Effects of tachyplesin on the morphology and ultrastructure of human gastric carcinoma cell line BGC-823

AIM To investigate the morphological and ultrastructural changes in the human gastric carcinoma cell line BGC-S23 after being treated with tachyplesin, METHODS Tachyplesin was isolated from acid extracts of Chinese horseshoe crab (Tachypleus tridentatus) hemocytes, BGC-823 cells and the cells treated with 2.0 mg/L tachyplesin were examined respectively under light microscope, scanning and transmission electron microscope. RESULTS BGC-823 cells had undergone the restorational alteration in morphology and ultrastructure after tachyplesin treatment. The changes were as follows: the shape of cells was unanimous, the volume enlarged and cells turned to be flat and spread, the nucleocytoplasmic ratio lessened and nuclear shape became rather regular, the number of nucleolus reduced and its volume lessened, heterchromatin decreased while euchromatin increased in nucleus. In the cytoplasm, mitochondria grew in number with consistent structure relatively, Golgi complex turned to be typical and well-developed, rough endoplasmic reticulum increased and polyribosome decreased. The microvilli at cellular surface were rare and the filopodia reduced while lamellipodia increased at the cell edge. CONCLUSION Tachyplesin could alter the malignant morphological and ultrastructural characteristics of human gastric carcinoma cells effectively and have a certain inducing differentiation effect on human gastric carcinoma cells

Interaction between karst terrain and bauxites : evidence from Quaternary orebody distribution in Guangxi, SW China.

Research Article. Geology. 2017.Abstract available in PDF file

A facile chemical conversion synthesis of Sb2S3 nanotubes and the visible light-driven photocatalytic activities

We report a simple chemical conversion and cation exchange technique to realize the synthesis of Sb2S3 nanotubes at a low temperature of 90°C. The successful chemical conversion from ZnS nanotubes to Sb2S3 ones benefits from the large difference in solubility between ZnS and Sb2S3. The as-grown Sb2S3 nanotubes have been transformed from a weak crystallization to a polycrystalline structure via successive annealing. In addition to the detailed structural, morphological, and optical investigation of the yielded Sb2S3 nanotubes before and after annealing, we have shown high photocatalytic activities of Sb2S3 nanotubes for methyl orange degradation under visible light irradiation. This approach offers an effective control of the composition and structure of Sb2S3 nanomaterials, facilitates the production at a relatively low reaction temperature without the need of organics, templates, or crystal seeds, and can be extended to the synthesis of hollow structures with various compositions and shapes for unique properties

Study of deposition parameters for the fabrication of ZnO thin films using femtosecond laser

Femtosecond (fs) pulsed laser deposition (fs-PLD) of ZnO thin film on borosilicate glass substrates is reported in this work. The effect of important fs-PLD parameters such as target–substrate distance, laser pulse energy and substrate temperature on structure, morphology, optical transparency and luminescence of as-deposited films is discussed. XRD analysis reveals that all the films grown using the laser energy range 120–230 μJ are polycrystalline when they are deposited at room temperature in a ~10−5 Torr vacuum. Introducing 0.7 mTorr oxygen pressure, the films show preferred c-axis growth and transform into a single-crystal-like film when the substrate temperature is increased to 100 °C. The scanning electron micrographs show the presence of small nano-size grains at 25 °C, which grow in size to the regular hexagonal shape particles at 100 °C. Optical transmission of the ZnO film is found to increase with an increase in crystal quality. Maximum transmittance of 95 % in the wavelength range 400–1400 nm is achieved for films deposited at 100 °C employing a laser pulse energy of 180 μJ. The luminescence spectra show a strong UV emission band peaked at 377 nm close to the ZnO band gap. The shallow donor defects increase at higher pulse energies and higher substrate temperatures, which give rise to violet-blue luminescence. The results indicate that nano-crystalline ZnO thin films with high crystalline quality and optical transparency can be fabricated by using pulses from fs lasers

Natural Selection and Adaptive Evolution of Leptin in the Ochotona Family Driven by the Cold Environmental Stress

BACKGROUND: Environmental stress can accelerate the evolutionary rate of specific stress-response proteins and create new functions specialized for different environments, enhancing an organism's fitness to stressful environments. Pikas (order Lagomorpha), endemic, non-hibernating mammals in the modern Holarctic Region, live in cold regions at either high altitudes or high latitudes and have a maximum distribution of species diversification confined to the Qinghai-Tibet Plateau. Variations in energy metabolism are remarkable for them living in cold environments. Leptin, an adipocyte-derived hormone, plays important roles in energy homeostasis. METHODOLOGY/PRINCIPAL FINDINGS: To examine the extent of leptin variations within the Ochotona family, we cloned the entire coding sequence of pika leptin from 6 species in two regions (Qinghai-Tibet Plateau and Inner Mongolia steppe in China) and the leptin sequences of plateau pikas (O. curzonia) from different altitudes on Qinghai-Tibet Plateau. We carried out both DNA and amino acid sequence analyses in molecular evolution and compared modeled spatial structures. Our results show that positive selection (PS) acts on pika leptin, while nine PS sites located within the functionally significant segment 85-119 of leptin and one unique motif appeared only in pika lineages-the ATP synthase alpha and beta subunit signature site. To reveal the environmental factors affecting sequence evolution of pika leptin, relative rate test was performed in pikas from different altitudes. Stepwise multiple regression shows that temperature is significantly and negatively correlated with the rates of non-synonymous substitution (Ka) and amino acid substitution (Aa), whereas altitude does not significantly affect synonymous substitution (Ks), Ka and Aa. CONCLUSIONS/SIGNIFICANCE: Our findings support the viewpoint that adaptive evolution may occur in pika leptin, which may play important roles in pikas' ecological adaptation to extreme environmental stress. We speculate that cold, and probably not hypoxia, may be the primary environmental factor for driving adaptive evolution of pika leptin