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USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES
Cummings, K. T., R. Keys, K Bradham, S L. Harper, M MedinaVera, AND A. AbuShakra. USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES. Presented at The Southeastern Regional Meeting of the American Chemical Society, Research Triangle Park, NC, November 10-13, 2004.
The objective of this task is to develop state-of-the-science methods for evaluating toxic elements. These methods will include measuring bioavailable concentrations of toxic elements as well as enhanced traditional methods. Once established, the performance of these methods will be demonstrated on a small set of samples. Procedures will be documented such that they are readily transferable to EPA and non-EPA researchers.
Specific objectives of this task include:
1) Development of more sensitive and rapid quantitative procedures for evaluating exposure to toxic elements.
2) Assessment of the bioavailability of toxic elements in environmental media using bioavailability tools.
3) Application of this data to improve the scientific basis of site and source specific risk assessments.
4) Application of these methods to fill critical data gaps identified in the aggregate/cumulative exposure and risk research area of the Human Health Risk Assessment research plan.
Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. The use of pelletized seeds in plant studies would allow for a much greater diversity of seeds resources to be utilized. The following work compared the germination of pelleted, de-pelleted, and raw lettuce seeds to see if the pelleted seeds could be used in such studies. Pelleted and raw lettuce seeds were obtained from commercial sources. Pelleted seeds were de-pelleted in the lab by placing 100 seeds in a 50ml centrifuge tube, adding 30ml deionized water, and shaking gently for 3 min. The mix was filtered on qualitative filter paper in a Buchner funnel with vacuum for 3 min, and the filter paper was removed to air dry on the bench. Pelleted seeds contained approximately 10% seeds by weight, with the 90% pellet comprised of soluble and insoluble components. Pelleted, de-pelleted, and raw seeds were germinated in Petri dishes on two layers of germination blotter paper at 15oC with a 16h light/8h dark photoperiod (90 umol m-2 s-1 photosynthetic photon flux density (PPFD)). Total germination of the pelleted, de-pelleted, and raw seeds was identical (>90%) at 7 days. The de-pelleted and raw seeds had identical germination and growth time course plots. The pelleted seeds lagged behind in germination slightly up to 4 days, but were identical to the de-pelleted and raw seeds by 5 days. The work indicates that pelleted lettuce seeds could be used in plant toxicology or bioavailability studies provided such studies were longer than approximately 5-7 days.
This is an abstract of a proposed presentation and does not necessarily reflect the United States Environmental Protection Agency (EPA) policy. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
HUMAN EXPOSURE AND ATMOSPHERIC SCIENCES DIVISION
METHODS DEVELOPMENT & APPLICATION BRANCH