Schistosoma mansoni is one of several species of trematode helminths responsible for schistosomiasis, a major parasitic infection of man. Genetic analysis in mice has revealed that the protective immunity induced against this parasite by an attenuated larval vaccine is strongly influenced by genes regulating the activation of macrophage effector cells. The latter finding suggests that the induction of cell‐mediated immunity may be a successful strategy for a non‐living vaccine against the human infection.

Many of the most virulent and problematic eukaryotic pathogens have evolved from photosynthetic ancestors, such as apicomplexans, which are responsible for a wide range of diseases including malaria and toxoplasmosis. The primary barrier to understanding the early stages of evolution of these parasites has been the difficulty in finding parasites with closely related free‐living lineages with which to make comparisons. Parasites found throughout the florideophyte red algal lineage, however, provide a unique and powerful model to investigate the (...) genetic origins of a parasitic lifestyle. This is because they share a recent common ancestor with an extant free‐living red algal species and parasitism has independently arisen over 100 times within this group. Here, we synthesize the relevant hypotheses with respect to how these parasites have proliferated. We also place red algal research in the context of recent developments in understanding the genome evolution of other eukaryotic photosynthesizers turned parasites. (shrink)

It has recently emerged that malarial, toxoplasmodial and related parasites contain a vestigial plastid (the organelle in which photosynthesis occurs in plants and algae). The function of the plastid in these obligate intracellular parasites has not been established. It seems likely that modern apicomplexans derive from photosynthetic predecessors, which perhaps formed associations with protists and invertebrates and abandoned autotrophy in favour of parasitism. Recognition of a third genetic compartment in these parasites proffers alternative strategies for combating (...) a host of important human and animal diseases. It also poses some fascinating questions about the evolutionary biology of this important group of pathogens. (shrink)

At least four conceptually distinct mechanisms may mediate relations between parasite-stress and cultural outcomes: genetic evolution, developmental plasticity, neurocognitive flexibility, and cultural transmission. These mechanisms may operate independently or in conjunction with one another. Rigorous research on specific mediating mechanisms is required to more completely articulate implications of parasite stress on human psychology and human culture.

Viruses and related infectious genetic parasites are the most abundant biological agents on this planet. They invade all cellular organisms, are key agents in the generation of adaptive and innate immune systems, and drive nearly all regulatory processes within living cells.

The language parasite approach refers to the view that language, like a parasite, is an adaptive system that evolves to fit its human hosts. Supported by recent computer simulations, LPA proponents claim that the reason that humans can use languages with ease is not because we have evolved with genetically specified linguistic instincts but because languages have adapted to the preexisting brain structures of humans. This article examines the LPA. It argues that, while the LPA has advantages over its rival, (...) Chomskyan nativism, there are additional factors that may limit linguistic variety that have yet to be identified by its insightful proponents. This article suggests abandoning the search for a decisive cause of language capacity and argues that language evolution is more likely to arise from balancing multiple engineering constraints. (shrink)

New data of recent researches on genetics and epidemiology imply the idea of rapidly evolving viruses through DNA recombination, which leads to the establishment of new virus families, eventually adapted to the environmental conditions. Consequently the framework of the epidemiological studies widens, replacing the classic aspect of the bilateral virus—host coexistence.An holistic evolutionary approach, considering all the complex interrelationship among viruses, parasites and hosts, in conjugation with the environmental changes is developing.Molecular epidemiology and updated population models renew the health (...) strategy bringing together experts from the fields of population biology, evolution and infectious diseases.The related ethical issues, which consequently emerge should be faced accordingly. (shrink)

We address the controversy in the literature concerning the definition of holobionts and the apparent constraints on their evolution using concepts from community population genetics. The genetics of holobionts, consisting of a host and diverse microbial symbionts, has been neglected in many discussions of the topic, and, where it has been discussed, a gene-centric, species-centric view, based in genomic conflict, has been predominant. Because coevolution takes place between traits or genes in two or more species and not, strictly speaking, between (...) species, it may affect some traits but not others in either host or symbiont. Moreover, when interacting species pairs are embedded in a larger community, indirect ecological effects can alter the expected pairwise dynamics. Mode of symbiont transmission and the degree of host inbreeding both affect the extent of microbial mixing across host lineages and thereby the degree to which selection on one trait of either partner affects other aspects of a holobiont phenotype. We discuss several potential defining criteria for holobionts using community genetics and population genetics models, suggesting their application and limitations. Using community genetics models, we show how conflict between genomes can be self-limiting, while cooperation and mutualism tend to be self-accelerating. It is likely that this bias in the evolutionary dynamics of interaction between hosts and symbionts is an important feature of holobionts. This bias in the evolutionary dynamic could contribute to explaining the absence of cheaters from natural mutualisms, although cheaters are predicted by gene-centered conflict theory to cause the evolutionary instability of mutualisms. Additionally, it may help explain the more frequent origin of mutualisms from parasitic than from free-living systems, an evolutionary trajectory opposite to that predicted by genome conflict theory. (shrink)

Mitochondrial genomes are clearly marked by a strong tendency towards reductive evolution. This tendency has been facilitated by the transfer of most of the essential genes for mitochondrial propogation and function to the nuclear genome. The most extreme examples of genomic simplification are seen in animal mitochondria, where there also are the greatest tendencies to codon reassignment. The reassignment of codons to amino acids different from those designated in the so called universal code is seen in part as an expression (...) of the reduction of the number of genes used by these genomes to code for tRNA species. The driving force for the reductive evolution of mitochondrial genomes is identifed with two population genetic effects which may also be operating on populations of parasites. (shrink)

The biogenesis of RNAs and proteins is a threat to the cell. Indeed, the act of transcription and nascent RNAs challenge DNA stability. Both RNAs and nascent proteins can also initiate the formation of toxic aggregates because of their physicochemical properties. In reviewing the literature, I show that co-transcriptional and co-translational biophysical constraints can trigger DNA instability that in turn increases the likelihood that sequences that alleviate the constraints emerge over evolutionary time. These directed genetic variations rely on the (...) biogenesis of small RNAs that are transcribed directly from challenged DNA regions or processed from the transcripts that directly or indirectly generate constraints or aggregates. These small RNAs can then target the genomic regions from which they initially originate and increase the local mutation rate of the targeted loci. This mechanism is based on molecular pathways involved in anti-parasite genome defence systems, and implies that gene expression-related biophysical constraints represent a driving force of genome evolution. Are randomly generated mutations the only source of genetic variation during evolution? This paper describes the molecular mechanisms by which co-transcriptional and co-translational biophysical constraints trigger genetic variations in targeted-genomic sequences in an RNA-depending manner. This directed-mutational process that drives genome evolution is related to antiparasite genome defence systems. (shrink)

Leishmania major infection of inbred mice leads to a major dichotomous response—death or survival—that depends on the strain of mice. This finding has motivated efforts to locate genetic determinants of disease susceptibility. Genotyping studies have confirmed a complex multilocus trait, but studies directed at the biology of the response suggest identifiable components of susceptibility that may direct the genetic investigations. A confluence of parasite variables—residence in macrophages, class II-dependent immunity, and avoidance of early IL-12 induction—with host factors—a prominent (...) helper T-cell precursor frequency to a dominant parasite epitope and a bias in IL-4 gene activation—conspires to drive an aberrant immune response in animals that suffer fatal disease. These insights may lead to an understanding of factors that focus responses on dominant antigens and that mold the naive T-cell repertoire. Collectively, such factors might contribute to the pathogenesis of other infectious and autoimmune diseases. BioEssays 21:510–518, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

I investigate how theoretical assumptions, pertinent to different perspectives and operative during the modeling process, are central in determining how nature is actually taken to be. I explore two different models by Michael Turelli and Steve Frank of the evolution of parasite-mediated cytoplasmic incompatility, guided, respectively, by Fisherian and Wrightian perspectives. Since the two models can be shown to be commensurable both with respect to mathematics and data, I argue that the differences between them in the (1) mathematical presentation of (...) the models, (2) explanations, and (3) objectified ontologies stem neither from differences in mathematical method nor the employed data, but from differences in the theoretical assumptions, especially regarding ontology, already present in the respective perspectives. I use my "set up, mathematically manipulate, explain, and objectify" (SMEO) account of the modeling process to track the model-mediated imposition of theoretical assumptions. I conclude with a discussion of the general implications of my analysis of these models for the controversy between Fisherian and Wrightian perspectives. (shrink)

All the conserved detailed results of evolution stored in DNA must be read, transcribed, and translated via an RNAmediated process. This is required for the development and growth of each individual cell. Thus, all known living organisms fundamentally depend on these RNA-mediated processes. In most cases, they are interconnected with other RNAs and their associated protein complexes and function in a strictly coordinated hierarchy of temporal and spatial steps (i.e., an RNA network). Clearly, all cellular life as we know it (...) could not function without these key agents of DNA replication, namely rRNA, tRNA, and mRNA. Thus, any definition of life that lacks RNA functions and their networks misses an essential requirement for RNA agents that inherently regulate and coordinate (communicate to) cells, tissues, organs, and organisms. The precellular evolution of RNAs occurred at the core of the emergence of cellular life and the question remained of how both precellular and cellular levels are interconnected historically and functionally. RNA-networks andRNA-communication can interconnect these levels.With the reemergence of virology in evolution, it became clear that communicating viruses and subviral infectious genetic parasites are bridging these two levels by invading, integrating, coadapting, exapting, and recombining constituent parts in host genomes for cellular requirements in gene regulation and coordination aims. Therefore, a 21st century understanding of life is of an inherently social process based on communicating RNA networks, in which viruses and cells continuously interact. (shrink)

The study of alternative genetic systems and mixed modes of reproduction, whereby sexual and asexual reproduction is combined within the same lifecycle, is of fundamental importance as they may shed light on classical evolutionary issues, such as the paradox of sex. Recently, several such cases were discovered in social insects. A closer examination of these systems has revealed many amazing facts, including the mixed use of asexual and sexual reproduction for the production of new queens and workers, males that (...) can clone themselves and the routine use of incest without deleterious genetic consequences. In addition, in several species, remarkable cases of asexually reproducing socially parasitic worker lineages have been discovered. The study of these unusual systems promises to provide insight into many basic evolutionary questions, including the maintenance of sex, the expression of sexual conflict and kin conflict and the evolution of cheating in asexual lineages. (shrink)

Although natural selection might be expected to reduce the incidence and severity of disease, disease persists. Natural selection leads to increases in the mean fitness of populations and so will reduce the frequency of disease-associated alleles, but other evolutionary processes, such as mutation and gene flow, may introduce or increase the frequency of these deleterious alleles. The pleiotropic actions of genes and the epistatic interactions between them complicate the relationship between genotype and phenotype, and may result in the preservation of (...) disease-associated alleles. Deleterious alleles may also be maintained because of linkage to beneficial alleles. The inability of natural selection to eliminate diseases of aging is a reminder that fitness – success in producing progeny, or in contributing genes to the population gene pool – is not equivalent to the absence of disease. Nutritional or psychosocial cues may lead to life history strategies that maximize survival to reproductive maturity at the expense of disease later in life. Natural selection acts on genes, cells, and groups, as well as on organisms; the outcome of evolution reflects selection at different levels of biological organization. Finally, the human environment is constantly changing, largely because of the evolution of our parasites and because of changes in cultural beliefs and practices; genetic evolution is comparatively slow and lags behind environmental change. An evolutionary nosology complements traditional medical nosologies and enhances our understanding of the persistence of disease and the meaning of human variation. (shrink)

We suggest that supergenes, groups of co‐inherited loci, may be involved in a range of intriguing genetic and evolutionary phenomena in insect societies, and may play broad roles in the evolution of cooperation and conflict. Supergenes are central in the evolution of an array of traits including self‐incompatibility, mimicry, and sex chromosomes. Recently, researchers identified a large supergene, described as a social chromosome, which controls social organization in the fire ant. This system was previously considered to be a remarkable (...) example of a single gene affecting a complex social trait. We describe how selection may commonly favor reduced recombination and the formation of supergenes for social traits, and once formed, supergenes may strongly influence further evolutionary dynamics within and between lineages. The evolution of supergenes, and even wholly non‐recombining genomes, may be particularly common in systems in which genetically distinct lineages can form mutually reinforcing socially parasitic relationships. (shrink)

Communication is defined as an interaction between at least two living agents which share a repertoire of signs. These are combined according to syntactic, semantic and context dependent, pragmatic rules in order to coordinate behavior. This volume deals with the important roles of soil bacteria in parasitic and symbiotic interactions with viruses, plants, animals and fungi. Starting with a general overview of the key levels of communication between bacteria, further reviews examine the various aspects of intracellular as well as intercellular (...) biocommunication between soil microorganisms. Th is includes the various levels of biocommunication between phages and bacteria, between soil algae and bacteria, and between bacteria, fungi and plants in the rhizosphere, the role of plasmids and transposons, horizontal gene transfer, quorum sensing and quorum quenching, bacterial-host cohabitation, phage-mediated genetic exchange and soil viral ecology. (shrink)

Germ cell segregation and gamete production are developmental problems that all sexually reproducing species must solve in order to survive. Many people are familiar with the complex social structures of some insect species, where specialised castes of adult insects perform specific tasks, one of which is usually to guard the sexually reproductive queen. The parasitic wasp Copidosoma floridanum adds another level of complexity to the caste system: a fertilised egg produces both sterile, short‐lived “soldier” larvae and “reproductive” larvae that complete (...) metamorphosis to produce sexually reproductive adults. How two morphologically and functionally distinct larval castes are produced by genetically identical groups of cells developing under the same environmental conditions is a baffling problem. A recent paper suggests that differential germ cell segregation during embryogenesis may be an event both necessary and sufficient for caste determination.1 BioEssays 26:1263–1267, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

In spite of advances in medicine and public health, malaria and other mosquito‐borne diseases are on the rise worldwide. Although vaccines, genetically modified mosquitoes and safer insecticides are under development, herein we examine a promising new approach to malaria control through better repellents. Current repellents, usually based on DEET, inhibit host finding by impeding insect olfaction, but have significant drawbacks. We discuss how comparative genomics, using data from the Anopheles genome project, allows the rapid identification of members of three protein (...) classes critical to insect olfaction: odorant‐binding proteins, G‐protein‐coupled receptors, and odorant‐degrading enzymes. A rational design approach similar to that used by the pharmaceutical industry for drug development can then be applied to the development of products that interfere with mosquito olfaction. Such products have the potential to provide more complete, safer and longer lasting protection than conventional repellents, preventing disease transmission by interrupting the parasite life cycle. BioEssays 25:1011–1020, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

The P family of transposable genetic elements is thought to be a recent addition to the Drosophila melanogaster genome. New evidence suggests that the elements came from another Drosophila species, possibly carried by parasitic mites. The transposition mechanism of P elements involves DNA gap repair which may have facilitated their rapid spread through D. melanogaster worldwide. These results provide new insight into the process of a transpo‐son's invasion into a new species and the potential risk of extinction such an (...) invasion might entail. (shrink)

Each year, over 200 million people are infected with the malaria parasite, nearly half a million of whom succumb to the disease. Emerging genetic technologies could, in theory, eliminate the burden of malaria throughout the world by intentionally eradicating the mosquitoes that transmit the disease. In this paper, we offer an ethical examination of the intentional eradication of Anopheles gambiae, the main malaria vector of sub-Saharan Africa. In our evaluation, we focus on two main considerations: the benefit of alleviating (...) the malaria burden, and the loss of value that would accompany the eradication of the species. We outline a typology of the different ways in which species are valued or could be valuable, then use that typology to appraise the value of the species in question. We argue that Anopheles gambiae has minor (and redundant) instrumental value, little final subjective value and no objective final value. (shrink)

The CRISPR-Cas systems of bacterial and archaeal adaptive immunity have become a household name among biologists and even the general public thanks to the unprecedented success of the new generation of genome editing tools utilizing Cas proteins. However, the fundamental biological features of CRISPR-Cas are of no lesser interest and have major impacts on our understanding of the evolution of antivirus defense, host-parasite coevolution, self versus non-self discrimination and mechanisms of adaptation. CRISPR-Cas systems present the best known case in point (...) for Lamarckian evolution, i.e. generation of heritable, adaptive genomic changes in response to encounters with external factors, in this case, foreign nucleic acids. CRISPR-Cas systems employ multiple mechanisms of self versus non-self discrimination but, as is the case with immune systems in general, are nevertheless costly because autoimmunity cannot be eliminated completely. In addition to the autoimmunity, the fitness cost of CRISPR-Cas systems appears to be determined by their inhibitory effect on horizontal gene transfer, curtailing evolutionary innovation. Hence the dynamic evolution of CRISPR-Cas loci that are frequently lost and acquired by archaea and bacteria. Another fundamental biological feature of CRISPR-Cas is its intimate connection with programmed cell death and dormancy induction in microbes. In this and, possibly, other immune systems, active immune response appears to be coupled to a different form of defense, namely, “altruistic” shutdown of cellular functions resulting in protection of neighboring cells. Finally, analysis of the evolutionary connections of Cas proteins reveals multiple contributions of mobile genetic elements to the origin of various components of CRISPR-Cas systems, furthermore, different biological systems that function by genome manipulation appear to have evolved convergently from unrelated MGE. The shared features of adaptive defense systems and MGE, namely the ability to recognize and cleave unique sites in genomes, make them ideal candidates for genome editing and engineering tools. (shrink)

A common belief is that evolution generally proceeds towards greater complexity at both the organismal and the genomic level, numerous examples of reductive evolution of parasites and symbionts notwithstanding. However, recent evolutionary reconstructions challenge this notion. Two notable examples are the reconstruction of the complex archaeal ancestor and the intron‐rich ancestor of eukaryotes. In both cases, evolution in most of the lineages was apparently dominated by extensive loss of genes and introns, respectively. These and many other cases of reductive (...) evolution are consistent with a general model composed of two distinct evolutionary phases: the short, explosive, innovation phase that leads to an abrupt increase in genome complexity, followed by a much longer reductive phase, which encompasses either a neutral ratchet of genetic material loss or adaptive genome streamlining. Quantitatively, the evolution of genomes appears to be dominated by reduction and simplification, punctuated by episodes of complexification. (shrink)

Whenever the state of a biological system is not determined solely by present conditions but depends on its past history, we can say that the system has memory. Bacteria and bacteriophage use a variety of memory mechanisms, some of which seem to convey adaptive value. A genetic type of heritable memory is the programmed inversion of specific DNA sequences, which causes switching between alternative patterns of gene expression. Heritable memory can also be based on epigenetic circuits, in which a (...) system with two possible steady states is locked in one or the other state by a positive feedback loop. Epigenetic states have been observed in a variety of cellular processes, and are maintained by diverse mechanisms. Some of these involve alternative DNA methylation patterns that are stably transmitted to daughter molecules and can affect DNA–protein interactions (e.g., gene transcription). Other mechanisms exploit autocatalytic loops whereby proteins establish the proper conditions for their continued synthesis. Template polymers other than nucleic acids (e.g., components of the cell wall) may also propagate epigenetic states. Non‐heritable memory is exemplified by parasitic organisms that bear a signature of their previous host, such as host‐controlled modification of phage DNA or porin hitchhiking in predatory bacteria. The heterogeneous nature of the examples known may be indicative of widespread occurrence of memory mechanisms in bacteria and phage. However, the actual extent, variety and potential selective value of prokaryotic memory devices remain open questions, still to be addressed experimentally. BioEssays 24:512–518, 2002. © 2002 Wiley Periodicals, Inc. (shrink)

Frederick Griffith was an English bacteriologist at the Pathological Laboratory of the Ministry of Health in London who believed that progress in the epidemiology and control of infectious diseases would come only with more precise knowledge of the identity of the causative microorganisms. Over the years, Griffith developed and expanded a serological technique for identifying pathogenic microorganisms, which allowed the tracing of the sources of infectious disease outbreaks: slide agglutination. Yet Griffith is not remembered for his contributions to the biology (...) and epidemiology of infectious diseases so much as for discovering the phenomenon known as ‘transformation’. Griffith’s discovery, for many, was a pure case of serendipity whose biological relevance had also largely escaped him. In this paper, I argue that the key to understanding the significance of bacterial transformation – and the scientific legacy of Fred Griffith – rests not only on it initiating a cascade of events leading to molecular genetics but also on its implications for epidemiology based on the biology of host–parasite interactions. Looking at Griffith’s entire career, instead of focusing only on the transformation study, we can better appreciate the place of the latter within Griffith’s overall contributions. Presented in this way, Griffith’s experiment on bacterial transformation also ceases to appear as an anomaly, which in turn leads us to rethink some of the most prevalent historical conceptions about his work. (shrink)

In searching for life in extraterrestrial space, it is essential to act based on an unequivocal definition of life. In the twentieth century, life was defined as cells that self-replicate, metabolize, and are open for mutations, without which genetic information would remain unchangeable, and evolution would be impossible. Current definitions of life derive from statistical mechanics, physics, and chemistry of the twentieth century in which life is considered to function machine like, ignoring a central role of communication. Recent observations (...) show that context-dependent meaningful communication and network formation (and control) are central to all life forms. Evolutionary relevant new nucleotide sequences now appear to have originated from social agents such as viruses, their parasitic relatives, and related RNA networks, not from errors. By applying the known features of natural languages and communication, a new twenty-first century definition of life can be reached in which communicative interactions are central to all processes of life. A new definition of life must integrate the current empirical knowledge about interactions between cells, viruses, and RNA networks to provide a better explanatory power than the twentieth century narrative. (shrink)

This essay considers biotrophic cyst and root‐knot nematodes in relation to their biology, host–parasite interactions and molecular genetics. These nematodes have to face the biological consequences of the physical constraints imposed by the soil environment in which they live while their hosts inhabit both above and below ground environments. The two groups of nematodes appear to have adopted radically different solutions to these problems with the result that one group is a host specialist and reproduces sexually while the other has (...) an enormous host range and reproduces by mitotic parthenogenesis. We consider what is known about the modes of parasitism used by these nematodes and how it relates to their host range, including the surprising finding that parasitism genes in both nematode groups have been recruited from bacteria. The nuclear and mitochondrial genomes of these two nematode groups are very different and we consider how these findings relate to the biology of the organisms. BioEssays 30:249–259, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Evolutionary socioecological theory and research proposing linking parasites with human social organization is uncommon and therefore welcome. However, more generally, condition-dependent adaptive phenotypic plasticity requires environmental uncertainty on a small scale, accompanied by reliable cues. In addition, genes in parasites may select among biologically adaptive cultural alternatives directly without necessarily going through human genetic predispositions, resulting in inter-specific gene-culture coevolution.

This essay examines the public debate about the agricultural biotechnologies known as genetically modified organisms, as that debate is being carried out in its most dichotomizing forms in the United States. It attempts to reveal the power of sharply dichotomous thinking, as well as its limits. The essay draws on the work of Michel Serres, who uses the concept of the parasite to reconstruct or reframe fundamental dichotomies in western philosophy; it attempts a similar reframing of the public debates about (...) GMOs. The purpose of such a reframing is to create possibilities for dialogue among participants that will move beyond the polarization that characterizes much of the current debate in the U.S. (shrink)

Communication is defined as an interaction between at least two living agents which share a repertoire of signs. These are combined according to syntactic, semantic and context-dependent, pragmatic rules in order to coordinate behavior. This volume deals with the important roles of soil bacteria in parasitic and symbiotic interactions with viruses, plants, animals and fungi. Starting with a general overview of the key levels of communication between bacteria, further reviews examine the various aspects of intracellular as well as intercellular biocommunication (...) between soil microorganisms. This includes the various levels of biocommunication between phages and bacteria, between soil algae and bacteria, and between bacteria, fungi and plants in the rhizosphere, the role of plasmids and transposons, horizontal gene transfer, quorum sensing and quorum quenching, bacterial-host cohabitation, phage-mediated genetic exchange and soil viral ecology. (shrink)

An interpretive system for the IBM 704 computer permitting interpretation of the genetic pattern of a numeric symbioorganism as a game strategy has been developed. Selection for best performance in a simple game has been applied in a preliminary experiment. An objective method to measure the quality of a game played is described. The results presented in the article show a small but significant improvement of game quality during a period of 2300 generations.The general characteristics of the phenomena observed (...) are similar to those of preceding evolution experiments . However, a startling infection process caused by a parasite whose behaviour was influenced by the game competition is described. The parasite never developed an independent game strategy to any degree of efficiency and was entirely dependent on its host organism for game competitions with, and transmission of the infection to, uninfected hosts.The consequences of substituting the reproduction and mutation rules used in the preceding evolution experiments are discussed. Particularly, the use of rules applying the reproduction pattern ofDNA-molecules is considered, and the theoretic aspects of symbiogenetic evolution experiments based onDNA-norm are discussed. A few inferences concerning the origin and history of terrestrial life suggested by the results of the symbiogenesis experiments are presented.Ein interpretierendes System für die IBM 704 Rechenmaschine, dass Interpretation des genetischen Modells von einem numerischen Symbio-organismus wie eine Spiel Strategie, erlaubt, wurde entwickelt. Eine Forführung für Fähigkeit in einem einfachen Spiel wurde angewandt in einem preliminarisches Experiment. Eine objektive Methode zur Messung der Qualität des betreffenden Spiels wurde beschrieben. Die in dem Artikel angegebenen Resultate zeigen eine kleine, aber bedeutende Verbesserung der Spiel-Qualität während einr Periode von 2300 Generationen.Die allgemeinen Kennziechen von den beobachteten Phänomenen sind denen von vorhergehenden Evolutions-Experimenten ähnlich . Jedoch, ein überraschender Infektions-Prozess, verursacht durch einen Parasit, wessen Verhalten beinflusst wurde durch die Spiel-Konkurrenz, wurde beschrieben. Der Parasit entwickelte niemals eine unabhängige Spiel-Strategie zu irgendeinem Masze von Fähigkeit und war ganz abhängig von seinem Gastherr-Organismus für Spiel-Konkurrenz mit, und Überbringung von der Infektion auf, uninfektierte Gäste.Die Folgerungen von dem Ersetzen der Fortpflanzung und Mutations-Regeln , angewandt in vorhergehenden Evolutions-Experimente wurden besprochen. Besonders der Gebrauch von Regeln welche das FortpflanzungsModell von DNA-Molekülen anwenden wurde betrachtet, und die theorethischen Aspekte von Symbiogenetischen Evolutions-Experimenten basiert auf DNA-Norm wurden besprochen. Einige Schlussfolgerungen in Bezug auf die Entstehung und Geschichte von dem Erdenleben suggeriert durch die Resultate von den Symbiogenese-Experimenten wurden gezeigt. (shrink)

This essay examines the public debate about the agricultural biotechnologies known as genetically modified organisms, as that debate is being carried out in its most dichotomizing forms in the United States. It attempts to reveal the power of sharply dichotomous thinking, as well as its limits. The essay draws on the work of Michel Serres, who uses the concept of the parasite to reconstruct or reframe fundamental dichotomies in western philosophy; it attempts a similar reframing of the public debates about (...) GMOs. The purpose of such a reframing is to create possibilities for dialogue among participants that will move beyond the polarization that characterizes much of the current debate in the U.S. (shrink)

The CRISPR-Cas systems of bacterial and archaeal adaptive immunity have become a household name among biologists and even the general public thanks to the unprecedented success of the new generation of genome editing tools utilizing Cas proteins. However, the fundamental biological features of CRISPR-Cas are of no lesser interest and have major impacts on our understanding of the evolution of antivirus defense, host-parasite coevolution, self versus non-self discrimination and mechanisms of adaptation. CRISPR-Cas systems present the best known case in point (...) for Lamarckian evolution, i.e. generation of heritable, adaptive genomic changes in response to encounters with external factors, in this case, foreign nucleic acids. CRISPR-Cas systems employ multiple mechanisms of self versus non-self discrimination but, as is the case with immune systems in general, are nevertheless costly because autoimmunity cannot be eliminated completely. In addition to the autoimmunity, the fitness cost of CRISPR-Cas systems appears to be determined by their inhibitory effect on horizontal gene transfer, curtailing evolutionary innovation. Hence the dynamic evolution of CRISPR-Cas loci that are frequently lost and acquired by archaea and bacteria. Another fundamental biological feature of CRISPR-Cas is its intimate connection with programmed cell death and dormancy induction in microbes. In this and, possibly, other immune systems, active immune response appears to be coupled to a different form of defense, namely, “altruistic” shutdown of cellular functions resulting in protection of neighboring cells. Finally, analysis of the evolutionary connections of Cas proteins reveals multiple contributions of mobile genetic elements to the origin of various components of CRISPR-Cas systems, furthermore, different biological systems that function by genome manipulation appear to have evolved convergently from unrelated MGE. The shared features of adaptive defense systems and MGE, namely the ability to recognize and cleave unique sites in genomes, make them ideal candidates for genome editing and engineering tools. (shrink)

Cas9/guide RNA (gRNA)‐based gene drive systems are expected to play a transformative role in malaria elimination efforts., whether through population modification, in which the drive system contains parasite‐refractory genes, or population suppression, in which the drive system induces a severe fitness load resulting in population decline or extinction. DNA sequence polymorphisms representing alternate alleles at gRNA target sites may confer a drive‐resistant phenotype in individuals carrying them. Modeling predicts that, for observed levels of SGV at potential target sites and observed (...) rates of de novo DRA formation, population modification strategies are uniquely resilient to DRAs. We conclude that gene drives can succeed when fitness costs incurred by drive‐carrying mosquitoes are low enough to prevent strong positive selection for DRAs produced de novo or as part of the SGV and that population modification strategies are less prone to failure due to drive resistance. (shrink)

Society has historically not taken a benign view of genetic disease. The laws permitting sterilization of the mentally re tarded~ and those proscribing consanguineous marriages are but two examples. Indeed as far back as the 5th-10th centuries, B.C.E., consanguineous unions were outlawed (Leviticus XVIII, 6). Case law has traditionally tended toward the conservative. It is reactive rather than directive, exerting its influence only after an individual or group has sustained injury and brought suit. In contrast, state legislatures have not (...) been inhibited in enacting statutes. Many of their products can be characterized as hasty, unnecessary, ill-conceived, and based on the heart rather than the head. Moreover the lack of expert consultation sought has also been remarkable. One state legislature, for example, has advocated immunization for sickle cell anemia! Many others have enacted laws for the screening of inborn errors of metabolism, e.g., phenylketon uria, but have poorly defined the lines of responsibility to secure compliance. A spate of specific disease-related bills has emerged in the u.S. Congress, each seeking recognition and appropriations. Sickle cell anemia, hemophilia, Cooley's anemia and Tay-Sachs disease have been among the front-runners for support. Finally, in 1975, Congress has begun to examine an omnibus bill concerning all forms of genetic disease. The bill, termed the National Genetic Diseases Act is, however, still far from being enacted. (shrink)

Signs and States, programme financé par l'ERG (European Research Council), a pour but d'explorer la sémiologie de l'Etat du XIIIe siècle au milieu du XVIIe siècle. Textes, performances, images, liturgies, sons et musiques, architectures, structures spatiales, tout ce qui contribue à la communication des sociétés politiques, tout ce qu'exprime l'idéel des individus et leur imaginaire, est ici passé au crible dans trois séries de rencontres dont les actes ont été rassemblés dans une collection, Le pouvoir symbolique en Occident (1300-1640). Ces (...) volumes, adoptant une perspective pluridisciplinaire et comparative dans une visée de long terme, combinent études de cas, analyses conceptuelles et réflexions plus théoriques. Et les réponses à ce questionnaire, issu d'une réflexion sur une histoire culturelle poursuivie sur plus de cinq siècles, remettent en cause une histoire de l'Occident latin où l'on opposerait Eglise et Etat : la mutation culturelle engendrée par la réforme grégorienne qui, tout en assurant d'abord le triomphe de la papauté, a donné à l'Etat moderne les moyens d'assurer sa propre légitimité en créant les conditions d'une révolution du système de communication. Elle engendre un partage du pouvoir symbolique et des processus de légitimation avec l'Etat : la capacité de ce dernier à se légitimer par le consentement de la société politique en dehors de la contingence religieuse est une spécificité de l'Occident latin, clé de l'essor des Etats modernes européens. (shrink)

The Epic of Evolution is a course taught at Northern Arizona University. It engages the task of formulating a new epic myth that is based on the physical, natural, social, and cultural sciences. It aims to serve the need of providing meaning for human living in the vast and complex universe that the sciences now depict for us. It is an interdisciplinary effort in an academic setting that is often divided by specializations; it focuses on values in a climate of (...) relativism; and it concentrates on an enterprise for which there are few textbooks at hand. The course is presented in three segments: the cosmos before humans appeared, the human phenomenon, and scenarios for the future of evolution. (shrink)

The role of fixed charges present at the surface of biological membranes is usually described by the Gouy-Chapman-Grahame theory of the electric double-layer where the Grahame equation is applied independently on each side of the membrane and where the capacitive charges are disregarded. In this article, we generalize the Gouy-Chapman-Grahame theory by taking into account both intrinsic charges and capacitive charges, in the density value of the membrane surface charges. In the first part, we show that capacitive charges couple electrostatic (...) potentials present on both sides of the membrane. The intensity of this coupling depends both on the value of the membrane specific capacitance and the transmembrane electric potential difference. In the second part, we suggest some physiological implications of membrane electric double-layers. (shrink)

The rapidly changing field of genetics affects society through advances in health-care and through implications of genetic research. This study addresses the impacts of new genetic discoveries and technologies on different segments of today's society. The book begins with a chapter on genetic complexity, and subsequent chapters discuss moral and ethical questions arising from today's genetics from the perspectives of health care professionals, the media, the general public, special interest groups and commercial interests.