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991.
992.
Expression of hematopoietic inhibitory factors in mouse fibroblasts,macrophages and endothelial cells 总被引:7,自引:0,他引:7
Pure bone marrow fibroblasts, macrophages and endothelial cells were cultured in Iscove-modified Dulbecco's medium. RT-PCR was used to determine the expression of inhibitory cytokine mRNAs in these cell types. Serum-free conditioned medium was collected from each cell type and ultrafiltration was performed with a centriprep 10. The retentate contained substances whose molecular weights were >10 kD, whilst the filtrate contained substances with molecular weights <10 kD. The effect of conditioned media and their components on colony forming unit-granulocyte-macrophage (CFU-GM) were investigated. The results showed: (1) six cytokines, MIP-1alpha, MIP-2, TGF-beta, TNF-alpha, IFN-gamma and Tbeta(4), inhibited the growth of CFU-GM when murine WEHI-3 conditioned medium was added to the culture system as a source of colony stimulation. (2) The original endothelial cell conditioned medium (E-CM) did not affect the production of CFU-GM, but the >10 kD component of E-CM increased its production, and the <10 kD component decreased it. Both fibroblast conditioned medium (F-CM) and the >10 kD component of F-CM stimulated proliferation of CFU-GM, but the <10 kD component suppressed it. All three components of macrophage conditioned medium (M-CM) inhibited the growth of CFU-GM. (3) Expression of four of the mRNAs, namely MIP-2, TNF-alpha, INF-gamma and Tbeta(4), was seen in all three types of stromal cells, while TGF-beta mRNA was only seen in endothelial cells and macrophages, and MIP-1alpha mRNA in endothelial cells and fibroblasts. The inhibitors TGF-beta, MIP-1alpha, and Tbeta(4)have an inhibitory effect on the growth of CFU-GM, but TNF-alpha, INF-gamma and MIP-2 do not. 相似文献
993.
994.
Huang Y Cui Q Wang L Rodriguez C Quintana E Goodfellow M Liu Z 《Antonie van Leeuwenhoek》2004,86(2):159-165
The taxonomic position of three acidophilic actinomycetes isolated from acidic rhizosphere soil was established using a polyphasic approach. The morphological and chemical properties of the isolates were found to be consistent with their assignment to the genus Streptacidiphilus. Almost complete 16S rRNA gene sequences determined for the strains were aligned with corresponding sequences of representatives of the genera Kitasatospora, Streptacidiphilus and Streptomyces and phylogenetic trees inferred using three tree-making algorithms. The organisms formed a distinct subclade within the Streptacidiphilus 16S rRNA gene tree. They also shared nearly identical phenotypic profiles and rep-PCR fingerprint patterns that readily distinguished them from representatives of the established species of Streptacidiphilus. It is evident from the genotypic and phenotypic data that the three isolates form a new species in the genus Streptacidiphilus. The name proposed for this new species is Streptacidiphilus jiangxiensis, the type strain is isolate 33214T (= AS 4.1857T = JCM 12277T). 相似文献
995.
Wu KP Wu CW Tsao YP Kuo TW Lou YC Lin CW Wu SC Cheng JW 《The Journal of biological chemistry》2003,278(46):46007-46013
The flavivirus envelope protein is the dominant antigen in eliciting neutralizing antibodies and plays an important role in inducing immunologic responses in the infected host. We have determined the solution structure of the major antigenic domain (domain III) of the Japanese encephalitis virus (JEV) envelope protein. The JEV domain III forms a beta-barrel type structure composed of six antiparallel beta-strands resembling the immunoglobulin constant domain. We have also identified epitopes of the JEV domain III to its neutralizing antibody by chemical shift perturbation measurements. Site-directed mutagenesis experiments are performed to confirm the NMR results. Our study provides a structural basis for understanding the mechanism of immunologic protection and for rational design of vaccines effective against flaviviruses. 相似文献
996.
Insulin-like growth factor 1 (IGF-1) mediates many of the actions of growth hormone. Overexpression of IGF-1 was reported to have endocrine and paracrine/autocrine effects on somatic growth in transgenic mice. To study the paracrine/autocrine effects of IGF-1 in mammary gland, transgenic mice were produced by pronuclear microinjection of a construct containing a bovine alpha-lactalbumin (alpha-LA) promoter linked to an ovine IGF-1 cNDA. This alpha-LA promoter has previously been shown to direct expression of a human factor VIII gene specifically to the mammary gland of transgenic mice. Three transgenic mouse lines were established as a result of microinjection of 398 embryos. Transgene expression was found in mammary gland at day 1 of lactation from these three lines. Progeny test were carried out by mating two transgenic males/one transgenic female to two nontransgenic females/one nontransgenic male. Mice from one line (line 1225) were all nonexpressors and the other (line 1372) failed to produce offspring. Milk yield was analyzed in the line 1137 that produced 10 mice, of which three were transgenic females and three nontransgenic females. All of the three transgenic females showed integration of the transgene and expressed transgene IGF-1 mRNA in the mammary gland. Milk yields from days 5, 10, and 15 of lactation were significant greater in transgenic expressors than in their nontransgenic littermates. Specifically, there is 17.9% increase in total milk yield from these three days for transgenics compared with nontransgenics. These results demonstrate that local overexpression of IGF-1 in transgenic mice is capable to stimulating milk yield during the first lactation. 相似文献
997.
BmBKTx1, a novel Ca2+-activated K+ channel blocker purified from the Asian scorpion Buthus martensi Karsch 总被引:1,自引:0,他引:1
Xu CQ Brône B Wicher D Bozkurt O Lu WY Huys I Han YH Tytgat J Van Kerkhove E Chi CW 《The Journal of biological chemistry》2004,279(33):34562-34569
BmBKTx1 is a novel short chain toxin purified from the venom of the Asian scorpion Buthus martensi Karsch. It is composed of 31 residues and is structurally related to SK toxins. However, when tested on the cloned rat SK2 channel, it only partially inhibited rSK2 currents, even at a concentration of 1 microm. To screen for other possible targets, BmBKTx1 was then tested on isolated metathoracic dorsal unpaired median neurons of Locusta migratoria, in which a wide variety of ion channels are expressed. The results suggested that BmBKTx1 could specifically block voltage-gated Ca(2+)-activated K(+) currents (BK-type). This was confirmed by testing the BmBKTx1 effect on the alpha subunits of BK channels of the cockroach (pSlo), fruit fly (dSlo), and human (hSlo), heterologously expressed in HEK293 cells. The IC(50) for channel blocking by BmBKTx1 was 82 nm for pSlo and 194 nm for dSlo. Interestingly, BmBKTx1 hardly affected hSlo currents, even at concentrations as high as 10 microm, suggesting that the toxin might be insect specific. In contrast to most other scorpion BK blockers that also act on the Kv1.3 channel, BmBKTx1 did not affect this channel as well as other Kv channels. These results show that BmBKTx1 is a novel kind of blocker of BK-type Ca(2+)-activated K(+) channels. As the first reported toxin active on the Drosophila Slo channel dSlo, it will also greatly facilitate studying the physiological role of BK channels in this model organism. 相似文献
998.
Expression vectors of human granulocyte colony stimulating factor (G-CSG) and long acting tissue plasminogen activator (La-tPA)
in mammary gland were constructed using promoters of mouse whey acid protein gene (WAP) and sheep β-lactoglobulin gene (BLG)
with sizes of 2.6 and 5 kb respectively. Two kinds of transgenic mice of G-CSF and La-tPA were produced with microinjection.
The expression of G-CSF and La-tPA was achieved in mammary glands of transgenic mice, respectively. In order to establish
dual transgenic mice of La-tPA /G-CSF, transgenic mice carrying G-CSF and La-tPA gene characterized with specific expression
in mammary gland were mated. La-tPA/G-CSF dual transgenic mice were screened out from the hybrid offspring by Once-PCR. The
co-expression of La-tPA and G-CSF in mammary gland of the dual transgenic mice was confirmed by the milk assayed and Northern
blot analysis. Some parameters about the dual transgenic mice indicated that there were fewer litters than that of normal
mice. The ratio of dual transgenes was 46.1% in F1 generation, and offspring’s sex ratio was normal. Hence a dual transgenic
mouse model was established for the study of co-expression foreign proteins in mammary gland. 相似文献
999.
1000.
无机元素对紫杉醇和紫杉烷类化合物生物合成的调控作用 总被引:13,自引:1,他引:13
利用细胞培养生产此杉醇是重要的生产途径之一,但是,由于紫杉醇含量低,已经成为世界级研究难题。因此,紫杉醇的生物合成调控成为研究热点。Mg^++有利于紫杉醇的合成,并促进10-去乙酰浆果赤霉素Ⅲ和浆果赤霉素Ⅲ向紫杉醇转化。Cu^++抑制紫杉醇及紫杉烷类化合物的合成。适量的Fe^++可以促进紫杉醇的合成,但较高或产低浓度的Fe^++均抑制10-去乙酰浆果赤霉素Ⅲ和浆果赤霉素Ⅲ向紫杉醇转化。 相似文献