Advances in Biophysics最新文献

{"title":"The neuronal basis of visual memory and imagery in the primate: a neurophysiological approach.","authors":"K Nakahara,&nbsp;M Ohbayashi,&nbsp;H Tomita,&nbsp;Y Miyashita","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>To understand the biological basis of memory is one of the most exciting frontiers of science. Single unit recording is a powerful method to investigate neuronal correlates of various brain functions such as memory in awake animals. Anatomical, neuropsychological, and neurophysiological evidence indicates that the IT has an important role not only for synthesizing the analyzed visual attribute into a unique configuration, but also for the storehouse of visual memory in humans and primates. We performed single unit recordings in the primate IT, and found neuronal correlates of visual long-term memory: the IT neurons could reflect learned associative relations among stimuli. The findings reviewed here support the hypothesis that the IT is a region of the brain where visual perception meets memory and imagery.</p>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"35 ","pages":"103-19"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20854932","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":"Notice to authors","authors":"","doi":"10.1016/S0065-227X(98)90001-6","DOIUrl":"https://doi.org/10.1016/S0065-227X(98)90001-6","url":null,"abstract":"","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"35 ","pages":"Page vii"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(98)90001-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136923703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neural systems for control of voluntary action — A hypothesis","authors":"Okihide Hikosaka","doi":"10.1016/S0065-227X(98)80004-X","DOIUrl":"10.1016/S0065-227X(98)80004-X","url":null,"abstract":"<div><p>Action is the means by which we and animals survive. It consists of a complex combination of movements which are either innately endowed or acquired by learning. In this article, I propose a hypothesis on the relationship between the organization of action and the organization of the brain. Innate and learned actions are controlled by different levels of neural networks: innate actions are controlled by reflex mechanisms and pattern generators in the spinal cord and brainstem, while learned actions are controlled by the cerebral cortex, basal ganglia, and cerebellum. However, these mechanisms are by no means independent. Phylogenetically, animals have acquired progressively more complex actions by gaining neural connections between different neural mechanisms. This is accomplished by the connection from newly evolving brain structures, particularly the cerebral cortex, to reflex or pattern generator mechanisms, as typically observed in the neural mechanism for saccadic eye movement. The cerebral cortex is a general purpose device which can be used in different ways depending on biological demands; in other words, it is used for learned actions. In consequence, a given movement (<em>e.g.</em>, saccade) can be produced by different neural circuits, all converging onto the movement generation mechanism (<em>e.g.</em>, SC) in an excitatory manner. However, such converging inputs that promote actions are likely to produce a chaotic explosion of neural signals. There must be some way to prevent the explosion and select signals that are most appropriate for the current behavioral context. The basal ganglia system evolved to accomplish this goal. It exerts a powerful inhibition on its targets in the brainstem (<em>e.g.</em>, SC) and the thalamo-cortical system, thereby closing the gate for the action-promoting excitatory inputs; it also removes the sustained inhibition using another inhibition originating in the striatum (input structure of the basal ganglia), thereby opening the gate so that an appropriate action is executed. There are at least two additional functions of the basal ganglia. First, the selection mechanism of the basal ganglia is used also for the selection of simulated actions (<em>e.g.</em>, thoughts) which are largely controlled by the association cortices. Second, it is used for learning of behavioral procedures: various kinds of signals from the cerebral cortex converge onto neurons in the basal ganglia to generate temporary association of neural signals, whose behavioral significance is evaluated by signals from the limbic system via dopaminergic neurons. The procedural memories thus created (perhaps in the cerebral cortex, particularly premotor cortices) are then used to guide learning of individual movements in which the cerebellum plays a crucial role. Thus, the implementation of learned actions is carried out by two distinct neural systems, each forming a loop circuit: 1) cerebral cortex and basal ganglia; 2) cerebral co","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"35 ","pages":"Pages 81-102"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(98)80004-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55849893","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":"Significant role of electrostatic interactions for stabilization of protein assemblies","authors":"Takuya Takahashi","doi":"10.1016/S0065-227X(97)89630-X","DOIUrl":"10.1016/S0065-227X(97)89630-X","url":null,"abstract":"<div><p>Contribution of electrostatic interactions to stability of BPTI orthorhombic, pig-insulin cubic crystals, and horse L ferritin crystals was evaluated with numerical calculation of Poisson-Boltzmann equation based on a dielectric model. The stability of a ferritin molecule (24-mer) composed of 24 subunits was also evaluated. It was found that the surface charge-charge interactions at separation distances (&lt; 5 Å) were insensitive to variations in the ionic strength, and thus stabilized assembled states of the proteins (<em>i.e.</em>, crystalline state and oligomeric state). It was also revealed that the charge density and the packing of the protein crystals were largely responsible for the ionic strength dependence of the crystal stability. The stability of the 5PTI crystalline state with a high charge density drastically increased as the concentration of the solvent ions increased. In contrast, that of the insulin crystal with a low charge density and large solvent region was insensitive to changes in the ionic concentration. The electrostatic interaction between ferritin 24-mers was attributed to two salt bridges mediated by Cd ion. For the stability of the ferritin 24-mer, which is evolutionally designed, the electrostatic stabilization between the subunits was attributed to polar bonds such as buried salt bridges or hydrogen bonds, which occasionally yielded more than 5 kcal/mol and were numerous and very strong compared with the bonds between molecules in the 5PTI and 9INS crystals.</p><p>By analyzing the atomic charge-charge interactions in detail, it was found that charge pairs separated by less than 3 Å, such as hydrogen bonds, dominantly stabilize the assembled states, and that pairs 3 to 5 Å apart were also important. The stability of the assembled states evaluated by the total <em>EET</em> was determined by the fine balance between the two competing contributions arising from the stabilizing atoms and the destabilizing atoms.</p><p>Changes of the <em>ASA</em> and hydration free energy were also evaluated in accordance with the process of the subunit assembly. The change of hydration free energy, which was very large (<em>i.e.</em>, ~+ 100 kcal/mol/subunit) and unfavorable for the assembly, was proportional to the electrostatic hydration energy (<em>i.e.</em>, Born energy change in the hydration process). Hydrophobic groups were likely to appear more frequently than hydrophilic groups at the interfaces.</p><p>This study offers a method which can improve the stability of protein crystals by introducing polar or charged residues that are properly designed to form specific hydrogen bonds or salt bridges between neighboring protein molecules. This method is also applicable to crystallography, because it improves refinement of protein structures in crystals by taking the inter-protein interactions into account.</p></div>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 41-54"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89630-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20149327","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":"Novel biosensoric devices based on molecular protein hetero-multilayer films","authors":"Anke Diederich ,&nbsp;Mathias Lösche","doi":"10.1016/S0065-227X(97)89641-4","DOIUrl":"10.1016/S0065-227X(97)89641-4","url":null,"abstract":"<div><p>We have developed a novel concept for the modification of technical surfaces with molecularly well-organized layers of bioorganic components. A molecular construction set has been used to implement this concept which is based on molecularly stratified polyelectrolyte films as a structure decoupling protein layers from solid substrates. Utilizing this technology, one can start from a number of different substrates to obtain the same surface structures, on which protein hetero-multilayer films can be prepared to functionalize the interface for (potentially very different) purposes. We have demonstrated the viability of this concept by constructing a biosensor surface that was characterized by x-ray, spectroscopic, and immunological techniques. For the preparation of this functionalized interface, a cascade of biospecific recognition processes has been used, in which a layer of SpA was supplanted on a dense SA monolayer (binding stoichiometry, 0̃.2 SpA/SA). On the SpA, IgG has been immobilized (binding stoichiometry, 0̃.5 IgG/ SpA). The resultant biosensor displays extremely low unspecific background reactivity, high sensitivity, and good response linearity over more than 3 orders of magnitude in antigen concentration.</p></div>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 205-230"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89641-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20149825","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":"Natural and artificial carbohydrate-glued protein aggregates","authors":"Keiko Matsubara ,&nbsp;Satoshi Ebina","doi":"10.1016/S0065-227X(97)89643-8","DOIUrl":"10.1016/S0065-227X(97)89643-8","url":null,"abstract":"<div><p>Carbohydrate gluing (which may have a carbohydrate-lectin binding mechanism) was first recognized as a major contributor in the supramolecular assembly of annelid giant Hb from the marine-worm <em>P. aibuhitensis</em>. Although this assembly obviously also relies on protein-protein interactions, the authors tested the application of carbohydrate gluing in the assembly of a protein aggregate using a lectin and a carbohydrate-containing protein. The resultant aggregate was a mixture of the protein aggregate and the ingredient proteins. The significance of the method is that the assembly of the aggregate can be controlled by using a hapten sugar. This controllability, in conjunction with newly developing glyco-technology, has great potential for the construction of arbitrary protein molecules into a regular protein aggregate, thereby providing sophisticated functions.</p></div>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 253-262"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89643-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20149827","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":"Electron crystallography of macromolecular periodic arrays on phospholipid monolayers","authors":"Wah Chiu,&nbsp;Agustin J. Avila-Sakar ,&nbsp;Michael F. Schmid","doi":"10.1016/S0065-227X(97)89638-4","DOIUrl":"10.1016/S0065-227X(97)89638-4","url":null,"abstract":"<div><p>Electron crystallography has the potential of yielding structural information equivalent to x-ray diffraction. The major difficulty has been preparing specimens with the required structural order and size for diffraction and imaging in the electron microscope. 2D crystallization on phospholipid monolayers is capable of fulfilling both of these requirements. Crystals can form as a result of specific interactions with a protein's ligand or an analog, suitably linked to a lipid tail; or on a surface of complementary head-group charge. With such choices, the availability of a suitable lipid is limited only by synthetic chemistry. Ultimately, it is the quality and regularity of the protein-protein interactions that determine the crystalline order, as it is with any protein crystal. In the case of streptavidin, the monolayer crystal diffracts beyond 2.5 Å. A 3 Å projection map reconstructed from electron diffraction amplitudes and phases from images shows density which can be interpreted as β-sheets and clusters of side chains. It remains to be shown that the monolayer crystals are flat and diffract as well at high tilt angle as untilted. Technological issues such as charging must be resolved. With parallel advances in data collection and processing, electron crystallography of monolayer macromolecular crystals will eventually take its place beside x-ray crystallography and NMR as a routine and efficient structural technique.</p></div>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 161-172"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89638-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20149986","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 influence of protein and interfacial structure on the self-assembly of oriented protein arrays","authors":"Deborah E. Leckband","doi":"10.1016/S0065-227X(97)89639-6","DOIUrl":"10.1016/S0065-227X(97)89639-6","url":null,"abstract":"<div><p>These results demonstrate the complexity of factors that impact the self-assembly of protein arrays via the specific binding to receptor-functionalized interfaces. Both the composition and colloidal properties of the protein and target membrane surfaces will affect the proteinsurface interactions. However, different structural features control the interactions over different distance regimes and with different consequences. The long-range interactions that control the adsorption kinetics are sensitive not only to the charge on the target surface but also by the topological charge distribution on the protein exterior. Short-range repulsive interactions rooted in both the protein topology and in the membrane structure, by contrast, can significantly alter both the rates and strengths binding. Consequently, the effective design of self-assembling protein arrays must consider not only the recognition interactions that drive such self-organization, but also the details of the microenvironment and their impact on molecular recognition events.</p></div>","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 173-190"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89639-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20149987","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":"Contributor sketches","authors":"","doi":"10.1016/S0065-227X(97)90085-X","DOIUrl":"https://doi.org/10.1016/S0065-227X(97)90085-X","url":null,"abstract":"","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages 263-269"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)90085-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136585244","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":"Preface to volume 34","authors":"","doi":"10.1016/S0065-227X(97)89626-8","DOIUrl":"https://doi.org/10.1016/S0065-227X(97)89626-8","url":null,"abstract":"","PeriodicalId":50880,"journal":{"name":"Advances in Biophysics","volume":"34 ","pages":"Pages vii-viii"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0065-227X(97)89626-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134831013","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}