8-Hydroxydeoxyguanosine induces senescence-like changes in KG-1, human acute myelocytic leukemia cell line

8-Hydroxydeoxyguanosine (oh⁸dG) treatment induced senescence-like changes in KG-1 cells, a human acute myelocytic leukemia cell line. The oh⁸dG-treated cells stained positive for senescence associated β-galactosidase (SA-β-galactosidase) and had enlarged cell shape, both of which are senescence indexes. The oh⁸dG-treated cells were also cell growth inhibited and arrested at G₁ in the cell cycle. The accumulation of cdk (cyclin dependent kinase) inhibitors, such as p16, p21, and p27, also implies that cellular senescence was induced in oh⁸dG-treated cells. However, these changes were not accompanied by cell differentiation or telomerase activity. Taken together, we conclude that oh⁸dG treatment of KG-1 cells induces cellular senescence.     

Biodegradable molecularly imprinted polymers based on poly(ε-caprolactone)

Novel biodegradable molecularly imprinted polymers (MIPs) based on poly(ε-caprolactone) (PCL) were prepared by combining two important properties required of ideal biomaterials, biodegradability (with biocompatibility) and molecular recognition properties. Acrylate or methacrylate end-capped PCL macromers were synthesized through the reaction of PCL diol or triol with acryloyl or methacryloyl chloride. The synthesis of acrylate or methacrylate end-capped macromers was confirmed using FT-IR and H NMR spectroscopic techniques. These macromers were used to prepare biodegradable crosslinked networks by photopolymerization with functional monomer (acrylic acid) and a model template (theophylline). The theophylline-imprinted polymer showed higher binding capacity for theophylline compared with non-imprinted polymer (NIP), and also showed selectivity for theophylline over caffeine (similar structure molecules). PCL-based MIP degraded 8% of the initial weight in 30 days in phosphate-buffered saline (PBS) solution (pH 7.4) and over 90% of the initial weight within 24 h in 1 N NaOH at 37°C.     

Convergent evolution of eye ultrastructure and divergent evolution of vision-mediated predatory behaviour in jumping spiders

All jumping spiders have unique, complex eyes with exceptional spatial acuity and some of the most elaborate vision-guided predatory strategies ever documented for any animal of their size. However, it is only recently that phylogenetic techniques have been used to reconstruct the relationships and key evolutionary events within the Salticidae. Here, we used data for 35 species and six genes (4.8 kb) for reconstructing the phylogenetic relationships between Spartaeinae, Lyssomaninae and Salticoida. We document a remarkable case of morphological convergence of eye ultrastructure in two clades with divergent predatory behaviour. We, furthermore, find evidence for a stepwise, gradual evolution of a complex predatory strategy. Divergent predatory behaviour ranges from cursorial hunting to building prey-catching webs and araneophagy with web invasion and aggressive mimicry. Web invasion and aggressive mimicry evolved once from an ancestral spartaeine that was already araneophagic and had no difficulty entering webs due to glue immunity. Web invasion and aggressive mimicry was lost once, in Paracyrba, which has replaced one highly specialized predation strategy with another (hunting mosquitoes). In contrast to the evolution of divergent behaviour, eyes with similarly high spatial acuity and ultrastructural design evolved convergently in the Salticoida and in Portia.     

Low-dose radiation stimulates the proliferation of normal human lung fibroblasts via a transient activation of Raf and Akt

The biological effects of low-dose radiation have been investigated and debated for more than a century, but its cellular effects and regulatory mechanisms remain poorly understood. This study shows the human cellular responses to low-dose radiation in CCD-18 Lu cells, which are derived from normal human lung fibroblasts. We examined a colony-forming assay for cell survival by ionizing radiation. Live cell counting and cell cycle analysis were measured for cell proliferation and cell cycle progression following low-dose irradiation. We examined Raf and Akt phosphorylation to determine the proliferation mechanism resulting from low-dose radiation. We also observed that p53 and p21 were related to cell cycle response. We found that 0.05 Gy of ionizing radiation enhanced cell proliferation and did not change the progression of the cell cycle. In addition, 0.05 Gy of ionizing radiation transiently activated Raf and Akt, but did not change phospho-p53, p53 and p21 in CCD-18 Lu cells. However, 2 Gy of ionizing radiation induced cell cycle arrest, phosphorylation of p53, and expression of p53 and p21. The phosphorylation of Raf and Akt proteins induced by 0.05 Gy of ionizing radiation was abolished by pre-treatment with an EGFR inhibitor, AG1478, or a PI3k inhibitor, LY294002. Cell proliferation stimulated by 0.05 Gy of ionizing radiation was blocked by the suppression of Raf and Akt phosphorylation with these inhibitors. These results suggest that 0.05 Gy of ionizing radiation stimulates cell proliferation through the transient activation of Raf and Akt in CCD-18 Lu cells.     

Effects of culture conditions on osteogenic differentiation in human mesenchymal stem cells

Human bone marrow-derived mesenchymal stem cells (hBMMSCs) must differentiate into osteogenic cells to allow for successful bone regeneration. In this study, we investigated the effects of different combinations of three soluble osteogenic differentiation-inducing factors [L-ascorbic acid (AC), beta-glycerophosphate (betaG), and bone morphogenic protein-2 (BMP-2)] and the presence of a hydroxyapatite (HA) substrate on hBMMSC osteogenic differentiation in vitro. hBMMSCs were cultured in medium containing various combinations of the soluble factors on culture plates with or without HA coating. After 7 days of culture, alkaline phosphatase (ALP) activity, calcium deposition, and osteoprotegerin (OPG) and osteopontin (OPN) expression were measured. The effects of individual and combined factors were evaluated using a factorial analysis method. BMP-2 predominantly affected expression of early markers of osteogenic differentiation (ALP and OPG). HA had the highest positive effect on OPN expression and calcium deposition. The interaction between AC, betaG, and HA had the second highest positive effect on ALP activity.     

Synthesis and characterization of a new bioactivated paramagnetic gadolinium(III) complex [Gd(DOTA-FPG)(H2O)] for tracing gene expression

A smart contrast agent for magnetic resonance imaging (MRI) can be used to exploit an enzymatic activity specific to the tissue or disease state signified by converting an MRI-inactivated agent to an activated MRI agent. In this study, a beta-galactopyranose-containing gadolinium(III) complex [Gd(DOTA-FPG)(H 2O)] was designed, synthesized, and characterized as being potentially suitable for a bioactivated MRI contrast agent. The (17)O NMR experiments were conducted to estimate the water exchange rate k e x 298 and rotational correlation time tau R 298 . The k ex 298 value of [Gd(DOTA-FPG)(H 2O)] is similar to that of [Gd(DO3A-bz-NO 2)(H 2O)]. The rotational correlation time value of [Gd(DOTA-FPG)(H 2O)] is dramatically longer than that of [Gd(DOTA)(H 2O)] (-) Relaxometric studies show that the percentage change in the T 1 value of [Gd(DOTA-FPG)(H 2O)] decreases dramatically in the presence of beta-galactosidase and human serum albumin. The T(1) change percentage of [Gd(DOTA-FPG)(H 2O)] (60%) is significantly higher than those of Egad and gadolinium(III)-1-(4-(2-(1-(4,7,10-triscarboxymethyl-(1,4,7,10-tetraazacyclododecyl)))-ethylcarbamoyloxymethyl)-2-nitrophenyl)-beta- d-glucopyronuronate. The signal intensity of the MR image for [Gd(DOTA-FPG)(H 2O)] in the presence of human serum albumin and beta-galactosidase (2670 +/- 210) is significantly higher than that of [Gd(DOTA-FPG)(H 2O)] in the sodium phosphate buffer solution (1490 +/- 160). In addition, the MR images show a higher-intensity enhancement in CT26/beta-gal tumor with beta-galactosidase gene expression but not for the CT26 tumor without beta-galactosidase gene expression. We conclude that [Gd(DOTA-FPG)(H 2O)] is a suitable candidate for a bioactivated MRI contrast agent in tracing gene expression.     

Quantitative profiling of histone post-translational modifications by stable isotope labeling

Methods for accurately quantitating changes in histone post-translational modifications are necessary for developing an understanding of how their dynamic nature influences nuclear events involving access to genomic DNA. This article describes methods for the use of in vivo stable isotope label incorporation for quantitating the levels of modification at specific residues in histone proteins. These methods are applicable to a wide variety of model systems and examples of their use in both mammalian cells and Saccharomyces cerevisiae are presented.