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991.
Hirotaka Imai Nao Hakkaku Ryo Iwamoto Jyunko Suzuki Toshiyuki Suzuki Yoko Tajima Kumiko Konishi Shintaro Minami Shizuko Ichinose Kazuhiro Ishizaka Seiji Shioda Satoru Arata Masuhiro Nishimura Shinsaku Naito Yasuhito Nakagawa 《The Journal of biological chemistry》2009,284(47):32522-32532
Phospholipid hydroperoxide glutathione peroxidase (GPx4) is an intracellular antioxidant enzyme that directly reduces peroxidized phospholipids. GPx4 is strongly expressed in the mitochondria of testis and spermatozoa. We previously found a significant decrease in the expression of GPx4 in spermatozoa from 30% of infertile human males diagnosed with oligoasthenozoospermia (Imai, H., Suzuki, K., Ishizaka, K., Ichinose, S., Oshima, H., Okayasu, I., Emoto, K., Umeda, M., and Nakagawa, Y. (2001) Biol. Reprod. 64, 674–683). To clarify whether defective GPx4 in spermatocytes causes male infertility, we established spermatocyte-specific GPx4 knock-out mice using a Cre-loxP system. All the spermatocyte-specific GPx4 knock-out male mice were found to be infertile despite normal plug formation after mating and displayed a significant decrease in the number of spermatozoa. Isolated epididymal GPx4-null spermatozoa could not fertilize oocytes in vitro. These spermatozoa showed significant reductions of forward motility and the mitochondrial membrane potential. These impairments were accompanied by the structural abnormality, such as a hairpin-like flagella bend at the midpiece and swelling of mitochondria in the spermatozoa. These results demonstrate that the depletion of GPx4 in spermatocytes causes severe abnormalities in spermatozoa. This may be one of the causes of male infertility in mice and humans. 相似文献
992.
993.
We examined brain region-specific changes in monoamines and metabolites, and their ratios, after short-term administration
of antidepressants to rats. Serotonin noradrenaline reuptake inhibitors (SNRIs; duloxetine, venlafaxine, milnacipran) and
a serotonin-selective reuptake inhibitor (SSRI; sertraline) elevated serotonin (5-HT) levels in the midbrain (MB). Duloxetine
and venlafaxine increased 5-HT levels in the brainstem and 5-HT terminal areas, whereas milnacipran and sertraline increased
levels in the brainstem only. Significant reductions in 5-HT turnover were observed in various forebrain regions, including
the hippocampus and hypothalamus, after treatment with all of the tested drugs except for milnacipran. In addition, there
was reduced 5-HT turnover in the dorsolateral frontal cortex (dlFC), the medial prefrontal cortex (mPFC), and both the dlFC
and the mPFC after treatment with duloxetine, sertraline, and venlafaxine, respectively. Venlafaxine significantly increased
dopamine (DA) levels in the nucleus accumbens (NAc) and the substantia nigra and decreased DA turnover in the NAc. Similar
changes were observed after treatment with duloxetine and sertraline in the NAc, whereas milnacipran increased DA levels in
the mPFC. Limited increases in noradrenaline levels were detected after treatment with duloxetine, venlafaxine, or sertraline,
but not after treatment with milnacipran. These results show that SNRIs and SSRIs induced region-specific monoaminergic changes
after short-term treatment. 相似文献
994.
Phylogenetic relationships of seven isolates of the genus Haptoglossa parasitic on terrestrial nematodes within the Peronosporomycetes were analyzed using 18S rDNA sequence data with 21 peronosporomycetes,
2 marine stramenopilous flagellates, and 2 hyphochytridiomycetes. The marine stramenopilous flagellates and hyphochytridiomycetes
were used as the outgroup. All Haptoglossa isolates formed a monophyletic clade and clustered with the marine genus Eurychasma. The clade of Haptoglossa and Eurychasma formed a sister-group to the clade that consisted of all other peronosporomycetes. These results suggest that the genus Haptoglossa and other terrestrial peronosporomycetes included in the two subclasses, the Saprolegniomycetidae and the Peronosporomycetidae,
might have originally adapted to the terrestrial environment individually. In the maximum-likelihood (ML) analysis, the Haptoglossa clade was divided into three subclades, one aplanosporic species clade and two zoosporic species clades. Phylogenetic analyses
of combined 18S rDNA and cox2 genes among five species of Haptoglossa supported the results of the ML analysis using 18S rDNA and suggested that zoosporic species may be separated into two lineages.
This topology of the analysis may suggest that aplanosporic species diverged from zoosporic species. 相似文献
995.
Taiga Kasuya Yukinori Yamamoto Haruo Sakamoto Seiji Takehashi Tamotsu Hoshino Takahito Kobayashi 《Mycoscience》2009,50(2):84-93
Geastrum berkeleyi, G. fornicatum, and G. minimum are newly recorded from Japan. A peristome of G. fornicatum has hitherto been described as indistinct, whereas the Japanese specimens have a well-delimited, fibrillose peristome. Geastrum minus, reported for the first time from Japan by Sanshi Imai, represents G. quadrifidum. Macroscopic and microscopic features of those four taxa are described and illustrated based on Japanese specimens. 相似文献
996.
Two taxa of the genus Pluteus, i.e., Pluteus magnus and Pluteus podospileus f. podospileus, are newly recorded from Japan. The macroscopic and microscopic features of these two species are described and illustrated. 相似文献
997.
Seiji Miyauchi 《生物化学与生物物理学报:生物膜》2010,1798(6):1164-4037
Pyroglutamate, also known as 5-oxoproline, is a structural analog of proline. This amino acid derivative is a byproduct of glutathione metabolism, and is reabsorbed efficiently in kidney by Na+-coupled transport mechanisms. Previous studies have focused on potential participation of amino acid transport systems in renal reabsorption of this compound. Here we show that it is not the amino acid transport systems but instead the Na+-coupled monocarboxylate transporter SLC5A8 that plays a predominant role in this reabsorptive process. Expression of cloned human and mouse SLC5A8 in mammalian cells induces Na+-dependent transport of pyroglutamate that is inhibitable by various SLC5A8 substrates. SLC5A8-mediated transport of pyroglutamate is saturable with a Michaelis constant of 0.36 ± 0.04 mM. Na+-activation of the transport process exhibits sigmoidal kinetics with a Hill coefficient of 1.8 ± 0.4, indicating involvement of more than one Na+ in the activation process. Expression of SLC5A8 in Xenopuslaevis oocytes induces Na+-dependent inward currents in the presence of pyroglutamate under voltage-clamp conditions. The concentration of pyroglutamate necessary for induction of half-maximal current is 0.19 ± 0.01 mM. The Na+-activation kinetics is sigmoidal with a Hill coefficient of 2.3 ± 0.2. Ibuprofen, a blocker of SLC5A8, suppressed pyroglutamate-induced currents in SLC5A8-expressing oocytes; the concentration of the blocker necessary for causing half-maximal inhibition is 14 ± 1 μM. The involvement of SLC5A8 can be demonstrated in rabbit renal brush border membrane vesicles by showing that the Na+-dependent uptake of pyroglutamate in these vesicles is inhibitable by known substrates of SLC5A8. The Na+ gradient-driven pyroglutamate uptake was stimulated by an inside-negative K+ diffusion potential induced by valinomycin, showing that the uptake process is electrogenic. 相似文献
998.
999.
Seiji Matsumoto Takeshi Kon Motoomi Yamaguchi Hirohiko Takeshima Yuji Yamazaki Takahiko Mukai Kaoru Kuriiwa Masanori Kohda Mutsumi Nishida 《Ichthyological Research》2010,57(1):71-77
The swamp eel Monopterus albus is widely distributed in tropical and subtropical freshwaters ranging from Southeast Asia to East Asia, and is unique in
its ability to breathe air through the buccal mucosa. To examine the genetic structure of this widespread species, molecular
phylogenetic analyses of mitochondrial 16S rRNA sequence (514 bp) were conducted for 84 specimens from 13 localities in Southeast
and East Asia. The analyses showed clearly that this species can be genetically delineated into three clades based on geographical
populations [China–Japan (Honshu + Kyushu), Ryukyu Islands, and Southeast Asia clades], with each clade exhibiting its own
reproductive behavior. Therefore, “M. albus” is believed to be composed of at least three species. The Southeast Asia clade with the highest genetic diversity may include
more species. The Ryukyu clade was estimated to have diverged more than 5.7 million years ago, suggesting that the Ryukyuan
“M. albus” is native. In contrast, in the China–Japan clade, all haplotypes from Japan were closely related to those from China, suggesting
artificial introduction(s). 相似文献
1000.
Seiji Sonobe Kazue Aoyama Chihiro Suzuki Ko-hei Saito Kumiko Nagata Teruo Shimmen Yoko Nagata 《Extremophiles : life under extreme conditions》2010,14(4):403-407
Pyrobaculum islandicum is a hyperthermophilic archaeon. P. islandicum cells have been suggested to multiply by constriction, budding and branching, as no septa were observed in cells by phase-contrast
light microscopy. In this study, we observed the cells using transmission electron microscopy, scanning electron microscopy,
and light microscopy with dark-field image analyses, and we report binary fission via septum formation to be the main mode
of P. islandicum’s proliferation. “Long cells” reported previously were found to comprise several cylindrical cells that align in tandem. 相似文献