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991.
992.
Wei Zhou Jianyi Zhu Songdong Shen Shan Lu Jinfeng Wang Jianrong Xu Pu Xu 《Journal of applied phycology》2008,20(5):991-999
Nuclear divisions of carpospores, conchocelis and conchospores of Porphyra yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia from China were investigated. The observations showed diploid chromosome numbers of 2n = 6 for P. yezoensis and P. oligospermatangia, and 2n = 10 for P. haitanensis and P. katadai var. hemiphylla. For all four species, somatic pairing of chromosome sets was observed in late prophase. Sister chromosomes separated at
anaphase as mitosis took place in carpospores, conchocelis filamentous cells, conchosporangial branch cells and sporangial
cells (conchospore formation). Chromosome configurations of tetrad and ring-shaped in conchospore germination were observed,
demonstrating the occurrence of meiosis. The characteristics of diploid nuclear division in 2n = 6 species are the same as
those of 2n = 10 species. The influence of somatic pairing on nuclear division of diploid cells in Porphyra was discussed. 相似文献
993.
Jiazhang Lian Shinghua Ding Jin Cai Danping Zhang Zhinan Xu Xiaoning Wang 《Applied microbiology and biotechnology》2009,82(3):463-470
Aquaporin Z (AqpZ), a typical orthodox aquaporin with six transmembrane domains, was expressed as a fusion protein with TrxA
in E. coli in our previous work. In the present study, three fusion partners (DsbA, GST and MBP) were employed to improve the expression
level of this channel protein in E. coli. The result showed that, compared with the expression level of TrxA-AqpZ, five- to 40-fold increase in the productivity of
AqpZ with fusion proteins was achieved by employing these different fusion partners, and MBP was the most efficient fusion
partner to increase the expression level. By using E. coli C43 (DE3)/pMAL-AqpZ, the effects of different expression conditions were investigated systematically to improve the expression
level of MBP-AqpZ in E. coli. The high productivity of MBP-AqpZ (200 mg/l) was achieved under optimized conditions. The present work provides a novel
approach to improve the expression level of membrane proteins in E. coli. 相似文献
994.
Dafne Italiano Anna Maria Lena Gerry Melino Eleonora Candi 《Cell cycle (Georgetown, Tex.)》2012,11(24):4589-4596
Analysis of microarrays performed in p53-, TAp63α- and ΔNp63α-inducible SaOs-2 cell lines allowed the identification of NCF2 mRNA upregulation in response to p53 induction. NCF2 gene encodes for p67phox, the cytosolic subunit of the NADPH oxidase enzyme complex. The recruitment of p67phox to the cell membrane causes the activation of the NADPH oxidase complex followed by the generation of NADP+ and superoxide from molecular oxygen. The presence of three putative p53 binding sites on the NCF2 promoter was predicted, and the subsequent luciferase and chromatin immunoprecipitation assays showed the activation of NCF2 promoter by p53 and its direct binding in vivo to at least one of the sites, thus confirming the hypothesis. NCF2 upregulation was also confirmed by real-time PCR in several cell lines after p53 activation. NCF2 knockdown by siRNA results in a significant reduction of ROS production and stimulates cell death, suggesting a protective function of Nox2-generated ROS in cells against apoptosis. These results provide insight into the redox-sensitive signaling mechanism that mediates cell survival involving p53 and its novel target NCF2/p67phox. 相似文献
995.
Neurovascular injury comprises a wide spectrum of pathophysiology that underlies the progression of brain injury after cerebral
ischemia. Recently, it has been shown that activation of the integrin-associated protein CD47 mediates the development of
blood–brain barrier injury and edema after cerebral ischemia. However, the mechanisms that mediate these complex neurovascular
effects of CD47 remain to be elucidated. Here, we compare the effects of CD47 signaling in brain endothelial cells, astrocytes,
and pericytes. Exposure to 4N1 K, a specific CD47-activating peptide derived from the major CD47 ligand thrombospondin-1,
upregulated two major neurovascular mediators, vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9),
in brain endothelial cells and astrocytes. No changes were detected in pericytes. These findings may provide a potential mechanism
for CD47-induced changes in blood–brain barrier homeostasis, and further suggest that CD47 may be a relevant neurovascular
target in stroke. 相似文献
996.
997.
A systematic comparison of 4-[18F]fluorobenzaldehyde-O-(2-{2-[2-(pyrrol-2,5-dione-1-yl)ethoxy]-ethoxy}-ethyl)oxime ([18F]FBOM) and 4-[18F]fluorobenzaldehyde-O-[6-(2,5-dioxo-2,5-dihydro-pyrrol-1-yl)-hexyl]oxime ([18F]FBAM) as prosthetic groups for the mild and efficient 18F labeling of cysteine-containing peptides and proteins with the amine-group reactive acylation agent, succinimidyl-4-[18F]fluorobenzoate ([18F]SFB), is described. All three prosthetic groups were prepared in a remotely controlled synthesis module. Synthesis of [18F]FBOM and [18F]FBAM was accomplished via oxime formation through reaction of appropriate aminooxy-functionalized labeling precursors with
4-[18F]fluorobenzaldehyde. The obtained radiochemical yields were 19% ([18F]FBOM) and 29% ([18F]FBAM), respectively. Radiolabeling involving [18F]FBAM and [18F]FBOM was exemplified by the reaction with cysteine-containing tripeptide glutathione (GSH), a cysteine-containing dimeric
neurotensin derivative, and human native low-density lipoprotein (nLDL) as model compounds. Radiolabeling with the acylation
agent [18F]SFB was carried out using a dimeric neurotensin derivative and nLDL. Both thiol-group reactive prosthetic groups show significantly
better labeling efficiencies for the peptides in comparison with the acylation agent [18F]SFB. The obtained results demonstrate that [18F]FBOM is especially suited for the labeling of hydrophilic cysteine-containing peptides, whereas [18F]FBAM shows superior labeling performance for higher molecular weight compounds as exemplified for nLDL apolipoprotein constituents.
However, the acylation agent [18F]SFB is the preferred prosthetic group for labeling nLDL under physiological conditions. 相似文献
998.
999.
1000.