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101.
Takanori Yanagi Kenta Ito Akiha Nishihara Reika Minamino Shoko Mori Masayuki Sumida Chikara Hashimoto 《Development, growth & differentiation》2015,57(3):218-231
The dorsal blastopore lip (known as the Spemann organizer) is important for making the body plan in amphibian gastrulation. The organizer is believed to involute inward and migrate animally to make physical contact with the prospective head neuroectoderm at the blastocoel roof of mid‐ to late‐gastrula. However, we found that this physical contact was already established at the equatorial region of very early gastrula in a wide variety of amphibian species. Here we propose a unified model of amphibian gastrulation movement. In the model, the organizer is present at the blastocoel roof of blastulae, moves vegetally to locate at the region that lies from the blastocoel floor to the dorsal lip at the onset of gastrulation. The organizer located at the blastocoel floor contributes to the anterior axial mesoderm including the prechordal plate, and the organizer at the dorsal lip ends up as the posterior axial mesoderm. During the early step of gastrulation, the anterior organizer moves to establish the physical contact with the prospective neuroectoderm through the “subduction and zippering” movements. Subduction makes a trench between the anterior organizer and the prospective neuroectoderm, and the tissues face each other via the trench. Zippering movement, with forming Brachet's cleft, gradually closes the gap to establish the contact between them. The contact is completed at the equator of early gastrulae and it continues throughout the gastrulation. After the contact is established, the dorsal axis is formed posteriorly, but not anteriorly. The model also implies the possibility of constructing a common model of gastrulation among chordate species. 相似文献
102.
Masayuki Adachi Masatomo So Kazumasa Sakurai József Kardos Yuji Goto 《The Journal of biological chemistry》2015,290(29):18134-18145
Although amyloid fibrils and amorphous aggregates are two types of aggregates formed by denatured proteins, their relationship currently remains unclear. We used β2-microglobulin (β2m), a protein responsible for dialysis-related amyloidosis, to clarify the mechanism by which proteins form either amyloid fibrils or amorphous aggregates. When ultrasonication was used to accelerate the spontaneous fibrillation of β2m at pH 2.0, the effects observed depended on ultrasonic power; although stronger ultrasonic power effectively accelerated fibrillation, excessively strong ultrasonic power decreased the amount of fibrils formed, as monitored by thioflavin T fluorescence. An analysis of the products formed indicated that excessively strong ultrasonic power generated fibrillar aggregates that retained β-structures but without high efficiency as seeds. On the other hand, when the spontaneous fibrillation of β2m was induced at higher concentrations of NaCl at pH 2.0 with stirring, amorphous aggregates became more dominant than amyloid fibrils. These apparent complexities in fibrillation were explained comprehensively by a competitive mechanism in which supersaturation-limited reactions competed with supersaturation-unlimited reactions. We link the kinetics of protein aggregation and a conformational phase diagram, in which supersaturation played important roles. 相似文献
103.
Neural progenitor cells and developing neurons show periodic, synchronous Ca2+ rises even before synapse formation, and the origin of the synchronous activity remains unknown. Here, fluorescence measurement revealed that the membrane potential of the nuclear envelope, which forms an intracellular Ca2+ store, changed with a release of Ca2+ and generated spontaneous, periodic bursts of fluctuations in potential. Furthermore, changes in the nuclear envelope’s potential underlay spike burst generations. These results support the model that voltage fluctuations of the nuclear envelope synchronize Ca2+ release between cells and also function as a current noise generator to cause synchronous burst discharges. 相似文献
104.
Transforming growth factor-β (TGF-β) is a pleiotropic cytokine that plays a critical role in modulating immune response and
inflammation. We have investigated the effects of TGF-β1 on the expression of type IV collagenases, matrix metalloproteinase
(MMP)-2 and MMP-9, in mouse peritoneal macrophages. TGF-β1 alone enhanced the secretion of MMP-9, while it blocked lipopolysaccharide
(LPS)-stimulated MMP-9 production. We have shown that this biphasic effect of TGF-β1 is exerted at the mRNA level of the MMP-9
gene. Although TGF-β1 increased both basal and LPS-induced MMP-2 production at the protein and mRNA levels, the extent of
the increase was smaller in LPS-activated macrophages than in control macrophages. The expression of type I and type II receptors
for TGF-β was significantly decreased upon activation, suggesting that the lesser effect of TGF-β1 in activated macrophages
may result from the decreased expression of TGF-β receptors. In addition, the expression of endogenous TGF-β1 mRNA was decreased
significantly in activated macrophages. These findings suggest that activated macrophages not only produce less TGF-β1, but
also respond less well to TGF-β to provide for inflammatory response. 相似文献
105.
Hydrogen-Deuterium Exchange Effects on β-Endorphin Release from AtT20 Murine Pituitary Tumor Cells 下载免费PDF全文
Masayuki Ikeda Shigeru Suzuki Masahiro Kishio Moritoshi Hirono Takashi Sugiyama Junko Matsuura Teppei Suzuki Takayuki Sota Charles N. Allen Shiro Konishi Tohru Yoshioka 《Biophysical journal》2004,86(1):565-575
Abundant evidences demonstrate that deuterium oxide (D2O) modulates various secretory activities, but specific mechanisms remain unclear. Using AtT20 cells, we examined effects of D2O on physiological processes underlying β-endorphin release. Immunofluorescent confocal microscopy demonstrated that 90% D2O buffer increased the amount of actin filament in cell somas and decreased it in cell processes, whereas β-tubulin was not affected. Ca2+ imaging demonstrated that high-K+-induced Ca2+ influx was not affected during D2O treatment, but was completely inhibited upon D2O washout. The H2O/D2O replacement in internal solutions of patch electrodes reduced Ca2+ currents evoked by depolarizing voltage steps, whereas additional extracellular H2O/D2O replacement recovered the currents, suggesting that D2O gradient across plasma membrane is critical for Ca2+ channel kinetics. Radioimmunoassay of high-K+-induced β-endorphin release demonstrated an increase during D2O treatment and a decrease upon D2O washout. These results demonstrate that the H2O-to-D2O-induced increase in β-endorphin release corresponded with the redistribution of actin, and the D2O-to-H2O-induced decrease in β-endorphin release corresponded with the inhibition of voltage-sensitive Ca2+ channels. The computer modeling suggests that the differences in the zero-point vibrational energy between protonated and deuterated amino acids produce an asymmetric distribution of these amino acids upon D2O washout and this causes the dysfunction of Ca2+ channels. 相似文献
106.
107.
Yuki Sakamoto Jun Yamazaki Takayuki Yamada Jun Yokoyama Yuki Ogura‐Tsujita Masayuki Maki 《Plant Species Biology》2017,32(1):81-86
The diversity of mycorrhizal fungi among four Japanese Cephalanthera (Orchidaceae) species was examined at a total of seven sites, based on sequence variation in nuclear ribosomal DNA. This is the first report to detect mycorrhizal fungi in C. subaphylla. Two patterns of mycorrhizal associations were confirmed from our results. C. falcata has lower fungal specificity, associating with Russulaceae, Sebacinales and Thelephoraceae. By contrast, the three Cephalanthera species C. erecta, C. subaphylla, and C. longifolia were associated mainly with Thelephoraceae fungi. There is no large difference found in mycobionts between green and albino individuals of C. falcata and no distinct preference of Japanese Cephalanthera species for a specific fungal group of Thelephoraceae. 相似文献
108.
Development and characterization of EST‐SSR markers in an East Asian temperate plant genus Diabelia (Caprifoliaceae) 下载免费PDF全文
Kun‐Kun Zhao Hua‐Feng Wang Shota Sakaguchi Sven Landrein Yuji Isagi Masayuki Maki Zhi‐Xin Zhu 《Plant Species Biology》2017,32(3):247-251
A set of expressed sequence tag (EST) simple sequence repeat (SSR) markers were developed and characterized using next‐generation sequencing technology for the genus Diabelia (Caprifoliaceae). De novo assembly of RNA‐seq reads resulted in 58 669 contigs with the N50 length of 1211 bp. A total of 2746 contigs were identified to harbor SSR motifs, of which 48 primer pairs were designed and 11 were shown to be polymorphic across three morphospecies of Diabelia. When evaluated with 30 individuals, the number of alleles per locus ranged from 2 to 11 and the expected heterozygosity varied from 0.399 to 0.873, respectively. Distance‐based clustering indicated that the EST‐SSR markers can provide sufficient power to distinguish the three species (or populations). These markers will be useful for evaluating the range‐wide genetic diversity of each species and examining genetic divergence and gene flow between the three species. 相似文献
109.
A multispecific monoclonal antibody G2 recognizes at least three completely different epitope sequences with high affinity 下载免费PDF全文
Md. Nuruddin Mahmud Masayuki Oda Daiki Usui Yasuo Inoshima Naotaka Ishiguro Yuji O. Kamatari 《Protein science : a publication of the Protein Society》2017,26(11):2162-2169
A monoclonal antibody (mAb) G2 possesses an unusual characteristic of reacting with at least three proteins (ATP6V1C1, SEPT3, and C6H10orf76) other than its original antigen, chicken prion protein (ChPrP). The epitopes on ChPrP and ATP6V1C1 have been identified previously. In this study, we identified the epitope in the third protein, SEPT3. Interestingly, there was no amino acid sequence similarity among the epitopes on the three proteins. These epitopes had high binding affinities to G2 (K D = ~10?7 M for monovalent binding and K D = ~10?9 M for divalent binding), as determined using a SPR biosensor. This is the first report on a three‐in‐one mAb recognizing completely different epitope sequences with high affinity. Additionally, competitive ELISA indicated that the binding sites on G2, specific for the three different epitopes, overlapped, suggesting that the antigen‐binding site may be flexible in the free form and capable of adapting to at least three different conformations to enable interactions with three different antigens. 相似文献
110.
The neuroprotective effect of latanoprost acts via klotho‐mediated suppression of calpain activation after optic nerve transection 下载免费PDF全文