The elastic fiber. I. The separation and partial characterization of its macromolecular components

The two morphologically different constituents of the mature elastic fiber, the central amorphous and the peripheral microfibrillar components, have been separated and partially characterized. A pure preparation of elastic fibers was obtained from fetal bovine ligamentum nuchae by extraction of the homogenized ligament with 5 M guanidine followed by digestion with collagenase. The resultant preparation consisted of elastic fibers which were morphologically identical with those seen in vivo. The microfibrillar components of these elastic fibers were removed either by proteolytic enzymes or by reduction of disulfide bonds with dithioerythritol in 5 M guanidine. The microfibrils solubilized by both methods were rich in polar, hydroxy, and sulfur-containing amino acids and contained less glycine, valine, and proline than the amorphous component of the elastic fiber. In contrast, the amino acid composition of the amorphous component was identical with that previously described for elastin. This component demonstrated selective susceptibility to elastase digestion, but was relatively resistant to the action of other proteolytic enzymes and to reduction. These observations establish that the microfibrils consist of a different connective tissue protein (or proteins) that is neither collagen nor elastin. During embryologic development the microfibrils form an aggregate structure before the amorphous component is secreted. These microfibrils may therefore play a primary role in the morphogenesis of the elastic fiber.     

Principle of parametric ion separation in a molecular model of the sodium pump

Expressions were obtained for separation coefficients of sodium and potassium ions in macroscopic and molecular models of the sodium pump. Conjugation between the energy-donor process at ATP hydrolysis and ion transport is achieved at the expense of synchroneous changes of the affinity of ion-binding centers and divided cations. i. e. the cyclic changes of energetic profiles in the membrane for each type of ions. The division coefficient in the stationary state is equal to the product of relative changes in selectivity towards the cations of the enzyme ion-binding centers in phosporylated and unphosphorylated states.     

The membrane components of crustacean neuromuscular systems. I. Immunity of different electrogenic components to tetrodotoxin and saxitoxin

Axon spikes in crayfish and lobster neuromuscular preparations were blocked by tetrodotoxin or saxitoxin (concentration 10⁻⁹ to 10⁻⁸ g/ml). Responses evoked in the excitatory synaptic membrane by ionophoretically applied glutamate, or in the inhibitory by GABA were unaffected by concentrations of the poisons up to 10⁻⁵ g/ml. These confirm other findings that the poisons do not affect electrically inexcitable membrane components. “Miniature” p.s.p.’s, which indicate local secretory activity in the presynaptic terminals were unaffected by the poisons. Electrical stimuli applied to the axon terminals elicited localized p.s.p.’s after spike electrogenesis of the axons was blocked. Thus, persistence of secretory activity may be linked to persistence of depolarizing K activation in the axons. Spikes induced in the muscle fibers by procaine were not affected by the poisons. In correlation with other data this finding indicates that the depolarizing electrogenic element, which does not depend upon Na activation in the normally gradedly responsive muscles, differs chemically from the Na activation component which is present in the conductile membrane of various cells. Three other varieties of electrically excitable response which are present in crayfish muscle fibers (hyperpolarizing Cl activation, depolarizing K inactivation, and K activation) were, likewise, immune to the toxin.     

The physical mechanism of calcium pump regulation in the heart.

The Ca-ATPase in the cardiac sarcoplasmic reticulum membrane is regulated by an amphipathic transmembrane protein, phospholamban. We have used time-resolved phosphorescence anisotropy to detect the microsecond rotational dynamics, and thereby the self-association, of the Ca-ATPase as a function of phospholamban phosphorylation and physiologically relevant calcium levels. The phosphorylation of phospholamban increases the rotational mobility of the Ca-ATPase in the sarcoplasmic reticulum bilayer, due to a decrease in large-scale protein association, with a [Ca2+] dependence parallel to that of enzyme activation. These results support a model in which phospholamban phosphorylation or calcium free the enzyme from a kinetically unfavorable associated state.     

Macroscopic separation of charges in a pulsed electric discharge

The possibility of separating charges in an ordinary electric discharge was demonstrated. The luminous object formed after the end of the discharge was found to exist over a few hundred milliseconds, or six orders of magnitude longer than the lifetime of an ideal plasma of the same volume. It is shown that the luminous object has a negative electric charge and has no free charged particles of opposite sign.     

BioMOBY successfully integrates distributed heterogeneous bioinformatics Web Services. The PlaNet exemplar case

The burden of non-interoperability between on-line genomic resources is increasingly the rate-limiting step in large-scale genomic analysis. BioMOBY is a biological Web Service interoperability initiative that began as a retreat of representatives from the model organism database community in September, 2001. Its long-term goal is to provide a simple, extensible platform through which the myriad of on-line biological databases and analytical tools can offer their information and analytical services in a fully automated and interoperable way. Of the two branches of the larger BioMOBY project, the Web Services branch (MOBY-S) has now been deployed over several dozen data sources worldwide, revealing some significant observations about the nature of the integrative biology problem; in particular, that Web Service interoperability in the domain of bioinformatics is, unexpectedly, largely a syntactic rather than a semantic problem. That is to say, interoperability between bioinformatics Web Services can be largely achieved simply by specifying the data structures being passed between the services (syntax) even without rich specification of what those data structures mean (semantics). Thus, one barrier of the integrative problem has been overcome with a surprisingly simple solution. Here, we present a non-technical overview of the critical components that give rise to the interoperable behaviors seen in MOBY-S and discuss an exemplar case, the PlaNet consortium, where MOBY-S has been deployed to integrate the on-line plant genome databases and analytical services provided by a European consortium of databases and data service providers.     

SaMW: a probabilistic meta-heuristic algorithm for job scheduling in heterogeneous distributed systems powered by microservices

Cluster Computing - Applications are evolving in ways that demand geographically distributed resources to co-operate in order to give users better Quality of Service (QoS). There is a plethora of...     

Networked buffering: a basic mechanism for distributed robustness in complex adaptive systems

A generic mechanism - networked buffering - is proposed for the generation of robust traits in complex systems. It requires two basic conditions to be satisfied: 1) agents are versatile enough to perform more than one single functional role within a system and 2) agents are degenerate, i.e. there exists partial overlap in the functional capabilities of agents. Given these prerequisites, degenerate systems can readily produce a distributed systemic response to local perturbations. Reciprocally, excess resources related to a single function can indirectly support multiple unrelated functions within a degenerate system. In models of genome:proteome mappings for which localized decision-making and modularity of genetic functions are assumed, we verify that such distributed compensatory effects cause enhanced robustness of system traits. The conditions needed for networked buffering to occur are neither demanding nor rare, supporting the conjecture that degeneracy may fundamentally underpin distributed robustness within several biotic and abiotic systems. For instance, networked buffering offers new insights into systems engineering and planning activities that occur under high uncertainty. It may also help explain recent developments in understanding the origins of resilience within complex ecosystems.