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941.
小牛类表皮生长因子活性肽(c-EGF)的分离纯化及性质 总被引:1,自引:0,他引:1
本文报道小牛颌下腺通过酸抽提、CM52、DE52柱层析、SephadexG75凝胶过滤及HPLC等步,分离纯化到一个分子量为6kD,等电点为4.6的小肽。该小肽类似人重组表皮生长因子(rh—EGF)的生物活性,具有刺激NRK细胞的增殖及刺激新生小鼠的睁眼、萌牙,并具有增加A431细胞膜蛋白质磷酸化的功能。氨基酸组成缺少苯丙氨酸及苏氨酸残基。我们命名它为小牛类EGF样活性肽(calfEGF-likeactivepeptide,简称c-EGF)。 相似文献
942.
Recombinant human pigment epithelium-derived factor (PEDF): characterization of PEDF overexpressed and secreted by eukaryotic cells. 总被引:1,自引:0,他引:1 下载免费PDF全文
E. Stratikos E. Alberdi P. G. Gettins S. P. Becerra 《Protein science : a publication of the Protein Society》1996,5(12):2575-2582
Pigment epithelium-derived factor (PEDF) is a serpin found in the interphotoreceptor matrix of the eye, which, although not a proteinase inhibitor, possesses a number of important biological properties, including promotion of neurite outgrowth and differential expression in quiescent versus senescent states of certain cell types. The low amounts present in the eye, together with the impracticality of using the eye as a source for isolation of the human protein, make it important to establish a system for overexpression of the recombinant protein for biochemical and biological studies. We describe here the expression and secretion of full-length glycosylated human recombinant PEDF at high levels (> 20 micrograms/ mL) into the growth medium of baby hamster kidney cells and characterization of the purified rPEDF by circular dichroism and fluorescence spectroscopies and neurite outgrowth assay. By these assays, the recombinant protein behaves as expected for a correctly folded full-length human PEDF. The availability of milligram amounts of PEDF has permitted quantitation of its heparin binding properties and of the effect of reactive center cleavage on the stability of PEDF towards thermal and guanidine hydrochloride denaturation. 相似文献
943.
Marcelo Cecim Maria Alvarez-Sanz Louis van de Kar Sterling Milton Andrzej Bartke 《Transgenic research》1996,5(3):187-192
Previous work from our laboratory provided evidence for increased plasma corticosterone levels in mice transgenic for human and bovine growth hormone (GH). Corticosterone was elevated in both sexes, under both basal and ether-induced stress conditions. The objectives of the present study were to investigate thein vitro adrenal sensitivity to ACTH, GH and/or IGF-I in normal and bGH transgenic mice, to examine plasma corticosterone levels at different times of the day, and to determine plasma levels of ACTH in these animals. For the measurement of plasma corticosterone and ACTH levels, transgenic and normal siblings were housed 2 per cage and decapitated simultaneously within 20 seconds of the first disturbance of the cage. The corticosterone production byin vitro adrenal incubations did not differ between adrenals from normal and transgenic mice at the basal level or in the presence of different doses of ACTH. Growth hormone or IGF-I did not have any effect on corticosterone productionin vitro when given alone, and did not modify the effects of ACTH on the accumulation of corticosterone in the media. Plasma corticosterone concentrations were higher in transgenic than in normal animals in both morning and evening. Plasma concentrations of ACTH in animals killed in the morning were sharply increased in transgenic males as compared with their normal siblings. The results indicate that increased circulating levels of corticosterone in transgenic mice are not due to a potentiation of ACTH actions by GH or IGF-I, but rather to a chronic increase in plasma ACTH levels. The increase in ACTH is presumably a reflection of GH actions in the hypothalamic-pituitary system. 相似文献
944.
945.
A genetic approach to the understanding of tree architecture is to cross trees of contrasting features and to study their
segregating F2 progenies. For this purpose, members of a 3-generation pedigree, combining Populus trichocarpa, P. deltoides, and their F1 and F2 offspring, were grown side by side in a clonally replicated plantation. At 2 and 3 years of growth, tree architecture was
analyzed at the stem, branch, and leaf levels. In all generations, proleptic branches were more numerous, longer, and had
more and larger leaves than sylleptics initiated in the same year. The analysis of variance revealed significant genotypic
effects on growth, branch and leaf biometrics in the F2 family, with broad-sense heritabilities (H2) ranging from 0.50 to 0.80 for most traits. For branch and leaf traits, the H2 values were found to vary among branch types and crown positions. In year 2, the degree of genetic control was stronger for
sylleptics than proleptics and for upper than lower crown positions. These patterns were followed in year 3, except that H2 values were more a function of position within crown, as a consequence of increased competition among trees. The genetic
correlations between branch/leaf morphology and stem growth were also a function of branch type and crown position. Generally,
traits on proleptics or at upper positions were more tightly correlated with height growth, whereas those on sylleptics or
at lower positions, with basal area growth. By year 3, proleptic traits showed increased genetic correlations with both height
and radial growth. The implications of these results for the construction of ideotypes are discussed.
Received: 1 December 1995 相似文献
946.
Deborah M. Briercheck Timothy J. Allison John P. Richardson Jeffery F. Ellena Todd C. Wood Gordon S. Rule 《Journal of biomolecular NMR》1996,8(4):429-444
Summary Protein fragments containing the RNA-binding domain of Escherichia coli rho protein have been over-expressed in E. coli. NMR spectra of the fragment containing residues 1–116 of rho protein (Rho116) show that a region of this protein is unfolded in solution. Addition of (dC)10 to this fragment stabilizes the folded form of the protein. The fragment comprising residues 1–130 of rho protein (Rho130) is found to be stably folded, both in the absence and presence of nucleic acid. NMR studies of the complex of Rho 130 with RNA and DNA oligonucleotides indicate that the binding-site size, affinity, and specificity of Rho 130 are similar to those of intact rho protein; therefore, Rho 130 is a suitable model of the RNA-binding domain of rho protein. NMR line widths as well as titration experiments of Rho130 complexed with oligonucleotides of various lengths suggest that Rho130 forms oligomers in the presence of longer oligonucleotides. 1H, 15N and 13C resonance assignments were facilitated by the utilization of two pulse sequences, CN-NOESY and CCH-TOCSY. The secondary structure of unliganded Rho130 has been determined by NMR techniques, and it is clear that the RNA-binding domain of rho is more structurally similar to the cold shock domain than to the RNA recognition motif.Abbreviations Rho116, Rho130
protein containing the first 116 (130) residues of rho
- CSD
cold shock domain
- RRM
RNA recognition motif
- RBD
RNA-binding domain
- IPTG
isopropyl -D-thiogalactopyranoside
- EDTA
ethylenediaminetetraacetic acid
- NOE
nuclear Overhauser enhancement 相似文献
947.
鱼腥藻1017株的混合营养型生长 总被引:9,自引:1,他引:8
鱼腥藻1017株混合营养型生长有其特点,外源葡萄糖对生长的刺激不仅在低光强(800lx),而且在高光强(7000lx)也表现出来。其混合营养型生长速率在800-7000lx范围内随光照强度的增加而增加,在葡萄糖浓度5-20mmol/L范围内随外源葡萄糖浓度增加而增加。鱼腥藻1017株混合营养型生长与光能自养生长相比,生长速率明显提高,对数生长期延长,收获物浓度显著增高,生物量显著提高。 相似文献
948.
949.
水稻器官干物质运转特性的因子分析 总被引:3,自引:0,他引:3
本文对33个水稻品种(组合)5个器官的干物质转运率和移动率(共10个性状)进行了因子分析,结果表明,5个器官的干物质运转特性均可自成主因子,均具有重要作用,主因子1为茎杆运转因子,主因子2为叶片运转因子,主因子3为功能叶片运转因子,主因子4为功能叶外其它叶片运转因子,主因子5为叶鞘运转因子.除主因子1具有较大的方差贡献外,其余主因子方差贡献接近.杂交F1比常规品种具有更大的主因子l得分,部分常规品种也具有较高的主因子l得分,可作为亲本加以利用. 相似文献
950.
将人粒细胞-巨噬细胞集落刺激因子(GM-CSF)和人血清白蛋白第三功能区(HAS-D3)的基因串联后,在E.coli中获高效表达,表达量占菌体蛋白的32.6%.利用TF-1体外细胞活性测定表明,GM-HSA的活性单位为1.04×10~6U/mg,虽然其比活性低于GM-CSF,但比后者具有更高的体外热稳定性和储藏稳定性. 相似文献