Changes in Photochemical Efficiency and Differential Induction of Superoxide Dismutase in Response to Combined Stresses of Chilling Temperature and Relatively High Irradiation in Two <em>Chlorella</em> Strains

The green algae Chlorella sp. DT (DT) and Chlorella pyrenoidosa 211-8b (8b) had similar cell growth rates and photochemical efficiency (Fv/Fm) when they were cultivated under a moderate irradiance of 120 μmol photons m−2 s−1 in combination with a series of temperatures that decreased from 32 to 7°C. Upon shifting the cultures to the relatively high irradiance of 240 μmol photons m−2 s−1, DT exhibited higher cell growth rates than 8b under the chilling temperatures of 20°C and 15°C and differences in the Fv/Fm and Chl a/b ratios from 8b. In particular, DT possessed more new differentially induced SOD isoforms than 8b

Protein solubility and differential proteomic profiling of recombinant Escherichia coli overexpressing double-tagged fusion proteins

Abstract Background Overexpression of recombinant proteins usually triggers the induction of heat shock proteins that regulate aggregation and solubility of the overexpressed protein. The two-dimensional gel electrophoresis (2-DE)-mass spectrometry approach was used to profile the proteome of Escherichia coli overexpressing N-acetyl-D-glucosamine 2-epimerase (GlcNAc 2-epimerase) and N-acetyl-D-neuraminic acid aldolase (Neu5Ac aldolase), both fused to glutathione S-transferase (GST) and polyionic peptide (5D or 5R). Results Overexpression of fusion proteins by IPTG induction caused significant differential expression of numerous cellular proteins; most of these proteins were down-regulated, including enzymes connected to the pentose phosphate pathway and the enzyme LuxS that could lead to an inhibition of tRNA synthesis. Interestingly, when plasmid-harboring cells were cultured in LB medium, gluconeogenesis occurred mainly through MaeB, while in the host strain, gluconeogenesis occurred by a different pathway (by Mdh and PckA). Significant up-regulation of the chaperones ClpB, HslU and GroEL and high-level expression of two protective small heat shock proteins (IbpA and IbpB) were found in cells overexpressing GST-GlcNAc 2-epimerase-5D but not in GST-Neu5Ac aldolase-5R-expressing E. coli. Although most of the recombinant protein was present in insoluble aggregates, the soluble fraction of GST-GlcNAc 2-epimerase-5D was higher than that of GST-Neu5Ac aldolase-5R. Also, in cells overexpressing recombinant GST-GlcNAc 2-epimerase-5D, the expression of σ32 was maintained at a higher level following induction. Conclusions Differential expression of metabolically functional proteins, especially those in the gluconeogenesis pathway, was found between host and recombinant cells. Also, the expression patterns of chaperones/heat shock proteins differed among the plasmid-harboring bacteria in response to overproduction of recombinant proteins. In conclusion, the solubility of overexpressed recombinant proteins could be enhanced by maintaining the expression of σ32, a bacterial heat shock transcription factor, at higher levels during overproduction.</p

Gamified mathematics practice: Designing with e-commerce and computational concepts.

learning Mathematics: first, students who face difficulty understanding and are too shy to participate in discussions and subsequently do not manage to resolve their doubts, and second, dull e-learning websites. The many rules in Mathematics compounds the problem further. We thus aim to address these problems through a gamified-commerce oriented Mathematics learning practice system, Alzebra, for informal learning. Focusing on principles of Information Systems Analysis and Design, e-commerceoriented computational concepts are embedded in the game to motivate online practice. The system concept, design methodology and user testing outcomes are presented. Significance lies in deriving perception towards gamification and components which users liked or disliked and the efficacy of our hybrid approach in systems development

Detection of Diatomic Carbon in 2I/Borisov

2I/Borisov is the first-ever observed interstellar comet (and the second detected interstellar object (ISO)). It was discovered on 2019 August 30 and has a heliocentric orbital eccentricity of ~3.35, corresponding to a hyperbolic orbit that is unbound to the Sun. Given that it is an ISO, it is of interest to compare its properties—such as composition and activity—with the comets in our solar system. This study reports low-resolution optical spectra of 2I/Borisov. The spectra were obtained by the MDM Observatory Hiltner 2.4 m telescope/Ohio State Multi-Object Spectrograph (on 2019 October 31.5 and November 4.5, UT). The wavelength coverage spanned from 3700 to 9200 Å. The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum (compared to the red). The spectra of 2I/Borisov clearly show CN emission at 3880 Å, as well as C2 emission at both 4750 and 5150 Å. Using a Haser model to covert the observed fluxes into estimates for the molecular production rates, we find Q(CN) = 2.4 ± 0.2 × 10²⁴ s⁻¹, and Q(C₂) = (5.5 ± 0.4) × 10²³ s⁻¹ at the heliocentric distance of 2.145 au. Our Q(CN) estimate is consistent with contemporaneous observations, and the Q(C₂) estimate is generally below the upper limits of previous studies. We derived the ratio Q(C₂)/Q(CN) = 0.2 ± 0.1, which indicates that 2I/Borisov is depleted in carbon-chain species, but is not empty. This feature is not rare for the comets in our solar system, especially in the class of Jupiter-family comets

A neuronal death model: overexpression of neuronal intermediate filament protein peripherin in PC12 cells

<p>Abstract</p> <p>Background</p> <p>Abnormal accumulation of neuronal intermediate filament (IF) is a pathological indicator of some neurodegenerative disorders. However, the underlying neuropathological mechanisms of neuronal IF accumulation remain unclear. A stable clone established from PC12 cells overexpressing a GFP-Peripherin fusion protein (pEGFP-Peripherin) was constructed for determining the pathway involved in neurodegeneration by biochemical, cell biology, and electronic microscopy approaches. In addition, pharmacological approaches to preventing neuronal death were also examined.</p> <p>Results</p> <p>Results of this study showed that TUNEL positive reaction could be detected in pEGFP-Peripherin cells. Swollen mitochondria and endoplasmic reticulum (ER) were seen by electron microscopy in pEGFP-Peripherin cells on day 8 of nerve growth factor (NGF) treatment. Peripherin overexpression not only led to the formation of neuronal IF aggregate but also causes aberrant neuronal IF phosphorylation and mislocation. Western blots showed that calpain, caspase-12, caspase-9, and caspase-3 activity was upregulated. Furthermore, treatment with calpain inhibitor significantly inhibited cell death.</p> <p>Conclusions</p> <p>These results suggested that the cytoplasmic neuronal IF aggregate caused by peripherin overexpression may induce aberrant neuronal IF phosphorylation and mislocation subsequently trapped and indirectly damaged mitochondria and ER. We suggested that the activation of calpain, caspase-12, caspase-9, and caspase-3 were correlated to the dysfunction of the ER and mitochondria in our pEGFP-Peripherin cell model. The present study suggested that pEGFP-Peripherin cell clones could be a neuronal death model for future studies in neuronal IFs aggregate associated neurodegeneration.</p

Epidermal growth factor receptor regulates β-catenin location, stability, and transcriptional activity in oral cancer

<p>Abstract</p> <p>Background</p> <p>Many cancerous cells accumulate β-catenin in the nucleus. We examined the role of epidermal growth factor receptor (EGFR) signaling in the accumulation of β-catenin in the nuclei of oral cancer cells.</p> <p>Results</p> <p>We used two strains of cultured oral cancer cells, one with reduced EGFR expression (OECM1 cells) and one with elevated EGFR expression (SAS cells), and measured downstream effects, such as phosphorylation of β-catenin and GSK-3β, association of β-catenin with E-cadherin, and target gene regulation. We also studied the expression of EGFR, β-catenin, and cyclin D1 in 112 samples of oral cancer by immunostaining. Activation of EGFR signaling increased the amount of β-catenin in the nucleus and decreased the amount in the membranes. EGF treatment increased phosphorylation of β-catenin (tyrosine) and GSK-3β(Ser-(9), resulting in a loss of β-catenin association with E-cadherin. TOP-FLASH and FOP-FLASH reporter assays demonstrated that the EGFR signal regulates β-catenin transcriptional activity and mediates cyclin D1 expression. Chromatin immunoprecipitation experiments indicated that the EGFR signal affects chromatin architecture at the regulatory element of cyclin D1, and that the CBP, HDAC1, and Suv39h1 histone/chromatin remodeling complex is involved in this process. Immunostaining showed a significant association between EGFR expression and aberrant accumulation of β-catenin in oral cancer.</p> <p>Conclusions</p> <p>EGFR signaling regulates β-catenin localization and stability, target gene expression, and tumor progression in oral cancer. Moreover, our data suggest that aberrant accumulation of β-catenin under EGFR activation is a malignancy marker of oral cancer.</p

Did the S.A.R.S. epidemic weaken the integration of Asian stock markets? Evidence from smooth time-varying cointegration analysis

The purpose of this study is to examine the effect of the Severe Acute Respiratory Syndrome (S.A.R.S.) epidemic on the long-run relationship between China and four Asian stock markets. To this end, we first employ the advanced smooth time-varying cointegration model to investigate the existence of a time-varying cointegration relation among these markets and then employ the difference-indifferences approach to analyse whether or not the S.A.R.S. epidemic impacted the long-run relation between China and these four markets during the period 1998–2008, covering 5 years before and after the S.A.R.S. outbreak. Our results support the existence of a time-varying cointegration relation in the aggregate stock price indices, and that the S.A.R.S. epidemic did weaken the long-run relationship between China and the four markets. Therefore, stockholders and policy makers should be concerned about the influence of catastrophic epidemic diseases on the financial integration of stock market in Asia