Flow cytometric sorting of loricate choanoflagellates from the oligotrophic ocean.

It is challenging to study protists with extensive, loosely-associated extracellular structures because of the problems with keeping specimens intact. Here we have tested the suitability of high-speed flow cytometric sorting as a tool for studying such protists using oceanic loricate choanoflagellates as a model. We chose choanoflagellates because their lorica-to-cell volume ratio is > 10 and the voluminous loricae, i.

Notable predominant morphology of the smallest most abundant protozoa of the open ocean revealed by electron microscopy.

In the microbe-driven ecosystems of the open ocean, the small heterotrophic flagellates (sHF) are the chief microbial predators and recyclers of essential nutrients to phototrophic microbes. Even with intensive molecular phylogenetic studies of the sHF, the origins of their feeding success remain obscure because of limited understanding of their morphological adaptations to feeding. Here, we examined the sHF morphologies in the largest, most oligotrophic South Pacific and Atlantic (sub)tropical gyres and adjacent mesotrophic waters.

"Pomacytosis"-Semi-extracellular phagocytosis of cyanobacteria by the smallest marine algae.

The smallest algae, less than 3 μm in diameter, are the most abundant eukaryotes of the World Ocean. Their feeding on planktonic bacteria of similar size is globally important but physically enigmatic. Tiny algal cells tightly packed with the voluminous chloroplasts, nucleus, and mitochondria appear to have insufficient organelle-free space for prey internalization.

Influence of copper oxide nanoparticle shape on bioaccumulation, cellular internalization and effects in the estuarine sediment-dwelling polychaete, Nereis diversicolor.

CuO nanoparticles (NPs) released into the aquatic environment will likely accumulate in the sediment. Here we synthesized and characterized CuO NPs with different shapes and thus sizes: spheres, rods and spindles. Nereis diversicolor were exposed for 10 days to control sediment or sediment spiked with CuO NPs or aqueous Cu (Cu-Aq, CuCl2) at 7, 70 and 140 μg Cu g(-1) dw sediment.

In vivo retention of ingested Au NPs by Daphnia magna: no evidence for trans-epithelial alimentary uptake.

In vivo studies with Daphnia magna remain inconclusive as to whether engineered nanoparticles (NPs) are internalized into tissues after ingestion. Here we used a three-pronged approach to study the in vivo retention and efflux kinetics of 20 nm citrate stabilized Au NPs ingested by this key aquatic species. Daphnids were exposed to suspended particles (600 μg L(-1)) for 5 h after which they were depurated for 24 h in clean water containing algae.