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Modeling inactivation of indicator microorganisms is a necessary component of microbial water quality forecast and management recommendations. The linear semi‐logarithmic (LSL) model is commonly used to simulate the dependencies of bacterial concentrations in waters on time. There were indications that assumption of the semi‐logarithmic linearity may not be accurate enough in waters. The objective of this work was to compare performance of the LSL and the two‐parametric Weibull inactivation models with data on survival of indicator organism Escherichia coliin various types of water from a representative database of 167 laboratory experiments. The Weibull model was preferred in >99% of all cases when the root mean squared errors and Nash–Sutcliffe statistics were compared. Comparison of corrected Akaike statistic values gave the preference to the Weibull model in only 35% of cases. This was caused by (i) a small number of experimental points on some inactivation curves, (ii) closeness of the shape parameter of the Weibull equation to one, and (iii) piecewise log–linear inactivation dynamic that could be well described by neither of the two models compared. Based on the Akaike test, the Weibull model was favored in agricultural, lake, and pristine waters, whereas the LSL model was preferred for groundwater, wastewater, rivers, and marine waters. The decimal reduction time parameter of both the LSL and Weibull models exhibited an Arrhenius‐type dependence on temperature. Overall, the existing E. coliinactivation data indicate that the application of the Weibull model can improve the predictive capabilities of microbial water quality modeling.

Multicolored imaging: A new class of molecular imaging agent has been developed based on low‐molecular‐weight organically soluble bismuth to detect and quantify intraluminal fibrin presented by ruptured plaque in the context of computed tomography angiograms without calcium interference.

The complex permittivity for Pt, Pd, Ni, and Ti-silicide films as well as heavily doped p- and n-type silicon were determined by ellipsometry over the energy range 0.031 eV to 4.0 eV. Fits to the Drude model gave bulk plasma and relaxation frequencies. Rutherford backscattering spectroscopy, X-ray diffraction, scanning electron microscopy, secondary ion mass spectrometry, and four-point probe measurements complemented the optical characterization. Calculations from measured permittivities of waveguide loss and mode confinement suggest that the considered materials are better suited for long-wavelength surface-plasmon-polariton waveguide applications than metal films.

Nanomedicine approaches to atherosclerotic disease will have significant impact on the practice and outcomes of cardiovascular medicine. Iron oxide nanoparticles have been extensively used for nontargeted and targeted imaging applications based upon highly sensitive T2* imaging properties, which typically result in negative contrast effects that can only be imaged 24 or more hours after systemic administration due to persistent blood pool interference. Although recent advances involving MR pulse sequences have converted these dark contrast voxels into bright ones, the marked delays in imaging from persistent magnetic background interference and prominent dipole blooming effects of the magnetic susceptibility remain barriers to overcome. We report a T1-weighted (T1w) theranostic colloidal iron oxide nanoparticle platform, CION, which is achieved by entrapping oleate-coated magnetite particles within a cross-linked phospholipid nanoemulsion. Contrary to expectations, this formulation decreased T2 effects thus allowing positive T1w contrast detection down to low nanomolar concentrations. CION, a vascular constrained nanoplatform administered in vivopermitted T1w molecular imaging 1 h after treatment without blood pool interference, although some T2 shortening effects on blood, induced by the superparamagnetic particles, persisted. Moreover, CION was shown to encapsulate antiangiogenic drugs, like fumagillin, and retained them under prolonged dissolution, suggesting significant theranostic functionality. Overall, CION is a platform technology, developed with generally recognized as safe components, that overcomes the temporal and spatial imaging challenges associated with current iron oxide nanoparticle T2 imaging agents and which has theranostic potential in vascular diseases for detecting unstable ruptured plaque or treating atherosclerotic angiogenesis.

Information on the concurrent release and interactions between manure-borne phosphorus (P) and enteric bacteria to runoff from a live or dead grass sod is limited. A study of simulated runoff and an enzyme-based fractionation of runoff P forms from dairy manure applied on grass-covered soil in runoff boxes was conducted to compare the detachment and potential edge-of-field movement of manure P, Escherichia coli, and enterococci in runoff. Concentrations and mass loads of bioactive P forms and bacteria in runoff were log-normally distributed over time during all simulations. Although P and enteric bacteria were simultaneously released to runoff, high correlations were found predominantly between water turbidity, concentrations of bacteria, and phosphohydrolase-labile P, a fraction associated with particulate manure. Delayed bacteria and particulate P concentrations and mass loads indicated live leaf and bacterial surface interactions that impeded their release to runoff. Resultant deviations in linearity between manure water-extractable P and bacteria distributions and the significant correlation between bacteria and the phosphohydrolase-labile P fraction suggested that manure-borne E. coliwere released in association with manure particulates that contained organic P. The state of the grass cover determined the asymmetry of bacteria and bioactive P distributions. Given the micrometer size range of suspended particles, losses of colloidal particulate P and colloid-associated bacteria may extend well beyond the immediate vicinity of the deposited manure.

Background: Atherosclerosis is a chronic, inflammatory disease in which ruptured plaques can lead to serious thrombotic events, including myocardial infarction or stroke. Often these cardiovascular events occur with no previous recognition of symptoms and only moderate stenosis. New diagnostic techniques are needed for earlier diagnosis and staging of atherosclerotic disease, so appropriate treatments, interventional procedures, or lifestyle changes can begin. Recent developments in nanotechnology could advance clinical imaging of molecular biomarkers, particularly for cardiovascular diagnosis. Objective: In this review, selected nanotechnologies under development for early detection of atherosclerotic disease and identification of vulnerable plaques are presented. Method: The scope of this review encompasses molecular imaging of atherosclerosis using nanoparticle contrast agents. Nanoparticle approaches are grouped by their corresponding diagnostic imaging modality. Results/conclusion: Diagnostic imaging techniques employing nanoparticle contrast agents targeted to molecular signatures of atherosclerotic disease offer hope for improved non-invasive detection.

Attachment of bacteria to soil is an important component of bacterial fate and transport. Escherichia coliare commonly used as indicators of fecal contamination in the environment. Despite the fact that E. coliare derived exclusively from feces or manure, effect of the presence of manure colloids on bacteria attachment to agricultural soils was never directly studied. The objective of this work was to evaluate the magnitude of the effect of manure on E. coliattachment to soil. Escherichia coliattachment to soil was studied in batch experiments with samples of loam and sandy clay loam topsoil that were taken in Pennsylvania and Maryland. Escherichia colicells were added to the water–manure suspensions containing 0, 20, and 40 g L−1of filtered liquid bovine manure, which subsequently were equilibrated with air‐dry sieved soil in different soil to suspension ratios. The Langmuir isotherm equation was fitted to data. Manure dramatically affected E. coliattachment to soil. Attachment isotherms were closer to linear without manure and were strongly nonlinear in the presence of manure. The maximum E. coliattachment occurred in the absence of manure. Increasing manure content generally resulted in decreased attachment.

Molecular vascular imaging represents a novel tool that promises to change the current medical paradigm of ‘see and treat to a ‘detect and prevent strategy. Nanoparticle agents, such as superparamagnetic nanoparticles and perfluorocarbon nanoparticle emulsions, have been developed for noninvasive imaging, particularly for magnetic resonance imaging. Designed to target specific epitopes in tissues, these agents are beginning to enter clinical trials for cardiovascular applications. The delivery of local therapy with these nanoparticles, using mechanisms such as contact-facilitated drug delivery, is in the advanced stages of preclinical research. Ultimately, combined diagnostic and therapeutic nanoparticle formulations may allow patients to be characterized noninvasively and segmented to receive custom-tailored therapy. This review focuses on recent developments of nanoparticle technologies with an emphasis on cardiovascular applications of magnetic resonance imaging.

Most experiments on 1RS translocations in wheat (Triticum aestivumL.) cannot separate the effects of introgressions of rye (Secale cerealeL.) chromosome arm from the absence of corresponding wheat chromosome arms. The objective of this research was to determine the contribution of individual wheat and rye group 1 chromosome arms. Five group 1 ditelosomics, six substitutions, and 16 translocations of 1R in wheat were compared with appropriate controls. All ditelosomics were significantly different from controls for 100‐kernel weight (100‐KW), flour protein content (FP), Mixograph peak time (MT) and tolerance (MTO), and sodium dodecyl sulfate sedimentation (SDSS) volume. Among the long arms, 1DL was the most important for end‐use quality and 1AL the least important, ranking even below the 1RL tested. The contribution of all short arms was low. Substitutions of 1R negatively impacted agronomic performance with the long arm being entirely responsible for this effect. Among translocation lines, those with 1RS.1BL had the highest yield and those with 1RS.1DL the lowest. Negative impact of all translocations of 1RS on the end‐use quality was far greater than the absence of the corresponding 1S arms of wheat. Translocation 1RS.1AL was the least detrimental to quality and 1RS.1DL the most detrimental. Both the source of the rye chromatin and its position in the wheat genome affected agronomic performance and quality. These results suggest that it may be possible to create new translocations of 1RS in wheat with improved performance. Translocation of 1RS to 1AL is preferred from a quality point of view; that to 1BL appears more beneficial for agronomic performance.

Few experiments have studied how seeding rates affect agronomic performance and end‐use quality of modern wheat (Triticum aestivumL.) genotypes in the Great Plains. Higher grain yield and better quality grain production requires the use of appropriate seeding rates. During the 1997 and 1998 crop seasons, 20 winter wheat genotypes and experimental lines were evaluated at two locations (four environments) to assess seeding rate and genotype effects on agronomic performance and end‐use quality of wheat. Significant differences among environments, seeding rates, and genotypes, and some of their interactions were identified. Lower seeding rates decreased plant population (by 62.3%), grain yield (by 0.8 Mg ha−1), kernel weight (by 1.3 mg kernel−1), flour yield (by 0.8 g/100 g grain), mixing time (by 0.7 min), caused later flowering (by 2 d), and increased flour protein content (by 15 mg g−1) and mixing tolerance (1 unit). Environment × genotype interactions were significant for all the traits except plant population and mixing tolerance. On the basis of the four environments, the seeding rate × genotype interactions were nonsignificant for all traits except plant height. These results provide evidence that agronomic performance and end‐use quality traits are greatly influenced by the environmental conditions and less so by seeding rates. Seeding rate affected plant population, days to flowering, plant height, grain yield, kernel weight, flour yield, flour protein, and mixing time and tolerance of wheat; therefore, seeding rate should be considered as a factor in obtaining higher grain yields with good end‐use quality.

Chromosomal translocations between wheat (Triticum aestivumL.) and rye (Secule cerealeL.) have been associated with an increase in grain yield and a decrease in end‐use quality in hard red winter wheat. Although demonstrated with a 1BL.lRS translocation, less information is available regarding the effect of 1AL.lRS translocations. The objective of this study was to determine the effect of a 1AL.lRS translocation in hard red winter wheat on end‐use quality traits and their stability across environments. From the heterogeneous 1AL.lRS wheat cultivar Nekota, 18 homogeneous 1A lines (non‐lRS), 16 1AL.lRS lines, four composites (lA, lAL.lRS, lAL.lRS+ lA, and Nekota), and six cultivars were tested in eight Nebraska environments. The 1AL.lRS translocation increased flour protein content (5.5 mg g−1), but decreased flour yield (14.2g kg−1), Mixograph mixing time (from 23−2.7 min), and Mixogaph mixing tolerance rating (from 3.5−3.1). Despite higher flour protein content in 1AL.lRS lines, the 1AL.lRS translocation did not enhance other end‐use quality traits. On the basis of linear regression, the 1A and 1AL.lRS lines had similar stability values for flour yield and flour protein content. The 1A lines showed higher flour yield in all environments, while the 1AL.lRS lines had higher flour protein content in all environments. For Mixograph mixing time and mixing tolerance, the 1A lines were more responsive to the environment, while the 1AL.lRS lines had exceptional stability over all environments. The end‐use quality of Nekota can be explained by a mixture of 1A lines with acceptable to good quality and 1AL.lRS lines with poor to acceptable quality.

The presence of the short arm of rye (Secule cerealeL.) chromosome one (1RS) has been associated with an increase in grain yield in hard red winter wheat (Triticum aestivumL.). This positive effect has been demonstrated when the 1RS arm is present in the 1BL.lRS translocation. However, little information is available regarding the 1AL.lRS translocation. Our objective was to determine the effect of the 1AL.lRS translocation on yield and yield components and their stability across environments. Eighteen homogeneous 1A lines (non‐1RS) and 16 1AL.lRS lines were randomly derived from the heterogeneous cultivar Nekota. These 34 lines, four composites (lA, lAL.lRS, 1AL.lRS + lA, and Nekota), along with six check cultivars were grown in eight Nebraska environments. The 1AL.lRS translocation in the Nekota background increased kernel weight (3.3%) and grain volume weight (0.4%); had no effect on grain yield, kernels per spike, and anthesis date; and decreased plant height (1.2%) and number of spikes per square meter (2.9%). The 1A lines and 1AL.lRS lines were equally stable for grain yield, kernels per spike, spikes per square meter, and plant height. For kernel weight, the 1A lines were more responsive and tended to have heavier kernels under favorable environments, while the 1AL.lRS lines had heavier kernels under lower yielding environments. For grain volume weight, the 1A lines were more responsive than the 1AL.lRS lines, which had heavier grain volume weight under lower yielding environments. Hence, the 1AL.lRS translocation in Nekota was not beneficial for either agronomic performance or stability.

Typical commercial bakeries in the United States are highly mechanized, mass-production facilities. U.S. hard wheat breeding programs use small-scale physical dough testing and pup loaf bake procedures to identify and select improved quality genotypes. The accuracy of such approaches in the prediction of commercial-scale quality performance is poorly understood. Samples from six hard red winter wheat cultivars grown in 11 locations over three harvest years were used to correlate grain hardness, small-scale test bakes, mixograph variables, and various measures of flour protein composition with quality assessments from commercial test laboratories. Samples were milled on both pilot- and small-scale mills. Protein content and 100-g pup loaf volume were more often significantly correlated with commercial test bake variables than all other small-scale variables. Stepwise multiple regression models explained, on average, ˜40% of the variation in commercial test bake procedures. Mixograph properties, pup loaf volumes and absorption, and flour protein content were the most frequent variables identified in model development. Pup loaf bake results on pilot- and small-scale milled flours were highly correlated. Differences in milling technology do not appear to be a significant source of error in relating small-scale test bakes to commercial quality.

The three body correlation spectra in the collision induced light scattering by gaseous Ar, CH4, CF4 and SF6 at 295 K are reported. The zeroth and second frequency moments are compared with calculations based on a pairwise additive triplet cluster polarizability. It is found that the experimental results may be accounted for with the use of the first order dipole-induced dipole model for the polarizability. The spectra may be used to distinguish between the suitability of various intermolecular potentials; modern potentials give excellent results for Ar and CH4 and a Lennard-Jones 28-7 potential best describes the CF4 and SF6 spectra.

Winter wheat (Triticum aestivumL.) is grown under both conventional‐till and conservation‐till systems in the Northern Great Plains. A benefit of sowing winter wheat into standing stubble is the protection the crop receives from trapped snow and the resultant reduction in winter kill. A 5‐yr study was conducted at four locations in North Dakota to measure cultivar‐by‐tillage interactions for quality parameters of wheat and to determine whether testing under both conventional‐till and no‐till systems was advantageous. Fourteen hard red winter wheat cultivars were planted during 1984‐1985 through 1988‐1989 in a Max loam (fine‐loamy, mixed, Typic Haploborolls) at both Williston and Minot, in a Svea loam (fine‐loamy, mixed, Pachic Udic Haploborolls) at Langdon, and in a Bearden silty clay (fine‐silty, frigid, Aeric Calciaquolls) or Gardena silty loam (coarse‐silty, mixed, Pachic Udic Haploborolls) at Fargo. Significant cultivar‐by‐tillage interactions (P< 0.05 or P< 0.01) were obtained for volume weight, protein content, and flour yield when the analysis was restricted to environments in which wheat winter killed. A change in rank order of cultivars was detected only for volume weight. For the other quality parameters measured, evaluation of winter wheats grown in conventional‐till and no‐till plots resulted in similar relative performance of cultivars.

The objective of this study was to develop a method that could be applied to investigations of soil/environmental factors influencing the spatial and temporal variability of carbofuran hydrolysis in field soils. Two factors were considered: (i) soil handling and pesticide application, and (ii) the method of data summarization. Three soil handling/pesticide treatments were evaluated: (i) sieved soil/sprayed pesticide application, (ii) injected pesticide application/sieved soil, and (iii) injected pesticide application/intact core incubation. This last method was developed to mimic field conditions where high localized concentrations of carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate) occur as a result of banded application of granular carbofuran at planting time. For all three treatments sigmoidal 14CO2production kinetics were observed. Several mathematical models for describing sigmoidal product appearance data were evaluated and a general saturation model was found to yield the best fit. Using parameter estimates obtained from this model in statistical tests, we found that the intact core soil treatment yielded significantly longer half lives for carbofuran degradation. Additional experimental evidence suggests that soil structure of the intact cores retarded diffusion of the 14CO2produced from carbofuran degradation and influenced the kinetic pattern observed.

Three experiments of 5 wk duration were conducted to evaluate the effect of reduced nocturnal temperatures (RNT) on weaned pig performance. Treatments were 1) a control regimen (CR) of 30 C constant air temperature lowered 2 C/wk and 2) a regimen where the temperature from 1900 to 0700 h was lowered to 25 C for three nights followed by 20 C for four nights during the first week and then lowered 1 C/wk thereafter (RNT). Weaned pigs averaging 23 ± 2 d of age at the start of the experiments gained faster (P<.0J) in the RNT treatment vs the CR treatment in Exp. 1, 2 and 3, respectively (.32 Vs .28; .39 vs .37; .35 vs .34 kg/d). The improvement in gain was accompanied by an increase (P<.005) in feed intake for the same period (.48 vs .44; .61 vs .55; .58 vs .54 kg/d). There was no difference in feed conversion. Weaned pigs that were 1.9 to 2.3 kg lighter initially gained slower (P<.0005) compared with their heavier contemporaries (.27 vs .33; .33 vs .43 and .31 vs .33 kg/d) in Exp. 1, 2 and 3, respectively. This reduced gain was accompanied by a reduced (P<.0005) feed intake (.40 vs .51; .50 vs .66; .50 vs .62 kg/d). There was no interaction of initial weight and temperature regimen.

A soil core method is described for monitoring rates and extent of N-mineralization and denitrification from intact leguminous cover crops (e.g., hairy vetch) as a function of soil water content. The method also allows for estimates of N-fixation in order to perform N-mass balances. Field conditions were simulated by growing cover crops in soil cores from seed to biomass levels comparable to the field, followed by harvest/kill. Soil cores were wetted periodically using a rain simulator. After simulated rain events, samples of leachate were obtained and soil water content adjusted by application of a vacuum (15 kPa) to the bottom of cores. The use of a PVC/silica filter (bubble point = 30 kPa) allowed for cores to be drained to field capacity without pulling ambient air through the soil. N-fixation (before harvest/kill) and N-mineralization (after harvest/kill) were determined by comparing NO − [over] 3 leached from vetch with fallow cores. Denitrification was determined by periodically sealing cores, injecting and recirculating acetylene throughout cores, and quantifying N2O production after 48 h. Preliminary experiments with hairy vetch (Vicia villosa) indicate that plants are reasonably efficient at taking up soil NO − [over] 3, intact roots decompose fairly rapidly in soil (<6 weeks), and there is potential for substantial losses of soil NO − [over] 3 as a result of denitrification at soil water contents ≥70%.

A prospective controlled study of diagnostic imaging for acute shin splints. Med. Sci. Sports Exerc.,Vol. 30, No. 11, pp. 1564-1571, 1998.

Pulmonary edema is a debilitating effect of acute respiratory distress syndrome. The ability to measure it noninvasively with high sensitivity and in three dimensions could be useful in not only detection but also in assessment and guidance of treatment. To this end, a three‐dimensional MRI pulse sequence to measure the formation of edema was developed and tested. Another sequence was tested to measure blood flow in distal pulmonary arteries. Pulmonary edema was induced in nine dogs via venous injections of oleic acid. Edema was verified by wet‐to‐dry weight ratio (5.30 ± .38) and extravascular lung water at baseline (2.03 ± 1.12 ml/g dry lung weight) versus postinjury (3.00 ± 1.45 ml/g) (P< .005). The signal‐to‐noise ratio within the lungs increased from 5.47 ± 1.00 at baseline to 7.51 ± 1.96 (P< .005), and the time course of edema formation was resolved. Results from MR phase‐contrast blood flow measurements were variable. The authors conclude that the three‐dimensional scan provides a sensitive relative quantification of pulmonary edema formation without the use of contrast agents or ionizing radiation.

Polyphenol oxidase (PPO) has been related to an undesirable brown discoloration of wheat-based end products. Consumer acceptance and product quality are generally decreased by the darkening phenomena. Two sets of wheat samples (Triticum aestivumL.) were investigated for variation in grain and flour PPO levels. Samples included 40 advanced experimental hard white winter wheat lines grown at two Kansas locations and 10 hard red winter wheat genotypes grown at three Nebraska locations. The variability in grain and flour PPO activities was influenced by growing location and population for the hard white wheat samples. There also was a significant influence of population by growing location interactions on PPO activity in both grain and flour. Genotype and growing location both contributed to variability in flour PPO activity among the hard red wheat samples. The variation in flour PPO activities among growing locations appeared larger than variation produced by genotypes tested for the hard red wheat samples. Quality parameters, such as wheat physical properties, flour protein and ash contents, grain color, and milling yield significantly correlated with grain and flour PPO activities. Among red wheat samples, flour PPO activity was related to 100 kernel weight, first reduction flour yield, and flour ash content. Grain PPO activity was related to variation in grain color observed among hard white samples. The relationship of quality characteristics with grain and flour PPO activities varied among white and red wheat samples.

We investigated the feasibility of performing black‐blood MR angiography (MRA) with the gradient and spin‐echo (GRASE) pulse sequence. Phantom experiments and human testing were conducted, and the results were compared with those of turbo spin‐echo (TSE). We demonstrated that both techniques are able to produce signal suppression of flowing fluid to background level. With fewer radiofrequency (RF)‐refocusing pulses, GRASE pulse sequences could serve as an alternative black‐blood technique of reduced RF power exposure and shorter scan time. These relative advantages of GRASE may become useful when high‐resolution images are taken.

An expression for the off-resonance vibrational contribution to the hyperpolarizability of a homonuclear diatomic molecule is derived. This expression is written in terms of the Raman transition polarizability, and it explicitly gives the frequency dependence of all the independent tensor components of the hyperpolarizability of a randomly oriented, freely rotating molecule. The vibrational contributions to the hyperpolarizabilities of several molecules are evaluated and compared, both in the static limit, and also at optical frequencies. Several nonlinear optical processes are considered.

The two-body collision-induced scattering spectra of CH4, CD4, CF4 and SF6 are presented. They are shown to contain features due to collision-induced rotational Raman scattering (CIRS). The spectra are used to obtain estimates of the magnitude of the molecular polarizabilities A (dipole-quadrupole) and E (dipole-octopole). The zeroth moment of the translational CIS spectrum also provides further evidence that the pair polarizability β(r) may be accurately described by the point dipole-induced-dipole (DID) model with small dispersion corrections.

A four-trial experiment utilizing 3- to 4-wk-old newly weaned pigs was conducted to evaluate the effect of a modified reduced nocturnal (MRNT) nursery temperature regimen on weaned pig and subsequent grower-finisher performance. Nursery treatments were 1) a control temperature (CT) regimen of 30°C constant air temperature lowered 2 C°/wk and 2) a regimen beginning 1 wk after weaning in which the temperature from 1900 to 0700 was lowered 6°C from CT. Weaned pigs gained faster (P< .01) in the MRNT treatment than in the CT treatment, with gains in Trials 1, 2, 3 and 4 being .39 vs .37, .28 vs .27, .38 vs .37 and .39 vs .36 kg/d, respectively. This improvement in gain was due to an increase (P< .005) in feed intake for the same periods (.60 vs .58; .48 vs .42; .59 vs .58; .63 vs .58 kg/d). There was no difference in feed conversion (P> .1). There was no effect (P> .1) of MRNT vs CT on subsequent performance to slaughter weight for average daily gain (.69 vs .69 kg/d), average daily feed (2.22 vs 2.23 kg/d) or gain/feed (.31 vs .31). These results support the conclusions that weaned pigs eat more feed and gain faster with a reduced nocturnal temperature scheme and that there are no carry-over effects during the growing-finishing phase.

Three clones of Spirodela polyrhizaL. (Schleid.) formed dormant bodies called turions. A clone from Puerto Rico did not form turions under all conditions tried. In those clones producing turions, formation was stimulated by the addition of sucrose (10–50 mM) to the nutrient solution. Increased levels of Ca(NO3)2plus sucrose stimulated turion production. In the absence of NO3–, Ca++was more effective than K+in stimulating turion formation. Turion buoyancy was not light dependent, nor was it promoted by sucrose. Normal turions required light for germination, whereas sucrose‐induced turions germinated in the dark. Dark germination was not promoted by either Ca++or K+. Sucrose stimulation of turion formation and subsequent promotion of dark germination was attributed to metabolic rather than osmotic effects. One hundred mM sucrose concentrations inhibited turion buoyancy and germination. Turions formed one primary abscission layer which separated them from the stolon and the mother frond. Subepidermal idioblasts appeared to seal the stolon stump after separation.

Experiments were conducted to assess the ability of Streptomyces (strain PS1/5) to metabolize twelve herbicides representing several different classes including: acetanilides, triazines, ureas, uracils, and imidazoles. Incubations in aqueous culture with dextrin as carbon source and either ammonium or Casamino acids as nitrogen source resulted in transformations (>50%) of eight of the herbicides tested: alachlor, metolachlor, atrazine, prometryne, ametryne, linuron, tebuthiuron, and bromacil; the remaining four herbicides (cyanazine, diuron, metribuzin, and imazapyr) were also transformed, but to a lesser extent. In most instances, biotransformations occurred concurrently with growth and results were consistent regardless of the nitrogen source (ammonium vs. Casamino acids). However, in some instances there were differences in rates of biotransformation as a consequence of the nitrogen source (e.g. alachlor, metribuzin), suggesting the selective induction of certain metabolic enzymes; in other instances biotransformations were not associated with growth, suggesting secondary metabolism. An experiment was also conducted to assess the ability of Streptomyces (strain PS1/5) to metabolize atrazine contaminated soil. Inoculation of soil amended with 20 µg/g of atrazine and 5% chitin as carbon source resulted in ca. 78% removal of atrazine within 28 days. These data suggest that Streptomyces species may be potential candidates for soil inoculation to bioremediate herbicide contaminated soils.