Scale-dependent effects of windthrow disturbance on forest arthropod communities

The effect of disturbance on local communities may operate within the context of the spatial landscape. We examined the scale-dependent effects of windthrow disturbance caused by a large typhoon on three arthropod communities in a temperate forest of Japan. Canopy arthropods were collected by beating foliage, forest-floor arthropods were collected by sweeping the vegetation, and flying arthropods were collected in Malaise traps. To assess the “functional spatial scale” at which arthropods responded to tree-fall disturbance, the gap rate was quantified at different spatial scales by sequentially enlarging the radius of a circular landscape sector in 10-m increments from 10 to 500 m. We then analyzed the responses of order richness and abundance to the gap rate for each arthropod community. The spatial scale of the significant best-fitting model, which was selected from the models fitted to the gap rate at stepwise spatial scales, was regarded as the arthropod-specific functional spatial scale. Arthropod order richness was not dependent on the gap rate. In contrast, arthropod order abundance depended significantly on the gap rate in many orders, but varied in the response direction and functional spatial scale. These order-specific, scale-dependent responses to tree-fall gaps could complicate interactions among organisms, leading to complex community organization. An understanding of the spatial processes that link the use of space by organisms with the spatial scale at which ecological processes are experienced is required to elucidate the responses of populations, communities, and biotic interactions to disturbances in a spatial landscape context.     

In vitro growth and development of bovine oocyte-granulosa cell complexes on the flat substratum: effects of high polyvinylpyrrolidone concentration in culture medium

The aim of this study was to establish a culture system to support the growth of bovine oocytes as enclosed in granulosa cell complexes that extend on a flat substratum. Such systems have been established for mouse oocytes but are not applicable to larger animals because it is difficult to maintain an appropriate association between the oocyte and companion somatic cells. Growing bovine oocytes with a mean diameter of 95 microm were isolated from early antral follicles: the growing stage corresponds to that of oocytes in preantral follicles of 12-day-old mice. Oocyte-granulosa cell complexes were cultured for 14 days in modified TCM199 medium supplemented with 5% fetal bovine serum, 4 mM hypoxanthine, and 0.1 microg/ml estradiol. The novel modification made for this medium was a high concentration, 4% (w/v), of polyvinylpyrrolidone (PVP; molecular weight of 360000). The flat substratum used was either an insert membrane fit in the culture plate or the bottom surface of the wells of 96-well culture plates. PVP influenced the organization of complexes, resulting in a firm association between the oocyte and the innermost layer of surrounding cells. More oocytes enclosed by a complete cell layer were recovered from the medium supplemented with 4% PVP than from the control medium. Similarly, of the oocytes initially introduced into the growth culture, a significantly larger proportion developed to the blastocyst stage from medium containing 4% PVP than from medium without PVP. When PVP medium was used, the overall yield of blastocysts was similar between the system with the insert membranes (12%) and that with the 96-well culture plates (9%). A calf was produced from one of four embryos derived from oocytes grown in 96-well culture plates, matured, and fertilized in vitro and then transferred to a recipient cow.     

Fbs1 protects the malfolded glycoproteins from the attack of peptide:N-glycanase

Fbs1 is a cytosolic lectin putatively operating as a chaperone as well as a substrate-recognition subunit of the SCF(Fbs1) ubiquitin ligase complex. To provide structural and functional basis of preferential binding of Fbs1 to unfolded glycoproteins, we herein characterize the interaction of Fbs1 with a heptapeptide carrying Man3GlcNAc2 by nuclear magnetic resonance (NMR) spectroscopy and other biochemical methods. Inspection of the NMR data obtained by use of the isotopically labeled glycopeptide indicated that Fbs1 interacts with sugar-peptide junctions, which are shielded in native glycoprotein, in many cases, but become accessible to Fbs1 in unfolded glycoproteins. Furthermore, Fbs1 was shown to inhibit deglycosylation of denatured ribonuclease B by a cytosolic peptide:N-glycanase (PNGase). On the basis of these data, we suggest that Fbs1 captures malfolded glycoproteins, protecting them from the attack of PNGase, during the chaperoning or ubiquitinating operation in the cytosol.     

Environmental analysis of packaging‐derived changes in food production and consumer behavior

This study analyzed the environmental impacts of packaging‐derived changes in food production and consumer behavior to assist packaging designers in making environmentally conscious decisions. Packaging can be functionalized to prevent food loss and waste (FLW), for example, extending the expiration date and apportioning the package size, but it can generate additional environmental impacts from changes in food and packaging production. Previous studies assessed additional impacts from packaging production; however, the effects of packaging functionalization are yet to be connected with food production and consumer behavior. To examine the effect of functionalization on these aspects, we analyzed packaging‐derived changes in food production for milk and cabbage products. The case study compared products with functionalized packaging that permits a longer expiration date or a smaller portion size to their base‐case products. Our results showed that the packaging‐derived changes increased the global warming potential (GWP) of food production more than other processes did. Thus, changes in food production weakened the effectiveness of the packaging functionalization to decrease the GWP. Moreover, the analysis of consumer behavior scenarios showed that consumers’ perception of the expiration date decisively influences the effectiveness of packaging functionalization. When consumers discarded food after the expiration date, provided they consumed in small quantities, the packaging functionalization reduced FLW. From the scenario analysis, we identified appropriate combinations of packaging functionalization and consumer behaviors to effectively decrease total GWP. With our expanded analysis, packaging designers can understand the effectiveness of their decisions on the product life cycle in reducing FLW and environmental impacts.     

Site-specific incorporation of an unnatural amino acid into proteins in mammalian cells

A suppressor tRNA(Tyr) and mutant tyrosyl-tRNA synthetase (TyrRS) pair was developed to incorporate 3-iodo-L-tyrosine into proteins in mammalian cells. First, the Escherichia coli suppressor tRNA(Tyr) gene was mutated, at three positions in the D arm, to generate the internal promoter for expression. However, this tRNA, together with the cognate TyrRS, failed to exhibit suppressor activity in mammalian cells. Then, we found that amber suppression can occur with the heterologous pair of E.coli TyrRS and Bacillus stearothermophilus suppressor tRNA(Tyr), which naturally contains the promoter sequence. Furthermore, the efficiency of this suppression was significantly improved when the suppressor tRNA was expressed from a gene cluster, in which the tRNA gene was tandemly repeated nine times in the same direction. For incorporation of 3-iodo-L-tyrosine, its specific E.coli TyrRS variant, TyrRS(V37C195), which we recently created, was expressed in mammalian cells, together with the B.stearothermophilus suppressor tRNA(Tyr), while 3-iodo-L-tyrosine was supplied in the growth medium. 3-Iodo-L-tyrosine was thus incorporated into the proteins at amber positions, with an occupancy of >95%. Finally, we demonstrated conditional 3-iodo-L-tyrosine incorporation, regulated by inducible expression of the TyrRS(V37C195) gene from a tetracycline-regulated promoter.     

Tea catechins reduce inflammatory reactions via mitogen-activated protein kinase pathways in toll-like receptor 2 ligand-stimulated dental pulp cells

AimsIn this study, we evaluated whether catechins could inhibit the expression of pro-inflammatory mediators induced by dental caries-related bacteria, Streptococci, or pathogen-associated molecular patterns (PAMPs) stimulation in human dental pulp fibroblasts (HDPF). We further determined the mechanisms of the anti-inflammatory activity of catechins.Main methodsStreptococci or PAMP-stimulated HDPF were treated with catechin, and then the expression and production of pro-inflammatory mediators were determined by RT-PCR and ELISA. Furthermore, the signal transduction pathways activated with toll-like receptor (TLR)2 ligand were assessed by Immunoblot and ELISA using blocking assay with specific inhibitors.Key findingsIncreased expressions of pro-inflammatory mediators are found in inflamed dental pulp, especially in HDPF. We recently reported that dental pulpal innate immune responses may mainly result from the predominantly-expressed TLR2 signaling. Catechins, polyphenolic compounds in green tea, exert protective and healing effects through multiple mechanisms, including antioxidative and anti-inflammatory effects. However, there are no reports concerning the effects of catechins on dental pulp. In this study, we demonstrated that the up-regulated expressions of IL-8 or PGE₂ in Streptococci or PAMP-stimulated HDPF were inhibited by catechins, (?)-epicatechin gallate (ECG) and (?)-epigallocatechin gallate (EGCG). In TLR2 ligand-stimulated HDPF, specific inhibitors of extracellular signal regulated kinase (ERK)1/2, p38, c-jun NH₂-terminal kinase (SAP/JNK), NF-κB or catechins markedly reduced the level of pro-inflammatory mediators and the phosphorylation of these signal transduction molecules was suppressed by catechins.SignificanceThese findings suggest that catechins might be useful therapeutically as an anti-inflammatory modulator of dental pulpal inflammation.