肝细胞生长因子mRNA在成年小鼠和人胎儿不同器官中的表达

本实验从成年小鼠和胎龄４－５月的人胎儿不同器官中分离总ＲＮＡ。经斑点印迹分析显示,肝细胞生长因子（ＨＧＦ）ｍＲＮＡ在成年ＫＭ小鼠多种器官中表达,其表达水平由高到低依次为：肺、肝、肾、卵巢、睾丸、大脑和胃;在脾、心、骨髓、小肠和骨骼肌组织中以ＨＧＦｍＲＮＡ。在胎龄４－５月的人胎儿中,ＨＧＦｍＲＮＡ表达水平由高到低依次为：大脑、肝、腮腺、胃、小肠、肾、心和骨骼肌;肺和脾组织为阴性。由此可见,ＨＧＦ在成     

On disturbance of homeostasis in organ-cultured tissue

Summary The intact membranous rat mesentery was cultured in Eagle's minimum essential medium containing no serum or only low concentrations of serum. The procedure is in some important respects superior to previous organ culture techniques. To estimate the extent of disturbance of homeostasis of the tissue in culture, the spontaneous mast-cell histamine release was quantitated after preculture preparation of the specimens and after different intervals in culture. Also, the proliferation of fibroblasts and mesothelial cells that predominate in the mesentery was assessed at 48 h by cytofluorometric quantitation of DNA in single-tissue cells. Spontaneous histamine release was time dependent during cultivation, amounting to ca. 50% at 48 h, and was affected by the medium used for moistening the tissue before cultivation. Culturing also brought about great spontaneous increase in the proliferation of fibroblasts and mesothelial cells, the rate being related to the concentration of serum. Addition of the mast-cell secretagogues 48/80 or polymyxin B at 1 h caused rapid release of 50 to 60% of the histamine and was followed by augmented proliferation in the serum-containing media. The spontaneous increase of cell proliferation in tissue culture may be causally related to mast-cell secretion. Further studies are needed to define factors influencing the spontaneous mast-cell secretion and the mast-cell-dependent mitogenesis in normal tissue cells Supported by grants from the Swedish Medical Research Council (Project 5942) and State Board for Animal Experiments.     

Pattern of synaptic connections in the pineal organ of the ayu,Plecoglossus altivelis (Teleostei)

Summary Synaptic connections were studied by means of electron microscopy in the sensory pineal organ of the ayu, Plecoglossus altivelis, a highly photosensitive teleost species. Three types of specific contacts were observed in the pineal end-vesicle: 1) symmetrically organized gap junctions between the basal processes of adjacent photoreceptor cells; 2) sensory synapses endowed with synaptic ribbons, formed by basal processes of photoreceptor cells and dendrites of pineal neurons; 3) conventional synapses between pineal neurons, containing both clear and dense-core vesicles at the presynaptic site. Based on these findings, the following interpretations are given: (i) The gap junctions may be involved in an enhancement of electric communication and signal encoding between pineal photoreceptor cells. (ii) The sensory synapses transmit photic signals from the photoreceptor cells to pineal nerve cells. (iii) The conventional synapses are assumed to be involved in a lateral interaction and/or summation of information in the sensory pineal organ. A concept of synaptic relationships among the sensory and neuronal elements in the pineal organ of the ayu is presented.Fellow of the Alexander von Humboldt Foundation, Federal Republic of Germany     

Preparation and discharge of secretion in the subcommissural organ of the rat

Summary The secretion of the subcommissural organ (SCO) of the rat was studied by means of immunocytochemistry at the electron-microscopic level with the use of (1) the polar embedding medium Lowicryl K4M at -30° C, (2) the protein A-gold technique, and (3) a rabbit antiserum against bovine Reissner's fiber (see Sterba et al. 1981).Two different substructures of the ependymal and the hypendymal SCO-cells display a positive immunocytochemical reaction: (1) sacs containing flocculent secretion, which originate from the granular endoplasmic reticulum, and (2) vacuoles filled with fine granular secretion, which are pinched off from the Golgi apparatus. The secretory material of the sacs and the vacuoles is discharged both (i) apically into the cerebrospinal fluid and (ii) basally into intercellular spaces of the SCO-hypendyma. The apically released secretion is condensed to a lamina-like formation, which more caudally assumes the form of Reissner's fiber. The route of the basally released secretion remains, however, vague. The periodically striated bodies, which were thought to be morphological mediators of the discharge of the secretion into the capillaries, are never labeled by gold particles.Supported by grants from the Ministry for Science and Technology of the German Democratic RepublicThe expert technical assistance of Mrs. B. Wolff, Mrs. S. Mehnert, Mrs. E. Siebert, Mrs. Ch. Schneider, and Mrs. I. Seifert is gratefully acknowledged     

Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review

A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed.     

The adaptation of a two-compartment cell renewal system to external demands

Summary The inner enamel epithelium (IEE) covers the labial tooth aspect as a one cell layer which, when cut sagittally, appears as a longitudinal cell column extending from the tooth origin toward the periphery. Following sudden tooth shortening, the IEE responds by an increased cell production which later declines below normal values. The perturbation affects all cell kinetic parameters; the progenitor compartment, which initially increases, diminishes in size toward end of the experiment. The cell cycle transition times, which initially decline, rise toward the end of the experiment. The mean normal daily cell production rate of 70 cell % (i.e. 70 cells are produced by 100 progenitors) increases to 111 cell % and then declines to a low of 51 cell %. The IEE response typifies the behavior of other cell renewal systems such as intestinal epithelium and epidermis.     

Fine structure of the pineal organ in the troglobytic fish,Typhlichthyes subterraneous (Pisces: Amblyopsidae)

Summary The pineal organ of the blind, cave-dwelling fish, Typhlichthyes subterraneous, was examined with both light and electron microscopes. Like the eyes, the pineal in this troglobytic species was found to be regressed. Two cell types, photoreceptor and supportive cells, were described in the pineal epithelium. Although ganglion cells were not identified, small, unmyelinated nerve fibers were present. The photoreceptor cells had degenerated outer segments. Accordingly, it was suggested that the pineal in this species is not likely to function in photoreception. However, the presence of well developed Golgi bodies, clear and dense-cored vesicles, variable amounts of rough endoplasmic reticulum and glycogen particles indicated that both cell types are metabolically active and may play a role in secretion.     

Scanning and transmission electron microscopy of the subfornical organ of the grass frog (Rana pipiens)

Summary The ventricular surface of the subfornical organ of the frog is made up of ependymal cells with numerous apical microvilli, occasional cytoplasmic protrusions and many vacuoles projecting into the lumen of the third ventricle. Between these cells dendrites of cerebrospinal fluid-contacting neurons reach the ventricle to terminate in bulbous enlargements. In addition, flask-shaped encephalo-chromaffin cells, containing granulated vesicles and aggregates of filaments in their cytoplasm, project into the cerebrospinal fluid. Surrounding the centrally located capillaries are enlarged dendrites and axons of heterogeneous morphology, some of which appear to originate within the subfornical organ, intermingled with dendrites and axons of normal structure. The glial cells in this region, especially the microglial cells, often contain large lipofuscin inclusions, suggestive of degeneration and subsequent phagocytosis of some of the enlarged dendrites and axons. The normally scarce neurosecretory peptidergic axons become more evident and form typical Herring bodies in stalk-transected animals. Neuronal perikarya of varying morphology are predominantly located peripheral to the region of enlarged dendrites and axons. Supraependymal macrophages are particularly numerous on the subfornical organ.Abbreviations used CSF cerebrospinal fluid - SEM scanning electron microscope, scanning electron microscopy - SFO subfornical organ - TEM transmission electron microscope, transmission electron microscopy Supported, in part, by NIH grant NB 07492The skillful technical assistance of J.G. Linner and the secretarial assistance of Ann Gerdom are gratefully acknowledged. The SEM studies were made possible through a grant from the Graduate College of Iowa State University and the use of the SEM facility in the Department of Botany     

Structural re-evaluation of the neurosecretory system in the crayfish eyestalk

Summary The topography of the neurosecretory system in the decapod eyestalk has not been precisely delineated with light microscopy. Cobalt iontophoresis and electron microscopy have proved useful in clarifying the microstructure of this system. The sinus gland (sg) of the crayfish eyestalk consists of aggregated axon terminals which end at or near the blood space, lontophoresing cobalt back through the cut base of the sinus glands reveals proximal cell bodies in the eyestalk only in the X organ (Xo) region. Electron microscopy demonstrates that axons from about 115 neurosecretory cell bodies in the Xo form the Xo-sg tract. Intermingled with these Xo somata are smaller non-neurosecretory cell bodies which do not send axons into the sinus gland. One of these exhibits catecholamine fluorescence. Backfilling also reveals a second group of fibres which run from the brain along the optic tract and into the sinus gland. These brain-sg fibres are smaller in diameter than Xo-sg axons and lack neurosecretory vesicles. From these fibres collaterals extend into the eyestalk neuropil, especially in the proximity of the visual elements. The possible function of these non-neurosecretory processes within the sinus gland is discussed.This work was supported by a National Research Council of Canada grant     

A continuous-flow method of organ culture

Summary A method of perfusion organ culture is described in which explants cultured at the airmedium interface are bathed by a continuous flow of nutrient medium. Morphological studies on the fetal rat lung indicate that explant development in this system is comparable to that obtained using standard organ-culture dishes. Medium supply is easily manipulated and continuous sampling of the effluent stream is possible without disturbing the immediate explant environment. The basic design facilitates secretory-response studies on cultured organ explants as demonstrated by a study of glucose-stimulated insulin release by the neonatal rat pancreas. This work was supported by U. S. Public Health Service Training Grant No. GM 00114.