Distinct genotype and antigenicity among genogroup II sapoviruses

SaV, a pathogen of acute gastroenteritis, is divided into five genogroups, GI to GV. However, the relation between SaV antigenicity and genetic clusters is not fully understood. We have recently identified two GII SaV strains, Mc10 and C12, which are grouped into the same cluster based on the polymerase but are grouped into distinct clusters based on the capsid. To evaluate the difference in antigenicity between these two strains, VLP were expressed in mammalian cells. An antigen ELISA demonstrated for the first time that strains in the same GII SaV genogroup, but within different clusters, have distinct antigenicities.     

Cellular level observation of water loss and the refilling of tracheids in the xylem of Cryptomeria japonica during heartwood formation

The mechanism of heartwood formation in Cryptomeria japonica D. Don has long been studied since heartwood formation is a fundamental physiological feature of trees. In this study, the water distribution in the xylem of C. japonica was investigated at the cellular level to reveal the role of water distribution in the xylem during heartwood formation. Samples were taken from different heights of each trunk, in which the phases of heartwood formation differed. These were designated as SIH, which consisted of sapwood, intermediate wood, and heartwood; SI, which consisted of sapwood and intermediate wood but no heartwood; and S-all, which consisted entirely of sapwood. Cryo-scanning electron microscopic observations of the heartwood-formed (SIH) and non-heartwood-formed (SI and S-all) xylem revealed different patterns of water distribution changes in tracheids between the latewood and earlywood. In the latewood, almost all tracheids were filled with water in all areas from the sapwood to the heartwood (98–100% of tracheids had water in their lumina). In the earlywood, however, the water distribution differed between the sapwood (95–99%), intermediate wood (7–12%), and heartwood (4–100%). Many of the tracheids in the xylem, where the sapwood changed to intermediate wood lost water. In the heartwood, some tracheids remained empty, while others were refilled with water. These results suggest that the water distribution changes in individual tracheids are closely related to heartwood formation. Water loss from tracheids may be an important factor inducing heartwood formation in the xylem of C. japonica.     

Interaction between Intrinsically Disordered Proteins Frequently Occurs in a Human Protein-Protein Interaction Network

Intrinsic protein disorder is a widespread phenomenon characterised by a lack of stable three-dimensional structures and is considered to play an important role in protein-protein interactions (PPIs). This study examined the genome-wide preference of disorder in PPIs by using exhaustive disorder prediction in human PPIs. We categorised the PPIs into three types (interaction between disordered proteins, interaction between structured proteins, and interaction between a disordered protein and a structured protein) with regard to the flexibility of molecular recognition and compared these three interaction types in an existing human PPI network with those in a randomised network. Although the structured regions were expected to become the identifiers for binding recognition, this comparative analysis revealed unexpected results. The occurrence of interactions between disordered proteins was significantly frequent, and that between a disordered protein and a structured protein was significantly infrequent. We found that this propensity was much stronger in interactions between nonhub proteins. We also analysed the interaction types from a functional standpoint by using GO, which revealed that the interaction between disordered proteins frequently occurred in cellular processes, regulation, and metabolic processes. The number of interactions, especially in metabolic processes between disordered proteins, was 1.8 times as large as that in the randomised network. Another analysis conducted by using KEGG pathways provided results where several signaling pathways and disease-related pathways included many interactions between disordered proteins. All of these analyses suggest that human PPIs preferably occur between disordered proteins and that the flexibility of the interacting protein pairs may play an important role in human PPI networks.     

Contribution of spermatozoal centrosomes to the microtubule-organizing centre in Antarctic minke whale ( Balaenoptera bonaerensis )

Using an interspecies microinsemination assay with bovine oocytes, it was examined whether centrosomes of Antarctic minke whale spermatozoa function as the microtubule-organizing centre (MTOC). Bull and rat spermatozoa were used as positive and negative controls, respectively. Vitrified-warmed bovine mature oocytes were subjected to immunostaining against alpha-tubulin 4-6 h after intracytoplasmic injection (ICSI) of 5 mM dithiothreitol-treated spermatozoa. Aster formation occurred from whale spermatozoa (33%) and bull spermatozoa (33%), but very little from rat spermatozoa (3%). Activation treatment for the microinseminated oocytes with 7% ethanol + 2 mM 6-dimethylaminopurine resulted in a similar proportion of oocytes forming a whale sperm aster (35% vs 27% in the non-treated group; 4 h after ICSI) but a significantly larger aster (ratio of aster diameter to oocyte diameter, 0.57 vs 0.30 in the non-treated group). These results indicate that the centrosome introduced into bovine oocytes by whale spermatozoa contributes to the MTOC and that assembly of the microtubule network is promoted by oocyte activation.     

Irbesartan attenuates ischemic brain damage by inhibition of MCP-1/CCR2 signaling pathway beyond AT1 receptor blockade

Angiotensin II type 1 (AT₁) receptor blockers (ARBs) are known to prevent the onset of stroke and to attenuate neural damage. Additional beneficial effects of ARBs, independent of AT₁ receptor blockade, have been highlighted. Irbesartan is reported to act as an antagonist of the monocyte chemoattractant protein-1 (MCP-1) receptor, C–C chemokine receptor 2 (CCR2), due to its molecular structure. We examined the possible synergistic effects of co-administration of irbesartan with propagermanium, a CCR2 antagonist, on ischemic brain damage. Administration of propagermanium decreased ischemic brain area after middle cerebral artery occlusion (MCAO). To study the possible synergistic effects of propagermanium with ARBs, we employed non-effective lower doses of irbesartan and losartan. Administration of irbesartan with propagermanium decreased the ischemic brain area more markedly compared with propagermanium alone, but co-administration of losartan did not. MCP-1 mRNA level was significantly increased on the ipsilateral side after MCAO, and administration of irbesartan with propagermanium decreased the MCP-1 level, whereas co-administration of losartan did not. Similar results were obtained for MCP-1 protein level. CCR2 mRNA expression was significantly elevated on the ipsilateral side; however, no significant difference was observed between each group. mRNA levels of other inflammatory cytokines such as TNF-α and IL-1β also significantly increased on the ipsilateral side, but the expression levels were not changed by each drug treatment. Taking these findings together, irbesartan exerts more beneficial effects on ischemic brain damage with an MCP-1 receptor blocker, at least due to its inhibitory effects on MCP-1/CCR2 signaling beyond AT₁ receptor blockade.     

Heterologous expression and characterization of processing ��-glucosidase I from Aspergillus brasiliensis ATCC 9642

A gene for processing α-glucosidase I from a filamentous fungus, Aspergillus brasiliensis (formerly called Aspergillus niger) ATCC 9642 was cloned and fused to a glutathione S-transferase tag. The active construct with the highest production level was a truncation mutant deleting the first 16 residues of the hydrophobic N-terminal domain. This fusion enzyme hydrolyzed pyridylaminated (PA-) oligosaccharides Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA and the products were identified as Glc(2)Man(9)GlcNAc(2)-PA and Glc(2)Man(4)-PA, respectively. Saturation curves were obtained for both Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA, and the K (m) values for both substrates were estimated in the micromolar range. When 1 μM Glc(3)Man(4)-PA was used as a substrate, the inhibitors kojibiose and 1-deoxynojirimycin had similar effects on the enzyme; at 20 μM concentration, both inhibitors reduced activity by 50%.