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Bio Systems

Kirti Prakash, David Fournier
Histones are punctuated with small chemical modifications that alter their interaction with DNA. One attractive hypothesis stipulates that certain combinations of these histone modifications may function, alone or together, as a part of a predictive histone code to provide ground rules for chromatin folding. We consider four features that relate histone modifications to chromatin folding: charge neutralisation, molecular specificity, robustness and evolvability. Next, we present evidence for the association among different histone modifications at various levels of chromatin organisation and show how these relationships relate to function such as transcription, replication and cell division...
November 17, 2017: Bio Systems
Abicumaran Uthamacumaran
No abstract text is available yet for this article.
November 17, 2017: Bio Systems
Antonio Barrera, Patricia Román-Román, Francisco Torres-Ruiz
A stochastic diffusion process, whose mean function is a hyperbolastic curve of type I, is presented. The main characteristics of the process are studied and the problem of maximum likelihood estimation for the parameters of the process is considered. To this end, the firefly metaheuristic optimization algorithm is applied after bounding the parametric space by a stagewise procedure. Some examples based on simulated sample paths and real data illustrate this development.
November 9, 2017: Bio Systems
Marco Baralle, Francisco Ernesto Baralle
This issue dedicated to the code of life tackles very challenging and open questions in Biology. The genetic code, brilliantly uncovered over 50 years ago is an example of a univocal biological code. In fact, except for very few and marginal variations, it is the same from bacteria to man, the RNA stretch: 5' GUGUUC 3' reads as the dipeptide: Val-Phe in bacteria, in yeast, in Arabidopsis, in zebra fish, in mouse and in human. A degree of ambiguity is possible if mutations are introduced in the tRNAs in a way that the anticodon reads one amino acid but the aminoacyl-transferase attaches a different one onto the tRNA...
November 6, 2017: Bio Systems
Luc Steels, Eörs Szathmáry
The well-established framework of evolutionary dynamics can be applied to the fascinating open problems how human brains are able to acquire and adapt language and how languages change in a population. Schemas for handling grammatical constructions are the replicating unit. They emerge and multiply with variation in the brains of individuals and undergo selection based on their contribution to needed expressive power, communicative success and the reduction of cognitive effort. Adopting this perspective has two major benefits...
November 6, 2017: Bio Systems
Animesh Kumar Paul, Pintu Chandra Shill
The product of gene expression works together in the cell for each living organism in order to achieve different biological processes. Many proteins are involved in different roles depending on the environment of the organism for the functioning of the cell. In this paper, we propose gene ontology (GO) annotations based semi-supervised clustering algorithm called GO fuzzy relational clustering (GO-FRC) where one gene is allowed to be assigned to multiple clusters which are the most biologically relevant behavior of genes...
November 4, 2017: Bio Systems
Morten Tønnessen
In this paper, it is argued that Jakob von Uexküll's "search image" notion, the original version of this notion within ethology, is still of use. A search image, in Uexküll's sense, is an imagined object that an organism has in mind when it searches for something. Uexküll's conception of the search image is useful both for understanding the theoretical context of contemporary notions of search images, and with an eye to envisioning possible future developments of the idea. Uexküll's classical notion differs from contemporary versions in that it has a wider application, and is therefore of greater relevance to theoretical biology and cognitive science...
November 4, 2017: Bio Systems
Marcella Faria
Adhesion is a central mechanism in the development of multicellular life. It underlies cell movement, communication and differentiation. Remarkably, the presence of only three classes of interconnected molecules is sufficient to establish functional adhesive interactions between cells: Extracellular Matrix components (ECMs); Cell Adhesion Molecules (CAMs); and cytoskeleton microfilaments. In the present work, we shall dissect the nature and the dynamical interactions between these three classes of molecules as they appear in evolution, to postulate that their organization into an organic code sensu Barbieri(1) parallels the development of multicellularity...
November 1, 2017: Bio Systems
Meghan Timmins, Daniel Ashlock
Graphs can be used as contact networks in models of epidemic spread. Most research seeks to extract the properties of an extant graph, derived from questionnaires or other sources of contact information. The inverse problem of searching the space of graphs for those that exhibit specific properties has received little attention and that is the focus of this study. This is, in part, because searching the space of contact networks is difficult. This paper extends and tests a representation for searching the space of contact networks with evolutionary computation...
October 31, 2017: Bio Systems
Neil Phillips, Andrew Adamatzky, Richard Mayne
No abstract text is available yet for this article.
October 30, 2017: Bio Systems
Debraj Ghosh, Rajat K De
The stochastic simulation algorithm (SSA) based modeling is a well recognized approach to predict the stochastic behavior of biological networks. The stochastic simulation of large complex biochemical networks is a challenge as it takes a large amount of time for simulation due to high update cost. In order to reduce the propensity update cost, we proposed two algorithms: slow update exact stochastic simulation algorithm (SUESSA) and slow update exact sorting stochastic simulation algorithm (SUESSSA). We applied cache-based linear search (CBLS) in these two algorithms for improving the search operation for finding reactions to be executed...
October 30, 2017: Bio Systems
Nikola Štambuk, Paško Konjevoda, Petra Turčić, Katalin Kövér, Renata Novak Kujundžić, Zoran Manojlović, Mario Gabričević
Sense and antisense peptides, i.e. peptides specified by complementary DNA and RNA sequences, interact with increased probability. Biro, Blalock, Mekler, Root-Bernstein and Siemion investigated the recognition rules of peptide-peptide interaction based on the complementary coding of DNA and RNA sequences in 3'→5' and 5'→3' directions. After more than three decades of theoretical and experimental investigations, the efficiency of this approach to predict peptide-peptide binding has been experimentally verified for more than 50 ligand-receptor systems, and represents a promising field of research...
October 28, 2017: Bio Systems
Ronny Straube
Much of the complexity of regulatory networks derives from the necessity to integrate multiple signals and to avoid malfunction due to cross-talk or harmful perturbations. Hence, one may expect that the input-output behavior of larger networks is not necessarily more complex than that of smaller network motifs which suggests that both can, under certain conditions, be described by similar equations. In this review, we illustrate this approach by discussing the similarities that exist in the steady state descriptions of a simple bimolecular reaction, covalent modification cycles and bacterial two-component systems...
October 28, 2017: Bio Systems
George Svetlichny
We introduce a quantum model system incorporating qualitative aspects of tunneling in enzyme action and analyze the possibilities of quantum superposition of several conformations of the enzyme-substrate complex. There is a potential barrier in each conformation which for simplicity's sake is assumed to be of zero width making the system explicitly solvable. Such a system exhibits generic features of quantum dynamics that should be present to some extent in real enzyme action. We find that depending on the parameters of the system, the rate of conversion of substrate to product can be either enhanced or suppressed in relation to the rates that can be achieved in fixed conformations...
October 21, 2017: Bio Systems
Veit Grabe, Silke Sachse
Sensory coding represents a basic principle of all phyla in nature: species attempt to perceive their natural surroundings and to make sense of them. Ultimately, sensory coding is the only way to allow a species to make the kinds of crucial decisions that lead to a behavioral response. In this manner, animals are able to detect numerous parameters, ranging from temperature and humidity to light and sound to volatile or non-volatile chemicals. Most of these environmental cues represent a clearly defined stimulus array that can be described along a single physical parameter, such as wavelength or frequency; odorants, in contrast, cannot...
October 17, 2017: Bio Systems
Plamen L Simeonov
The goal of this paper is to advance an extensible theory of living systems using an approach to biomathematics and biocomputation that suitably addresses self-organized, self-referential and anticipatory systems with multi-temporal multi-agents. Our first step is to provide foundations for modelling of emergent and evolving dynamic multi-level organic complexes and their sustentative processes in artificial and natural life systems. Main applications are in life sciences, medicine, ecology and astrobiology, as well as robotics, industrial automation, man-machine interface and creative design...
October 16, 2017: Bio Systems
Mário Saleiro, Kasim Terzić, J M F Rodrigues, J M H du Buf
Learning robust keypoint descriptors has become an active research area in the past decade. Matching local features is not only important for computational applications, but may also play an important role in early biological vision for disparity and motion processing. Although there were already some floating-point descriptors like SIFT and SURF that can yield high matching rates, the need for better and faster descriptors for real-time applications and embedded devices with low computational power led to the development of binary descriptors, which are usually much faster to compute and to match...
October 13, 2017: Bio Systems
Ádám Kun, Ádám Radványi
The origin of the genetic code and translation is a "notoriously difficult problem". In this survey we present a list of questions that a full theory of the genetic code needs to answer. We assess the leading hypotheses according to these criteria. The stereochemical, the coding coenzyme handle, the coevolution, the four-column theory, the error minimization and the frozen accident hypotheses are discussed. The integration of these hypotheses can account for the origin of the genetic code. But experiments are badly needed...
October 12, 2017: Bio Systems
Vladimir Kubyshkin, Carlos G Acevedo-Rocha, Nediljko Budisa
The complete ribosomal protein synthesis cycle and codon-amino acids associations are universally preserved in all life taxa on Earth. This process is accompanied by a set of hierarchically organized recognition and controlling events at different complexity levels. It starts with amino acid activation by aminoacyl tRNA synthetases (aaRS) followed by matching with the acceptor units of their cognate tRNAs ("operational RNA code") and ribosomal codon-anticodon pairing of messenger RNA ("triplet code"). However, this codon-anticodon matching is possible only when protein translation machinery (translation factors, ribosome) accepts an esterified amino acid...
October 10, 2017: Bio Systems
Marcello Barbieri
Various independent discoveries have shown that many organic codes exist in living systems, and this implies that they came into being during the history of life and contributed to that history. The genetic code appeared in a population of primitive systems that has been referred to as the common ancestor, and it has been proposed that three distinct signal processing codes gave origin to the three primary kingdoms of Archaea, Bacteria and Eukarya. After the genetic code and the signal processing codes, on the other hand, only the ancestors of the eukaryotes continued to explore the coding space and gave origin to splicing codes, histone code, tubulin code, compartment codes and many others...
October 6, 2017: Bio Systems
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