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51.
Neutral red (NR) in the culture medium entered the vacuolesof a green alga, Micrasterias pinnatifida, at a higher rateat pH 8 than at pH 5. NR remained soluble in vacuoles of cellscultured at pH 5, while it precipitated and formed granulesin cells cultured at pH 8. The vacuoles of cells cultured atpH 8 contained fibrils, but those of cells cultured at pH 5did not. The amount of NR that entered the cells was markedlyreduced by the addition to the medium of nigericin at 10-5M,monensin at 10-5M, bafilo-mycin A1 at 10-5M, or ammonium chlorideat 50 mM. The formation of NR granules in vacuoles were stronglyinhibited and the disorganization of NR granules were acceleratedby the addition of nigericin at 10-5M, or bafilomycin A1 at10-5M to the culture medium. The possibility is discussed thatNR which enters vacuoles might become positively charged (NRH+)by protons brought into vacuoles by proton pumps and that NRH+might combine with some negatively charged macromolecules toform aggregates or granules. (Received April 18, 1996; Accepted May 27, 1996) 相似文献
52.
Sub Sunoo Katsumi Asano Fumiyuki Mitsumori 《European journal of applied physiology and occupational physiology》1996,74(4):305-310
We measured ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and the intracellular pH in rat hindlimb muscles during submaximal isometric exercise with various O2 deliveries using31P nuclear magnetic resonance spectroscopy (31P NMR) to evaluate changes in energy metabolism in relation to O2 availability. Delivery of O2 to muscles was altered by controlling the fractional concentration of inspired oxygen (F
IO2) at 0.50, 0.28, 0.21, 0.11 and 0.08 with monitoring partial pressure of oxygen and carbon dioxide, and bicarbonate at the femoral artery. The steady-state ratio of PCr : (PCr + Pi) during exercise decreased as a function ofF
IO2 even at 0.21. Significant acidification of the intracellular pH during exercise occurred at 0.08F
IO2. Change in the PCr : (PCr + Pi) ratio demonstrated that the oxidative capacity, i.e. the maximal rate of the oxidative phosphorylation reaction, in muscle was not limited by O2 delivery at 0.50F
IO2, but was significantly limited at 0.21F
IO2 or below. Change in the intracellular pH at 0.08F
IO2 could be interpreted as an increase in lactate, suggesting activation of glycolysis. Correlation between the PCr : (PCr + Pi) ratio and the intracellular pH revealed the existence of a critical PCr : (PCr + Pi) ratio and pH for glycolysis activation at around 0.4 and 6.7, respectively. 相似文献
53.
54.
Katsumi Mominoki Noriko Nakagawa-Tosa Masami Morimatsu Bunei Syuto Masayuki Saito 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1995,110(4):785-789
Haptoglobin (Hp), a hemoglobin-binding protein in plasma, consists of α and β subunits and has a tetra-chain arrangement (β-α-α-β) connected by disulfide bridges in most mammals so far examined. Dog Hp has been reported to be unique compared with other Hps in respect that (1) the two αβ units are joined by a non-covalent interaction rather than a disulfide bridge and (2) the α chain has an oligosaccharide-binding sequence (Asn-X-Ser/Thr) and is glycosylated. To determine whether the unique structures of dog Hp are common in the Carnivora, we purified Hps from sera of bear and cat, and analyzed their subunit structure and partial amino acid sequences. The analyses by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under both reducing and non-reducing conditions, revealed that bear and cat Hps have similar subunit arrangements to dog Hp, suggesting the absence of a disulfide bridge between two α chains. This was confirmed by amino acid sequence analysis of the α chains: that is, Cys15 participating in the inter-α chain disulfide bridge was replaced by Val in bear or Leu in cat and dog. Thus, the unique subunit arrangement of Hp reported in dog may be common in the Carnivora. In contrast to dog Hp, however, α chains of bear and cat Hps were found not to have the typical oligosaccharide binding sequence on their α chains and were not glycosylated. 相似文献
55.
56.
Inactivation of bleomycin by an N-acetyltransferase in the bleomycin-producing strain Streptomyces verticillus 总被引:1,自引:0,他引:1
Masanori Sugiyama Takanori Kumagai Mitsuhiko Shionoya Eiichi Kimura Julian E. Davies 《FEMS microbiology letters》1994,121(1):81-85
Abstract Bleomycin-producing Streptomyces verticillus ATCC15003 possesses a bleomycin acetyltransferase which inactivates the drug in the presence of acetyl coenzyme A. The site of acylation in enzymically prepared acetylbleomycin A2 was determined by nuclear magnetic resonance analysis; the primary amino group of the β-aminoalanine moiety of bleomycin was acetylated. Acetylbleomycin A2 had no detectable antibacterial activity and did not induce in vitro DNA degradation. 相似文献
57.
Role of cellular antioxidants in metal-induced damage 总被引:23,自引:0,他引:23
M. Sugiyama 《Cell biology and toxicology》1994,10(1):1-22
58.
For phylogenetic analysis of the higher fungi, we sequenced the nuclear small subunit rRNA (18S rRNA) gene fromTaphrina populina, the type species of the genusTaphrina, andProtomyces lactucae-debilis. The molecular phylogeny inferred from these 2 sequences and 75 sequences from the DNA data bank divided the Ascomycota into three major lineages: the hemiascomycetes, the euascomycetes, and the archiascomycetes, newly described herein. The former two lineages are monophyletic, whereas the archiascomycetes, which originated first and are comprised ofTaphrina, Protomyces, Saitoella, Schizosaccharomyces, andPneumocystis, may not be monophyletic. Among the archiascomycetes, theTaphrina/Protomyces branch is monophyletic. Confirmation of the archiascomycetes as a monophyletic taxonomic class will require comparison of additional genetically defined characters.This work was supported in part by grants 05454030 from the Ministry of Education, Science, and Culture of Japan (to J. S.) and 4369 from the Japan Society for the Promotion of Science Fellowship Programs (to H. N.). 相似文献
59.
60.
Yasushi Sato Munetaka Sugiyama Ryszard J. Górecki Hiroo Fukuda Atsushi Komamine 《Planta》1993,189(4):584-589
In a culture system in which single cells isolated from the mesophyll of Zinnia elegans L. differentiate to tracheary elements (TEs), two inhibitors of phenylalanine ammonia-lyase (EC 4.3.1.5), L-α-aminooxy-β-phenylpropionic acid (AOPP) at 10 μM inhibited lignification without reducing the number of TEs formed. These inhibitors caused intracellular changes in peroxidase (EC 1.11.1.7) activities. The inhibitors increased the activity of peroxidases bound to the cell walls and especially the activity of peroxidase bound ionically to the cell walls. In contrast, the activity of extracellular peroxidase decreased. There were five isoenzymes, P1-P5, in the ionically bound peroxidase of cultured Zinnia cells. Among the isoenzymes, P4 and P5 appeared to be specific for TE differentation. Treatment with AOPP and AIP resulted in increases in the activities of P2, P4 and P5 isoenzymes, with the most prominent increase in P5 activity. The addition of lignin precursors, including coniferyl alcohol, to the AOPP-treated cells restored lignification, and suppressed the alteration of peroxidase isoenzyme patterns caused by AOPP. The relationship between the wall-bound peroxidases and lignification during TE differentiation is discussed in the light of these results. 相似文献