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991.
Background
Babesia bovis is an apicomplexan intraerythrocytic protozoan parasite that induces babesiosis in cattle after transmission by ticks. During specific stages of the apicomplexan parasite lifecycle, such as the sporozoites of Plasmodium falciparum and tachyzoites of Toxoplasma gondii, host cells are targeted for invasion using a unique, active process termed “gliding motility”. However, it is not thoroughly understood how the merozoites of B. bovis target and invade host red blood cells (RBCs), and gliding motility has so far not been observed in the parasite.Methodology/Principal Findings
Gliding motility of B. bovis merozoites was revealed by time-lapse video microscopy. The recorded images revealed that the process included egress of the merozoites from the infected RBC, gliding motility, and subsequent invasion into new RBCs. The gliding motility of B. bovis merozoites was similar to the helical gliding of Toxoplasma tachyzoites. The trails left by the merozoites were detected by indirect immunofluorescence assay using antiserum against B. bovis merozoite surface antigen 1. Inhibition of gliding motility by actin filament polymerization or depolymerization indicated that the gliding motility was driven by actomyosin dependent process. In addition, we revealed the timing of breakdown of the parasitophorous vacuole. Time-lapse image analysis of membrane-stained bovine RBCs showed formation and breakdown of the parasitophorous vacuole within ten minutes of invasion.Conclusions/Significance
This is the first report of the gliding motility of B. bovis. Since merozoites of Plasmodium parasites do not glide on a substrate, the gliding motility of B. bovis merozoites is a notable finding. 相似文献992.
Both growth and migratory history of the Pacific Ocean forms of the threespine stickleback Gasterosteus aculeatus collected in Otsuchi Bay, northeastern Japan, were examined using otolith microstructure and analysis of strontium (Sr) and
calcium (Ca) concentrations with wavelength dispersive X-ray spectrometry by an electron microprobe. Age of the juveniles
(21.6–25.9 mm in total length) examined ranged from 101 to 128 days (115 ± 8.5 days; mean ± SD), hatching being estimated
as having occurred between March and April 2001. The Sr : Ca ratios in the otoliths changed with both ontogenic development
and salinity of the habitat. The otolith Sr : Ca ratios increased gradually from 4.1 × 10−3 around the core to 7.5 × 10−3 around the edge of the otolith. The fluctuation pattern of otolith Sr : Ca ratios was different from those observed in both
freshwater resident and anadromous forms in previous studies. These results suggested that the fish sampled spend their lives
in the estuarine and sea environment without freshwater life after hatching.
Received: June 5, 2002 / Revised: September 11, 2002 / Accepted: September 24, 2002
Acknowledgments We thank Mr. K. Morita and crews of the Otsuchi Marine Research Center, Ocean Research Institute, The University of Tokyo
for their assistance in collecting specimens. This work was supported in part by Grant-in-Aid No. 13760138 from the Ministry
of Education, Culture, Sports, Science and Technology, Japan.
Correspondence to:Takaomi Arai 相似文献
993.
Iwabu Y Mizuta H Kawase M Kameoka M Goto T Ikuta K 《Microbes and infection / Institut Pasteur》2008,10(5):504-513
Superinfection rates of human immunodeficiency virus type 1 (HIV-1) have increasingly been leading to more variation in HIV-1, as evidenced by the emergence of circulating recombinant forms (CRFs). We recently reported complementation in a persistently replication-defective subtype B-infected cell clone, L-2, by superinfection with CRF15_01B. The L-2 cells continuously produce immature particles due to a one-base insertion at pol protease. Proviruses in the superinfected cells carried both subtypes and produced particles with a mature morphology. In this study, we examined possible recombination following complementation to generate replication-competent variants by using three cell clones prepared from superinfected L-2 cells. The individual clones predominantly expressed the initial subtype B-derived mature Gag proteins. However, the viral particles carried both subtype B with the mutation and wild-type CRF15_01B at pol, suggesting the generation of virions with heterozygous RNAs. Interestingly, with cell-free passages of the progeny, defective particles disappeared, and were replaced with heterogeneous recombinants in the pol region with sequences derived from CRF15_01B that expressed subtype B phenotype. Thus, even a defective form of persistent HIV-1 can become replication-competent through superinfection-mediated complementation followed by recombination. These findings suggest the significance of long-lived infected cells as recipients for superinfection. 相似文献
994.
Kimiko Takahashi Yoshio Sawasaki Jun-Ichi Hata Kiyoshi Mukai Tamotsu Goto 《In vitro cellular & developmental biology. Plant》1990,26(3):265-274
Summary A new cell line from the human umbilical vein has been established and maintained for more than 5 yr (180 generations; 900
population doublings). This strain, designated ECV304, is characterized by a cobblestone monolayer growth pattern, high proliferative
potential without any specific growth factor requirement, and anchorage dependency with contact inhibition. Karyotype analysis
of this cell line reveals it to be of human chromosomal constitution with a high trisomic karyotype (mode 80). Ultrastructurally,
endothelium-specific Weibel-Palade bodies were identified. Although one of the endothelial cell markers, Factor VIII-related
antigen (VIIIR:Ag) was negative in this cell line, immunocytochemical staining for the lectin Ulex europaeus I (UEA-I), and
PHM5 (anti-human endothelium as well as glomerular epithelium monoclonal antibody) was positive, and angiotensin-converting
enzyme (ACE) activity was also demonstrated. In addition, ECV304 displayed negativity for alkaline and acid phosphatase and
for the epithelial marker keratin. All of these findings suggest that ECV304 cells originated from umbilical vein endothelial
cells by spontaneous transformation. Ultrastructurally, no viruslike particles have been detected intracellularly. Nude mouse
tumorigenicity and rabbit cornea tests were both positive. This is a report on a novel case of phenotypic alteration of normal
venous endothelial cells of human origin in vitro, and generation of a transformant with indefinite life spans. This line
may be useful in studies of some physiologically active factors available for medical use. 相似文献
995.
Shigemoto Fujii Tomohiro Sawa Hideshi Ihara Kit I. Tong Tomoaki Ida Tatsuya Okamoto Ahmed Khandaker Ahtesham Yu Ishima Hozumi Motohashi Masayuki Yamamoto Takaaki Akaike 《The Journal of biological chemistry》2010,285(31):23970-23984
A nitrated guanine nucleotide, 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP), is formed via nitric oxide (NO) and causes protein S-guanylation. However, intracellular 8-nitro-cGMP levels and mechanisms of formation of 8-nitro-cGMP and S-guanylation are yet to be identified. In this study, we precisely quantified NO-dependent formation of 8-nitro-cGMP in C6 glioma cells via liquid chromatography-tandem mass spectrometry. Treatment of cells with S-nitroso-N-acetylpenicillamine led to a rapid, transient increase in cGMP, after which 8-nitro-cGMP increased linearly up to a peak value comparable with that of cGMP at 24 h and declined thereafter. Markedly high levels (>40 μm) of 8-nitro-cGMP were also evident in C6 cells that had been stimulated to express inducible NO synthase with excessive NO production. The amount of 8-nitro-cGMP generated was comparable with or much higher than that of cGMP, whose production profile slightly preceded 8-nitro-cGMP formation in the activated inducible NO synthase-expressing cells. These unexpectedly large amounts of 8-nitro-cGMP suggest that GTP (a substrate of cGMP biosynthesis), rather than cGMP per se, may undergo guanine nitration. Also, 8-nitro-cGMP caused S-guanylation of KEAP1 in cells, which led to Nrf2 activation and subsequent induction of antioxidant enzymes, including heme oxygenase-1; thus, 8-nitro-cGMP protected cells against cytotoxic effects of hydrogen peroxide. Proteomic analysis for endogenously modified KEAP1 with matrix-assisted laser desorption/ionization time-of-flight-tandem mass spectrometry revealed that 8-nitro-cGMP S-guanylated the Cys434 of KEAP1. The present report is therefore the first substantial corroboration of the biological significance of cellular 8-nitro-cGMP formation and potential roles of 8-nitro-cGMP in the Nrf2-dependent antioxidant response. 相似文献
996.
Toyo-oka K Mori D Yano Y Shiota M Iwao H Goto H Inagaki M Hiraiwa N Muramatsu M Wynshaw-Boris A Yoshiki A Hirotsune S 《The Journal of cell biology》2008,180(6):1133-1147
Protein phosphatase 4 catalytic subunit (PP4c) is a PP2A-related protein serine/threonine phosphatase with important functions in a variety of cellular processes, including microtubule (MT) growth/organization, apoptosis, and tumor necrosis factor signaling. In this study, we report that NDEL1 is a substrate of PP4c, and PP4c selectively dephosphorylates NDEL1 at Cdk1 sites. We also demonstrate that PP4c negatively regulates Cdk1 activity at the centrosome. Targeted disruption of PP4c reveals disorganization of MTs and disorganized MT array. Loss of PP4c leads to an unscheduled activation of Cdk1 in interphase, which results in the abnormal phosphorylation of NDEL1. In addition, abnormal NDEL1 phosphorylation facilitates excessive recruitment of katanin p60 to the centrosome, suggesting that MT defects may be attributed to katanin p60 in excess. Inhibition of Cdk1, NDEL1, or katanin p60 rescues the defective MT organization caused by PP4 inhibition. Our work uncovers a unique regulatory mechanism of MT organization by PP4c through its targets Cdk1 and NDEL1 via regulation of katanin p60 distribution. 相似文献
997.
Hayward LJ Rodriguez JA Kim JW Tiwari A Goto JJ Cabelli DE Valentine JS Brown RH 《The Journal of biological chemistry》2002,277(18):15923-15931
Over 90 different mutations in the gene encoding copper/zinc superoxide dismutase (SOD1) cause approximately 2% of amyotrophic lateral sclerosis (ALS) cases by an unknown mechanism. We engineered 14 different human ALS-related SOD1 mutants and obtained high yields of biologically metallated proteins from an Sf21 insect cell expression system. Both the wild type and mutant "as isolated" SOD1 variants were deficient in copper and were heterogeneous by native gel electrophoresis. By contrast, although three mutant SOD1s with substitutions near the metal binding sites (H46R, G85R, and D124V) were severely deficient in both copper and zinc ions, zinc deficiency was not a consistent feature shared by the as isolated mutants. Eight mutants (A4V, L38V, G41S, G72S, D76Y, D90A, G93A, and E133 Delta) exhibited normal SOD activity over pH 5.5-10.5, per equivalent of copper, consistent with the presumption that bound copper was in the proper metal-binding site and was fully active. The H48Q variant contained a high copper content yet was 100-fold less active than the wild type enzyme and exhibited a blue shift in the visible absorbance peak of bound Cu(II), indicating rearrangement of the Cu(II) coordination geometry. Further characterization of these as-isolated SOD1 proteins may provide new insights regarding mutant SOD1 enzyme toxicity in ALS. 相似文献
998.
Mamura M Nakao A Goto D Kato M Saito Y Iwamoto I 《Biochemical and biophysical research communications》2000,268(1):124-127
TGF-beta modulates immune responses by regulating T cell function. The Smad family of proteins has been recently shown to transduce signals for the TGF-beta superfamily and Smad2 mediates TGF-beta signaling. Here, we showed that TGF-beta phosphorylated Smad2 and induced interaction between Smad2 and Smad4 in primary T cells and the Jurkat T cell line. Interestingly, ligation of the T cell receptor (TCR)/CD3 complex with anti-CD3 mAb also phosphorylated Smad2, but failed to induce interaction between Smad2 and Smad4 in the Jurkat T cell line. Phosphorylation of Smad2 via the TCR/CD3 complex was not abrogated by treatment with neutralizing antibody against TGF-beta. Furthermore, PD98059, a MEK inhibitor, suppressed Smad2 phosphorylation by stimulation with anti-CD3 mAb in Jurkat T cell line. These findings indicated that not only TGF-beta but also stimulation via the TCR/CD3 complex phosphorylated Smad2 through mitogen-activated protein (MAP) kinase cascades, suggesting that Smad2 may function in both TGF-beta- and TCR/CD3 complex-mediated signaling pathways in T cells. 相似文献
999.
Sato Y Hatta M Karim MF Sawa T Wei FY Sato S Magnuson MA Gonzalez FJ Tomizawa K Akaike T Yoshizawa T Yamagata K 《The Journal of biological chemistry》2012,287(27):23236-23245
1000.
Matsuda S Niidome T Nonaka H Goto Y Fujimura K Kato M Nakanishi M Akaike A Kihara T Sugimoto H 《Biochemical and biophysical research communications》2008,368(4):971-976
Microglia are believed to play an important role in the regulation of phagocytosis, neuronal survival, neuronal cell death, and inflammation. Recent studies have demonstrated that microglia are multipotential stem cells that give rise to neurons, astrocytes, and oligodendrocytes. However, the functional properties of neurons derived from microglia are poorly understood. In this study, we investigated the possibility that microglia differentiate into functional neurons. Immunocytochemical study demonstrated that microtubule-associated protein 2 (MAP2)-positive cells were derived from microglia under differentiation conditions. Intracellular Ca2+ imaging study demonstrated that KCl caused no significant changes in [Ca2+]i in microglia, whereas it caused a remarkable increase in [Ca2+]i in microglia-derived cells. Furthermore, electrophysiological study demonstrated that the spike waveform, firing rate, and tetrodotoxin sensitivity of extracellular action potentials evoked by 4-aminopyridine from microglia-derived MAP2-positive cells were nearly identical to those from cultured cortical neurons. These results suggest that microglia-derived MAP2-positive cells possess properties of functional neurons. 相似文献