Responses of the Crab <Emphasis Type="Italic">Heterozius rotundifrons</Emphasis>to Heterospecific Chemical Alarm Cues: Phylogeny vs. Ecological Overlap

The big-handed brachyuran crab Heterozius rotundifronsextends the time spent in its anti-predator posture, limb extended posture, if exposed to chemical cues from crushed conspecifics. In this study, we tested whether crabs also respond to chemical cues from crushed heterospecific crabs, and if so, whether phylogenetic relations or ecological overlap is more important in influencing the duration of the anti-predator posture. Chemical cues from two other brachyuran crabs (Cyclograpsus lavauxi and Hemigrapsus sexdentatus), which do not overlap directly in ecological distribution with H. rotundifrons, elicited a duration of the anti-predator posture that was indistinguishable from that produced by conspecific chemical cues. In contrast, chemical cues from two anomuran crabs (Petrolisthes elongatus and Pagurus novizealandiae) that overlap in ecological distribution with H. rotundifrons, elicited durations of the antipredator posture that were significantly shorter than those of either conspecifics or more closely related crab species. Thus, phylogenetic relationship seems to be more important than ecological overlap in influencing anti-predator behavior in H. rotundifrons.     

Group sequential testing in dental clinical trials with longitudinal data on multiple outcome variables

In this article, methods are proposed for design and analysis of clinical trials that gather longitudinal data on multiple outcome variables. A valid test of the null hypothesis of no treatment group differences can be obtained for any choice of a working alternative hypothesis and a working covariance matrix for the outcome variables. Increased power can be achieved by accurate modeling of the true treatment effect and covariance structure. Implementation of the procedure is simple using existing software for generalized estimating equations. The procedure is an extension of the 'derived variable' technique (univariate analysis applied to a linear combination of the outcome variables) and also of O'Brien's generalized least squares test. The procedure is extended to allow sequential testing using an arbitrary division of the total type I error rate among repeated hypothesis tests. The methods are illustrated by the design of a study on the safety of dental amalgam fillings, which served as the motivation for the research.     

Convenient access both to highly antimalaria-active 10-arylaminoartemisinins, and to 10-alkyl ethers including artemether, arteether, and artelinate

An economical phase-transfer method is used to prepare 10-arylaminoartemisinins from DHA and arylamines, and artemether, arteether, and artelinate from the corresponding alcohols. In vivo sc screens against Plasmodium berghei and P. yoelii in mice reveal that the p-fluorophenylamino derivative 5 g is some 13 and 70 times, respectively, more active than artesunate; this reflects the very high sc activity of 10-alkylaminoartemisinins. However, through the po route, the compounds are less active than the alkylaminoartemisinins, but still approximately equipotent with artesunate.     

A TAT-streptavidin fusion protein directs uptake of biotinylated cargo into mammalian cells

The HIV-1 TAT peptide has been used extensively for directing the intracellular delivery of an assortment of cargo, including DNA, liposomes and macromolecules. For protein delivery, a variety of TAT-fusion proteins have been described which link the TAT coding sequence to the protein coding sequence of interest. Streptavidin represents a potentially useful TAT-fusion protein because it could be used to deliver a wide array of biotinylated cargo. Here we have characterized a TAT-streptavidin (TAT-SA) fusion protein, which retains the ability to bind biotinylated cargo while directing their efficient cellular uptake. Fluorescence activated cell sorting (FACS) analysis and confocal microscopy characterization showed that TAT-SA is internalized by Jurkat T-cells and NIH 3T3 cells alone and when complexed to phycoerythrin, whereas the native streptavidin is not. Additionally, biotinylated alkaline phosphatase is successfully internalized and retains its activity when complexed to TAT-SA and incubated with Jurkat T-cells. Confocal microscopy suggested, however, that internalized TAT-SA and TAT-SA complexes were largely compartmentalized in vesicular compartments, rather than freely diffusing in the cytoplasmic compartment. To effect cytoplasmic delivery, the endosomal releasing polymer, poly(propylacrylic acid) (PPAA), was biotinylated and complexed to TAT-SA. Endosomal release and cytoplasmic delivery of fluorescently labeled TAT-SA complexes with PPAA was shown by the diffuse distribution of fluorescent protein in the cytoplasm. Taken together, these results demonstrate that TAT-SA can be used to direct intracellular delivery of large biotinylated cargo to intracellular compartments and that biotinylated PPAA can direct cytoplasmic delivery where desired.     

Methods for characterizing plant fibers

The effectiveness of different microscopy techniques for measuring the dimensions of ultimate fibers from harakeke (Phormium tenax, New Zealand flax) was investigated using a factorial experimental design. Constant variables were geographical location, location of specimens along the leaf, season (winter), individual plant, a fourth leaf from a north-facing fan, age of plant, and cultivars (two). Experimental variables were microscopy techniques and measurement axis. Measurements of width and length of harakeke ultimate fibers depended on the microscopic preparation/technique used as well as the cultivar examined. The best methods were (i) transverse sections of leaf specimens 4 microm thick, embedded in Paraplast and observed using light microscopy, and (ii) nonfixed ultimate fibers observed using scanning electron microscopy.     

Regional differences in collagen stable isotope and tissue trace element profiles in populations of long-tailed duck breeding in the Canadian Arctic

Adult long-tailed ducks (Clangula hyemalis) were collected from nine locations across their breeding grounds in northern Canada and measurements of stable isotopes of carbon (delta(13)C), nitrogen (delta(15)N) and sulfur (delta(34)S) in bone collagen were used to investigate if relative use of freshwater habitats such as the Great Lakes (with expected depleted stable isotope profiles) compared with coastal marine environments (with expected enriched stable isotope foodweb profiles) could explain tissue trace element profiles. Contrary to expectation, all three stable isotopes did not covary in our sample, suggesting that mechanisms other than simple freshwater vs. marine isotopic gradients were involved among populations. All three stable isotopes varied significantly with collection location and both delta(15)N and delta(13)C values varied significantly between sexes suggesting that males exploit either a different food base or occur in different geographic areas than females for at least part of the year. The delta(34)S data, in particular, suggested that many of the birds breeding in the western Canadian Arctic probably overwinter in the Great Lakes along with many of the birds breeding in Hudson Bay. Males at the majority of collection locations had higher concentrations of hepatic Hg (1.1-8 microg/g dw), Cu (25-40 mug/g dw), Se (7.3-27 mug/g dw) and renal Cd (33-129 microg/g dw) than females. Concentrations of Hg, Cu and Cd were well below toxicological threshold levels found in the literature. However, hepatic Se concentrations in 64% of the females exceeded 10 mug/g dw and concentrations in 8% of the birds measured exceeded 33 microg/g dw suggesting levels of potential concern.     

Magnetic resonance imaging and quantitative analysis of particle deposition in porous media

Measurements of particle deposition and mobilization in water-saturated porous columns were performed using nuclear magnetic resonance imaging (MRI). The use of MRI enabled the acquisition of detailed, noninvasive measurements that quantify spatial and temporal evolution of particle transport patterns and porosity changes due to particle deposition. Measurements indicate that for the considered particle sizes and flow conditions significant particle deposition occurs at some distance into the column. Because identification of unique parametrizations for processes of particle straining, deposition, and detachment is complex and nonunique, a simple phenomenological model of particle deposition and porosity reduction is suggested. This model captures the essential features of the experimental measurements on spatial and temporal flow and deposition patterns.     

Characteristics of impala (Aepyceros melampus) skeletal muscles

The aim of this study was to determine citrate synthase (CS), phosphofructokinase (PFK) activities and myosin heavy chain (MHC) isoform contents in four muscle groups (semimembranosus (S), deltoideus (D), longissimus lumborum (LL), and psoas major (PM)) of impala (n=6). All four muscle groups expressed predominantly MHC IIa (means of 55±22-93±12%). MHC IIx was only expressed in D. In D, positive correlations were found between MHC I and age (r=0.93; P<0.05) and the weight of the animals (r=0.94; P<0.01). PFK (means of 175±179-374±181), CS (means of 100±23-126±38 μmol/min/gdw) and MHC content indicated that energy provision in the impala is produced to a large extent via oxidative pathways and fibre types vary with animal characteristics.     

Numerical stability of the classical and the modified Saul'yev's finite-difference methods

Stability criteria a modified Saul'yev's explicit method for parabolic partial differential equations are derived and compared with those of classical Saul'yev's explicit method and Crank-Nicholson's implicit method. The two Saul'yev methods operated in the averaging mode are found to be unconditionally stable with respect to the heat equation. However, when lower order terms are included in the linear test equation, the modified method is shown to have a greater stability region than the classical method, while the Crank-Nicholson method maintains its stability unconditionally. Results of numerical experiments confirm the validity of the derived criteria.