Cloning and transcription analysis of the nitrate reductase gene from Haematococcus pluvialis.

OBJECTIVES: To optimize the cultivation media for the growth rate of Haematococcus pluvialis and to study the transcription regulation of the algal nitrate reductase (NR), a key enzyme for nitrogen metabolism. RESULTS: The NR gene from H. pluvialis hd7 consists of 5636 nucleotides, including 14 introns. The cDNA ORF is 2718 bp, encoding a 905 aa protein with three conserved domains. The NR amino acids of H. pluvialis hd7 are hydrophilic and have similarity of 72% compared to that of Dunaliella. NR transcription increased with an increase of nitrate concentration from 0.4 to 1 g/l. A deficiency of nitrogen increased NR transcription significantly. The transcription level of NR increased at phosphorus concentrations from 0.08 to 0.2 g/l, with a maximum at 0.08 g/l. The optimum parameters of medium component for transcription of NR and growth of H. pluvialis were 0.3 g NaNO3/l, 0.045 g KH2PO4/l and 1.08 g sodium acetate/l. CONCLUSIONS: This study provides a better understanding of nitrate regulation in H. pluvialis.

N-octyl-N-Arginine chitosan micelles as an oral delivery system of insulin.

N-octyl-N-Arginine chitosan (OACS) was synthesized in an attempt to combine the permeation enhancing effects of arginine-rich peptides and the drug loading capacity of the amphipathic polymers for insulin oral delivery. OACS self-assembled micelles of insulin were prepared by the conventional stirring technique, which were characterized by Dynamic light scattering, transmission electron microscopy and differential scanning calorimetry. Molecular docking by Discovery studio software confirmed that the interactions between OACS and insulin were mostly electrostatic in nature. In vitro, the result of the degradation experiment by enzyme showed that the OACS has a relative protective effect for insulin from proteolyses. Compared to the insulin solution, OACS micelles increased the Caco-2 cell's internalization by up to 22.3 folds. In vivo, the pharmacological activity PA% of series OACS-insulin micelles ranged from 7.7%-16.8%. Meanwhile by increasing arginine degree of the substitution both the uptake in Caco-2 cells and the hypoglycemic effect in diabetic rats were enhanced. Therefore, it is concluded that using arginine polymeric micelles for the enhancement of oral insulin delivery is a promising approach for the oral peptide delivery.

A biomimetic chitosan derivates: preparation, characterization and transdermal enhancement studies of N-arginine chitosan.

A novel arginine-rich chitosan (CS) derivates mimicked cell penetration peptides; N-Arginine chitosan (N-Arg-CS) was prepared by two reaction methods involving activated L-arginine and the amine group on the chitosan. FTIR spectra showed that arginine was chemically coupled with CS. Elemental analysis estimated that the degrees of substitution (DS) of arginine in CS were 6%, 31.3% and 61.5%, respectively. The drug adefovir was chosen as model and its permeation flux across excised mice skin was investigated using a Franz diffusion cell. The results showed that the most effective enhancer was 2% (w/v) concentration of 10 kDa N-Arg-CS with 6% DS. At neutral pH, the cumulative amount of adefovir permeated after 12 hours was 2.63 ± 0.19 mg cm(-2) which was 5.83-fold more than adefovir aqueous solution. Meanwhile N-Arg-CS was 1.83, 2.22, and 2.45 times more effective than Azone, eucalyptus and peppermint, respectively. The obtained results suggest that N-Arg-CS could be a promising transdermal enhancer.

[Effects of inhibiting RhoA by Stealth RNA on high glucose-induced RhoA/ROCK signaling pathway in human mesangial cells].

OBJECTIVE: To observe the effect of small interference RNA (Stealth RNAiTM siRNA) of RhoA on the inflammatory response and fibrosis in human mesangial cell (HMC) and explore the role of RhoA/ROCK signaling pathway in the process of diabetic nephropathy. METHODS: Synchronized HMC were divided into several groups. Lipofectamine(TM)2000 was employed to transfect RhoA-siRNA and RhoA-negative siRNA into the above cells. RhoA-siRNA could inhibit the expression of RhoA. The expressions of RhoA, ROCK-I, fibronectin (FN), connective tissue growth factor (CTGF) and tumor necrosis factor-alpha (TNF-α) were detected by real-time reverse transcription-polymerase chain reaction (RT-PCR) and ELISA (enzyme-linked immunosorbent assay). RESULTS: (1) The expressions of RhoA, ROCK-I and CTGF mRNA were inhibited by RhoA siRNA transfection in high glucose-induced HMC. The expression of each mRNA was reduced 26% - 60% as compared with the high glucose-induced group (P < 0.05); (2) After RhoA siRNA transfection and culturing with high glucose for 48 h, FN, the secretions of CTGF and TNF-α significantly declined [FN: (1.99 ± 0.04) mg/L vs. (4.31 ± 0.13) mg/L, CTGF:(4.98 ± 0.17) mg/L vs. (6.06 ± 0.09) mg/L; TNF-α: (61.17 ± 2.59) ng/L vs.(91.76 ± 2.27) ng/L, all P < 0.05]. The levels of FN and CTGF almost decreased to those of normal glucose-induced HMC. CONCLUSION: The levels of FN, CTGF and TNF-α in high glucose-induced HMC may be lowered by inhibiting RhoA through RNA interference and reducing the accumulation of extracellular matrix, glomerular fibrosis and inflammation. Thus it provides a new intervention target for the prevention of diabetic nephropathy.