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71.
Air-breathing divers are assumed to have evolved to apportion their time between surface and underwater periods to maximize the benefit gained from diving activities. However, whether they change their time allocation depending on the aim of the dive is still unknown. This may be particularly crucial for ‘surfacers’ because they dive for various purposes in addition to foraging. In this study, we counted breath events at the surface and estimated oxygen consumption during resting, foraging and other dives in 11 green turtles (Chelonia mydas) in the wild. Breath events were counted by a head-mounted acceleration logger or direct observation based on an animal-borne video logger, and oxygen consumption was estimated by measuring overall dynamic body acceleration. Our results indicate that green turtles maximized their submerged time, following this with five to seven breaths to replenish oxygen for resting dives. However, they changed their dive tactic during foraging and other dives; they surfaced without depleting their estimated stores of oxygen, followed by only a few breaths for effective foraging and locomotion. These dichotomous surfacing tactics would be the result of behavioural modifications by turtles depending on the aim of each dive.  相似文献   
72.
Fluorescence enhancement monitoring of pyrromethene laser dyes using their complexation with Ag nanoparticles (Ag NPs) was studied. The size of the prepared Ag NPs was determined by transmission electron spectroscopy and UV/Vis absorption spectroscopy. Mie theory was also used to confirm the size of NPs theoretically. The effect of different nanoparticle concentrations on the optical properties of 1 × 10‐4 M PM dyes shows that 40%of Ag NPs concentration (40%C Ag NPs) in complex is the optimum concentration. Also, the effects of different concentrations of PM dyes in a complex was measured. Emission enhancement factors were calculated for all samples. Fluorescence enhancement efficiencies depended on the input pumping energy of a Nd‐YAG laser (wavelength 532 nm and 8 ns pulse duration) were reported and showed the lowest energy (28 and 32 mJ) in the case of PM567 and PM597, respectively. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
73.
Intravenous immunoglobulin (IVIG) is the first line treatment for Guillain–Barré syndrome and multifocal motor neuropathy, which are caused by anti-ganglioside antibody-mediated complement-dependent cytotoxicity. IVIG has many potential mechanisms of action, and sialylation of the IgG Fc portion reportedly has an anti-inflammatory effect in antibody-dependent cell-mediated cytotoxicity models. We investigated the effects of different IVIG glycoforms on the inhibition of antibody-mediated complement-dependent cytotoxicity. Deglycosylated, degalactosylated, galactosylated and sialylated IgG were prepared from IVIG following treatment with glycosidases and glycosyltransferases. Sera from patients with Guillain–Barré syndrome, Miller Fisher syndrome and multifocal motor neuropathy associated with anti-ganglioside antibodies were used. Inhibition of complement deposition subsequent to IgG or IgM autoantibody binding to ganglioside, GM1 or GQ1b was assessed on microtiter plates. Sialylated and galactosylated IVIGs more effectively inhibited C3 deposition than original IVIG or enzyme-treated IVIGs (agalactosylated and deglycosylated IVIGs). Therefore, sialylated and galactosylated IVIGs may be more effective than conventional IVIG in the treatment of complement-dependent autoimmune diseases.  相似文献   
74.
Visceral fat adiposity plays an important role in the development of metabolic syndrome. We reported previously the impact of human visceral fat adiposity on gene expression profile of peripheral blood cells. Genes related to circadian rhythm were highly associated with visceral fat area and period homolog 1 (PER1) showed the most significant negative correlation with visceral fat area. However, regulation of adipose Per1 remains poorly understood. The present study was designed to understand the regulation of Per1 in adipose tissues. Adipose Per1 mRNA levels of ob/ob mice were markedly low at 25 and 35 weeks of age. The levels of other core clock genes of white adipose tissues were also low in ob/ob mice at 25 and 35 weeks of age. Per1 mRNA was mainly expressed in the mature adipocyte fraction (MAF) and it was significantly low in MAF of ob/ob mice. To examine the possible mechanisms, 3T3-L1 adipocytes were treated with H2O2, tumor necrosis factor-α (TNF-α), S100A8, and lipopolysaccharide (LPS). However, no significant changes in Per1 mRNA level were observed by these agents. Exposure of cultured 3T3-L1 adipocytes to low temperature (33°C) decreased Per1 and catalase, and increased monocyte chemoattractant protein-1 (Mcp-1) mRNA levels. Hypothermia also worsened insulin-mediated Akt phosphorylation in 3T3-L1 adipocytes. Finally, telemetric analysis showed low temperature of adipose tissues in ob/ob mice. In obesity, adipose hypothermia seems to accelerate adipocyte dysfunction.  相似文献   
75.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been transmitted across all over the world, in contrast to the limited epidemic of genetically- and virologically-related SARS-CoV. However, the molecular basis explaining the difference in the virological characteristics among SARS-CoV-2 and SARS-CoV has been poorly defined. Here we identified that host sialoglycans play a significant role in the efficient spread of SARS-CoV-2 infection, while this was not the case with SARS-CoV. SARS-CoV-2 infection was significantly inhibited by α2-6-linked sialic acid-containing compounds, but not by α2–3 analog, in VeroE6/TMPRSS2 cells. The α2-6-linked compound bound to SARS-CoV-2 spike S1 subunit to competitively inhibit SARS-CoV-2 attachment to cells. Enzymatic removal of cell surface sialic acids impaired the interaction between SARS-CoV-2 spike and angiotensin-converting enzyme 2 (ACE2), and suppressed the efficient spread of SARS-CoV-2 infection over time, in contrast to its least effect on SARS-CoV spread. Our study provides a novel molecular basis of SARS-CoV-2 infection which illustrates the distinctive characteristics from SARS-CoV.  相似文献   
76.
77.
Formation of foreign body giant cells (FBGCs) occurs following implantation of medical devices such as artificial joints and is implicated in implant failure associated with inflammation or microbial infection. Two major macrophage subpopulations, M1 and M2, play different roles in inflammation and wound healing, respectively. Therefore, M1/M2 polarization is crucial for the development of various inflammation-related diseases. Here, we show that FBGCs do not resorb bone but rather express M2 macrophage-like wound healing and inflammation-terminating molecules in vitro. We also found that FBGC formation was significantly inhibited by inflammatory cytokines or infection mimetics in vitro. Interleukin-1 receptor-associated kinase-4 (IRAK4) deficiency did not alter osteoclast formation in vitro, and IRAK4-deficient mice showed normal bone mineral density in vivo. However, IRAK4-deficient mice were protected from excessive osteoclastogenesis induced by IL-1β in vitro or by LPS, an infection mimetic of Gram-negative bacteria, in vivo. Furthermore, IRAK4 deficiency restored FBGC formation and expression of M2 macrophage markers inhibited by inflammatory cytokines in vitro or by LPS in vivo. Our results demonstrate that osteoclasts and FBGCs are reciprocally regulated and identify IRAK4 as a potential therapeutic target to inhibit stimulated osteoclastogenesis and rescue inhibited FBGC formation under inflammatory and infectious conditions without altering physiological bone resorption.  相似文献   
78.
The insecticidal crystal protein (ICP) gene, icp, from a 68-kb plasmid derived from Bacillus thuringiensis subsp. sotto was cloned in Escherichia coli. The icp expression in E. coli cells was confirmed by both immunological and insect-toxicity assays of the cell extract. The entire icp gene resides in the 6.6-kb PstI fragment, which codes for a 144-kDal peptide identical to the intact ICP, as determined by its size and reaction with anti-ICP antibody. Deletion analysis further revealed that the 2.8-kb region within the 6.6-kb PstI fragment codes for ICP. Analysis of the nucleotide sequence indicated that a peptide of 934 amino acid residues truncated at the C-terminal end is encoded by this 2.8-kb fragment. A unique feature of this truncated ICP is the abundance of cysteine and lysine residues within its C-terminal region.  相似文献   
79.
Epigenetic alterations underlie various human disorders, including cancer, and this has resulted in the development of drugs targeting epigenetic alterations. Although DNA demethylating agents are one of the major epigenetic drugs, only two compounds—5-azacytidine (5-aza-CR, azacitidine) and 5-aza-2'-deoxycytidine (5-aza-dC, decitabine)—have obtained clinical approval. Here, we aimed to establish a detection system for DNA demethylating agents suitable for a high-throughput screening (HTS) in mammalian cells. We inserted luciferase and EGFP reporter genes under the UCHL1 promoter, which is methylation-silenced in human colon cancers and can be readily demethylated to drive strong expression. Methylated UCHL1 promoter was introduced into HCT116 colon cancer cells, and transfectants with methylated exogenous UCHL1 promoter were obtained. By screening subclones from each of the epigenetically heterogeneous transfectant clones, we finally obtained three optimal subclones that expressed luciferase and EGFP after 5-aza-dC treatment with high signal-to-noise ratios. Nucleosomes with H3K9me2 were present around the exogenous UCHL1 promoter in all three subclones. Using one of the subclones (HML58-3), HTS was conducted using 19,840 small molecules. Two hit compounds were obtained, and these turned out to be 5-aza-dC and 5-aza-CR. The assay system constructed here demonstrates a robust response to DNA demethylating agents, along with high specificity, and will be useful for screening and biological assays in epigenetics.  相似文献   
80.
Architectural DNA-binding proteins function to regulate diverse DNA reactions and have the defining property of significantly changing DNA conformation. Although the 1D movement along DNA by other types of DNA-binding proteins has been visualized, the mobility of architectural DNA-binding proteins on DNA remains unknown. Here, we applied single-molecule fluorescence imaging on arrays of extended DNA molecules to probe the binding dynamics of three structurally distinct architectural DNA-binding proteins: Nhp6A, HU, and Fis. Each of these proteins was observed to move along DNA, and the salt concentration independence of the 1D diffusion implies sliding with continuous contact to DNA. Nhp6A and HU exhibit a single sliding mode, whereas Fis exhibits two sliding modes. Based on comparison of the diffusion coefficients and sizes of many DNA binding proteins, the architectural proteins are categorized into a new group distinguished by an unusually high free-energy barrier for 1D diffusion. The higher free-energy barrier for 1D diffusion by architectural proteins can be attributed to the large DNA conformational changes that accompany binding and impede rotation-coupled movement along the DNA grooves.  相似文献   
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