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841.
842.
843.
Hye Jin Jung Pyo June Pak Sung Hyo Park Jae Eun Ju Joong-Su Kim Hoi-Seon Lee Namhyun Chung 《PloS one》2014,9(11)
Silver materials have been widely used in diverse fields. However, their toxicity and their mechanism, especially in different forms, have not been studied sufficiently. Thus, cytotoxicity, apoptosis, and interleukin-1beta (IL-1β) production were investigated using macrophage-like THP-1 cells in the presence of Ag microparticles (AgMPs, 2.7 µm), Ag submicroparticles (AgSMPs, 150 nm), and Ag wires (AgWs, 274 nm×5.3 µm). The levels of cytotoxicity, apoptosis, and IL-1β production by AgWs were higher than those by the other two AgSMPs and AgMPs. This trend was also observed with each step of the signaling mechanism for IL-1β production, which is a single pathway affiliated with ROS generation or lysosomal rupture or both, cathepsin B, caspase-1 (NALP3 inflammasome), and finally IL-1β production in THP-1 cells. All these results suggest that, for development of safe and effective silver materials, the shape or form of silver materials should be considered, especially for macrophage cell lines because epithelial cell lines are not overly sensitive to silver materials. 相似文献
844.
Juyeon Lee Boyeon Park Gayoung Kim Kwangwoo Kim Jeongjun Pak Kwanhyeong Kim Michael B. Ye Sung-Gyoo Park Daeho Park 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2014
Elmo is an evolutionarily conserved mammalian ortholog of Caenorhabditis elegans CED-12 with proposed roles during the removal of apoptotic cells, cell migration, neurite outgrowth, and myoblast fusion (Katoh and Negishi (2003) [1], Park and Tosello (2007) [2], Grimsley et al. (2004) [3], Hamoud et al. (2014) [4]). Elmo mediates these cellular processes by interacting with various proteins located in the plasma membrane, cytoplasm and nucleus, and by modulating their activities although it has no intrinsic catalytic activity (Park and Tosello (2007) [2], Hamoud et al. (2014) [4], Li et al. (2013) [5], Margaron, Fradet and Cote (2013) [6], and Mauldin et al. (2013)[7]). Because there are a limited number of proteins known to interact with Elmo, we performed a yeast two-hybrid screen using Elmo1 as bait to identify Elmo1-interacting proteins and to evaluate their mode of regulation. Arhgef16 was one of the proteins identified through the screen and subsequent analyses revealed that Arhgef16 interacted with Elmo1 in mammalian cells as well. Expression of Arhgef16 in phagocytes promoted engulfment of apoptotic cells, and engulfment mediated by Arhgef16 increased synergistically in the presence of Elmo1 but was abrogated in the absence of Elmo1. In addition, Arhgef16-mediated removal of apoptotic cells was dependent on RhoG, but independent of Dock1. Taken together, this study suggests that the newly identified Elmo1-interacting protein, Arhgef16, functions synergistically with Elmo1 to promote clearance of apoptotic cells in a RhoG-dependent and Dock1-independent manner. 相似文献
845.
Reza Malekzadeh‐Viayeh Razieh Pak‐Tarmani Nasim Rostamkhani Diego Fontaneto 《Zoological Journal of the Linnean Society》2014,170(2):233-244
Faunistic survey using a DNA taxonomy approach may provide different results from morphological methods, especially for small and understudied animals. In this study, we report the results from morphometric analyses (linear measurements of the lorica) and DNA taxonomy (generalized mixed Yule coalescent model on the barcoding mtDNA locus cytochrome c oxidase subunit I) performed on 15 clonal lineages of the rotifer Brachionus plicatilis species complex from six Iranian inland saltwaters. The DNA taxonomy approach found more units of diversity (four) than the morphometric approach (two) in the studied rotifers. Three of the taxa identified in this study are already known as described valid species or as‐yet unnamed lineages, but a new, additional lineage is also identified from Iran. © 2014 The Linnean Society of London 相似文献
846.
Haiqin Lu Hung-Tat Leung Ning Wang William L. Pak Bih-Hwa Shieh 《The Journal of biological chemistry》2009,284(17):11100-11109
Ca2+ modulates the visual response in both vertebrates and
invertebrates. In Drosophila photoreceptors, an increase of
cytoplasmic Ca2+ mimics light adaptation. Little is known regarding
the mechanism, however. We explored the role of the sole Drosophila
Ca2+/calmodulin-dependent protein kinase II (CaMKII) to mediate
light adaptation. CaMKII has been implicated in the phosphorylation of
arrestin 2 (Arr2). However, the functional significance of Arr2
phosphorylation remains debatable. We identified retinal CaMKII by anti-CaMKII
antibodies and by its Ca2+-dependent autophosphorylation. Moreover,
we show that phosphorylation of CaMKII is greatly enhanced by okadaic acid,
and indeed, purified PP2A catalyzes the dephosphorylation of CaMKII.
Significantly, we demonstrate that anti-CaMKII antibodies
co-immunoprecipitate, and CaMKII fusion proteins pull down the catalytic
subunit of PP2A from fly extracts, indicating that PP2A interacts with CaMKII
to form a protein complex. To investigate the function of CaMKII in
photoreceptors, we show that suppression of CaMKII in transgenic flies affects
light adaptation and increases prolonged depolarizing afterpotential
amplitude, whereas a reduced PP2A activity brings about reduced prolonged
depolarizing afterpotential amplitude. Taken together, we conclude that CaMKII
is involved in the negative regulation of the visual response affecting light
adaptation, possibly by catalyzing phosphorylation of Arr2. Moreover, the
CaMKII activity appears tightly regulated by the co-localized PP2A.Visual transduction is the process that converts the signal of light
(photons) into a change of membrane potential in photoreceptors (see Ref.
1 for review). Visual signaling
is initiated upon the activation of rhodopsins by light: light switches on
rhodopsin to generate metarhodopsin, which activates the heterotrimeric
Gq in Drosophila
(2). Subsequently, the
GTP-bound Gαq subunit activates phospholipase Cβ4
encoded by the norpA (no receptor
potential A) gene
(3). Phospholipase Cβ4
catalyzes the breakdown of phosphoinositol 4,5-bisphosphate to generate
diacylglycerol, which or its metabolite has been implicated in gating the
transient receptor potential
(TRP)2 and TRP-like
channels (4,
5). TRP is the major
Ca2+ channel that mediates the light-dependent depolarization
response leading to an increase of cytosolic Ca2+ in
photoreceptors. The rise of intracellular Ca2+ modulates several
aspects of the visual response including activation, deactivation, and light
adaptation (6). For example,
Ca2+ together with diacylglycerol activates a classical protein
kinase C, eye-PKC, which is critical for the negative regulation of visual
signaling by modulating deactivation and light adaptation
(7–11).Light adaptation is the process by which photoreceptors adjust the visual
sensitivity in response to ambient background light by down-regulating
rhodopsin-mediated signaling. Light adaptation can be arbitrarily subdivided
into long term and short term adaptation and may involve multiple regulations
to reduce the efficiency of rhodopsin, G protein, or cation channels. For
example, translocation of both Gq
(12,
13) and TRP-like channels
(14,
15) out of the visual
organelle may contribute to long term adaptation in Drosophila. In
contrast, short term adaptation may be orchestrated by modulating the activity
of signaling proteins by protein kinases. Hardie and co-workers
(16) demonstrated that an
increase of cytoplasmic [Ca2+] mimicked light adaptation, leading
to inhibition of the light-induced current. These authors also showed that
light adaptation is independent of eye-PKC. Thus the effect of cytoplasmic
Ca2+ to control light adaptation is likely mediated via calmodulin
and CaMKII. The contribution of CaMKII to light adaptation has not been
explored.CaMKII is a multimeric Ca2+/calmodulin-dependent protein kinase
that modulates diverse signaling processes
(17). Drosophila
contains one CaMKII gene (18)
that gives rise to at least four protein isoforms
(19). These CaMKII isoforms
share over 85% sequence identities with the α isoform of vertebrate
CaMKII. For insights into the in vivo physiological role of CaMKII,
Griffith et al. (20)
generated transgenic flies (ala) expressing an inhibitory domain of
the rat CaMKII under the control of a heat shock promoter, hsp70.
They demonstrated that, upon heat shock treatment, the overexpression of the
inhibitory peptide resulted in a suppression of the endogenous CaMKII activity
in the transgenic flies (20).
It has been shown that inhibition of CaMKII affects learning and memory
(20) and neuronal functions
(21–24).
In photoreceptors, CaMKII has been implicated in the phosphorylation of the
major visual arrestin, Arr2
(25,
26). However, how
phosphorylation of Arr2 by CaMKII modifies the visual signaling remains to be
elucidated.Here we report the biochemical and electrophysiological analyses of CaMKII
in Drosophila retina. We demonstrate that suppression of CaMKII in
ala1 transgenic flies leads to a phenotype indicative of
defective light adaptation. The ala1 flies also display
greater visual response, suggesting a defect in Arr2. These results support
the notion that CaMKII plays a role in the negative regulation of the visual
response. Our biochemical analyses demonstrate that dephosphorylation of
CaMKII is mediated by protein phosphatase 2A (PP2A). Importantly, we show that
PP2A interacts with CaMKII, indicating that CaMKII forms a stable protein
complex with PP2A to ensure a tight regulation of the kinase activity. Thus a
partial loss of function in PP2A would elevate the CaMKII activity. Indeed, we
show that mts heterozygotes display reduced prolonged depolarizing
potential (PDA) amplitude. This PDA phenotype strongly suggests that Arr2
becomes more effective to terminate the visual signaling in mts
flies. Together, our findings indicate that the ability of Arr2 to terminate
metarhodopsin is increased upon phosphorylation by CaMKII, and the retinal
CaMKII activity is regulated by PP2A. 相似文献
847.
Clinical evaluation of micro-scale chip-based PCR system for rapid detection of hepatitis B virus 总被引:1,自引:0,他引:1
Cho YK Kim J Lee Y Kim YA Namkoong K Lim H Oh KW Kim S Han J Park C Pak YE Ki CS Choi JR Myeong HK Ko C 《Biosensors & bioelectronics》2006,21(11):2161-2169
The polymerase chain reaction (PCR) is widely used to amplify a small amount of DNA in samples for genetic analysis. Rapid and accurate amplification is prerequisite for broad applications including molecular diagnostics of diseases, food safety, and biological warfare tests. We have developed a rapid real-time micro-scale chip-based PCR system, which consists of six individual thermal cycling modules capable of independent control of PCR protocols. The PCR volume is 1 microl and it takes less than 20 min to complete 40 thermal cycles. To test utility of a chip-based PCR system as a molecular diagnostic device, we have conducted the first large-scale clinical evaluation study. Three independent clinical evaluation studies (n = 563) for screening the hepatitis B virus (HBV) infection, the most popular social epidemic disease in Asia, showed an excellent sensitivity, e.g. 94%, and specificity, e.g. 93%, demonstrating micro-scale chip-based PCR can be applied in molecular diagnostics. 相似文献
848.
Evgenia Markova Vasily Malygin Sophie Montuire Adam Nadachowski Jean-Pierre Quéré Katarzyna Ochman 《Journal of Mammalian Evolution》2010,17(2):121-139
The data on dental variability in natural populations of sibling species of common voles (“arvalis” group, genus Microtus) from European and Asian parts of the species’ ranges are summarized using a morphotype-based approach to analysis of dentition.
Frequency distributions of the first lower (m1) and the third upper (M3) molar morphotypes are analyzed in about 65 samples
of M. rossiaemeridionalis and M. arvalis represented by arvalis and obscurus karyotypic forms. Because of extreme similarity of morphotype dental patterns in the
taxa studied, it is impossible to use molar morphotype frequencies for species identification. However, a morphotype-based
approach to analysis of dental variability does allow analysis of inter-species comparisons from an evolutionary standpoint.
Three patterns of dental complexity are established in the taxa studied: simple, basic (the most typical within the ranges
of both species), and complex. In M. rossiaemeridionalis and in M. arvalis obscurus only the basic pattern of dentition occurs. In M. arvalis arvalis, both simple and basic dental patterns are found. Analysis of association of morphotype dental patterns with geographical
and environmental variables reveals an increase in the number of complex molars with longitude and latitude: in M. arvalis the pattern of molar complication is more strongly related to longitude, and in M. rossiaemeridionalis—to latitude. Significant decrease in incidence of simple molars with climate continentality and increasing aridity is found
in M. arvalis. The simple pattern of dentition is found in M. arvalis arvalis in Spain, along the Atlantic coast of France and on islands thereabout, in northeastern Germany and Kirov region
in European Russia. Hypotheses to explain the distribution of populations with different dental patterns within the range
of M. arvalis sensu stricto are discussed. 相似文献
849.
Chukwuemeka Louis Ajonuma Lam Kin Fok Sze Lok Ho Sheung Kay Paul Chan Pak H. Chow Ling Lai Tsang Yan Hau Connie Wong Jie Chen Shen Li Kenneth Dewi Rowlands Wa Yiu Chung Chang Hsiao Chan 《Cell biology international》2010,34(6):593-600
Chlamydia trachomatis is an obligate intracellular Gram‐negative pathogen affecting over 600 million people worldwide with 92 million new cases occurring globally each year. C. trachomatis enter the cells and replicate to infect different tissues/organs, giving rise to a spectrum of pathological conditions; however, the exact mechanism or receptor(s) for their entry is not well understood. Here we report that CFTR (cystic fibrosis transmembrane conductance regulator), an apical epithelial anion channel, is required for cellular entry and internalization of C. trachomatis. Human epithelial cell lines expressing functional CFTR internalized more C. trachomatis than the cells expressing mutant Δ508 CFTR. The in vitro cellular uptake of C. trachomatis can be blocked by CFTR inhibitors or antibody, and the in vivo cellular uptake of C. trachomatis in CFTR mutant (CFTR?/?) mice was significantly less compared with that in the wild‐type. Direct interaction between CFTR and C. trachomatis LPS (lipopolysaccharide) is demonstrated by their immune‐co‐localization and co‐immunoprecipitation. Despite an increase in CFTR expression observed upon C. trachomatis LPS challenge, a reduction in its ion channel activity is observed, consistent with the notion that CFTR functions as a receptor for cellular entry and internationization of C. trachomatis, with compromised ion‐channel function. These findings, for the first time, demonstrate that CFTR functions as a cell‐surface receptor for epithelial cell entry, and internalization of C. trachomatis and these findings may lead to the development of new treatment strategies to curtail the spread of chlamydial infections. 相似文献
850.
Podbilewicz B Leikina E Sapir A Valansi C Suissa M Shemer G Chernomordik LV 《Developmental cell》2006,11(4):471-481
During cell-cell fusion, two cells' plasma membranes merge, allowing the cytoplasms to mix and form a syncytium. Little is known about the mechanisms of cell fusion. Here, we asked whether eff-1, shown previously to be essential for fusion in Caenorhabditis elegans, acts directly in the fusion machinery. We show that expression of EFF-1 transmembrane protein drives fusion of heterologous cells into multinucleate syncytia. We obtained evidence that EFF-1-mediated fusion involves a hemifusion intermediate characterized by membrane mixing without cytoplasm mixing. Furthermore, syncytiogenesis requires EFF-1 in both fusing cells. To test whether this mechanism also applies in vivo, we conducted genetic mosaic analysis of C. elegans and found that homotypic epidermal fusion requires EFF-1 in both cells. Thus, although EFF-1-mediated fusion shares characteristics with viral and intracellular fusion, including an apparent hemifusion step, it differs from these reactions in the homotypic organization of the fusion machinery. 相似文献