The synthesis and cytotoxic activity of some haloacetamidoalkyl β-D-xylopyranosides

2-Hydroxyethyl 2,3,4-tri-O-acetyl-β-D-xylopyranoside was prepared from 2,3,4-tri-O-acetyl-α-D-xylopyranosyl chloride by the action of 1,2-ethanediol and mercuric acetate. Subsequent mesylation and azide displacement gave 2-azidoethyl 2,3,4-tri-O-acetyl-β-D-xylopyranoside, which was hydrogenated over palladiumon-charcoal and the amine acylated with various haloacetyl halides, to afford 2-(haloacetamido)ethyl 2,3,4-tri-O-acetyl-β-D-xylopyranosides. Deprotection to obtain the free sugars was carried out with 5mM ethanolic sodium ethoxide. 2-(Chloroacetamido)ethyl 2,3,4-tri-O-acetyl-β-D-xylopyranoside was further modified by sequential azide displacement, hydrogenation, and subsequent acylation with various haloacetyl halides to afford 2-[(haloacetamido)acetylamino]ethyl 2,3,4-tri-O-acetyl-β-D-xylopyranosides, which were also deprotected to give the corresponding free sugars. The effects of these haloacetamido analogs on the growth of the melanoma cells in tissue culture was evaluated.     

Effects of initial surface wettability on biofilm formation and subsequent settlement of Hydroides elegans

Hydroides elegans is a major fouling organism in tropical waters around the world, including Pearl Harbor, Hawaii. To determine the importance of initial surface characteristics on biofilm community composition and subsequent colonization by larvae of H. elegans, the settlement and recruitment of larvae to biofilmed surfaces with six different initial surface wettabilities were tested in Pearl Harbor. Biofilm community composition, as determined by a combined approach of denaturing gradient gel electrophoresis and fluorescence in situ hybridization, was similar across all surfaces, regardless of initial wettability, and all surfaces had distinct temporal shifts in community structure over a 10 day period. Larvae settled and recruited in higher numbers to surfaces with medium to low wettability in both May and August, and also to slides with high wettability in August. Pearl Harbor biofilm communities developed similarly on a range of surface wettabilities, and after 10 days in Pearl Harbor all surfaces were equally attractive to larvae of Hydroides elegans, regardless of initial surface properties.     

Estimating evolutionary parameters when viability selection is operating

Some individuals die before a trait is measured or expressed (the invisible fraction), and some relevant traits are not measured in any individual (missing traits). This paper discusses how these concepts can be cast in terms of missing data problems from statistics. Using missing data theory, I show formally the conditions under which a valid evolutionary inference is possible when the invisible fraction and/or missing traits are ignored. These conditions are restrictive and unlikely to be met in even the most comprehensive long-term studies. When these conditions are not met, many selection and quantitative genetic parameters cannot be estimated accurately unless the missing data process is explicitly modelled. Surprisingly, this does not seem to have been attempted in evolutionary biology. In the case of the invisible fraction, viability selection and the missing data process are often intimately linked. In such cases, models used in survival analysis can be extended to provide a flexible and justified model of the missing data mechanism. Although missing traits pose a more difficult problem, important biological parameters can still be estimated without bias when appropriate techniques are used. This is in contrast to current methods which have large biases and poor precision. Generally, the quantitative genetic approach is shown to be superior to phenotypic studies of selection when invisible fractions or missing traits exist because part of the missing information can be recovered from relatives.