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We report an improvement of a one-step reverse transcription polymerase chain reaction (RT-PCR) assay for the detection of Citrus psorosis virus (CPsV; genus Ophiovirus) in citrus trees. Two different sample preparation procedures were compared. The data showed that when using total RNA extracted by the Qiagen procedure more virus isolates could be detected compared with the Trizol procedure. Three pairs of primers reported in literature and selected within the coat protein (CP) region of the virus were used for a reliable detection of CPsV. Only one primer pair has been able to detect all CPsV isolates collected from different citrus regions of Morocco. In addition, this report showed that one-step RT-PCR was more sensitive and more consistent than ELISA test. Notably, 15 out of 22 samples tested positive by one-step RT-PCR could not be detected by Mab Ps29, thus providing a degree of differentiation among isolates. The detection protocol described in this study could be used in citrus certification programs and to test trees in nurseries and commercial orchards for CPsV infection.

The functioning of karst systems in the Tlemcen Mountains, Algeria, was studied using environmental isotopic and chemical parameters. The weakly enriched values of 18O suggest a fast infiltration of water through the karst systems. The deuterium (2H) excess in groundwater and tritium (3H) in precipitation show that the region is subjected to Mediterranean and Atlantic influences with a predominance of the former. The isotopic gradient, in combination with topographic and geologic criteria, allows the recharge areas of the main karst systems to be estimated. The results of 13C, 14C and 3H analysis show that the majority of present waters come from perched systems and mixture waters influenced by three clusters (“ante-thermonuclear” waters, “thermonuclear” waters, and present waters) that generally emerge from semi-confined systems. The oldest waters are relatively rare and are stored in deeply confined systems. These results are consistent with the hydrochemical and the hydrogeological findings. The results have important implications in groundwater protection.

In this paper we will present the family of Newton algorithms. From the computer algebra point of view, the most basic of them is well known for the local analysis of plane algebraic curves f(x,y)=0 and consists in expanding y as Puiseux series in the variable x. A similar algorithm has been developped for multi-variate algebraic equations and for linear differential equations, using the same basic tools: a “regular” case, associated with a “simple” class of solutions, and a “simple” method of calculus of these solutions; a Newton polygon; changes of variable of type ramification; changes of unknown function of two types y=ctμ+ϕ or y=exp (c/tμ)ϕ.