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51.
Sugiura T Yoshinaga N Kondo S Waku K Ishima Y 《Biochemical and biophysical research communications》2000,271(3):654-658
The levels of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand, and other molecular species of monoacylglycerols in rat brain were examined. In this study, we sacrificed the animals in liquid nitrogen to minimize postmortem changes. We found that rat brain contains 0.23 nmol/g tissue of 2-arachidonoylglycerol, which accounts for 10.5% of the total monoacylglycerol present in this tissue. We next investigated the level of 2-arachidonoylglycerol after in vivo stimulation with picrotoxinin. We found that the level of 2-arachidonoylglycerol was elevated markedly in picrotoxinin-administered rat brain (4- to 6-fold over the control level). Changes in the levels of other molecular species were relatively small or negligible. Several cannabimimetic molecules as well as Delta(9)-tetrahydrocannabinol are known to depress neurotransmission and to exert anticonvulsant activities; endogenous 2-arachidonoylglycerol produced during neural excitation may play a regulatory role in calming the enhanced synaptic transmission. 相似文献
52.
Matsumoto N Yoshinaga H Ohmura N Ando A Saiki H 《Biotechnology and bioengineering》2000,70(4):464-466
Electrolytic cultivation was applied to Leptospirillum ferrooxidans strains P3A and CF27, which use ferrous iron to respire aerobically. Ferrous iron was supplied to the bacteria by intermittent electrolytic reduction of ferric iron as electron shuttle using an electrode. The yield of L. ferrooxidans and strain CF27 reached 20- and 50-fold, respectively, higher density than were achievable yields without electrolysis. The time required to obtain high density depended not on the growth ratio, but rather on the original growth rate of each strain. 相似文献
53.
In this study we examined the behaviour and role of an intra-acrosomal antigenic molecule, acrin 3, during mouse fertilisation in vitro by assessing the effect of its pertinent monoclonal antibody mMC101. Experiments were designed to assess the effect of mMC101 on sperm-zona pellucida binding, the acrosome reaction, zona pellucida penetration, sperm-egg fusion, and fertilisation in vitro. mMC101 did not affect sperm motility or primary and secondary binding to the zona pellucida, but significantly inhibited fertilisation of zona-pellucida-intact oocytes in a dose-dependent manner. In the presence of mMC101 at 100 microg/ml concentration in TYH medium, none of the oocytes developed to pronuclear stage by 5 h after co-incubation of the gametes, but the pronucleus formation rate recovered to some extent (45.3%) after 8 h, indicating a delay of early embryonic development. mMC101 also delayed and significantly suppressed zona pellucida penetration by sperm. Acrin 3 dispersed and did not remain on completely acrosome-reacted sperm. Although mMC101 did not influence the zona-pellucida-induced acrosome reaction, it significantly inhibited fertilisation when acrosome-reacted sperm in the presence of mMC101 inseminated zona-pellucida-free oocytes. However, fertilisation remained unaffected when acrosome-reacted sperm in the absence of mMC101 inseminated zona-pellucida-free oocytes even in its presence. Thus, acrin 3 appears to facilitate zona pellucida penetration and is also likely to be involved in sperm-oocyte fusion by modifying the sperm plasma membrane during the acrosome reaction. 相似文献
54.
Ryosuke Tateishi Nobuko Akiyama Maki Miyauchi Riko Yoshinaga Hiroki Sasanuma Takashi Kudo Miki Shimbo Masahiro Shinohara Koji Obata Jun-ichiro Inoue Masaki Shirakawa Dai Shiba Hiroshi Asahara Nobuaki Yoshida Satoru Takahashi Hironobu Morita Taishin Akiyama 《PloS one》2015,10(10)
Gravity change affects many immunological systems. We investigated the effects of hypergravity (2G) on murine thymic cells. Exposure of mice to 2G for three days reduced the frequency of CD4+CD8+ thymocytes (DP) and mature medullary thymic epithelial cells (mTECs), accompanied by an increment of keratin-5 and keratin-8 double-positive (K5+K8+) TECs that reportedly contain TEC progenitors. Whereas the reduction of DP was recovered by a 14-day exposure to 2G, the reduction of mature mTECs and the increment of K5+K8+ TEC persisted. Interestingly, a surgical lesion of the inner ear’s vestibular apparatus inhibited these hypergravity effects. Quantitative PCR analysis revealed that the gene expression of Aire and RANK that are critical for mTEC function and development were up-regulated by the 3-day exposure and subsequently down-regulated by the 14-day exposure to 2G. Unexpectedly, this dynamic change in mTEC gene expression was independent of the vestibular apparatus. Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system. These data might provide insight on the impact of gravity change on thymic functions during spaceflight and living. 相似文献
55.
The current mechanistic model of chaperonin-assisted protein folding assumes that the substrate protein in the cage, formed by GroEL central cavity capped with GroES, is isolated from outside and exists as a free polypeptide. However, using ATPase-deficient GroEL mutants that keep GroES bound, we found that, in the rate-limiting intermediate of a chaperonin reaction, the unfolded polypeptide in the cage partly protrudes through a narrow space near the GroEL/GroES interface. Then, the entire polypeptide is released either into the cage or to the outside medium. The former adopts a native structure very rapidly and the latter undergoes spontaneous folding. Partition of the in-cage folding and the escape varies among substrate proteins and is affected by hydrophobic interaction between the polypeptide and GroEL cavity wall. The ATPase-active GroEL with decreased in-cage folding produced less of a native model substrate protein in Escherichia coli cells. Thus, the polypeptide in the critical GroEL-GroES complex is neither free nor completely confined in the cage, but it is interacting with GroEL's apical region, partly protruding to outside. 相似文献
56.
Ismiarni Komala Takuya Ito Fumihiro Nagashima Yasuyuki Yagi Masatoshi Kawahata Kentaro Yamaguchi Yoshinori Asakawa 《Phytochemistry》2010,71(11-12):1387-1394
Cembrane-type diterpenoids, 13,18,20-epi-iso-chandonanthone (1) and (8E)-4α-acetoxy-12α,13α-epoxycembra-1(15),8-diene (2), two fusicoccane-type diterpenoids, fusicoauritone 6α-methyl ether (3) and 6β,10β-epoxy-5β-hydroxyfusicocc-2-ene (4) and a zierane sesquiterpene γ-lactone, chandolide (5) were isolated from the Tahitian liverwort Chandonanthus hirtellus (Web.) Mitt., together with eight known diterpenoids, chandonanthine (6), fusicogigantone A (7), fusicogigantone B (8), fusicogigantepoxide (9), anadensin (10), fusicoauritone (11), ent-verticillol (12) and ent-epi-verticillol (13). Their structures were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analyses. Compounds 1, 5 and 10 showed weak cytotoxic activity against HL-60. Compound 3 also indicated weak cytotoxic activity against KB cell lines. 相似文献
57.
We investigated the spatial and temporal distribution of xylans in the cell walls of differentiating earlywood tracheids of
Cryptomeria japonica using two different types of monoclonal antibodies (LM10 and LM11) combined with immunomicroscopy. Xylans were first deposited
in the corner of the S1 layer in the early stages of S1 formation in tracheids. Cell corner middle lamella also showed strong xylan labeling from the early stage of cell wall formation.
During secondary cell wall formation, the innermost layer and the boundary between the S1 and S2 layers (S1/S2 region) showed weaker labeling than other parts of the cell wall. However, mature tracheids had an almost uniform distribution
of xylans throughout the entire cell wall. Xylan localization labeled with LM10 antibody was stronger in the outer S2 layer than in the inner layer, whereas xylans labeled with LM11 antibody were almost uniformly distributed in the S2 layer. In addition, the LM10 antibody showed almost no xylan labeling in the S1/S2 region, whereas the LM11 antibody revealed strong xylan labeling in the S1/S2 region. These findings suggest that structurally different types of xylans may be deposited in the tracheid cell wall depending
on the developmental stage of, or location in, the cell wall. Our study also indicates that deposition of xylans in the early
stages of tracheid cell wall formation may be spatially consistent with the early stage of lignin deposition in the tracheid
cell wall. 相似文献
58.
Yoshinaga T Akiyama K Nishida S Nakane M Ogawa K Hirose H 《Diseases of aquatic organisms》2007,78(2):155-160
A medium for the in vitro culture of Cryptocaryon irritans, which is an obligatorily parasitic ciliate of marine teleosts and causes 'white spot disease', was developed. The medium consisted of a layer of cultured fish cells (FHM), with an agarose gel layer covering the cell layer. The agarose gel contained 0.22% agarose, 10% fetal calf serum, 100 I.U. ml(-1) Penicillin G potassium and 100 microg ml(-1) streptomycin sulphate. Theronts of C. irritans transformed to trophonts and grew to 180 microm in mean length in the medium, although they gradually decreased in number. When trophonts fully developed in medium were transferred into seawater 4 d after inoculation, approximately 70% of them transformed to encysted tomonts and released theronts. When fish were challenged with theronts obtained from in vitro-raised parasites, approximately 40% of the theronts were recovered from fish, indicating comparative infectivity of in vitro-raised theronts to those of in vivo-raised theronts. This is the first report that C. irritans fully developed in vitro and its entire life cycle was completed without a host fish. 相似文献
59.
Sakane I Hongo K Motojima F Murayama S Mizobata T Kawata Y 《Journal of molecular biology》2007,367(4):1171-1185
In order to understand how inter-subunit association stabilizes oligomeric proteins, a single polypeptide chain variant of heptameric co-chaperonin GroES (tandem GroES) was constructed from Escherichia coli heptameric GroES by linking consecutively the C-terminal of one subunit to the N-terminal of the adjacent subunit with a small linker peptide. The tandem GroES (ESC7) showed properties similar to wild-type GroES in structural aspects and co-chaperonin activity. In unfolding and refolding equilibrium experiments using guanidine hydrochloride (Gdn-HCl) as a denaturant at a low protein concentration (50 microg ml(-1)), ESC7 showed a two-state transition with a greater resistance toward Gdn-HCl denaturation (Cm=1.95 M) compared to wild-type GroES (Cm=1.1 M). ESC7 was found to be about 10 kcal mol(-1) more stable than the wild-type GroES heptamer at 50 microg ml(-1). Kinetic unfolding and refolding experiments of ESC7 revealed that the increased stability was mainly attributed to a slower unfolding rate. Also a transient intermediate was detected in the refolding reaction. Interestingly, at the physiological GroES concentration (>1 mg ml(-1)), the free energy of unfolding for GroES heptamer exceeded that for ESC7. These results showed that at low protein concentrations (<1 mg ml(-1)), the covalent linking of subunits contributes to the stability but also complicates the refolding kinetics. At physiological concentrations of GroES, however, the oligomeric state is energetically preferred and the advantages of covalent linkage are lost. This finding highlights a possible advantage in transitioning from multi-domain proteins to oligomeric proteins with small subunits in order to improve structural and kinetic stabilities. 相似文献
60.
Amino acid substitutions in the s2 region enhance severe acute respiratory syndrome coronavirus infectivity in rat angiotensin-converting enzyme 2-expressing cells
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Fukushi S Mizutani T Sakai K Saijo M Taguchi F Yokoyama M Kurane I Morikawa S 《Journal of virology》2007,81(19):10831-10834
To clarify the molecular basis of severe acute respiratory syndrome coronavirus (SARS-CoV) adaptation to different host species, we serially passaged SARS-CoV in rat angiotensin-converting enzyme 2 (ACE2)-expressing cells. After 15 passages, the virus (Rat-P15) came to replicate effectively in rat ACE2-expressing cells. Two amino acid substitutions in the S2 region were found on the Rat-P15 S gene. Analyses of the infectivity of the pseudotype-bearing S protein indicated that the two substitutions in the S2 region, especially the S950F substitution, were responsible for efficient infection. Therefore, virus adaptation to different host species can be induced by amino acid substitutions in the S2 region. 相似文献