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151.
Nobuko Motomura Keiko Shimizu Makoto Shimizu Shinobu Aoki-Komori Kazumi Taniguchi Isao Serizawa Toru R Saito 《Experimental Animals》2002,51(2):187-190
The purpose of this study was to determine whether species differences in neonatal vocalizations of rodent pups could be observed. Ultrasonic vocalizations of pups of 5 rodent species, mouse (ICR), vole (Microtus arvalis), Syrian hamster, rat (Wistar-Imamichi), and Mongolian gerbil were recorded from 3 to 15 or 21 days of age. Recordings were made under conditions of separation from mothers and litter mates in a cooled chamber (approximately 10 degrees C). The major species differences observed were age specific and species specific frequencies. The Mongolian gerbil displayed a different frequency change with age. Namely, the day on which ultrasonic vocalizations ceased was delayed in Mongolian gerbil compared with the other rodents. The modal peak frequencies of ultrasound emitted from pups at 3 days of age were low (around 35 kHz) in the vole and the Syrian hamster, medium (around 45 kHz) in the rat and the Mongolian gerbil, and high (around 55 kHz) in the mouse. 相似文献
152.
Atsuhiro Shimada Fumiyoshi Hara Kyoko Shinzawa-Itoh Nobuko Kanehisa Eiki Yamashita Kazumasa Muramoto Tomitake Tsukihara Shinya Yoshikawa 《The Journal of biological chemistry》2021,297(3)
Mammalian cytochrome c oxidase (CcO) reduces O2 to water in a bimetallic site including Fea3 and CuB giving intermediate molecules, termed A-, P-, F-, O-, E-, and R-forms. From the P-form on, each reaction step is driven by single-electron donations from cytochrome c coupled with the pumping of a single proton through the H-pathway, a proton-conducting pathway composed of a hydrogen-bond network and a water channel. The proton-gradient formed is utilized for ATP production by F-ATPase. For elucidation of the proton pumping mechanism, crystal structural determination of these intermediate forms is necessary. Here we report X-ray crystallographic analysis at ∼1.8 Å resolution of fully reduced CcO crystals treated with O2 for three different time periods. Our disentanglement of intermediate forms from crystals that were composed of multiple forms determined that these three crystallographic data sets contained ∼45% of the O-form structure, ∼45% of the E-form structure, and ∼20% of an oxymyoglobin-type structure consistent with the A-form, respectively. The O- and E-forms exhibit an unusually long CuB2+-OH− distance and CuB1+-H2O structure keeping Fea33+-OH− state, respectively, suggesting that the O- and E-forms have high electron affinities that cause the O→E and E→R transitions to be essentially irreversible and thus enable tightly coupled proton pumping. The water channel of the H-pathway is closed in the O- and E-forms and partially open in the R-form. These structures, together with those of the recently reported P- and F-forms, indicate that closure of the H-pathway water channel avoids back-leaking of protons for facilitating the effective proton pumping. 相似文献
153.
Masahiko Ishida Ryoichi Haga Nobuko Nishimura Harumi Matuzaki Ryusei Nakano 《Cytotechnology》1990,4(3):215-225
Gas sparging directly into the culture-broth is not done in cell culture, except when the gas flow rate is very small, because much foaming occurs.During screening of defoaming methods, foam was observed to be broken up effectively when it made contact with a net fabricated from hydrophobic materials. Providing a highly efficient oxygen supply to suspension culture was tried using the new defoaming method. In a 5 1 reactor equipped with the foam-eliminating net fabricated with polysiloxane, oxygen was transferred at 21 mmole/l·h equivalent to an about forty-fold higher rate than in conventional surface aeration. This was equivalent to a consumption rate of 1×108 cells/ml, even at a low oxygen gas flow rate of 0.1 cm/s corresponding to a fourth of the gas flow rate when foam leaked through the net.Perfusion culture of rat ascites hepatoma cell JTC-1 was successfully carried out in the 51 scale culture system with the net and a hydrophobic membrane for cell filtration. The viable cell concentration reached 2.7×107 cells/ml after twenty-seven days, in spite of the nutrient-deficient condition of the lower medium exchange rate, that is, a working volume a day, and viability was maintained at more than 90%. In a 1.21 scale culture of mouse-mouse hybridoma cell STK-1, viable cell concentration reached 4×107 cells/ml. These results showed that oxygen transfer by gas sparging with defoaming was useful for high density suspension culture. A foam-breaking mechanism was proposed.Abbreviations Eagle's MEM
Eagle's minimal essential medium
- Dulbecco's modified Eagle MEM
Dulbecco's modified Eagle minimal essential medium 相似文献
154.
Inoue T Irikura D Okazaki N Kinugasa S Matsumura H Uodome N Yamamoto M Kumasaka T Miyano M Kai Y Urade Y 《Nature structural biology》2003,10(4):291-296
Here we report the crystal structures of human hematopoietic prostaglandin (PG) D synthase bound to glutathione (GSH) and Ca2+ or Mg2+. Using GSH as a cofactor, prostaglandin D synthase catalyzes the isomerization of PGH2 to PGD2, a mediator for allergy response. The enzyme is a homodimer, and Ca2+ or Mg2+ increases its activity to approximately 150% of the basal level, with half maximum effective concentrations of 400 microM for Ca2+ and 50 microM for Mg2+. In the Mg2+-bound form, the ion is octahedrally coordinated by six water molecules at the dimer interface. The water molecules are surrounded by pairs of Asp93, Asp96 and Asp97 from each subunit. Ca(2+) is coordinated by five water molecules and an Asp96 from one subunit. The Asp96 residue in the Ca2+-bound form makes hydrogen bonds with two guanidium nitrogen atoms of Arg14 in the GSH-binding pocket. Mg2+ alters the coordinating water structure and reduces one hydrogen bond between Asp96 and Arg14, thereby changing the interaction between Arg14 and GSH. This effect explains a four-fold reduction in the K(m) of the enzyme for GSH. The structure provides insights into how Ca2+ or Mg2+ binding activates human hematopoietic PGD synthase. 相似文献
155.
Hiromi Sawai Hiroto Otani Nobuko Arisue Nirianne Palacpac Leonardo de Oliveira Martins Sisira Pathirana Shiroma Handunnetti Satoru Kawai Hirohisa Kishino Toshihiro Horii Kazuyuki Tanabe 《BMC evolutionary biology》2010,10(1):1-12
Background
The 200 kDa merozoite surface protein 1 (MSP-1) of malaria parasites, a strong vaccine candidate, plays a key role during erythrocyte invasion and is a target of host protective immune response. Plasmodium vivax, the most widespread human malaria parasite, is closely related to parasites that infect Asian Old World monkeys, and has been considered to have become a parasite of man by host switch from a macaque malaria parasite. Several Asian monkey parasites have a range of natural hosts. The same parasite species shows different disease manifestations among host species. This suggests that host immune responses to P. vivax-related malaria parasites greatly differ among host species (albeit other factors). It is thus tempting to invoke that a major immune target parasite protein such as MSP-1 underwent unique evolution, depending on parasite species that exhibit difference in host range and host specificity.Results
We performed comparative phylogenetic and population genetic analyses of the gene encoding MSP-1 (msp1) from P. vivax and nine P. vivax-related simian malaria parasites. The inferred phylogenetic tree of msp1 significantly differed from that of the mitochondrial genome, with a striking displacement of P. vivax from a position close to P. cynomolgi in the mitochondrial genome tree to an outlier of Asian monkey parasites. Importantly, positive selection was inferred for two ancestral branches, one leading to P. inui and P. hylobati and the other leading to P. vivax, P. fieldi and P. cynomolgi. This ancestral positive selection was estimated to have occurred three to six million years ago, coinciding with the period of radiation of Asian macaques. Comparisons of msp1 polymorphisms between P. vivax, P. inui and P. cynomolgi revealed that while some positively selected amino acid sites or regions are shared by these parasites, amino acid changes greatly differ, suggesting that diversifying selection is acting species-specifically on msp1.Conclusions
The present results indicate that the msp1 locus of P. vivax and related parasite species has lineage-specific unique evolutionary history with positive selection. P. vivax and related simian malaria parasites offer an interesting system toward understanding host species-dependent adaptive evolution of immune-target surface antigen genes such as msp1. 相似文献156.
Tokuda N Adachi T Adachi Y Higashi M Sharifi K Tuerxun T Sawada T Kondo H Owada Y 《Histochemistry and cell biology》2010,134(5):445-452
Fatty acids and their metabolites regulate immune cell function. The present study was undertaken to examine the detailed
distribution of fatty acid binding proteins (FABPs), the cytosolic chaperones of fatty acids, in mouse peripheral immune organs.
Using immunohistochemistry, FABP7 was localized to the alpha-smooth muscle actin (SMA)+ fibroblastic reticular cells, which construct the stromal reticula in the T cell areas of the peripheral lymph nodes and
spleen. Immunoelectron microscopy showed that FABP7+ cells enclosed the collagen fibers, forming a conduit system, which transport lymph and associated low-molecular-mass proteins.
In contrast, FABP5+ cells were distributed throughout the lymph node and contained well-developed lysosome and phagocytic materials within the
cytoplasm. The mesenteric lymph nodes of FABP7 knockout mice showed normal histological features, but the percentage of CD4+ cells was significantly increased compared with that in wild-type mice. These data indicate that FABP7 may be involved in
T cell homeostasis, possibly by modulating lipid metabolism in fibroblastic reticular cells within the peripheral lymph nodes. 相似文献
157.
Hikosaka K Nakai Y Watanabe Y Tachibana S Arisue N Palacpac NM Toyama T Honma H Horii T Kita K Tanabe K 《Mitochondrion》2011,11(2):273-278
Apicomplexan parasites of the genus Plasmodium, pathogens causing malaria, and the genera Babesia and Theileria, aetiological agents of piroplasmosis, are closely related. However, their mitochondrial (mt) genome structures are highly divergent: Plasmodium has a concatemer of 6-kb unit and Babesia/Theileria a monomer of 6.6- to 8.2-kb with terminal inverted repeats. Fragmentation of ribosomal RNA (rRNA) genes and gene arrangements are remarkably distinctive. To elucidate the evolutionary origin of this structural divergence, we determined the mt genome of Eimeria tenella, pathogens of coccidiosis in domestic fowls. Analysis revealed that E. tenella mt genome was concatemeric with similar protein-coding genes and rRNA gene fragments to Plasmodium. Copy number was 50-fold of the nuclear genome. Evolution of structural divergence in the apicomplexan mt genomes is discussed. 相似文献
158.
Covarrubias C Cortez M Ferreira D Yoshida N 《International journal for parasitology》2007,37(14):1609-1616
Outbreaks of severe acute Chagas’ disease acquired by oral infection, leading to death in some cases, have occurred in recent years. Using the mouse model, we investigated the basis of such virulence by analyzing a Trypanosoma cruzi isolate, SC, from a patient with severe acute clinical symptoms, who was infected by oral route. It has previously been shown that, upon oral inoculation into mice, T. cruzi metacyclic trypomastigotes invade the gastric mucosal epithelium by engaging the stage-specific surface glycoprotein gp82, whereas the surface molecule gp90 functions as a down-modulator of cell invasion. We found that, when orally inoculated into mice, metacyclic forms of the SC isolate, which express high levels of gp90, produced high parasitemias and high mortality, in sharp contrast with the reduced infectivity in vitro. Upon recovery from the mouse stomach 1 h after oral inoculation, the gp90 molecule of the parasites was completely degraded, and their entry into HeLa cells, as well as into Caco-2 cells, was increased. The gp82 molecule was more resistant to digestive action of the gastric juice. Host cell invasion of SC isolate metacyclic trypomastigotes was augmented in the presence of gastric mucin. No alteration in infectivity was observed in T. cruzi strains CL and G which were used as references and which express gp90 molecules resistant to degradation by gastric juice. Taken together, our findings suggest that the exacerbation of T. cruzi infectivity, such as observed upon interaction of the SC isolate with the mouse stomach components, may be responsible for the severity of acute Chagas’ disease that has been reported in outbreaks of oral T. cruzi infection. 相似文献
159.
The crystal structure of the P-protein of the glycine cleavage system from Thermus thermophilus HB8 has been determined. This is the first reported crystal structure of a P-protein, and it reveals that P-proteins do not involve the alpha(2)-type active dimer universally observed in the evolutionarily related pyridoxal 5'-phosphate (PLP)-dependent enzymes. Instead, novel alphabeta-type dimers associate to form an alpha(2)beta(2) tetramer, where the alpha- and beta-subunits are structurally similar and appear to have arisen by gene duplication and subsequent divergence with a loss of one active site. The binding of PLP to the apoenzyme induces large open-closed conformational changes, with residues moving up to 13.5 A. The structure of the complex formed by the holoenzyme bound to an inhibitor, (aminooxy)acetate, suggests residues that may be responsible for substrate recognition. The molecular surface around the lipoamide-binding channel shows conservation of positively charged residues, which are possibly involved in complex formation with the H-protein. These results provide insights into the molecular basis of nonketotic hyperglycinemia. 相似文献
160.
Akao Y Banno Y Nakagawa Y Hasegawa N Kim TJ Murate T Igarashi Y Nozawa Y 《Biochemical and biophysical research communications》2006,342(4):1284-1290
Although most of pharmacological therapies for cancer utilize the apoptotic machinery of the cells, the available anti-cancer drugs are limited due to the ability of prostate cancer cells to escape from the anti-cancer drug-induced apoptosis. A human prostate cancer cell line PC3 is resistant to camptothecin (CPT). To elucidate the mechanism of this resistance, we have examined the involvement of sphingosine kinase (SPHK) and sphingosine 1-phosphate (S1P) receptor in CPT-resistant PC3 and -sensitive LNCaP cells. PC3 cells exhibited higher activity accompanied with higher expression levels of protein and mRNA of SPHK1, and also elevated expression of S1P receptors, S1P(1) and S1P(3), as compared with those of LNCaP cells. The knockdown of SPHK1 by small interfering RNA and inhibition of S1P receptor signaling by pertussis toxin in PC3 cells induced significant inhibition of cell growth, suggesting implication of SPHK1 and S1P receptors in cell proliferation in PC3 cells. Furthermore, the treatment of PC3 cells with CPT was found to induce up-regulation of the SPHK1/S1P signaling by induction of both SPHK1 enzyme and S1P(1)/S1P(3) receptors. These findings strongly suggest that high expression and up-regulation of SPHK1 and S1P receptors protect PC3 cells from the apoptosis induced by CPT. 相似文献