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991.
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994.
Kobae Y Mizutani M Segami S Maeshima M 《Bioscience, biotechnology, and biochemistry》2006,70(4):980-987
Aquaporins mediate the movement of water across biomembranes. Arabidopsis thaliana contains 35 aquaporins that belong to four subfamilies (PIP, TIP, SIP, and NIP). We investigated their expression profiles immunochemically in suspension-cultured Arabidopsis thaliana cells during growth and in response to salt and osmotic stresses. Protein amounts of all aquaporins were much lower in cultured cells than in the plant tissues. This is consistent with the low water permeability of protoplasts from cultured cells. After treatment with NaCl, the protein amounts of PIP2;1, PIP2;2, and PIP2;3 in the cells increased several-fold, and those of TIP1;1 and TIP1;2, 15- and 3-fold respectively. PIP1 did not change under the stress. Cell death began after 19 d in culture, accompanied by marked accumulation of PIPs and TIPs and a gradual decrease in SIPs. Our results suggest the followings: (i) Accumulation of aquaporin isoforms was individually regulated at low levels in single cells. (ii) At least PIP2;2, PIP2;3, TIP1;1, and TIP1;2 are stress-responsive aquaporins in suspension cells. (iii) A sudden increment of several members of PIP2 and TIP1 subfamilies might be related to cell death. 相似文献
995.
We previously reported a quantitative trait locus for body weight, non-insulin-dependent diabetes 5 (Nidd5), on Chromosome 2 in the TSOD (Tsumura, Suzuki, Obese Diabetes) mouse, a model of polygenic obese type 2 diabetes. To find
the gene responsible for a specific component of the pathogenesis, we used a marker-assisted selection protocol to produce
congenic strains. These mice are designed to carry a control BALB/cA-derived genomic interval and a TSOD background to look
for loss of phenotype. One of the strains with the widest congenic interval, D2Mit297-D2Mit304, showed reductions in both body weight and adiposity compared with TSOD mice. The phenotypic analyses of other congenic strains
further narrowed the locus in a 9.4-Mb interval between D2Mit433 and D2Mit91, around which numerous loci for body weight and adiposity have been mapped previously. Although the locus showed a relatively
modest effect on body weight, it had a major influence on fat mass that explains approximately 60% of the difference in the
adipose index between parental TSOD and BALB/cA mice. Furthermore, the congenic strain with a minimal BALB/cA-derived region
showed significantly smaller cell sizes of white and brown adipocytes compared with the control littermates. However, the
locus did not primarily affect food consumption, general activity, or rectal temperature after cold exposure, although there
are clear differences in these traits between the parental strains. The present work physically delineates the major locus
for adiposity in the TSOD mouse. 相似文献
996.
Inorganic polyphosphate is a biological macromolecule consisting of multiple phosphates linked by high-energy bonds. Polyphosphate occurs in cells from all domains of life, and is known to play roles in a diverse collection of cellular functions. Here we examine the relationship between polyphosphate and protein synthesis in Escherichia coli. We report that polyphosphate associates with E. coli ribosomes in vitro. Characterization of this interaction reveals that both long-chain and short-chain polyphosphates interact with the ribosome. Intact 70S ribosomes, as well as 50S and 30S subunits, display a specific interaction with polyphosphate that is mediated primarily by contacts with ribosomal proteins. Additionally, we examined functional consequences of a ppk mutation, which severely reduces levels of intracellular polyphosphate. Extracts from ppk mutants contain lower levels of polysomes than wild-type cells, suggesting a defect in mRNA utilization or the mRNA-ribosome interaction. Ribosomes from wild-type and ppk mutant cells were isolated, and their activities were compared using a polyU RNA in vitro translation assay. While rates of polyphenylalanine synthesis are similar, use of ribosomes from ppk cells results in a misincorporation rate about five times higher compared with the rate observed when ribosomes from wild-type cells are used. Mistranslation rates in vivo were measured directly, and ppk mutants displayed higher readthrough frequencies for two different stop codons. Taken together, these results indicate that polyphosphate plays an important role in maintaining optimal translation efficiency in vivo and in vitro. 相似文献
997.
The LolCDE complex of Escherichia coli belongs to the ABC transporter superfamily and initiates the lipoprotein sorting to the outer membrane by catalysing their release from the inner membrane. LolC and/or LolE, membrane subunits, recognize lipoproteins anchored to the outer surface of the inner membrane, while LolD hydrolyses ATP on its inner surface. We report here that ligand-bound LolCDE can be purified from the inner membrane in the absence of ATP. Liganded LolCDE represents an intermediate of the release reaction and exhibits higher affinity for ATP than the unliganded form. ATP binding to LolD weakens the interaction between LolCDE and lipoproteins and causes their dissociation in a detergent solution, while lipoprotein release from membranes requires ATP hydrolysis. Liganded LolCDE thus reveals molecular events brought about through ATP binding and hydrolysis. LolCDE is the first example of an ABC transporter purified with tightly bound native substrates. A single molecule of lipoprotein is found to bind per molecule of the LolCDE complex. 相似文献
998.
Satoshi Kishigami Hiroshi Ohta Eiji Mizutani Sayaka Wakayama Hong-Thuy Bui Nguyen Van Thuan Takafusa Hikichi Rinako Suetsugu Teruhiko Wakayama 《Central European Journal of Biology》2006,1(3):376-385
Trichostatin A (TSA), a histone deacetylase inhibitor, is a known teratogen causing malformations such as vertebral fusions
when applied during the postimplantation period; TSA also causes developmental arrest when applied during the preimplantation
period. Regardless of these hindrances, we have succeeded in the establishment of an efficient somatic cloning method for
the mouse where reconstructed embryos are treated with TSA. To elucidate this apparent discrepancy, we treated fertilized
mouse embryos generated either by intracytoplasmic sperm injection (ICSI) or round spermatid injection (ROSI) with 50 nM TSA
for 20 h after fertilization as well as parthenogenetic embryos and found that TSA treatment inhibited the preimplantation
development of ICSI embryos but not ROSI or parthenogenetic embryos. And, although we often observed hypomorphism following
TSA treatment in embryos grown to full term produced by both ICSI (av. of body weight: 1.7 g vs. 1.5 g) and ROSI (1.6 g vs.
1.2 g), TSA treatment reduced the offspring production rate for ICSI from 57% to 34% but not for ROSI from 30% to 36%. Thus,
these data indicate that the effects, harmful or not, of TSA treatment on embryonic development depend on their nuclear derivations.
Also, the resulting hypomorphism after TSA treatment is a caveat for this procedure in current Assisted Reproductive Technologies. 相似文献
999.
Yuko Mitobe Sayaka Ito Takashi Mizutani Tsuyoshi Nagase Nagaaki Sato Shigeru Tokita 《Bioorganic & medicinal chemistry letters》2009,19(15):4075-4078
Radioligands are powerful tools for examining the pharmacological profiles of chemical leads and thus facilitate drug discovery. In this study, we identified and characterized 3-([1,1,1-3H]methyl)-2-(4-{[3-(1-pyrrolidinyl)propyl]oxy} phenyl)-4(3H)-quinazolinone ([3H]1) as a potent and selective radioligand for histamine H3 receptors. Radioligand [3H]1 exhibited appreciable specific signal in brain slices prepared from wild-type mice but not from histamine H3 receptor-deficient mice, demonstrating the specificity and utility of [3H]1 as a selective histamine H3 receptor radioligand for ex-vivo receptor occupancy assays. 相似文献
1000.
Yasushi Todoroki Hikaru Aoyama Saori Hiramatsu Minaho Shirakura Hataitip Nimitkeatkai Satoru Kondo Kotomi Ueno Masaharu Mizutani Nobuhiro Hirai 《Bioorganic & medicinal chemistry letters》2009,19(19):5782-5786
We enlarged the uniconazole (UNI) molecule to find a specific inhibitor of abscisic acid (ABA) 8′-hydroxylase, and synthesized various UNI derivatives that were substituted with hydrophilic and hydrophobic groups at the 4-chlorine of the phenyl group of UNI using click chemistry. Considering its potency in ABA 8′-hydroxylase inhibition, its small effect on seedling growth, and its ease of application, UT4, the UNI derivative containing the C4 alkyltriazole, was the best candidate for a highly selective inhibitor of ABA 8′-hydroxylase. 相似文献