尼罗尖吻鲈和鳜鱼染色体组型分析及比较

采用PHA、秋水仙碱腹腔或背部肌肉注射,活体培养法,以前肾为材料,低渗-空气干燥法制片,进行染色体观察,运用Micromeasure version 3.3染色体分析软件和Photoshop 7.0软件首次分析了尼罗尖吻鲈的染色体数目和核型,并同鳜鱼染色体数目和核型进行了分析比较,对今后拟采取的杂交尝试提供理论基础。结果显示：尼罗尖吻鲈染色体众数为2n=48,核型公式为2m+4sm+12st+30t,染色体臂数（NF）为54;鳜鱼染色体众数为2n=48,核型公式为6sm+12st+30t,染色体臂数（NF）亦为54;两种鱼染色体短臂上均无随体,单臂染色体较多。分析表明尼罗尖吻鲈与鳜鱼杂交成功的可能性较大。     

两种国产苏铁属植物的核型分析

报道了苏铁属（Cycas L.）2种植物的染色体数目及其核型.它们的体细胞染色体数目均为2n=2x=22,核型均属3B型.核型公式分别是：海南苏铁C.hainanensis K（2n）=2x=22=4m＋2sm＋4st＋12T,仙湖苏铁C.szechuanensis subsp.fairylakea K（2n）=2x=22=2m＋4sm＋4st＋12T.两种苏铁的核型均为首次报道.支持基于染色体资料把苏铁属分为两个类群的观点.     

新疆裸重唇鱼染色体的核型及C-带研究初报

探索新疆裸重唇鱼的染色体数目和核型,并对新疆裸重唇鱼染色体进行C带型的描述和分析,填补领域内对这一物种研究的空白,为后续的研究打下基础。采用PHA体内注射肾细胞直接制片法研究新疆裸重唇鱼的核型,采用改进的BSG法来研究其C-带。结果表明,新疆裸重唇鱼的核型公式为2n=98=28m＋30sm＋12st＋28t,臂数NF=156。m1、sm1、sm2、t1和t2明显比同组其他染色体大,未发现小染色体及其他异型性染色体。C-带较丰富显示出3种类型的C-带,所有染色体都有着丝粒带,部分有端粒带,有些染色体两端都有端粒带,有些只有一端有端粒带,sm5、sm12和t 3还显示深浅不一的居间带。并通过与同亚科种类进行对比分析,讨论它们的亲缘关系和系统演化。     

杂交鳢(斑鳢 ♀ ×乌鳢 ♂ )及其自交后代细胞核型初步分析

对杂交鳢(斑鳢♀×乌鳢♂)(Channa maculata ♀×C.argus ♂)及其自交后代的细胞核型进行了初步分析.结果表明,杂交鳢染色体数目为2n=45,核型公式为3m+4sm+6st+32t,染色体臂数(NF)为52;杂交鳢自繁后代群体存在两种染色体核型,一是染色体数目为45,核型公式为3m+4sm+6st+...     

毛茛属五种植物的核型

对中国云南毛茛属（Ranunculus）5种植物核型进行研究,结果表明,毛茛组茴茴蒜（Ranunculus chinensis Bunge）和禺毛茛（R．cantoniensis DC．）核型公式为2n=2x=16=6m＋4sm＋6st和2n=4x=32：14m＋6sm＋12st;该组茴茴蒜、禺毛茛和扬子毛茛（R．sieboldii Miq．）的不同居群核型存在自西向东不对称系数渐增大现象。在美丽毛茛组中,深齿毛茛（R．pulchellusvar．stracheyanus Hand．-Mazz．）的中甸居群核型（2n=4x=32=12m＋12sin＋8st）与青海居群核型（2n：4x：32：24m＋8sm）明显不同;毛果高原毛茛（R．tangusticusvar．dasycarpus（Maxim．）L．Liou）染色体数目（2n=40）,核型公式（2n=5x=40=30m＋10sm）和纳帕海毛茛（R．napahaiensis W．T．Wang＆L．Liao）染色体数目（2n=40）,核型公式（2n=5x=40=20m＋16sin＋4st）为首次报道。     

三个家猪品种和rob易位群染色体分带多态性的比较

对家猪不同品种及家系间的染色体组型、C－带、Ag－NORs多态性进行的研究表明：杜洛克猪、约克夏猪、长白猪体细胞染色体数2n＝38,核型2n＝10sm＋12m＋4st＋12t,而13／17易位纳合子猪（36,rob．13／17）的体细胞染色体数2n＝36,核型2n＝10sm＋12m＋6st＋8t;13／17易位杂合子猪（37,rob．13／17）的体细胞染色体数目为2n＝37,核型为2n＝10sm＋12m＋5st＋10t。5种家猪的C－带在13～18号染色体上存在大、中、小三种类型,且呈多态性分布。杜洛克猪、约克夏猪、长白猪、13／17易位纳合子猪、13／17易位杂合子猪的Ag－NORs均数分别为2．05、2．062．00、1．99、1．98,说明Ag－NORs在品种、个体及细胞间具有多态性.     

木兰科3个杂交组合及其亲本的核型研究

研究了木兰科（Magaoliaceae）3个杂交组合的亲本和杂交后代的核型。结果表明,云南含笑（Michelia yunnanensis）、灰岩含笑（Michelia calcicola）及其杂交组合A的核型分别为2n=2x=38=36m＋2sm、2n=2x=38=34m＋4sm和2n=2x=38=26m＋12sm;紫花含笑（Michelia crassipes）及其与云南含笑杂交组合C的核型分别为2n=2x=38=32m＋6sm和2n=2x=38=24m＋12sm＋2st;山玉兰（Mognolia delavayi）、广玉兰（Mognolia grondiflora）及其杂交组合U的核型分别为2n=2x=38=28m＋10sm、2n=6x=114=88m＋lOsm＋16st和2n=4x=76=57m＋15sm＋4st。杂交组合的核型与理论核型存在明显的差异,可能是在杂交组合的形成过程中,来自亲本的染色体发生了结构变异。     

狗獾（Meles meles）的染色体研究

本文报告了狗獾北方亚种(Melesmeles leptorhynchus)的核型及染色体带型的研究结果。染色体数目2n=44,NF=72,常染色体分为4组(8m+12sm+10st+12t),X是一条中等大小的亚中着丝粒染色体,Y是一条最小的末端着丝粒染色体。并对染色体的G带、C带、Ag带带型作了详细描述和讨论。     

7种橐吾属植物的核型

研究了7种橐吾属（Ligularia）植物的染色体和核形态。干崖子橐吾（L．kanaitzensis）的核型为2n＝2x＝58＝26m＋28sm 4st;窄头橐吾（L.stenocephala）的核型为2n=2x=58=26m 32sm;细茎橐吾（L.hookeri）的核型为2n=2x=58=30m 26sm 2st;宽戟橐吾（Llatihastata）的核型为2n=2x=58=28m 26sm(2sat) 4st;网脉橐吾（L.dictyoneura）的核型为2n=2x=58=26m 28sm 2st 2t;蹄橐吾（L.hodgsonii）的核型为2n=2x=58=28m 28sm 2t;棉毛橐吾（L.vellerea）的核型为2n=2x=58=22cm 34sm 2t。虽然这7个种的染色体数目相同,2n=58,核型主要是由m和sm染色体构成,但各类的染色体数目在种间有差异。核的对称性高,着丝点端值（T．C）为61．45％－64．96％。除窄头橐吾和鹿蹄橐吾的染色体数与前人报道的相同外,其它5个种的染色体数目和核型为首次报道。     

5种桤木属植物的核型分析

利用改良去壁低渗法对桦木科（Betulaceae）桤木属（Ainus Mill.）东亚地区5种植物进行染色体数目与核型研究。结果显示：所试验物种中染色体形态比较一致,多是由中部（m）及近中部（sm）着丝点染色体组成。其中A.nitida染色体数为2n=28,核型公式为K（2n）=28=22m 4sm(2SAT) 2st(2SAT);A.hirsuta染色体数为2n=42,核型公式为K(2n)=42=36m 6sm; A.cremastogyne,A.formosana 染色体数均为2n=56,核型公式分别为K(2n)=56=2M 40m(1SAT) 14sm(1SAT)和K(2n)=56=46m 8sm 2st;A.firma染色体数为2n=112,核型公式为K(2n)=112=80m 28sm 4st。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.