点状产气单胞菌脯氨酰内肽酶基因克隆与序列测定

点状产气单胞菌点状亚种（Ａｅｒｏｍｏｎａｓ ｐｕｎｃａｔａ ｓｕｂｓｐ．ｐｕｎｃｔａｔａ）具有脯氨酰内肽酶（ｐｒｏｌｙｌ ｅｎｄｏｐｅｐｔｉｄａｓｅ ＰＥＰ）活性。将其染色体ＤＮＡ有Ｅｃｏ ＲⅠ部分酶切后回收８－１６ｋｂ的ＤＮＡ片段,与ＥｃｏＲⅠ消化载体ｐＵＣ１８连接后转化Ｅ．ｃｏｉｌ ＤＨ５α,用该酶的专一性底物Ｂｅｎｚｙｌｏｘｙｃａｒｂｏｎｙｌ－Ｇｌｙ－β－ｎａｐｈｔｈｙｌａｍｉｄｅ从质粒库中     

华南胡椒化学成分的研究

从胡椒科植物华南胡椒（Ｐｉｐｅｒ ａｕｓｔｒｏｓｉｎｅｎｓｅ Ｃ．ＤＣ．）中分离出七个成分,经光谱分析和理化常数测定,分别鉴定为Ｎ－ｉｓｏｂｕｔｙｌ－３（３＇,４＇－ｍｅｔｈｙｌｅｎｅｄｉｏｘｙ－５＇－ｍｅｔｈｏｘｙｐｈｅｎｙｌ）－２Ｅ－ｔｒｉｍｏｎｏｉｅｎａｍｉｄｅ（Ｉ）、Ｎ－ｉｓｏｂｕｔｙｌ－７（３＇,４＇－ｍｅｔｙｌｅｎｅｄｉｏｘｙｐｈｅｎｙｌ）－２Ｅ,４Ｅ－ｈｅｐｔａｄｉｅｎａｍｉｄｅ（Ⅱ     

不同农田生态系统土壤碳库管理指数的研究

讨论不同农田生态系统的土壤活性碳库和碳库管理（ＣＰＭＩ）,结果表明,不同农田生态系统的土壤ＣＰＭＩ明显受施肥、气候、土壤利用方式,耕种年限等因素的影响。供试土壤的活性碳含量范围为０．４９～４．９９ｍｇ／ｇ,土壤ＣＰＭＩ为５１．６～１６５。不同施肥地红壤ＣＰＭＩ的影响顺序为绿肥（ＧＭ）〉概肥（ＦＹＭ）〉ＦＹＭ－ＮＰＤ〉参考（ＲＥＦ）〉ＮＰＫ〉对照（ＣＫ）,在水稻土中,共相应的影响顺序为,稻草（ＲＳＣ     

亚洲棉GAE6—3A上游序列的分离及其在烟草中的表达

根据Ｅ６基因保守域设计引物,ＰＣＲ扩增出亚洲棉（Ｇａｓｓｙｐｉｕｍ ａｒｂｏｒｅｕｍ Ｌ．）ＧＡＥ６基因长约４００ｂｐ片段,序列分析表明该片段与海棉（Ｇ．ｂａｒｇｂａｄｅｎｓｅ）Ｅ６基因同源性达９６．８％。进一步合成２个反向引物协助进行ＰＣＲ－９６孔板筛库分离到亚洲板棉ＧＡＥ６－３Ａ克隆。酶切鉴定其插入片段长约８．０ｋｂ,序列测定及分析结果表明其上游和约１．５ｋｂ,将ＧＡＥ６－３Ａ上游序列克 含有     

枯草芽孢杆菌中性内切β-甘露聚糖酶的纯化及性质

三草芽孢杆菌（Ｂａｃｉｌｌｕｓ ｓｕｂｔｉｌｉｓ）ＢＭ９６０２产生的中性内切β－甘露聚糖酶（ｅｎｄｏ－β－１,４－Ｄ－ｍａｎｎａｎ ｍａｎｎａｎｏｈｙｄｒｏｌａｅｓ,ＥＣ,３．２．１．７８）经硫酸铵分级沉淀、ＤＥＡＥ－纤维素（ＤＥ２２）离子交换柱层析,得到电泳纯的样品,提纯了４５．５倍,收率为５．９％。用ＳＤＳ－ＰＡＧＥ测得该酶的分子量为３５ｋＤ。用ＰＡＧＥＩＥＦ测得其等电点ｐⅠ为４．５。酶反应的     

绿豆芽超微弱发光的二维图像探测

采用微通道板像增强研制了一种能探测极弱光图像的超高灵敏度光电探测系统,能够探测到０．５Ｐｈｏｔｏｎｓ／ｍｍ２·ｓ（阴极灵敏度）的极弱发光图像,是目前弱光图像探测器中灵敏度最高的。应用上述的光电探测系统,进行了绿豆芽超微弱发光二维图像探测的研究,首次得到了以下结论：１．绿豆发芽时存在超微弱发光现象,发光强度在１０４－１０５Ｐｈｏｔｏｎｓ／ｓ·ｃｍ２的范围内;２．子叶和幼叶的发光高于幼茎的发光;３．在避先保持１０分钟豆芽发光衰减至稳定后,绿豆芽仍能维持一定的发光。上述结论为超微弱发光现象的生物学理论研究和医学及环境保护中的应用提供了实验依据。     

蚯蚓体内一种纤溶酶原激活剂(e-PA)对ATEE的降解

赤子爱胜蚓（Ｅｉｓｅｎｉａｆｅｔｉｄａ）体内的一种纤溶酶原激活剂（ｅ－ＰＡ）能够降解人工合成底物Ｎ－乙酰－Ｌ－酪氨酸乙酯（ＡＴＥＥ）,该降解反应的最适ｐＨ为８．５,而且在０．２ｍｏｌ／ＬＮａ２ＨＰＯ４中的活性要强于在０．０５ｍｏｌ／ＬＴｒｉｓ－ＨＣｌ（ｐＨ８．５）中．分别测定了ｅ－ＰＡ的大小亚基及全酶在０．２ｍｏｌ／ＬＮａ２ＨＰＯ４与０．０５ｍｏｌ／ＬＴｒｉｓ－ＨＣｌ（ｐＨ８．５）两种体系中的Ｋｍ和Ｋｃａｔ．结果表明,在０．２ｍｏｌ／ＬＮａ２ＨＰＯ４中,全酶的ＡＴＥＥ活性远远高于大小亚基单独的ＡＴＥＥ活性,而在０．０５ｍｏｌ／ＬＴｒｉｓ－ＨＣｌ（ｐＨ８．５）中则没有这种现象．从蛋白质结构的角度对这一结果作了解释．用不同抑制剂和ｅ－ＰＡ作用,结果表明,ｐｅｐｓｔａｔｉｎ,Ｅ－６４和ＥＤＴＡ对ｅ－ＰＡ的ＡＴＥＥ活性都有不同程度的抑制,这一点与ｅ－ＰＡ的ＢＡＥＥ活性不同．     

大锥蚤属一新种记述（蚤目：角时蚤科）

本文记述大锥蚤属ＭａｃｒｏｓｔｙｌｏｐｈｏｒａＥｗｉｎｇ,１９２９－新种,木鱼大雄蚤Ｍａｃｒｏｓｔｙｌｏｐｈｏｒａｍｕｙｕｅｎｓｉｓｓｐ．ｎｏｖ,采自湖北省西北部神农架林区的棕足鼯鼠窝（Ｐｅｔａｕｒｉｓｔａｃｌａｒｋｅｉ）和岩松鼠（Ｓｃｉｕｒｏｔｍｉａｓｄａｖｉｄｉａｎｕｓ）体上,模式标本分别存放湖北省医学科学院寄生虫病研究所和福建医学院医学昆虫研究室。     

蚯蚓体内一种纤溶酶原激活剂(e-PA)对BAEE的降解

以苯甲酰－Ｌ－精氨酸乙酯（ｂｅｎｚｏｙｌ－Ｌ－ａｒｇｉｎｉｎｅｅｔｈｙｌｅｓｔｅｒ,ＢＡＥＥ）为底物,研究了蚯蚓体内纤溶酶原激活剂（ｐｌａｓｍｉｎｏｇｅｎａｃｔｉｖａｔｏｒｆｒｏｍＥｉｓｅｎｉａｆｅｔｉｄａ,ｅ－ＰＡ）的酶学性质．酶促反应的最适ｐＨ为８．４,ｅ－ＰＡ降解ＢＡＥＥ的Ｋｍ为１．２４±０．１６×１０－５ｍｏｌ／Ｌ,Ｋｃａｔ为１３．８０±４．０２ｓ－１．测定了构成ｅ－ＰＡ的大,小亚基分别降解ＢＡＥＥ的Ｋｍ和Ｋｃａｔ．结果表明,大亚基的Ｋｍ与全酶的Ｋｍ相差不多,但比小亚基小约１０倍,即对底物的亲和力比小亚基强约一个数量级．大小亚基的Ｋｃａｔ比较接近,分别是全酶的１／６和１／３．研究了８种抑制剂对ｅ－ＰＡ降解ＢＡＥＥ活性的影响,其中ｐｅｐｓｔａｔｉｎ和Ｅ－６４（一种巯基抑制剂）对酶促反应有激活作用,ＴＰＣＫ,ＴＬ－ＣＫ,ＰＭＳＦ,ｃｈｙｍｏｓｔａｔｉｎ和ｌｅｕｐｅｐｔｉｎ对其有不同程度的抑制作用,ＥＤＴＡ对ｅ－ＰＡ的活性没有影响．对ｅ－ＰＡ的ＢＡＥＥ活性和ｅ－ＰＡ的纤溶活性之间作了比较．     

几种生态因子对双齿围沙蚕早期生活的影响

几种生态因子对双齿围沙蚕早期生活的影响石小平,赵清良（安徽师范大学,芜湖２４１０００）（南京师范大学,２１００２４）ＥｆｆｅｃｔｓｏｆｓｅｖｅｒａｌＥｃｏｌｏｇｉｃａｌＦａｃｔｏｒｓｏｎＥａｒｌｙＳｔａｇｅ,ｓｕｒｖｉｖａｌａｎｄＧｒｏｗｔｈｏｆＰｅｒｉｎｅｒｅｉｓＡｉｂｕｈｉｔｅｎｓｉｓ￥ＳｈｉＸｉａｏｐｉｎｇ（ＡｎｈｕｉＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ,Ｗｕｈｕ２４１０００）,ＺｈａｏＱｉｎｇｌｉａｎｇ（ＨａｎｊｉｎｇＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ,２１００２４）．（Ｃｈｉｎｅｓｅ,ＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（５）：２１－２４。ＴｈｉｓｐａｐｅｒｄｅａｌｓｗｉｔｈｔｈｅｅｆｆｅｃｔｓｏｆｐＨ,ｓａｌｉｎｉｔｙ,ｄｅｎｓｉｔｙａｎｄｍｅｄｉｕｍｏｎｔｈｅｅａｒｌｙｓｔａｇｅ－ｄｅｖｅｌｏｐｍｅｎｔａｎｄｇｒｏｗｔｈｏｆＰｅｒｉｎｅｒｅｉｓａｉｂｕｈｉｌｎｅｓｉｓ．ＴｈｅｒｅｓｕｌｔｓｓｈｏｗｔｈａｔｔｈｅｏｐｔｉｍｕｍｐＨｆｏｒｉｔｓｈａｔｃｈｉｎｇｉｓ７．０－７．５,ｕｎｄｅｒｗｈｉｃｈ,ｓｕｉｔａｂｌｅｓｌｉｎｉｔｙｉｓｉｎｔｈｅｒａｎｇｅｏｆ１５－４０％,ａｎｄＴｈｅｓｕｉｔ     

Introducing a new (freeware) tool for palynology

We present a multiple-access key and searchable data base to Neotropical pollen that is available as freeware. The data base is based on FileMaker 5 and contains c . 6000 images of >1000 taxa. All pollen images are of acetolysed grains collected from vouchered herbarium specimens. The selection of taxa to be included in the data base is predicated upon their probable occurrence in lake sedimentary records, which in turn was based on their flower structure, sexual mechanisms and ecology. The multiple-access key is a forgiving format as it can be used with incomplete data or where the researcher cannot decide between the choices offered. The data base is downloadable and is compatible with both Mac and PC platforms.     

Analysis of rotifer ribosomal gene structure using the polymerase chain reaction (PCR)

We have used the polymerase chain reaction (PCR) to selectively amplify 18S ribosomal genes in rotifer taxa from major planktonic clades. In each case, we obtained an amplified product of between 1.8 and 2.0 kilobase pairs. We analyzed the PCR products using 6- and 4-base cutting restriction enzymes, comparing fragment mobilities. For example, Brachionus plicatilis (BSL strain) 18S genes have no restriction sites for Hind III or Bam HI and only a single site for Eco RI (all 6-base cutters). The 4-base cutter Msp I, on the other hand, has at least 4 enzymatic sites, producing fragments between approximately 110 and 460 base pairs in length. Results of this type can be used to differentiate among species and species groups within the Rotifera and can be used as the basis for construction of a broad molecular phylogeny of the group.     

Cloning, sequence, and expression of the Drosophila cAMP-dependent protein kinase catalytic subunit gene

Genomic DNA containing the protein coding region for Drosophila cAMP-dependent protein kinase catalytic subunit has been cloned and sequenced. The probe used to detect and isolate the gene fragment was constructed from two partially complementary synthetic oligonucleotides and contains 60 base pairs that encode (using Drosophila codon preferences) amino acids 195-214 of the beef heart catalytic subunit. In reduced stringency hybridization conditions, the probe recognizes two target sites in fly genomic DNA with 85% homology. One of these sites is in the cAMP-dependent protein kinase catalytic subunit gene, which was isolated as a 3959-base pair HindIII fragment. This fragment contains all of the protein coding portion, 900 base pairs upstream of the initiator ATG, and 2000 base pairs downstream of the termination codon (TAG). The coding portion of the gene contains no introns and yields a protein of 352 amino acids. There is a 2-amino acid insertion near the N terminus of the fly protein relative to the beef and mouse enzymes. Of the remaining 350 amino acids, 273 are invariant in the three species. A probe derived from the coding sequence of the HindIII clone hybridizes strongly to a 5100-base poly(A)+ RNA and weakly to 4100- and 3400-base poly(A)+ RNAs expressed in adult flies. A 2100-base pair EcoRI genomic fragment containing the second site recognized by the 60-base pair probe has also been cloned. DNA sequence analysis demonstrates that this fragment is part of the cGMP-dependent protein kinase gene or a close homolog. The catalytic subunit gene and the cGMP-dependent protein kinase gene have been located in regions 30C and 21D, respectively, of chromosome 2.     

The power of PowerPoint

Carousel slide presentations have been used for academic and clinical presentations since the late 1950s. However, advances in computer technology have caused a paradigm shift, and digital presentations are quickly becoming standard for clinical presentations. The advantages of digital presentations include cost savings; portability; easy updating capability; Internet access; multimedia functions, such as animation, pictures, video, and sound; and customization to augment audience interest and attention. Microsoft PowerPoint has emerged as the most popular digital presentation software and is currently used by many practitioners with and without significant computer expertise. The user-friendly platform of PowerPoint enables even the novice presenter to incorporate digital presentations into his or her profession. PowerPoint offers many advanced options that, with a minimal investment of time, can be used to create more interactive and professional presentations for lectures, patient education, and marketing. Examples of advanced PowerPoint applications are presented in a stepwise manner to unveil the full power of PowerPoint. By incorporating these techniques, medical practitioners can easily personalize, customize, and enhance their PowerPoint presentations. Complications, pitfalls, and caveats are discussed to detour and prevent misadventures in digital presentations. Relevant Web sites are listed to further update, customize, and communicate PowerPoint techniques.     

Site-specific insertion of genes into integrons: role of the 59-base element and determination of the recombination cross-over point

From examination of published DNA sequences of genes found inserted at a specific site in integrons, all genes are shown to be associated, at their 3' ends, with a short imperfect inverted repeat sequence, a 59-base element or relative of this element. The similarity of the arrangement of gene inserts in the integron and in the Tn7 transposon family is described. A refined consensus for the 59-base element is reported. Members of this family are highly diverged and the relationship of a group of longer elements to the 59-base elements is demonstrated. The ability of 59-base elements of different length and sequence to act as sites for recombination catalysed by the integron-encoded DNA integrase is demonstrated, confirming that elements of this family have a common function. The ability of elements located between gene pairs to act as recombination sites has also been demonstrated. The recombination cross-over point has been localized to the GTT triplet which is conserved in the core sites, GTTRRRY, found at the 3' end of 59-base elements. Recombination at the core site found in inverse orientation at the 5' end of the 59-base elements was not detected, and the sequences responsible for orientation of the recombination event appear to reside within the 59-base element. A model for site-specific insertion of genes into integrons and Tn7-like transposons is proposed. Circular units consisting of a gene associated with a 59-base element are inserted into an ancestral element which contains neither a gene nor a 59-base element.(ABSTRACT TRUNCATED AT 250 WORDS)     

SILMUT: a computer program for the identification of regions suitable for silent mutagenesis to introduce restriction enzyme recognition sequences.

We describe a set of IBM-compatible computer programs designed to selectively identify the potential sites for silent mutagenesis within a target DNA sequence. This program is based on a novel strategy of identifying amino acid motifs compatible with each restriction site (BioTechniques 12:382-384, 1991). The programs can be used to identify the suitability for the introduction of any 6-base nucleic acid sequences, such as restriction enzyme sites in cassette mutagenesis strategies. The Table program generates a table of multiple amino acid motifs for each restriction enzyme, obtained by translating each unique recognition sequence in all three reading frames. The Silmut program, which utilizes the features of Table, will further identify the presence of a match between any amino acid motif of each restriction enzyme and the input target sequence. Minor manipulations of the data base files will enable the individual researcher to identify the potential for introduction of any 6-base sequences by silent mutagenesis.     

The structure of B-helical C-G-A-T-C-G-A-T-C-G and comparison with C-C-A-A-C-G-T-T-G-G. The effect of base pair reversals

The crystal structure of the DNA decamer C-G-A-T-C-G-A-T-C-G has been solved to a resolution of 1.5 A, with a final R-factor of 16.1% for 5,107 two-sigma reflections. Crystals are orthorhombic space group P2(1)2(1)2(1), with cell dimensions a = 38.93 A, b = 39.63 A, c = 33.30 A, and 10 base pairs/asymmetric unit. The final structure contains 404 DNA atoms, 142 water molecules treated as oxygen atoms, and two Mg(H2O)6(2+) complexes. Decamers stack atop one another to simulate continuous helical columns through the crystal, as with three previously solved monoclinic decamers, but the lateral contacts between columns are quite different in the orthorhombic and monoclinic cells. Narrow and wide regions of the minor groove exhibit a single spine or two ribbons of hydration, respectively, and the minor groove is widest when BII phosphate conformations are opposed diagonally across the groove. Phosphate conformation, in turn, appears to have a base sequence dependence. Twist, rise, cup, and roll are linked as has been observed in the three monoclinic decamers and can be characterized by high or low twist profiles. In all five known decamer crystal structures and eight representative dodecamers, a high twist profile is observed with G-C and G-A steps whereas all other R-R steps are low twist profiles (R = purine). A-T and A-C steps are intermediate in character whereas C-A and C-G exhibit behavior that is strongly influenced by the profiles of the preceding and following steps. When sufficient data are in hand, sequence/structure relationships for all helix parameters probably should be considered in a 4-base pair context. At this stage of limited information the problem is compounded because there are 136 unique 4-base steps x-A-B-y in a double helix as compared with only 10 2-base steps A-B.     

Minimal DNA requirement for topoisomerase II-mediated cleavage in vitro

The minimal DNA requirement for topoisomerase II-mediated DNA cleavage in vitro was determined by analyzing the interaction of the enzyme with sets of DNA substrates varying successively by single bases at the 5'- or 3'-end of either strand. A 16-base pair double-stranded region was established as the minimal duplex region required for topoisomerase II cleavage activity. The region was located symmetrically around the 4-base staggered cleavage site. Topoisomerase II-mediated cleavage within the 16-base pair core duplex, however, required single-stranded regions flanking the duplex to either the 5'- or 3'-sides, or an extension at both ends of the duplex with 1 or more base pairs.