Phylogenetic systematic evaluation of a classification of the Zoogonidae Odhner, 1902 (Cercomeria: Trematoda: Digenea: Plagiorchiiformes)

A recent systematic study of the digenean family Zoogonidae presented a series of cladograms, which are the product of phylogenetic systematic, or cladistic, analysis. However, one of the two subfamilies and nine of the 21 genera recognised in that study lacked putative synapomorphies, a requirement for phylogenetic systematic studies. This study presents a re-analysis of the database for the zoogonids, based on rigorous application of phylogenetic systematic methods. A new phylogenetic tree is presented, which better fits the original data than the published tree (with a consistency index of 52.3% vs. 46.3%). Four subfamilies, three monophyletic and one of uncertain status, and 10 genera could be recognised phylogenetically. This would affect the nomenclatorial status of one-third (26) of the species in the family. However, it is recommended that another analysis, based on more characters, be carried out before nomenclatorial changes are proposed.     

Endogenous nitric oxide decreases xanthine oxidase-mediated neutrophil adherence: role of P-selectin

Terada, Lance S., John E. Repine, Dale Piermattei, andBrooks M. Hybertson. Endogenous nitric oxide decreases xanthine oxidase-mediated neutrophil adherence: role of P-selectin.J. Appl. Physiol. 82(3): 913-917, 1997.The oxygen radical-producing enzyme xanthine oxidase (XO) canpromote neutrophil adherence to endothelium. Recognizing that a balanceoften exists in inflammatory processes, we sought to determine whetherXO initiates antiadherent pathways. We found that bovine pulmonaryarterial endothelial cells (EC) exposed to XO released increasedamounts of nitrite into the media, reflecting an increased productionof nitric oxide (NO). When EC were subjected to shear stress, treatmentwith XO and/or the NO synthase inhibitorN-nitro-L-arginine(L-NNA) increased neutrophilrolling behavior and firm neutrophil adherence to EC in an additivefashion. Both rolling and adherent interactions were abolished bymonoclonal antibodies directed against P-selectin. In addition,treatment of EC with XO and/orL-NNA increased both surfaceexpression of P-selectin and release of von Willebrand factor intomedia. Finally, treatment of EC with the NO donor sodium nitroprussidedecreased XO-mediated neutrophil rolling and adherence. We concludethat XO stimulates EC to produce NO and that NO decreases theP-selectin-dependent neutrophil adhesion initiated by XO. Suchincreases in endogenous NO may constitute an importantnegative-feedback response to the acute proadhesive effects of XO.

     

Copper and cobalt in African species ofAeolanthus Mart. (Plectranthinae,Labiatae)

Summary Hyperaccumulators (here defined as species containing at least 500 μg/g dryweight of either copper or cobalt in leaves), are of interest for the fields of mineral exploration and phytochemistry. Reported hyperaccumulation of copper inAeolanthus biformifolius and the presence of two other species on copper/cobalt mineralization in Shaba (Za?re) led to a survey of these elements in 49 species of the African genusAeolanthus Mart.A. biformifolius appears to be also a hyperaccumulator of Co (2520 μg/g in leaves, 4300 μg/g in corms). Cobalt levels for most species ofAeolanthus were considerably above typical values for phanerogams and indicate the favorable potential of the genus for further study.     

Design of laboratory continuous-culture equipment for accurate gaseous metabolism measurements

The accuracy of kinetic and stoichiometric data obtained from most laboratory-scale continuous-culture equipment, particularly involving gaseous measurements, may be much lower than many workers realize, despite the use of good quality instruments. For example, errors in specific oxygen uptake measurements (QO(2)) easily can be as high as +/-100%. This article assesses the accuracies of individual instruments and of the overall system in greater detail than has previously been reported and suggestions are made as to how the errors can be reduced to acceptable levels.     

Amplification of D-xylose and D-glucose isomerase activities in Escherichia coli by gene cloning

A recombinant plasmid, designated pUC1002, was constructed by ligation of a HindIII restriction endonuclease fragment of Escherichia coli chromosomal DNA to vector plasmid pMB9. Strains carrying this plasmid were selected by transformation of an E. coli strain bearing the xyl-7 mutation to a xylose-positive (Xyl+) phenotype. Strains containing pUC1002 produced coordinately elevated levels of D-xylose isomerase and D-xylulose kinase. Under appropriate conditions, the isomerase also efficiently catalyzed the conversion of D-glucose to D-fructose.