RADIATION EFFECTS ON CELL POPULATIONS IN THE INTESTINAL EPITHELIUM OF MICE AND ITS THEORY

Mice were exposed to 1000 R of X-rays to their trunks and sacrificed every day up to the tenth day after exposure. Cell counts were made on histological sections of the duodenum. The cell counts in the crypts were reduced to about 50% of the control value on the first day after exposure. The cell counts began to recover on the third day and an overshoot of 170% was observed on the fourth day; thereafter the crypt cell counts tended to return to the control level. The cell counts on the villi reached their minimum value on the third day after exposure. Following an overshoot on the sixth day, the villus cell counts returned to the control level by the tenth day. The above experimental results were analysed using a two-compartment model with a feedback term. A logistic proliferation was assumed for the proliferative crypt cells, while for the postmitotic villus cells the compartment was assumed to be a first in-first out type. The calculated results with this model are in general consistent with the experimental ones. The model seems to possess some essential features of the dynamics of cell renewal in the intestinal mucosa.     

Burr marigold (Bidens tripartita L.) roots directly and immediately scavenge rhizosphere methane with highly exuded hydrogen peroxide via a rhizosphere Fenton reaction

Plant and Soil - The major factors controlling the soil methane (CH4) concentration and CH4 emissions of various plant (mainly wetland) species were identified. Five plant species (Oryza sativa,...     

Soil carbon dynamics and aquatic metabolism of a wet–dry tropics wetland system

Freshwater wetlands are a key component of the global carbon cycle. Wet–dry tropics wetlands function as wet-season carbon sinks and dry-season carbon sources with low aquatic metabolism controlled by predictably seasonal, yet magnitude-variable flow regimes and inundation patterns. However, these dynamics have not been adequately quantified in Australia’s relatively unmodified wet–dry tropics freshwater wetlands. A baseline understanding is required before analysis of land-use or climate change impacts on these aquatic ecosystems can occur. This study characterises geomorphology and sedimentology within a seasonally connected wet–dry tropics freshwater wetland system at Kings Plains, Queensland, Australia, and quantifies soil carbon stocks and wet- and dry-season aquatic metabolism. Soil carbon stocks derived from loss-on-ignition on samples to 1 m depth were 51.5?±?7.8 kg C m^?2, higher than other wet–dry tropics wetlands globally, with potential for long-term retention at greater depths. Gross primary productivity of phytoplankton (GPP) and planktonic respiration (PR) measured through biological oxygen demand bottle experiments in the water column of sediment inundated under laboratory conditions show overall low GPP and PR in both wet- and dry-season samples (all wetland samples were heterotrophic with GPP/PR?<?1). Despite the short-term dominance of aquatic respiration processes leading to net release of carbon in the water column under these conditions, there is appreciable long-term storage of carbon in sediment in the Kings Plains wetlands. This demonstrates the importance of wet–dry-tropics wetland systems as hotspots of carbon sequestration, locally, regionally and globally, and consideration should be given to their conservation and management in this context.

     

Naemacyclus culmigenus,a newly reported potential pathogen to Miscanthus sinensis,new to Japan

Since the summer of 2010, a discomycete with erumpent apothecia associated with a leaf blight of Miscanthus leaves, were often collected. The morphological characteristics of the fungus suggested it was a member of the Helotiales rather than the Rhytismatales and this was supported by a phylogenetic analysis. Based on a morphological comparison with the type specimen of Naemacyclus culmigenus, currently known from Poaceae (Andropogon and Panicum), it was identified as N. culmigenus, new to Japan. The molecular phylogenetic analysis showed that the generic delimitation of Naemacyclus and related species requires clarification, as does their higher classification within the Leotiomycetes.     

Protein N-Myristoylation Plays a Critical Role in the Endoplasmic Reticulum Morphological Change Induced by Overexpression of Protein Lunapark,an Integral Membrane Protein of the Endoplasmic Reticulum

N-myristoylation of eukaryotic cellular proteins has been recognized as a modification that occurs mainly on cytoplasmic proteins. In this study, we examined the membrane localization, membrane integration, and intracellular localization of four recently identified human N-myristoylated proteins with predicted transmembrane domains. As a result, it was found that protein Lunapark, the human ortholog of yeast protein Lnp1p that has recently been found to be involved in network formation of the endoplasmic reticulum (ER), is an N-myristoylated polytopic integral membrane protein. Analysis of tumor necrosis factor-fusion proteins with each of the two putative transmembrane domains and their flanking regions of protein Lunapark revealed that transmembrane domain 1 and 2 functioned as type II signal anchor sequence and stop transfer sequence, respectively, and together generated a double-spanning integral membrane protein with an N-/C-terminal cytoplasmic orientation. Immunofluorescence staining of HEK293T cells transfected with a cDNA encoding protein Lunapark tagged with FLAG-tag at its C-terminus revealed that overexpressed protein Lunapark localized mainly to the peripheral ER and induced the formation of large polygonal tubular structures. Morphological changes in the ER induced by overexpressed protein Lunapark were significantly inhibited by the inhibition of protein N-myristoylation by means of replacing Gly2 with Ala. These results indicated that protein N-myristoylation plays a critical role in the ER morphological change induced by overexpression of protein Lunapark.     

Ovarian Cancer Stem Cells Are Enriched in Side Population and Aldehyde Dehydrogenase Bright Overlapping Population

Cancer stem-like cells (CSCs)/cancer-initiaiting cells (CICs) are defined as a small population of cancer cells that have self-renewal capacity, differentiation potential and high tumor-initiating ability. CSCs/CICs of ovarian cancer have been isolated by side population (SP) analysis, ALDEFLUOR assay and using cell surface markers. However, these approaches are not definitive markers for CSCs/CICs, and it is necessary to refine recent methods for identifying more highly purified CSCs/CICs. In this study, we analyzed SP cells and aldehyde dehydrogenese bright (ALDH^Br) cells from ovarian cancer cells. Both SP cells and ALDH^Br cells exhibited higher tumor-initiating ability and higher expression level of a stem cell marker, sex determining region Y-box 2 (SOX2), than those of main population (MP) cells and ALDH^Low cells, respectively. We analyzed an SP and ALDH^Br overlapping population (SP/ALDH^Br), and the SP/ALDH^Br population exhibited higher tumor-initiating ability than that of SP cells or ALDH^Br cells, enabling initiation of tumor with as few as 10² cells. Furthermore, SP/ADLH^Br population showed higher sphere-forming ability, cisplatin resistance, adipocyte differentiation ability and expression of SOX2 than those of SP/ALDH^Low, MP/ALDH^Br and MP/ALDH^Low cells. Gene knockdown of SOX2 suppressed the tumor-initiation of ovarian cancer cells. An SP/ALDH^Br population was detected in several gynecological cancer cells with ratios of 0.1% for HEC—1 endometrioid adenocarcinoma cells to 1% for MCAS ovary mucinous adenocarcinoma cells. Taken together, use of the SP and ALDH^Br overlapping population is a promising approach to isolate highly purified CSCs/CICs and SOX2 might be a novel functional marker for ovarian CSCs/CICs.     

Skin Autofluorescence Is Associated with the Progression of Chronic Kidney Disease: A Prospective Observational Study

Background

Advanced glycation end product (AGE) accumulation is thought to be a measure of cumulative metabolic stress that has been reported to independently predict cardiovascular disease in diabetes and renal failure. The aim of this study was to evaluate the association between AGE accumulation, measured as skin autofluorescence, and the progression of renal disease in pre-dialysis patients with chronic kidney disease (CKD).

Methods

Skin autofluorescence was measured noninvasively with an autofluorescence reader at baseline in 449 pre-dialysis patients with CKD. The primary end point was defined as a doubling of serum creatinine and/or need for dialysis.

Results

Thirty-three patients were lost to follow-up. Forty six patients reached the primary end point during the follow-up period (Median 39 months). Kaplan-Meier analysis showed a significantly higher risk of development of the primary end points in patients with skin autofluorescence levels above the optimal cut-off level of 2.31 arbitrary units, derived by receiver operator curve analysis. Cox regression analysis revealed that skin autofluorescence was an independent predictor of the primary end point, even after adjustment for age, gender, smoking history, diabetes, estimated glomerular filtration rate and proteinuria (adjusted hazard ratio 2.58, P = 0.004).

Conclusions

Tissue accumulation of AGEs, measured as skin autofluorescence, is a strong and independent predictor of progression of CKD. Skin autofluorescence may be useful for risk stratification in this group of patients; further studies should clarify whether AGE accumulation could be one of the therapeutic targets to improve the prognosis of CKD.     

The Role of NF-κB Signaling in the Maintenance of Pluripotency of Human Induced Pluripotent Stem Cells

NF-κB signaling plays an essential role in maintaining the undifferentiated state of embryonic stem (ES) cells. However, opposing roles of NF-κB have been reported in mouse and human ES cells, and the role of NF-κB in human induced pluripotent stem (iPS) cells has not yet been clarified. Here, we report the role of NF-κB signaling in maintaining the undifferentiated state of human iPS cells. Compared with differentiated cells, undifferentiated human iPS cells showed an augmentation of NF-κB activity. During differentiation induced by the removal of feeder cells and FGF2, we observed a reduction in NF-κB activity, the expression of the undifferentiation markers Oct3/4 and Nanog, and the up-regulation of the differentiated markers WT-1 and Pax-2. The specific knockdown of NF-κB signaling using p65 siRNA also reduced the expression of Oct3/4 and Nanog and up-regulated WT-1 and Pax-2 but did not change the ES-like colony formation. Our results show that the augmentation of NF-κB signaling maintains the undifferentiated state of human iPS and suggest the importance of this signaling pathway in maintenance of human iPS cells.