Uptake and biotransformation of pure commercial microcystin-LR versus microcystin-LR from a natural cyanobacterial bloom extract in the aquatic fungus Mucor hiemalis.

Objectives: To evaluate the remediation efficiency of Mucor hiemalis by comparing media elimination, uptake, and biotransformation of microcystin-LR with exposure to pure toxin versus a crude bloom extract.

Results: With exposure to the extract, the elimination rate of microcystin-LR from the media, which was 0.28 ng MC-LR l h, was significantly higher compared to that achieved with exposure to the pure toxin (0.

Daily expression pattern of protein-encoding genes and small noncoding RNAs in synechocystis sp. strain PCC 6803.

Many organisms harbor circadian clocks with periods close to 24 h. These cellular clocks allow organisms to anticipate the environmental cycles of day and night by synchronizing circadian rhythms with the rising and setting of the sun. These rhythms originate from the oscillator components of circadian clocks and control global gene expression and various cellular processes.

Diversity of KaiC-based timing systems in marine Cyanobacteria.

The coordination of biological activities into daily cycles provides an important advantage for the fitness of diverse organisms. Most eukaryotes possess an internal clock ticking with a periodicity of about one day to anticipate sunrise and sunset. The 24-hour period of the free-running rhythm is highly robust against many changes in the natural environment.

Multiple checkpoints for the expression of the chloroplast-encoded splicing factor MatK.

The chloroplast genome of land plants contains only a single gene for a splicing factor, Maturase K (MatK). To better understand the regulation of matK gene expression, we quantitatively investigated the expression of matK across tobacco (Nicotiana tabacum) development at the transcriptional, posttranscriptional, and protein levels. We observed striking discrepancies of MatK protein and matK messenger RNA levels in young tissue, suggestive of translational regulation or altered protein stability.

Revealing a two-loop transcriptional feedback mechanism in the cyanobacterial circadian clock.

Molecular genetic studies in the circadian model organism Synechococcus have revealed that the KaiC protein, the central component of the circadian clock in cyanobacteria, is involved in activation and repression of its own gene transcription. During 24 hours, KaiC hexamers run through different phospho-states during daytime. So far, it has remained unclear which phospho-state of KaiC promotes kaiBC expression and which opposes transcriptional activation.

A sequestration feedback determines dynamics and temperature entrainment of the KaiABC circadian clock.

The circadian rhythm of the cyanobacterium Synechococcus elongatus is controlled by three proteins, KaiA, KaiB, and KaiC. In a test tube, these proteins form complexes of various stoichiometry and the average phosphorylation level of KaiC exhibits robust circadian oscillations in the presence of ATP. Using mathematical modeling, we were able to reproduce quantitatively the experimentally observed phosphorylation dynamics of the KaiABC clockwork in vitro.