Use of blood parameters in fish to assess acidic stress and chloride pollution in French running waters

The study investigated whether plasmatic parameters in fish such as Cl- content could serve as physiological indicators to evaluate water quality. The variations of plasma Cl- content in two fish species caught in a wide range of rivers representative of the hydrographic system of Lorraine (N-E France) were investigated. First, we studied autochthonous populations of chub (Leuciscus cephalus) which is a widespread species in the rivers of Lorraine. Organisms living in highly mineralised rivers (>1500 microScm(-1))--either naturally or due to salt mine contamination--showed plasma Cl- content significantly greater than organisms living in river with a lower mineralisation. Second, we investigated plasma Cl- content of brown trout (Salmo trutta fario) in poorly mineralised streams (<80 microS cm(-1)) with different degrees of acidification, both on autochthonous and transferred organisms. While indigenous trout maintained their Cl- content even in the acidic streams, transferred trout exhibited an important decrease of Cl- content after 48 h of exposure under acidic conditions.     

Bacterivory of a mudflat nematode community under different environmental conditions

The fate of the benthic bacterial biomass is a topic of major importance in understanding how soft-bottom environments function. Because of their high abundance, production and nutritional value, benthic bacteria may constitute an important food resource for benthic fauna. The trophic role of bacteria for a nematode community on the Brouage mudflat (Marennes-Oléron-France), dominated by three species: Chromadora macrolaima (64% of the abundance), Daptonema oxycerca (15%) and Ptycholaimellus jacobi (8%), was determined in grazing experiments using ¹⁵N pre-enriched bacteria. On intertidal flats, seasonal, tidal and circadian cycles induce strong variations in environmental conditions. Grazing experiments were performed in order to measure the effects of abiotic (temperature, salinity and luminosity) and biotic (bacterial and algal abundances) factors on assimilation rates of bacteria by nematodes. In order to assess simultaneously bacteria and algal assimilation rates, algal abundances were modified adding ¹³C pre-enriched Navicula phyllepta. Assimilation rate was significantly lower at 5°C; moreover, general trend shows a prominent temperature effect with an optimum around 30°C. Assimilation at salinity 18 was not significantly different from the assimilation at salinity 31. Assimilation was higher under light conditions than in the dark. Above 10⁹ bacteria ml⁻¹, assimilation of bacteria remained unaffected by bacterial abundance. However, assimilation of algae increased with the algal concentration. Nematode kept feeding under conditions of stress, which are typical of the surficial sediment habitat and they appeared to be principally dependent on the algal resource.     

Treatment of domestic wastewater by an hydroponic NFT system

The objectives in this work were to investigate a conceptual layout for an inexpensive and simple system that would treat primary municipal wastewater to discharge standards. A commercial hydroponic system was adapted for this study and the wastewater was used to irrigate Datura innoxia plants. Influent and effluent samples were collected once a month for six months and analysed to determine the various parameters relating to the water quality. The legal discharge levels for total suspended, biochemical oxygen demand and chemical oxygen demand were reached with the plant system after 24 h of wastewater treatment. Total nitrogen and total phosphorus reduction were also obtained. NH4(+)-N was reduced by 93% with nitrification proving to be the predominant removal process. Significant nitrification occurred when the BOD5 level dropped 45 mg/l. Similar results were obtained for six months although the sewage composition varied widely. D. innoxia develops and uses the wastewater as the unique nutritive source.     

Analysis of a population of magnetotactic bacteria of the Gulf of Gabès,Tunisia

The occurrence of magnetotactic bacteria (MTB) on a Tunisian marine coast exposed to heavy metals pollution (Sfax, Gulf of Gabès, Mediterranean Sea) was investigated. The MTB population of this Southern Mediterranean coast was compared to the MTB populations previously investigated on the French Northern Mediterranean coast. A dominant MTB coccus morphotype was observed by microscopy analysis. By pyrosequencing technology, the analysis of the 16S ribosomal RNA (rDNA) revealed as much as 33 operational taxonomic sequence units (OTUs) close to sequences of MTB accessible in the databases. The majority were close to MTB sequences of the “Med group” of α-Proteobacteria. Among them, a dominant OTU_001 (99 % of the MTB sequences) affiliated within the Magnetococcales order was highlighted. Investigating the capacities of this novel bacterium to be used in bioremediation and/or depollution processes could be envisaged.     

Portal absorption of 14C after ingestion of spiked milk with 14C-phenanthrene, 14C-benzo[a]pyrene or 14C-TCDD in growing pigs

Polycyclic aromatic hydrocarbons (PAHs) and dioxins are lipophilic organic pollutants occurring widely in the terrestrial environment. In order to study the PAHs and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) transfer in the food chain, pigs have been fed with milk mixed either with 14C-phenanthrene, with 14C-benzo[a]pyrene or with 14C-TCDD. The analysis of portal and arterial blood radioactivity showed that both PAHs and TCDD were absorbed with a maximum concentration at 4-6 h after milk ingestion. Then, the blood radioactivity decreased to reach background levels 24 h after milk ingestion. Furthermore, the portal and arterial blood radioactivities were higher for phenanthrene (even if the injected load was the lowest) than these of benzo[a]pyrene or these of TCDD, in agreement with their lipophilicity and water solubility difference. Main 14C absorption occurred during the 1-3 h time period after ingestion for 14C-phenanthrene and during the 3-6 h time period for 14C-benzo[a]pyrene and for 14C-TCDD. 14C portal absorption rate was high for 14C-phenanthrene (95%), it was close to 33% for 14C-benzo[a]pyrene and very low for 14C-TCDD (9%). These results indicate that the three studied molecules have a quite different behaviour during digestion and absorption. Phenanthrene is greatly absorbed and its absorption occurs via the blood system, whereas benzo[a]pyrene and TCDD are partly and weakly absorbed respectively. However these two molecules are mainly absorbed via the portal vein.     

Screening for fetal Down syndrome with maternal serum hCG and oestriol: A prospective study

We report the preliminary results of a prospective study aimed at evaluating the effectiveness of Down syndrome (DS) screening using second-trimester measurement of maternal serum human chorionic gonadotrophin (hCG) and unconjugated oestriol (uE3) together with maternal age. Reference values for hCG, uE3, and the hCG/uE3 ratio in normal pregnancies were established from more than 3000 normal gestations and found to follow a log-normal statistical distribution. Risk evaluation was made using reference values for affected pregnancies from retrospective studies. Screening of 10 000 women under 38 years resulted in 412 amniocenteses and the prenatal diagosis of six cases of DS, whereas four cases remained undetected until term. In a parallel study, diagnostic amniocentesis was performed in women over 38 years and in women with a previous affected child, and an evaluation of the risk of fetal DS based on serum hCG and uE3 levels was made in all cases. Fourteen cases of DS were detected. Median values for hCG and uE3 in the 24 affected pregnancies were close to the 90th and tenth centiles of the normal reference values, respectively, and thus are in good agreement with the values reported by others in retrospective studies.