Multiple biomarkers responses in Prochilodus lineatus allowed assessing changes in the water quality of Salado River basin (Santa Fe, Argentina)

This field study assessed water quality of Salado River basin by using a set of biomarkers in the fish Prochilodus lineatus. Multiple biomarkers were measured, including morphological indexes (condition factor, liver somatic index), hematological (red and white blood cells) and biochemical (glucose, total protein and cholinesterase activity) parameters. Besides, detoxication and oxidative stress markers (antioxidant enzymes, lipid peroxidation) were measured in liver, gills and kidney. Despite water quality assessment did not show marked differences among sites, biomarkers responses indicate that fish are living under stressful environmental conditions. According to multivariate analysis glucose, glutathione S-transferase activity, lipid peroxidation levels and the count of white blood cells are key biomarkers to contribute to discrimination of sites. So, we suggest use those biomarkers in future monitoring of freshwater aquatic systems.     

Contribution of a New PCR assay to the prenatal diagnosis of congenital toxoplasmosis

A polymerase chain reaction (PCR) assay has been developed for the detection of Toxoplasma gondii. The target sequence (88 bp) is part of a rDNA repetitive gene. A signal can be observed with only one parasite. It is directly and rapidly detected by electrophoresis and ethidium bromide staining. We report a prospective study of 80 documented cases of toxoplasmic seroconversions during pregnancy. The PCR assay of the amniotic fluids was compared with the current standard methods for diagnosis of fetal infection. Seventy specimens gave no PCR signal, and were negative according to prenatal tests and postnatal examinations. The presence of T. gondii was detected in ten specimens by PCR analysis. Four were confirmed by isolation of the parasite from the amniotic fluid; four by biological study of the fetal blood. For the remaining two, infection was diagnosed after birth. Together with ultrasonographic and biological data, this technique permits prenatal diagnosis within 1 day.     

Recovery of plasmatic cholinesterase activity in a neotropical fish Prochilodus lineatus (Pisces,Curimatidae) exposed to organophosphorous pesticides

The objective was to determine the plasmatic enzyme cholinesterase recovery, after being inhibited by an organophosphorous in juveniles of Prochilodus lineatus. Fish were exposed 12 h to a sublethal concentration of 1 mg/l of monocrotophos, and immediately placing in clean water during 12, 24, 48 and 96 h to detoxification. After this period, blood was extracted and plasma were used for the quantification of cholinesterase. The results showed a enzymatic inhibition of 91.9%, 55.1%, 50.4% and 33.4% with 12, 24, 48 and 96 h of recovery, respectively. The enzymatic activity spreads to be normalized with the course of hours and the degree of inhibition obtained initially was very high and sustained in the first 48 h.     

Integrated survey on toxic effects of lindane on neotropical fish: Corydoras paleatus and Jenynsia multidentata

We report the effect of lindane on fish experimentally exposed to lindane. Sublethal toxicity was assessed through (a) changes in histopathology; (b) the activity of GST in different organs; and (c) bioaccumulation in exposed fish. We present a survey on toxic effects of lindane at these three levels, proposing a sequence of dose-dependent effects. Physiological damage was reversible at lowest doses, but severe at the highest, including damage consistent with fibrosis in liver and karyolitic nucleus in brain of both studied species. Exposure of Jenynsia multidentata above 6 μg L⁻¹ caused activation a GST in liver and gills, followed by inhibition at 75 μg L⁻¹. Interestingly, the bioaccumulation rate was suddenly increased when GST was inhibited. Corydoras paleatus exposed to 6.0 μg L⁻¹ lindane did not present significant changes in GST activity; however, enzymatic inhibition was observed above 25 μg L⁻¹. The bioaccumulation rate in C. paleatus remained constant throughout the experiments. All in all, these results evidence that C. paleatus is more sensitive to lindane than J. multidentata.     

Laser cleaning of historical limestone buildings in Bordeaux appraisal using cathodoluminescence and electron paramagnetic resonance

BACKGROUND: Most historical buildings in Bordeaux city are made of limestone. This yellowish-white rock is rather porous and highly sensitive to pollution. As a consequence of local weathering conditions, these buildings present a dark appearance due to the development of a superficial dark grey to black crust. METHODS: For the last decade, a campaign has been underway to clean these buildings. Eleven techniques of surface treatment have been used, including laser beam technology. As a contribution to the study of laser beam effects on stone buildings, two analytical methods have been used on clean versus unclean surfaces: Cathodoluminescence (CL) and Electron Paramagnetic Resonance (EPR), in addition to SEM-EDX and XRD. RESULTS: The black crust is composed of different types of particles: carbon porous micro-particles of industrial origin, atmospheric dust due to the erosion of soils and rocks, alumino-silicate particles from urban pollution; all these particles being cemented by gypsum. DISCUSSION: As far as heritage conservation is concerned, the laser surface treatment not only preserves the original patina of the stone, but also leaves surface smoothness unaltered. CONCLUSIONS AND PERSPECTIVES: CL and EPR data confirm that lasers--with highly controlled parameters--only get rid of the black crust and, thus, reveal the underneath layer, the so-called patina. This patina shows no luminescence, whereas the limestone on which it has grown shows a bright orange emission of CL. This indicates CL to be a fast and easy way to provide a high quality control for the restoration of polluted ancient stones.     

Are Artificial Barrages Necessary to Prevent Saline Incursion? A Modelling Approach to Restore the Healthy Ecosystem of the Vembanad Lake

Environmental Modeling & Assessment - The Thanneermukkom Bund was constructed to prevent salt water intrusion in the low lying areas of the Kuttanad region which increase the paddy cultivation...