Both sitagliptin analogue & pioglitazone preserve the beta-cell proportion in the islets with different mechanism in non-obese and obese diabetic mice

In this study, the effects of sitagliptin analogue (SITA) or pioglitazone (PIO) treatment on glucose homeostasis and Β-cell dynamics in animal models of type 2 diabetes--Akita and db/db mice were evaluated. After 4-6 weeks of treatment, both SITA and PIO were shown to lower non-fasting glucose levels and reduced glycemic excursion in the intraperitoneal glucose tolerance test. In addition, both drugs preserved normal islet structure and the proportion of Β-cells in the islets. Compared to the controls, SITA treatment induced a higher Β-cell proliferation rate in Akita mice and a lower rate of apoptosis in db/db mice, whereas PIO treatment induced a lower rate of apoptosis in db/db mice and reduced proliferation rates in Akita mice. In conclusion, both SITA and PIO appear to exert some beneficial effects on the islet structure in addition to glycemic control via different mechanisms that involve Β-cell dynamics in Akita and db/db mice. [BMB reports 2011; 44(11): 713-718].     

Proteomic analysis of tumor tissue in CT-26 implanted BALB/C mouse after treatment with ascorbic acid

Tumor establishment and penetration consists of a series of complex processes involving multiple changes in gene expression and protein modification. Proteome changes of tumor tissue were investigated after intraperitoneal administration of a high concentration of ascorbic acid in BALB/C mice implanted with CT-26 cancer cells using two-dimensional gel electrophoresis and mass spectrometry. Eighteen protein spots were identified whose expression was different between control and ascorbic acid treatment groups. In particular, eukaryotic translation initiation factor 3 subunit 1, nucleophosmin, latexin, actin-related protein 2/3 complex subunit 5, M2-type pyruvate kinase, vimentin, tumor protein translationally-controlled 1, RAS oncogene family Ran, plastin 3 precursor, ATPase, Rho GDT dissociation inhibitor β, and proteasome activator subunit 2 expression were quantitatively up-regulated. The increase in the level of these proteins was accompanied by an increase in mRNA level. The cytoskeleton protein actin, vimentin, and tumor protein translationally-controlled 1 showed quantitative expression profile differences. A change in actin cytoskeleton distribution, functionally relevant to the proteome result, was observed after treatment with ascorbic acid. These results suggest a previously undefined role of ascorbic acid in the regulation of cytoskeleton remodeling in tumor tissues.     

Characterization of a β-glucosidase from Sulfolobus solfataricus for isoflavone glycosides

The specific activity of a recombinant β-glucosidase from Sulfolobus solfataricus for isoflavones was: daidzin > glycitin > genistin > malonyl genistin > malonyl daidzin > malonyl glycitin. The hydrolytic activity of this enzyme for daidzin was highest at pH 5.5 and 90°C with a half-life of 18 h, a K _m of 0.5 mM, and a k _cat of 2532 s⁻¹. The enzyme converted 1 mM daidzin to 1 mM daidzein after 1 h with a molar yield of 100% and a productivity of 1 mM h⁻¹. Among β-glucosidases, that from S. solfataricus β had the highest thermostability, k _cat, k _cat/K _m, conversion yield, and productivity in the hydrolysis of daidzin.     

Biochemical characterization of ferredoxin-NADP(+) reductase interaction with flavodoxin in Pseudomonas putida

Flavodoxin (Fld) has been demonstrated to bind to ferredoxin- NADP(+) reductase A (FprA) in Pseudomonas putida. Two residues (Phe(256), Lys(259)) of FprA are likely to be important for interacting with Fld based on homology modeling. Sitedirected mutagenesis and pH-dependent enzyme kinetics were performed to further examine the role of these residues. The catalytic efficiencies of FprA-Ala(259) and FprA-Asp(259) proteins were two-fold lower than those of the wild-type FprA. Homology modeling also strongly suggested that these two residues are important for electron transfer. Thermodynamic properties such as entropy, enthalpy, and heat capacity changes of FprA-Ala(259) and FprA-Asp(259) were examined by isothermal titration calorimetry. We demonstrated, for the first time, that Phe(256) and Lys(259) are critical residues for the interaction between FprA and Fld. Van der Waals interactions and hydrogen bonding were also more important than ionic interactions for forming the FprA-Fld complex. [BMB Reports 2012; 45(8): 476-481].     

Seasonal changes in nitrogen-cycle gene abundances and in bacterial communities in acidic forest soils

The abundance of genes related to the nitrogen biogeochemical cycle and the microbial community in forest soils (bacteria, archaea, fungi) were quantitatively analyzed via real-time PCR using 11 sets of specific primers amplifying nifH, bacterial amoA, archaeal amoA, narG, nirS, nirK, norB, nosZ, bacterial 16S rRNA gene, archaeal 16S rRNA gene, and the ITS sequence of fungi. Soils were sampled from Bukhan Mountain from September of 2010 to July of 2011 (7 times). Bacteria were the predominant microbial community in all samples. However, the abundance of archaeal amoA was greater than bacterial amoA throughout the year. The abundances of nifH, nirS, nirK, and norB genes changed in a similar pattern, while narG and nosZ appeared in sensitive to the environmental changes. Clone libraries of bacterial 16S rRNA genes were constructed from summer and winter soil samples and these revealed that Acidobacteria was the most predominant phylum in acidic forest soil environments in both samples. Although a specific correlation of environmental factor and gene abundance was not verified by principle component analysis, our data suggested that the combination of biological, physical, and chemical characteristics of forest soils created distinct conditions favoring the nitrogen biogeochemical cycle and that bacterial communities in undisturbed acidic forest soils were quite stable during seasonal change.     

Biological characterization of epigallocatechin gallate complex with different steviol glucosides

Steviol glucosides (SGs) such as rubusoside (Ru), stevioside (Ste), rebaudioside A (RebA) and stevioside glucosides (SG) are herbal tea sweeteners that enhance the solubility and stability of a number of pharmaceutically important compounds. The complex of epigallocatechin gallate (EGCG) with 10% (w/v) each Ru, Ste, RebA or SG enhanced the water solubility of EGCG over 15 times to 345, 312, 341, or 320 mg/mL, respectively. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging (SC₅₀) activities of EGCG, EGCG-Ru, EGCG-Ste, EGCG-RebA, and EGCG-SG in water were 5.88, 6.03, 6.52, 4.89, and 4.23 μg/mL, respectively. EGCGs complexed with different SGs maintained inhibitory activities against human intestinal maltase, human pancreatic α-amylase, and the growth of Streptococcus mutans, Helicobacter pylori, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, and Clostridium difficile. In glucose tolerance test using C57BL/6 mice, plasma glucose levels in mice treated with EGCG or EGCG-Ste complex were decreased by 9.34%, which was 31.08% lower than those treated with maltose. The efficient and cost-effective EGCG-SGs production method might be applicable to produce water soluble bioactive nutraceuticals in large scale.     

RraAS1 inhibits the ribonucleolytic activity of RNase ES by interacting with its catalytic domain in <Emphasis Type="Italic">Streptomyces coelicolor</Emphasis>

RraA is a protein inhibitor of RNase E, which degrades and processes numerous RNAs in Escherichia coli. Streptomyces coelicolor also contains homologs of RNase E and RraA, RNase ES and RraAS1/RraAS2, respectively. Here, we report that, unlike other RraA homologs, RraAS1 directly interacts with the catalytic domain of RNase ES to exert its inhibitory effect. We further show that rraAS1 gene deletion in S. coelicolor results in a higher growth rate and increased production of actinorhodin and undecylprodigiosin, compared with the wild-type strain, suggesting that RraAS1-mediated regulation of RNase ES activity contributes to modulating the cellular physiology of S. coelicolor.     

2-D DIGE and MS/MS analysis of protein serum expression in rats housed in concrete and clay cages in winter

In a previous study, we examined the physiological responses of male Sprague-Dawley rats over a 4-week exposure to concrete and clay cages. No general toxicological changes were observed in rats exposed to either of the two cage types in summer. Under winter conditions, however, various general toxicological effects were detected in rats housed in concrete cages, although rats housed in clay cages showed no such effects. The infrared thermographic examination indicated that skin temperature in the concrete-housed rats was abnormally low, but not so in the clay-housed rats. We examined proteomic changes in the serum of rats housed in winter in concrete and clay cages using two-dimensional differential in-gel electrophoresis and mass spectrometry/mass spectrometry. Five proteins were identified and quantitatively validated; all were cold stress-induced, acute phase proteins that were either up-regulated (haptoglobin) or down-regulated (alpha-1-inhibitor III, alpha-2u globulin, complement component 3, and vitamin D-binding protein) in the concrete-housed rats. These results suggest that the 4-week exposure to a concrete cage in winter elicited a typical systemic inflammatory reaction (i.e. acute phase response) in the exposed rats.