Chronic toxicity of acetone in the fresh water snail Lymnea stagnalis.

With water of total hardness of 230 mg/l of CaCO3 all the tried concentrations (0.1, 0.2, 0.4 and 0.6%) of acetone induced a decrease in the growth of the young pond snails. For older snails, a 0.4% concentration was the threshold at which an inhibitory effect of the shell growth was observed. From the 0.1% concentration a decrease in the shell mineralization was recorded. In the range of 0.1--0.6% concentrations, the decrease of the fecundity varied from 3% to 31%. At lowest concentrations, only the number of egg-masses/snail was reduced. At the 0.6% level a lower number of eggs/egg-mass was added. The 0.6% concentration of acetone disturbed only the fertility of the eggs; lowest concentrations significantly increased the frequency of polyembryony.

PERMANENT GENETIC RESOURCES: Isolation of 60 polymorphic microsatellite loci in EST libraries of four sibling species of the phytopathogenic fungal complex Microbotryum.

We report the development of 60 microsatellite markers on four species of the fungal complex Microbotryum, causing anther smut of the Caryophyllaceae. Microsatellites were found in four expressed sequence tag (EST) libraries, built from isolates of M. lychnis-dioicae, M. violaceum sensus stricto, M. lagerheimii and M. dianthorum, collected, respectively, from the plants Silene latifolia, S. nutans, S. vulgaris and Dianthus carthusianorum. Intrapopulation polymorphism was investigated using 24 isolates, and cross-amplification was explored using 23 isolates belonging to at least 10 different Microbotryum species. This study provides numerous microsatellite markers for population genetics and mapping studies.

Common sex-linked deleterious alleles in a plant parasitic fungus alter infection success but show no pleiotropic advantage.

Microbotryum violaceum is a fungus that causes the sterilizing anther smut disease in Caryophyllaceae. Its diploid teliospores normally produce equal proportions of haploid sporidia of its two mating types. However natural populations contain high frequencies of individuals producing sporidia of only one mating type ('biased strains'). This mating type-ratio bias is caused by deleterious alleles at haploid phase ('haplo-lethals') linked to the mating type locus that can be transmitted only by intra-tetrad selfing. We used experimental inoculations to test some of the hypotheses proposed to explain the maintenance of haplo-lethals. We found a disadvantage of biased strains in infection ability and high intra-tetrad mating rates. Biased strains had no higher competitive ability nor shorter latency and their higher spore production per flower appeared insufficient to compensate their disadvantages. These findings were only consistent with the hypothesis that haplo-lethals are maintained under a metapopulation structure because of high intra-tetrad selfing rates, founder effects and selection at the population level.

Organochlorine residues in european eel (Anguilla anguilla), crucian carp (Carassius carassius) and catfish (Ictalurus nebulosus) from Vaccarès lagoon (French National Nature Reserve of Camargue) - effects on some physiological parameters.

European eels (Anguilla anguilla), crucian carps (Carassius carassius) and catfish (Ictalurus nebulosus) were collected in three coastal locations of the Vaccarès lagoon (French National Nature Reserve of Camargue). The purpose of this paper is to report results of the first biomonitoring investigation in fish living in this protected coastal wetland. Residues of organochlorine (OC) contaminants (i.e. SigmaPCBs, gammaHCH, HCB, dieldrin, pp'-DDE) were determined in hepatic and muscular tissues, in order to compare geographical and seasonal distribution. Total exposure levels appeared to be more important in fatty fish such as eels than in crucian carps and catfish. The highest OC concentrations in liver (SigmaPCB) and in muscle (gammaHCH) were detected in Spring in some fish coming from a site located near the mouth of a canal draining irrigation waters of rice fields. Morphophysiological parameters (condition factor, organo-somatic indexes and lipid tissue composition) were measured concomitantly. Correlations between the hepatic and muscular burdens of OC and condition factor or organo somatic indexes were infrequent and rather negative. Localization of lipid accumulation (neutral or polar lipids) depended on metabolic rates of different species and appeared related to the fish trophic level.

Outdoor experimental ponds (mesocosms) designed for long-term ecotoxicological studies in aquatic environment.

Outdoor artificial ponds (mesocosms) of 12 m3 were designed for long-term ecotoxicological studies. Sediment, macrophytes (Typha angustifolia and Elodea canadensis), and free and caged freshwater snails [Lymnaea palustris (Müller)] and wood lice (Asellus aquaticus L.) were collected in nearby natural ecosystems and introduced in the mesocosms. Sixty goldfish (Carassius auratus L.) were caged in each pond. Introduced species developed and reproduced in every mesocosm. Animal species (mainly insects and amphibians) spontaneously colonized the ponds, developed, and reproduced. The resulting communities qualitatively resemble those living in natural lentic systems in the surrounding area. Homogenity in physical and chemical conditions and in abundance of phytoplanktonic, periphytic, and macroinvertebrate communities between the different mesocosms was assessed during the stabilization period (8 months). Except for periphyton biomass, no divergent evolution was observed between the ponds. Mesocosm water was slightly eutrophic, alkaline (mean pH: 8.47 +/- 0.09), and moderately hard and mineralized. The homogenous and realistic environmental conditions and high ecological representativity of the outdoor experimental ponds were suitable for extensive ecotoxicological studies. Considerations on the choice and origin of introduced species and on possible interactive effects of the transfer of organisms from natural environments, maintainance conditions, and pollutant exposure are discussed.