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81.
Mitsue Shibata Satoshi Kikuchi Hiroshi Tanaka Masahiro Sueyoshi Hiroshi Yoshimaru Kaoru Niiyama 《Ecological Research》2009,24(1):1-9
The effects of local population density, sex morph [protogynous (PG) or protandrous (PA)], and individual tree size on the
demographic processes of seed production were investigated in a heterodichogamous maple, Acer mono Maxim. var. Marmoratum (Nichols.) Hara f. dissectum, in a temperate forest of Japan. As the distance from conspecific reproductive adults increased, the percentage of immature
seed fall and empty seeds increased significantly, indicating higher pollination success along with local population density.
Although the difference was not distinct, pollination success was affected by the local population density of the reciprocal
sex morph rather than that of both sex morphs. The trees at higher local population density sites suffered higher seed mortality
due to predation and decay, and tended to produce smaller seeds. Thus, the impacts of local population density operated both
positively and negatively on reproduction. As a factor of individual traits, tree size scarcely affected any demographic processes.
On the other hand, sex morph did affect pollination success. Trees of PG type had lower immature seed fall than those of PA
type, suggesting that the former has higher efficiency of pollen acceptance than the latter. The results on seed demography
presented here partly support previous suggestions that heterodichogamous plants exhibit reciprocal cross-pollination and
gender specialization as reproductive traits. 相似文献
82.
83.
Fumiyuki Nakagawa Katsutaro Morino Satoshi Ugi Atsushi Ishikado Keiko Kondo Daisuke Sato Shiho Konno Ken-ichi Nemoto Chisato Kusunoki Osamu Sekine Akihiro Sunagawa Masanori Kawamura Noriko Inoue Yoshihiko Nishio Hiroshi Maegawa 《Biochemical and biophysical research communications》2014
It has recently been reported that expression of heme oxygenase-1 (HO-1) plays a protective role against many diseases. Furthermore, n-3 polyunsaturated fatty acids (PUFAs) were shown to induce HO-1 expression in several cells in vitro, and in a few cases also in vivo. However, very few reports have demonstrated that n-3 PUFAs induce HO-1 in vivo. 相似文献
84.
The industrial yeast Candida utilis can grow on media containing xylose as sole carbon source, but cannot ferment it to ethanol. The deficiency might be due to the low activity of NADPH-preferring xylose reductase (XR) and NAD(+)-dependent xylitol dehydogenase (XDH), which convert xylose to xylulose, because C. utilis can ferment xylulose. We introduced multiple site-directed mutations in the coenzyme binding sites of XR and XDH derived from the xylose-fermenting yeast Candida shehatae to alter their coenzyme specificities. Several combinations of recombinant and native XRs and XDHs were tested. Highest productivity was observed in a strain expressing CsheXR K275R/N277D (NADH-preferring) and native CsheXDH (NAD(+)-dependent), which produced 17.4 g/L of ethanol from 50 g/L of xylose in 20 h. Analysis of the genes responsible for ethanol production from the xylose capacity of C. utilis indicated that the introduction of CsheXDH was essential, while overexpression of CsheXR K275R/N277D improved efficiency of ethanol production. 相似文献
85.
Satoshi Oguchi Hiroyuki Saito Masayoshi Tsukahara Haruhiko Tsumura 《Cytotechnology》2006,52(3):199-207
Controlling cell proliferation during cell culturing is an effective way to improve the production yield in mammalian cell
culture. We examined the effect of temperature shifts (TS) under pH control conditions in Chinese hamster ovary cells. When
we shifted the culture temperature from 37 °C to 31 °C before a stationary phase at pH 6.8 (TS/pH 6.8), cell viability remained
high, and the final human monoclonal antibody (hMab) concentration increased to 2.3 times that in the culture remaining at
37 °C. However, there were no significant effects on the cell viability or production yield with the same TS at pH 7.0 (TS/pH
7.0). The average specific hMab productivity and mRNA level of TS/pH 7.0 were the same as that of TS/pH 6.8. The control of
cell growth by the TS or the addition of rapamycin was effective in the maintenance of cell viability, but there was no significant
increase of the average specific hMab productivity in the culture where cell proliferation was controlled with rapamycin.
The hMab mRNA concentration decreased to 55%–65% at a 37 °C culture with the addition of actinomycin D. In contrast, actinomycin
D did not affect the mRNA level in the TS culture. This result suggested that the increase in the mRNA level in the TS condition
was caused by an increase in mRNA stability. In this study, we show that TS can produce two unrelated effects: a prolongation
of cell longevity and an improvement in mRNA stability. 相似文献
86.
87.
nanos1: a mouse nanos gene expressed in the central nervous system is dispensable for normal development 总被引:2,自引:0,他引:2
Haraguchi S Tsuda M Kitajima S Sasaoka Y Nomura-Kitabayashid A Kurokawa K Saga Y 《Mechanisms of development》2003,120(6):721-731
A mouse nanos (nanos1) gene was cloned and its function was examined by generating a gene-knockout mouse. The nanos1 gene encodes an RNA-binding protein, which contains a putative zinc-finger motif that exhibits similarity with other nanos-class genes in vertebrates and invertebrates. Although nanos1 is not detected in primordial germ cells, it is observed in seminiferous tubules of mature testis. Interestingly, maternally expressed nanos1 is observed in substantial amounts in oocytes, but the amount of maternal RNA is rapidly reduced after fertilization, and the transient zygotic nanos1 expression is observed in eight-cell embryos. At 12.5 days postcoitum, nanos1 is re-expressed in the central nervous system and the expression continues in the adult brain, in which the hippocampal formation is the predominant region. The nanos1 -deficient mice develop to term without any detectable abnormality and they are fertile. No significant neural defect is observed in terms of their behavior to date. 相似文献
88.
Onizuka T Endo S Akiyama H Kanai S Hirano M Yokota A Tanaka S Miyasaka H 《Plant & cell physiology》2004,45(10):1390-1395
The operon encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the cyanobacterium Synechococcus sp. PCC7002 contains three rbc genes, rbcL, rbcX and rbcS, in this order. Introduction of translational frameshift into the rbcX gene resulted in a significant decrease in the production of large (RbcL) and small (RbcS) subunits of the Rubisco protein in Synechococcus sp. PCC7002 and in Escherichia coli. To investigate the function of the rbcX gene product (RbcX), we constructed the expression plasmid for the rbcX gene and examined the effects of RbcX on the recombinant Rubisco production in Escherichia coli. The coexpression experiments revealed that RbcX had marked effects on the production of large and small subunits of Rubisco without any significant influence on the mRNA level of rbc genes and/or the post-translational assembly of the Rubisco protein. The present rbcX coexpression system provides a novel and useful method for investigating the Rubisco maturation pathway. 相似文献
89.
Miyako Kusano Atsushi Fukushima Henning Redestig Makoto Kobayashi Hitomi Otsuki Hitoshi Onouchi Satoshi Naito Masami Yokota Hirai Kazuki Saito 《Amino acids》2010,39(4):1013-1021
Methionine (Met) is an essential amino acid for all organisms. In plants, Met also functions as a precursor of plant hormones,
polyamines, and defense metabolites. The regulatory mechanism of Met biosynthesis is highly complex and, despite its great
importance, remains unclear. To investigate how accumulation of Met influences metabolism as a whole in Arabidopsis, three methionine over-accumulation (mto) mutants were examined using a gas chromatography–mass spectrometry-based metabolomics approach. Multivariate statistical
analyses of the three mto mutants (mto1, mto2, and mto3) revealed distinct metabolomic phenotypes. Orthogonal projection to latent structures–discriminant analysis highlighted discriminative
metabolites contributing to the separation of each mutant and the corresponding control samples. Though Met accumulation in
mto1 had no dramatic effect on other metabolic pathways except for the aspartate family, metabolite profiles of mto2 and mto3 indicated that several extensive pathways were affected in addition to over-accumulation of Met. The pronounced changes
in metabolic pathways in both mto2 and mto3 were associated with polyamines. The findings suggest that our metabolomics approach not only can reveal the impact of Met
over-accumulation on metabolism, but also may provide clues to identify crucial pathways for regulation of metabolism in plants. 相似文献
90.
The phosphorylation of two isozymes (alpha(+) and alpha) of (Na+ + K+)-ATPase by 32Pi was studied under equilibrium conditions in various enzyme preparations from rat medulla oblongata, rat cerebral cortex, rat cerebellum, rat kidney, guinea pig kidney, and rabbit kidney. In ouabain-sensitive (Na+ + K+)-ATPases such as the brain, guinea pig kidney, and rabbit kidney enzymes, ouabain stimulated the Mg2+-dependent phosphorylation at lower concentrations, while a higher concentration was required for the stimulation of rat kidney (Na+ + K+)-ATPase, an ouabain-insensitive enzyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that two isozymes of the brain (Na+ + K+)-ATPase were also phosphorylated by 32Pi in the presence of ouabain. The properties of the phosphorylation were compared between the medullar oblongata (referred to as alpha(+] and the kidney (referred to as alpha) (Na+ + K+)-ATPases. The steady-state level of phosphorylation was achieved faster in the kidney enzymes than in the medulla oblongata enzyme. Phosphorylation without ouabain was greater in the kidney enzymes than in the brain enzymes. Furthermore, the former enzymes were inhibited by K+ much more than the latter. These findings suggest that the two isozymes of (Na+ + K+)-ATPase differ in their conformational changes during enzyme turnover. 相似文献