Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character最新文献

{"title":"Alpha-(2----8)-polysialic acid immunoreactivity in voltage-sensitive sodium channel of eel electric organ.","authors":"W M James,&nbsp;W S Agnew","doi":"10.1098/rspb.1989.0046","DOIUrl":"https://doi.org/10.1098/rspb.1989.0046","url":null,"abstract":"<p><p>The voltage-sensitive sodium channel from eel electroplax is formed of a polypeptide of 208,321 Da, to which is attached ca. 85 kDa of carbohydrate. Sialic acid is a prominent constituent, contributing ca. 113 negative charges to the protein surface. We here demonstrate that antibodies raised against the bacterial antigen alpha-(2----8)-polysialic acid, specific for polymers of ten or more consecutive sialic acid residues, react specifically and with high affinity to the electroplax sodium channel. In extracts of electroplax membranes, the sodium channel is the only protein that demonstrates this immunoreactivity, suggesting the presence of a polysialosyl-sialyltransferase specifically committed to this unique post-translational modification of the sodium channel. Polysialic acid is rare in vertebrates, having previously been found only associated with neural-cell adhesion molecules, present in the developing neuromuscular system. The other prominent source is the capsular polysaccharide of highly pathogenic meningitis bacteria. Antibodies to the bacterial antigen thus provide highly specific affinity markers for the sodium channel. The high avidity of these antibodies and the ratio of sialic acid residues to consensus glycosylation sites suggest that the terminal chains are well over ten sialosyl residues in length, potentially extending 10-30 nm into the extracellular environment.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1287","pages":"233-45"},"PeriodicalIF":0.0,"publicationDate":"1989-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0046","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13621907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Properties of acetylcholine-receptor activation in human Duchenne muscular dystrophy myotubes.","authors":"E Mancinelli,&nbsp;A Sardini,&nbsp;A D'Aumiller,&nbsp;G Meola,&nbsp;G Martucci,&nbsp;G Cossu,&nbsp;E Wanke","doi":"10.1098/rspb.1989.0047","DOIUrl":"https://doi.org/10.1098/rspb.1989.0047","url":null,"abstract":"<p><p>In human myotubes cultured from biopsies of normal subjects and dystrophic patients we investigated, with the patch-clamp technique, the activation properties of the nicotinic acetylcholine receptor (AChoR) in the presence of acetylcholine and suberyldicholine. The single-channel conductance and the lifetime of the openings were not found to differ. In contrast, the average frequency of openings was about four times higher in Duchenne muscular dystrophy (DMD) myotubes in the presence of equal amounts of acetylcholine, but not of suberyldicholine. The most reasonable conclusion from this observation is that the behaviour of the AChoR is not altered in DMD cells but that there is a greater average concentration of ACho molecules present around AChoRs. This leads to the tentative conclusion that the activity of the enzyme acetylcholinesterase (AChoE) is impaired by some unknown mechanism in the dystrophic myotube.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1287","pages":"247-57"},"PeriodicalIF":0.0,"publicationDate":"1989-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0047","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13621908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Propulsion of a fin whale (Balaenoptera physalus): why the fin whale is a fast swimmer.","authors":"N Bose,&nbsp;J Lien","doi":"10.1098/rspb.1989.0043","DOIUrl":"https://doi.org/10.1098/rspb.1989.0043","url":null,"abstract":"<p><p>Measurements of an immature fin whale (Balaenoptera physalus), which died as a result of entrapment in fishing gear near Frenchmans Cove, Newfoundland (47 degrees 9' N, 55 degrees 25' W), were made to obtain estimates of volume and surface area of the animal. Detailed measurements of the flukes, both planform and sections, were also obtained. A strip theory was developed to calculate the hydrodynamic performance of the whale's flukes as an oscillating propeller. This method is based on linear, two-dimensional, small-amplitude, unsteady hydrofoil theory with correction factors used to account for the effects of finite span and finite amplitude motion. These correction factors were developed from theoretical results of large-amplitude heaving motion and unsteady lifting-surface theory. A model that makes an estimate of the effects of viscous flow on propeller performance was superimposed on the potential-flow results. This model estimates the drag of the hydrofoil sections by assuming that the drag is similar to that of a hydrofoil section in steady flow. The performance characteristics of the flukes of the fin whale were estimated by using this method. The effects of the different correction factors, and of the frictional drag of the fluke sections, are emphasized. Frictional effects in particular were found to reduce the hydrodynamic efficiency of the flukes significantly. The results are discussed and compared with the known characteristics of fin-whale swimming.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1287","pages":"175-200"},"PeriodicalIF":0.0,"publicationDate":"1989-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0043","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13713380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relation of elevation of cytosolic free calcium to activation of membrane conductance in rat parotid acinar cells.","authors":"P T Gray","doi":"10.1098/rspb.1989.0039","DOIUrl":"https://doi.org/10.1098/rspb.1989.0039","url":null,"abstract":"<p><p>The relation between elevation of cytosolic free calcium and activation of membrane conductance has been studied in single acinar cells of the rat parotid. Outward and inward currents are activated by calcium elevation and oscillate in phase with oscillations of cytosolic calcium. The outward current results from activation of a large unit-conductance Ca2+ and voltage-dependent K+ channel, whereas the inward current is most likely carried predominantly by Cl-. Both these conductances have been previously described in exocrine cells. Buffering calcium at resting levels eliminated current responses to muscarinic agonists, suggesting that calcium is the only significant second messenger involved in the short-term control of this conductance by acetylcholine.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"99-107"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13620196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Epithelial action potentials in embryos of the Australian lungfish.","authors":"Q Bone,&nbsp;A Kemp,&nbsp;D Kemp","doi":"10.1098/rspb.1989.0041","DOIUrl":"https://doi.org/10.1098/rspb.1989.0041","url":null,"abstract":"<p><p>The epithelial cells of the skin of embryonic Australian lungfish (Neoceratodus forsteri) between stages 30 and 39, are mechanosensitive and excitable, showing overshooting action potentials 400-800 ms long with a rapid rise followed by a slower repolarization (usually with a shoulder on the repolarizing phase), which propagate at around 10 mm s-1. This skin impulse system is very similar to that found in embryonic and larval Amphibia; the significance of this similarity is discussed.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"127-31"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0041","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13712079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Florey lecture, 1988. From egg to embryo: the initiation of cell differentiation in Amphibia.","authors":"J B Gurdon","doi":"10.1098/rspb.1989.0033","DOIUrl":"https://doi.org/10.1098/rspb.1989.0033","url":null,"abstract":"<p><p>Some of the principles by which different cell types first arise at the beginning of animal development are illustrated by muscle cell formation in Amphibia. If the nucleus of a differentiated muscle cell is transplanted to an enucleated egg, some of the resulting embryos develop into tadpoles with a wide range of normally differentiated cells. These experiments show that genes undergo major changes in activity as a response to components of egg cytoplasm. Two fundamental mechanisms account for the regional activation of genes in early embryos. One involves the effect of localized 'determinants' in egg cytoplasm, and the other concerns cell interactions or embryonic induction. Both these mechanisms seem to be responsible for muscle cell formation in amphibian development. The old problem of embryonic induction has recently become accessible to analysis at the molecular level, especially in the case of the mesoderm or muscle-forming induction. This has been greatly facilitated by using a sensitive and quantitative assay to detect the first transcripts of muscle genes a few hours after the start of induction. The role of early events and of interactions among like cells during response to induction is discussed. In analysing specific gene activation following induction, DNA injection into fertilized eggs has shown that a very small part of the cardiac actin gene promoter is sufficient to enable it to respond to induction. Although the experimental work summarized here has been done on amphibian embryos, which are more suitable than other embryos for embryological manipulation, the conclusions reached are believed to be generally applicable to the development of other organisms.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"11-25"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13712078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Responses of synchronous L5178Y S/S cells to heavy ions and their significance for radiobiological theory.","authors":"J T Lett,&nbsp;A B Cox,&nbsp;M D Story,&nbsp;U K Ehmann,&nbsp;E A Blakely","doi":"10.1098/rspb.1989.0034","DOIUrl":"https://doi.org/10.1098/rspb.1989.0034","url":null,"abstract":"<p><p>Synchronous suspensions of the radiosensitive S/S variant of the L5178Y murine leukaemic lymphoblast at different positions in the cell cycle were exposed aerobically to segments of heavy-ion beams (20Ne, 28Si, 40Ar, 56Fe and 93Nb) in the Bragg plateau regions of energy deposition. The incident energies of the ion beams were in the range of 460 +/- 95 MeV u-1, and the calculated values of linear energy transfer (LET infinity) for the primary nuclei in the irradiated samples were 33 +/- 3, 60 +/- 3, 95 +/- 5, 213 +/- 21 and 478 +/- 36 keV microns-1, respectively; 280 kVp X-rays were used as the baseline radiation. Generally, the maxima or inflections in relations between relative biological effectiveness (RBE) and LET infinity were dependent upon the cycle position at which the cells were irradiated. Certain of those relations were influenced by post-irradiation hypothermia. Irradiation in the cell cycle at mid-G1 to mid-G1 + 3 h, henceforth called G1 to G1 + 3 h, resulted in survival curves that were close approximations to simple exponential functions. As the LET infinity was increased, the RBE did not exceed 1.0, and by 478 keV microns-1 it had fallen to 0.39. Although similar behaviour has been reported for inactivation of proteins and certain viruses by ionizing radiations, so far the response of the S/S variant is unique for mammalian cells. The slope of the survival curve for X-photons (D0: 0.27 Gy) is reduced in G1 to G1 + 3 h by post-irradiation incubation at hypothermic temperatures and reaches a minimum (Do: 0.51 Gy) at 25 degrees C. As the LET infinity was increased, however, the extent of hypothermic recovery was reduced progressively and essentially was eliminated at 478 keV microns-1. At the cycle position where the peak of radioresistance to X-photons occurs for S/S cells, G1 + 8 h, increases in LET infinity elicited only small increases in RBE (at 10% survival), until a maximum was reached around 200 keV microns-1. At 478 keV microns-1, what little remained of the variation in response through the cell cycle could be attributed to secondary radiations (delta rays) and smaller nuclei produced by fragmentation of the primary ions.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"27-42"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13712080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The determination of kinetic parameters for carrier-mediated transport of non-labelled substrate analogues: a general method applied to the study of divalent anion transport in placental membrane vesicles.","authors":"R Deves,&nbsp;C A Boyd","doi":"10.1098/rspb.1989.0038","DOIUrl":"https://doi.org/10.1098/rspb.1989.0038","url":null,"abstract":"<p><p>A method is described that allows the determination of kinetic parameters for carrier-mediated transport of unlabelled compounds. The ability of these compounds to relieve the inhibition of labelled substrate efflux produced by addition of an external competitive inhibitor is studied. The method is of general applicability and does not depend upon any intrinsic asymmetry in the ratio of the rates of translocation of the loaded and unloaded carrier. In this paper it is used in a study of the human placental sulphate transporter. Experiments on brush-border membrane vesicles show the method to predict quantitatively kinetic parameters for unlabelled sulphate entry. Further analysis shows this carrier to have a broad specificity for other oxyanions (selenate, tung-state, molybdate and chromate) with the following selectivity sequence: for rate of translocation, SO4, SeO4 greater than WO4 greater than MoO4 much greater than CrO4; for binding affinity, CrO4 greater than MoO4, WO4 greater than SO4, SeO4.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"85-97"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13712082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The stability of ecosystems.","authors":"T Hogg,&nbsp;B A Huberman,&nbsp;J M McGlade","doi":"10.1098/rspb.1989.0035","DOIUrl":"https://doi.org/10.1098/rspb.1989.0035","url":null,"abstract":"<p><p>Stability criteria and phase boundaries for complex ecosystems are obtained and contrasted with previously studied scenarios. The stability of such systems is determined by the behaviour of the largest eigenvalue of matrices governing the response of the system to small perturbations. As a result we show that ecosystems with unstructured cooperative interactions between arbitary species can be less stable than had been previously determined. We also examine hierarchical ecologies, and demonstrate their increased stability under certain conditions.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"43-51"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13712081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Block of an insect central nervous system GABA receptor by cyclodiene and cyclohexane insecticides.","authors":"K A Wafford,&nbsp;S C Lummis,&nbsp;D B Sattelle","doi":"10.1098/rspb.1989.0036","DOIUrl":"https://doi.org/10.1098/rspb.1989.0036","url":null,"abstract":"<p><p>The effects of a cyclodiene (endrin) and a cyclohexane (lindane) insecticide have been tested on gamma-aminobutyric acid (GABA) receptors in the central nervous system of the cockroach (Periplaneta americana), by using electrophysiological methods and an in vitro functional receptor assay. In electrophysiological experiments on an identified motor neuron (Df), endrin blocked the GABA response with a 50% inhibition concentration of 5.0 x 10(-7) M in a non-competitive manner. The actions of endrin were irreversible under the experimental conditions adopted. Increasing the intracellular chloride concentration reduced the effectiveness of endrin, whereas a change in the potassium concentration failed to influence the block by endrin of GABA responses. Lindane exhibited similar actions to endrin on insect GABA receptors, but was approximately an order of magnitude less effective. In a microsac preparation from cockroach nerve cords, endrin, at a concentration of 1.0 x 10(-5) M, completely blocked GABA-stimulated 36Cl- uptake, whereas the same concentration of lindane was less potent, only blocking about 40% of uptake under similar conditions. Neither insecticide had any effect on L-glutamate-activated chloride channels. The results demonstrate that endrin and lindane block functional insect neuronal GABA receptors.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"237 1286","pages":"53-61"},"PeriodicalIF":0.0,"publicationDate":"1989-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1989.0036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13620195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}