Electrochemical and Spectroscopic Studies on Interaction between Complex of Copper(Ⅱ) with Schiff Base Ligand and DNA

The crystal structure of ( [CuL (H2O) 2 ] (ClO4) 2 · 2H2O, CuL) (L ＝ N- (5-sulfosalicylidene)-4' -bromoaniline) was determined by means of X-ray crystallography. The interaction between CuL and salmon sperm DNA in a 0. 1 mol/L HOAc-NaOAc buffer solution (pH 5.10) was investigated by cyclic voltammetry and UV-Vis spectroscopy. A couple of redox peaks of CuL in the cyclic voltammograms(CV) can be seen at the glassy carbon electrode. It was found that the peak current of CuL decreased significantly with a negative shift of the peak potential in the presence of DNA compared with that in the absence of DNA. In addition,the decreased absorbance of CuL was observed with increasing the concentration of DNA; the absorption spectrum of an ethidium bromide(EB)-DNA system inthe presence of CuL confirms that the binding mode of CuL to DNA is different from the intercalation of EB with DNA. All the experimental results indicate that CuL can bind to DNA by electrostatic binding and form a 1:1 association complex with a binding constant of 2.72×104 L/mol.     

8-羟基喹啉-山梨酸稀土配合物与鲱鱼精DNA相互作用的光谱研究

合成了以山梨酸(SA)和8-羟基喹啉(Hq)为配体的Sm(Ⅲ)、Eu(Ⅲ)为中心的三元稀土配合物,研究了配合物与DNA之间的作用机制。采用红外光谱、紫外-可见吸收光谱、差热热重、元素分析和摩尔电导等方法,确定了配合物的化学组成,采用光谱法探讨了配合物与鲱鱼精DNA的作用机制。结果表明:配合物的化学组成为Sm(Hq)(SA)2和Eu(Hq)(SA)2,其最大吸收峰在加入DNA后发生减色和红移,中性红(NR)使配合物-DNA体系的吸收发生减色,伴有等色点出现。配合物的加入导致NR-DNA体系的吸收峰强度和位置发生变化。计算求得Eu(Hq)(SA)2和Sm(Hq)(SA)2分别与DNA的结合位点数为5,在20℃下,Sm(Hq)(SA)2、Eu(Hq)(SA)2与DNA的结合常数分别是2.04×104L/mol和1.09×104L/mol。2种稀土配合物都能不同程度地猝灭NR-DNA体系的荧光,表明2种稀土配合物对DNA都有较强的嵌插作用且能自发进行,结合能力为Sm(Hq)(SA)2Eu(Hq)(SA)2。     

三聚氰胺与鯡鱼精DNA相互作用研究

采用UV、荧光光谱、电化学和粘度法等方法研究了三聚氰胺(MM)与鲱鱼精DNA的作用机制, 并采用凝胶电泳考察了MM对pBR322质粒DNA迁移作用的影响. 当pH为7.0时, 动力学参数的计算结果表明: 加入DNA前后MM电荷转移系数α分别为0.27和0.26, 速率常数k_s分别为5.58 s^-1和5.65 s^－1; 热力学研究表明MM与DNA的结合常数K约为10⁵ mol^－1•L, MM与DNA可能是以沟槽式相结合.     

水温对棘胸蛙人工孵化的影响

利用地下水微流水状态下孵化石蛙卵子,初步试验结果表明：水温对石蛙卵子的出苗率影响很大,21－23℃是其最适宜的孵化水温,当水温高于25℃,石蛙卵子开始出现畸形苗,32℃是其孵化的致死水温。     

乙酸对DNA空间结构微观损伤的Raman光谱特征

利用Raman光谱技术从分子水平研究了乙酸对鲱鱼精DNA空间结构微观损伤的特征。实验结果表明,鲱鱼精DNA被乙酸浸润处理后,Raman特征频率与强度均发生了不同程度的变化。证明了乙酸对DNA的损伤是整个分子,包括骨架磷酸基团、脱氧核糖及碱基。不仅是DNA的构象,而且其构型也发生了变化：氢键断裂,B型构象被修改,DNA单、双链断裂,碱基也受到了严重损伤。其碱基损伤严重程度依次为胞嘧啶、胸腺嘧啶、鸟嘌呤和腺膘呤。     

Magnetic Micromotors for Multiple Motile Sperm Cells Capture,Transport, and Enzymatic Release

An integrated system combining a magnetically‐driven micromotor and a synthetized protein‐based hyaluronic acid (HA) microflake is presented for the in situ selection and transport of multiple motile sperm cells (ca. 50). The system appeals for targeted sperm delivery in the reproductive system to assist fertilization or to deliver drugs. The binding mechanism between the HA microflake and sperm relies on the interactions between HA and the corresponding sperm HA receptors. Once sperm are captured within the HA microflake, the assembly is trapped and transported by a magnetically‐driven helical microcarrier. The trapping of the sperm‐microflake occurs by a local vortex induced by the microcarrier during rotation‐translation under a rotating magnetic field. After transport, the microflake is enzymatically hydrolyzed by local proteases, allowing sperm to escape and finally reach the target location. This cargo‐delivery system represents a new concept to transport not only multiple motile sperm but also other actively moving biological cargoes.     

DNA纤维热变性过程的差示扫描量热分析

鲱精ＤＮＡ纤维的差示扫描量热（ＤＳＣ）谱中，除存在一个高温区的变性峰以外，还有３个低温区的吸热峰，类似于蛋白质ＤＳＣ分析中出现的“变性前峰”。经过２５３１５Ｋ（－２０℃）冻结处理的ＤＮＡ纤维，空间结构稳定性提高，变性前峰峰温增加４～８Ｋ。冻结与非冻结两类样品中，变性前峰的焓值分别为－１０２５３和－７７６５ｋＪ·ｍｏｌ－１。作者探讨了ＤＮＡ变性前峰的成因，并认为ＤＮＡ变性过程中的多元性可能与碱基序列特异性有关。     

Titanium dioxide as an adsorbent to enhance the detection ability of near-infrared diffuse reflectance spectroscopy

A method for quantitative determination of fish sperm deoxyribonucleic acid(fsDNA) was developed by using titanium dioxide(TiO2) as an adsorbent and near-infrared diffuse reflectance spectroscopy(NIRDRS). The selective enrichment of fsDNA was proved by comparing the adsorption efficiency of bovine serum albumin, tyrosine and tryptophan, and the low adsorption background of TiO2 was illustrated by comparing the spectra of four commonly-used inorganic adsorbents(alkaline aluminium oxide, neutral aluminium oxide, nano-hydroxyapatite and silica). The spectral feature of fsDNA can be clearly observed in the spectrum of the sample. Partial least squares(PLS) model was built for quantitative determination of fsDNA using 28 solutions, and 13 solutions with interferences were used for validation of the model. The results showed that the correlation coefficient(R) between the predicted and the reference concentration is 0.9727 and the recoveries of the validation samples are in the range of98.2%–100.7%     

Study on the Interaction between Distamycin Analogs and DNA from Herring Sperm by Fluorimetry

Distamycin is a naturally occurring antibiotic which binds to the AT rich regions in minor groove of DNA1. We have reported the interaction between the analogs and calf thymus DNA by circular dichroism spectropolarimetry (CD) and isothermal titration calorimetry (ITC)2. Due to the greater sensitivity of fluorescence-based techniques in comparison with CD, we employ the fluorimety to explore the interaction between four new distamycin analogs and DNA from herring sperm. O2NNNOHNNO…     

Effects of exposure to dibutyltin dichloride on sperm density,viability and morphology in male mice

Experiments on the effects of 0.025–0.40 µg of dibutyltin dichloride (DBTCl) per kilogram body weight (kg bw), on sperm density, viability and morphology in mature mice were conducted by daily intraperitoneal injection for 7 days at 22 ± 2 °C and 12 h light–dark cycle conditions. The results demonstrated that DBTCl exhibited strong toxicity on sperm quality. Dosed with ≥ 0.05 µg DBTCl/kg bw groups, the testes weight, sperm density and the rate of survival of sperm decreased, whereas the rate of sperm abnormalities increased significantly. In addition, treatment with 0.05 µg DBTCl/kg bw resulted in increasing rate of sperm head abnormalities, whereas administration at 0.20 and 0.40 µg DBTCl/kg bw significantly increased the rate of sperm tail abnormalities. In the group treated at ≥ 0.10 µg DBTCl/kg bw, the mice body weights decreased. It appeared there was a noticeable dose–response relationship between DBTCl and the parameters studied. ED₅₀ values (7 days) of DBTCl for survival rate of sperm and density were 0.17 µg/kg bw and 0.19 µg/kg bw respectively. The present study provides a possibility for early diagnostic indicators and methods for sperm quality induced by organotin compounds (DBTCl) in mammals. Copyright © 2001 John Wiley & Sons, Ltd.