Effect of microbial seeding of crude oil in seawater in a model system

The adding of a mixed culture of marine hydrocarbon-degrading bacteria to petroleum polluted seawater did not increase the hydrocarbon degradation capability of the water. All the strains of the mixed culture disappeared from the dominant microflora while the autochthonous bacteria showed a capacity for adaptation to petroleum degradation about four days after the oil spill. This confirms the advantage of natural bacterial communities. The oil spilled on the sea surface evolved very quickly under the influence of abiotic factors such as sunlight. Aromatic petroleum fractions were oxidized and polymerized. This chemical evolution causes a drastic decrease of the biodegradability of crude oil.     

Feeding ecology ofLeitoscoloplos fragilis

The present study examines the effects of density ofLeitoscoloplos fragilis and of fine sediment on benthic microalgal abundance and production in laboratory microcosms, and the effects of fine sediment on diffusive transport of ammonia. Microcosms having different densities ofLeitoscoloplos fragilis (Verrill, 1873) were determined in sediment collected from one of two field stations (each containing a different amount of fine particles <125 m) from Cape Henlopen, Delaware, USA, in August 1986. The worms were acclimated in a recirculating seawater system for two months prior to experiments. Chlorophylla concentrations were highest in sediments with less fine particles (<125 m). Benthic diatom production, total microbenthic metabolic activity, and concentrations of pore-water ammonia were higher in sediment microcosms containing high densities of worms.L. fragilis grew more in microcosms containing less fine particles and higher worm densities. The upward flux of ammonia across the sediment-water interface was higher in sediments with less fine particles. A greater abundance of fine particles in these sediments impedes the upward flux of ammonia to surface and nearsurface diatoms. The coupling between population density and diatom production, which can be altered by fine-particle abundance could control the distribution and stability of populations ofL. fragilis.     

The effects of heavy metal contamination on the soil arthropod community of a shooting range

Soils in clay pigeon shooting ranges can be seriously contaminated by heavy metals. The pellets contained in ammunition are composed of Pb, Sb, Ni, Zn, Mn and Cu. The total concentrations of these metals in soils, and the effects of their increasing levels on the arthropod community were investigated at seven sampling sites in a clay pigeon shooting range and compared with two controls. Research revealed that the spatial distribution of Pb and Sb contamination in the shot-fall area was strongly correlated with the flight path of the pellets. Ordination obtained through Redundance Analysis showed that Collembola, Protura and Diplura were positively correlated with major detected contaminants (Pb, Sb), while Symphyla showed a negative correlation with these pollutants. Determination of the soluble lead fraction in soil, and of its bioaccumulation in the saprophagous Armadillidium sordidum (Isopoda) and the predator Ocypus olens (Coleoptera), showed that a significant portion of metallic Pb from spent pellets is bioavailable in the soil and can be bioaccumulated by edaphic organisms, entering the soil trophic network, but without biomagnification.     

Biomass measurements and weight-to-weight conversion factors: a comparison of methods applied to the mussel Mytilus galloprovincialis

Wet weight to ash-free dry weight conversion factors were calculated for the bivalve Mytilus galloprovincialis Lamarck; specimens were collected in November 1989 in the Magra Estuary (eastern Ligurian Sea, Italy). Ash-free dry weight was determined by four different methods: (A) mechanical separation of shell and body; (B) shell dissolution with HCl; (C) dissolution of organic matter with NaClO; (D) incineration of the whole organism. The results obtained by these four methods were significantly different, indicating that caution is necessary when comparing biomass data obtained by different methods. Incineration and decalcification with HCl seem to be the best procedures: they not only combine accuracy with speed, but are also the most universally applicable, being equally suitable for soft-bodied or hard-bodied organisms. Mechanical separation can lead to an underestimation of the biomass, whereas treatment with NaClO can lead to its overestimation. However, no method can be considered the best in absolute terms, the final choice depending on the particular weight measurement required (e.g. shell-free dry weight) and the nature of the organism concerned (e.g. an organism with a large carbonate content).     

Demonstration of spontaneously dividing male fetal cells in maternal blood by negative magnetic cell sorting and fish

We investigated a case of massive feto-maternal bleeding by using negative magnetic cell sorting (MACS) and fluorescent in situ hybridization (FISH). A 37-year-old pregnant woman had an uncomplicated amniocentesis for advanced maternal age at 16 weeks' gestation. The fetal karyotype was 46, XY. At 19 weeks' gestation, she had a minor car accident and slight vaginal bleeding. A subsequent Kleihauer-Betke test showed a 140 ml feto-maternal haemorrhage. Serial sonographic examinations indicated a normal fetus and placenta. We performed FISH analysis on maternal peripheral blood at 25 weeks. Anti-CD45 and MACS were used to deplete maternal leucocytes, enriching the proportion of fetal nucleated erythrocytes present. The isolated cells were analysed by using dual-colour FISH with X and Y specific probes. Approximately 65 800 nucleated cells were obtained after MACS depletion. A total of 234 cells were analysed by FISH. The results revealed that 70 of the nucleated cells (30 per cent) were male with one X and one Y signal. Among these cells, six male metaphases were observed in spontaneously dividing cells.