An experiment in >1000 river and riparian sites found spatial patterns and controls of carbon processing at the global scale.

This study showed first results on the geographical distribution of mixotrophic ciliates of the genus Stentor in the Chilean North Patagonian Lake District. Thirteen deep North Patagonian lakes were sampled during 2004 and 2005, and important ecological parameters as nutrients, light climate, chlorophyll a and all plankton groups were analysed. The data were evaluated using correlation, cluster and discriminant function analyses.In four of 13 lakes, Stentor was an important constituent of the plankton community and contributed significantly to the total zooplankton biomass. It coinhabited lakes with calanoid copepods (Boeckella, Tumeodiaptomus) and small cladocerans (Eubosmina, Ceriodaphnia). Stentor was negatively correlated with cyclopoid copepods and large cladocerans. Cyclopoid copepods were a very good predictor to discriminate between lakes with and without Stentor. It is suggested that cyclopoid copepods have top-down impact on Stentor.

To determine whether the CLCA gene family of calcium-activated chloride channels is a modulator of the basic defect of cystic fibrosis (CF), an association study was performed with polymorphic microsatellite markers covering a 40-Mbp region spanning the CLCA gene locus on human chromosome 1p in CF patients displaying CF transmembrane conductance regulator (CFTR)-independent residual chloride conductance in gastrointestinal epithelia. Statistically significant association of the electrophysiological phenotype with the allele distribution of markers 5' of and within the CLCA locus was observed. Transmission disequilibrium and the significance of the association decreased within the locus from hCLCA2 towards hCLCA4. Expression of hCLCA1 and hCLCA4 in human rectal mucosa was proven by microarray analysis. The CLCA gene region was identified to encode mediators of DIDS-sensitive anion conductance in the human gastrointestinal tract that modulate the CF basic defect.

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1. Large mixotrophic ciliates (Stentor araucanus, S. amethystinus and Ophrydium naumanni) were a characteristic component of a temperate, oligotrophic lake in North Patagonia. During a 1‐year study, the abundance, biomass and primary production of these large Chlorella‐bearing ciliates were compared with those of the total plankton community. 2. Mixotrophic ciliates peaked in spring and from late summer to autumn, accounting for 1.6–43% (annual average: 16.3%) and 67–99% (annual average: 92%) of total ciliate abundance and biomass, respectively. Their contribution to total zooplankton biomass, including flagellates, rotifers, ciliates and crustaceans, was 14–76%, or 47% as an annual average. Endosymbiotic algae accounted for up to 25% of total autotrophic biomass (annual mean: 3.9%). 3. Maximum cell‐specific photosynthetic rates of S. araucanus and S. amethystinus at light saturation varied between 80 and 4400 pg C ciliate–1 h–1 with high values during autumn and winter, and low values during summer. The depth‐integrated rates of photosynthesis (0–40 m) of algal endosymbionts contributed 1–25% to total photosynthesis (annual mean: 6.5%). 4. A comparison of calculated ingestion rates with photosynthetic rates of Stentor indicates that photosynthate produced by endosymbionts generally exceeded heterotrophic food supply of Stentor during autumn and winter, but was much lower during summer, when food supply was high. 5. The mixotrophic ciliates represent an important ‘link’ between nanoplankton and higher trophic levels within the plankton community because of their high heterotrophic biomass and considerable contribution to total photosynthesis.