Subcellular fractions of mice thymocytes were used for sensitization of rabbits. The antisera were examined for their immunosuppressive
potency in vivo by allogeneic murine tumor metastases system and on skingraft survival and in vitro by leukocyte agglutination
tests. The results indicated that the most potent immunosuppressive antisera was that against the second fraction (Fr. 2)
of the detergent soluble endoplasmic reticulum fraction from thymocytes. 相似文献
Using plants to produce heterologous proteins makes it very attractive due to the potentially low costs. Using this procedure it is possible to produce medicinal protein for clinical applications with the plants bioreactors increasing gradually. The paper proposes the five major systems of the plant bioreactor as well as their advantage and disadvantage and the development of each system. Focuses on the five major systems of the plant bioreactor to produce vaccines, antibodies and medical protein and the research achievement at the present stage and the research on my laboratory. The key technology research of plant bioreactor such as new genes, new biological components,new technologies and new research methods related with plant bioreactor offer a work foundation for a long-term development in future. 相似文献
A familial outbreak of human parvovirus B19 infection is described in which serological tests carried out routinely for determining the causal agent of febrile rashes of viral etiology failed to yield a definitive diagnosis. Concurrent detection of serum IgMs to parvovirus B19 and to heterologous viruses such as human herpesvirus type 6 (HHV-6) and measles virus complicated interpretation of the data. IgG avidity tests and investigation and testing for the presence of viral DNA in sera by PCR were required to confirm parvovirus B19. The study stresses the importance of avidity and PCR tests to obtain a firm diagnosis of febrile exanthematic viral diseases. 相似文献
Amino terminal sequence modification of cytochrome P450 enzymes is often necessary to achieve expression in bacteria. The aim of this study was to examine the effect of such modifications on membrane integration and P450 activity.
Forms that retained substantial N-terminal hydrophobic sequences remained unaffected by treatments to remove peripheral membrane proteins and were released only by detergent. Truncated P450s 2A13, 2C9 (δ3–20), 2C19 (δ3–20), 2D6 (DB11) and 2E1 remained principally membrane-bound, but some P450 was found in the soluble fraction and could be partially extracted by alkaline and high salt treatments.
The subcellular localization of P450s 2C9 and 2C19 assessed by fluorescence microscopy mirrored the distribution between subcellular fractions. The MALLLAVFL modified forms of P450 2C9 YFP, P450 2C18 YFP and P450 2C19 YFP were found primarily at the periphery of the cells, whereas the truncated forms of P450 2C9 (δ3–20) YFP and 2C19 (δ3–20) YFP were observed at the periphery as well as inside the cells.
N-terminal variants of P450s 2C9 and 2C19 showed altered kinetics towards form-selective substrates. Rates of diclofenac 4´-hydroxylation by P450 2C9 and luciferin H-EGE metabolism by P450 2C19 were higher for the MALLLAVFL-modified forms compared with the (δ3–20) truncated forms despite supplementation of truncated form incubations with additional reductase.
Thus, N-terminal sequence modifications changed the degree of membrane integration, potentially affecting subcellular localization, interactions with redox partners, and hence enzymatic activity.
Expression of biosynthetic gene clusters in heterologous hosts for natural product production and combinatorial biosynthesis is playing an increasingly important role in natural product-based drug discovery and development programmes. This review highlights the requirements and challenges associated with this conceptually simple strategy of using surrogate hosts for the production of natural products in good yields and for the generation of novel analogues by combinatorial biosynthesis methods, taking advantage of the recombinant DNA technologies and tools available in the model hosts. Specific topics addressed include: i) the mobilisation of biosynthetic gene clusters using different vector systems; ii) the selection of suitable model heterologous hosts; iii) the requirement of post-translational protein modifications and precursor supply within the model hosts; iv) the influence of promoters and pathway regulators; and v) the choice of suitable fermentation conditions. Lastly, the use of heterologous expression in combinatorial biosynthesis is addressed. Future directions for model heterologous host engineering and the optimisation of natural product biosynthetic gene cluster expression in heterologous hosts are also discussed. 相似文献
Considerable effort has been directed toward the development of methods to selectively activate specific subtypes of neurons. Focus has been placed on the heterologous expression of proteins that are capable of exciting neurons in which they are expressed. Here we describe the heterologous expression of the invertebrate FMRFamide (H-phenylalanine-methionine-arginine-phenylalanine-NH(2)) -gated sodium channel from Helix aspersa (HaFaNaC) in hippocampal slice cultures. HaFaNaC was co-expressed with a fluorescent protein (green fluorescent protein (GFP), red fluorescent protein from Discosoma sp (dsRed) or mutated form of red fluorescent protein from Discosoma sp (tdTomato)) in CA3 pyramidal neurons of rat hippocampal slice cultures using single cell electroporation. Pressure application of the agonist FMRFamide to HaFaNaC-expressing neuronal somata produced large prolonged depolarizations and bursts of action potentials (APs). FMRFamide responses were inhibited by amiloride (100 muM). In contrast, pressure application of FMRFamide to the axons of neurons expressing HaFaNaC produced no response. Fusion of GFP to the N-terminus of HaFaNaC showed that GFP-HaFaNaC was absent from axons. Bath application of FMRFamide produced persistent AP firing in HaFaNaC-expressing neurons. This FMRFamide-induced increase in the frequency of APs was dose-dependent. The concentrations of FMRFamide required to activate HaFaNaC-expressing neurons were below that required to activate the homologous acid sensing ion channel normally found in mammalian neurons. Furthermore, the mammalian neuropeptides neuropeptide FF and RFamide-related peptide-1, which have amidated RF C-termini, did not affect HaFaNaC-expressing neurons. Antagonists of NPFF receptors (BIBP3226) also had no effect on HaFaNaC. Therefore, we suggest that heterologous-expression of HaFaNaC in mammalian neurons could be a useful method to selectively and persistently excite specific subtypes of neurons in intact nervous tissue. 相似文献