东北白眉蝮蛇毒细胞毒组分的分离制备及活性鉴定

用离子交换层析和凝胶过滤法从东北白眉蝮蛇毒中分离出一种具有较强的细胞毒活性的蛋白质。这种蛋白质对肿瘤细胞的细胞毒作用元选择性,但各种肿瘤细胞的敏感性有一定差别。对正常人体细胞也有一定的细胞毒性作用,与肿瘤细胞相比,敏感性较低。这种蛋白质加热到56℃,30分钟,细胞毒活性稳定。4℃及-20℃保存4个月,细胞毒活性稳定。PH值低于4及高于9时,可使其完全失活。     

Initiation of minus-strand RNA synthesis by the brome mosaicvirus RNA-dependent RNA polymerase: use of oligoribonucleotide primers.

Various DNA- and RNA-dependent RNA polymerases have been reported to use oligoribonucleotide primers to initiate nucleic acid synthesis. For the brome mosaic virus RNA-dependent RNA polymerase (RdRp), we determined that in reactions performed with limited GTP concentrations, minus-strand RNA synthesis can be stimulated by the inclusion of guanosine monophosphate or specific oligoribonucleotides. Furthermore, guanylyl-3',5'-guanosine (GpG) was incorporated into minus-strand RNA and increased the rate of minus-strand RNA synthesis. In the presence of GpG, RdRp's Km for GTP decreased from 50 microM to approximately 3 microM while the Kms for other nucleotides were unaffected. These results have implications for the mechanism of initiation by RdRp.     

Resuscitation of Vibrio cholerae O1 strain TSI-4 from a viable but nonculturable state by heat shock

Abstract Vibrio cholerae strain TSI-4 was incubated in an M9 salt solution at 15 °C for more than 100 days. The plate counts showed no viable cells on day 30, but a broth culture from that day showed the growth of bacteria. However, after 35 days the bacteria entered the nonculturable state, based on the assessment of both the plate counts and broth culture. A portion of the culture was heated at 45 °C for 1 min in a water bath and subsequently plated onto a nutrient agar plate. More than 1000 colonies were recovered after this heat-shock treatment. The recovered cells showed the same chromosomal DNA pattern in the restriction map and the same outer membrane protein pattern in SDS-PAGE. Recovery of viable cells by heat-shock was achieved in cultures grown on M9 salt but not from cultures grown in phosphate-buffered saline. This suggests that the presence of NH₄Cl in the M9 salt solution may support the growth of the bacteria in a low nutrient medium, while also playing an important role in resuscitation.     

A single tryptophan on M2 of glutamate receptor channels confers high permeability to divalent cations.

Ionotropic glutamate receptors (iGluRs) of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate/kainate subtype display lower permeability to Ca2+ than the N-methyl-D-aspartate (NMDA) subtype. The well-documented N/Q/R site on the M2 transmembrane segment (M2) is an important determinant of the distinct Ca2+ permeability exhibited by members of the non-NMDA receptor subfamily. This site, however, does not completely account for the different permeation properties displayed by non-NMDA and NMDA receptors, suggesting the involvement of other molecular determinants. We have identified additional molecular elements on M2 of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate/kainate receptor GluR1 that specify its permeation properties. Higher permeability to divalent over monovalent cations is conferred on GluR1 by a tryptophan at position 577, whereas blockade by external divalent cations is imparted by an asparagine at position 582. Hence, the permeation properties of ionotropic glutamate receptors appear to be primarily specified by two distinct determinants on M2, the well-known N/Q/R site and the newly identified L/W site. These findings substantiate the notion that M2 is a structural component of the pore lining.     

Evidence for ion chain mechanism of the nonlinear charge transport of hydrophobic ions across lipid bilayers.

The conductivity across a lipid bilayer by tetraphenylborate anion is increased 10-fold on the photoformation of lipophilic porphyrin cations. The cations alone have negligible conductivity. This nonlinear photogenerated increase of ion conductivity is termed the photogating effect. Substitution of H by Cl in the para position of tetraphenylborate leads to a 100-fold enhancement of conductivity, whereas the dark conductivities for this and other substituted borates are the same. Moreover, the halo-substituted borates show a large enhancement of conductivity in the low concentration range (10(-8) M), whereas that of tetraphenylborate is small and space charge is negligible. The enhanced ion conductivity has great structural sensitivity to the structure of the anion, the cation, and the lipid, whereas the partition coefficient of all the borates and the concentration of photoformed cations are only slightly affected. The photogated ion transport has a twofold larger activation energy than transport in the dark. Time-resolved photocurrents and voltages demonstrate that the translocation rate of the porphyrin cation is also enhanced 100-fold by the Cl-borate anion but only 10-fold by the H-borate anion. For these reasons the nonlinear gating effect cannot be explained by electrostatics alone, but requires an ion chain or ion aggregate mechanism. Kinetic modeling of the photoinduced current with a mixed cation-anion ion chain can fit the data well. The photogating effect allows the direct study of ion interactions within the bilayer.     

锈寄生菌对落叶松褐锈病的抑制效应

目测及镜检结果表明,褐锈菌被锈寄生菌寄生后,夏孢子堆由桔红渐变为灰褐,后期夏孢子失去发芽力,孢子堆原基处只存有寄生菌的分生孢子器．锈寄生菌的发酵液代谢产物含有３种抗性物质．自７月中下旬至９月中旬,分生孢子的发生量多于褐锈菌的孢子量,表明落叶松褐锈病的发生程度随着锈寄生菌寄生率的增加而减轻．     

棉铃虫病毒杀虫乳悬剂的生产及其药效试验

成功研制出棉铃虫病毒（ＮＰＶ）杀虫乳悬剂,改进了生产工艺和设备,建立了棉铃虫的室内品系,提高了生产效率,建立了产品的检测方法,提高了产品质量,促使棉铃虫病毒杀虫剂商品开发获得成功。大田试验证明,病毒乳悬剂的防治效果,相当于当前推广的化学农药,优于原病毒可湿性粉剂。相同剂量（０．５３一１．０７×１０（１０）ＰＩＢ／公顷）的病毒乳悬剂可使虫口平均减退９１．７％,而病毒可湿性粉剂为８３．７％。     

Cloning and functional characterization of LCR-F1: a bZIP transcription factor that activates erythroid-specific,human globin gene expression.

DNase I hypersensitive site 2 (HS 2) of the human beta-globin Locus Control Region (LCR) directs high level expression of the beta-globin gene located 50 kilobases downstream. Experiments in cultured cells and in transgenic mice demonstrate that duplicated AP1-like sites in HS 2 are required for this powerful enhancer activity. A cDNA clone encoding a basic, leucine-zipper protein that binds to these sites was isolated and designated Locus Control Region-Factor 1 (LCR-F1). This protein is a member of a new family of regulatory factors that contain a 63 amino acid ''CNC domain'' overlapping the basic region. This domain is approximately 70% identical in the Drosophila Cap N Collar (CNC) protein, NF-E2 and LCR-F1. LCR-F1 transactivates an HS 2/gamma-globin reporter gene over 170-fold in transient transfection experiments specifically in erythroid cells. These results suggest that LCR-F1 may be a critical factor involved in LCR-mediated, human globin gene expression.