The use of nucleolytic enzymes (ribonucleases, polynucleotide phosphorylases and endonuclease from Serratia marcescens) for producing initial blocks of synthetic endoribonucleases]

The simplest variant of synthetic substrate-ribozyme complex has been proposed. The schemes of potential ribozyme "subunits" synthesis have been worked out: R1--GCUUGAAACAAA; R2--AAAAACUGAUGAAAGC. The macroscale synthesis of dinucleoside monophosphate ApU, GpC, CpU catalyzed by immobilized ribonucleases of different specificity and preparation of oligoadenylates by hydrolysis of poly-A in the presence of endonuclease Serratia marcescens, as well the synthesis of conservative sequences of potential ribozyme such as ApUpG, CpUpG, GpApU, ApApApG and others have been described.     

Some virus and virus-like diseases of tobacco,tomato, papaya,and rubber tree in vietnam and cambodia

In Vietnam a green strain of tobacco mosaic virus was isolated having TIP 89°C (10 min) and causing systemic necrosis in tobacoo ‘Xanthi-nc’ and sometimes also inDatura stramonium. In symptomless tomato plants an elongated virus belonging apparently to the Carlavirus group (NL 630 nm) was found. In papaya trees showing severe symptoms of mosaic and/or ringspot elongated virus particles (NL 730 nm) were observed; this virus being apparently a member of the Potyvirus group, resembled as far as its symptoms in papaya are concerned, the papaya ringspot or the distortion ringspot. In Cambodia some young rubber trees showed malformed leaves (esp. edges and veins) with yellow discolorations along the veins. Such leaves contained elongated virus-like particles (rigid or slightly flexible) of various length (60 to 880 nm), so that their normal length (NL) could not be established precisely. Particles 120 to 150 nm long occurred very frequently.     

抗菌肽对种植体周围炎主要致病菌生长抑制作用的研究

目的研究抗菌肽KSL及其衍生物KSL—W对种植体周围炎主要致病菌的体外抑菌效果。方法应用二倍稀释法检测KSL和KSL—W对血链球菌、具梭核杆菌和牙龈卟啉单胞菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）;MTT法检测KSL和KSL—W对成骨样细胞MG-63的细胞毒性。结果KSL和KSL—W对具梭核杆菌的MIC和MBC分别为0．0156mg／mL和0．0313mg／mL,对牙龈卟啉单胞菌的MIC和MBC分别为0．125mg／mL和0．5mg／mL,在0．5mg／mL的浓度范围内对血链球菌没有抑制作用;KSL和KSL-W在0．5mg／mL的浓度范围内没有细胞毒性。结论KSL和KSL—W没有细胞毒性,对具梭核杆菌和牙龈卟啉单胞菌具有抑制作用。     

The effect of modification of tRNA nucleotide-37 on the tRNA interaction with the P- and A-site of the 70S ribosome Escherichia coli

A modified nucleotide on the 3'-side of the anticodon loop of tRNA is one of the most important structure element regulating codon-anticodone interaction on the ribosome owing to the stacking interaction with the stack of codon-anticodon bases. The presence and identity (pyrimidine, purine or modified purine) of this nucleotide has an essential influence on the energy of the stacking interaction on A- and P-sites of the ribosome. There is a significant influence of the 37-modification by itself on the P-site, whereas there is no such one on the A-site of the ribosome. Comparison of binding enthalpies of tRNA interactions on the P- or A-site of the ribosome with the binding enthalpies of the complex of two tRNAs with the complementary anticodones suggests that the ribosome by itself significantly endows in the thermodynamics of codon-anticodon complex formation. It happens by additional ribosomal interactions with the molecule of tRNA or indirectly by the stabilization of codon-anticodon conformation. In addition to the stacking, tRNA binding in the A and P sites is futher stabilized by the interactions involving some magnesium ions. The number of them involved in those interactions strongly depends on the nucleotide identity in the 37-position of tRNA anticodon loop.