Phylogenetics of Asphodelaceae (Asparagales): An Analysis of Plastid rbcL and trnL-F DNA Sequences

Phylogenetic relationships of Asphodelaceae were investigatedby parsimony analysis of 57 monocotrbcL nucleotide sequences,including 17 genera that have at some time been assigned tothe family. All genera of Asphodelaceae except for three (Hemiphylacus,Paradisea and Simethis) form a strongly supported monophyleticgroup with Hemerocallidaceae and Xanthorrhoeaceae as their immediatesister taxa. In a second analysis, we added 34 plastid trnL-Fsequences (an intron and a spacer between two transfer RNA genes)for the Asphodelaceae clade and nearest outgroup families (Doryanthaceae,Hemerocallidaceae, Iridaceae, Ixioliriaceae, Tecophilaeaceaeand Xanthorrhoeaceae) in an attempt to improve resolution andlevels of internal support. The results from the separate analysesproduced highly similar although not identical results. No stronglysupported incongruent groups occurred, and we combined bothsequence regions in one analysis, which demonstrated improvedresults. Strong support exists for a monophyletic subfamilyAlooideae, but this leaves a paraphyletic subfamily Asphodeloideaebecause Bulbine/Jodrellia alone are strongly supported as thesister group of Alooideae. Characters that have been used toseparate Alooideae as a distinct group (either as here a subfamilyor as a separate family by other authors), such as secondarygrowth and bimodal karyotypes, are found in at least some membersof Asphodeloideae, particularly in Bulbine and Jodrellia forthe karyotypes, making Alooideae less easily recognized. Copyright2000 Annals of Botany Company Alooideae, Asphodeloideae, Asphodelaceae, Asparagales, phylogenetic analysis, rbcL, trnL-F, molecular systematics     

Transformation of 2,4,6-Trinitrotoluene by Purified Xenobiotic Reductase B from Pseudomonas fluorescens I-C

The enzymatic transformation of 2,4,6-trinitrotoluene (TNT) by purified XenB, an NADPH-dependent flavoprotein oxidoreductase from Pseudomonas fluorescens I-C, was evaluated by using natural abundance and [U-¹⁴C]TNT preparations. XenB catalyzed the reduction of TNT either by hydride addition to the aromatic ring or by nitro group reduction, with the accumulation of various tautomers of the protonated dihydride-Meisenheimer complex of TNT, 2-hydroxylamino-4,6-dinitrotoluene, and 4-hydroxylamino-2,6-dinitrotoluene. Subsequent reactions of these metabolites were nonenzymatic and resulted in predominant formation of at least three dimers with an anionic m/z of 376 as determined by negative-mode electrospray ionization mass spectrometry and the release of ~0.5 mol of nitrite per mol of TNT consumed. The extents of the initial enzymatic reactions were similar in the presence and in the absence of O₂, but the dimerization reaction and the release of nitrite were favored under aerobic conditions or under anaerobic conditions in the presence of NADP⁺. Reactions of chemically and enzymatically synthesized and high-pressure liquid chromatography-purified TNT metabolites showed that both a hydroxylamino-dinitrotoluene isomer and a tautomer of the protonated dihydride-Meisenheimer complex of TNT were required precursors for the dimerization and nitrite release reactions. The m/z 376 dimers also reacted with either dansyl chloride or N-1-naphthylethylenediamine HCl, providing evidence for an aryl amine functional group. In combination, the experimental results are consistent with assigning the chemical structures of the m/z 376 species to various isomers of amino-dimethyl-tetranitrobiphenyl. A mechanism for the formation of these proposed TNT metabolites is presented, and the potential enzymatic and environmental significance of their formation is discussed.     

Citrus products—A quarter century of amazing progress

Highly specialized factories affiliated with the California Fruit Growers Exchange, an orange-, lemon-and grapefruit-marketing cooperative of 14,500 California and Arizona growers, produce tremendous quantities of citrus products which find uses not only in foods but in fields as diverse as medicine and the oil and rubber industries.