Genotypes of Nicotiana attenuata collected from Utah and Arizona were transformed with 17 different vectors (14 unpublished vectors based on 3 new backbone vectors) using an Agrobacterium-mediated procedure to functionally analyze genes important for plant-insect interactions. None of the 51 T1-T3 transgenic Utah lines analyzed by the flow cytometry were tetraploid, as opposed to 18 of 33 transgenic Arizona lines (55%). Analysis of T0 regenerants transformed with the same vector carrying an inverted repeat (IR) N. attenuata pro-systemin construct confirmed the genotype dependency of tetraploidization: none of the 23 transgenic Utah lines were tetraploid but 31 (72%) of 43 transgenic Arizonas were tetraploid. We tested the hypothesis that the differences in polysomaty of the explant tissues accounted for genotype dependency of tetraploid formation by measuring polysomaty levels in different seedling tissues. Hypocotyls, cotyledons, and roots of Utah and Arizona genotypes contained similar percentages of 4C nuclei (61 and 60; 7 and 5; and 58 and 61%, respectively). Since we used hypocotyls as explant sources and the nonoccurrence of tetraploid Utah transformants does not correspond to the high percentage of 4C nuclei in Utah hypocotyls, we can rule out a direct relationship between tetraploid formation and polysomaty level. We hypothesize that the difference between the Utah and Arizona genotypes results from the failure of polyploid Utah callus to regenerate into fully competent plants. We propose that future work on post-transformation polyploidy concentrate on the processes that occur during callus formation and plant regeneration from callus.

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An updated, optimized method has been developed to minimize the chemical biases and inefficiencies between two EPA SW-846 alternative leach methods, microwaveassisted Method 3051 and open vessel Method 3050B, for the determination of metals in solid samples. The microwave method is more easily transferred and provides more reproducible leach results, mainly from more precise control of the temperature during the extraction process. Previously, reagent limitations originally placed on Method 3051 did not allow these alternative methods to yield similar results for some analytes. This work describes the development and validation of EPA Method 3051A, which includes an option to add HCl to improve the chemistry of the microwave method, making it comparable to open vessel Method 3050B. Including HCl provides complexation and stabilization of some analytes by Clspecies, leading to improved recoveries. Optimizing the acid combination involved adding either 1, 3, or 5 mL of HCl to 9 mL of HNO 3 and performing a series of leaches on standard reference materials (SRMs). Optimum recoveries are achieved for "problem" analytes, such as Ag and Sb, by adding 3 mL of HCl. Recovery of other metals, such as Cu and Ni, are unaffected. Method validation was provided by leaching and analysis of SRMs.

In order to characterize the mercury hazard in soil, a sequential extraction scheme has been developed to classify mercury species based on their environmental mobility and/or toxicity for either routine lab analysis or on-site screening purposes. The alkyl mercury species and soluble inorganic species that contribute to the major portion of potential mercury toxicity in the soil are extracted by an acidic ethanol solution (2% HCl+10% ethanol solution) from soil matrices as "mobile and toxic" species. A High-Performance Liquid Chromatography (HPLC) system coupled with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) detection has been developed to further resolve the species information into soluble inorganic species (Hg(2+)), methylmercury(II) (MeHg(+)) and ethylmercury(II) (EtHg(+)) species. Alternatively, these species can be separated into "soluble inorganic mercury" and "alkyl mercury" sub-categories by Solid-Phase Extraction (SPE). A custom Sulfydryl Cotton Fiber (SCF) material is used as the solid phase medium. Optimization of the SCF SPE technique is discussed. Combined with a direct mercury analyzer (DMA-80), the SCF SPE technique is a promising candidate for on-site screening purposes. Following the ethanol extraction, the inorganic mercury species remaining in soil are further divided into "semi-mobile" and "non-mobile" sub-categories by sequential acid extractions. The "semi-mobile" mercury species include mainly elemental mercury (Hg) and mercury-metal amalgams. The non-mobile mercury species mainly include mercuric sulfide (HgS) and mercurous chloride (Hg(2)Cl(2)).

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