9-Methyl-7-bromoeudistomin D,a potent inducer of calcium release from sarcoplasmic reticulum of skeletal muscle

Summary The Ca²⁺-releasing action of several derivatives of eudistomin D isolated from a marine tunicate was compared with that of caffeine. It was found that 9-methyl-7-bromoeudistomin D was approximately 1000 times more potent than caffeine in causing Ca²⁺ release from the sarcoplasmic reticulum.The authors thank Ms A. Muroyama of this institute for her technical assistance and Prof. K. L. Rinehart of University of Illinois for his encouragement.     

The chemoarchitectonics in the forebrain of reptiles

Zusammenfassung Ausgehend vom Vorderhirn der Reptilien als schematischer Typus für Säugerverhältnisse, wurden histochemische Untersuchungen von Monoaminoxydase und Succinodehydrogenase im Vorderhirn der Schildkröten ausgeführt. Die Monoaminoxydasereaktion ist in den visceralen Abteilungen, dem limbischen System, Area preoptica und Hypothalamus stark, während die Succinodehydrogenasereaktion im Neostriatum, Paleostriatum und Nucleus rotundus des Thalamus dorsalis stärker zu sein scheint. Die Befunde lassen die Verteilungen der Enzymaktivität im kompliziert gebauten Vorderhirn der Säuger befriedigend erklären.     

Self-organizing optic-cup morphogenesis in three-dimensional culture

Balanced organogenesis requires the orchestration of multiple cellular interactions to create the collective cell behaviours that progressively shape developing tissues. It is currently unclear how individual, localized parts are able to coordinate with each other to develop a whole organ shape. Here we report the dynamic, autonomous formation of the optic cup (retinal primordium) structure from a three-dimensional culture of mouse embryonic stem cell aggregates. Embryonic-stem-cell-derived retinal epithelium spontaneously formed hemispherical epithelial vesicles that became patterned along their proximal-distal axis. Whereas the proximal portion differentiated into mechanically rigid pigment epithelium, the flexible distal portion progressively folded inward to form a shape reminiscent of the embryonic optic cup, exhibited interkinetic nuclear migration and generated stratified neural retinal tissue, as seen in vivo. We demonstrate that optic-cup morphogenesis in this simple cell culture depends on an intrinsic self-organizing program involving stepwise and domain-specific regulation of local epithelial properties.     

Periostin in vitreoretinal diseases

Proliferative vitreoretinal diseases such as diabetic retinopathy, proliferative vitreoretinopathy (PVR), and age-related macular degeneration are a leading cause of decreased vision and blindness in developed countries. In these diseases, retinal fibro(vascular) membrane (FVM) formation above and beneath the retina plays an important role. Gene expression profiling of human FVMs revealed significant upregulation of periostin. Subsequent analyses demonstrated increased periostin expression in the vitreous of patients with both proliferative diabetic retinopathy and PVR. Immunohistochemical analysis showed co-localization of periostin with α-SMA and M2 macrophage markers in FVMs. In vitro, periostin blockade inhibited migration and adhesion induced by PVR vitreous and transforming growth factor-β2 (TGF-β2). In vivo, a novel single-stranded RNAi agent targeting periostin showed the inhibitory effect on experimental retinal and choroidal FVM formation without affecting the viability of retinal cells. These results indicated that periostin is a pivotal molecule for FVM formation and a promising therapeutic target for these proliferative vitreoretinal diseases.     

氦浴温度对超流氦噪声沸腾压力振动的影响

噪声沸腾是超流氦传热中的一个特殊现象，对这种现象的充分认识有助于超流氦在诸如超导磁体的冷却等方面的实际应用．氦浴温度是影响噪声沸腾的一个重要因素．本文运用脉冲电流加热一个大小为２．５ｃｍ×２．５ｃｍ的小试样，同时用一个压力传感器测量了在不同氦浴温度下噪声沸腾时的压力振动，并对不同氦浴温度下噪声沸腾的压力振动曲线进行了详细的分析．实验结果显示在过冷态超流氦的沸腾中，一个极薄的气膜在小试样上振动，几乎没有什么噪声；而在饱和态超流氦的沸腾中，一个小试样大小相当的气泡在其表面上反复振动，并伴随着巨大的噪声和强烈的机械振动．氦浴温度对噪声沸腾的影响主要体现在对噪声沸腾的特征频率和沸腾状态发生改变时的临界静压液柱等方面．     

Symbioramide,a novel Ca2+-ATPase activator from the cultured dinoflagellateSymbiodinium sp.

Summary A novel sphingosine derivative, symbioramide, has been isolated from the laboratory-cultured dinoflagellateSymbiodinium sp. as a sarcoplasmic reticulum (SR) Ca²⁺-ATPase activator, and its structure elucidated to be1 on the basis of spectral and chemical means.Acknowledgments. We thank Ms M. Hamashima and Ms A. Muroyama for their technical assistance.