Opiate receptors in mice: genetic differences.

The concentration of opiate receptors in the brains of mice was determined by means of a naloxone-binding assay. The strains of mice used in these experiments were C57BL/6By, BALB/cBy, their reciprocal F₁ hybrids, and 7 recombinant-inbred strains derived by inbreeding from the F₂ generation. These strains could be divided into 3 groups on the basis of the number of opiate receptors: high (CXBH); low (CXBK); and intermediate (all the other strains). The difference in stereospecific binding of naloxone reflects a difference in the total number of receptor sites rather than in the affinity for the drug. The recombinantinbred strains also differ in their analgesic response to morphine, as previously determined by the tail-flick assay. The differences in the number of opiate receptors are not enough to account for the genetic difference in analgesic responsiveness. Both these parameters appear to be under different genetic control, and at least 2 genetic determinants may be involved in regulating the level of opiate receptors.     

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.     

Electroencephalographic changes with age in male mice.

Electroencephalographic (EEG) changes, as measured by the awake state, slow-wave sleep (SWS), rapid-eye movement (REM) patterns and ratio of REM/total sleep, were recorded in aging male mice of DBA/2J and C57BL/6J strains. Results indicate that there is a significant increase in the awake state accompanied by significant decrease in SWS with advancing age for both strains, although these changes appear more pronounced in DBA/2J mice than C57BL/6J mice. Of considerable significance is the finding that REM sleep is absent in mice of DBA/2J strain at 23.5 months of age. Based on these findings, the conclusion was reached that strain DBA/2J ages significantly faster than C57BL/6J. The difference in aging between the two strains emphasizes the need for additional studies dealing with genetic aspects of aging.     

Fluoride effects on leaf cell ultrastructure of olive trees growing in the vicinity of the Aluminium Factory of Greece

Summary Leaves of olive trees growing in the vicinity of the Aluminium Factory of Greece were ultrastructurally investigated in order to determine any malformations caused by environmental air pollutants, especially hydrogen fluoride, in comparison with control samples and normal seasonal senescence. Estimation of some elements accumulated by these leaves showed that they contained high amounts of F and Al attributable to the operation of the nearby factory. The most seriously effected cell components were found to be the mesophyll chloroplasts that show a dilation of the intrathylakoid space, increase of the number of plastoglobuli, discoloration of plastoglobuli, accumulation of large starch grains and an overall disorganized appearance of the organelle. The nuclear crystalloid inclusions have unusual shapes, while the vacuoles contain a fibrillar/granular material that increases their electron density. It is concluded that the ultrastructural malformations are caused by a combination of environmental stresses and air pollutants.This paper is dedicated to Professor Dr. Eberhard Schnepf on the occasion of his 60^th birthday.     

Effects of bisphenol A on the microtubule arrays in root meristematic cells of Pisum sativum L.

Bisphenol A (BPA), a widely used chemical in the plastics industry that displays weak oestrogenic properties, is an emerging environmental pollutant, potentially harmful to living organisms. The presumed cytotoxicity of BPA to plant cells has been poorly studied. To understand how BPA might influence plant cell division and affect the underlying cytoskeleton, the effects of BPA on the microtubule (MT) arrays of meristematic root-tip cells of Pisum sativum L. were investigated. Root tips of young seedlings were exposed to 20, 50 and 100 mg/L BPA for 1, 3, 6, 12 and 24 h. The effects of each treatment were determined by means of confocal laser scanning microscopy after immunolabelling of tubulin and counterstaining of DNA, and by use of light and transmission electron microscopy. It was found that BPA affected normal chromosome segregation, hampered the completion of cytokinesis and deranged interphase and mitotic MT arrays. BPA effects were dependent on the stage of each cell at the time of BPA entrance. Moreover, BPA induced the formation of macrotubules with a mean diameter of 32 ± 0.14 nm, compared with 23 ± 0.70 nm for the MT arrays in untreated cells. Finally, all MT arrays and macrotubules were depolymerised upon longer treatment. Taken together, the data suggest that BPA exerts acute anti-mitotic effects on meristematic root-tip cells of P. sativum, MT arrays constitute a primary sub-cellular target of BPA toxicity, and the manifested chromosomal abnormalities could be attributed to the disruption of the MT cytoskeleton.     

Estimating lagoonal biodiversity in Greece: comparison of rapid assessment techniques

An attempt is made to compare the results of different rapid biodiversity assessment techniques at the pan-Mediterranean, sectorial and local levels. A uniform multivariate pattern exists at the pan-Mediterranean and national (sectorial) levels: lagoons can be different when they host only a few species, but as species numbers increase, lagoons become homogenous in composition. Multivariate techniques cannot distinguish anthropogenically-impacted lagoons from those, which are naturally disturbed. In the pan-Mediterranean context it is the higher taxonomic levels, but in the national and local context it is the most abundant macrobenthic groups (polychaetes, molluscs and crustaceans) and meiobenthos which provide patterns closest to that derived from the species level. Taxonomic distinctness indices applied to polychaete and mollusc inventories provide meaningful results at most levels and scales of observation. These indices seem to be robust enough to discriminate anthropogenically impacted from naturally disturbed lagoons.     

The conduction of protons in different stereoisomers of dioxolane-linked gramicidin A channels

Two different stereoisomers of the dioxolane-linked gramicidin A (gA) channels were individually synthesized (the SS and RR dimers;. Science. 244:813-817). The structural differences between these dimers arise from different chiralities within the dioxolane linker. The SS dimer mimics the helicity and the inter- and intramolecular hydrogen bonding of the monomer-monomer association of gA's. In contrast, there is a significant disruption of the helicity and hydrogen bonding pattern of the ion channel in the RR dimer. Single ion channels formed by the SS and RR dimers in planar lipid bilayers have different proton transport properties. The lipid environment in which the different dimers are reconstituted also has significant effects on single-channel proton conductance (g(H)). g(H) in the SS dimer is about 2-4 times as large as in the RR. In phospholipid bilayers with 1 M [H(+)](bulk), the current-voltage (I-V) relationship of the SS dimer is sublinear. Under identical experimental conditions, the I-V plot of the RR dimer is supralinear (S-shaped). In glycerylmonooleate bilayers with 1 M [H(+)](bulk), both the SS and RR dimers have a supralinear I-V plot. Consistent with results previously published (. Biophys. J. 73:2489-2502), the SS dimer is stable in lipid bilayers and has fast closures. In contrast, the open state of the RR channel has closed states that can last a few seconds, and the channel eventually inactivates into a closed state in either phospholipid or glycerylmonooleate bilayers. It is concluded that the water dynamics inside the pore as related to proton wire transfer is significantly different in the RR and SS dimers. Different physical mechanisms that could account for this hypothesis are discussed. The gating of the synthetic gA dimers seems to depend on the conformation of the dioxolane link between gA's. The experimental results provide an important framework for a detailed investigation at the atomic level of proton conduction in different and relatively simple ion channel structures.