Cloning, expression, and bioinformatics analysis of heavy metal resistance-related genes fd-I and fd-II from Acidithiobacillus ferrooxidans.

Five heavy metals were introduced into the bacterial heavy metal resistance tests. The results showed that apparent inhibition effects of Cd2+ and Cu2+ on the growth of Acidithiobacillus ferrooxidans BYSW1 occurred at high concentrations (>0.04 mol l-1). Significant differences (P < 0.001) were both noticed in the expression of two ferredoxin-encoding genes (fd-I and fd-II) related to heavy metal resistance in the presence of Cd2+ and Cu2+ . When exposed to 0.06 mol l-1 Cd2+, the relative expression levels of fd-I and fd-II were about 11 and 13 times as much as those of the control, respectively. Similarly, exposure to 0.04 mol l-1 Cu2+ caused approximate 8 and 4 times higher than those of the control, respectively. These two genes were cloned and expressed in Escherichia coli, and the structures, functions of two corresponding target proteins, i.e. Ferredoxin-I (Fd-I) and Ferredoxin-II (Fd-II), were predicted. The recombinant cells inserted by fd-I or fd-II were more resistant to Cd2+ and Cu2+ compared with wild-type cells. This study was the first investigation regarding the contribution of fd-I and fd-II to enhancing heavy metal resistance of this bioleaching bacterium, and laid a foundation for further elucidation of heavy metal resistance mechanisms caused by Fd.

Cloning, Expression, and Bioinformatics Analysis of Heavy Metal Resistance Gene afe_1862 from Acidithiobacillus ferrooxidans L1 in Escherichia coli.

Molecular studies of copper and cadmium resistances in acidophilic bacteria are significant in biomining. In this study, afe_1862, which encodes a heavy metal-binding protein in Acidithiobacillus ferrooxidans L1, was amplified using PCR, cloned into the pET32a plasmid, and sequenced. Following SDS-PAGE analysis, optimization of the expression conditions and heterologous overexpression of afe_1862 in Escherichia coli BL21 in the presence of Cu2+ and Cd2+ were studied as well. The results indicated that AFE_1862 has higher resistance to Cu2+ than Cd2+. Bioinformatics analysis illustrated that AFE_1862 has a conserved HMA domain containing heavy metal-binding sites, which may play a role in transporting or detoxifying heavy metals.

Rotenone induces nephrotoxicity in rats: oxidative damage and apoptosis.

Previous studies have examined rotenone toxicity on the human central nervous system, especially in the pathogenesis of Parkinson's disease, but few have investigated the effects of rotenone on the kidney. Here, rotenone-induced nephrotoxicity was evaluated by determining morphological, biochemical, oxidative stress-related, and apoptotic factor alterations in rat renal tissue. Morphological and biochemical analyzes showed that rotenone administration to rats damaged renal tissue. Western blot results revealed that rotenone-induced oxidative damage, causing overproduction of glutathione, malonaldehyde, and reactive oxygen species (ROS), and inhibiting superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. Rotenone also decreased the mitochondrial membrane potential and increased voltage-dependent anion channel (VDAC), caspase-3, and caspase-9 protein levels, indicating an association of apoptosis with renal damage. Our results suggest that glutathione, malonaldehyde, and ROS may be signals of rotenone-induced oxidative damage, and that the mitochondrial pathway plays a key role in apoptosis of renal cells following rotenone administration.

Effect of Frankincense Extract on Nerve Recovery in the Rat Sciatic Nerve Damage Model.

This study investigated the effect of frankincense extract on peripheral nerve regeneration in a crush injury rat model. Forty-eight Sprague-Dawley rats were randomly divided into four groups: control and frankincense extract low-, medium-, and high-dose groups. At days 7, 14, 21, and 28 following the surgery, nerve regeneration and functional recovery were evaluated using the sciatic functional index (SFI), expression of GAP-43, and the proliferation of Schwann cells (SCs) in vivo and in vitro. At day 7, the SFI in the frankincense extract high-dose group was significantly improved compared with the control group. After day 14, SFI was significantly improved in the medium- and high-dose groups. There was no significant difference in GAP-43 expression among the groups at day 7. However, after day 14, expression of GAP-43 in the high-dose group was higher than that in the control group. Histological evaluation showed that the injured nerve of frankincense extract high-dose group recovered better than the other groups 28 days after surgery. Further, S100 immunohistochemical staining, MTT colorimetry, and flow cytometry assays all showed that frankincense extract could promote the proliferation of SCs. In conclusion, frankincense extract is able to promote sciatic nerve regeneration and improve the function of a crushed sciatic nerve. This study provides a new direction for the repair of peripheral nerve injury.