an assisted reproduction technique. Moreover, a genetic investigation could minimize the risk of transmitting genetic abnormalities to future generations.     

Effect of Crossbreeding on the Chemical Composition and Biological Characteristics of Tunisian New Olive Progenies

Olive fruit characteristics (weight, pulp/stone ratio, and oil and moisture content) and the iodine value (IV) of 31 new olive progenies (Olea europaea L.) were determined. To evaluate the effect of the genetic variability on these parameters, the new olive progenies, obtained through cross‐pollination between Tunisian and Mediterranean olive cultivars, were planted in a selected grove guaranteeing the homogeneity of the pedologic and climatic conditions. A strong genetic effect and significant differences between genotypes were obtained for the IV and the fruit characteristics evaluated. Discriminant analysis was used to classify the new progenies as distinct from each other, based on their IV, and their pulp and stone weight. An almost full discrimination of the olives from different genotypes was only achieved when the fruit characteristics (pulp and stone weight) and the IV data were analyzed together.     

Arbuscular mycorrhizal fungus <Emphasis Type="Italic">Rhizophagus irregularis</Emphasis> influences key physiological parameters of olive trees (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) and mineral nutrient profile

In this study, we hypothesized that colonization of olive trees (Olea europaea L.) with the arbuscular mycorrhizal fungus Rhizophagus irregularis could modify the profiles of rhizosphere microbial communities with subsequent effects on nutrient uptake that directly affects olive tree physiology and performance. In this context, a greenhouse experiment was carried out in order to study the effects of mycorrhizal colonization by R. irregularis on photosynthesis, pigment content, carbohydrate profile, and nutrient uptake in olive tree. After six months of growth, photosynthetic rate in mycorrhizal (M) plants was significantly higher than that of nonmycorrhizal plants. A sugar content analysis showed enhanced concentrations of mannitol, fructose, sucrose, raffinose, and trehalose in M roots. We also observed a significant increase in P, K, Ca, Mg, Zn, Fe, and Mn contents in leaves of the M plants. These results are important, since nutrient deficiency often occurs in Mediterranean semiarid ecosystems, where olive trees occupy a major place.     

Chemical Composition and Behavioral Effects of Five Plant Essential Oils on the Green Pea Aphid Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)

Essential oils (EOs) from Schinus molle, Helichrysum gymnocephalum, Cedrelopsis grevei and Melaleuca viridiflora, four aromatic and medicinal plants, are commonly used in folk medicine. EOs were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography‐flame ionization detection (GC‐FID); then evaluated for their behavioral effects on adults of the green pea aphid Acyrthosiphon pisum (Harris ) using a Perspex four‐armed olfactometer in order to test the compatibility of their use as phytoinsecticides to control this insect pest. Our results showed that the EOs from the leaves of S. molle, M. viridiflora and C. grevei did not change aphids’ behavior. However, S. molle fruits EO seemed to be attractive while H. gymnocephalum leaves EO exhibited repellency towards aphids at a dose of 10 μl. The major compounds in S. molle fruits EO were 6‐epi‐shyobunol (16.22%) and d ‐limonene (15.35%). While, in H. gymnocephalum leaves EO, 1,8‐cineole was the main compound (47.4%). The difference in aphids’ responses to these two EOs could be attributed to the differences in their compositions. Our findings suggest that these two EOs have potential applications for the integrated pest management of A. pisum (Harris ).     

An international supplier selection model with inventory and transportation management decisions

In this paper, we develop a mixed integer programming model for a supplier selection problem in an international context. The main features that characterize the international supplier selection are first identified. We show that when operating in an international context, the supplier selection process should consider the following issues: several buyers?? sites; inventory decisions, in particular the safety stocks that are held by buyers to cope with the delivery lead time uncertainty; inventory capacity constraints in buyers?? sites; selection of transportation modes, each having a specific delivery frequency and a transportation capacity; and multiple products and multiple time periods. Then, we propose a supplier selection model that takes into account such characteristics and that is suited for the international context. Finally, we solve the model with the commercial optimization software Cplex and we perform computational experiments based on a realistic case study from the automotive industry in order to prove the solvability and the usefulness of the model. Sensitivity analyzes are also performed for a number of model parameters.