Diagnosis and molecular analysis of Potato leafroll virus isolates in Tunisia

Potato leafroll virus (PLRV) is a major constraint to potato production in North Africa. Serological (sandwich and cocktail ELISA) and molecular (RT-PCR) tests were used to detect PLRV in 131 potato samples collected in different areas of Tunisia. RT-PCR proved to be usable as a routine diagnostic test for epidemiological purposes, being more sensitive and reliable, and less time-consuming, than serological tests. One RT-PCR-amplified portion of ORF3 (336 nt) was cloned and sequenced, and used for molecular characterization of Tunisian PLRV isolates. These showed high sequence identity with PLRV retrieved from GenBank.     

Possible correlations between the characteristics of Potato leafroll virus isolates occurring in different geographical regions in Tunisia

Biological and molecular characterization supported by transmission efficiency, symptom expression and Open Reading Frame 0 (ORF0) nucleotide sequence analysis were carried out to assess nine isolates of Potato leafroll virus (PLRV) collected from three Tunisian geographic and bioclimatic zones. Plant-to-plant transmission by Tunisian Myzus persicae aphid clones showed high transmission efficiency for all isolates tested. Symptom expression analysis on a Physalis floridana plant test distinguished viral isolates as very severe, severe and mild. The ORF0 sequences of the Tunisian PLRV isolates showed an assignment to two aggregates when compared with GenBank PLRV sequences. A significant correlation between symptom severity and ORF0 nucleotide sequence or between symptom severity and geographic origins of the PLRV isolates was established. However, the transmission efficiency and the ORF0 sequence were not affected by the bioclimatic origin. No significant correlation between transmission and symptom or between transmission and the ORF0 sequence was detected.     

Designing crop management systems by simulation

To help agricultural advisors to propose innovative crop management systems, simulation models can be a complementary tool to field experiments and prototyping. Crop management systems can be modelled either by using a vector representing dates and quantities used as input parameters in crop models or by developing specific decision models linked with biophysical models. The general design process of crop management systems by simulation follows a four-step loop (GSEC): (i) generation; (ii) simulation; (iii) evaluation; (iv) comparison and choice. The Generation step can follow different approaches: from blind generation before simulation to optimization procedures using artificial intelligence algorithms during the loop process. Simulation is mainly an engineering problem. Evaluation process means assigning a vector of indicators to the simulated crop management systems. A three-point evaluation can be carried out on the simulated crop management systems: global, agronomic and analytical. Comparison and choice of different simulated crop management systems raise the question of “monetary” versus “non-monetary” comparison and how to aggregate different quantities such as drainage, nitrogen fertilisers, labour, etc. Different examples are given to illustrate the GSEC loop on the basis of research programs conducted in France. Methodological advances and challenges are then discussed.     

Aetiological factors and perception of anaemia in Tunisian women of reproductive age

OBJECTIVES: To identify aetiological factors in anaemia and to explore knowledge, perceptions and attitudes towards anaemia. DESIGN: Two cross-sectional surveys and sixteen focus group discussions. SETTING: The two regions with the highest prevalence of anaemia in Tunisia, Greater Tunis (GT) and the South West (SW). SUBJECTS: Two representative samples of 687 (GT) and 729 (SW) women of reproductive age; 108 women were included in focus group discussions. RESULTS: Among anaemic women, 63.4% in the GT region and 80.2% in the SW displayed iron deficiency (ID). Genetic haemoglobinopathies accounted for 10.0% and 3.6% of the cases of anaemia in the two regions, respectively. After adjustment for confounders, the major factors for iron-deficiency anaemia were low dietary Fe intake (OR = 5.0, 95% CI 3.0, 8.4), drinking tea after eating (OR = 3.4, 95% CI 2.0, 5.7) and pica (OR = 2.1, 95% CI 1.1, 3.9). Most of the women related anaemia to the following causes: malnutrition, lack of hygiene, and their heavy workload and responsibilities in the household. Many women connected anaemia with hypotension. Few established a relationship between ID and anaemia. They had confidence in their doctor for treatment, but many complained they were not given sufficient information. Low dietary Fe intake, inappropriate food practices and inadequate perceptions contribute to the aetiology of anaemia in women. CONCLUSIONS: These results point out to the need for a strategy combining food fortification, Fe supplementation for pregnant women, nutritional education for the general public and at-risk specific target groups, and training of health professionals.     

ZINC TREATMENT RESULTS IN TRANSPIRATION RATE DECREASES THAT VARY AMONG SOYBEAN GENOTYPES

Zinc (Zn) pollution of croplands can have negative impacts on yields through its effects on key physiological functions such as transpiration rate (TR). Previous long-term experiments indicated that differential tolerance among soybean genotypes following exposure to high Zn levels existed in the shoots. There are, however, no studies of the possibility that short-term responses to Zn directly limit shoot TR. Measurements of TR of eight soybean genotypes were measured over 220 minutes after placing de-rooted shoots in 500 μM Zn solution. Six genotypes exhibited TR that decreased slowly in a linear fashion over time while two genotypes (‘PI 416937’ and ‘N01-11136’) exhibited very rapid decrease in TR following a Boltzmann sigmoid response. One possibility to explain these results is that there exists a Zn-sensitive AQP population in the leaves of ‘PI 416937’ and ‘N01-11136’ with abundance or activity that is much higher than in the leaves of the remaining six lines.     

Use of amino-modified cotton fibers loaded with copper ions for anionic dye removal under batch and fixed-bed systems: A comparative study

Amine-functionalized supports were prepared by chemical modification of cotton fibers using amino compounds namely diethylenetriamine (DET) and 1,4-diaminobutane (DB) in order to be loaded with copper ions. Evidence of attaching amine groups onto cellulosic fibers was confirmed through nitrogen and SEM analysis. Adsorption behavior of Acid Blue 25 from aqueous solutions onto [Cu(II)/DET-cotton] and [Cu(II)/DB-cotton] has been evaluated via batch and column mode systems. During the batch experiments, the effects of temperature and type of adsorbent on dye removal were investigated. Results revealed the formation of ternary complexes of the type [AB25/Cu(II)/adsorbent] with a [5/2:3:1] stoichiometry for DET-cotton and a [1:1:1] stoichiometry for DB-cotton at 20 °C. In the isotherm studies, Langmuir, Freundlich, and Jossens equations were applied and it was found that the experimental data conformed to Jossens model. Thermodynamic parameters such as change in free energy (ΔG ⁰), enthalpy (ΔH ⁰), and entropy (ΔS ⁰) have also been calculated in this paper, and it was found that the adsorption process was exothermic and spontaneous. The column experiments were conducted to study the effect of bed height on adsorption performance of both adsorbents. Results exhibited that the column capacity of [Cu(II)/DET-cotton] complex was found to be higher than that of [Cu(II)/DB-cotton] as was obtained in batch process. BDST model was applied to experimental data in order to predict the breakthrough curves and determine the characteristics parameters of the column useful for process design. Results revealed that the used model was appropriate to fit the experimental data. Desorption studies to recover the adsorbed dye from both adsorbents were performed with NaOH and NH₄Cl solutions.     

Drying morphologies and emport rate effect on wetting and spreading behaviours

The main idea of this work is to study the different phenomena of spreading, evaporation, and diffusion that bound to the ink-jet printing. The coating film is studied as well as its drying morphologies and its wetting behavior. Then the drop water spreading on coated fabric is investigated. At that time spreading kinetic is characterized by the digidrop 3S which permits to measure precisely the various parameters such as contact angle, diameter, height, volume and drop profile in contact with the support during wetting phenomenon. This survey shows, on the one hand, that the coating film structure is deeply affected by drying morphologies. On the other hand, drying conditions influence different parameters of kinetic drop spreading on virgin glass and cotton material. Then the increasing of coating film thickness encourages the drop spreading.     

Assessment of magnesium chloride as an anaesthetic for adult sea urchins (Paracentrotus lividus): incidence on mortality and spawning

During this study different concentrations of magnesium chloride (MgCl₂) were tested on adult wild‐caught sea urchins (Paracentrotus lividus) immediately after their collection in the field in order to assess whether MgCl₂ can act as an anaesthetic during their transport and prevent unplanned spawning. Such accidental spawning is a stress response associated with transport of this species. The mortality and gonadal indices were recorded after a 1‐h submersion in different strength solutions of MgCl₂ (5, 20, 40, 80 and 100 mmol L⁻¹ MgCl₂), followed by 5 h of dry transport under two different temperatures (19 and 25 °C). The effective concentration of MgCl₂ was defined as one that does not induce mortality and gonad mass loss following sea urchin transport and laboratory conditioning. Treatment of sea urchins with 5 mmol L⁻¹ MgCl₂ prevented mortality and unplanned spawning; however, elevated concentrations of magnesium (40, 80 and 100 mM) were toxic to sea urchins, inducing a massive mortality and gonad mass decrease during the acclimatization period, essentially when sea urchins were transported under an elevated temperature (25 °C). It is concluded that MgCl₂ is a suitable non‐toxic anaesthetic, easily available for adult sea urchins (P. lividus) when it is used at its optimal anaesthetizing concentration.