Effects of nicotine on expression of nicotinic acetylcholine receptors in several kinds of stem cells

AIM To detect the subunits of nicotinic acetylcholine receptors (nAChRs) in stem cells and the changes of the receptors after nicotine treatment. METHODS Human embryonic stem cell line H9 and human induced pluripotent stem cells (IPSC) were cultured without feeder layer cells. Human umbilical cord mesenchymal stem cells (UCMSC) and human bone marrow mesenchymal stem cells (BMMSC) were also selected. Total RNA and protein were extracted from 4 kinds of cells after subculture, and total RNA was extracted after nicotine treatment. The mRNA and protein expression levels of the subunits of nAChRs were determined by RT-PCR, RT-qPCR and Western blot, and the expression location of the receptors was observed by cellular immunofluorescence. RESULTS The results of RT-PCR and Western blot showed that α2, α3, α4, α7, α9 and β1 subunits of nAChRs were detected in H9 cells, IPSC and UCMSC, while only α4, α7, α9 and β1 were expressed in BMMSC. After nicotine treatment, RT-qPCR results showed that α2 was significantly down-regulated in H9 and UCMSC but up-regulated in IPSC, while β2 was significantly up-regulated in BMMSC and IPSC but down-regulated in UCMSC. CONCLUSION The subunits of nAChRs expressed in embryonic stem cells and adult stem cells are different, and with the higher differentiation potential, the cells express the more types of subunits. The regulatory effect of nicotine on nAChR subunit expression in various stem cells is different, and H9 cells show high sensitivity to the effect of nicotine.     

流感病毒受体在三种动物气管和肺脏分布的组织化学检测

利用凝集素组织化学染色的方法,对岭南黄鸡、番鸭和BALB/C小鼠的气管和肺脏进行了流感病毒受体分布的检测。结果表明:在岭南黄鸡、番鸭和小鼠的气管粘膜层、粘膜下层、肺脏的细支气管和肺泡上皮细胞均有禽流感病毒受体的分布。番鸭和小鼠气管和肺脏的人流感病毒受体的分布范围和细胞类型与禽流感病毒受体的分布稍有差异,岭南黄鸡气管和肺脏未检测到人流感病毒受体的分布。研究结果为探讨流感病毒的感染机制和宿主特异性的差异提供了基础数据。     

昆虫嗅觉相关蛋白及嗅觉识别机理研究概述

嗅觉是昆虫产生行为的基础之一,在长期进化的过程中昆虫形成了复杂的嗅觉系统,完成这一过程,需要有多种与嗅觉相关的蛋白参与,包括气味结合蛋白、化学感受蛋白、气味受体和感觉神经元膜蛋白等。了解昆虫感受外界信息的嗅觉机制可以帮助我们更好地理解昆虫识别配偶、天敌及寻找食物来源、产卵场地等行为特征,为进一步调控昆虫的行为、防控害虫侵袭、保护和利用有益昆虫奠定基础。本文综述了昆虫嗅觉相关的几类重要蛋白的生化特性和生理功能,并对昆虫气味分子的识别机制、气味分子在昆虫体内运输机制的最新研究进展进行了概述。     

仔猪产肠毒素大肠杆菌F4受体研究进展

猪肠毒素大肠杆菌F4(ETEC F4)是引起1～2周龄仔猪黄、白痢最普遍、危害最大的大肠杆菌。ETEC F4能否致病,决定于猪的小肠上皮细胞有无ETEC F4受体。本文综述了ETEC F4的黏附模式,F4特异受体在猪小肠中的分布,受体的生化特性,受体编码基因的定位、克隆现状及存在的问题,并对今后F4受体的研究方向及应用前景进行了展望。     

Specific binding of bovine, ovine, caprine and equine IgG subclasses to defined types of immunoglobulin receptors in gram-positive cocci

One hundred and twenty bacterial strains were tested for non-immune binding of radiolabelled bovine, ovine, caprine and equine immunoglobulins. Bacteria possessing previously defined IgG receptors interacted in a well defined manner with purified IgG subclass immunoglobulins. Human group C and G streptococci carrying IgG receptors type III were capable of binding all IgG subclasses in the four mammalian species studied. Protein A-containing staphylococci demonstrated a restricted specificity with binding of bovine IgG1, ovine IgG1, caprine IgG1 and IgG2 as well as equine IgG(ab). Group A streptococci which can bind human IgG did not show specific reactivity. A new type of binding unrelated to the regular Fc-mediated binding was observed with equine IgG(T).The differences in specificity for IgG subclasses suggest that structures with binding capacity to streptococcal type III Fc receptors are different from staphylococcal protein A reactive sites. Inhibition experiments performed with purified immunoglobulins showed that individual IgG subclasses differed greatly in their inhibiting capacity reflecting differences in avidity.The high avidity and the broad, unrestricted immunoglobulin G reactivity of streptococcal IgG receptor type III indicate that human group C and G streptococci may provide a valuable tool for solid phase absorption of immunoglobulins from several mammalian species.     

Production of Transgenic Anliucheng Sweet Orange （Citrus sinensis Osbeck） with Xa21 Gene for Potential Canker Resistance

Citrus canker, an epidemic quarantine disease caused by Xanthomonas axonopodis pv. citri, has brought a great damage in citrus production worldwide. Herein, a rice PRR （pattern recognition receptor） gene Xa21 together with GUS reporter gene and hygromycin phosphotransferase gene （HPT） was introduced into Anliucheng sweet orange （Citrus sinensis Osbeck） via Agrobacterium-mediated transformation of embryogenic callus. The transgenic calluses were screened on MT basal medium containing hygromycin （HYG） and detected by histochemical GUS staining. The transgenic plantlets were recovered through somatic embryogenesis pathway. The regenerated plantlets were accustomed to and maintained in the greenhouse. The transgene integration of recovered plantlets was identiifed by PCR and Southern blot hybridization. It showed that all the transgenic plantlets tested had undergone single copy integration, the expression of Xa21 in eight different transgenic lines detected by qRT-PCR can be divided into three grades, high for T5 and T6, middle for T4 and low for the rest. The tolerance to citrus canker disease of the three recovered transgenic lines T2, T4 and T6 was assessed by in vitro pin-puncture inoculation. The results showed that all the three transgenic lines conferred improved resistance to citrus canker bacterium infection and the T4 transgenic line displayed the highest resistance. The mechanism and feasibility of rice Xa21 in triggering innate immunity in citrus was brielfy discussed.     

半边莲生物碱抑制肾性高血压大鼠内皮素1mRNA和蛋白表达

目的观察半边莲生物碱对肾性高血压大鼠内皮素1 mRNA表达、蛋白合成和释放的影响。方法采用两肾一夹高血压大鼠模型,随机分为高血压组、半边莲组、卡托普利组和假手术组。用原位杂交技术观察大鼠外周血白细胞内皮素1 mRNA的表达,应用免疫组织化学染色计数大鼠主动脉内皮细胞铺片内皮素阳性细胞率(反映内皮素1蛋白的合成),用放射免疫技术测定大鼠血浆内皮素的含量。结果与假手术组比较,高血压组外周血白细胞内皮素1mRNA表达增强(34.64%±8.39%比9.34%±4.47%,P<0.05),动脉内皮细胞合成内皮素增多(7.42%±0.24%比1.58%±0.24%,P<0.05),血浆内皮素水平显著升高(221±24ng/L比138±19ng/L,P<0.05)。应用半边莲生物碱8周后,与高血压组比较,内皮素1 mRNA表达(20.38%±11.31%比34.64%±8.39%,P<0.05)、内皮素合成(3.53%±0.21%比7.42%±0.24%,P<0.05)和血浆内皮素水平(191±21ng/L比221±24ng/L,P<0.05)均受到显著抑制。结论肾性高血压大鼠伴有内皮素表达增强,半边莲生物碱能抑制内皮素基因的转录、蛋白合成及翻译,对防治肾性高血压所致的血管病变具有一定作用。     

The presence of 17α,20β-dihydroxy-4-pregnen-3-one receptor activity in the ovary of the brook trout,Salvelinus fontinalis,during terminal stages of oocyte maturation

The presence of 17,20-dihydroxy-4-pregnen-3-one (17,20-DHP) oocyte receptor activity has been demonstrated in brook troutSalvelinus fontinalis. Scatchard analyses of the cytosol fraction during various terminal stages of oocyte maturation gave a high equilibrium association constant (K_a) value of 1.394±0.669 10⁸M^–1 (n=7) and low maximum binding capacities (N_max). The association kinetics of the receptor was second order k₊₁=2.292×10⁶M^–1 sec^–1. The dissociation rate constant k_a was 1.502×10^–2 sec^–1 for the first order dissociation reaction. The K_a=1.526×10⁸M^–1, when it was determined from k₊₁/k_–1 a value close to that found from the Scatchard analysis. Competition studies showed the following binding affinities testosterone > 17-HP > 17,20-DHP > Promegestone > progesterone > estradiol > pregnenolone; cortisol showed no competitive inhibition. Cytosolic extracts when pre-equilibrated with various labelled steroids and eluted from a Sephacryl S-300 column gave multiple specific binding peaks. On sucrose density gradient centrifugation specific binding was observed at 3.05 S in cytosol containing 0.15M sodium chloride buffer. The receptor lost binding activity when incubated with various proteases, but DNase and RNase had no effect. Blood plasma without heparin at (110) dilution also bound [³H]17,20-DHP, Ka was 8.04×10⁷ M^–1.The nuclear pellet extract (750×g) gave very little specific binding activity even at high radiolabelled steroid concentrations and a linear Scatchard plot was not obtained. Nevertheless the nuclear extract, after dextran-charcoal treatment, pre-equilibrated with [³H]17,20-DHP, bound specifically to DNA cellulose, and cytosol from the same oocytes also bound to DNA cellulose under similar conditions. Although specific binding to DNA cellulose was obtained the salt concentrations at which the steroid-receptor complex elution took place was not reproducible in both nuclear extracts and cytosol samples. Also binding activity was extremely small compared to the total cytosolic binding. The nuclear extract when pre-equilibrated with high concentrations (20 nM) of the labelled steroid and then chromatographed on Sephacryl S-300 column gave a specific binding peak which was similar to that of the cytosolic preparation.The receptor levels in cytosol decreased progressively during final maturation (Stages 1–7). There is preliminary evidence for the presence of 17,20-DHP receptor activity in cytosol of landlocked Atlantic salmonSalmo salar ouananiche, and rainbow troutSalmo gairdneri. The zona radiata fraction from late stages oocyes 5, 6, and 7 in brook and rainbow trout oocytes were isolated by ultracentrifugation; from this fraction a protein was characterized which covalently bound [³H]R5020 after photoaffinity labelling. The same protein also bound [³H]17,20-DHP after solubilization in Brig 35 buffer. The SDS gel electrophoresis subunit composition of the above protein was similar to the cytosol counterpart binding [³H]17,20-DHP, although the molecular weights were different. The blood sample [³H]R5020 binding component subunit composition was different from that of the membrane extracted protein. These results demonstrate the presence of 17,20-DHP receptor activity in the cytosol and zona radiata membranes of the oocytes during final maturation.A. Maneckjee is presently NSERC postgraduate scholar at MSRL and Ph.D. candidate at Department of Biochemistry, Memorial University of Newfoundland.