Correlation of foliar MT2b expression with Cd and Zn concentrations in hybrid aspen (Populus tremulaxtremuloides) grown in contaminated soil.

Metal uptake and its effect on foliar metallothionein 2b (MT2b) mRNA levels were studied in hybrid aspen (Populus tremulaxtremuloides) in field conditions. The trees were planted on a site contaminated with several metals, including cadmium (mean 5.1 mgkg(-1)), chromium (80 mgkg(-1)), copper (180 mgkg(-1)), nickel (81 mgkg(-1)), vanadium (240 mgkg(-1)) and zinc (520 mgkg(-1)).

Community structure of the bacteria associated with Nodularia sp. (Cyanobacteria) aggregates in the Baltic Sea.

The community structure of the bacteria associated with Nodularia spumigena (Mertens) cyanobacterial aggregates in the Baltic Sea was studied with temperature gradient gel electrophoresis (TGGE), using a 16S rRNA gene fragment as a target. Various developmental stages of the aggregates and free-floating cyanobacterial filaments were sampled to reveal possible changes in associated microbial community structure during development and senescence of the aggregates. The microbial community structures of all samples differed, and the communities of young and decaying aggregates were separated by cluster analysis of the TGGE fingerprint data.

Occurrence of nitrifiers and diversity of ammonia-oxidizing bacteria in developing drinking water biofilms.

We studied the population dynamics of nitrifying bacteria during the development of biofilms up to 233 or 280 days on polyvinylchloride pipes connected to two full-scale drinking water distribution networks supplying processed and chloraminated surface water. The numbers of nitrifiers in biofilms were enumerated at intervals of 10-64 days by the most probable number (MPN) method at waterworks and at several study sites in distribution network areas. The numbers of nitrifiers increased towards the distal sites.

Baltic Sea cyanobacterial bloom contains denitrification and nitrification genes, but has negligible denitrification activity.

Abstract A cyanobacterial bloom in the Gulf of Finland, Baltic Sea, was sampled throughout the development and senescence of aggregates in August 1999. While conditions inside the aggregates were favourable for denitrification (rich in nitrogen and carbon, with anoxic microzones), essentially none was detected by a sensitive isotope pairing method. Polymerase chain reaction-based methods, targeting functional genes encoding the key enzymes of denitrification and nitrification processes (nirS, nirK, amoA), revealed that the non-aggregated filaments harboured amoA gene fragments with high similarity to Nitrosospira amoA sequences, as well as both types of nitrite reductase genes, nirS and nirK.

Hereditary minisatellite mutations among the offspring of Estonian Chernobyl cleanup workers.

A single accidental event such as the fallout released from the Chernobyl reactor in 1986 can expose millions of people to non-natural environmental radiation. Ionizing radiation increases the frequency of germline mutations in experimental studies, but the genetic effects of radiation in humans remain largely undefined. To evaluate the hereditary effects of low radiation doses, we compared the minisatellite mutation rates of 155 children born to Estonian Chernobyl cleanup workers after the accident with those of their siblings born prior to it.