Using a continuous chain length distribution, the effect of polydispersity on the structures
of vesicles self-assembled by amphiphilic polydisperse diblock copolymers in dilute solutions is investigated
by two-dimensional (2D) real-space self-consistent-field theory. It is discovered that larger polydispersity
favors the formation of smaller vesicles or quasi-vesicles. This polydispersity effect can be attributed to
the segregation of copolymers according to their chain lengths. Two types of chain segregations are
observed. First of all, the shorter chains tend to localize at the A/B interfaces while the longer chains
tend to stretch to the outer surfaces. Second, there is a separation of copolymers to the inner and outer
monolayers of the bilayers, leading to a longer average chain length in outer monolayer.
We utilize the wormlike chain model in the framework of the self-consistent field theory to investigate the influence of chain rigidity on the phase diagram of AB diblock copolymers in the full three-dimensional space. We develop an efficient numerical scheme that can be used to calculate the physical properties of ordered microstructures self-assembled from semiflexible block copolymers. The calculation describes the entire physical picture of the phase diagram, crossing from the flexible over to rodlike polymer behavior.
We describe, for the first time, the generation of a viral DNA chip for simultaneous expression measurements of nearly all known open reading frames (ORFs) in the largest member of the herpesvirus family, human cytomegalovirus (HCMV). In this study, an HCMV chip was fabricated and used to characterize the temporal class of viral gene expression. The viral chip is composed of microarrays of viral DNA prepared by robotic deposition of oligonucleotides on glass for ORFs in the HCMV genome. Viral gene expression was monitored by hybridization to the oligonucleotide microarrays with fluorescently labelled cDNAs prepared from mock-infected or infected human foreskin fibroblast cells. By using cycloheximide and ganciclovir to block de novo viral protein synthesis and viral DNA replication, respectively, the kinetic classes of array elements were classified. The expression profiles of known ORFs and many previously uncharacterized ORFs provided a temporal map of immediate-early (α), early (β), early-late (γ1), and late (γ2) genes in the entire genome of HCMV. Sequence compositional analysis of the 5′ noncoding DNA sequences of the temporal classes, performed by using algorithms that automatically search for defined and recurring motifs in unaligned sequences, indicated the presence of potential regulatory motifs for β, γ1, and γ2 genes. In summary, these fabricated microarrays of viral DNA allow rapid and parallel analysis of gene expression at the whole viral genome level. The viral chip approach coupled with global biochemical and genetic strategies should greatly speed the functional analysis of established as well as newly discovered large viral genomes.
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