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51.
Role for brain-derived neurotrophic factor in learning and memory 总被引:23,自引:0,他引:23
In addition to its actions on neuronal survival and differentiation, brain-derived neurotrophic factor (BDNF) has a role in the regulation of synaptic strength. Long-term potentiation, a form of synaptic plasticity, is markedly impaired in BDNF mutant mice, but the changes were restored by the re-expression of BDNF. BDNF also influences the development of patterned connections and the growth and complexity of dendrites in the cerebral cortex. These results suggest a role for BDNF in learning and memory processes, since memory acquisition is considered to involve both short-term changes in electrical properties and long-term structural alterations in synapses. Memory acquisition is associated with an increase in BDNF mRNA and TrkB receptor activation in specific brain areas. Moreover, the pharmacologic and genetic deprivation of BDNF or its receptor TrkB results in severe impairment of learning and memory in mice, rats and chicks. The effect of BDNF on learning and memory may be linked to the modulation of NMDA and non-NMDA receptor functions as well as the expression of synaptic proteins required for exocytosis. Activation of the mitogen-associated protein kinase and/or phosphatidylinositol 3-kinase signaling pathways may be involved in BDNF-dependent learning and memory formation. It is concluded that BDNF/TrkB signaling plays an important role in learning and memory. 相似文献
52.
Takahashi T Kobayakawa Y Muneoka Y Fujisawa Y Mohri S Hatta M Shimizu H Fujisawa T Sugiyama T Takahara M Yanagi K Koizumi O 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,135(2):309-324
KPNAYKGKLPIGLWamide, a novel member of the GLWamide peptide family, was isolated from Hydra magnipapillata. The purification was monitored with a bioassay: contraction of the retractor muscle of a sea anemone, Anthopleura fuscoviridis. The new peptide, termed Hym-370, is longer than the other GLWamides previously isolated from H. magnipapillata and another sea anemone, A. elegantissima. The amino acid sequence of Hym-370 is six residues longer at its N-terminal than a putative sequence previously deduced from the cDNA encoding the precursor protein. The new longer isoform, like the shorter GLWamides, evoked concentration-dependent muscle contractions in both H. magnipapillata and A. fuscoviridis. In contrast, Hym-248, one of the shorter GLWamide peptides, specifically induced contraction of the endodermal muscles in H. magnipapillata. This is the first case in which a member of the hydra GLWamide family (Hym-GLWamides) has exhibited an activity not shared by the others. Polyclonal antibodies were raised to the common C-terminal tripeptide GLWamide and were used in immunohistochemistry to localize the GLWamides in the tissue of two species of hydra, H. magnipapillata and H. oligactis, and one species of sea anemone, A. fuscoviridis. In each case, nerve cells were specifically labeled. These results suggest that the GLWamides are ubiquitous among cnidarians and are involved in regulating the excitability of specific muscles. 相似文献
53.
In 1989 a new gelada baboon (Theropithecus gelada) population was found in Arsi, on the opposite side of the Rift Valley to that of the known gelada populations of Semien
and Showa. Previous comparisons of units of the band at Gado Goro, Arsi, in the same season in consecutive years, indicated
that unit structure is less stable among Arsi geladas as compared to the Semien population. Gelada units of the band at Gado-Goro
were studied for 7 months in order to investigate the processes of social changes. Changes in unit structure were observed.
Provisioning was carried out for 1.5 months at the beginning of the 7-month study period, in order to capture and obtain blood
samples from the geladas. Following this, changes in male leadership of some units were observed, presumably as a consequence
of the capture. However, natural changes also occurred. One change in unit structure occurred after a female gave birth, and
changes in another unit occurred after the disappearance of the leader male. These changes involved female desertion of a
unit, her subsequent transfer to a male unit, and culminated in the formation of a unit consisting of one female and one male.
One successful and one attempted case of unification of units, and one case of change of a unit leader male are reported.
These changes occurred among eight resident units in a period of 7 months (196 female months). Though the types of social
changes were not much different from previous observations in Semien National Park, their frequencies seemed to be much higher.
The characteristics of Arsi gelada social changes are proposed to be related to the small size of the units. We also describe
a new confirmed case and one suspected case of infanticide, as well as one case of abortion at the time of male leader change. 相似文献
54.
The heart is assumed to have evolved as the organ for pumping blood. Here we report a pumping phenomenon in Hydra, a member of the phylum Cnidaria. We find that the peduncle, lower quarter of the body column, stores most of the gastrovascular fluid when the animal is an elongate form. Upon contraction of the polyp, the peduncle contracts and transfers the fluid into the rest of the cavity. We also find that Hydra RFamide III, a homolog of cardioexcitatory RFamide neuropeptides in higher organisms, elevates this transfer activity. Further, CnNk-2, a homolog of a cardiomuscular tissue marker Nkx-2.5, is expressed in the endodermal tissue of the peduncle. These observations indicate that the transfer of fluid by the peduncle has a similar neurological and genetic basis to the pumping of blood by the heart, suggesting that the Hydra peduncle and the heart of higher organisms share a common ancestral origin. 相似文献
55.
56.
Primary roots of radish (Raphanus sativus L.) seedlings were exposed to an inhomogeneous static magnetic field generated by a permanent magnet, during continuous rotation on a 0.06 rpm clinostat, thereby reducing the unilateral influence of gravity. The roots responded tropically to the static magnetic field with the tropism appearing to be negative. These roots responded significantly (P < 0.05) to the south pole of the magnet. The significant tropic response was found for a magnetic flux density of 13-68 mT, for a field gradient of 1.8-14.7 T/m, and for the product of magnetic field and field gradient of 0.023-1.0 T(2)/m. A small, but insignificant, response of the roots to the north pole has also been found. 相似文献
57.
Kawakami T Chiba T Suzuki T Iwai K Yamanaka K Minato N Suzuki H Shimbara N Hidaka Y Osaka F Omata M Tanaka K 《The EMBO journal》2001,20(15):4003-4012
NEDD8/Rub1 is a ubiquitin (Ub)-like post-translational modifier that is covalently linked to cullin (Cul)-family proteins in a manner analogous to ubiquitylation. NEDD8 is known to enhance the ubiquitylating activity of the SCF complex (composed of Skp1, Cul-1, ROC1 and F-box protein), but the mechanistic role is largely unknown. Using an in vitro reconstituted system, we report here that NEDD8 modification of Cul-1 enhances recruitment of Ub-conjugating enzyme Ubc4 (E2) to the SCF complex (E3). This recruitment requires thioester linkage of Ub to Ubc4. Our findings indicate that the NEDD8-modifying system accelerates the formation of the E2-E3 complex, which stimulates protein polyubiquitylation. 相似文献
58.
Coexistence of gland mucous cell-type mucin and lysozyme in gastric gland mucous cells 总被引:2,自引:1,他引:1
Hidaka E Ota H Katsuyama T Nakayama J Momose M Hidaka H Ishii K Murata F Tsuyama S Kurihara M Ishihara K Hotta K 《Histochemistry and cell biology》2000,113(2):91-98
Class III mucin, identified by paradoxical concanavalin A staining, is confined to gastric gland mucous cells and is an essential
component of the gastric surface mucous gel layer. The pretreatment required has hampered the application of this method to
electron microscopic studies. Antibody HIK1083 reacts selectively with class III mucins. The present study was undertaken
to explore, electron microscopically, the immunoreactivity of the human stomach to HIK1083. We examined normal mucosa from
resected human stomachs (five cases; formalin-fixed, paraffin-embedded) and gastric biopsy specimens from patients with early
gastric cancer [nine cases; glutaraldehyde- and osmium-fixed, epoxy-embedded (seven cases) and half-strength Karnovsky’s solution-fixed,
Lowicryl K4M-embedded (two cases)]. Immunostaining with HIK1083 and anti-lysozyme antibody was examined under light and electron
microscopes. Gland mucous cells were labeled with HIK1083, and lysozyme was detected in some gland mucous cells and surface
mucous cells. Electron microscopically, the secretory granules of gland mucous cells contained a single electron-dense core.
HIK1083-positive mucins and lysozyme coexisted in the secretory granules of gastric gland mucous cells. HIK1083-reactive mucins
and lysozyme were distributed in the matrix and in the dense core of these secretory granules, respectively. HIK1083 can be
used for electron immunohistochemistry.
Accepted: 1 December 1999 相似文献
59.
Molecular cloning of rat brain mitochondrial carrier protein-1 cDNA and its up-regulation during postnatal development 总被引:2,自引:0,他引:2
Kondou S Hidaka S Yoshimatsu H Tsuruta Y Itateyama E Sakata T 《Biochimica et biophysica acta》2000,1457(3):182-189
Brain mitochondrial carrier protein-1 (BMCP1), a new member of the mitochondrial uncoupling carrier, has been shown to be expressed predominantly in the brain of the mice and humans. We cloned rat BMCP1 cDNA and investigated its mRNA level during postnatal development and under various metabolic conditions. The nucleotide sequence of the cDNA revealed that rat BMCP1 protein was composed of 322 amino acid residues, and was 99 and 96% identical to the mouse and human proteins and 29, 33 and 35% identical to rat uncoupling protein (UCP) 1, UCP2 and UCP3, respectively. The molecular weight was predicted to be 36017 Da and the protein of this size was detectable when the cDNA was expressed in vitro. Using Northern blot analysis, the corresponding mRNA, approximately 1.8-kb in size, was found expressed predominantly in the cerebrum, cerebellum and hypothalamus. A unique developmental pattern was identified in the brain, where BMCP1 expression was low in their fetal life, but significantly elevated in the first postnatal week. Thereafter BMCP1 mRNA was maintained to be gradually increased. In 48-h fasted or insulin-induced hypoglycemic rats, BMCP1 mRNA expression in the hypothalamus slightly, but significantly, decreased compared with that in their appropriate controls. The present results indicate that BMCP1 may be involved in pathogenesis of mitochondrial dysfunction in neurons induced by aging or neurodegenerative disorders, and perhaps in energy balance in the brain. 相似文献
60.