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Theory in Biosciences, Theorie in Den Biowissenschaften

Hidekazu Yoshioka, Yuta Yaegashi
Comprehending life history of migratory fish, onset of migration in particular, is a key biological and ecological research topic that still has not been clarified. In this paper, we propose a simple mathematical model for the onset of fish migration in the context of a stochastic optimal stopping theory, which is a new attempt to our knowledge. Finding the criteria of the onset of migration reduces to solving a variational inequality of a degenerate elliptic type. As a first step of the new mathematical modeling, mathematical and numerical analyses with particular emphasis on whether the model is consistent with the past observation results of fish migration are examined, demonstrating reasonable agreement between the theory and observation results...
May 2, 2018: Theory in Biosciences, Theorie in Den Biowissenschaften
Nataliia Kodash, Martin Fischer
Georgy Gause (1910-1986) is best known for his contribution to ecology and evolutionary theory. His book "The Struggle for Existence" (1934) inspired generations of ecologists. Yet his scientific interests were diverse, embracing many aspects of the life sciences and medicine. The most notable shift in his research took place in the early 1940s when he began to study antibiotics and discovered Gramicidin S. Superficially, this shift looked like an attempt to switch from purely theoretical to applied research during the years of World War II, but Gause's decision may also have been seriously affected by the "Great Purge" and the growth of Lysenkoism...
April 3, 2018: Theory in Biosciences, Theorie in Den Biowissenschaften
Sumana Ghosh, Sandip Banerjee
A mathematical model for the quantitative analysis of cancer-immune interaction, considering the role of antibodies has been proposed in this paper. The model is based on the clinical evidence, which states that antibodies can directly kill cancerous cells (Ivano et al. in J Clin Investig 119(8):2143-2159, 2009). The existence of transcritical bifurcation, which has been proved using Sotomayor theorem, provides strong biological implications. Through numerical simulations, it has been illustrated that under certain therapy (like monoclonal antibody therapy), which is capable of altering the parameters of the system, cancer-free state can be obtained...
March 23, 2018: Theory in Biosciences, Theorie in Den Biowissenschaften
Elena Fimmel, Christian J Michel, Martin Starman, Lutz Strüngmann
Self-complementary circular codes are involved in pairing genetic processes. A maximal [Formula: see text] self-complementary circular code X of trinucleotides was identified in genes of bacteria, archaea, eukaryotes, plasmids and viruses (Michel in Life 7(20):1-16 2017, J Theor Biol 380:156-177, 2015; Arquès and Michel in J Theor Biol 182:45-58 1996). In this paper, self-complementary circular codes are investigated using the graph theory approach recently formulated in Fimmel et al. (Philos Trans R Soc A 374:20150058, 2016)...
April 2018: Theory in Biosciences, Theorie in Den Biowissenschaften
Takayuki Onai
One of the definitive characteristics of chordates (cephalochordates, vertebrates) is the somites, which are a series of paraxial mesodermal blocks exhibiting segmentation. The presence of somites in the basal chordate amphioxus and in vertebrates, but not in tunicates (the sister group of vertebrates), suggests that the tunicates lost the somites secondarily. Somites are patterned from anterior to posterior during embryogenesis. How such a segmental pattern evolved from deuterostome ancestors is mysterious...
April 2018: Theory in Biosciences, Theorie in Den Biowissenschaften
Mohammad Reza Parsaei, Reza Javidan, Narges Shayegh Kargar, Hassan Saberi Nik
In this paper, we study the global properties of a computer virus propagation model. It is, interesting to note that the classical method of Lyapunov functions combined with the Volterra-Lyapunov matrix properties, can lead to the proof of the endemic global stability of the dynamical model characterizing the spread of computer viruses over the Internet. The analysis and results presented in this paper make building blocks towards a comprehensive study and deeper understanding of the fundamental mechanism in computer virus propagation model...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Nicolas Glade, Olivier Bastien, Pascal Ballet
Cellular automata are often used to explore the numerous possible scenarios of what could have occurred at the origins of life and before, during the prebiotic ages, when very simple molecules started to assemble and organise into larger catalytic or informative structures, or to simulate ecosystems. Artificial self-maintained spatial structures emerge in cellular automata and are often used to represent molecules or living organisms. They converge generally towards homogeneous stationary soups of still-life creatures...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Pavle Krsmanovic
Discussions of the survival determinism concept have previously focused on its primary role in the evolution of early unicellular organisms in the light of findings which have been reported on a number of diseases. The rationale for such parallel was in the view according to which multicellular organisms could be regarded as sophisticated colonies of semi-autonomous, single-celled entities, whereby various diseases were described as conditions arising upon the activation of the respective survival mechanisms in a milieu unsuitable for such robust stress response...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Shihong Liu, Yan Yang, Fang Wei, Jifa Duan, Janeen Braynen, Baoming Tian, Gangqiang Cao, Gongyao Shi, Jiachen Yuan
Polyploidy is a widespread feature of plant genomes. As a typical model of polyploidy, autopolyploidy has been postulated evolutionary dead ends and received little attention compared with allopolyploidy. For the limited data available so far, the evolutionary outcome of genome diversity in autopolyploids remains controversial in comparison with its diploid ancestors. In the present study, the effects of autopolyploidy on genome diversity were revealed at a genome-wide scale by comparative analyses of polymorphism between Arabidopsis autopolyploids (autotetraploids and autotriploids) and related diploids within the first ten successive inbred generations using amplified fragment length polymorphism...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Jeffrey K McKee
Hominin evolution in the African Pliocene and Pleistocene was accompanied and mediated by changes in the abiotic and biotic spheres. It has been hypothesized that such environmental changes were catalysts of hominin morphological evolution and speciations. Whereas there is little doubt that ecological changes were relevant to shaping the trajectories of mammalian evolution, testing specific hypotheses with data from the fossil record has yielded ambiguous results regarding environmental disruption as a primary catalyst...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Robert Beyer
In response to the computational limitations of individual leaf-based tree growth models, this article presents a new approach for the efficient characterisation of the spatial distribution of foliage in monolayered trees in terms of 2D foliage surfaces. Much like the recently introduced 3D leaf area density, this concept accommodates local crown plasticity, which is a common weak point in large-scale growth models. Recognizing phototropism as the predominant driver of spatial crown expansion, we define the local light gradient on foliage surfaces...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Jürgen Jost
No abstract text is available yet for this article.
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Anderson A Eduardo, Ricardo Carmo
The concept of biological diversity has inspired important discussions throughout the history of ecology. Although its meaning and usefulness have been questioned, it is currently one of the key artifacts of ecology. One way to try to understand why such a concept has undergone so many discussions is to examine its emergence and history from the epistemology perspective. In the present work, we investigated how the emergence of mechanical objectivity (as an epistemic virtue) and trained judgment affected how ecologists address the concept of biological diversity...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Ľudmila Lacková, Vladimír Matlach, Dan Faltýnek
Arbitrariness in the genetic code is one of the main reasons for a linguistic approach to molecular biology: the genetic code is usually understood as an arbitrary relation between amino acids and nucleobases. However, from a semiotic point of view, arbitrariness should not be the only condition for definition of a code, consequently it is not completely correct to talk about "code" in this case. Yet we suppose that there exist a code in the process of protein synthesis, but on a higher level than the nucleic bases chains...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Hidekazu Yoshioka
A simple game-theoretic model for upstream fish migration, which is a key element in life history of diadromous fishes, is proposed. Foundation of the model is a minimization problem on the cost of migration with the swimming speed and school size as the variables to be simultaneously optimized. Finding the optimizer ultimately reduces to solving a self-consistency equation without explicit solutions. Mathematical analytical results lead to the sufficient condition that the self-consistency equation has a unique solution, which turns out to be identified with the condition where the unique optimizer exists...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
R Wiff, M A Barrientos, A M Segura, A C Milessi
The amount of biomass production per unit of food consumed (P/Q) represents an important quantity in ecosystem functioning, because it indicates how efficient a population transforms ingested food into biomass. Several investigations have noticed that P/Q remains relatively constant (or invariant) across fish population that feed at the same food-type level (carnivorous/herbivorous). Nevertheless, theoretical explanation for this invariant is still lacking. In this paper, we demonstrate that P/Q remains invariant across fish populations with stable-age distribution...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Francesco Catania, Ulrich Krohs, Marco Chittò, Diana Ferro, Kevin Ferro, Gildas Lepennetier, Hans-Dieter Görtz, Rebecca S Schreiber, Joachim Kurtz, Jürgen Gadau
Are we in the midst of a paradigm change in biology and have animals and plants lost their individuality, i.e., are even so-called 'typical' organisms no longer organisms in their own right? Is the study of the holobiont-host plus its symbiotic microorganisms-no longer optional, but rather an obligatory path that must be taken for a comprehensive understanding of the ecology and evolution of the individual components that make up a holobiont? Or are associated microbes merely a component of their host's environment, and the holobiont concept is just a beautiful idea that does not add much or anything to our understanding of evolution? This article explores different aspects of the concept of the holobiont...
December 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
K Argasinski, M Broom
In this paper we are concerned with how aggregated outcomes of individual behaviours, during interactions with other individuals (games) or with environmental factors, determine the vital rates constituting the growth rate of the population. This approach needs additional elements, namely the rates of event occurrence (interaction rates). Interaction rates describe the distribution of the interaction events in time, which seriously affects the population dynamics, as is shown in this paper. This leads to the model of a population of individuals playing different games, where focal game affected by the considered trait can be extracted from the general model, and the impact on the dynamics of other events (which is not neutral) can be described by an average background fertility and mortality...
November 20, 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Hervé Seligmann
Homology of some RNAs with template DNA requires systematic exchanges between nucleotides. Such exchanges produce 'swinger' RNA along 23 bijective transformations (nine symmetric, X ↔ Y; and 14 asymmetric, X → Y → Z → X, for example A ↔ C and A → C → G → A, respectively). Here, analyses compare amino acids coded by swinger-transformed codons to those coded by untransformed codons, defining coding invariance after transformations. Swinger transformations cluster according to coding invariance in four groups characterized by transformations into cytosine (C = C, T → C, A → C, and G → C)...
November 16, 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
Thomas Löser
A new system for maintaining homogeneous gene expression in tissue and for destroying through apoptosis nonconforming cells is introduced. This functionality is called the "similarity comparison." Accordingly, the survival of mutated cells is hindered due to reduced gene expression. That, in turn, maintains the homogeneity of the tissue and prevents tumors from developing. The concept of the similarity comparison is that every stationary cell in every tissue constantly screens the gene expression of its neighbors...
October 30, 2017: Theory in Biosciences, Theorie in Den Biowissenschaften
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