Immunocytochemistry of brain-reactive monoclonal antibodies in peripheral tissues

Among a total of 135 tissue-reactive monoclonal antibodies previously prepared, 81 were brain-selective and were classified into neuronal and non-neuronal categories. The neuronal antibodies were again subdivided into antineurofibrillar, antiperikaryonal-neurofibrillar, and antisynapse-associated groups. On the basis of morphologic, developmental, biochemical, and pathologic criteria, the antibodies in at least two of these groups were found to detect heterogeneous antigens (called "neurotypes") rather than different antigenic determinants in single antigens. On examining the distribution in peripheral organs of staining patterns of 11 antineuronal brain-reactive antibodies, we now confirm that these antibodies are, indeed, largely brain-specific. In general, non-neuronal elements in liver, lung, heart, thymus, intestine, adrenal, and spleen remained unstained. However, most of the antibodies stained peripheral neural elements. Occasional antibodies did stain selected, non-neuronal structures. Four out of five antineurofibrillar antibodies stained nerve fibers in adrenal medulla, intestine and thymus. All of three antiperikaryonal-neurofibrillar antibodies also stained nerve fibers in the adrenal medulla, but not in other organs. Two out of three antisynapse-associated antibodies stained what appear to be nerve contacts on adrenal medullary cells, but not on any other peripheral cells examined. The non-neuronal peripheral staining patterns were restricted to selective nuclear staining exhibited by two out of five antineurofibrillar antibodies and the staining of macrophage and selected cardiac muscle nuclei by two of three antisynapse-associated antibodies. However, one antineurofibrillar antibody also stained the cytoplasm of selected liver cells. Among non-neuronally reacting antibodies, two antibodies stained nuclei of all cells except neurons in brain as well as peripheral organs. An antibody staining the ciliary epithelium of choroid plexus also stained basal bodies of ciliated bronchial epithelium. The overall data suggest that the specificity of brain-reactive antibodies is high and that their cross-reactivity with epitopes in non-nervous tissue is rare. In these cases, the antibodies seem to provide specific reagents for these additional structures as well as for their specific brain antigens.     

Some observations on coleoptile cell ultrastructure in ungerminated grains of rice (Oryza sativa L)

Summary The ultrastructure of coleoptile cells of ungerminated rice grains has been examined following fixation in glutaraldehyde and osmium tetroxide. In many respects the cell structure resembles that reported for other dormant seed tissues: the cells contain protein bodies and lipid droplets, mitochondria and plastids show little internal structure but cytoplasm invaginates into many plastids; golgi cisternae cannot be discerned. Rough ER is present as cisternae surrounding protein bodies, as occasional regions of parallel layers, and in concentric whorls where it alternates with smooth paired membranes of an unknown nature. The ribosomes on the ER are at least partly arranged into regular rows. Various crystalline, presumably proteinaceous, inclusions lie in the groundplasm, plastids and nuclei.     

“Unblocking” Serum Activity <Emphasis Type="Italic">in vitro</Emphasis> in the Polyoma System may Correlate with Antitumour Effects of Antiserum <Emphasis Type="Italic">in vivo</Emphasis>

In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual^1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro^2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development^5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera⁹. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo^10,11, which has been tentatively attributed to its unblocking activity^8,9 or, possibly, to a complement-dependent cytotoxicity¹⁰. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity^9,10.     

Association of Viral Reverse Transcriptase with an Enzyme degrading the RNA Moiety of RNA-DNA Hybrids

DURING replication of RNA tumour viruses, the genetic information contained in the viral RNA seems to be transferred to DNA^1,2. Studies on the enzymatic activities present in the virus particles suggest that this transfer is mediated by an RNA dependent DNA polymerase^3,4. RNA-DNA hybrids have been demonstrated to occur as intermediates in this reaction⁵ and single stranded DNA is generated as an early reaction product⁶, which is then replicated to give a double stranded DNA product^6–8. The mechanism by which the single stranded DNA is displaced from the RNA template is, however, not known.     

Reconstitution of a GTPase Activity a 50S Ribosomal Protein from <Emphasis Type="Italic">E. coli</Emphasis>

DURING each step of peptide chain elongation the ribosome shifts up one triplet along the messenger RNA with concomitant movement of the peptidyl-transfer RNA from the donor to the acceptor site. This process, commonly known as translocation, is triggered by a supernatant protein, factor G, which in association with the ribosome cleaves GTP into GDP and inorganic phosphate^1,2 and it has been argued that the energy liberated in this reaction is used “to carry the complex one triplet forward”³.     

Uraninschwellen des Protoplasmas der BraunalgeStypocaulon scoparium

Ohne Zusammenfassung     

Microradiographic determination of lead in mineralized tissues

Summary A dichromatic contact microradiographic method is presented for quantitative microanalysis of lead in mineralized tissues utilizing the L absorption edges of lead. Sections of mineralized tissue with a thickness of about 100 are exposed to filtered molybdenum K and copper K radiation. Quantitative localization of lead is possible within small areas of the order of 50 ² with an accuracy of 25 · 10^–12g lead. The method has been applied to studies of long term accumulation of lead in bone tissue.     

Expression of the Ganglioside GD3 in Human Meningiomas Is Associated with Monosomy of Chromosome 22

The ganglioside composition of 59 meningiomas has been compared with a molecular genetic analysis of chromosome 22 in the same specimens. Major gangliosides were GM3 (II3NeuAc-LacCer) and/or GD3 [II3(NeuAc)2-LacCer]. In specimens with no or partial deletions of chromosome 22, the GM3 ganglioside predominated, and the mean value for GM3, 61% of total sialic acid, was around four times higher than that for GD3. A loss of chromosome 22, found in 56% of the specimens, was shown to be associated with an increase in the proportion of ganglioside GD3, with the ratio between mean values of GM3 and GD3 being approximately 1:1. Logistic regression revealed that the probability of predicting monosomy of chromosome 22 by the GD3 proportion was 66%.     

Estimation of the effect of photoinhibition on the carbon gain in leaves of a willow canopy

The occurrence of photoinhibition of photosynthesis in leaves of a willow canopy was examined by measuring the chlorophyll-a fluorescence ratio of F _V/F _M (F_M is the maximum fluorescence level of the induction curve, and F_V is the variable fluorescence, F _V=F _M–F ₀, where F₀ is the minimal fluorescence). The majority of the leaves situated on the upper parts of peripheral shoots showed an afternoon inhibition of this ratio on clear days. This was the consequence of both a decrease in F _M and a rise in F _O. In the same leaves the diurnal variation in intercepted photosynthetic photon flux density (PPFD) was monitored using leaf-mounted sensors. Using the multivariate method, partial least squares in latent variables, it is shown that the dose of PPFD, integrated and linearly weighted over the last 6-h period, best predicts photoinhibition. Photoinhibition occurred even among leaves that did not intercept PPFDs above 1000 mol·m^–2·s^–1. Exposure of leaves to a standard photoinhibitory treatment demonstrated that the depression in the F _V/F _M ratio was paralleled by an equal depression in the maximal quantum yield of CO₂ uptake and a nearly equal depression in the rate of bending (convexity) of the light-response curve of CO₂ uptake. As a result, the rate of net photosynthesis is depressed over the whole natural range of PPFD. By simulating the daily course in the rate of net photosynthesis, it is estimated that in the order of one-tenth of the potential carbon gain of peripheral willow shoots is lost on clear days as a result of photoinhibition. This applies to conditions of optimal temperatures. Photoinhibition is even more pronounced at air temperatures below 23° C, as judged from measurements of the F_V/F_M ratio on clear days: the afternoon inhibition of this ratio increased in a curvilinear manner from 15% to 25% with a temperature decrease from 23° to 14° C.Abbreviations and Symbols F_O minimum fluorescence - F_V variable fluorescence - F_M maximum fluorescence - PLS partial least squares in latent variables - PPFD photosynthetic photon flux density - VPD water vapour-pressure deficit This study was supported by the Swedish Natural Science Research Council. We are indebted to Dr. Jerry Leverenz (Department of Plant Physiology, University of Umeå, Sweden) for guidance with the modelling of the photosynthesis data.     

Current perceptions of Photosystem II

In the last few years our knowledge of the structure and function of Photosystem II in oxygen-evolving organisms has increased significantly. The biochemical isolation and characterization of essential protein components and the comparative analysis from purple photosynthetic bacteria (Deisenhofer, Epp, Miki, Huber and Michel (1984) J Mol Biol 180: 385–398) have led to a more concise picture of Photosystem II organization. Thus, it is now generally accepted that the so-called D1 and D2 intrinsic proteins bind the primary reactants and the reducing-side components. Simultaneously, the nature and reaction kinetics of the major electron transfer components have been further clarified. For example, the radicals giving rise to the different forms of EPR Signal II have recently been assigned to oxidized tyrosine residues on the D1 and D2 proteins, while the so-called Q₄₀₀ component has been assigned to the ferric form of the acceptor-side iron. The primary charge-separation has been meaured to take place in about 3 ps. However, despite all recent major efforts, the location of the manganese ions and the water-oxidation mechanism still remain largely unknown. Other topics which lately have received much attention include the organization of Photosystem II in the thylakoid membrane and the role of lipids and ionic cofactors like bicarbonate, calcium and chloride. This article attempts to give an overall update in this rapidly expanding field.