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51.
52.
Kidokoro Y 《Neuro-Signals》2003,12(1):13-30
The roles of SNARE proteins, i.e. neuronal Synaptobrevin (n-Syb), SNAP-25 and Syntaxin 1A (Syx 1A), and Synaptotagmin I (Syt I) in synaptic transmission have been studied in situ using mutant embryos or larvae that lack these molecules or have alterations in them. Because of the ease of genetic manipulation, the Drosophila neuromuscular synapse is widely used for these studies. The functional properties of synaptic transmission have been studied in mutant embryos using the patch-clamp technique, and in larvae by recording with microelectrodes. A major vesicular membrane protein, n-Syb, is indispensable for nerve-evoked synaptic transmission. Spontaneous synaptic currents (minis), however, are present even in embryos totally lacking n-Syb (N-SYB). Furthermore, Ca(2+)-independent enhancement of mini frequency induced by hypertonic sucrose solutions (hypertonicity response) is totally absent in N-SYB. Embryos that have defects in SNAP-25 (SNAP-25) have similar but milder phenotypes than N-SYB. The phenotype in synaptic transmission was most severe in the synapse lacking Syx 1A. Neither nerve-evoked synaptic currents nor minis occur in embryos lacking Syx 1A (SYX 1A). No hypertonicity response was observed in them. Syt I binds Ca(2+) in vitro and probably serves as a Ca(2+) sensor for nerve-evoked synaptic transmission, since nerve-evoked synaptic currents were greatly reduced in embryos lacking Syt I (SYT I). Also, Syt I has a role in vesicle recycling. Interestingly, the Ca(2+)-independent hypertonicity response is also greatly reduced in SYT I. Minis persist in mutant embryos lacking any of these proteins (n-Syb, SNAP-25 and Syt I), except Syx, suggesting that minis have a distinct fusion mechanism from that for fast and synchronized release. It appears that these SNARE proteins and Syt I are coordinated for fast vesicle fusion. Minis, on the other hand, do not require SNARE complex nor Syt I, but Syx is absolutely required for vesicle fusion. The SNARE complex and Syt I are indispensable for the hypertonicity response. None of these molecules seem to serve for selective docking of synaptic vesicles to the release site. For further studies on synaptic transmission, the Drosophila neuromuscular synapse will continue to be a useful model. 相似文献
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Multiple myeloma (MM) is a neoplasm of a terminally differentiated B-cell. Human myeloma cell lines were shown to be suitable model systems for use in various fields of the biological sciences. Within the last 20 years more than 100 cell lines have been established. So-called 'myeloma cell lines' have been previously reported and are still widely used which are in reality Epstein-Barr virus (EBV)-positive B-lymphoblastoid cell lines. The presence of the EBV-genome in residual normal B-cells provides them with a selective growth advantage after explantation. Cell lines represent an extremely important resource for research in a variety of fields and disciplines. As the cell lines are used as in vitro model systems in lieu of primary material, it is crucial that the cells in the culture flasks faithfully correspond to the purported objects of study. On closer examination, the use of false cell lines may be seen to invalidate a significant percentage of scientific work, or at least cast doubts on the relevance of these in vitro results to the cell type or tumor in vivo. Ultimately, use of cross-contaminated cell lines is a waste of human and material resources. Henceforth, it should be mandatory to prove the proper derivation of each new cell line by comparing DNA fingerprints or karyotypes of the patient's primary cells and the cultured cells. The availability of well characterized and authenticated bona fide MM cell lines is of great importance for the study of the biology, etiology and treatment of the disease. 相似文献
55.
Structural features of N-glycans linked to glycoproteins from oil palm pollen, an allergenic pollen*
Kimura Y Yoshiie T Kit WK Maeda M Kimura M Tan SH 《Bioscience, biotechnology, and biochemistry》2003,67(10):2232-2239
The pollen of oil palm (Elaeis guineensis Jacq.) is a strong allergen and causes severe pollinosis in Malaysia and Singapore. In the previous study (Biosci. Biotechnol. Biochem., 64, 820-827 (2002)), from the oil palm pollens, we purified an antigenic glycoprotein (Ela g Bd 31 K), which is recognized by IgE from palm pollinosis patients. In this report, we describe the structural analysis of sugar chains linked to palm pollen glycoproteins to confirm the ubiquitous occurrence of antigenic N-glycans in the allergenic pollen. N-Glycans liberated from the pollen glycoprotein mixture by hydrazinolysis were labeled with 2-aminopyridine followed by purification with a combination of size-fractionation HPLC and reversed-phase HPLC. The structures of the PA-sugar chains were analyzed by a combination of two-dimensional sugar chain mapping, electrospray ionization mass spectrometry (ESI-MS), and tandem MS analysis, as well as exoglycosidase digestions. The antigenic N-glycan bearing alpha1-3 fucose and/or beta1-2 xylose residues accounts for 36.9% of total N-glycans: GlcNAc2Man3Xyl1Fuc1GlcNAc2 (24.6%), GlcNAc2Man3Xyl1GlcNAc2 (4.4%), Man3Xyl1Fuc1-GlcNAc2 (1.1%), GlcNAc1Man3Xyl1Fuc1GlcNAc2 (5.6%), and GlcNAc1Man3Xyl1GlcNAc2 (1.2%). The remaining 63.1% of the total N-glycans belong to the high-mannose type structure: Man9GlcNAc2 (5.8%), Man8GlcNAc2 (32.1%), Man7GlcNAc2 (19.9%), Man6GlcNAc2 (5.3%). 相似文献
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57.
Ismail AB Yoshinobu T Iwasaki H Sugihara H Yukimasa T Hirata I Iwata H 《Biosensors & bioelectronics》2003,18(12):1509-1514
This article reports an investigation on light-addressable potentiometric sensor (LAPS) to be used as a possible biological cell-semiconductor hybrid that will enable us to make an interface between the physical and biological system. To increase the surface potential sensitivity, we used a LAPS structure with single insulator (SiO2) coated with poly-L-ornithine and laminin (PLOL) on Si. Efficient culturing of PC-12 and nerve cells of Lymnaea stagnalis on PLOL-coated Si3N4 and SiO2 was achieved. The thickness of the PLOL layer was found to be about 4 nm by the atomic force microscope (AFM) measurement. Using the advantage of this thin layer of PLOL, we compared the performance of a novel structure to the previously reported "PLOL-coated Si3N4/SiO2/Si" structure. Due to high insulating capacitance, the photocurrent response of the novel LAPS was found to be very steep. As a result, higher sensitivity was achieved. This steepness did not degrade during 10 days when the sensor surface was kept in contact with the cell culture medium and environment. The thickness of PLOL layer, its ability to improve the biological cell adhesion, enhanced sensitivity, and experiment with simulated neural action potential (AP) applied to the novel LAPS show a good promise for LAPS to be a biological cell-semiconductor hybrid. 相似文献
58.
At Drosophila neuromuscular junctions, there are two synaptic vesicle pools, namely the exo/endo cycling pool (ECP) and the reserve pool (RP). We studied the recruitment process from RP using a fluorescent dye, FMI-43. During high-frequency nerve stimulation, vesicles in RP were recruited for release, and endocytosed vesicles were incorporated into both pools, whereas with low-frequency stimulation, vesicles were incorporated into and released from ECP. Release of vesicles from RP was detected electrophysiologically after emptying vesicles in the ECP of transmitter by a H+ pump inhibitor. Recruitment from RP was depressed by inhibitors of steps in the cAMP/PKA cascade and enhanced by their activators. In rutabaga (rut) with low cAMP levels, mobilization of vesicles from RP during tetanic stimulation was depressed, while it was enhanced in dunce (dnc) with high cAMP levels. 相似文献
59.
Most bryophytes produce tetrahedral spore tetrads. However, linear spore tetrads have been reported to occur in Conocephalum japonicum (Thunb.) Grolle. In this study, the distribution of microtubules (MTs) during meiosis in C. japonicum was examined to determine the division pattern resulting in a linear tetrad. Spore mother cells in the pre-meiotic stage
were cylindrical with randomly distributed cytoplasmic MTs. In the prophase-metaphase transition, spindle MTs replaced cytoplasmic
MTs and a barrel-shaped spindle with two flattened poles developed. Cortical MT arrays were not detectable throughout meiosis.
Although a phragmoplast appeared between sister nuclei in telophase-I, it disappeared without expanding to the parental cell
wall. Metaphase-II spindles oriented parallel to the long axis of the cell and in tandem to each other resulted in a linear
arrangement of telophase nuclei. Radial arrays of MTs developed from the nuclear surfaces and three phragmoplasts appeared
among the four nuclei to produce four spores. Two phragmoplasts separating the paired sister nuclei appeared prior to the
appearance of a phragmoplast between non-sister nuclei. The MT cycle is basically the same as that reported in meiosis of
C. conicum, which produces non-linear tetrads. A morphometric study indicated that the difference in the division pattern between C. conicum and C. japonicum is due to a difference in the shape of spore mother cells. The cylindrical shape of sporocytes of C. japonicum restricts the orientation of spindles and phragmoplasts so that the four resultant spores are arranged linearly.
Received: 22 April 1998 / Accepted: 15 May 1998 相似文献
60.
Yosuke?Shida Kaori?Yamaguchi Mikiko?Nitta Ayana?Nakamura Machiko?Takahashi Shun-ichi?Kidokoro Kazuki?Mori Kosuke?Tashiro Satoru?Kuhara Tomohiko?Matsuzawa Katsuro?Yaoi Yasumitsu?Sakamoto Nobutada?Tanaka Yasushi?Morikawa Wataru?OgasawaraEmail author 《Biotechnology for biofuels》2015,8(1):230