Tris-(2,3-dibromopropyl) isocyanurate (TBC) is a heterocyclic brominated flame retardant that was recently detected in the environment in China.TBC is semi-volatile and can accumulate in the lipid of some species,but little is known about its effect on aquatic organisms.We exposed adult zebrafish to 0,0.25,1 and 4mg/L TBC for 28 d and measured the effect on survival,growth,histopathology,hormone levels,enzyme activity,and gene expression.TBC exposure had no effect on survival or growth.We observed significant damage to the liver and gill,including hepatocellular swelling and fatty degeneration in the liver as well as proliferation and edema of epithelial cells in the gills.In addition,exposure to 4mg/L TBC induced proliferation of goblet cells in the intestine of both sexes,acellular areas in the testis,and thinly scattered vitellogenic granules in vitellogenic oocytes.TBC exposure had no effect on the levels of thyroid hormones,testosterone,estradiol,liver superoxide dismutase activity,malondialdehyde content,and brain cholinesterase activity.By contrast,hepatic vitellogenin and cytochrome P4501A gene expression was significantly down-regulated in both male and female zebrafish in response to TBC exposure.Our results suggest that exposure to TBC causes a variety of potential reproductive and endocrine toxic effects.
Gold nanoparticles(AuNPs)have been reported to induce faster heat transfer of polymerase chain reaction(PCR)solution to enhance PCR efficiency.AuNPs can also increase the specificity of PCR by functioning analogously to single-stranded DNA binding protein(SSB).However,the simple structure of AuNPs makes it difficult to determine how AuNPs affect PCR efficiency and specificity.This study aimed to elucidate the effect of AuNPs on PCR efficiency by altering the denaturation times and annealing temperatures.In addition,comparative study of the effect of AuNPs on PCR inhibition caused by two competitive primers allowed investigation of the mechanisms of AuNP-enhanced PCR accuracy.Finally,heat-treated salmon sperm DNA was used to evaluate whether AuNPs could eliminate the inhibitory PCR effect caused by DNA impurities.This study demonstrated that enhanced thermal conductivity by AuNPs was the main mechanism for increased PCR efficiency and specificity.AuNPs promoted efficient double-stranded DNA template unwinding and dissociation between mismatched primers,DNA fragments and template,and enhanced PCR efficiency and specificity simultaneously.Thus,this significant finding suggests the future use of AuNP-assisted PCR in different fields,especially in rapid clinical diagnosis and screening by PCR.
LIN YanLI JiaYAO JingLIANG YongZHANG JieZHOU QunFangJIANG GuiBin
This study shows that C_(60) can degrade pBR322 plasmid DNA at room temperature without photoactivation. The degradation was enhanced by increasing incubation temperature, reaction time or C_(60) concentration. We also found that superoxide radical anions (O 2 · ) were formed in the C_(60) solution. Superoxide dismutase significantly inhibited DNA cleavage and O 2 · generation induced by C_(60) . These results suggest that DNA cleavage was caused by the formation of reactive oxygen species induced by C_(60) at room temperature. Furthermore, we demonstrate that the DNA degradation was significantly inhibited by acid amide chemicals such as formamide, and by increased ionic strength of the reaction solution. These results indicate that the DNA conformation stability and the surface properties of C_(60) are important factors regulating DNA degradation. We propose that C_(60) can bind DNA, decrease DNA conformation stability, and induce the formation of reactive oxygen species and DNA cleavage at room temperature. Our results provide a possible explanation for the genotoxicity of C_(60) , which should be considered in future use of this particular nano-material.
WANG ChangLIN YanWANG YingLIANG YongMENG LingZhiZHANG JieZHOU QunFangJIANG GuiBin