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排序方式: 共有473条查询结果,搜索用时 15 毫秒
1.
Eugen van der Zypen 《Cell and tissue research》1974,151(2):201-218
Summary The interatrial septum of the rat heart contains cells which show a strong intensive-yellow paraformaldehyde-induced fluorescence. By electron microscopy these cells are characterized by an abundance of dense-core vesicles.Cholinergio axons form axo-somatic synaptic contacts with the catecholamine-containing cells. These cells, packed with dense-core vesicles, are frequently interdigitated and interconnected by zonulae and maculae adhaerentes and occludentes. The catecholamine-containing cells are surrounded by satellite cells either individually or in groups.The catecholamine-containing cells, which bear blunt, plumpish processes, can be subdivided, on the basis of position and morphology into two types. One class of cells lies within the fibroblast capsule of the intra-atrial ganglion (van der Zypen, Hasselhorst, Merz and Fillinger, 1974). A second aggregation of catecholamine-containing cells occurs outside the ganglia in close proximity to capillaries. The capillaries exhibit pores in the area of contact with the catecholaminergic cells. The structure of these catecholamine-containing cells is described and their possible function discussed.
Zusammenfassung Im Septum interatriale des Rattenherzens treten Zellen in Erscheinung, die nach Paraformaldehyd-Bedampfung eine intensive hellgelbliche Fluoreszenz zeigen. Diese Zellen zeichnen sich durch einen großen Reichtum an dense-core vesicles aus. Cholinerge Axone bilden axo-somatische Synapsen an den katecholaminhaltigen Zellen aus. Die mit dense-core vesicles angefüllten Zellen sind oft ineinander verzahnt und durch Zonulae adhaerentes verbunden. Einzeln oder in Gruppen werden die katecholamin-enthaltenden Zellen von Satelliten-Zellen umgeben.Die mit kurzen plumpen Fortsätzen versehenen katecholaminhaltigen Zellen lassen aufgrund ihrer Lage und eines andersartigen Baues zwei Typen erkennen. Eine Gruppe von Zellen liegt innerhalb der Fibrozytenkapsel des Ganglion intraatriale (van der Zypen, Hasselhorst, Merz und Fillinger, 1974). Eine zweite Ansammlung von Katecholamin enthaltenden Zellen findet sich außerhalb der Ganglien in engem Kontakt zu Kapillaren. Die Kapillaren weisen im Bereich des Kontaktes mit den katecholaminergen Zellen Poren auf. Die Struktur dieser Zellen wird geschildert und ihre mögliche Funktion diskutiert.相似文献
2.
Structure of internalin,a major invasion protein of Listeria monocytogenes,in complex with its human receptor E-cadherin 总被引:13,自引:0,他引:13
Schubert WD Urbanke C Ziehm T Beier V Machner MP Domann E Wehland J Chakraborty T Heinz DW 《Cell》2002,111(6):825-836
Listeria monocytogenes, a food-borne bacterial pathogen, enters mammalian cells by inducing its own phagocytosis. The listerial protein internalin (InlA) mediates bacterial adhesion and invasion of epithelial cells in the human intestine through specific interaction with its host cell receptor E-cadherin. We present the crystal structures of the functional domain of InlA alone and in a complex with the extracellular, N-terminal domain of human E-cadherin (hEC1). The leucine rich repeat (LRR) domain of InlA surrounds and specifically recognizes hEC1. Individual interactions were probed by mutagenesis and analytical ultracentrifugation. These include Pro16 of hEC1, a major determinant for human susceptibility to L. monocytogenes infection that is essential for intermolecular recognition. Our studies reveal the structural basis for host tro-pism of this bacterium and the molecular deception L. monocytogenes employs to exploit the E-cadherin system. 相似文献
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Deregulation of microRNAs by HIV-1 Vpr protein leads to the development of neurocognitive disorders.
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Eugen Karl Kempf 《Grana》2013,52(1):18-22
Ultra-thin sections of paratypes of the megaspore Horstisporites semireticulatus Jung from Liassic strata of Germany have been investigated by the transmission electron microscope. By this it could be demonstrated that the fossil sporoderm consists of two distinct layers. The inner layer (exine) is very thin (about 0.5 μ) and reveals a lamellated structure. The outer layer (perine) is thicker by far (about 25 μ or more) and is composed of ramifying sporonin threads, which form a three-dimensional network. Proximally, in the region of the triradiate dehiscence commissure, both layers coalesce. Distally the exine separates from the perine, forming a cavity hitherto, erroneously, called mesosporoid. The structural similarity of the Horstisporites semireticulatus sporoderm and that of such megaspores of Selaginella which show a monozonal kind of perine formation e.g. Selaginella selaginoides, favours the idea that the fossil species in question belongs to the Selaginellaceae 相似文献
6.
The Mesozoic megaspore Trileites pedinacron has been studied by transmission electron microscopy. The wall consists of one relatively thick layer (perine) which is perforated by radial tubes. This wall structure is compared with similar wall patterns of the zoosporangia of marine planctonic algae (Tasmanites, Pleurozonaria, Pachysphaera). Essential differences are pointed out. With T. pedinacron as type species a new form genus is established: Tasmanitriletes. 相似文献
7.
Judith Morales Suvi Ruuskanen Toni Laaksonen Tapio Eeva Rafael Mateo Eugen Belskii Elena V. Ivankina Antero Järvinen Anvar Kerimov Erkki Korpimäki Indrikis Krams Raivo Mänd Chiara Morosinotto Markku Orell Anna Qvarnström Heli Siitari Fred M. Slater Vallo Tilgar Marcel E. Visser Wolfgang Winkel Herwig Zang Juan Moreno 《Journal of avian biology》2013,44(2):111-120
The expression and impact of maternal effects may vary greatly between populations and environments. However, little is known about large‐scale geographical patterns of variation in maternal deposition to eggs. In birds, as in other oviparous animals, the outermost maternal component of an egg is the shell, which protects the embryo, provides essential mineral resources and allows its interaction with the environment in the form of gas exchange. In this study, we explored variation of eggshell traits (mass, thickness, pore density and pigmentation) across 15 pied flycatcher populations at a large geographic scale. We found significant between‐population variation in all eggshell traits, except in pore density, suggesting spatial variation in their adaptive benefits or in the females’ physiological limitations during egg laying. Between‐ population variation in shell structure was not due to geographic location (latitude and longitude) or habitat type. However, eggshells were thicker in populations that experienced higher ambient temperature during egg laying. This could be a result of maternal resource allocation to the shell being constrained under low temperatures or of an adaptation to reduce egg water loss under high temperatures. We also found that eggshell colour intensity was positively associated with biliverdin pigment concentration, shell thickness and pore density. To conclude, our findings reveal large‐ scale between‐population variation of eggshell traits, although we found little environmental dependency in their expression. Our findings call for further studies that explore other environmental factors (e.g. calcium availability and pollution levels) and social factors like sexual selection intensity that may account for differences in shell structure between populations. 相似文献
8.
Genome‐scale RNA interference screen identifies antizyme 1 (OAZ1) as a target for improvement of recombinant protein production in mammalian cells
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Laura Cristina Ceafalan Tudor Emanuel Fertig Teodora Cristina Gheorghe Mihail Eugen Hinescu Bogdan Ovidiu Popescu Jens Pahnke Mihaela Gherghiceanu 《Journal of cellular and molecular medicine》2019,23(2):819-827
The blood‐brain barrier (BBB) is essential for a functional neurovascular unit. Most studies focused on the cells forming the BBB, but very few studied the basement membrane (BM) of brain capillaries in ageing. We used transmission electron microscopy and electron tomography to investigate the BM of the BBB in ageing C57BL/6J mice. The thickness of the BM of the BBB from 24‐month‐old mice was double as compared with that of 6‐month‐old mice (107 nm vs 56 nm). The aged BBB showed lipid droplets gathering within the BM which further increased its thickness (up to 572 nm) and altered its structure. The lipids appeared to accumulate toward the glial side of the BM. Electron tomography showed that the lipid‐rich BM regions are located in small pockets formed by the end‐feet of astrocytes. These findings suggest an imbalance of the lipid metabolism and that may precede the structural alteration of the BM. These alterations may favour the accretion of abnormal proteins that lead to neurodegeneration in ageing. These findings warrant further investigation of the BM of brain capillaries and of adjoining cells as potential targets for future therapies. 相似文献