Potential phylogenetic utility of the low-copy nuclear gene pistillata in dicotyledonous plants: comparison to nrDNA ITS and trnL intron in Sphaerocardamum and other Brassicaceae.

We report the potential phylogenetic utility of DNA sequence data from the last 700 bp of a ca. 1-kb intron of the MADS-box gene pistillata from a sampling of Sphaerocardamum species and other Brassicaceae. These results are compared with nrDNA ITS and the chloroplast trnL intron for the same taxa to demonstrate the potential phylogenetic utility of this pistillata intron and to identify potential historically independent sequences for an ongoing study of relationships within Sphaerocardamum. Analyses of the DNA sequence data for Brassicaceae indicated that pairwise divergences and potentially informative characters were higher in the pistillata intron (0.6-30.8%, 284 characters) and ITS (0-24%, 94 characters) than in the chloroplast trnL intron (0-4.2%, 17 characters). A comparison of Sphaerocardamum sequences identified low divergences and numbers of informative characters for trnL intron (0-2.4%, 1 character) and nrDNA ITS (0-2.5%, 2 characters) and substantially more variation among the pistillata sequences (0.15-3.7%, 19 characters). Phylogenetic analyses of these pistillata sequences fully resolve ingroup relationships without character conflict. Results of pistillata PCR amplifications from a broader dicot sample showed that some primers may be useful in amplifying orthologous pistillata sequences. Ultimately this pistillata intron may be a valuable source of phylogenetic characters at lower taxonomic levels.     

Effects of wheat germ agglutinin on tunicate egg activation and fertilization: Is there a plasma membrane sperm receptor system on Ascidia ceratodes eggs?

Little work has been carried out on the sperm recognition systems present on the egg plasma membrane. Here it is shown that wheat germ agglutinin (WGA) interferes with the sperm-interacting system on the plasma membrane of eggs of the ascidian, Ascidia ceratodes. The WGA activates the dechorionated egg, indicating that a plasma membrane sugar residue can be directly tied to egg activation. Low concentrations of this lectin do not activate the eggs, but reduce fertilizability. This observation suggests that the WGA binding site might be part of a sperm reception–activation complex in the plasma membrane. While WGA also affects sperm binding to the chorion, the mechanisms of sperm interaction at the plasma membrane and chorion show different sensitivities to lectins, sugars and enzymes.     

Speciation and the evolution of behaviour in prosimians

A mechanism is suggested, based on a biphasic approach-withdrawal theory proposed byT. C. Schneirla, to account for how behaviours may be selected by environmental forces for transmission over generations. The basic postulates of Schneirla's theory are presented followed by an examination of some aspects of lorisid behaviour in the light of this theory.     

Mass Mediations: New Approaches to Popular Culture in the Middle East and Beyond; New Media in the Muslim World: The Emerging Public Sphere

Mass Mediations: New Approaches to Popular Culture in the Middle East and Beyond. Walter Armbrust. ed. Berkeley. University of California Press, 2000. 378 pp.
New Media in the Muslim World: The Emerging Public Sphere. Dale Eickelman and Jon W. Anderson. eds. Bloomington: Indiana University Press, 1999. 213 pp.     

Isolation and characterization of a Mr = 110,000 glycoprotein localized to the hepatocyte bile canaliculus

A Mr = 110,000 glycoprotein, GP 110, was partially purified using wheat germ agglutinin-Sepharose affinity chromatography from a bile canalicular-enriched membrane fraction denoted N2u of rat liver. This fraction was subjected to preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the Mr = 110,000 polypeptide was excised and used as an immunogen in rabbits. The antisera were found to specifically recognize a Mr = 110,000 polypeptide, named GP 110, in the N2u membrane fraction. In isolated hepatocytes, GP 110 was readily accessible to cell surface iodination catalyzed by lactoperoxidase at 4 degrees C and was judged by immunoprecipitation studies to contain about 2% of total radioactivity incorporated into externally oriented proteins of the cell. Immunoprecipitated GP 110 was shown by two-dimensional polyacrylamide gel electrophoresis to migrate with an approximate pI of 4.9. Indirect immunofluorescence on frozen liver sections demonstrated that GP 110 was primarily localized in the bile canaliculus. In corroborative studies employing subcellular fractionation, it was found that GP 110 was enriched nearly 19-fold in P2, a plasma membrane fraction primarily derived from the sinusoidal domain, and 44-fold in N2u. In contrast, only low levels of GP 110 were present in endoplasmic reticulum, mitochondrial, cytosolic, and nuclear-enriched fractions of liver. The physiological function of GP 110 is as yet unknown; antisera to it did not immunoprecipitate other known bile canalicular proteins of similar molecular weights. GP 110 was found to be extensively glycosylated relative to other known membrane proteins; approximately 33% of the apparent molecular weight appear to be carbohydrate. In agreement, limited removal of N-linked carbohydrate chains indicated that there are approximately eight chains/GP 110 polypeptide. Neuraminidase treatment of GP 110 resulted in a desialylated Mr = 85,000 polypeptide suggesting that the majority of carbohydrate chains on GP 110 are of the complex type.     

The effect of alkaline borohydride treatment onN-linked carbohydrates of glycoproteins

The effects of treatments of the glycoprotein ribonuclease-B, the proteins ribonuclease-A and myoglobin, and the glyco-amino acid GlcNAc(1-N) Asn with alkalil alkaline sodium borohydride, and aqueous sodium borohydride were systematically studied as a function of the concentration of the reagents, the temperature, and the length of the treatment. High-field¹H-NMR spectroscopy, chromatographic methods and amino-acid analysis were used to characterize products of the treatments of the various compounds. Our results indicate that mild alkaline borohydride treatment, as well as aqueous borohydride treatment alone, is capable of extensively degrading polypeptides and of partially releasing theN-linked glycans from ribonuclease-B. Initially, glycopeptides are produced, the peptide portion of which consists of several amino acids, which are further hydrolyzed to yield a mixture of glyco-asparagines and oligosaccharide-alditols in the ratio of 4:1. Strong alkaline borohydride treatment of ribonuclease-B is capable of completely releasing theN-linked carbohydrates as oligosaccharide-alditols.Abbreviation RNase ribonuclease     

Binding of a radiolabeled sea anemone cytolysin to erythrocyte membranes

Stichodactyla helianthus cytolysin III, a 17 kDa basic polypeptide isolated from a Caribbean sea anemone, is one of the most potent hemolysins yet found in a living organism. This toxin has been reported to form new ion channels in artificial lipid bilayer membranes. The ability of this toxin to attack cell membranes is greatly enhanced by the presence of sphingomyelin. In order to investigate the mechanism by which the cytolysin causes cell lysis, we have prepared a highly active [3H]cytolysin derivative by reductive methylation with sodium cyanoborohydride and [3H]formaldehyde. A dimethylated toxin derivative was used to investigate the basis for the differential lytic activity of this polypeptide upon erythrocytes from six mammalian species. Using both direct [3H]toxin binding and indirect (Thron method) binding techniques, we found that the interspecies differences are due to variable membrane susceptibilities toward the bound toxin, rather than to differences in membrane affinity for the toxin. Similarly, we showed the enhanced lytic activity of the toxin for rat erythrocytes at elevated pH to be caused by enhanced activity of the bound toxin.     

Sodium lactate delays toxin production by Clostridium botulinum in cook-in-bag turkey products.

Comminuted raw turkey, containing 1.4% sodium chloride, 0.3% sodium phosphate, and 0 (control), 2.0, 2.5, 3.0, or 3.5% sodium lactate, was inoculated with a 10-strain mixture of proteolytic type A and B Clostridium botulinum spores. The inoculated turkey was vacuum packaged and cooked by immersion in heated water to an internal temperature of 71.1 degrees C. Samples were incubated at 27 degrees C for up to 10 days. Five samples per treatment were examined for botulinal toxin at specific intervals. Sodium lactate exhibited an antibotulinal effect which was concentration dependent. Processed turkey containing 0, 2.0, 2.5, 3.0, or 3.5% sodium lactate was toxic after 3, 4 to 5, 4 to 6, 7 or 7 to 8 days, respectively. Subsequent studies with a broth medium revealed that lactate, not the sodium ion, was the principal factor in delaying botulinal-toxin formation.     

Fate of Listeria monocytogenes in processed meat products during refrigerated storage.

The fate of Listeria monocytogenes during refrigerated storage was determined on several processed meat products, including ham, bologna, wieners, sliced chicken, sliced turkey, fermented semidried sausage, bratwurst, and cooked roast beef. The meats were surface inoculated with a five-strain mixture of less than or equal to 200 or ca. 10(5) L. monocytogenes cells per package, vacuum packaged, and stored at 4.4 degrees C. Survival or growth of listeriae was determined for up to 12 weeks of storage or until the product was spoiled. The organism survived but did not grow on summer sausage, grew only slightly on cooked roast beef, grew well on some wiener products but not on others, grew well (10(3) to 10(5) CFU/g increase within 4 weeks) on ham, bologna, and bratwurst, and grew exceptionally well (10(3) to 10(5) CFU/g increase within 4 weeks) on sliced chicken and turkey. The rate of growth depended largely upon the type of product and the pH of the product. Growth was most prolific on processed poultry products. The organism generally grew well on meats near or above pH 6 and poorly or not at all on products near or below pH 5. These results indicate the importance of preventing postprocessing contamination of L. monocytogenes in a variety of ready-to-eat meat products.