Euglenoid pellicle morphogenesis and evolution in light of comparative ultrastructure and trypanosomatid biology: Semi-conservative microtubule/strip duplication, strip shaping and transformation.

Uniquely in eukaryotes, euglenoid pellicles comprise longitudinal proteinaceous, epiplasmic strips underlain by microtubules. Contradictory interpretations of pellicle microtubule duplication and segregation assumed opposite microtubule polarity from kinetoplastid Euglenozoa and conservative microtubule segregation. Distigma shows new pellicle microtubules nucleating posteriorly as in trypanosomatids, unifying euglenoid and kinetoplastid pellicle morphogenesis, but strip-growth is unpolarised. Epiplasmic insertion and cutting make new strip junctions between alternating wide and narrow daughter strips that grow intussusceptively. Nanotubules, overlooked epiplasm-associated components, define strip edges. At strip heel/toe junctions all euglenoids have a morphogenetic centre microtubule mt2/3 pair. Arguably, proteolysis, epiplasmic growth, and toe-nanotubule-associated epiplasmic scission initiate daughter strips, separating old mts2/3; new mt2/3/bridge-B assembly, sub-heel scission, nanotubule-bridge-A assembly complete duplication. Only mt2/3 pair fully enters the canal, one master microtubule also the reservoir, other pellicle microtubules terminating near canal rims. A related cytokinesis model involving ciliary attachment zone duplication explains near-universally even spirocute strip number. I consider Serpenomonas and Entosiphon alternating heteromorphic strips developmental stages of 'strip transformation'; explain intergroup diversity of strip morphology and dorsoventral strip differentiation causally by specific pellicle-complex components; propose centrin-based mechanisms for strip shaping and euglenoid movement; unify pellicle cytokinetic microtubule segregation across Euglenozoa; and discuss origin and diversification of pellicle complexes.

Toxic effects of oil sand naphthenic acids on the biomass accumulation of 21 potential phytoplankton remediation candidates.

The oil sands of northern Alberta, Canada contain an estimated 170 billion barrels of crude oil. Extraction processes produce large amounts of liquid tailings known as oil sand process affected water (OSPW) that are toxic to aquatic organisms. Naphthenic acids (NAs), and their sodium salts, represent a significant contributor to the toxicity of these waters. Due to the recalcitrant nature of these compounds, an effective mode of remediation has yet to be established. This study investigates the suitability of the use of phytoplankton for remediation efforts based on two criteria: the ability of phytoplankton strains to withstand the toxic effects of NAs, and their rate of biomass accumulation. A total of 21 phytoplankton strains were isolated from waters containing NAs, cultured, and maintained under unialgal conditions. These strains were then exposed to NAs in concentrations ranging from 0mg L(-1) to 1000mg L(-1) over a 14 day period. Inhibition of growth was observed at 30mg L(-1) NA (one strain), 100mg L(-1) NA (one strain), 300mg L(-1) NA (six strains), and 1000mg L(-1) NA (six strains). Five strains failed to show any growth inhibition at any test concentration and two strains could not be analysed due to poor growth during the test period. Strains were then ranked based on their suitability for use in remediation efforts.