Hydrocarbon-metabolizing activity of various mammalian cells in culture

Summary Two methods for determining the hydrocarbon-metabolizing enzyme activity of cultured mammalian cells were compared. The method designed to measure benzo[a]an-thracene-induced aryl hydrocarbon hydroxylase activity could detect and quantify enzyme activities in low passage rodent cells, but could not reproducibly detect levels in intermediate or high passage mouse, rat, or human cells. The method designed to measure the ability of a cell to convert benzo[a]pyrene from an organic-soluble to an aqueous acetone-soluble form proved to be more reproducible. This technique, when modified, was demonstrated to be an effective screening test for the detection of those lines with higher levels of hydrocarbon-metabolizing enzymes. Supported by the Council for Tobacco Research and Contract NIH 70-2068 within the Virus Cancer Program, National Cancer Institute, National Institutes of Health.     

Ontogeny of the proventitious epicormic buds in Quercus petraea.

In the present work, we described the fate of proventitious epicormic buds on the trunks of 40-year-old Quercus petraea trees and in parallel the vascular trace they produced in the wood. Our results show that small and large individual epicormic buds can survive as buds for 40 years and that both are composed of a terminal meristem and scales. Meristematic areas are detected in the scale axils of small buds; in addition to these meristems the large buds also have secondary bud primordia. The small buds are connected to the pith of the main stem by a unique trace, whereas the large buds are connected by one or multiple traces. A single trace might imply that the whole bud is still alive and multiple traces might indicate that the terminal meristem has died. In the latter case, each trace is connected to a secondary bud of the large bud. The buds found in a cluster are composed of a terminal meristem and scales with axillary meristems in the scale axils. A cluster is connected to the pith of a stem either by a unique trace when it seems to be the result of partial abscission of an epicormic shoot or multiple traces when it might have originated from an epicormic bud in which the terminal meristem has died. Whatever the type of the bud, the vascular trace in the bark is composed of a cambium, secondary xylem and parenchyma cells and the trace present in the wood had parenchyma cells with vestiges of secondary xylem. Each year, the vascular trace should be produced in the bark by the cambium of the tree but not by the bud itself. On 40-year-old Q. petraea, we observed a proliferation of epicormic buds and in parallel a multiplication of the number of vascular traces in the trunk, but the knots caused by the traces of epicormic buds in the wood, either as individuals or in clusters, are minor since their colours are only slightly darker than those of woody rays and they are less than 2 mm in diameter. The knots will appear when epicormic buds develop into shoots. Received: 30 March 1999 / Accepted: 09 June 1999     

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     

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.     

Protein kinase C activity and reactivity to phorbol ester in vascular smooth muscle from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY)

Protein kinase C (PKC) activity in aortic and renal arterial smooth muscle from SHR (20-23 wk male; mean arterial pressure = 178 mm Hg) and WKY (age/sex matched; mean arterial pressure = 126 mm Hg) was quantitated. Activity was greatest in the particulate fractions relative to the soluble fractions in all sources. The only difference between SHR and WKY was in the soluble fraction from SHR renal arteries, which had 2 fold more activity (255 pmol/mg/min) when compared with WKY (136 pmol/mg/min). This difference was not apparently related to force modulation, since the magnitude of isometric force development in renal arteries in response to phorbol 12,13-dibutyrate was not different between SHR and WKY. The magnitude of force developed in response to phorbol 12,13-dibutyrate and PKC activity in the particulate fraction was greatest in aorta vs. renal arteries in both WKY and SHR. These results suggest that regional vascular differences in the amount of PKC activity may exist which are not apparently related to a disease state (i.e., hypertension). These differences may be related to differential sensitivity to phorbol ester-mediated contractions in isolated smooth muscle.     

Isolation of mouse N-CAM-related cDNA: detection and cloning using monoclonal antibodies.

Clones coding for the mouse neural cell adhesion molecule (N-CAM) were isolated from a cDNA library prepared in the expression vector lambda gt 11 from mRNA extracted from a mouse neuroblastoma cell line. This library was screened with two anti-N-CAM monoclonal antibodies directed against different sites on the molecule and with rabbit anti-N-CAM serum. Two clones were identified with the first monoclonal antibody, three with the second one, none reacted with both. The relevance of these cDNA clones to N-CAM was confirmed by several observations. First, cDNA sequences detected with one monoclonal antibody cross-hybridized with those identified by the other antibody. Second, the different fusion proteins all bound the rabbit serum in addition to one monoclonal antibody. Finally, the probes hybridized to discrete mRNA species of sufficient lengths to code for the very large N-CAM polypeptides in RNA preparations from N-CAM-expressing, but not from N-CAM-negative cells. An additional mRNA species not seen in embryonic brain was expressed in adult mouse brain. Genomic blot experiments indicated that sequences corresponding to one of our probes are present only a few times in the mouse genome.     

In vivo fluorescence excitation and absorption spectra of marine phytoplankton: I. Taxonomic characteristics and responses to photoadaptation

Absorption and fluorescence excitation spectra were measuredfor batch cultures of five species of marine phytoplankton grownunder high and low light. These spectra were examined for propertiescharacteristic of taxonomic position and of photoadaptive response.While regions of absorption and excitation of chlorophyll afluorescence diagnostic of pigment composition were identifiable,photoadaptive response had greater influence on spectral variability.Although reduced growth irradiance caused changes in both theabsorption and fluorescence excitation spectra, the fluorescenceexcitation spectrum appears to be more sensitive to alterationsin the ambient light field for growth than does the absorptionspectrum. For a single species. the fluorescence excitationspectrum for a sample grown at low irradiance showed greaterstructure than that for the sample grown at a high irradiance.Under low light conditions, the excitation of chlorophyll afluorescence by accessory pigments increased relative to theexcitation by chlorophyll a itself The highest fluorescenceyields occur in the blue-green region of the spectrum, correspondingto bands of peak absorption by the accessory pigments. Changesin absorption spectra are less marked, but two features recur.First. in the blue-green region of the spectrum from -500–560nm. absorption is enhanced in the low-light cells relative tothat of the high-light cells. Second, the ratio of absorptionat 435 nm to that at 676 nm was greater for the high-light cells.Correlating changes in pigment concentrations were observed.The influence of photoadaptation on the properties of fluorescenceexcitation spectra is as great or greater than the influenceof pigment complements characteristic of specific algal taxa.