Sequence-level analysis of the diploidization process in the triplicated FLOWERING LOCUS C region of Brassica rapa

Strong evidence exists for polyploidy having occurred during the evolution of the tribe Brassiceae. We show evidence for the dynamic and ongoing diploidization process by comparative analysis of the sequences of four paralogous Brassica rapa BAC clones and the homologous 124-kb segment of Arabidopsis thaliana chromosome 5. We estimated the times since divergence of the paralogous and homologous lineages. The three paralogous subgenomes of B. rapa triplicated 13 to 17 million years ago (MYA), very soon after the Arabidopsis and Brassica divergence occurred at 17 to 18 MYA. In addition, a pair of BACs represents a more recent segmental duplication, which occurred approximately 0.8 MYA, and provides an exception to the general expectation of three paralogous segments within the B. rapa genome. The Brassica genome segments show extensive interspersed gene loss relative to the inferred structure of the ancestral genome, whereas the Arabidopsis genome segment appears little changed. Representatives of all 32 genes in the Arabidopsis genome segment are represented in Brassica, but the hexaploid complement of 96 has been reduced to 54 in the three subgenomes, with compression of the genomic region lengths they occupy to between 52 and 110 kb. The gene content of the recently duplicated B. rapa genome segments is identical, but intergenic sequences differ.     

The effects of long-term endurance training on the immune and endocrine systems of elderly men: the role of cytokines and anabolic hormones

Background  

a decline in immune and endocrine function occurs with aging. The main purpose of this study was to investigate the impact of long-term endurance training on the immune and endocrine system of elderly men. The possible interaction between these systems was also analysed.     

κ-Casein-Based Hierarchical Suprastructures and Their Use for Selective Temporal and Spatial Control over Neuronal Differentiation

Functions are diversified by producing hierarchical structures from a single raw material. Biologically compatible milk protein of κ-casein has been employed to fabricate higher-order suprastructures. In the presence of dithiothreitol and heat treatment, κ-casein transforms into amyloid fibrils with distinctive morphology attributable to mechanism-based fibrillar polymorphism. As the fibrils elongate to yield high aspect ratio during high-temperature incubation, the resulting fibrils laterally associate into the liquid crystalline state by forming a two-dimensional fibrillar array. Following a desalting process, the fibrillar arrays turn into a three-dimensional matrix of hydrogel that could be selectively disintegrated by subsequent salt treatment. The hydrogel was demonstrated to be a matrix capable of exhibiting controlled release of bioactive substances like retinoic acid, which led to temporal and spatial control over the differentiation of neuronal cells. Therefore, the hierarchical suprastructure formation derived from the single protein of κ-casein producing one-dimensional protein nanofibrils, a two-dimensional liquid crystalline state and a three-dimensional hydrogel could be widely appreciated in various areas of nanobiotechnology including drug delivery and tissue engineering.     

Instantaneous amyloid fibril formation of alpha-synuclein from the oligomeric granular structures in the presence of hexane

Amyloid fibrils found in various neurodegenerative disorders are also recognized as high-performance protein nanomaterials with a formidable rigidity. Elucidation of an underlying molecular mechanism of the amyloid fibril formation is crucial not only to develop controlling strategy toward the diseases, but also to apply the protein fibrils for future nanobiotechnology. alpha-Synuclein is an amyloidogenic protein responsible for the radiating filament formation within Lewy bodies of Parkinson's disease. The amyloid fibril formation of alpha-synuclein has been shown to be induced from the oligomeric granular species of the protein acting as a growing unit by experiencing structural rearrangement within the preformed oligomeric structures in the presence of an organic solvent of hexane. This granule-based concerted amyloid fibril formation model would parallel the prevalent notion of nucleation-dependent fibrillation mechanism in the area of amyloidosis.     

The effect of histidine residue modification on tyrosinase activity and conformation: inhibition kinetics and computational prediction

We found that the histidine chemical modification of tyrosinase conspicuously inactivated enzyme activity. The substrate reactions with diethylpyridinecarbamate showed slow-binding inhibition kinetics (K(I) = 0.24 +/- 0.03 mM). Bromoacetate, as another histidine modifier, was also applied in order to study inhibition kinetics. The bromoacetate directly induced the exposures of hydrophobic surfaces following by complete inactivation via ligand binding. For further insights, we predicted the 3D structure of tyrosinase and simulated the docking between tyrosinase and diethylpyridinecarbamate. The docking simulation was shown to the significant binding energy scores (-3.77 kcal/mol by AutoDock4 and -25.26 kcal/mol by Dock6). The computational prediction was informative to elucidate the role of free histidine residues at the active site, which are related to substrate accessibility during tyrosinase catalysis.     

Influenza H5N1 virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells

Background

Highly pathogenic avian influenza (HPAI) H5N1 virus is entrenched in poultry in Asia and Africa and continues to infect humans zoonotically causing acute respiratory disease syndrome and death. There is evidence that the virus may sometimes spread beyond respiratory tract to cause disseminated infection. The primary target cell for HPAI H5N1 virus in human lung is the alveolar epithelial cell. Alveolar epithelium and its adjacent lung microvascular endothelium form host barriers to the initiation of infection and dissemination of influenza H5N1 infection in humans. These are polarized cells and the polarity of influenza virus entry and egress as well as the secretion of cytokines and chemokines from the virus infected cells are likely to be central to the pathogenesis of human H5N1 disease.

Aim

To study influenza A (H5N1) virus replication and host innate immune responses in polarized primary human alveolar epithelial cells and lung microvascular endothelial cells and its relevance to the pathogenesis of human H5N1 disease.

Methods

We use an in vitro model of polarized primary human alveolar epithelial cells and lung microvascular endothelial cells grown in transwell culture inserts to compare infection with influenza A subtype H1N1 and H5N1 viruses via the apical or basolateral surfaces.

Results

We demonstrate that both influenza H1N1 and H5N1 viruses efficiently infect alveolar epithelial cells from both apical and basolateral surface of the epithelium but release of newly formed virus is mainly from the apical side of the epithelium. In contrast, influenza H5N1 virus, but not H1N1 virus, efficiently infected polarized microvascular endothelial cells from both apical and basolateral aspects. This provides a mechanistic explanation for how H5N1 virus may infect the lung from systemic circulation. Epidemiological evidence has implicated ingestion of virus-contaminated foods as the source of infection in some instances and our data suggests that viremia, secondary to, for example, gastro-intestinal infection, can potentially lead to infection of the lung. HPAI H5N1 virus was a more potent inducer of cytokines (e.g. IP-10, RANTES, IL-6) in comparison to H1N1 virus in alveolar epithelial cells, and these virus-induced chemokines were secreted onto both the apical and basolateral aspects of the polarized alveolar epithelium.

Conclusion

The predilection of viruses for different routes of entry and egress from the infected cell is important in understanding the pathogenesis of influenza H5N1 infection and may help unravel the pathogenesis of human H5N1 disease.