We provide an introduction to network theory, evidence to support a connection between molecular network structure and neuropsychiatric disease, and examples of how network approaches can expand our knowledge of the molecular bases of these diseases. Without systematic methods to derive their biological meanings and inter‐relatedness, the many molecular changes associated with neuropsychiatric disease, including genetic variants, gene expression changes, and protein differences, present an impenetrably complex set of findings. Network approaches can potentially help integrate and reconcile (...) these findings, as well as provide new insights into the molecular architecture of neuropsychiatric diseases. Network approaches to neuropsychiatric disease are still in their infancy, and we discuss what might be done to improve their prospects. (shrink)

Theory of networks serves as a mathematical foundation for the construction and modeling of chemical structures and complicated networks. In particular, chemical networking theory has a wide range of utilizations in the study of chemical structures, where examination and manipulation of chemical structural information are made feasible by utilizing the numerical graph invariants. A network invariant or a topological index is a numerical measure of a chemical compound which is capable to describe the chemical structural properties such as (...) melting point, freezing point, density, pressure, tension, and temperature of chemical compounds. Wiener initiated the first distance-based TI which is considered to be the most important TI to preserve the chemical and physical properties of chemical structures. Later on, degree-based TI was introduced to find the π -electron energy of molecules. Recently, connection number-based TIs are studied which are more efficient than degree and distance-based TIs. In this paper, we compute the connection number-based TIs of the structure of crystal cubic carbons which are one of the most significant and interesting composites in modern resources of science due to the involvement of carbon atoms. (shrink)

As a result of the time‐ and context‐dependency of gene expression, gene regulatory and signaling pathways undergo dynamic changes during development. Creating a model of the dynamics of molecular interaction networks offers enormous potential for understanding how a genome orchestrates the developmental processes of an organism. The dynamic nature of pathway topology calls for new modeling strategies that can capture transient molecular links at the runtime. The aim of this paper is to present a brief and informative, (...) but not all‐inclusive, viewpoint on the computational aspects of modeling and simulation of a non‐static molecular network. BioEssays 26:68–72, 2004. © 2003 Wiley Periodicals, Inc. (shrink)

This paper investigated the part played by collaborative practices in chaneling the work of prominent biochemists into the development of molecular biology. The RNA collaborative network that emerged in the 1960s in France encompassed a continuum of activities that linked laboratories to policy-making centers. New institutional frameworks such as the DGRST committees were instrumental in establishing new patterns of funding, and in offering arenas for multidisciplinary debates and boundary assessment. It should be stressed however, that although this collaborative network (...) was based on centralized initiatives aimed at developing molecular biology as a new biological specialty, it operated above all as a nexus of practices. The main argument of this paper is that the central allocation of funds and resources, exemplified by the DGRST operation, actually enhanced the creation of a self-conscious community of biochemists turned molecular biologists by virtue of an increased circulation of tools, skills, and results that took place within the RNA network and a few analogous systems of exchange.Having hands on “things” viewed as identical for all practical purposes was a potent factor in changing the experimental systems and their meanings. Limited but shared means of doing helped to reduce uncertainties, change representations, and turn contingent decisions into meaningful choices. The collaborative enterprises then resulted in personal contacts and the transfer of skills and materials, which gradually incorporated the biochemical tools into systems producing facts relevant to molecular biology as defined by its early practitioners. In that sense, networking was a regulatory process that stabilized new research objects and acculturated French biochemists.The mere existence of such a collaborative network also changed the scale of the disciplining process. Collaborations may have been started for contingent motives, but multiple exchanges resulted in the emergence of a new collective, and amplified small displacements. Collaborations, however, worked both ways, and the RNA network may be viewed as an efficient “trading-post.” An unexpected outcome of the development of a conversion zone is the fact that, by the late 1960s, the former biochemists dominated the “new” world of molecular biology — both in terms of research habits, since interests in structural studies dominated the field, and in terms of institutional initiatives such as the creation of laboratories and institutes for molecular biology.As an example of the cognitive displacements achieved by the network, I have focused here on the stabilization of “messenger RNA” as a new biological entity. This process illustrates the role of “boundary objects” and other mediating innovations in the development of disciplinary structures. Students of science trained in the symbolic interactionism tradition have proposed that “boundary objects” enhance the multiple interactions between heterogeneous social worlds: they are robust enough to enhance unity, but plastic enough to be manipulated in different social and cultural contexts.81 Within the emerging network, messenger RNA was a weakly structured “genetic information carrier” in common use, but it could, at the same time, be a strongly structured “macromolecular structure” adapted to practical and local uses. Consequently, messenger RNA favored the association of groups of heterogeneous scientists with backgrounds and interests in medical biochemistry, genetics, physical chemistry, organic chemistry, and so forth. This contrast between general and local uses was also instrumental in integrating the manipulation of things and the negotiation of aims. In contrast to transfer RNAs, which in the French context remained objects for chemical (and mainly structural) studies, messenger RNA became a key component of the new culture of “genetic information”. Messenger RNA was a loose theoretical entity described as a “genetic information carrier” in the policy-making documents, while operational but tacit and more conflicting definitions prevailed at the bench. In other words, messenger RNA was not only a classical “boundary object” but also a “flag object,” which tightened the collaborative network by mediating between the DGRST offices and the laboratories. (shrink)

There is growing interest in the evolutionary dynamics of molecular genetic pathways and networks, and the extent to which the molecular evolution of a gene depends on its position within a pathway or network, as well as over‐all network topology. Investigations on the relationships between network organization, topological architecture and evolutionary dynamics provide intriguing hints as to how networks evolve. Recent studies also suggest that genetic pathway and network structures may influence the action of evolutionary forces, (...) and may play a role in maintaining phenotypic robustness in organisms. BioEssays 26:479–484, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The Neo‐Darwinian concept of natural selection is plausible when one assumes a straightforward causation of phenotype by genotype. However, such simple 1:1 mapping must now give place to the modern concepts of gene regulatory networks and gene expression noise. Both can, in the absence of genetic mutations, jointly generate a diversity of inheritable randomly occupied phenotypic states that could also serve as a substrate for natural selection. This form of epigenetic dynamics challenges Neo‐Darwinism. It needs to incorporate the non‐linear, (...) stochastic dynamics of gene networks. A first step is to consider the mathematical correspondence between gene regulatory networks and Waddington's metaphoric ‘epigenetic landscape’, which actually represents the quasi‐potential function of global network dynamics. It explains the coexistence of multiple stable phenotypes within one genotype. The landscape's topography with its attractors is shaped by evolution through mutational re‐wiring of regulatory interactions – offering a link between genetic mutation and sudden, broad evolutionary changes. (shrink)

The first part of this paper has shown that the development of regulatory genetics and the lactose operon model stemmed from laboratory cultures rooted in local traditions. A "physiological" culture may be recognized in the Pasteurian context. The institutional continuity provided the basis for a tenuous link between Pasteur, Lwoff, and Monod. My claim is that the "national" value of regulatory and physiological genetics is an artifact produced in the course of the legitimization process accompanying the institutionalisation of the discipline. (...) In the 1960s, the lactose operon model was turned into a "flag-object," a symbol of the new culture. The work done by the Pasteurian group became therefore the most important, if not the only, exemplar of molecular biology in France.The second part o f the paper described the origins of general patterns that dominated the building of molecular biology in France. The study of the relationships between molecular biologists and biochemists or immunologists revealed the existence of alternatives to the development of operon research, or to the convergence with molecular biology. Both examples uncover specific paths leading to achievements that might be viewed as international trends: the expansion of RNA and translation studies, and the development of cellular immunology. They illustrate two possible patterns of linking local settings and disciplinary traditions: an oligopolistic situation where a few groups or one institution dominate an entire field, and the emergence of "collective" trends through collaboration networks or schools. (shrink)

Biologists employ a suggestive metaphor to describe the complexities of molecular interactions within cells and embryos: cytological components are said to be part of “ecosystems” that integrate them in a complex network of relations with many other entities. The aim of this essay is to scrutinize the molecular ecosystem, a metaphor that, despite its longstanding history, has seldom be articulated in detail. I begin by analyzing some relevant analogies between the cellular environment and the biosphere. Next, I discuss (...) the applicability of the molecular ecosystem concept in actual scientific practice. (shrink)

The practice and development of modern medicine requires large amounts of data, particularly in the domain of cancer. The future of personalized medicine lies neither with “genomic medicine” nor with “precision medicine”, but with “data medicine”. The establishment of this DM has required far-reaching changes, to establish four essential elements connecting patients and doctors: biobanks, databases, bioinformatic platforms and genomic platforms. The “transformation” of scientific research areas, such as genetics, bioinformatics and biostatistics, into clinical specialties has generated a new vision (...) of care. Molecular tumor boards are one response to these changes and are now providing better access to next-generation sequencing and new cancer treatments to patients with inoperable or metastatic cancers, and those for whom the usual treatment has failed. However, MTB face a crucial ethical challenge: maintaining and improving the trust of patients, clinicians, researchers and industry in academic medical centers supported by private or public funding rather than providing genetic data directly to private companies. We believe that, in this era of DM, appropriate modern digital communication networks will be required to maintain this trust and to improve the organization and effectiveness of the system. There is, therefore, a need to reconsider the form and content of informed consent documents at all academic medical centers and to introduce dynamic and electronic informed consent. (shrink)

Since the publication of Nikolas Rose’s ‘The Politics of Life Itself’ there has been vivid discussion about how biopolitical governance has changed over the last decades. This article uses what Rose terms ‘molecular politics’, a new socio-technical grip on the human body, as a contrasting background to ask anew his question ‘What, then, of biopolitics today?’ – albeit focusing not on advances in genetics, microbiology, and pharmaceutics, as he does, but on the rapid proliferation of wearables and other sensor-software (...) gadgets. In both cases, new technologies providing information about the individual body are the common ground for governance and optimization, yet for the latter, the target is habits of moving, eating and drinking, sleeping, working and relaxing. The resulting profound differences are carved out along four lines: ‘somatic identities’ and a modified understanding of the body; the role of ‘expert knowledge’ compared to that of networks of peers and self-experimentation; the ‘types of intervention’ by which new technologies become effective in our everyday life; and the ‘post-discipline character’ of molecular biopolitics. It is argued that, taken together, these differences indicate a remarkable shift which could be termed aretaic: its focus is not ‘life itself’ but ‘life as it is lived’, and its modality are new everyday socio-technical entanglements and their more-than-human rationalities of governance. (shrink)

We apply molecular code theory to a rule-based model of the human inner kinetochore and study how complex formation in general can give rise to molecular codes. We analyze 105 reaction networks generated from the rule-based inner kinetochore model in two variants: with and without dissociation of complexes. Interestingly, we found codes only when some but not all complexes are allowed to dissociate. We show that this is due to the fact that in the kinetochore model proteins (...) can only bind at kinetochores by attaching to already attached proteins and cannot form complexes in free solution. Using a generalized linear mixed model we study which centromere protein can take which role in a molecular code . By this, associations between CENPs and code roles are found. We observed that CenpA is a major risk factor while CenpQ is a major protection factor . Finally we show, using an abstract model of copolymer formation, that molecular codes can also be realized solely by the formation of stable complexes, which do not dissociate. For example, with particular dimers as context a molecular code mapping from two different monomers to two particular trimers can be realized just by non-selective complex formation. We conclude that the formation of protein complexes can be utilized by the cell to implement molecular codes. Living cells thus facilitate a subsystem allowing for an enormous flexibility in the realization of mappings, which can be used for specific regulatory processes, e.g. via the context of a mapping. (shrink)

Significant progress in the molecular investigation of endogenous bioelectric signals during pattern formation in growing tissues has been enabled by recently developed techniques. Ion flows and voltage gradients produced by ion channels and pumps are key regulators of cell proliferation, migration, and differentiation. Now, instructive roles for bioelectrical gradients in embryogenesis, regeneration, and neoplasm are being revealed through the use of fluorescent voltage reporters and functional experiments using well‐characterized channel mutants. Transmembrane voltage gradients (Vmem) determine anatomical polarity and function (...) as master regulators during appendage regeneration and embryonic left‐right patterning. A state‐of‐the‐art recent study reveals that they can also serve as prepatterns for gene expression domains during craniofacial patterning. Continued development of novel tools and better ways to think about physical controls of cell‐cell interactions will lead to mastery of the morphogenetic information stored in physiological networks. This will enable fundamental advances in basic understanding of growth and form, as well as transformative biomedical applications in regenerative medicine. (shrink)

The practice and development of modern medicine requires large amounts of data, particularly in the domain of cancer. The future of personalized medicine lies neither with “genomic medicine” nor with “precision medicine”, but with “data medicine”. The establishment of this DM has required far-reaching changes, to establish four essential elements connecting patients and doctors: biobanks, databases, bioinformatic platforms and genomic platforms. The “transformation” of scientific research areas, such as genetics, bioinformatics and biostatistics, into clinical specialties has generated a new vision (...) of care. Molecular tumor boards are one response to these changes and are now providing better access to next-generation sequencing and new cancer treatments to patients with inoperable or metastatic cancers, and those for whom the usual treatment has failed. However, MTB face a crucial ethical challenge: maintaining and improving the trust of patients, clinicians, researchers and industry in academic medical centers supported by private or public funding rather than providing genetic data directly to private companies. We believe that, in this era of DM, appropriate modern digital communication networks will be required to maintain this trust and to improve the organization and effectiveness of the system. There is, therefore, a need to reconsider the form and content of informed consent documents at all academic medical centers and to introduce dynamic and electronic informed consent. (shrink)

Molecular imprints of organisms serving as both the agents and the products of the underlying sign activities are quantum mechanical in their origins. In particular, molecules in any reaction networks constituting a biological organism are semiotic or context-dependent in the sense that their activities reside within the proper coordination of the entire networks. The origin of life could have been related to a specific aspect of molecular semiotics, especially in the transition from molecules as the physical (...) symbols of material units to molecules as the semiotic signs having the capacity of pointing to something else other than the molecules themselves. Quantum mechanical underpinning of the molecular imprints leading to the emergence of life is in the appraisal of the material capacities of both coherent assimilation and decoherent dissociation already latent in the imprints. One empirical evidence suggesting the likelihood of both coherent assimilation and decoherent dissociation in prebiotic settings could have been found in synthetic chemical reactions running in hydrothermal circulation of seawater through hot vents in the Haedean ocean on the primitive Earth. (shrink)

Mechanical stimulation has a critical role in the development and maintenance of the skeleton. This function requires the perception of extracellular stimuli as well as their conversion into intracellular biochemical responses. This process is called mechanotransduction and is mediated by a plethora of molecular events that regulate bone metabolism. Indeed, mechanoreceptors, such as integrins, G protein‐coupled receptors, receptor protein tyrosine kinases, and stretch‐activated Ca2+ channels, together with their downstream effectors coordinate the transmission of load‐induced signals to the nucleus and (...) the expression of bone‐related genes. During the past decade, scientists have gained increasing insight into the molecular networks implicated in bone mechanotransduction. In the present paper, we consider the major signaling cascades and transcription factors that control bone and cartilage mechanobiology and discuss the influence of the mechanical microenvironment on the determination of skeletal morphology. (shrink)

Mechanistic models in molecular systems biology are generally mathematical models of the action of networks of biochemical reactions, involving metabolism, signal transduction, and/or gene expression. They can be either simulated numerically or analyzed analytically. Systems biology integrates quantitative molecular data acquisition with mathematical models to design new experiments, discriminate between alternative mechanisms and explain the molecular basis of cellular properties. At the heart of this approach are mechanistic models of molecular networks. We focus on (...) the articulation and development of mechanistic models, identifying five constraints which guide the articulation of models in molecular systems biology. These constraints are not independent of one another, with the result that modeling becomes an iterative process. We illustrate the use of these constraints in the modeling of the mechanism for bistability in the lac operon. (shrink)

An astonishingly diverse biomolecular circuitry orchestrates the functioning machinery underlying every living cell. These biomolecules and their circuits have been engineered not only for various industrial applications but also to perform other atypical functions that they were not evolved for—including computation. Various kinds of computational challenges, such as solving NP‐complete problems with many variables, logical computation, neural network operations, and cryptography, have all been attempted through this unconventional computing paradigm. In this review, we highlight key experiments across three different ‘‘eras’’ (...) of molecular computation, beginning with molecular solutions, transitioning to logic circuits and ultimately, more complex molecular networks. We also discuss a variety of applications of molecular computation, from solving NP‐hard problems to self‐assembled nanostructures for delivering molecules, and provide a glimpse into the exciting potential that molecular computing holds for the future. Also see the video abstract here: https://youtu.be/9Mw0K0vCSQw. (shrink)

Systems biology provides alternatives to the strategies to developing mechanistic explanations traditionally pursued in cell and molecular biology and much discussed in accounts of mechanistic explanation. Rather than starting by identifying a mechanism for a given phenomenon and decomposing it, systems biologists often start by developing cell-wide networks of detected connections between proteins or genes and construe clusters of highly interactive components as potential mechanisms. Using inference strategies such as ‘guilt-by-association’, researchers advance hypotheses about functions performed of these (...) mechanisms. I examine several examples of research on budding yeast, first on what are taken to be enduring networks and subsequently on networks that change as cells perform different activities or respond to different external conditions. (shrink)

Together with microtubules and actin microfilaments, ∼11 nm wide intermediate filaments (IFs) constitute the integrated, dynamic filament network present in the cytoplasm of metazoan cells. This network is critically involved in division, motility and other cellular processes. While the structures of microtubules and microfilaments are known in atomic detail, IF architecture is presently much less understood. The elementary ‘building block’ of IFs is a highly elongated, rod‐like dimer based on an α‐helical coiled‐coil structure. Assembly of cytoplasmic IF proteins, such as (...) vimentin, begins with a lateral association of dimers into tetramers and gradually into the so‐called unit‐length filaments (ULFs). Subsequently ULFs start to anneal longitudinally, ultimately yielding mature IFs after a compaction step. For nuclear lamins, however, assembly starts with a head‐to‐tail association of dimers. Recently, X‐ray crystallographic data were obtained for several fragments of the vimentin dimer. Based on the dimer structure, molecular models of the tetramer and the entire filament are now a possibility. BioEssays 25:243–251, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Reproduction and immunity are energy intensive, intimately linked processes in most organisms. In women, pregnancy is associated with widespread immunological adaptations that alter immunity to many diseases, whereas, immune dysfunction has emerged as a major cause for infertility in both men and women. Deciphering the molecular bases of this dynamic association is inherently challenging in mammals. This relationship has been traditionally studied in fast‐living, invertebrate species, often in the context of resource allocation between life history traits. More recently, these (...) studies have advanced our understanding of the mechanistic underpinnings of the immunity‐fertility dialogue. Here, we review the molecular connections between reproduction and immunity from the perspective of human pregnancy to mechanistic discoveries in laboratory organisms. We focus particularly on recent invertebrate studies identifying conserved signaling pathways and transcription factors that regulate resource allocation and shape the balance between reproductive status and immune health. (shrink)

Molecular codes can be considered a special type of mapping among molecular species in biochemical systems. The formalization of molecular codes allows to identify these in network models of real world systems. Analyzing algorithmically identified codes leads to the observation that codes does not necessarily stand alone, but that we can identify certain relations among codes. In this paper I will define two types of relations that can occur among codes, code linkage and code nesting, and will (...) discuss implications of this finding. (shrink)

Arguably, no psychological variable has received more attention from behavioral geneticists than what has been called “general cognitive ability” (as well as “general intelligence” or “g”), and for good reason. GCA has a rich correlational network, implying that it may play an important role in multiple domains of functioning. GCA is highly correlated with various indicators of educational attainment, yet its predictive utility is not limited to academic achievement. It is also correlated with work performance, navigating the complexities of everyday (...) life, the absence of various social pathologies (such as criminal convictions), and even health and mortality. Although the causal basis for these associations is not always known, it is nonetheless the case that research on GCA has the potential to provide insights into the origins of a wide range of important social outcomes. In this essay, our discussion of why GCA is considered a fundamentally important dimension of behavior on which humans differ is followed by a look at behavioral genetics research on CGA. We summarize behavioral genetics research that has sought to identify and quantify the total contributions of genetic and environmental factors to individual differences in GCA as well as molecular genetic research that has sought to identify genetic variants that underlie inherited effects. (shrink)

Over the last two decades, network-focused approaches have become highly popular in diverse fields of biology, including neuroscience, ecology, molecular biology and genetics. While the network approach continues to grow very rapidly, some of its conceptual and methodological aspects still require a programmatic foundation. This challenge particularly concerns the question of whether a generalized account of explanatory, organisational and descriptive levels of networks can be applied universally across biological sciences. Consequently, the central focus of this theme issue will (...) be on the definition, motivation and application of key concepts in biological network science, such as levels, hierarchies, and explanatory directionality. A unification will be achieved by formulating norms for delimiting the distinctively network-topological class of explanations that connect general as well as very specific biological research questions. The impact of this theme issue is broad and encompassing, as it is highly interdisciplinary and opens a uniquely normative perspective on the foundational aspects of network-based explanations and modelling. This theme issue is intended to become a landmark publication for practical research as well as funding policy decisions, by unifying network approaches in biological sciences in terms of fundamental concepts and informing the public understanding of the network science. (shrink)

In mammalian cells, a complex network of signaling pathways tightly regulates a variety of cellular processes, such as proliferation and differentiation. New insights from one of the most‐important signaling cascades involved in oncogenesis, the Ras–Raf–MAPK pathway, suggest that the subcellular localisation and assembly of signaling modules of this pathway is crucial to control the biological response. This commonly requires membrane targeting events that are mediated by adaptor/scaffold proteins. Of particular interest is the translocation and complex formation of GTPase‐activating proteins (GAPs), (...) such as p120GAP, at the plasma membrane to inactivate Ras. Recent studies indicate that one member of the annexin family, annexin A6 acts as a targeting protein for p120GAP. This review discusses how annexin A6 modulates the involvement of negative regulators of the Ras–Raf–MAPK pathway contributing to Ras inactivation. BioEssays 28: 1211–1220, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

Recent studies have revealed an astonishing diversity of sex chromosomes in many vertebrate lineages, prompting questions about the mechanisms of sex chromosome turnover. While there is considerable population genetic theory about the evolutionary forces promoting sex chromosome replacement, this theory has not yet been integrated with our understanding of the molecular and developmental genetics of sex determination. Here, we review recent data to examine four questions about how the structure of gene networks influences the evolution of sex determination. (...) We argue that patterns of epistasis, arising from the structure of genetic networks, may play an important role in regulating the rates and patterns of sex chromosome replacement. (shrink)

Biochemical networks are often called upon to illustrate emergent properties of living systems. In this contribution, I question such emergentist claims by means of theoretical work on genetic regulatory models and random Boolean networks. If the existence of a critical connectivity Kc of such networks has often been coined “emergent” or “irreducible”, I propose on the contrary that the existence of a critical connectivity Kc is indeed mathematically explainable in network theory. This conclusion also applies to many (...) other types of formal networks and weakens the emergentist claim attached to bio-molecular networks, and by extension to living systems. (shrink)

Scientific anomalies are observations and facts that contradict current scientific theories and they are instrumental in scientific theory change. Philosophers of science have approached scientific theory change from different perspectives as Darden (Theory change in science: Strategies from Mendelian genetics, 1991) observes: Lakatos (In: Lakatos, Musgrave (eds) Criticism and the growth of knowledge, 1970) approaches it as a progressive “research programmes” consisting of incremental improvements (“monster barring” in Lakatos, Proofs and refutations: The logic of mathematical discovery, 1976), Kuhn (The structure (...) of scientific revolutions, 1996) observes that changes in “paradigms” are instigated by a crisis from some anomaly, and Hanson (In: Feigl, Maxwell (eds) Current issues in the philosophy of science, 1961) proposes that discovery does not begin with hypothesis but with some “problematic phenomena requiring explanation”. Even though anomalies are important in all of these approaches to scientific theory change, there have been only few investigations into the specific role anomalies play in scientific theory change. Furthermore, much of these approaches focus on the theories themselves and not on how the scientists and their experiments bring about scientific change (Gooding, Experiment and the making of meaning: Human agency in scientific observation and experiment, 1990). To address these issues, this paper approaches scientific anomaly resolution from a meaning construction point of view. Conceptual integration theory (Fauconnier and Turner, Cogn Sci 22:133–187, 1996; The way we think: Conceptual blending and mind’s hidden complexities, 2002) from cognitive linguistics describes how one constructs meaning from various stimuli, such as text and diagrams, through conceptual integration or blending. The conceptual integration networks that describe the conceptual integration process characterize cognition that occurs unconsciously during meaning construction. These same networks are used to describe some of the cognition while resolving an anomaly in molecular genetics called RNA interference (RNAi) in a case study. The RNAi case study is a cognitive-historical reconstruction (Nersessian, In: Giere (ed) Cognitive models of science, 1992) that reconstructs how the RNAi anomaly was resolved. This reconstruction traces four relevant molecular genetics publications in describing the cognition necessary in accounting for how RNAi was resolved through strategies (Darden 1991), abductive reasoning (Peirce, In: Hartshorne, Weiss (eds) Collected papers, 1958), and experimental reasoning (Gooding 1990). The results of the case study show that experiments play a crucial role in formulating an explanation of the RNAi anomaly and the integration networks describe the experiments’ role. Furthermore, these results suggest that RNAi anomaly resolution is embodied. It is embodied in a sense that cognition described in the cognitive-historical reconstruction is experientially based. (shrink)

How is a disease contracted, and how does it progress through the body? Answers to these questions are fundamental to understanding both basic biology and medicine. Advances in the biomedical sciences continue to provide more tools to address these fundamental questions and to uncover questions that have not been thought of before. Despite these major advances, we are still facing conceptual and technical challenges when learning about the etiology of disease, especially for genetic diseases. In this review, we illustrate this (...) point by discussing the causal links between molecular mechanisms and systems-level phenotypes in molecular diseases. We begin with an examination of sickle cell anemia, and how mechanisms of the disease have been comprehended over the last century. While sickle cell anemia involves a mutation in a single protein in a single cell type, other diseases involve mutations in networks with many protein interactions and in diverse cell types. We introduce the challenges that result from these differences and illustrate the current obstacles by discussing the RASopathies, a recently discovered class of developmental syndromes that result from mutations in signaling networks. Methods to study mutant genotypes that lead to mutant phenotypes are discussed, particularly the use of model organisms and mutant proteins to study protein interactions that may be important for development of disease. These studies will point toward the future of diagnosing and treating genetic disease. (shrink)

Background The emergence of molecular HIV surveillance (MHS) and cluster detection and response (CDR) programs as key features of the United States (US) HIV strategy since 2018 has caused major controversies. HIV surveillance programs that re-use individuals’ routinely collected clinical HIV data do not require consent on the basis that the public benefit of these programs outweighs individuals’ rights to opt out. However, criticisms of MHS/CDR have questioned whether expanded uses of HIV genetic sequence data for prevention reach beyond (...) traditional public health ethics frameworks. This study aimed to explore views on consent within MHS/CDR among critical stakeholders.Methods In 2021 we interviewed 26 US HIV stakeholders who identified as being critical or concerned about the rollout of MHS/CDR. Stakeholders included participants belonging to networks of people living with HIV, other advocates, academics, and public health professionals. This analysis focused on identifying the range of positions among critical and concerned stakeholders on consent affordances, opt-outs, how to best inform people living with HIV about how data about them are used in public health programs, and related ethical issues.Results Participants were broadly supportive of introducing some forms of consent into MHS/CDR. However, they differed on the specifics of implementing consent. While some participants did not support introducing consent affordances, all supported the idea that people living with HIV should be informed about how HIV surveillance and prevention is conducted and how individuals’ data are used.Conclusions MHS/CDR has caused sustained controversy. Among critical stakeholders, consent is generally desirable but contested, although the right for people living with HIV to be informed was centrally supported. In an era of big data-driven public health interventions and routine uses of HIV genetic sequence data in surveillance and prevention, CDC and other agencies should revisit public health ethics frameworks and consider the possibility of consent processes. (shrink)

The lymphatic vasculature comprises an intricate network of vessels critical for fluid homeostasis, immune surveillance and fat absorption. Recent studies have provided insights into the developmental processes and molecular mechanisms controlling the formation and remodelling of the lymphatic vessels. These studies have further demonstrated the essential and active role of the lymphatic vessels in various pathological conditions and advanced our understanding of the progression of human diseases, such as inflammation and tumorigenesis. In the context of the latest exciting findings, (...) we review here the current understanding of the mechanisms of lymphatic development and contribution of lymphatic vessels to pathological conditions. BioEssays 29:1192–1202, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

The establishment of a functional vascular system requires multiple complex steps throughout embryogenesis, from endothelial cell (EC) specification to vascular patterning into venous and arterial hierarchies. Following the initial assembly of ECs into a network of cord‐like structures, vascular expansion and remodeling occur rapidly through morphogenetic events including vessel sprouting, fusion, and pruning. In addition, vascular morphogenesis encompasses the process of lumen formation, critical for the transformation of cords into perfusable vascular tubes. Studies in mouse, zebrafish, frog, and human endothelial (...) cells have begun to outline the cellular and molecular requirements underlying lumen formation. Although the lumen can be generated through diverse mechanisms, the coordinated participation of multiple conserved molecules including transcription factors, small GTPases, and adhesion and polarity proteins remains a fundamental principle, leading us closer to a more thorough understanding of this complex event. (shrink)

A comparison of six alternative definitions of the term 'cellular pathway' against the background of ontological realism.

BackgroundHIV molecular epidemiology is increasingly recognized as a vital source of information for understanding HIV transmission dynamics. Despite extensive use of these data-intensive techniques in both research and public health settings, the ethical issues associated with this science have received minimal attention. As the discipline evolves, there is reasonable concern that existing ethical and legal frameworks and standards might lag behind the rapid methodological developments in this field. This is a follow-up on our earlier work that applied a predetermined (...) analytical framework to examine the perspectives of a sample of scientists from the fields of epidemiology, public health, virology and bioethics on key ethical issues associated with HIV molecular epidemiology in HIV network research.MethodsFourteen in-depth interviews were conducted with scientists from the fields of molecular epidemiology, public health, virology and bioethics. Inductive analytical approaches were applied to identify key themes that emerged from the data.ResultsOur interviewees acknowledged the potential positive impact of molecular epidemiology in the fight against HIV. However, they were concerned that HIV phylogenetics research messages may be incorrectly interpreted if not presented at the appropriate level. There was consensus that HIV phylogenetics research presents a potential risk to privacy, but the probability and magnitude of this risk was less obvious. Although participants acknowledged the social value that could be realized from the analysis of HIV genetic sequences, there was a perceived fear that the boundaries for use of HIV sequence data were not clearly defined.ConclusionsOur findings highlight distinct ethical issues arising from HIV molecular epidemiology. As the discipline evolves and HIV sequence data become increasingly available, it is critical to ensure that ethical standards keep pace with biomedical advancements. We argue that the ethical issues raised in this study, whether real or perceived, require further conceptual and empirical examination. (shrink)

This paper is devoted to an examination of the discovery, characterization, and analysis of the functions of microRNAs, which also serves as a vehicle for demonstrating the importance of exploratory experimentation in current (post-genomic) molecular biology. The material on microRNAs is important in its own right: it provides important insight into the extreme complexity of regulatory networks involving components made of DNA, RNA, and protein. These networks play a central role in regulating development of multicellular organisms and (...) illustrate the importance of epigenetic as well as genetic systems in evolution and development. The examination of these matters yields principled arguments for the historicity of the functions of key biological molecules and for the indispensability of exploratory experimentation in contemporary molecular biology as well as some insight into the complex interplay between exploratory experimentation and hypothesis-driven science. This latter result is not only important for philosophy of science, but also of practical importance for the evaluation of grant proposals, although the elaboration of this latter claim must be left for another occasion. (shrink)

Over the last decades, network-based approaches have become highly popular in diverse fields of biology, including neuroscience, ecology, molecular biology and genetics. While these approaches continue to grow very rapidly, some of their conceptual and methodological aspects still require a programmatic foundation. This challenge particularly concerns the question of whether a generalized account of explanatory, organisational and descriptive levels of networks can be applied universally across biological sciences. To this end, this highly interdisciplinary theme issue focuses on the (...) definition, motivation and application of key concepts in biological network science, such as explanatory power of distinctively network explanations, network levels, and network hierarchies. (shrink)

Biology arises from the crowded molecular environment of the cell, rendering it a challenge to understand biological pathways based on the reductionist, low‐concentration in vitro conditions generally employed for mechanistic studies. Recent evidence suggests that low‐affinity interactions between cellular biopolymers abound, with still poorly defined effects on the complex interaction networks that lead to the emergent properties and plasticity of life. Mass‐action considerations are used here to underscore that the sheer number of weak interactions expected from the complex (...) mixture of cellular components significantly shapes biological pathway specificity. In particular, on‐pathway—i.e., “functional”—become those interactions thermodynamically and kinetically stable enough to survive the incessant onslaught of the many off‐pathway (“nonfunctional”) interactions. Consequently, to better understand the molecular biology of the cell a further paradigm shift is needed toward mechanistic experimental and computational approaches that probe intracellular diversity and complexity more directly. Also see the video abstract here https://youtu.be/T19X_zYaBzg. (shrink)

DNA–protein interactions are fundamental to many biological processes, including the regulation of gene expression. Determining the binding affinities of transcription factors (TFs) to different DNA sequences allows the quantitative modeling of transcriptional regulatory networks and has been a significant technical challenge in molecular biology for many years. A recent paper by Maerkl and Quake1 demonstrated the use of microfluidic technology for the analysis of DNA–protein interactions. An array of short DNA sequences was spotted onto a glass slide, which (...) was then covered with a microfluidic device allowing each spot to be within a chamber into which the flow of materials was controlled by valves. By trapping the DNA–protein complexes on the surface and measuring their concentrations microscopically, they could determine the binding affinity to a large number of DNA sequences that were varied systematically. They studied four TFs from the basic helix–loop–helix family of proteins, all of which bind to E‐box sites with the consensus CAnnTG (where “n” can be any base), and showed that variations in affinity for different sites allows each TF to regulate different genes. BioEssays 29:717–721, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

A highly useful resource for professionals and students alike, this cutting-edge, first-of-its-kind book provides a thorough introduction to nanoscale communication networks. Written in a clear tutorial style, this volume covers a wide range of the most important topics in the area, from molecular communication and carbon nanotube nano-networks, to nanoscale quantum networking and the future direction of nano networks. Moreover, the book features numerous exercise problems at the end of each chapter to ensure a solid understanding (...) of the material. (shrink)

The paper focuses on knowledge generation, a topic frequently overlooked in the traditional debates in epistemology and philosophy of science. We focus on investigation as the primary process generating knowledge and its products. Investigation is taken as a generalization of the research process that includes similar knowledge-generating practices in aboriginal communities. To characterize the complexity of investigation processes and their products we go beyond traditional epistemological characterization of knowledge in terms of mental states and turn to the concept of routine. (...) Investigation processes share a common symbolic representation form which we call here a knowledge thread. The dynamics of the knowledge thread may be characterized by two intertwined tiers: cognitive and institutional. Using examples from our previous studies, especially on the recent discovery of microRNAs in molecular biology, we illustrate the dynamics of threads and claim that it is susceptible to the social network analysis which, however, requires insightful applications and sound interpretation of the results. Such an interpretation, as we suggest, may further be elaborated on the grounds of anthropological theories of distributed agency and distributed cognition. (shrink)

Despite the recent progress in the description of the molecular mechanisms of proliferation and differentiation controls in vitro, the regulation of the homeostasis of normal stratified epithelia remains unclear in vivo. Computer simulation represents a powerful tool to investigate the complex field of cell proliferation regulation networks. It provides huge computation capabilities to test, in a dynamic in silico context, hypotheses about the many pathways and feedback loops involved in cell growth and proliferation controls.Our approach combines a model (...) of cell proliferation and a spatial representation of cells in 2D using the Voronoi graph. The cell proliferation model includes intracellular (cyclins, Cyclin Dependent Kinases - CDKs, Retinoblastoma protein - Rb, CDK inhibitors) and extracellular controls (growth and differentiation factors, integrins). The Voronoi graph associates a polygon with every cell and the set of these polygons defines the tissue architecture. Thus, the model provides a quantitative model of extracellular signals and cell motility as a function of the neighborhood during time dependent simulations. (shrink)

Advances in molecular technologies have the potential to help remedy health inequities through earlier detection and prevention; if, however, their delivery and uptake are not more carefully considered, there is a very real risk that existing inequities in access and use will be further exacerbated. We argue this risk relates to the way that information and knowledge about the technology is both acquired and shared, or not, between health practitioners and their patients.A healthcare system can be viewed as a (...) complex social network comprising individuals with different worldviews, hierarchies, professional cultures and subcultures and personal beliefs, both for those giving and receiving care. When healthcare practitioners are not perceived as knowledge equals, they would experience informational prejudices, and the result is that knowledge dissemination across and between them would be impeded. The uptake and delivery of a new technology may be inequitable as a result. Patients would also experience informational prejudice when they are viewed as not being able to understand the information that is presented to them, and information may be withheld.Informational prejudices driven by social relations and structures have thus far been underexplored in considering equitable implementation and uptake of new molecular technologies. Every healthcare interaction represents an opportunity for experiencing informational prejudice, and with it the risk of being inappropriately informed for undertaking such screening or testing. Making knowledge acquisition and information dissemination, and experiences of informational prejudice, explicit through sociologically framed investigations would extend our understandings of equity, and offer ways to affect network relationships and structures that support equity in delivery and uptake. (shrink)

This paper examines processes of translation through which molecular genetic technologies and practices are incorporated into environmental health research and regulation. Specifically, it considers how scientists, risk assessors, and regulators have used genetically modified mouse models to translate across scientific disciplines, articulate emergent molecular forms, standards, and practices with the extant? gold standard,? and establish roles for molecular knowledge in risk assessment and regulation. Noting variation both within and between regulatory agencies in responses to data from these (...) models, the article describes also the role of public-private networks and their effects on professional and institutional imperatives which shape regulators? responses to the potential applications of these models. The conclusions address the importance of translation for understanding the wider implications of the molecularization of environmental health science. (shrink)