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851.
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Cheung CY Webb SE Love DR Miller AL 《The International journal of developmental biology》2011,55(2):153-174
Intact zebrafish embryos were used as an in vivo animal model to investigate the role of Ca2+ signaling during the differentiation of slow muscle cells (SMCs) within forming skeletal muscle. Transgenic zebrafish were generated using an a-actin promoter that targeted apoaequorin expression specifically to muscle cells. Two distinct Ca2+ signaling periods (CSPs) were visualized in the developing SMCs: between ~17.5-19.5 hours post-fertilization (hpf) and after ~23 hpf, separated by a ~3.5 h Ca2+ signaling quiet period. Further spatial characterization of these Ca2+ signals using confocal fluorescent microscopy and calcium green-1 dextran as a reporter, indicated that the earlier CSP displayed distinct nuclear and cytoplasmic components, whereas the later CSP was predominantly cytoplasmic. Both CSPs consisted of a series of oscillating Ca2+ waves generated at distinct frequencies, while the earlier CSP also displayed a slow rise then fall in the Ca2+ baseline-level. Imaging of cyclopamine- and forskolin-treated wild-type, or smo-/- mutant embryos, where SMCs do not form, confirmed the specific cell population generating the signals. Treating embryos with antagonists indicated that both IP3Rs and RyRs are responsible for generating the temporal characteristics of the Ca2+ signaling signature, and that the latter plays a necessary role in SMC differentiation and subsequent myotome patterning. Together, these data support and extend the proposition that specific spatiotemporal patterns of spontaneous Ca2+ signals might be used for different as well as combinatorial regulation of both nuclear and cytosolic signal transduction cascades, resulting in myofibrillogenesis in SMCs as well as myotome patterning. 相似文献
854.
VH4 gene segments dominate the intrathecal humoral immune response in multiple sclerosis 总被引:1,自引:0,他引:1
Owens GP Winges KM Ritchie AM Edwards S Burgoon MP Lehnhoff L Nielsen K Corboy J Gilden DH Bennett JL 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(9):6343-6351
A characteristic feature of the CNS inflammatory response in multiple sclerosis (MS) is the intrathecal synthesis of IgG and the presence of oligoclonal bands. A strong correlation between CD138(+) plasma blast numbers in MS cerebrospinal fluid (CeSF) and intrathecal IgG synthesis suggests that these cells are the major Ab-secreting cell type in MS CeSF. Sequencing of V regions from CD138(+) cells in MS CeSF has revealed somatically mutated and expanded IgG clonotypes consistent with an Ag-targeted response. In the present study, single-cell RT-PCR analysis of CD138(+) cells from 11 MS patients representing differing clinical courses and stages of disease identified expansion of CD138(+) cells with functionally rearranged V(H)4 gene segments as an overriding feature of MS CeSF repertoires. V(H)4 dominance was attributed to the preferential selection of specific V(H)4 genes, particularly gene segment V(H)4-39, which displayed a significant enrichment in CeSF compared with MS peripheral blood B cells. A modest increase in V(H)4 prevalence among MS peripheral blood IgG memory cells was also noted, suggesting that factors shaping the CD138 repertoire in CeSF might also influence the peripheral IgG memory cell pool. These results indicate a highly restricted B cell response in MS. Identifying the targets of CeSF plasma cells may yield insights into disease pathogenesis. 相似文献
855.
856.
Alkylpurine–DNA–N-Glycosylase Knockout Mice Show Increased Susceptibility to Induction of Mutations by Methyl Methanesulfonate 下载免费PDF全文
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858.
Donald Greiff 《Applied microbiology》1969,18(1):130
A simple, safe, closed system for opening evacuated, sealed glass ampoules and removing dried pathogens is described. 相似文献
859.
John A.M. Ramshaw Derek Peacock Barry T. Meatyard Donald Boulter 《Phytochemistry》1974,13(12):2783-2789
The amino acid sequence of Epiteromorpha cytochrome c has been added to an affinity tree relating the cytochrome c sequences of animals, plants, fungi, protozoans and one bacterium, cytochrome c2 from Rhodospirillum. The Enteromorpha sequence lies on the line of descent of the higher plant sequences; it is not closely related to the cytochrome c of the photosynthetic protozoan, Euglena. The distribution of ε-N-trimethyllysine in cytochrome c is discussed. 相似文献
860.
Moeder W Barry CS Tauriainen AA Betz C Tuomainen J Utriainen M Grierson D Sandermann H Langebartels C Kangasjärvi J 《Plant physiology》2002,130(4):1918-1926
We show that above a certain threshold concentration, ozone leads to leaf injury in tomato (Lycopersicon esculentum). Ozone-induced leaf damage was preceded by a rapid increase in 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity, ACC content, and ethylene emission. Changes in mRNA levels of specific ACC synthase, ACC oxidase, and ethylene receptor genes occurred within 1 to 5 h. Expression of the genes encoding components of ethylene biosynthesis and perception, and biochemistry of ethylene synthesis suggested that ozone-induced ethylene synthesis in tomato is under biphasic control. In transgenic plants containing an LE-ACO1 promoter-beta-glucuronidase fusion construct, beta-glucuronidase activity increased rapidly at the beginning of the O(3) exposure and had a spatial distribution resembling the pattern of extracellular H(2)O(2) production at 7 h, which coincided with the cell death pattern after 24 h. Ethylene synthesis and perception were required for active H(2)O(2) production and cell death resulting in visible tissue damage. The results demonstrate a selective ozone response of ethylene biosynthetic genes and suggest a role for ethylene, in combination with the burst of H(2)O(2) production, in regulating the spread of cell death. 相似文献