RNA聚合酶σ38亚基缺失对假单胞菌抗生物质合成代谢的影响

设计引物从假单胞菌M18基因组DNA中扩增并获得rpoS基因的378bp保守区段。以此为探针,从假单胞菌基因组文库中克隆了包括rpoS基因全序列及其相邻序列的3.1kb EcoRⅠ_XhoⅠ片段。通过抗性基因（抗庆大霉素基因）的定点插入构建了σ38亚基缺失突变株M18S。HPLC检测结果显示,σ38亚基缺失引起该菌株的抗生物质合成代谢的显著变化。与野生株相比,缺失突变株的吩嗪_1_羧酸在PPM和KMB中2种培养基中合成量由58μg/mL和10.2μg/mL分别减少到20.4μg/mL和0μg/mL;而缺失突变株的藤黄绿脓菌素则相反,在PPM和KMB两种培养基中合成量由0.5μg/mL和20.5μg/mL分别提高到75.4μg/mL和185.6μg/mL。表明σ38亚基可区别性调控假单胞菌M18的抗生物质合成代谢。rpoS基因的互补实验和两种抗生素基因与β_半乳糖苷酶基因的翻译融合表达实验进一步验证了上述的结果: σ38亚基正调控吩嗪_1_羧酸的表达,而负调控藤黄绿脓菌素的表达。     

胡萝卜及其愈伤组织细胞质Ca~(2 )水平分析的研究

为测定植物细胞质内[Ca~(2 )]_i,对胡萝卜(Daucus carota var.sativa DC.)原生质体制备介质做了改进,并在正常生理条件下,用温和的、非损伤性的方法将Ca~(2 )荧光指示剂indo-1 K~ 和fura-2 K~ 导入该原生质体,能很好地标记细胞质内的游离Ca~(2 )。在此基础上,用显微荧光光度单波法测定被标记原生质体单个细胞胞质[Ca~(2 )]_i。结果表明:被indo-1 K~ 标记的胡萝卜及其愈伤组织的原生质体[Ca~(2 )]_i分别为88.3nmol/L和263.0nmol/L;fura-2 K~ 标记的分别为99.9nmol/L和255.5nmol/L。由此可见,脱分化的、处在细胞周期中的愈伤组织细胞质中[Ca~(2 )]_i远高于分化了的、处于静息态的胡萝卜细胞。此外,为了确认测量的可靠性,对两种Ca~(2 )荧光指示剂分别做了体外校正,证明其线性相关。     

亲代与杂种一代间方差不等时杂种优势的统计检验

近似服从标准正态分布。但当样本容量n_1、n_2及n_3较小时,(4)式也不能应用,本文旨在讨论当σ_1~2≠σ_2~2≠σ_3~2、且样本容量n_1、n_2及n_3较小时,杂种优势H_(ij)的统计检验。至于条件σ_1~2=σ_2~2=σ_3~2是否成立,可用Bartlett X~2检验法检验之。     

血管紧张素Ⅱ增加新生鼠脑细胞胞浆Ca~(2+)浓度

本文应用荧光钙测定技术观察了血管紧张素Ⅱ(AⅡ)对新生Wistar鼠脑细胞胞浆Ca~(2+)浓度([Ca~(2+)]_i)的影响。结果表明:血管紧张素Ⅱ在1nmol/L—1μmol/L浓度下可诱导新生鼠脑细胞[Ca~(2+)]_i增加,具量效关系。在无外Ca~(2+)存在对,其增加幅度有所减少。上述效应可被血管紧张素Ⅱ拮抗剂Saralasin所阻断,并呈剂量依赖关系。上述结果提示,血管紧张素Ⅱ可激活血管紧张素AⅡ受体,增加脑细胞[Ca~(2+)]_i,该效应通过细胞内Ca~(2+)释放和细胞外Ca~(2+)内流两条适径实现,前者的作用是主要的。     

猫海马注射去甲肾上腺素对血浆皮质醇浓度的影响

本工作报道了在戊巴比妥钠麻醉猫的海马不同区域注射去甲肾上腺素(NE)时血浆皮质醇浓度的变化及其作用受体。腹侧海马(VHIP)注入NE(4 μg/2μl),血浆皮质醇浓度明显升高,在背侧海马(DHIP)注入NE,则此作用不大。进一步分析表明,注射β受体阻断剂心得安(10μg/2μl),对皮质醇升高效应无明显影响,但此效应可被α受体阻断剂酚妥拉明(10μg/2μl)、α_1受体阻断剂哌唑嗪(2μg/2μl)或α_2受体阻断剂育亨宾(4μg/2μl)所阻断。这些结果表明,VHIP的α受体对于调节血浆皮质醇浓度起着较大的作用。     

RNA聚合酶σ^38亚基缺失对假单胞菌抗生物质合成代谢的影响

设计引物从假单胞菌M18基因组DNA中扩增并获得rpoS基因的378bp保守区段。以此为探针,从假单胞菌基因组文库中克隆了包括rpoS基因全序列及其相邻序列的3·1kbEcoRⅠ-XhoⅠ片段。通过抗性基因(抗庆大霉素基因)的定点插入构建了σ38亚基缺失突变株M18S。HPLC检测结果显示,σ38亚基缺失引起该菌株的抗生物质合成代谢的显著变化。与野生株相比,缺失突变株的吩嗪-1-羧酸在PPM和KMB中2种培养基中合成量由58μg/mL和10·2μg/mL分别减少到20·4μg/mL和0μg/mL;而缺失突变株的藤黄绿脓菌素则相反,在PPM和KMB两种培养基中合成量由0·5μg/mL和20·5μg/mL分别提高到75·4μg/mL和185·6μg/mL。表明σ38亚基可区别性调控假单胞菌M18的抗生物质合成代谢。rpoS基因的互补实验和两种抗生素基因与β-半乳糖苷酶基因的翻译融合表达实验进一步验证了上述的结果:σ38亚基正调控吩嗪-1-羧酸的表达,而负调控藤黄绿脓菌素的表达。     

内向整流钾通道阻滞剂BaCl_2引起大鼠冠状动脉收缩的机制

为了探讨内向整流钾通道(inward rectifier K~+channels,K_(ir))阻滞剂BaCl_2引起大鼠冠状动脉(rat coronary artery,RCA)收缩的作用机制,本研究采用离体微血管环张力记录法观察BaCl_2引起的RCA收缩对细胞内Ca~(2+)([Ca~(2+)]_i)释放和细胞外Ca~(2+)([Ca~(2+)]_o)内流的依赖性,并通过抑制剂实验探讨其作用机制。结果显示,静息状态下,BaCl_2(0.1~1.0 mmol/L)浓度依赖性地收缩离体RCA,最大收缩幅度为(5.69±1.07)m N,与KCl(60 mmol/L)收缩幅度相近;BaCl_2在无钙液中所引起的收缩占其总收缩的(35.44±6.72)%,复钙进一步引起(64.56±5.94)%的收缩;钙通道阻滞剂硝苯地平(0.3μmol/L)、环氧合酶抑制剂吲哚美辛(100μmol/L)、细胞外信号调节激酶ERK1/2抑制剂PD98059(10μmol/L)和氯通道阻滞剂尼氟灭酸(100μmol/L)分别使BaCl_2引起的RCA最大收缩幅度降低(87.82±5.43)%(P0.01)、(73.23±5.47)%(P0.01)、(75.69±7.94)%(P0.01)和(83.24±7.69)%(P0.01)。上述实验结果表明,BaCl_2引起RCA收缩依赖于[Ca~(2+)]_i释放和[Ca~(2+)]_o内流,并提示该过程与增加前列腺素类物质合成、钙通道和氯通道激活及ERK1/2通路有关。     

靶向探针追踪Aβ_(25-35)的亚细胞定位并基于Nrf2通路探讨阿里红多糖对线粒体损伤的保护机制

用靶向探针追踪淀粉样蛋白(Aβ_(25-35))的亚细胞定位情况,同时基于Nrf2信号通路探讨阿里红多糖组分(FOAPs-a)和(FOAPs-b)对Aβ_(25-35)诱导的PC12细胞线粒体损伤通路的保护作用机制。采用40μmol/L Aβ_(25-35)诱导PC12细胞建立阿尔茨海默病(AD)细胞模型,将PC12细胞分为空白组、模型组(加40μmol/L Aβ_(25-35))、阳性组(加50μmol/L盐酸多奈哌齐)、不同浓度的FOAPs-a和FOAPs-b干预组(各50、100、200μg/mL)。以靶向探针追踪Aβ_(25-35)在各组PC12细胞中的亚细胞定位情况;通过试剂盒检测PC12细胞中活性氧自由基ROS的变化情况;Western blotting法测定细胞凋亡相关蛋白Bax及Bcl-2的表达量以及和Nrf2通路相关的Nrf2、APK1和磷酸化的APK1蛋白的表达情况。结果发现,Aβ_(25-35)处理PC12细胞会影响线粒体的完整性;在200μg/mL FOAPs-a/b预处理PC12细胞后,能够显著缓解Aβ_(25-35)对线粒体的损伤,同时使Aβ_(25-35)的亚细胞共定位减弱;与空白组比较,模型组细胞中ROS含量增加,与模型组比较,FOAPs-a及FOAPs-b干预组均能降低ROS的沉积,差异有统计学意义;Western blotting结果显示:与模型组比较FOAPs-a及FOAPs-b均能减少APK1的磷酸化水平,上调Nrf2的蛋白表达水平。总之Aβ_(25-35)可进入到PC12细胞的线粒体中引起其损伤,阿里红多糖组分能够通过激活Nrf2信号通路显著缓解Aβ_(25-35)对PC12细胞线粒体的损伤。     

中枢α受体在大鼠颈动脉窦反射中的调制作用

孤离大鼠左侧颈动脉窦,采用侧脑室(LCV)注射α_1受体阻断剂酚苄明(phenoxybenzam-ine PBZ,2μg/20μl)或α_2受体阻断剂育亨宾(yohimbine Y,2μg/20μl),以颈动脉窦内压(ISP)-平均动脉压(MAP)关系曲线及其有关参数为指标,研究和分析了中枢α受体对颈动脉窦反射的影响。将所得ISP和MAP经Logistic方程拟合,建立ISP-MAP关系曲线。结果如下:PBZ组,ISP-MAP关系曲线在高窦内压区明显上移;峰斜率、MAP变动范围明显减小;ISP-斜率关系曲线在15.96kPa处明显下移。Y组,ISP-MAP关系曲线在高窦内压区明显上移;峰斜率、MAP变动范围明显减小,阈压明显增大,ISP-斜率关系曲线在10.64、15.96kPa处明显下移。与PBZ组相比,Y组的峰斜率、MAP变动范围减小更明显。结果表明:中枢α_1或α_2受体阻断后,窦反射的敏感性明显降低,其中阻断α_2受体的作用尤为明显。     

我国十省(市)十字花科蔬菜芜菁花叶病毒(TuMV)株系分化研究 Ⅰ.用Green氏方法划分株系

Provvidenti,R.(1980)和Green,S.K.(1985)先后用同一套鉴别寄主谱,研究了美国和我国台湾省的TuMV株系分化情况。本文用Green的方法,对由十省(市)7,982份病样中筛选出的19个TuMV主流分离物,在同一条件下进行了鉴定。结果表明,属于C_1株系的有黑_3分离物;属于C_4株系的有京_2、京_3、冀_2、宁_1(南京)、粤_1和川_1共6个分离物;属于C_5株系的有黑_1、辽_1、京_1、冀_1、沪_1、鲁_1、鲁_2共7个分离物。未检出C_2和C_3株系。黑_2、沪_2、宁_2和秦_1(陕西)共4个性状相近的分离物和冀_3分离物尚不能按Green的标准归类,暂分别定为C_(3-2)和C_6株系。此外,对Green氏方法应用于我国十字花科蔬菜TuMV株系分化研究中存在的问题作了讨论。     

Comparative kinetics of the early repair of intestines and lung in mice after fast neutron and gamma-ray irradiation

Early repair (Elkind) after d(50) + Be neutron and gamma irradiation is assessed by determining the additional dose Dr necessary to reach a given biological effect when a single fraction Ds is split into 2 equal fractions 2Di separated by a time interval "i". LD50 at 180 days after thoracic irradiation is used as an evaluation of late pulmonary tolerance; LD50 at 5 days after abdominal irradiation is used as an evaluation of early intestinal tolerance. Dr is reduced but still important after neutron irradiation as compared to gamma irradiation. For LD50/180, after fast neutron irradiation Dr reaches 66, 90, 64, 162, 195, 150 cGy for "i" = 1, 2, 3, 5, 4, 12, and 24 hours respectively; after gamma irradiation, Field and Hornsey reported Dr = 390, 530, and 376 cGy for "i" = 2, 6, and 24 hours respectively; after neutron irradiation, they reported Dr = 190 cGy for "i" = 24 hours. For LD50/5, after fast neutron irradiation, Dr = 14, 45, 43, and 133 cGy for "i" = 1,5, 3,5, 5,5 and 24 hours respectively. Early repair is faster after gamma irradiation: Dr reaches a maximum for "i" = 3-4 hours. For neutrons, Dr reaches its maximum at 24 hours for both criteria.     

Spin probe mobility in the whole blood of white rats]

By means of ESR-method the rotary mobility of a tanol spin probe is studied in the whole blood of white rats at the temperatures 5.20 and 37 degrees C. It is shown that at all the temperatures the spin probe is localized in the blood plasma and has a value HFS a = (17.1 +/- 0.1) G. By means of linear anamorphism method it is shown on the example of the spectrum central line that the contour is lorenz, i. e. the superposition of the spectra of different sample regions is absent. The spin probe rotation frequency v is a stable blood parameter, the same for 11 rats investigated and dependent only on the blood temperature. For T = 5.20 and 37 degrees C the values have been received v = (86 +/- 2) x 10(8) s-1, (98 +/- 2) x 10(8) s-1 and (107 +/- 3) x 10(8) s-1, subsequently, which compared to v value in water-glycerin system (1:1) (WGS) allow one to calculate the blood microviscosity values (7.2 +/- 0.4), (6.3 +/- 0.4) and (5.8 +/- 0.4) mPds, subsequently. For the mentioned temperatures the non-sphericity parameter epsilon of the spin probe rotation has the values 0.19 +/- 0.03, 0.22 +/- 0.04 and 0.21 +/- 0.05, subsequently that is close to this parameter value for WCS (epsilon = 0.21 +/- 0.02; v = (6 divided by 20) x 10(9) s-1).     

Sequestration of biogenic amines by alginic and fulvic acids

The interaction of natural (alginic and fulvic acids) and synthetic (polyacrylic acid 2.0 kDa) polyelectrolytes with some protonated polyamines [diamines: ethylendiamine, 1,4-diaminobutane (or putrescine), 1,5-diaminopentane (or cadaverine); triamines: N-(3-aminopropyl)-1,4-diaminobutane (or spermidine), diethylenetriamine; tetramine: N,N'-bis(3-aminopropyl)-1,4-diaminobutane (or spermine); pentamine: tetraethylene-pentamine; hexamine: pentaethylenehexamine] was studied at T=25 degrees C by potentiometry and calorimetry. Measurements were performed without supporting electrolyte, in order to avoid interference, and results were reported at I=0 mol L(-)(1). For all the systems, the formation of (am)L(2)H(i) species was found (am=amine; L=polyelectrolyte; i=1...4, depending on the amine considered). The stability of polyanion-polyammonium cation complexes is always significant, and for high-charged polycations, we observe a stability comparable to that of strong metal complexes. For example, by considering the formation reaction (am)H(i)+2L=(am)L(2)H(i) we found log K(i)=6.0, 6.5 and 10.8 for i=1, 2 and 3, respectively, in the system alginate-spermidine. Low and positive formation DeltaH(degrees) values indicate that the main contribution to the stability is entropic in nature. The sequestering ability of polyelectrolytes toward amines was modelled by a sigmoid Boltzman type equation. Some empirical relationships between stability, charges and DeltaG(degrees) and TDeltaS(degrees) are reported. Mean values per salt bridge of formation thermodynamic parameters (DeltaX(degrees) (n)) are DeltaG(degrees) (n)=-5.8+/-0.4, DeltaH degrees (n)=0.7+/-0.5 and TDeltaS(degrees) (n)=6.5+/-0.5 kJmol(-)(1) for all the systems studied in this work.     

分支分类学中和谐性概念与和谐性分析方法

和谐性是分支分类学中的一个基本概念。本文给出一个和谐性的数学定义,称为Kexue和谐性。并在Kexue和谐性的基础上开发出一个新的和谐性分析方法。并对该方法在分支分类研究中的应用进行讨论。     

昆虫学百分率差异显著性统计分析的简易计算方法

昆虫学定量分析资料常有2类不同性质的百分率,即组成的百分率和独立的百分率。在进行差异显著性检验时,如果样本数n较大,则组成百分率可用标准正态变量μ检验。作者给出一个简便的计算公式:μ=n0.5|P1-P2|,其中ni,nj分别为第i,j组的频次数。如果只有2组,则μ=n0.5|P1-P2|,其中P1,P2分别为第1,2组的频次数。对独立的百分率进行F检验时,如果多数数据在30%～70%之外,则应通过反正弦变换使百分率变换为角度。这种变换的实际效果往往使差异显著性提高。     

Kinetics of bicarbonate transport in human red blood cell membranes at body temperature

We studied unidirectional [14C]HCO3- efflux from human resealed red cell ghosts with 1 mM acetazolamide under self-exchange conditions at pH = pH(i = o) 7.4-9.0 and 0-38 degrees C by means of the Millipore- Swinnex and continuous flow tube filtering techniques. 14CO2 loss from cells to efflux medium and further to the atmosphere was insignificant. [14C]HCO3- efflux was determined at pH 7.8, 38 degrees C under symmetric variation of the HCO3- concentrations (C(i = o)), and asymmetric conditions: C(i) varied, C(o) constant, or C(o) varied, C(i) constant. MM-fit, Jeff = Jmaxeff x C x (C + K1/2)-1, used to describe the concentration dependence of Jeff,o when only C(o) varied, yields at C(i) = 50 mM: K1/2o = 3.8 mMJ, Jmaxeff.o = 20 nmol cm-2 s-1; at C(i) = 165 mM: K1/2o = 10 mM, Jmaxeff.o = 32 nmol cm-2 s-1. When C(i) varied, noncompetitive self inhibition by HCO3- binding (inhibitor constant K1) to an intracellular site was included (MS-fit). Under conditions of (a) symmetry: C(i = o) = 9-600 mM, K1/2s = 173 mM, K1 = 172 mM, and Jmaxeff,s = 120 nmol cm-2 s-1, (b) asymmetry: C(o) = 50 mM, K1/2i = 116 mM, K1 = 136 mM, and Jmaxeff,i = 92 nmol cm-2 s-1. All flux parameters accord with the ping-pong model for anion exchange. The data for C(i) < 200 mM also fit well to the MM equation, but K1/2 and Jmaxeff are different from the MS-fit and are inconsistent with the ping-pong model. Thus, self-inhibition (MS-fit) must be included even at low concentrations. As at 0 degree C, the system is asymmetric: 8-10 times more unloaded transport sites face inward than outward when C(i = o). Jeff,s was not mono-exponentially dependent on temperature at 0-38 degrees C, indicating that the transmembrane anion transport is controlled by several rate constants with different temperature dependencies. Jeff,s was not significantly affected by increasing pH(i = o) from 7.4 to 7.8, but it decreased by 50% when pH was raised to 9.0.     

Speciation of phytate ion in aqueous solution. Sequestration of magnesium and calcium by phytate at different temperatures and ionic strengths, in NaCl(aq)

The formation and stability of Mg(2+) and Ca(2+)-phytate complexes was studied potentiometrically using an ISE-H(+) electrode. Measurements were performed at 10 degrees C and 25 degrees C in NaCl(aq) in the ionic strength range 0.1< or =I< or =0.75 mol L(-1). For both magnesium and calcium systems, the formation of ten M(i)PhyH(j)((12-2i-j)-) species was observed in the range 3< or =pH< or =7 with i=1, 2, 3 and j=3, 4, 5 (and i=3, j=2). These species are quite stable; here we report for example some quantitative data for the species Ca(i)PhyH(3)((9-2i)-), i=1, 2, 3 (equilibrium iCa(2+)+H(j)Phy((12-j)-)=Ca(i)PhyH(j)((12-j-2i)-): K(ij)) at I=0.25 mol L(-1) and t=25 degrees C: logK(13)=3.42, logK(23)=6.47 and logK(33)=9.41. The speciation of the Ca(2+)-phytate system was also checked by ISE-Ca(2+) measurements. Dependence on ionic strength was modeled using a simple Debye-Hückel type equation and formation constants were calculated at infinite dilution. The stability constants of complexes formed at pH>7 were estimated using an empirical predictive equation. The sequestering ability of phytate towards Mg(2+) and Ca(2+) was calculated in different experimental conditions and compared with those of other chelating agents.     

Karyotypes of 5 species of Soricidae-Crocidura in the fauna of the USSR

The chromosomes of five Crocidura species have been studied by means of routine, G-, C- and Ag NOR-banding techniques. The karyotypes of the species with 2n = 40, i.e. C. gueldenstaedtii, C. suaveolens and C. sibirica, are identical. Short arms of the Y-chromosome of C. sibirica are larger. The karyotypes of C. leucodon (2n = 28) and C. zarudnyi (2n = 22) could be obtained as a result of tandem and centric fusion and pericentric inversions. Small amounts of heterochromatin were detected in autosomes of the species investigated. The Y-chromosomes are completely heterochromatic. Four NOR-bearing pairs are detected in the species investigated.     

Intelligence and educational level in adult males at the extremes of stature

Stature and intellectual ability are commonly found to correlate positively (r approximately 0.2). In this study we have assessed whether this relationship holds true at the extremes of stature in adults. From a representative study population of 76,111 young Danish men, we defined an extremely short group as those below the 2d percentile (less than or equal to 163 cm) and an extremely tall group as those above the 98th percentile (greater than or equal to 191 cm). The short group had intelligence test scores and educational levels lying at approximately two-thirds of a standard deviation below the overall means. The tall group had means lying approximately one-half standard deviation above the overall means. These deviations are to a large degree in agreement with the observed overall correlations of height with intelligence test scores (r = 0.244) and with educational level (r = 0.264). Both groups, however, appear to score somewhat below the levels expected from a purely linear relationship. For the short group there appear to be local factors that are particularly detrimental to intellectual ability. For the tall group corresponding local factors are relatively independent of intellectual ability.     

Formation and morphology of struvite and newberyite in aqueous solutions at 25 and 37 degrees C

The influence of the initial reactant concentrations (c(i)(Mg)tot = 5.0 x 10(6) to 5.0 x 10(-1) mol dm(-3), c(i)(P)tot = c(i)(NH4)tot = 1.0 x 10(-3) to 5.0 x 10(-1) mol dm(-3)) and temperature (25 and 37 degrees C) on the composition and morphology of the precipitates formed in the system MgCl2-NH4H2PO4-NaOH-H2O at initial pHi = 7.40 has been investigated. Precipitation diagrams are presented showing the concentration regions within which different morphologies of solid phase have been formed. The solid phases aged for 24 hours were characterized by means of optical microscopy, FT-IR spectrophotometry, X-ray diffractometry and thermogravimetry. It was found that struvite was a predominant phase formed within the concentration region examined and newberyite was obtained only in the region where pH(24h) < 6.5. The influence of the initial pH on the formation and transformation of these two compounds were studied in the region 5.0 < or = pHi < or = 9.0 and the results are discussed.