Swedish survey on extra structurally abnormal chromosomes in 39 105 consecutive prenatal diagnoses: Prevalence and characterization by fluorescence in situ hybridization

During 7 years (1985–1992), 39 105 consecutive prenatal diagnoses (34 908 amniocenteses and 4197 chorionic villus samples) were made at the five largest clinical genetic laboratories in Sweden. Thirty-one cases of extra structurally abnormal chromosomes (ESACs) were found, giving a total prevalence of 0·8 per 1000. Twelve ESACs were inherited, 14 were de novo and in five the parental origin was unknown. This gives an estimated prevalence of 0·3–0·4 per 1000 for familial and 0·4–0·5 per 1000 for de novo ESACs. Retrospectively, the ESACs were characterized by fluorescence in situ hybridization (FISH). In nine cases, no material was available for this analysis. In 21 of the remaining 22 cases, the chromosomal origin could be identified by FISH. Seventeen of these (81 per cent) were derived from the acrocentric chromosomes, of which 13 originated from chromosome 15 (62 per cent). The most common ESAC was the inv dup(15) (57 per cent). Two cases were derived from chromosome 22, one from chromosome 14, and one from either chromosome 13 or chromosome 21. The four remaining cases consisted to two i(18p)s and two small ring chromosomes derived from chromosomes 4 and 19, respectively.     

Plasticity in echolocation signals of European pipistrelle bats in search flight: implications for habitat use and prey detection

We studied the echolocation and hunting behavior of three aerial insectivorous species of bats (Vespertilionidae: Pipistrellus) in the field in order to characterize the signals used by the bats and to determine how call structure varies in relation to habitat structure (uncluttered versus cluttered space). We documented free-flying, naturally foraging wild pipistrelles in various habitats using multiflash stereophotography combined with simultaneous sound recordings. Then we reconstructed the bat's flight position in three-dimensional space and correlated it with the corresponding echolocation sequences. In all three species of pipistrelles, signal structure varied substantially. In echolocation sequences of the search phase we found a consistent association of signal types with habitat types. In uncluttered habitats (obstacles more than 5 m from the bat) pipistrelles emitted almost exclusively narrowband signals with bandwidths less than 15 kHz. In cluttered habitats (obstacles less than 5 m from the bat) they switched to signals with bandwidths of more than 15 kHz. Wideband signals were also used when the bats were turning in cluttered and uncluttered spaces and for an instant after turning away from obstacles. Prey detection occured only when the outgoing signal did not overlap with the returning echo from potential prey. The bats also avoided overlap of echoes from potential prey and obstacles. Based on the results of this study, we propose an overlap-free window within which pipistrelles may detect potential prey and which allows predictions of minimum distances to prey and clutter-producing objects. Correspondence to: E.K.V. Kalko     

Interaction of limestone grains and acidic solutions from the oxidation of pyrite tailings

To characterise the coatings formed and to analyse element partitioning between the aqueous and solid phase, suspensions were prepared with four grain sizes of limestone and three different amounts of acidic solution from oxidized pyrite tailings. In all cases, red coatings with three different layers covered the grain surface, sealing off the acidic solution. The inner layer was composed mainly of basaluminite, the middle layer of schwertmannite, and the outer layer of gypsum and jarosite. Zn, Cd and Tl were co-precipitated by Fe and Al; As and Pb were co-precipitated almost completely by Fe; and Cu formed mainly Cu sulphates. All trace elements reached almost total precipitation at pH 6.3, but the precipitation of As and Pb tended to decrease as the pH rose. Consequently, liming should be calculated so that the soil pH does not exceed 6.3. This calculation should take into account that the armouring of the limestone grains can cause underestimations in the amount of liming material needed.     

Organochlorine compounds in common dolphins (Delphinus delphis) from the Atlantic and Mediterranean waters of Spain

Blubber of free-ranging common dolphins (Delphinus delphis) from the northwestern coast of Spain (Atlantic), sampled in 1984 and 1996, and of common dolphins entangled in fishing nets in the southwestern Mediterranean, sampled during 1992 1994, was analysed for organochlorine pollutants. In the Atlantic, concentration of all pollutants was significantly higher in males than in females. The overall tPCB/tDDT ratio in this area was 3.35, which indicates a predominance of industrial inputs over those associated with agriculture. Individuals sampled in 1996 showed significantly lower DDT concentrations but a higher ppDDE/tDDT ratio than those sampled in 1984, which reflects the aging of the environmental load. In the same period, tPCB concentration remained constant and, as a consequence, the tPCB/tDDT ratio more than doubled. In the Mediterranean, the reduced sample size of adult individuals precluded proper statistical investigation of sex-related variation. The overall tPCB/tDDT ratio was 1.12, suggesting a higher contribution of pollutants of agricultural origin. Individuals had significantly higher levels of all DDT forms and a higher ppDDE/tDDT ratio than their counterparts from the Atlantic, but similar PCB concentrations. However, the relative frequency of the different congeners in relation to the total PCB load was different in the two areas. This indicates that the two populations do not mix, at least in the short- or medium-term. Organochlorine levels in both areas are at the mid to low end of the range of concentrations detected in other common dolphin populations and in that of other Delphinidae species from the same region. Although the impact of the organochlorine concentrations on the common dolphin populations surveyed cannot be assessed, it is considered unlikely that they have played a significant role in the decline that the species has suffered in recent decades in the western Mediterranean.     

Kinetics of peat soil dissolved organic carbon release from bed sediment to water. Part 1. Laboratory simulation

Temporary water reservoirs built upon peat soil may exhibit water quality impairment from elevated dissolved organic carbon (DOC). Microbiological decay of the organic carbon in the bed with subsequent release produces "tea" colored water which may require treatment prior to use. This paper describes laboratory experiments designed to obtain data on the release process of DOC from soils containing 0.65%, 10% and 19% carbon. Parallel experiments with and without sodium azide treatment clearly distinguished the initial release of a porewater residual fraction and the microbial produced fraction. A one to two day quick-release DOC fraction, which ranges from 28% to 50%, first emerged from the bed, Step-1. This was followed by a constant rate of DOC production over four weeks, Step-2. The Step-2 average production rates were 3.4, 12, and 31 mg DOC/kg(dry)/day for the respective soils and increased as soil carbon content increased. The inorganic carbon (IC) behaved oppositely; its rate of production decreased with increasing soil carbon. A consistent and simple rate equation described the Step-2 DOC production process. This and other evidence obtained provided the basis for developing a mathematical model that couples both steps of the bed-to-water DOC release chemodynamics. The model is presented in a companion paper (Part-2).