Must There Be a Balance of Nature?

The balance of nature concept is an old idea that manifests itself in anumber of forms in population and community ecology. This paper focuseson population ecology, where controversy surrounding the balance ofnature takes the form of perennial debates over the significance ofdensity dependence, population regulation, and species interactions suchas competition. One of the most striking features of these debates, overthe course of the previous century in ecology, is the tendency to arguethe case on largely conceptual grounds. This paper explores twoquestions. Why this tendency to settle on conceptual grounds what is soobviously an empirical issue? Are there any good conceptual arguments tobe had in this area?     

Evolution of insect-plant relationships — a devil's advocate approach

Most hypotheses concerning the evolution of insect-plant relationships are based on the assumptions that, (1) phytophagous insects reduce plant fitness, and that (2) insect-plant relationships are the result of unconstrained selection. It can be shown, however, that there is little evidence to support these assumptions. As an alternative, it is proposed that the evolution of insect-plant relationships results primarily from autonomous evolutionary events; namely from heritable functional changes within the insects' nervous system that determine plant recognition and ultimately host plant specificity. These changes cannot be evoked by selective ecological agents. They originate from intrinsic changes (mutationssensu lato) within the insect genome. Ecological factors play a secondary role: by either supporting or preventing the establishment of the new genotype with the novel food preference. This paper has been dedicated in warm friendship to Professor Louis M. Schoonhoven, the leading scientist in sensory physiology of phytophagous insects, on the occasion of his 60th birthday.     

Local-Scale Diversity and Between-Year “Frozen Evolution” of Avian Influenza A Viruses in Nature

Influenza A virus (IAV) in wild bird reservoir hosts is characterized by the perpetuation in a plethora of subtype and genotype constellations. Multiyear monitoring studies carried out during the last two decades worldwide have provided a large body of knowledge regarding the ecology of IAV in wild birds. Nevertheless, other issues of avian IAV evolution have not been fully elucidated, such as the complexity and dynamics of genetic interactions between the co-circulating IAV genomes taking place at a local-scale level or the phenomenon of frozen evolution. We investigated the IAV diversity in a mallard population residing in a single pond in the Czech Republic. Despite the relative small number of samples collected, remarkable heterogeneity was revealed with four different IAV subtype combinations, H6N2, H6N9, H11N2, and H11N9, and six genomic constellations in co-circulation. Moreover, the H6, H11, and N2 segments belonged to two distinguishable sub-lineages. A reconstruction of the pattern of genetic reassortment revealed direct parent-progeny relationships between the H6N2, H11N9 and H6N9 viruses. Interestingly the IAV, with the H6N9 subtype, was re-detected a year later in a genetically unchanged form in the close proximity of the original sampling locality. The almost absolute nucleotide sequence identity of all the respective genomic segments between the two H6N9 viruses indicates frozen evolution as a result of prolonged conservation in the environment. The persistence of the H6N9 IAV in various abiotic and biotic environmental components was also discussed.     

The Soft Underbelly of Evolution?

Evolution and the origin of life are separate, if connected, topics, but they are frequently conflated??especially by creationists. Regarding the natural origin of life as ??the soft underbelly?? of evolution, creationists argue that it is impossible, improbable, or insusceptible to scientific investigation. Underlying their arguments is the hope that the failure of scientific research on the origin of life is evidence for a supernatural account. It is crucial for teachers to understand the nature of science in order to be able to explain why appeals to the supernatural are out of place in explaining the origin of life and why scientific research on the origin of life is not intrinsically a threat to faith.     

The Emergence and Evolution of Life in a “Fatty Acid World” Based on Quantum Mechanics

Quantum mechanical based electron correlation interactions among molecules are the source of the weak hydrogen and Van der Waals bonds that are critical to the self-assembly of artificial fatty acid micelles. Life on Earth or elsewhere could have emerged in the form of self-reproducing photoactive fatty acid micelles, which gradually evolved into nucleotide-containing micelles due to the enhanced ability of nucleotide-coupled sensitizer molecules to absorb visible light. Comparison of the calculated absorption spectra of micelles with and without nucleotides confirmed this idea and supports the idea of the emergence and evolution of nucleotides in minimal cells of a so-called Fatty Acid World. Furthermore, the nucleotide-caused wavelength shift and broadening of the absorption pattern potentially gives these molecules an additional valuable role, other than a purely genetic one in the early stages of the development of life. From the information theory point of view, the nucleotide sequences in such micelles carry positional information providing better electron transport along the nucleotide-sensitizer chain and, in addition, providing complimentary copies of that information for the next generation. Nucleotide sequences, which in the first period of evolution of fatty acid molecules were useful just for better absorbance of the light in the longer wavelength region, later in the PNA or RNA World, took on the role of genetic information storage.     

The Origin of Life: Chemical Evolution of a Metabolic System in a Mineral Honeycomb?

For the RNA-world hypothesis to be ecologically feasible, selection mechanisms acting on replicator communities need to be invoked and the corresponding scenarios of molecular evolution specified. Complementing our previous models of chemical evolution on mineral surfaces, in which selection was the consequence of the limited mobility of macromolecules attached to the surface, here we offer an alternative realization of prebiotic group-level selection: the physical encapsulation of local replicator communities into the pores of the mineral substrate. Based on cellular automaton simulations we argue that the effect of group selection in a mineral honeycomb could have been efficient enough to keep prebiotic ribozymes of different specificities and replication rates coexistent, and their metabolic cooperation protected from extensive molecular parasitism. We suggest that mutants of the mild parasites persistent in the metabolic system can acquire useful functions such as replicase activity or the production of membrane components, thus opening the way for the evolution of the first autonomous protocells on Earth.     

Evolution of the “autophagamiR”

MicroRNAs (miRs) are increasingly important diagnostic and prognostic markers in cancer but have not been defined in medullary thyroid carcinoma (MTC). MiR microarray profiling was performed on 19 primary MTC tumors, validated with qPCR in 45 cases and correlated with clinical outcomes. MiRs-183 and 375 were overexpressed and miR-9* underexpressed in sporadic vs. hereditary MTC (SMTC; HMTC). MiR-183 and 375 overexpression predicted lateral nodal metastases, residual disease, distant metastases and mortality. MiR-183 knockdown in an MTC cell line (TT cells) reduced cellular proliferation in association with elevated LC3B expression. This is suggestive of increased autophagic flux and potential cell death via autophagy induction. MiRs may subsequently be shown to serve as efficacious therapeutic strategies in MTC with a mechanism based upon autophagy.     

The Rate of Human Germline Mutations—Variable Factor of Evolution and Diseases

Russian Journal of Genetics - The emergence of genetic diseases and evolutionary processes are associated with the flow of genetic information from one generation to another, in which genetic...     

Nature of plasmalemmal functional “hemichannels”

The molecular identity of the protein forming “hemichannels” at non-junctional membranes is disputed. The family of gap junction proteins, innexins, connexins, and pannexins share several common features, including permeability characteristics and sensitivity to blocking agents. Such overlap in properties renders the identification of which of these protein species actually establishes the non-junctional membrane conductance and permeability quite complicated, especially because in vertebrates pannexins and connexins have largely overlapping distributions in tissues. Recently, attempts to establish criteria to identify events that are “hemichannel” mediated and those to allow the distinction between connexin- from pannexin-mediated events have been proposed.Here, I present an update on that topic and discuss the most recent findings related to the nature of functional “hemichannels” focusing on connexin43 and pannexin1. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.