Lemna

Mekenyan OG, Bonchev DG, Enchev VG. Modeling the interaction of small organic molecules with biomacromolecules (the Oasis approach). V. Toxicity of phenols to algae Lemna minor . Quant Struct-Act Relat 1988 7 240-4. 

Isomers of D-apiofuranosyl 1-phosphate have been prepared by treating a mixture of jS-o-apio-D-furanosyl and /3-D-apio-L-furanosyl tetra-acetates with crystalline phosphoric acid. a-o-Apio-o- (59) and a-o-apio-L-furanosyl-1-phosphate (60) and their cyclic phosphates were separated by chromatography and identified by H n.m.r. o-Apiose is metabolized in parsley and Lemna minor with the possible formation of UDP-D-apiose. L. minor will convert UDP-a-glucuronic acid into a-o-apio-D-furanosyl-1,2-cyclic phosphate (61) but no evidence of UDP-o-apiose was found, although it is possible that (61) arose from the rapid hydrolysis of UDP-o-apiose. 

Hart, D.A. and Kindel, P.K. (1970) Isolation and partial characterization of apiogalacturonans from the cell wall of Lemna minor. BiochemJ. 116 569-579. 

Increased the sensitivity of this bloassay to 0.5 nM concentrations of allelochemlcals. The Lemna assays were also useful for determining bloactlve fractions extracted from allelopathic plants. 

Other kinds of bloassays have been used to detect the presence of specific allelochemical effects (8), effects on N2 fIxatlon (9), the presence of volatile compounds (10) and of Inhibitory substances produced by marine microalgae (11). Putnam and Duke (12) have summarized the extraction techniques and bioassay methods used In allelopathy research. Recent developments In high performance liquid chromatography (HPLC) separation of allelochemlcals from plant extracts dictates the need for bloassays with sensitivity to low concentrations of compounds contained In small volumes of eluent. Einhellig at al. (13) described a bloassay using Lemna minor L. growing In tissue culture cluster dish wells that maximizes sensitivity and minimizes sample requirements. 

Additional research with Lemna species has indicated that parameters other than direct growth measurements may be more sensitive In this bioassay. Table VII compares growth and chlorophyll content of L. minor as affected by catechln. Final frond number was inhibited by 1000 pM catechln and stimulated at lower concentrations of 50 and 100 pM. Chlorophyll content on a per-frond basis, however, was consistently Inhibited by catechln and was concentration dependent to 100 pM. 

Lemna obscura fronds contain high quantities of anthocyanln that are extractable by soaking the fronds In 0.1 M HC1. L. obscura growth in the culture dish bloassay was similar to that of L. minor and appeared to be more sensitive to low levels of allelochemlcals. Anthocyanln concentration was affected by low concentrations of salicylic acid (Table VIII). Final frond number and dry weight were consistently reduced by 100 pM and 500 pM concentrations of salicylic acid whereas anthocyanln formation was inhibited by 50 UM concentrations of salicylic acid and stimulated by 0.5 VM. 

TABLE VII. Effect of Catechln on the Growth and Chlorophyll Content of Lemna minor L. Growing In 24-well Tissue Culture Cluster Dishes... 

Activity has been detected In the Lemna bloassay with HPLC fractions of unknown allelochemlcals from sunflower using quantities as low as 5 pi of a 28 ppm w/v solution (see Saggese et al. this publication). 

Recent reports on biosorbents based on diverse types of macrophytes are found widely in the literature. Free-floating aquatic plants from the genera Salvinia, Azolla, Eichhornia, Lemna, and Pistia have been described the most. S. natans biomass was able to uptake As(V) at low initial concentrations from 0.25 to 2 mg/L (74.8% and 54%, respectively). The experimental data fitted well to both Langmuir and Freundlich isotherms. The effect of pH and biomass quantities on sorption rate has also been investigated along with some metabolic parameters.105... 

Hurd, N.A. and Sternberg, S.P.K., Bioremoval of aqueous lead using Lemna minor, International Journal of Phytoremediation, 10 (4), 278-288, 2008. 

John, R., Ahmad, P., Gadgil, K., and Sharma, S., Effect of cadmium and lead on growth, biochemical parameters and uptake in Lemna polyrrhiza L., Plant Soil and Environment, 54 (6), 262-270, 2008. 

Rakhshaee, R., Giahi, M., and Pourahmad, A., Studying effect of cell wall s carboxyl-carboxylate ratio change of Lemna minor to remove heavy metals from aqueous solution, Journal of Hazardous Materials, 163 (1), 165-173, 2009. 

Sharma H, Barber JT, Ensley HE, Polito MA (1997) A comparison of the toxicity of phenol and chlorinated phenols by Lemna gibba with reference to 2,4,5-trichloorophenol. Environ Toxicol Chem 16 346—350... 

We can rephrase the previous lemna to provide in effect a syntactic definition of what it means for a path to be an execution sequence. If we are given any path s fran START through a scheme P, we can build the sets Q(s,T,0) and Q(s,T,l) for each test T as before. We construct the various values val (u,j) as before following s and place t in Q(s,T,j) when demanded by the algorithm, step (3), but do not worry as to whether this is a consistent definition. As before, this is an actual construction only for s finite. 

Finally assume that e is directly connected to nodes n and m and that e cycle dominates neither n nor m. By Lemna 4.9, e cannot chain dominate both n and m so suppose e does not chain dominate m. By the definition of linelike, there is a node p such that e chain dominates p and p back dominates m and hence n. Suppose there is more than one such node p. The set of nodes... 

Simple plants Physcomitrella patens Chlamydomonas reinhardtii Lemna minor Containment, clonal propagation, batch consistency, secretion of proteins into medium, regulatory compliance, homologous recombination in Physcomitrella Scalability... 

Certain emergent aquatic plants, especially hydrilla (Hydrilla verticillata) and duckweed (Lemna obscura), removed 97 to 98% of all soluble lead from solution in the vicinity of a lead battery site in Tampa, Florida, suggesting that phytoremediation may be feasible as the basis of a lead removal technology (Gallardo et al. 1999). 

Duckweed, Lemna media 30 Reduced growth in 10 days 31... 

Beaumont, G., A. Lord, and G. Grenier. 1980. Effets physiologiques de 1 atrazine a doses subletales sur Lemna minor. V. Influence sur 1 ultrastructure des chloroplastes. Canad. Jour. Bot. 58 1571-1577. 

Grenier, G., L. Protean, J.P. Marier, and G. Beaumont. 1987. Effects of a sublethal concentration of atrazine on the chlorophyll and lipid composition of chlorophyll-protein complexes of Lemna minor. Plant Physiol. Biochem. 25 409-413. 

Huber, W., V. Schubert, and C. Sautter. 1982. Effects of pentachlorophenol on the metabolism of the aquatic macrophyte Lemna minor L. Environ. Pollut. 29A 215-223. 

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