Diversity and ubiquity of xylariaceous endophytes in live and dead leaves of temperate forest trees

To test the hypothesis that xylariaceous endophytes were ubiquitous on live and dead leaves of various tree species in the field, xylariaceous fungi were isolated from live leaves and bleached and nonbleached portions of dead leaves of a total of 94 tree species in a cool temperate forest in Japan. The biodiversity of xylariaceous endophytes was evaluated as the richness of operational taxonomic units (OTUs) determined by phylogenetic analysis of the nucleotide sequence of the D1/D2 region of the LSU rDNA of fungal isolates. A total of 326 isolates of xylariaceous fungi were isolated from live and dead leaves and classified into 15 OTUs. The three major OTUs, Xylaria sp.1, Nemania sp., and Biscogniauxia sp., accounted for 94% (308 isolates) of the total number of isolates, and were isolated from various live and dead leaves. Xylaria sp.1 was frequently encountered on bleached portions (which were produced due to the selective decomposition of lignin) of dead leaves of broad-leaved deciduous tree species. The results suggest that xylariaceous endophytes did not show host specificity and had a saprobic phase on dead leaves in their life cycles and that Xylaria sp.1 was capable of decomposing lignin in the field conditions.     

Age-dependent changes in the functions and compositions of photosynthetic complexes in the thylakoid membranes of Arabidopsis thaliana

Photosynthetic complexes in the thylakoid membrane of plant leaves primarily function as energy-harvesting machinery during the growth period. However, leaves undergo developmental and functional transitions along aging and, at the senescence stage, these complexes become major sources for nutrients to be remobilized to other organs such as developing seeds. Here, we investigated age-dependent changes in the functions and compositions of photosynthetic complexes during natural leaf senescence in Arabidopsis thaliana. We found that Chl a/b ratios decreased during the natural leaf senescence along with decrease of the total chlorophyll content. The photosynthetic parameters measured by the chlorophyll fluorescence, photochemical efficiency (F _v/F _m) of photosystem II, non-photochemical quenching, and the electron transfer rate, showed a differential decline in the senescing part of the leaves. The CO₂ assimilation rate and the activity of PSI activity measured from whole senescing leaves remained relatively intact until 28 days of leaf age but declined sharply thereafter. Examination of the behaviors of the individual components in the photosynthetic complex showed that the components on the whole are decreased, but again showed differential decline during leaf senescence. Notably, D1, a PSII reaction center protein, was almost not present but PsaA/B, a PSI reaction center protein is still remained at the senescence stage. Taken together, our results indicate that the compositions and structures of the photosynthetic complexes are differentially utilized at different stages of leaf, but the most dramatic change was observed at the senescence stage, possibly to comply with the physiological states of the senescence process.     

Conformational change of a unique sequence in a fungal galectin from Agrocybe cylindracea controls glycan ligand-binding specificity

A fungal galectin from Agrocybe cylindracea (ACG) exhibits broad binding specificity for β-galactose–containing glycans. We determined the crystal structures of wild-type ACG and the N46A mutant, with and without glycan ligands. From these structures and a saccharide-binding analysis of the N46A mutant, we revealed that a conformational change of a unique insertion sequence containing Asn46 provides two binding modes for ACG, and thereby confers broad binding specificity. We propose that the unique sequence provides these two distinct glycan-binding modes by an induced-fit mechanism.     

Exercise-induced enhancement of insulin sensitivity is associated with accumulation of M2-polarized macrophages in mouse skeletal muscle

Exercise enhances insulin sensitivity in skeletal muscle, but the underlying mechanism remains obscure. Recent data suggest that alternatively activated M2 macrophages enhance insulin sensitivity in insulin target organs such as adipose tissue and liver. Therefore, the aim of this study was to determine the role of anti-inflammatory M2 macrophages in exercise-induced enhancement of insulin sensitivity in skeletal muscle. C57BL6J mice underwent a single bout of treadmill running (20 m/min, 90 min). Twenty-four hours later, ex vivo insulin-stimulated 2-deoxy glucose uptake was found to be increased in plantaris muscle. This change was associated with increased number of CD163-expressing macrophages (i.e. M2-polarized macrophages) in skeletal muscle. Systemic depletion of macrophages by pretreatment of mice with clodronate-containing liposome abrogated both CD163-positive macrophage accumulation in skeletal muscle as well as the enhancement of insulin sensitivity after exercise, without affecting insulin-induced phosphorylation of Akt and AS160 or exercise-induced GLUT4 expression. These results suggest that accumulation of M2-polarized macrophages is involved in exercise-induced enhancement of insulin sensitivity in mouse skeletal muscle, independently of the phosphorylation of Akt and AS160 and expression of GLUT4.     

Replication Study in a Japanese Population of Six Susceptibility Loci for Type 2 Diabetes Originally Identified by a Transethnic Meta-Analysis of Genome-Wide Association Studies

AimWe performed a replication study in a Japanese population to evaluate the association between type 2 diabetes and six susceptibility loci (TMEM154, SSR1, FAF1, POU5F1, ARL15, and MPHOSPH9) originally identified by a transethnic meta-analysis of genome-wide association studies (GWAS) in 2014.MethodsWe genotyped 7,620 Japanese participants (5,817 type 2 diabetes patients and 1,803 controls) for each of the single nucleotide polymorphisms (SNPs) using a multiplex polymerase chain reaction invader assay. The association of each SNP locus with the disease was evaluated using logistic regression analysis.ResultsOf the six SNPs examined in this study, four (rs6813195 near TMEM154, rs17106184 in FAF1, rs3130501 in POU5F1 and rs4275659 near MPHOSPH9) had the same direction of effect as in the original reports, but two (rs9505118 in SSR1 and rs702634 in ARL15) had the opposite direction of effect. Among these loci, rs3130501 and rs4275659 were nominally associated with type 2 diabetes (rs3130501; p = 0.017, odds ratio [OR] = 1.113, 95% confidence interval [CI] 1.019–1.215, rs4275659; p = 0.012, OR = 1.127, 95% CI 1.026–1.238, adjusted for sex, age and body mass index), but we did not observe a significant association with type 2 diabetes for any of the six evaluated SNP loci in our Japanese population.ConclusionsOur results indicate that effects of the six SNP loci identified in the transethnic GWAS meta-analysis are not major among the Japanese, although SNPs in POU5F1 and MPHOSPH9 loci may have some effect on susceptibility to type 2 diabetes in this population.     

Role of IGFBP7 in Diabetic Nephropathy: TGF-β1 Induces IGFBP7 via Smad2/4 in Human Renal Proximal Tubular Epithelial Cells

Tubular injury is one of the important determinants of progressive renal failure in diabetic nephropathy (DN), and TGF-β1 has been implicated in the pathogenesis of tubulointerstitial disease that characterizes proteinuric renal disease. The aim of this study was to identify novel therapeutic target molecules that play a role in the tubule damage of DN. We used an LC-MS/MS-based proteomic technique and human renal proximal epithelial cells (HRPTECs). Urine samples from Japanese patients with type 2 diabetes (n = 46) were used to quantify the candidate protein. Several proteins in HRPTECs in cultured media were observed to be driven by TGF-β1, one of which was 33-kDa IGFBP7, which is a member of IGFBP family. TGF-β1 up-regulated the expressions of IGFBP7 mRNA and protein in a dose- and time-dependent fashion via Smad2 and 4, but not MAPK pathways in HRPTECs. In addition, the knockdown of IGFBP7 restored the TGF-β1-induced epithelial to mesenchymal transition (EMT). In the immunohistochemical analysis, IGFBP7 was localized to the cytoplasm of tubular cells but not that of glomerular cells in diabetic kidney. Urinary IGFBP7 levels were significantly higher in the patients with macroalbuminuria and were correlated with age (r = 0.308, p = 0.037), eGFR (r = −0.376, p = 0.01), urinary β₂-microglobulin (r = 0.385, p = 0.008), and urinary N-acetyl-beta-D-glucosaminidase (NAG) (r = 0.502, p = 0.000). A multivariate regression analysis identified urinary NAG and age as determinants associated with urinary IGFBP7 levels. In conclusion, our data suggest that TGF-β1 enhances IGFBP7 via Smad2/4 pathways, and that IGFBP7 might be involved in the TGF-β1-induced tubular injury in DN.     

EcoBalance 2018—Nexus of ideas: innovation by linking through life cycle thinking (9–12 October 2018, Tokyo,Japan)

The International Journal of Life Cycle Assessment -     

Phase resetting curves and oscillatory stability in interneurons of rat somatosensory cortex

Synchronous oscillations in neural activity are found over wide areas of the cortex. Specific populations of interneurons are believed to play a significant role in generating these synchronized oscillations through mutual synaptic and gap-junctional interactions. Little is known, though, about the mechanism of how oscillations are maintained stably by particular types of interneurons and by their local networks. To obtain more insight into this, we measured membrane-potential responses to small current-pulse perturbations during regular firing, to construct phase resetting curves (PRCs) for three types of interneurons: nonpyramidal regular-spiking (NPRS), low-threshold spiking (LTS), and fast-spiking (FS) cells. Within each cell type, both monophasic and biphasic PRCs were observed, but the proportions and sensitivities to perturbation amplitude were clearly correlated to cell type. We then analyzed the experimentally measured PRCs to predict oscillation stability, or firing reliability, of cells for a complex stochastic input, as occurs in vivo. To do this, we used a method from random dynamical system theory to estimate Lyapunov exponents of the simplified phase model on the circle. The results indicated that LTS and NPRS cells have greater oscillatory stability (are more reliably entrained) in small noisy inputs than FS cells, which is consistent with their distinct types of threshold dynamics.     

Meiotic stage-dependent induction of chromosome aberrations in Chinese hamster primary oocytes exposed to topoisomerase II inhibitor etoposide

To investigate the chromosomal effects of topoisomerase II (topo-II)-interactive drugs on mammalian primary oocytes, female Chinese hamsters were treated with etoposide (VP-16) at various intervals pre- and post-human chorionic gonadotropin (hCG) injections. Chromosome analysis of oocytes at metaphase II (M II) showed that treatment with VP-16 at 50h pre-hCG had no effect, but the treatments between 24h pre-hCG and 2h post-hCG often caused structural chromosome aberrations. Although treatment at 4h post-hCG had no effect, subsequent treatments at 6 and 8h post-hCG produced a significant increase in structural chromosome aberrations. No effect was found following treatment at 10h post-hCG. The incidence of aneuploidy following exposure to VP-16 was also dependent on the time of hCG injection. Taking the time course of meiotic progression in primary oocytes following hCG injection and pharmacokinetics of VP-16 into consideration, it is likely that meiotic stages from late dictyate to diakinesis are highly sensitive to VP-16, while stages at dictyate and from metaphase I (M I) to telophase I (telo I) are relatively insensitive to the drug. Moreover, the effect of VP-16 on structural chromosome aberrations and aneuploidy was dose-dependent.Chromosome analysis at M I detected a frequent occurrence of structural chromosome aberrations in treated oocytes. This suggests that structural aberrations may be caused by disruption of cleavable complexes during chromosome condensation. Detection of chromosome bridges during anaphase I/telophase I (ana I/telo I) may support the hypothesis that induction of aneuploidy by VP-16 is due to failure in decatenation of recombinant homologous chromosomes.