Regulation of spontaneous rhythmic activity and organization of pacemakers as memory traces by spike-timing-dependent synaptic plasticity in a hippocampal model

It is widely believed that memory traces can be stored through synaptic conductance modification of dense excitatory recurrent connections (ERCs) in the hippocampal CA3 region, namely associative memory. ERCs, on the other hand, are crucial to maintain spontaneous rhythmic activity in CA3. Since it is experimentally suggested that synaptic conductances of ERCs are modified through spike-timing-dependent synaptic plasticity (STDP), rhythmic activity might modify ERCs with the presence of STDP because rhythmic activity involves discharges of pyramidal cells. Memory patterns that are stored using ERCs might thus be modified or even destroyed. Rhythmic activity itself might also be modified. In this study, we assumed that the synaptic modification in the hippocampal CA3 was subject to STDP, and examined the coexistence of memory traces and rhythmic activity. The activity of the network was dominated by radially propagating burst activities (radial activities) that initiated at local regions and acted as pacemakers. The frequency of the rhythmic activity converged into one specific frequency with time, depending on the shape of the STDP functions. This indicates that rhythmic activity could be regulated by STDP. By applying theta burst stimulation locally to the network, we found that the stimulation whose frequency was higher than that of the spontaneous rhythmic activity could organize a new radial activity at the stimulus site. Newly organized radial activities were preserved for seconds after the termination of the stimulation. These results imply that CA3 with STDP has an ability to self-regulate rhythmic activity and that memory traces can coexist with the rhythmic activity by means of radial activity

AXIS FOR ROTATION AT THE INTERVERTEBRAL JOINT IN JAPANESE MONKEYS

The position of axis for rotation at the intervertebral joint was investigated using ten Japanese monkeys. The position of axis for rotation at the intervertebral joint was shifted from dorsal to ventral direction on the superior and inferior views of the 1st thoracic vertebra and was next shifted from ventral to dorsal direction on the superior and inferior views of the 10th thoracic vertebra, with some exceptions. X-ray examination demonstrated that in the Japanese monkeys, lordosis was seen in both the cervical and lower lumbar(L5-L7) spine, whereas kyphosis was seen in the thoracic and upper lumbar (L1-L4) spine. Therefore, the possibility that the position of axis for rotation at the intervertebral joint was related to the curvature of the spinal column was not supported by the present study

AXIS FOR ROTATION AT THE INTERVERTEBRAL JOINT IN JAPANESE MONKEYS

The position of axis for rotation at the intervertebral joint was investigated using ten Japanese monkeys. The position of axis for rotation at the intervertebral joint was shifted from dorsal to ventral direction on the superior and inferior views of the 1st thoracic vertebra and was next shifted from ventral to dorsal direction on the superior and inferior views of the 10th thoracic vertebra, with some exceptions. X-ray examination demonstrated that in the Japanese monkeys, lordosis was seen in both the cervical and lower lumbar(L5-L7) spine, whereas kyphosis was seen in the thoracic and upper lumbar (L1-L4) spine. Therefore, the possibility that the position of axis for rotation at the intervertebral joint was related to the curvature of the spinal column was not supported by the present study

Ablation of the scaffold protein JLP causes reduced fertility in male mice

金沢大学がん研究所がん分子細胞制御The specific and efficient activation of mitogen-activated protein kinase (MAPK) signaling modules is mediated, at least in part, by scaffold proteins. c-Jun NH2-terminal kinase (JNK)-associated leucine zipper protein (JLP) was identified as a scaffold protein for JNK and p38 MAPK signaling modules. JLP is expressed nearly ubiquitously and is involved in intracellular signaling pathways, such as the Gα13 and Cdo-mediated pathway, in vitro. To date, however, JLP expression has not been analyzed in detail, nor are its physiological functions well understood. Here we investigated the expression of JLP in the mouse testis during development. Of the tissues examined, JLP was strongest in the testis, with the most intense staining in the elongated spermatids. Since the anti-JLP antibody used in this study can recognize both JLP and sperm-associated antigen 9 (SPAG9), a splice variant of JLP that has been studied extensively in primates, we also examined its expression in macaque testis samples. Our results indicated that in mouse and primate testis, the isoform expressed at the highest level was JLP, not SPAG9. We also investigated the function of JLP by disrupting the Jlp gene in mice, and found that the male homozygotes were subfertile. Taken together, these observations may suggest that JLP plays an important role in testis during development, especially in the production of functionally normal spermatozoa. © 2008 Springer Science+Business Media B.V

サル ノウ アリルアミダーゼ : セイシツ ト セイリ カッセイ ペプチド ブンカイ キサ ニ カンスル ケンキュウ

京都大学0048新制・論文博士理学博士乙第3686号論理博第626号新制||理||292(附属図書館)UT51-53-M115(主査)教授 高橋 健治, 教授 大沢 済, 教授 日高 敏隆学位規則第5条第2項該当Kyoto UniversityDFA