Differential fungal colonization and physiological defense responses of new olive cultivars infected by the necrotrophic fungus <Emphasis Type="Italic">Verticillium dahliae</Emphasis>

New olive cultivars adapted to Tunisia’s growing conditions were examined for their resistance to verticillium wilt (VWO) to determine whether differences in susceptibility among currently grown cultivars might contribute to the management of this disease. Based on the evaluation of 14 cultivars, 10 were classified as susceptible or extremely susceptible (Chetoui, Chemlali, Rkhami, Jarboui, Zalmati, Jarboui, Oueslati, Manzanille, Picholine and Frangivento), 2 as moderately susceptible (Koroneiki and Coratina), and 2 as resistant (Meski and Sayali) to VWO. Three cultivars with different susceptibility levels were selected to examine the levels of hydrogen peroxide (H₂O₂), soluble sugars (SS), soluble proteins (SP), total polyphenols (TP), lipid peroxidation, activities of antioxidant enzymes, and fungal biomass in planta. V. dahliae DNA occurred early in the roots at 15 dpi and reached a maximum of 3.507 and 2.52 ng/100 ng of plant DNA, respectively, in the extremely susceptible and resistant cultivars. Fungal DNA in the stems occurred at 30 dpi and increased slowly to reach a maximum of 0.23 ng/100 ng of total DNA in the extremely susceptible cultivars. We showed that the amount of fungal DNA in planta was roughly correlated with the susceptibility to VWO (P < 0.0001; r = 0.95). The comparison of cultivars at the physiological level indicated that olive resistance is roughly correlated with the antioxidant enzymes activity, H₂O₂ concentration, and TP and SP contents. The results of this study open new perspectives for olive genetic improvement programs aiming at developing new cultivars resistant to this wilt.     

A novel <Emphasis Type="Italic">CASR</Emphasis> mutation in a Tunisian FHH/NSHPT family associated with a mental retardation

The calcium-sensing receptor (CASR), a plasma membrane G-protein coupled receptor, is expressed in parathyroid gland and kidney, and controls systemic calcium homeostasis. Inactivating CASR mutations have previously been identified in patients with familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT). The aim of the present study is to determine the underlying molecular defect of FHH/NSHPT disease in a consanguineous Tunisian family. Mutation screening was carried out using RFLP-PCR and direct sequencing. We found that the proband is homozygous for a novel 15 bp deletion in the exon 7 (c.1952_1966del) confirming the diagnosis of NSHPT. All the FHH members were found to be heterozygous for the novel detected mutation. The mutation, p.S651_L655del, leads to the deletion of 5 codons in the second trans-membrane domain of the CASR which is thought to be involved in the processes of ligand-induced signaling. This alteration was associated with the evidence of mental retardation in the FHH carriers and appears to be a novel inactivating mutation in the CASR gene. Our findings provide additional support for the implication of CASR gene in the FHH/NSHPT pathogenesis.     

A novel MT-CO1 m.6498C>A variation associated with the m.7444G>A mutation in the mitochondrial COI/tRNASer(UCN) genes in a patient with hearing impairment,diabetes and congenital visual loss

Mitochondrial diseases are a clinically heterogeneous group of disorders that arise as a result of dysfunction of the mitochondrial respiratory chain. Sensorineural hearing loss (SNHL) has been described in association to different mitochondrial multisystem syndromes, often involving the central nervous system, neuromuscular, or endocrine organs. In this study, we described a Tunisian young girl with hearing impairment, congenital visual loss and maternally inherited diabetes. No mutation was found in the mitochondrial tRNA^Leu(UUR) and the 12S rRNA genes. However, we detected the m.7444G>A mutation in the mitochondrial COI/tRNA^Ser(UCN) genes. This mutation eliminates the termination codon of the MT-CO1 gene and extends the COI polypeptide by three amino acids (Lys–Gln–Lys) to the C-terminal. The whole mitochondrial genome screening revealed the presence of a novel mutation m.6498C>A (L199I) in the mitochondrial DNA-encoded subunit I of the cytochrome c oxidase (COX). This “probably damaging” transversion affects a highly conserved domain and it was absent in 200 Tunisian controls. The studied patient was classified under the haplogroup H2a.     

Influence of freezing stress on morphological alteration and biofilm formation by Listeria monocytogenes: relationship with cell surface hydrophobicity and membrane fluidity

The morphological changes and adhesive property of three Listeria monocytogenes strains submitted to freezing stress (?20 °C) were studied. The atomic force micrographs showed a reduction in the cell size and an evolution to coccoid shape. The phenotypic slime production of L. monocytogenes and the expression of the adhesive gene were investigated before and after 10 months of incubation in salmon at ?20°. Our results showed that after ten months, stressed stains become more adherent and able to produce slime. In addition, we noted that this pathogen presents same physiological changes to adapt to starvation conditions. The cellular fatty acids composition of adhered and floating cells of three L. monocytogenes strains was taken into consideration. The stressed strains presented different chain lengths and therefore an increase in the hydrophobicity level. Moreover, we noted that the adhesive property of L. monocytogenes strains affects the Benzalkonium chloride bacterial sensitivity which increased after biofilm formation.     

Neural network approach to reference evapotranspiration modeling from limited climatic data in arid regions

In order to better manage the limited water resources in arid regions, accurate determination of plant water requirements is necessary. For that, the evaluation of reference evapotranspiration (ET0)--a basic component of the hydrological cycle--is essential. In this context, the Penman Monteith equation, known for its accuracy, requires a high number of climatic parameters that are not always fully available from most meteorological stations. Our study examines the effectiveness of the use of artificial neural networks (ANN) for the evaluation of ET0 using incomplete meteorological parameters. These neural networks use daily climatic data (temperature, relative humidity, wind speed and the insolation duration) as inputs, and ET0 values estimated by the Penman-Monteith formula as outputs. The results show that the proper choice of neural network architecture allows not only error minimization but also maximizes the relationship between the dependent variable and the independent variables. In fact, with a network of two hidden layers and eight neurons per layer, we obtained, during the test phase, values of 1, 1 and 0.01 for the determination coefficient, the criterion of Nash and the mean square error, respectively. Comparing results between multiple linear regression and the neural method revealed the good modeling quality and high performance of the latter, due to the possibility of improving performance criteria. In this work, we considered correlations between input variables that improve the accuracy of the model and do not pose problems of multi-collinearity. Furthermore, we succeeded in avoiding overfitting and could generalize the model for other similar areas.     

Sequential events of apoptosis induced by zearalenone in cultured hepatocarcinoma cells

Zearalenone (ZEA) is a fungal metabolite that can contaminate feed and foodstuffs and can cause serious health problems for animals as well as for humans. The present investigation was conducted to determine the chronological succession of the main events that characterise ZEA-induced toxicity in human hepatocarcinoma cells. To this aim, we have monitored the effects of ZEA on (1) cell viability, (2) heat-shock protein expression, (3) oxidative damage, (4) DNA fragmentation, (5) the cell cycle and (6) the cell-death-signalling pathway. Our results demonstrated that ZEA reduced cell viability in a time- and dose-dependent manner. When we exposed HepG2 cells to 100 μM ZEA (80% of cells are viable) for different treatment times (2, 4, 8, 24, 30, 48 and 60 h), we demonstrated an induction of Hsp70 protein, an increase in reactive oxygen species (ROS) generation, DNA fragmentation and cell-cycle arrest. These events begin after only 2 h of mycotoxin exposure and are earlier than those implicated in the execution of apoptosis. However, significant apoptotic cell death was observed after at least 30 h of ZEA exposure as a consequence of increased Bax expression, decreased Bcl-2 expression and mitochondrial membrane potential (Δψm)-released cytochrome c and activated caspase-3 and caspase-9.     

Olive mill wastewater disposal in evaporation ponds in Sfax (Tunisia): moisture content effect on microbiological and physical chemical parameters

The study of the isotherms desorption of olive mill wastewater (OMW) was investigated to describe its water activity under different saturated environments. The microbial biodegradation of OMW during its storage in 5 evaporation ponds located in Agareb (Sfax-Tunisia) was carried out during the oil-harvesting year held 105 days in 2004. Gravimetric static method using saturated salt solutions was used and OMW as placed at 30°C and under different water activities ranging from 0.11 to 0.90. Eight models were taken from the literature to describe experimental desorption isotherms. During storage, the evolution of physico-chemical parameters including pH, temperature, evaporation, humidity, total phosphorus, chemical oxygen demand (COD), biological oxygen demand (BOD) and phenols and three microbiological flora (aerobic mesophilic bacteria, yeasts and moulds) were considered. At 30°C, when relative humidity increased in the experimented ponds of 69, 84 and 90%, the evaporation speed decreased from 1.24 × 10⁻⁵ to 5 × 10⁻⁶ cm³ s⁻¹, from 6 × 10⁻⁵ to 7 × 10⁻⁶ cm³ s⁻¹ and from 5 × 10⁻⁶ to 1.1 × 10⁻⁷ cm³ s⁻¹ respectively. The desorption isotherm exhibited a sigmoidal curve corresponding to type II, typical of many organic material. The GAB and Peleg models gave the best fit for describing the relationship between the equilibrium moisture content and water activity in OMW (R ² = 0.998). During the storage period, the analysis showed an increase of all the physico-chemical parameters studied, except phenols and total phosphorus concentrations. The microbiological study showed the predominance of yeasts and moulds and the decrease of bacteria population after 75 days reflecting both effect of recalcitrant compounds and the water activity on microbial growth.     

Identification of genetic defects underlying FVII deficiency in 10 patients belonging to eight unrelated families of the North provinces from Tunisia

ABSTRACT: Inherited factor VII (FVII) deficiency is a rare disorder characterized by a bleeding phenotype varying from mild to severe. To date, more than 200 mutations have been described along the F7 gene encoding for FVII. The aim of this study was the identification of genetic defects underlying FVII deficiency in 10 patients belonging to eight unrelated families of the North provinces from Tunisia. Mutation detection was performed by sequencing the whole F7 gene coding region, exon-intron boundaries and about 400 bp of the promoter region. We identified 5 mutations in five unrelated families; the novel p.F328Y mutation and the reported mutations: p.R304Q, p.M298I, IVS1aG > A and nt1005C > T. For the remaining 5 patients we didn't identified any mutations using PCR/Sequencing protocol. In conclusion, this study represents the first comprehensive molecular series of FVII deficiency affected patients in Tunisia from the North. We will try in the future to continue the molecular study for Tunisian patients from Center and South provinces in order to have a complete idea about the FVII deficiency mutational profile in our country. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1288044089753085.