Maintenance of bivalve hemocytes for the purpose of delayed DNA strand break assessment using the comet assay.

The lack of appropriate methods for storing intact and viable cells for the purpose of delayed DNA strand break analysis has hitherto limited the application of the Comet assay to in vitro or in vivo laboratory studies and restricted ecologically more relevant field-collected samples to sites in proximity to suitable laboratory facilities. In the present article, osmotically corrected cell culture media Hanks Balanced Salt Solution (HBSS) and Leibovitz Media (L-15) were assessed for their suitability as temporary storage media of blue mussel (Mytilus edulis) hemocytes. It was found that hemocytes maintained in either HBSS or L-15 could be stored for at least 7 days at 4 degrees C without any significant deterioration in cell viability (Trypan blue) or increase in DNA strand breaks, expressed as % tail DNA. This approach allows the acquisition and examination of samples from organisms exposed in situ at previously unsuitable remote sites, thereby greatly increasing the potential ecological relevance of Comet assay-derived genotoxicity data.

Biodegradation of crude oil across a wide range of salinities by an extremely halotolerant bacterial consortium MPD-M, immobilized onto polypropylene fibers.

The bacterial consortium MPD-M, isolated from sediment associated with Colombian mangrove roots, was effective in the treatment of hydrocarbons in water with salinities varying from 0 to 180 g L(-1). Where the salinity of the culture medium surpassed 20 g L(-1), its effectiveness increased when the cells were immobilized on polypropylene fibers. Over the range of salinity evaluated, the immobilized cells significantly enhanced the biodegradation rate of crude oil compared with free-living cells, especially with increasing salinity in the culture medium. Contrary to that observed in free cell systems, the bacterial consortium MPD-M was highly stable in immobilized systems and it was not greatly affected by increments in salinity. Biodegradation was evident even at the highest salinity evaluated (180 g L(-1)), where biodegradation was between 4 and 7 times higher with immobilized cells compared to free cells. The biodegradation of pristane (PR) and phytane (PH) and of the aromatic fraction was also increased using cells immobilized on polypropylene fibers.