Carbon nanomaterials (CNMs), which include carbon nanotubes (CNTs) and their derivatives, have diverse technological and biomedical applications. The potential toxicity of CNMs to cells and tissues has become an important emerging question in nanotechnology. To assess the toxicity of CNTs and fullerenol C60(OH)24, we in the present work used the budding yeast Saccharomyces cerevisiae, one of the simplest eukaryotic organisms that share fundamental aspects of eukaryotic cell biology. We found that treatment with CNMs, regardless of their physical shape, negatively affected the growth rates, end-point cell densities and doubling times of CNM-exposed yeast cells when compared to unexposed cells. To investigate potential mechanisms behind the CNMs-induced growth defects, we performed RNA-Seq dependent transcriptional analysis and constructed global gene expression profiles of fullerenol C60(OH)24- and CNT-treated cells. When compared to non-treated control cells, CNM-treated cells displayed differential expression of genes whose functions are implicated in membrane transporters and stress response, although differentially expressed genes were not consistent between CNT- and fullerenol C60(OH)24-treated groups, leading to our conclusion that CNMs could serve as environmental toxic factors to eukaryotic cells.
Recent literature demonstrates that platinum-based chemotherapeutic drugs in physiological solvents display higher efficacy in destabilizing cancer cells.As human cancer cells come in over 200 different varieties, it would be beneficial to test the efficacy of these drugs using a wider spectrum of cells.Utilizing the well-tested HeLa cervical cancer cells as a control for the effects of these drugs, we assessed the impact of platinum-based cisplatin, carboplatin, and oxaliplatin on ML-1 thyroid cancer cells.Through the XTT Viability assay, we found that ML-1 cells are more resistant to cisplatin and oxaliplatin with an IC 50 value at least four times higher than those for the same drugs in HeLa cells.It has been consistently shown that the oxidative stress caused by these chemicals was more pronounced in HeLa cells than in ML-1 cells, but the only measurable results were found 24 hours after treatment.We also show that a high percentage of HeLa cells displayed apoptosis with even 20 µM of these chemicals, which is directly comparable in effect to the 100 µM of chemicals in ML-1 cells.Upon comparing the expression levels of pro-apoptotic enzymes in HeLa and ML-1 cells, we observed that when treated with 40 µM of these chemicals, the levels of pro-apoptotic enzymes were statistically higher for HeLa cells than for ML-1 cells.Our research will provide new insight into the different capacities of each cell line and the treatment regimen for cancer patients in the future.
The mechanism by which capping protein (CP) binds barbed ends of actin filaments is not understood, and the physiological significance of CP binding to actin is not defined. The CP crystal structure suggests that the COOH-terminal regions of the CP alpha and beta subunits bind to the barbed end. Using purified recombinant mutant yeast CP, we tested this model. CP lacking both COOH-terminal regions did not bind actin. The alpha COOH-terminal region was more important than that of beta. The significance of CP's actin-binding activity in vivo was tested by determining how well CP actin-binding mutants rescued null mutant phenotypes. Rescue correlated well with capping activity, as did localization of CP to actin patches, indicating that capping is a physiological function for CP. Actin filaments of patches appear to be nucleated first, then capped with CP. The binding constants of yeast CP for actin suggest that actin capping in yeast is more dynamic than in vertebrates.
Abstract Hydrophobic polyhedral oligomeric silsesquioxane (POSS) molecules were utilized for the surface coating to improve the hydrophobicity of the surface of phosphate glass (Pglass). To maximize the Pglass surface hydrophobicity, protrusions on the Pglass surface were successfully prepared by Pglass particles on the surface of the bulk Pglass to mimick the lotus leaf, which has a superhydrophobic surface. The results showed that the combination of hydrophobic coating by POSS and improved roughness prepared by Pglass particles with air trapped on the Pglass surface yielded significantly increased hydrophobicity close to superhydrophobicity of lotus leaf. Chemical stability tests using ethanol and acetone confirmed stability of POSS on the Pglass surface. This result was supported by the XPS data showing an increase of bridging oxygen on the Pglass surface due to the condensation reaction between the hydroxyly functional groups of the Pglass and POSS. The relatively longer hydrophobic functional group of isooctyl compared to that of the isobutyl on the POSS cages gave larger contact angles than that of conventional silane, indicating that the POSS chemicals used are able to effectively produce the so-called “umbrella effect” mechanism that covers the intrincic hydrophilic surface of the phosphate glass using bulky molecules and grafted hydrophobic POSS chemical functional groups.
Retrieval of cargo proteins from the endosome towards the trans-Golgi network (TGN) is a crucial intracellular process for cellular homeostasis. Its dysfunction is associated with pathogenesis of Alzheimer and Parkinson's diseases. Myosin family proteins are cellular motors walking along actin filaments by utilizing the chemical energy from ATP hydrolysis, known to involve in pleiotropic cellular trafficking pathways. However, the question of whether myosins play a role in the trafficking of Snc1 and Vps10 has not been addressed yet. The present study assesses the potential roles of all five yeast myosins in the recycling of two membrane cargo, Snc1 and Vps10. It appears that all myosins except Myo2 are not required for the Snc1 traffic, while it was found that Myo1 and 2 play important roles for Vps10 retrieval from the endosome and the vacuole. Multiple myo2 mutants harboring a point mutation in the actin binding or the cargo binding tail domain were characterized to demonstrate abnormal Vps10-GFP and GFP-Snc1 distribution phenotypes, suggesting a severe defect in their sorting and trafficking at the endosome. Furthermore, Vps10-GFP patches in all tested myo2 mutants were found to be near stationary with quantitative live cell imaging. Finally, we found that actin cables in the myo2 mutant cells were considerably disrupted, which may aggravate the trafficking of Vps10 from the endosome. Together, our results provide novel insights into the function of Myo-family proteins in the recycling traffic of Vps10 and Snc1 destined for the TGN.
While the presence of dynamic neuromuscular stabilization (DNS) has been provided as an important component of the integrated spinal stabilization and associated abdominal stabilization prior to dynamic movement, no previous study has investigated the spinal mechanical effects scoliosis and pain control in youth baseball player with scoliosis. This study compared the effects of gymball exercise, with and without DNS core stability exercise, on spine kinematics and pain control in youth baseball player with scoliosis. A total of 28 participants with scoliosis were randomized into gymball exercise, with and without DNS core stability exercise. Clinical outcomes included the Cobb’s angle and visual analog scale (VAS). Two-way repeated analysis of variance (ANOVA) was conducted at p < 0.05. Two-way repeated ANOVA showed that gymball with DNS showed superior effects, compared to gymball without DNS, on Cobb’s angle (P < 0.001), but not on VAS (P < 0.837). Our results provide novel, promising clinical evidence that DNS improved scoliosis kinematics as well as pain control in youth baseball player with scoliosis.
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