Identification of Autotoxic Compounds in Fibrous Roots of Rehmannia (Rehmannia glutinosa Libosch.)

Rehmannia is a medicinal plant in China. Autotoxicity has been reported to be one of the major problems hindering the consecutive monoculture of Rehmannia. However, potential autotoxins produced by the fibrous roots are less known. In this study, the autotoxicity of these fibrous roots was investigated. Four groups of autotoxic compounds from the aqueous extracts of the fibrous roots were isolated and characterized. The ethyl acetate extracts of these water-soluble compounds were further analyzed and separated into five fractions. Among them, the most autotoxic fraction (Fr 3) was subjected to GC/MS analysis, resulting in 32 identified compounds. Based on literature, nine compounds were selected for testing their autotoxic effects on radicle growth. Seven out of the nine compounds were phenolic, which significantly reduced radicle growth in a concentration-dependent manner. The other two were aliphatic compounds that showed a moderate inhibition effect at three concentrations. Concentration of these compounds in soil samples was determined by HPLC. Furthermore, the autotoxic compounds were also found in the top soil of the commercially cultivated Rehmannia fields. It appears that a close link exists between the autotoxic effects on the seedlings and the compounds extracted from fibrous roots of Rehmannia

Gene transfection mediated by polyethyleneimine-polyethylene glycol nanocarrier prevents cisplatin-induced spiral ganglion cell damage

Polyethyleneimine-polyethylene glycol (PEI-PEG), a novel nanocarrier, has been used for transfection and gene therapy in a variety of cells. In our previous study, we successfully carried out PEI-PEG-mediated gene transfer in spiral ganglion cells. It remains unclear whether PEI-PEG could be used for gene therapy with X-linked inhibitor of apoptosis protein (XIAP) in the inner ear. In the present study, we performed PEI-PEG-mediated XIAP gene transfection in the cochlea of Sprague-Dawley rats, via scala tympani fenestration, before daily cisplatin injections. Auditory brainstem reflex tests demonstrated the protective effects of XIAP gene therapy on auditory function. Immunohistochemical staining revealed XIAP protein expression in the cytoplasm of cells in the spiral ganglion, the organ of Corti and the stria vascularis. Reverse transcription-PCR detected high levels of XIAP mRNA expression in the cochlea. The present findings suggest that PEI-PEG nanocarrier-mediated XIAP gene transfection results in XIAP expression in the cochlea, prevents damage to cochlear spiral ganglion cells, and protects hearing

Effects of heavy metal ions on seeds germination and radicle growth of Brassica napus

Heavy metals had different effects on seed germination and radicle growth.Toxicity of five types of heavy metal ions (Hg2+,Cd2+,Ni2+,Co2+ and Zn2+) on the initial growth of Brassica napus and whether the application of K+,Mg2+ and Ca2+ could alleviate the effects of heavy metals on the seeds germination and radicle growth of B.napus were investigated.The results showed that radicle growth was more sensitive to heavy metals than seed germination.Zn2+ was not very toxic to seed germination but was to radicle growth.Hg2+ was the most toxic metal for plant growth and development.K+ and Ca2+ slightly alleviated the toxicity of Ni2+,Zn2+ and Co2+ to seed germination,while slightly increased the toxicity of Hg2+ and Cd2+.Mg2+ was effective to reduce the toxicity of Ni2+,Zn2+,Cd2+ and Co2+ on seed germination,but was not influence to Hg2+.The toxicity of Ni2+,Hg2+,Cd2+ and Co2+ on radicle growth was partially enhanced in the present of 5 mmol/L K+ and Mg2+ while Ca2+ partially restored the inhibition of Zn2+,Ni2+ and Co2+.The researches are helpful for further research on elucidating fundamental mechanism of heavy metal tolerance and cultivating plants on heavy-metal-contaminated soil

Formation and elimination mechanisms of prior particle boundaries in a new powder metallurgy superalloy

The formation of prior particle boundaries (PPBs) in a new powder metallurgy superalloy during hot isostatic pressing (HIP) is investigated. Also, the impact of subsequent hot deformation on the elimination of PPBs is systematically studied. The PPBs involves large γ′ phases, carbides (MC and M6C) and oxides (Al2O3, SiO2 and ZrO2). The reactions among the superficial oxides, the adsorbed C and O elements on the particle surface and internally-migrated alloying elements are the dominant reasons for the formation of PPBs during HIP. Besides, the existence of surface tension and surface energy induces the carbon segregation, as well as the formation of PPBs. Thus, the density of PPBs decreases when the spacing between powders is shrunk by a rapid deformation. In hot forming process, the PPBs can be efficiently eliminated via raising deformation temperature/true strain or reducing strain rate. The interactions between dislocations and PPBs, as well as the occurrence of dynamic recrystallization (DRX) induced by the strain/orientation gradient, lead to the elimination of PPBs. The thermodynamic stability of carbides declines with the raised temperature. It indicates that the dissolution of carbides and the elimination of PPBs can be accelerated via raising the deformation temperature. The breakage or deformation behavior of PPBs during hot extrusion is investigated by numerical simulation. The deformation degree of PPBs increases with the raised extrusion ratio. The above important findings are useful for developing hot extrusion processing to effectively eliminate PPBs

The validity of Pelophylax chosenicus (Okada, 1931) and P. hubeiensis (Fei & Ye, 1982) (Amphibia, Ranidae)

Pelophylax plancyi (Lataste, 1880), Pelophylax chosenicus (Okada, 1931) and Pelophylax hubeiensis (Fei & Ye, 1982) were described chronologically from East Asia. The three species have similar morphological and molecular characteristics, but the taxonomic relationships amongst them have long been ambiguous. To deal with this taxonomic issue, we examined newly-obtained topotypic specimens of P. plancyi, P. chosenicus and P. hubeiensis for morphological comparison. Furthermore, we investigated the phylogeny of pond frogs in Eurasia by Bayesian Inference and Maximum Likelihood analyses of a fragment consisting of mitochondrial DNA gene 16s and provided a molecular phylogeny of the genus Pelophylax. There were no morphological and molecular differences between P. plancyi and P. chosenicus, but both morphological and molecular differences between P. hubeiensis and P. plancyi. Hence, we conclude that P. chosenicus is a junior synonym of P. plancyi and P. hubeiensis is a separate species from P. plancyi