Specific interactions in RNA enzyme-substrate complexes

Analysis of crosslinked complexes of M1 RNA, the catalytic RNA subunit of ribonuclease P from Escherichia coli, and transfer RNA precursor substrates has led to the identification of regions in the enzyme and in the substrate that are in close physical proximity to each other. The nucleotide in M1 RNA, residue C92, which participates in a crosslink with the substrate was deleted and the resulting mutant M1 RNA was shown to cleave substrates lacking the 3' terminal CCAUCA sequence at sites several nucleotides away from the normal site of cleavage. The presence or absence of the 3' terminal CCAUCA sequence in transfer RNA precursor substrates markedly affects the way in which these substrates interact with the catalytic RNA in the enzyme-substrate complex. The contacts between wild-type M1 RNA and its substrate are in a region that resembles part of the transfer RNA "E" (exit) site in 23S ribosomal RNA. These data demonstrate that in RNA's with very different cellular functions, there are domains with similar structural and functional properties and that there is a nucleotide in M1 RNA that affects the site of cleavage by the enzyme.     

乳酸钠对小鼠1—细胞胚胎体外发育的影响

小鼠 1-细胞胚胎在含10.8,16.2,21.6和32.4 mM 乳酸钠不同 Whitten's 液中培养时,分别有2.6%,172%,8.5%和0%的胚胎发育到扩展囊胚。在4种培养液中均有60%以上的胚胎完成了第1次卵裂,发育到2-细胞期,但以后的发育则有明显差异。培养液中较高浓度乳酸钠的存在,可能是造成小鼠胚胎体外培养的“2-细胞早期阻断”的原因之一。     

农杆菌介导薄皮甜瓜遗传转化体系建立

以薄皮甜瓜"M15"和"M43"子叶节为外植体,研究激素浓度、卡那霉素浓度和消毒时间等对甜瓜子叶节再生及农杆菌介导遗传转化的影响。结果表明,诱导甜瓜子叶节不定芽分化最佳激素组合为0.5 mg·L~(-1)6-BA+0.05 mg·L~(-1)IAA,芽伸长激素为0.05 mg·L~(-1)6-BA,生根激素为0.1 mg·L~(-1)IAA。农杆菌介导甜瓜转化最佳条件为预培养48 h,OD_(600)=0.6农杆菌菌液侵染15 min,黑暗条件下共培养48～72 h,头孢抑菌浓度500 mg·L~(-1),卡那霉素浓度75 mg·L~(-1)。PCR检测卡那霉素抗性苗,验证外源基因已整合进入甜瓜基因组,"M15"和"M43"抗性植株阳性率分别为84.2%和77.4%。     

EGF和GSH对牛卵母细胞体外受精的影响

研究了牛卵泡卵母细胞体外受精时向成熟液中加入EGF(表皮生长因子),受精液中加入GSH(谷胱甘肽)对受精率和囊胚率的影响。成熟液以M-199为基础液并加入一定浓度的促性腺激素和OCS,作为成熟液的对照组,试验组加入不同浓度的EGF。受精液以改良TALP为基础液并加入一定浓度的BSA、肝素和咖啡因,作为受精液的对照组,试验组加入不同浓度的GSH。早期胚胎培养液为SOFaa。在成熟液中加入10ng/mlEGF和50ng/mlEGF组时,试验组与对照组的受精率分别为76.00%(114/150)、76.71%(112/146)和60.70%(85/140);囊胚率分别为23.68%(27/114)、24.11%(27/112)和17.64%(15/85);在受精液中加入1mMGSH和10mMGSH组时,试验组与对照组的受精率分别为71.66%(86/120)、63.28%(81/128)和76.00%(114/150);囊胚率分别为34.88%(30/86)、24.69%(20/81)和23.68%(27/114)。结果表明,成熟液中加入EGF对牛卵母细胞的体外成熟和受精后的早期胚胎的发育都有促进作用,在一定范围内增加EGF浓度,不会提高受精率和囊胚率;受精液中加入一定浓度GSH能够提高受精率和囊胚率,但是在高浓度的GSH时则影响受精率。     

玻璃化冷冻对猪卵母细胞体外发育能力的影响

采用猪未成熟(GV期)和体外成熟(MⅡ期)卵母细胞分组进行冷冻保护剂毒性试验,试验组经冷冻液处理,对照组不用冷冻液处理。结果表明,GV期与MⅡ期卵母细胞相比,两者经冷冻保护剂处理后,其存活率、体外受精胚卵裂率均无显著差异(P>0.05);试验组GV期卵母细胞存活率、体外成熟率及体外受精胚卵裂率虽略低于对照组(85.9%,72.4%和50.9%对91.3%,73.9%和53.3%),但差异不显著(P>0.05);试验组MⅡ期卵母细胞存活率虽显著低于对照组,但卵裂率与对照组无显著差异(P>0.05)。表明所用冷冻液及其处理程序,对卵母细胞无明显毒性。分3组对猪卵母细胞进行冷冻保存试验:I组为对照组;II组为GV期卵母细胞冷冻组;III组为MⅡ期卵母细胞冷冻组。结果表明,经开放式拉管(Open pulled straw,OPS)法玻璃化冷冻后,GV期和MⅡ期卵母细胞均获得较高的形态正常率,但GV期卵母细胞冷冻后存活率要显著高于MⅡ期卵母细胞(P<0.05)。经玻璃化冷冻后,GV期卵母细胞的体外成熟率和卵裂率均明显低于新鲜卵母细胞(42.6%和7.79%对73.9%和53.3%,P<0.05),MⅡ期卵母细胞冷冻-解冻后未获得卵裂。在GV期卵母细胞冷冻组,154枚卵母细胞冷冻后经体外成熟、体外受精及体外培养,共有12枚发生卵裂,其中6枚发育至8-细胞,3枚发育至16-细胞,3枚发育至桑椹胚。本研究表明,所用冷冻方案更适合于猪GV期卵母细胞的冷冻保存。     

Alleviation of Al Toxicity in Barley by Addition of Calcium

The potential mechanism by which Ca alleviates Al toxicity was investigated in barley seedlings. It was found that 100 Al-alone treatment inhibited barley plant growth and thereby reduced shoot height and root length, and dry weights of root, shoot and leaf; promoted Al accumulation but inhibited Ca absorption in plant tissues; and induced an increase in the activities of superoxide dismutase （SOD）, catalase （CAT）, and peroxidase （POD） and in the level of lipid peroxidation （MDA content） in leaves. Except for the increase in Ca concentration in plant tissues, treatment with 0.5 mM Ca in the absence of Al had less effect on the above-mentioned parameters, compared with the control. Addition of Ca efficiently reduced Al toxicity, which is reflected by the promotion of plant growth, reduction in Al concentration and MDA content, increase in Ca concentration and in SOD, POD, and CAT activities compared with the Al-alone-treatment; with increase in Ca level （3.0 raM）, the ameliorative effect became more dominant. This indicated that the alleviation of aluminum toxicity in barley seedlings with Ca supplementation could be associated with less absorption of Al and the enhancement of the protective ability of the cell because of increased activity of the antioxidative enzyme.     

Reactivated triton-extracted models o paramecium: modification of ciliary movement by calcium ions

Triton-extracted models of Paramecium were reactivated to swim in solutions of adenosine triphosphate and magnesium ions. The cilia beat in the normal direction (toward the rear) when the calcium ion concentration was less than 10-(6)M, and they beat in the "reversed" direction (toward the front) when calcium ion concentration was raised above 10-(6)M. These results support the proposal that ciliary reversal, hence backward swimming, of live paramecia is mediated by an increased cytoplasmic calcium concentration around the ciliary system by calcium-dependent membrane responses to external stimuli.     

NaCl胁迫对不同品种番茄种子发芽特性的影响

本研究采用 6个番茄栽培品种,以不同浓度NaCl对种子发芽作盐胁迫处理。研究结果表明,在发芽期的耐盐力上,参试品种间存在明显差异。“豫番茄1号”和“圣女”耐盐力最强:在60mmol/L NaCl胁迫时,发芽才明显推迟;在80mmol/L NaCl胁迫时,相对发芽率还分别可达64.8％和56.9％。“洋杂94—1”耐盐力最弱:在20mmol/L NaCl胁迫时,发芽就明显推迟;在80mmol/L NaCl胁迫时,发芽率为零。     

降低烤烟烟碱含量化学物质的筛选

对现蕾期烟株施用不同的化学物质,并测定成熟烟叶的烟碱含量,发现叶面喷施50μM-αNAA、3μMGA3、1.25 mM乙烯利、1 mM CuSO4、1 mM ZnSO4以及根部浇灌100μM-αNAA可以显著降低腰叶和上二棚烟叶的烟碱含量;通过测定上述处理烤后烟叶的化学成分,以叶面喷施50μM-αNAA的处理化学成分符合优质烟叶的要求,烟叶可用性最高。     

Lactate dehydrogenase isozymes: further kinetic studies at high enzyme concentration

In the report "Lactate dehydrogenase isozymes: Further kinetic studies at high enzyme concentration" by Thomas Wuntsch, Raymond F. Chen, and Elliot S. Vesell [169, 480 (1970)], 14.0 mM NAD in line 2 of the heading of Table 1 should read 14.0 , microM NAD.     

赤松根际土壤微生物PCR—DGGE反应体系优化

为建立赤松根际土壤微生物的PCR-DGGE反应体系,以赤松根际土壤为材料,利用PCR—DGGE技术,对反应体系中的几个重要因素不同梯度进行优化,包括模板DNA、dNTPs、引物及Mg2＋的用量。在25μL PCR反应体系中,模板DNA浓度为10ng,dNTPs浓度为0．15mM,引物浓度为0．32μM,Mg2＋浓度为1．0mM时,其PCR效果最佳。用该反应体系扩增出来的PCR产物,在DGGE凝胶上能够清晰地分辨出赤松根际土壤细菌和真菌多样性。这为进一步研究赤松根际土壤微生物,特别是研究赤松外生菌根奠定了基础。     

Genotypic Difference in the Responses of Seedling Growth and Cd Toxicity in Rice (Oryza sativa L.)

The experiment was carried out to study the genotypic difference in the responses of seed germination, growth and physiological characters of rice seedlings to Cd toxicity. The result showed that the germination was slightly stimulated under low Cd concentration (0.01-1.5 mM Cd), while severely depressed under higher Cd concentration (2.0 mM). Rice seedlings exposed to 0.01 mM Cd showed slight increases in plant height, root volume, biomass and chlorophyll concentration. These parameters were significantly reduced when Cd level in the medium was increased to 0.5 mM, and meanwhile corresponding increase in superoxide dismutase (SOD) and peroxidase (POD) activities, and MDA (malondialdehyde) content was observed. However, SOD and POD activities declined when plants were exposed to 1 mM Cd when compared with those under 0.5 mM Cd. Cadmium addition lowered Fe, Cu and Mn concentrations in roots and shoots. There was significant genotypic difference in the response of these parameters to Cd stress. Under Cd stress, Xiushui 110 had the least inhibition of growth and increase in MDA content, higher shoot Cd concentration, and greatest increase in POD and SOD activities, indicating its higher tolerance to Cd toxicity, while Bing 9914 had the greatest reduction of growth, and Zn, Cu, Fe, and Mn contents, but greatest increase in MDA content, and least increase in activities of antioxidative enzymes, indicating its sensitivity to Cd toxicity.     

Genotypic Difference in the Responses of Seedling Growth and Cd Toxicity in Rice （Oryza sativa L.）

The experiment was carried out to study the genotypic difference in the responses of seed germination, growth and physiological characters of rice seedlings to Cd toxicity. The result showed that the germination was slightly stimulated under low Cd concentration （0.01-1.5 mM Cd）, while severely depressed under higher Cd concentration （2.0 mM）. Rice seedlings exposed to 0.01 mM Cd showed slight increases in plant height, root volume, biomass and chlorophyll concentration. These parameters were significantly reduced when Cd level in the medium was increased to 0.5 mM, and meanwhile corresponding increase in superoxide dismutase （SOD） and peroxidase （POD） activities, and MDA （malondialdehyde） content was observed. However, SOD and POD activities declined when plants were exposed to 1 mM Cd when compared with those under 0.5 mM Cd. Cadmium addition lowered Fe, Cu and Mn concentrations in roots and shoots. There was significant genotypic difference in the response of these parameters to Cd stress. Under Cd stress, Xiushui 110 had the least inhibition of growth and increase in MDA content, higher shoot Cd concentration, and greatest increase in POD and SOD activities, indicating its higher tolerance to Cd toxicity, while Bing 9914 had the greatest reduction of growth, and Zn, Cu, Fe, and Mn contents, but greatest increase in MDA content, and least increase in activities of antioxidative enzymes, indicating its sensitivity to Cd toxicity.     

颗粒细胞对山羊卵泡卵母细胞体外成熟和体外受精的影响

试验系统研究了颗粒细胞对山羊卵泡卵母细胞体外成熟和体外受精的影响。COCs、机械裸卵和自然裸卵的体外成熟率分别为68.3%、45.6%和6.1%,组间差异显著(P<0.05),卵裂率分别为41.5%、8.1%和0,差异显著(P<0.05)。对照组和15×104个/ml、150×104个/ml颗粒细胞组卵母细胞体外成熟率分别为65.9%、60.2%和64.6%,无显著差异(P>0.05),但均显著高于1 500×104个/ml(50.0%)和1.5×108个/ml(30.3%)颗粒细胞组(P<0.05)。颗粒细胞单层共培养系统卵母细胞成熟率为75.8%,显著高于150×104个/ml颗粒细胞条件培养液组(63.4%)和M199培养液组(66.7%)(P<0.05)。颗粒细胞单层共培养系卵裂率为50.0%,显著高于150×104个/ml条件培养液组(36.7%)和M199培养液组(38.2%)(P<0.05)。     

培养基中糖和氮对脱毒甘薯组培苗生长的影响

以脱毒甘薯的茎段为材料，研究培养基中不同糖种类、糖浓度、NH4^＋/NO3^-及总氮量对甘薯组培苗扩繁的影响．结果表明：在MS培养基添加蔗糖或白糖，NH4^＋/NO3^-含量为30／30（mM／mM），总氮量控制在30，60mM时对甘薯组培扩繁有利．考虑到培养基成本，脱毒甘薯培养基以MS＋食用白糖50g／L＋NH4^＋/NO3^-30／30（mM／mM）＋总氮量30mM最为适宜．将脱毒甘薯组培苗移栽到含蛭石和草炭的营养钵中进行驯化，成活率可达95％．     

谷氨酸对延边黄牛体细胞克隆重组胚发育的影响

为了提高延边黄牛体细胞克隆重组胚的发育率,试验研究了在培养液中添加一定浓度的谷氨酸对延边黄牛克隆重组胚发育的影响。选择成熟了20～22 h并且排出第一极体的卵母细胞进行去核与注核,然后进行体外培养,观察卵母细胞的卵裂以及囊胚发育情况。结果显示,低浓度的谷氨酸能够提高重组胚的卵裂率,高浓度则抑制卵母细胞的卵裂;而囊胚的发育方面,低浓度的谷氨酸会降低其发育率。所以,添加适量浓度的谷氨酸能够提高延边黄牛体细胞克隆重组胚的发育率。     

培养基种类对梨试管苗茎增殖的影响

培养基种类显著影响梨试管苗茎的增殖。外殖体在MS培养基上产生的茎,叶片大、叶色浓绿,平均茎长(2.9厘米)、鲜重(175毫克)和干重(26毫克)值最高,但平均茎数(2.9)最少。WPM产生的茎,叶片小、叶色黄绿,平均茎长(2.0厘米)、鲜重(67毫克)和干重(9.3毫克)值最低,但平均茎数(7.3)最多。QL培养基产生的茎,各项指标均介于MS和WPM之间。三种培养基的主要差异表现为:MS培养基的总离子浓度(94.22mM)和总氮浓度(60.01mM)最高,WPM最低,分别为42.51mM和14.70mM。QL介于两者之间(68.45mM和37.88mM)。上述差异表明,高总离子浓度或高氮浓度的培养基有利于梨外殖体已分化茎的生长,反之,则有利于茎的分化。     

几种因素对高山红景天愈伤组织诱导和增殖的影响

以高山红景天叶片为材料,研究了BA和NAA浓度对愈伤组织诱导的影响及MS培养基中氮和磷对愈伤组织增殖的影响。结果表明,在MS培养基中加入BA3mg／L和NAA0．3mg／L时高山红景天叶片愈伤组织的诱导效果好于其他BA和NAA浓度处理,诱导率达到62．2％。将诱导出的愈伤组织进行增殖培养时,将MS培养基中NH4＋／NO3-配比由原有的20／40mM调节为30／30mM,PO43-浓度为1．25mM时,愈伤组织增殖生长良好,增殖系数达16．3。     

甜菜碱对三黄鸡胚胎原代成纤维细胞生长和增殖的影响

【研究目的】研究了不同剂量甜菜碱对三黄鸡胚胎原代成纤维细胞微核和增殖的影响,在细胞水平上揭示甜菜碱对三黄鸡生长影响的机理,为甜菜碱在动物生产中的应用提供依据。【方法】体外分离培养三黄鸡胚胎成纤维细胞,在培养液中添加不同剂量甜菜碱,观察细胞生长及分裂。【结果】①在基础培养液(DMEM 15%NBS)中添加10mM,20mM甜菜碱对三黄鸡胚胎原代成纤维细胞微核率无显著影响;添加30mM,40mM,50mM甜菜碱显著提高三黄鸡胚胎原代成纤维细胞的微核率。②在基础培养液(DMEM 15%NBS)中添加10mM、20mM甜菜碱能促进三黄鸡胚胎原代成纤维细胞的生长和增殖,以在培养液中添加20mM甜菜碱时三黄鸡原代成纤维细胞增殖速度最快。添加50mM甜菜碱时抑制了三黄鸡胚胎原代成纤维细胞的生长和增殖。【结论】低剂量甜菜碱可促进三黄鸡胚胎原代成纤维细胞的生长和增殖,高剂量甜菜碱对细胞分裂构成危害。     

Gamma Irradiation of Embryogenic Callus Cultures and In Vitro Selection for Salt Tolerance in Sugarcane (Saccharum officinarum L.)

Radiation induced mutagenesis followed by in vitro selection was employed for salt tolerance in popular Indian sugarcane (Saccharum officinarum L.) cv.CoC-671.Embryogenic calli were gamma irradiated and exposed to different levels of NaCl (42.8,85.6,128.3,171.1,213.9,256.7,299.5,or 342.2 mM).The relative growth rate (RGR) decreased progressively with increasing salt stress and was the least with a salt stress of 256.7 mM (0.25±0.009),almost 10 fold lesser than the control.The RGR was significantly lower in 85.6 mM and higher salt stressed calli than the control.The survival percent also decreased,with an increase in NaC1 concentration.In case of 10 and 20 Gy irradiated calli,regeneration was observed up to 85.6 mM NaCl selection,medium,whereas,higher treatments (128.3 mM and beyond) exhibited browning initially.However,in the subsequent subcultures,regeneration was obtained in the case of 10 and 20 Gy irradiated calli on 128.3 and 171.1 mM NaCI selections.Higher dose of gamma irradiation (40 Gy) also showed regeneration,but only with 85.6 mM NaCI selection.The unirradiated calli regenerated the highest number of plantlets followed by 10 and 20 Gy irradiated calli on salt selection.A total of 147 plantlets were selected from different salt levels.The salt selected plants are being tested for their field performance.