A comparison of the changes in the non‐neuronal cell populations of the superior cervical ganglia following decentralization and axotomy

Transecting the axons of neurons in the adult superior cervical ganglion (SCG; axotomy) results in the survival of most postganglionic neurons, the influx of circulating monocytes, proliferation of satellite cells, and changes in neuronal gene expression. In contrast, transecting the afferent input to the SCG (decentralization) results in nerve terminal degeneration and elicits a different pattern of gene expression. We examined the effects of decentralization on macrophages in the SCG and compared the results to those previously obtained after axotomy. Monoclonal antibodies were used to identify infiltrating (ED1+) and resident (ED2+) macrophages, as well as macrophages expressing MHC class II molecules (OX6+). Normal ganglia contained ED2+ cells and OX6+ cells, but few infiltrating macrophages. After decentralization, the number of infiltrating ED1+ cells increased in the SCG to a density about twofold greater than that previously seen after axotomy. Both the densities of ED2+ and OX6+ cells were essentially unchanged after decentralization, though a large increase in OX6+ cells occurred after axotomy. Proliferation among the ganglion's total non‐neuronal cell population was examined and found to increase about twofold after decentralization and about fourfold after axotomy. Double‐labeling experiments indicated that some of these proliferating cells were macrophages. After both surgical procedures, the percentage of proliferating ED2+ macrophages increased, while neither procedure altered the proliferation of ED1+ macrophages. Axotomy, though not decentralization, increased the proliferation of OX6+ cells. Future studies must address what role(s) infiltrating and/or resident macrophages play in regions of decentralized and axotomized neurons and, if both are involved, whether they play distinct roles. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 68–79, 2002     

Lack of homogeneity of receptive fields of visual neurons in the cortical area 18 of the cat

The receptive fields of complex neurons within area 18 of the cerebral cortex of the cat were determined by a computer-assisted method using a moving light bar substantially shorter than the long diameter of the receptive field as a visual stimulus. The visual cells repeatedly generated nerve impulses when the stimulus crossed well-defined active points within their receptive fields. Outside of these active points, the cells remained silent. It is suggested that the receptive fields are formed by a discontinuous accumulation of such active points. When the electrical activities of two neighbouring visual neurons are recorded simultaneously, their active points do not coincide. In addition, some active points were located outside the most prominent excitatory part of the receptive field of the studied cells. Individual visual cells typically differ in the number and distribution of active points. Since these cells best respond to a stimulus moving in a certain direction, it is suggested that they may act as direction of movement and/or velocity detectors. Alternate firing of a number of neighboring cells connected to a distributed pattern of peripheral receptors may form a system which is able to code for velocity and direction of the moving stimulus.     

Ultrastructural and cytochemical examination of the nuclear crystalloid inclusions of Olea europaea L. mesophyll cells

Summary The nuclei of mesophyll cells of olive trees contain numerous sizeable crystalloid inclusions. Cytochemical examination using epoxy resin-embedded, semithin-sectioned tissue indicated the presence of proteins and oligoor polysaccharides in these inclusions. Their electron microscopical analysis revealed a crystalline substructure consisting of intersected subunits of high order. The spacing of the lattice fibrils and the angles of intersection were determined and used to establish a model of the unit cell of crystallization. It is suggested that the nuclear crystalloids of olive trees consist of glycoprotein molecules. They differ from the intranuclear crystalloids observed in other species predominantly in the high density of their subunit arrangement.     

Mikrospektralphotometrische Untersuchungen zum Speichermechanismus des kationischen Farbstoffes Chrysoidin durch die lebende und tote Pflanzenzelle

Wie aus Elektrophorese- und spektralphotometrischen Untersuchungen hervorgeht, liegt der kationische Farbstoff Chrysoidin G, je nach dem pH-Wert der wäßrigen Farblösungen, als I-, II-, III- und IV-wertiges Kation und elektroneutrales Farbbasenmolekül vor. Von physiologischer Bedeutung ist nur das I-wertige Kation und das Farbbasenmolekül. Die Unabhängigkeit der Absorptionsmaxima wäßriger Farbstofflösungen mit konstantem pH-Wert von der Farbstoffkonzentration deutet darauf hin, daß Chrysoidin keine Assoziate bildet. In organischen Lösungsmitteln ergibt Chrysoidin G je nach dem Grad der Polarität des Solvens und dem pH-Wert der wäßrigen Phase bei Ausschüttelungs-versuchen unterschiedliche Absorptionskurven. Natriumnucleinat bedingt eine negative Metachromasie; die jeweilige Lage des Maximums wird von der Natriumnucleinatkonzentration bestimmt. Rutin übt keinen wahrnehmbaren Einfluß auf das Absorptionsspektrum aus. Nach einer Vitalfärbung von Oberepidermiszellen der Schuppenblätter von Allium cepa mit Chrysoidin G zeigen das diffus gefärbte Plasma und die darin auftretenden gelben Kugeln übereinstimmende Absorptionsspektren mit einem breiten Bandenmaximum bei ? 420 nm. Der lebende Zellkern färbt sich nicht. Der gefärbte volle Zellsaft der Unterepidermis besitzt ein Maximum bei ? 448 nm. Aus der Lage der Absorptionsmaxima und dem Verlauf der Absorptionskurven kann geschlossen werden, daß die Färbung des lebenden Plasmas auf eine Anreicherung des einwertigen Kations und des Farbbasenmoleküls in polaren Lipoiden beruht, während es sich bei der Färbung des fixierten Zellkerns um eine Bindung des Chrysoidins an Nucleinsäuren handelt. Die Vitalfärbung des vollen Zellsaftes mit Chrysoidin G ist nicht auf den Gehalt der Vakuolen an Flavonolen zurückzuführen, sondern hängt vermutlich vom pH-Wert des Zellsaftes ab.     

Ozone-induced microscopical changes and quantitative carbohydrate contents of hybrid poplar (Populus × euramericana)

Summary Cuttings of hybrid poplar (Populus × euramericana var. Dorskamp) were exposed to ozone (80 g/m³ from 2100 hours to 0700 hours, 180 g/m³ from 0700 hours to 2100 hours) for 3 months. Ozone reduced the starch content in leaves and stem bark, whereas starch granules accumulated in bundle sheath cells along small leaf veins. At the same time, sucrose and inositol content increased in the leaves. Mesophyll cells in the vicinity of the stomata were injured first, and droplet-like material appeared on their walls. In the sieve plates of fumigated trees, the pores showed a higher degree of narrowing than those of the control treatment. Cell collapse in the leaves was accompanied by water loss and an increase in air space. In the stems, the ozone treatment led to a reduced radial width, particularly in the xylem tissue. These results are discussed in relation to reduced or inhibited phloem loading and ozone-induced drought stress. The plants injured by ozone showed quite distinct patterns of metabolite responses as well as enzyme activities (PEP- and RubP-carboxylase) in the leaves from the top to the bottom. There were also remarkable differences in the reaction of sucrose and inositol between leaves and stem bark. Future research should therefore increasingly follow a whole-plant approach for a better understanding of complex plant reactions.     

Carbohydrate distribution and cellular injuries in acid rain and cold-treated spruce needles

Summary The cellular structures of acid rain-irrigated needles of several provenances of Norway spruce (Picea abies L. Karst) seedlings were studied after winter experimental freezing. Frost injuries and recovery were characterized by visual damage scoring and classification of mesophyll cell alterations, also using histochemical methods for carbohydrate fluorescent staining. The treatment with-30° C during the late dormancy period was sufficient to cause significant injuries and intracellular degradation in the tissues of the green needles. The most affected seedlings in terms of visual injury scoring were found among those treated with clean water or at pH 3, while freezing injury, defined as an occlusion of phenolic substances in the central vacuole of the mesophyll cells, was most abundant in the needles from spruces irrigated either with clean water or at pH 4 or pH 3. Electron microscopy revealed the details of the injury, e. g. thinning out of the cytoplasm and chloroplast stroma, darkening of the chloroplasts and eventually swelling of the chloroplasts and protoplast. PAS and ConA reactions in the needle tissue revealed intense starch accumulation in the mesophyll and transfusion tissues as early as in March, with a tendency to increase, especially in the untreated needles during the recovery period. Plasma membrane disturbances were indicated by histochemical identification of callose deposits in the mesophyll cell walls, these being most abundant in the acid rain-treated needles. All these findings suggest that freezing at –30° C was more deleterious to the seedlings pretreated with acid or clean water than to those not given additional irrigation.