Hormesis - Stimulation Of Colony Growth In Campanularia-Flexuosa (Hydrozoa) By Copper Cadmium And Other Toxicants

It is shown experimentally that subinhibitory concentrations of a number of toxic, or other agents that are typically inhibitory (copper, cadmium, tributyl tin fluoride, reduced salinity), may stimulate the growth of colonies of the hydroid Campanularia flexuosa, exhibiting a phenomenon known as hormesis. It is suggested that the stimulation of growth is not due to the specific properties of the different toxicants, but to an adaptive response of the hydroid to the inhibitory effect that they have in common. Growth is regulated by a control mechanism and it is proposed that the increased growth is a consequence of overcorrections to low levels of an inhibitory challenge. Examination of the toxicological literature shows that hormesis is a more common occurrence that is generally supposed, and it is suggested that the explanation given here might apply in other cases of hormesis.

Simulating The Impact Of Technological-Change On Dissolved Cadmium Distribution In The Severn Estuary

An estuarine model is described which computes the dispersive and advective properties of the Severn Estuary. It was calibrated and validated using 50 measured salinity distributions and then used to predict the magnitude and sitings of the major inputs of dissolved cadmium levels throughout the estuary. The results provided an impetus for implementing tighter controls on effluents and for improving estimates of cadmium discharges from industrial sources. The model has also been used to investigate the sensitivity of the estuarine system to changes in dispersion; by considering large reductions in the dispersion coefficients it is hoped that the results might be indicative of the environmental consequences following the construction of a tidal power generating scheme.

Isotopic Abundances Of Lead In Estuarine Sediments Swansea Bay Bristol Channel

A historical record for the deposition of lead in Swansea Bay, Bristol Channel, U.K. has been determined together with isotopic compositions. Analysis of the isotopic composition of lead in cores, dated by 210Pb-210Po chronology, illustrated a post ~ 1850 influx of lead originating from technically produced materials. Since ~ 1850 there has been a × 3 increase of lead in sediments of which only 25–30% can be accounted for from technical sources; the remainder is presumed to be derived from working of the South Wales Coal Measures.

The origin and evolution of synaptic proteins - choanoflagellates lead the way.

The origin of neurons was a key event in evolution, allowing metazoans to evolve rapid behavioral responses to environmental cues. Reconstructing the origin of synaptic proteins promises to reveal their ancestral functions and might shed light on the evolution of the first neuron-like cells in metazoans. By analyzing the genomes of diverse metazoans and their closest relatives, the evolutionary history of diverse presynaptic and postsynaptic proteins has been reconstructed. These analyses revealed that choanoflagellates, the closest relatives of metazoans, possess diverse synaptic protein homologs. Recent studies have now begun to investigate their ancestral functions. A primordial neurosecretory apparatus in choanoflagellates was identified and it was found that the mechanism, by which presynaptic proteins required for secretion of neurotransmitters interact, is conserved in choanoflagellates and metazoans. Moreover, studies on the postsynaptic protein homolog Homer revealed unexpected localization patterns in choanoflagellates and new binding partners, both which are conserved in metazoans. These findings demonstrate that the study of choanoflagellates can uncover ancient and previously undescribed functions of synaptic proteins.