Concentration by freeze-thaw

A simple procedure for concentrating aqueous solution by freezing is described. Solutions are frozen in test tubes, which are insulated on the sides and bottom, and allowed to thaw during centrifugation. Fractionation of solutes could also be achieved.     

Regulation of JNK by Src during Drosophila development

In Drosophila, the Jun amino-terminal kinase (JNK) homolog Basket (Bsk) is required for epidermal closure. Mutants for Src42A, a Drosophila c-src protooncogene homolog, are described. Src42A functions in epidermal closure during both embryogenesis and metamorphosis. The severity of the epidermal closure defect in the Src42A mutant depended on the amount of Bsk activity, and the amount of Bsk activity depended on the amount of Src42A. Thus, activation of the Bsk pathway is required downstream of Src42A in epidermal closure. This work confirms mammalian studies that demonstrated a physiological link between Src and JNK.     

Simazine: Degradation by Soil Microorganisms

A soil fungus, Aspergillus fumigatus Fres., is effective in the degradation of the herbicide 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine). The degradation of both ring-and chain-labeled (C(14)) simazine was observed in an unamended and an amended (sucrose) basal medium. A loss of C(14) occurred in all culture solutions containing either ring-or chain-labeled simazine, but the decrease in activity observed was greater with chain-labeled than with ring-labeled simazine. Chromatographic evidence indicates that A. fumigatus may possess a degradation mechanism unlike that which occurs in corn plants.     

Antibody multispecificity mediated by conformational diversity

A single antibody was shown to adopt different binding-site conformations and thereby bind unrelated antigens. Analysis by both x-ray crystallography and pre-steady-state kinetics revealed an equilibrium between different preexisting isomers, one of which possessed a promiscuous, low-affinity binding site for aromatic ligands, including the immunizing hapten. A subsequent induced-fit isomerization led to high-affinity complexes with a deep and narrow binding site. A protein antigen identified by repertoire selection made use of an unrelated antibody isomer with a wide, shallow binding site. Conformational diversity, whereby one sequence adopts multiple structures and multiple functions, can increase the effective size of the antibody repertoire but may also lead to autoimmunity and allergy.     

高效好氧反硝化茵的紫外诱变育种

采用紫外诱变法对好氧反硝化菌A762进行诱变处理,根据显色圈大小（G）与菌落直径（c）之比,初筛得到8株突变菌,再根据脱氮效果,从中复筛出1株总氮（TN）去除率最高的突变株B25,并对其好氧反硝化性能进行了研究．结果显示：紫外诱变96h后,在好氧条件下,相对于原菌株A762,菌株B25具有更好的生长优势,对NO3--N去除率达到90％以上,远高于原菌的22．201％;能短时间内去除积累的亚硝态氮,TN去除率提高到84．627％,比原菌株A762提高了60．071％．在反硝化过程中,培养液pH值逐渐上升,而氧化还原电位（ORP）逐渐降低．虽然诱变株B25有较强的反硝化活性,但还要进一步研究其在养殖水体中的脱氮效果,以便能得到实际应用．     

鳗鲡幼苗种类的DNA指纹鉴定

养殖鳗鲡种苗来源日趋多样,确定鳗苗种类是决定养殖成败的关键因素之一。应用鳗鲡属鱼类mtDNA COI基因的保守序列设计一对特异性引物,对21批次,共109个白苗期鳗鲡样品进行种类鉴定。结果显示,应用该引物可以在所采集到的鳗鲡样品中扩增出652bp特异性基因片段,将样品COI基因序列与BOLD数据库中鳗鲡COI基因标准序列进行比对,共鉴定得7个种类归属,分别为日本鳗鲡A.japonica、美洲鳗鲡A.rostrata、欧洲鳗鲡A.anguilla、花鳗鲡A.marmorata、莫桑比克鳗鲡A.mossambica、吕宋鳗鲡A.luzonensis和太平洋双色鳗A.bicolor pacifica。对COI基因序列进行聚类分析,得到7个有很高节点支持率的主要类群。结果证实mtDNA COI基因在鳗鲡种类鉴定上具有很好的实用性。此外,在种类的鉴定中发现其中1批次的样品定种错误,有1个批次的鳗鲡样品中存在有2个种类的混杂,提示在实际的苗种养殖及交易中,对鳗鲡的种类鉴定上仍存在一定的错误和混杂,有必要引入DNA分子标记技术进行更加方便和准确的鉴定。     

Bacterial characterization by flow cytometry

Bacteria were analyzed in a dual-beam flow cytometer after double staining with the fluorescent dyes chromomycin A3 and Hoechst 33258, which bind preferentially to DNA that is rich in guanine-cytosine and adenine-thymine, respectively. The measurements were indicative of the cellular DNA content and base composition, cell concentration, and proliferative state of the population. The ratio of the chromomycin A3 signal to the Hoechst 33258 signal increased with the guanine-cytosine content of the cellular DNA for the six cultured species measured, following expectation. Bacteria in urine from patients with urinary tract infections were characterized without interference from host cell DNA, debris, or other particulates.     

Ionization of liquids by radiation: measurement by a clearing field

A method has been developed for determining the yield of free ions formed by irradiation of a liquid with high-energy x-rays. Contrary to expectation, branched-chain paraffins produce many more free ions than straight-chain paraffins do, and the ether 1,4-dioxane produced only a third as many free ions as its hydrocarbon analog, cyclohexane.     

Primary afferent depolarization evoked by a painful stimulus

Pulses of intense radiant heat applied to the plantar pad of unanesthetized spinal cats produced negative dorsal root potentials, increased excitability of cutaneous A fibers, and marked activation of ipsilateral flexor motoneurons. The same effects were obtained during cold block of A fiber conduction in the appropriate peripheral nerve. We conclude that adequate noxious activation of cutaneous C fibers depolarizes cutaneous A fibers.     

麻疫霉异宗配合变异株交配型的遗传

以化学农药氯唑灵诱变苎麻疫霉（ＰｈｙｔｏｐｈｔｈｏｒａｂｏｅｈｍｅｒｉａｅＳａｗａｄａ）的野生型菌株Ｅｃ－８获得异宗配合变异株,氯唑灵的有效诱变浓度为１０～３０μｇ／ｍＬ,以２０μｇ／ｍＬ处理３～８周效果最好。异宗配合变异株的交配型在单游动孢子或单菌丝片段后代均发生分离,出现了疫霉菌已知的全部５种交配型的个体。各交配型在单游动孢子无性系后代持续分离：Ａ１交配型菌株后代出现了Ａ１、Ａ２、Ａ０和Ａ１,Ａ２交配型,Ａ２交配型菌株后代出现了Ａ１、Ａ２、Ａ１Ａ２和Ａ０交配型,Ａ１,Ａ２交配型菌株后代出现了Ａ１、Ａ２、Ａ１Ａ２、Ａ０和Ａ１,Ａ２交配型,Ａ０交配型菌株后代出现了Ａ１、Ａ１Ａ２、Ａ０和Ａ１,Ａ２交配型,而部分回复为Ａ１Ａ２交配型的菌株后代也出现了Ａ１、Ａ２、Ａ１Ａ２、Ａ０和Ａ１,Ａ２５种交配型。８０％以上的变异株在１２°Ｃ、黑暗中贮存２个月后仍可保持其原有交配型,部分变异株在菌丝块移植继代培养７代后仍然保持异宗配合特性。对部分Ａ１交配型单孢株激素产生与接受类型的测定结果表明,Ａ１交配型变异株至少包括Ｓ１和Ｓ２两种性征类型。上述结果提示,疫霉属卵菌性别的产生可能是由同宗配合演化为异宗配合,并可能同时分化产生不     

扁桃属植物种质资源鉴定的SSR分析研究

利用SSR分子标记技术对国内外55份扁桃属植物材料的亲缘关系进行了鉴定,使用12对SSR引物组合共扩增出75条扩增条带,并对其进行聚类分析,结果表明:扁桃属植物不同种以及不同品种间的遗传距离不同,在相似系数小于0.68时,大多数栽培扁桃品种聚为一类, 栽培品种中同一种源区的大多数栽培品种能聚类在一起.从聚类图上看,普通栽培扁桃与新疆野扁桃间的亲缘关系比长柄扁桃、蒙古扁桃、西康扁桃以及榆叶梅间的亲缘关系更近.进一步证明利用分子指纹图谱能够对扁桃属种质资源进行科学系统的遗传分类.     

Blake outer ridge: development by gravity tectonics

A continuous seismic profile across the Blake Outer Ridge reveals clear evidence of a structural origin for the ridge. A ridge core separates distinctive regions of structure east and west of the crest and does not support a theory of depositional origin. The presence of horizon A continuously beneath the ridge rules out faulting or folding involving basement rocks. Gravity tectonics are suggested as the mechanism for formation of the ridge after the deposition of the sediments above horizon A.     

Adenovirus multiplication: inhibition by methisazone

Methisazone (5 to 40 microM) inhibited the multiplication of types 3, 7, 9, 11, 14, 16, 17, 21, and 28 adenovirus; SV15 (a simian adenovirus) was also inhibited. A study of adenovirus 11 under single-cycle conditions showed that multiplication of the virus, was completely inhibited by 30 microM methisazone when addition of the compound was delayed until 13 hours after infection. A survey showed that the structure-activity relations of the action of methisazone against adenoviruses and pox viruses are similar.     

14份杏种质的ISSR分析

以冀光为试材,研究了PCR反应体系的主要成分及退火温度对杏ISSR扩增结果的影响。同时,从42对ISSR引物中筛选出12对扩增条带清晰、多态性好的引物进行扩增,并运用UPGMA聚类分析法,分析了12份杏种质的亲缘关系及多样性。结果表明:在20μL的反应体系中,模板DNA含量在10~80 ng均能得到较好的扩增;dNTP用量对扩增无明显影响;而引物、Mg2+的最适浓度分别为0.25μmol/L、0.25 mmol/L;Taq酶在0.5~4 U均能得到好的扩增条带;退火温度在50~52.1℃范围内均能得到清晰的条带;并在此基础上建立了杏ISSR反应体系。当相似系数在0.444~0.452之间时,将12份杏材料划分为3类:①普通杏(Amentacavulgaris),西伯利亚杏(A.sibirica),辽杏(A.mandshurica),藏杏(A.holosericea)类型;②仁用杏品种一窝蜂;③紫杏(A.dasycarpa)。     

Ocean surface currents mapped by radar

A high-frequency radar remote-sensing system for measuring and mapping near-surface ocean currents in coastal waters has been analyzed and described. A transportable prototype version of the system was designed, constructed, and tested. With two units operating tens of kilometers apart, the currents were mapped in near real time at a grid of points 3 by 3 km covering areas exceeding 2000 kM(2), out to a distance of about 70 km from the shore. Preliminary estimates of the precision of current velocity measurements show it to be better than 30 cm/sec.     

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.     

三七的傅里叶变换红外光谱鉴别技术

[目的]寻找简便快捷的中药材品质分级方法。[方法]利用傅里叶变换红外光谱法对5种不同等级的三七（Radix notoginseng）和三七花进行测定。[结果]三七和三七花的光谱在1 800~700 cm-1范围差别明显;在特定吸光度比值上也表现出明显差异,吸光度比A1 242/A2 928、A1 080/A2 928、A1 020/A2 928三七比三七花大,而A1 643/A2 928、A1 416/A2 928、A1 372/A2 928三七比三七花小。不同等级三七的红外光谱峰形和峰位基本相同,但在特征吸收峰上的吸光度比值上存在着差别。不同头数的三七,其吸光度比A1 640/A2 928、A1 240/A2 928、A1 080/A2 928、A1 022/A2 928、A928/A2 928表现出的规律为20头〉40头〉60头〉80头〉100头。[结论]各样品的红外光谱,主要特征吸收峰上吸光度比的差异,说明它们中所含主要物质基本相同,但主要物质含量有差异。红外光谱法在鉴别中药材方面具有方便、快速、无损的特点,有望成为三七等级以及产地鉴别的标准方法。     

近红外漫反射光谱法对贵州产蜘蛛抱蛋属植物的分类

[目的]建立贵州产蜘蛛抱蛋属植物的近红外漫反射光谱分析方法.[方法]将赤水蜘蛛抱蛋、刺果蜘蛛抱蛋、丛生蜘蛛抱蛋、四川蜘蛛抱蛋、峨边蜘蛛抱蛋、广西蜘蛛抱蛋、贵州蜘蛛抱蛋、 荔波蜘蛛抱蛋等23批贵州产该属植物烘干、粉碎、过筛后直接测定其红外漫反射图谱;分别采用聚类分析,主成分分析等分析方法对该属植物进行分类.[结果]23批贵州产该属植物的近红外漫反射光谱相似程度极高,通过一阶导数对图谱进行处理,选取4000~7500 cm-1光谱范围作为分析区间,通过聚类分析和主成分分析对该属植物大量光谱变量进行转换,使数目较少的新变量成为原始变量的线性组合,从而让不同种之间的微小差异进一步扩大,从而直观的对该属植物进行分类.[结论]近红外漫反射光谱法可无损、快速测定固体样品,结合信息处理技术,可以为贵州产蜘蛛抱蛋属植物的分类提供一种新方法.     

用PCR检测猪胸膜肺炎放线杆菌

为了快速诊断猪的传染性胸膜肺炎，试验设计合成了1对引物，建立了检测猪胸膜炎肺放线杆菌的PCR方法，猪胸膜炎肺放线杆菌Ⅰ型菌血清2、5、6、9、10型均能扩增出预期片段；大肠杆菌，猪痢疾蛇形螺旋体、多杀性巴氏杆菌、鸡葡萄球菌和支气管败血性波氏杆菌的扩增结果均为阴性，用该方法检测了自猪肺脏分离的30个菌株，有11株为阳性，19株为阴性，结果证实，本方法可以用于猪胸膜肺炎的快速诊断。     

农杆菌介导的烟草瞬时表达试验条件优化

以烟草叶片为试材,用转入植物表达载体pBI121的根癌农杆菌EHA105进行遗传转化。通过分析菌液不同浓度、侵染时间、乙酰丁香酮浓度及共培养时间对GUS基因表达的影响,研究其瞬时表达的最佳条件。结果显示:用OD600值为0.6的农杆菌侵染6min,在培养基中添加120μmol.L-1的乙酰丁香酮,共培养2d,能够得到高效的GUS基因瞬时表达。