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Base Composition (base + composition)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Resolution of phylogenetic relationships of the major subfamilies of the Delphacidae (Homoptera: Fulgoroidea) using the mitochondrial ribosomal DNA

INSECT SCIENCE, Issue 3 2006
EDDY DIJKSTRA
Abstract Delphacid relationships from the genus level to the subfamily have been completely resolved (among those taxa examined) using sequence data from the 3'end of the 12S gene. Monophyly of the non-asiracine subfamilies was strongly supported and the asiracine Ugyops was placed in the most basal position of the tree. Support levels for monophyly of the Delphacini increased after weighting transversions more heavily than transitions and after removing the cixiid outgroup from the dataset. Among the Delphacini, Conomelus and Megamelus were more closely related to each other than either was to Chloriona. These results are in agreement with the tree based on morphological characters. However, in contrast to morphological data our results strongly supported a sister group relationship between the Stenocraninae and the Kelisiinae. Although the 12S gene fragment gave some information about the species relationships within Chloriona, neither this fragment nor the 5'end of the 16S gene appear to be very useful for this level. Molecular evolutionary patterns provided evidence that there has been a shift in base composition from T to A during the early evolution of the non-Asiracinae. The non-Asiracinae also had comparatively fast substitution rates and these two observations are possibly correlated. In the ,modern' delphacid Chloriona, the AT content was comparatively low in regions free of constraints but this was not the case for ,non-modern' delphacids. The tRNA for valine has been translocated elsewhere, probably before the Delphacidae and Cixiidae diverged from each other. [source]

Micelle-to-vesicle transition induced by oligonucleotide in SDS/DEAB mixed system with a net negative charge

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2008
Xia Guo
Abstract Sodium dodecyl sulfate (SDS)/dodecyl triethyl ammonium bromide (DEAB) mixed micelles (with SDS in excess) can transform to vesicles only when the temperature is higher than a critical value. In this study, we report for the first time that oligonucleotide can decrease the critical temperature to a much lower value and, hence, induce micelle-to-vesicle transition. The facilitation efficiency of oligonucleotide on vesicle formation is closely dependent on its size and base composition. Moreover, the SDS/DEAB/oligonucleotide vesicles are negatively charged and the hydrophobic interaction between oligonucleotide and SDS/DEAB mixed micelles is the driving force. As, so far, the report about the facilitation effect of oligonucleotide and DNA on vesicle formation is very limited, this study may provide some helpful information for the application of DNA/amphiphile system. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7491,7504, 2008 [source]

Label-Free Colorimetric Screening of Nuclease Activity and Substrates by Using Unmodified Gold Nanoparticles

CHEMBIOCHEM, Issue 12 2009
Xinhui Lou Dr.
Don't get the blues: The dNMPs produced by nucleases can better stabilize unmodified AuNPs than ss- or dsDNA with same base composition, thus the AuNPs remain red in contrast to the blue-purple change observed in the absence of nucleases or substrates. This color change can be used to monitor the activity of the enzyme and allows for label-free substrate screening. [source]

Mitochondrial genomes of the sheep blowfly, Lucilia sericata, and the secondary blowfly, Chrysomya megacephala

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2008
J. R. STEVENS
Abstract This paper presents complete mitochondrial genomes for the sheep blowfly, Lucilia sericata (Meigen), and the secondary blowfly, Chrysomya megacephala (Fabricius). Both L. sericata and C. megacephala had standard dipteran-type mitochondrial genome architectures and lengths of 15 945 bp and 15 831 bp, respectively. Additionally, C. megacephala possessed a tRNA duplication either side of the D-loop, as previously reported in another Chrysomya species, C. putoria; this duplication appears to be synapomorphic for the genus Chrysomya. As in other insect mitochondrial genomes, base compositions had a high AT content, with both genomes more than 76% AT-rich. [source]