Understanding aging and how it affects an organism's lifespan is a fundamental problem in biology. A hallmark of aging is stem cell senescence, the decline of functionality, and number of somatic stem cells, resulting in an impaired regenerative capacity and reduced tissue function. In addition, aging is characterized by profound remodeling of the immune system and a quantitative decline of adequate immune responses, a phenomenon referred to as immune‐senescence. Yet, what is causing stem cell and immune‐senescence? This review discusses experimental (...) studies of potentially immortal Hydra which have made contributions to answering this question. Hydra transcription factor FoxO has been shown to modulate both stem cell proliferation and innate immunity, lending strong support to a role of FoxO as critical rate‐of‐aging regulator from Hydra to human. Constructing a model of how FoxO responds to diverse environmental factors provides a framework for how stem cell factors might contribute to aging. (shrink)

Cover Photograph: Transgenic Hydra provide insights of general relevance into stem cell biology. The image shows a mass culture of transgenic Hydra expressing EGFP in all of their ectodermal epithelial cells. See article by Thomas C. G. Bosch pp. 478–486.

Cells in the basal metazoan phylum Cnidaria are characterized by remarkable plasticity in their differentiation capacity. The mechanism controlling asymmetric cell divisions is not understood in cnidarians or in any other animal group. PIWI proteins recently have been shown to be involved in maintaining the self‐renewal capacity of stem cells in organisms as diverse as ciliates, flies, worms and mammals. Seipel et al.1 find that, in the cnidarian Podocoryne carnea, the Piwi homolog Cniwi is transcriptionally upregulated when the polyp generates (...) buds, which will develop into medusae. Since transdifferentiation of striated muscle cells to smooth muscle cells also activated Cniwi expression, Cniwi appears to play a crucial role in differentiation events. The discovery should facilitate elucidation of the poorly understood factors that control asymmetric cell divisions at the beginning of animal evolution. BioEssays 26:929–931, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Hydra are remarkable because they are immortal. Much of immortality can be ascribed to the asexual mode of reproduction by budding, which requires a tissue consisting of stem cells with continuous self‐renewal capacity. Emerging novel technologies and the availability of genomic resources enable for the first time to analyse these cells in vivo. Stem cell differentiation in Hydra is governed through the coordinated actions of conserved signaling pathways. Studies of stem cells in Hydra, therefore, promise critical insights of general relevance (...) into stem cell biology including cellular senescence, lineage programming and reprogramming, the role of extrinsic signals in fate determination and tissue homeostasis, and the evolutionary origin of these cells. With these new facts as a backdrop, this review traces the history of studying stem cells in Hydra and offers a view of what the future may hold. (shrink)

Current work in experimental biology revolves around a handful of animal species. Studying only a few organisms limits science to the answers that those organisms can provide. Nature has given us an overwhelming diversity of animals to study, and recent technological advances have greatly accelerated the ability to generate genetic and genomic tools to develop model organisms for research on host–microbe interactions. With the help of such models the authors therefore hope to construct a more complete picture of the mechanisms (...) that underlie crucial interactions in a given metaorganism (entity consisting of a eukaryotic host with all its associated microbial partners). As reviewed here, new knowledge of the diversity of host–microbe interactions found across the animal kingdom will provide new insights into how animals develop, evolve, and succumb to the disease. (shrink)

Peptides serve as important signalling molecules in development and differentiation in the simple metazoan Hydra. A systematic approach (The Hydra Peptide Project) has revealed that Hydra contains several hundreds of peptide signalling molecules, some of which are neuropeptides and others emanate from epithelial cells. These peptides control biological processes as diverse as muscle contraction, neuron differentiation, and the positional value gradient. Signal peptides cause changes in cell behaviour by controlling target genes such as matrix metalloproteases. The abundance of peptides in (...) Hydra raises the question of whether, in early metazoan evolution, cell–cell communication was based mainly on these small molecules rather than on the growth‐factor‐like cytokines that control differentiation and development in higher animals. BioEssays 23:420–427, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Ecological developmental biology (eco‐devo) explores the mechanistic relationships between the processes of individual development and environmental factors. Recent studies imply that some of these relationships have deep evolutionary origins, and may even pre‐date the divergences of the simplest extant animals, including cnidarians and sponges. Development of these early diverging metazoans is often sensitive to environmental factors, and these interactions occur in the context of conserved signaling pathways and mechanisms of tissue homeostasis whose detailed molecular logic remain elusive. Efficient methods for (...) transgenesis in cnidarians together with the ease of experimental manipulation in cnidarians and sponges make them ideal models for understanding causal relationships between environmental factors and developmental mechanisms. Here, we identify major questions at the interface between animal evolution and development and outline a road map for research aimed at identifying the mechanisms that link environmental factors to developmental mechanisms in early diverging metazoans.Also watch the Video Abstract. (shrink)

Graphical AbstractCIFAR's Humans & the Microbiome program is a multidisciplinary group of biological, clinical, and social scientists who explore the links between microbiome biology and sociocultural, historical, evolutionary, and environmental aspects of human existence that may impact the microbiome or be impacted by it. In this focus issue, members of the program focus on topics ranging from decoding the link between nutrition, the microbiome and human developmental, metabolic, and immune health and aging, to understanding past changes in the environment and (...) microbiome. The image depicts a population of bacteria (green) in association with the epithelia tissues (magenta and blue), perhaps the most common type of symbiosis in humans and other animals. Image contribution: Tara Essock-Burns. DOI: 10.1002/bies.201900130. (shrink)

Here we evaluate our current understanding of the function of the nervous system in Hydra, a non‐bilaterian animal which is among the first metazoans that contain neurons. We highlight growing evidence that the nervous system, with its rich repertoire of neuropeptides, is involved in controlling resident beneficial microbes. We also review observations that indicate that microbes affect the animal's behavior by directly interfering with neuronal receptors. These findings provide new insight into the original role of the nervous system, and suggest (...) that it emerged to orchestrate multiple functions including host‐microbiome interactions. The excitement of future research in the Hydra model now relies on uncovering the common rules and principles that govern the interaction between neurons and microbes and the extent to which such laws might apply to other and more complex organisms. (shrink)

While largely studied because of their harmful effects on human health, there is growing appreciation that bacteria are important partners for invertebrates and vertebrates, including man. Epithelia in metazoans do not only select their microbiota; a coevolved consortium of microbes enables both invertebrates and vertebrates to expand the range of diet supply, to shape the complex immune system and to control pathogenic bacteria. Microbes in zebrafish and mice regulate gut epithelial homeostasis. In a squid, microbes control the development of the (...) symbiotic light organ. These discoveries point to a key role for bacteria in any metazoan existence, and imply that beneficial bacteria‐host interactions should be considered an integral part of development and evolution. (shrink)

The conference explored an extraordinary diversity of aging strategies in organisms ranging from short‐lived species to “immortal” animals and plants. Research on the biological processes of aging is at the brink of a revolution with respect to our understanding of its underlying mechanisms as well as our ability to prevent and cure a wide variety of age‐related pathologies.

A reality-design gap in the conceptualization and practice of digital agriculture has been systematically reported in the literature. This condition is favored by the lack of understanding and inclusion of local worldviews around digital technologies. Informed by Amartya Sen’s capabilities approach, this study looks to bring stories of local appropriation to the spotlight. Based on a qualitative approach that included data collected through interviews with 73 households, the authors explored the way in which two selected communities of Colombian coffee growers (...) are engaged in the use of digital technologies in material and symbolic ways. Three emergent themes—a relational way of farming, (dis)connected machines, and nurtured families and communities – articulate multiple interactions between farmers, farms, institutional programs, and technologies, that originate local forms of digitalization (and non-digitalization). This study points out the relevant role of situated ideas of development in positioning technologies in or out of the farm, and broader digitalization agendas in or out of farmers’ life projects. At the same time, it presents a critique of notions of universality that drive unquestioned quests for technification. In contrast, building on a relational perspective, this study calls for embracing a perspective of multiplicity within notions of development and innovation. (shrink)

Humans’ indigenous microbes strongly influence organ functions in an age‐ and diet‐dependent manner, adding an important dimension to aging biology that remains poorly understood. Although age‐related differences in the gut microbiota composition correlate with age‐related loss of organ function and diseases, including inflammation and frailty, variation exists among the elderly, especially centenarians and people living in areas of extreme longevity. Studies using short‐lived as well as nonsenescent model organisms provide surprising functional insights into factors affecting aging and implicate attenuating effects (...) of microbes as well as a crucial role for certain transcription factors like forkhead box O. The unexpected beneficial effects of microbes on aged animals imply an even more complex interplay between the gut microbiome and the host. The microbiome constitutes the major interface between humans and the environment, is influenced by biosocial stressors and behaviors, and mediates effects on health and aging processes, while being moderated by sex and developmental stages. (shrink)

The microbiome of human hair follicles (HFs) has emerged as an important player in different HF and skin pathologies, yet awaits in‐depth exploration. This raises questions regarding the tightly linked interactions between host environment, nutrient dependency of host‐associated microbes, microbial metabolism, microbe‐microbe interactions and host immunity. The use of simple model systems facilitates addressing generally important questions and testing overarching, therapeutically relevant principles that likely transcend obvious interspecies differences. Here, we evaluate the potential of the freshwater polyp Hydra, to dissect (...) fundamental principles of microbiome regulation by the host, that is the human HF. In particular, we focus on therapeutically targetable host‐microbiome interactions, such as nutrient dependency, microbial interactions and host defence. Offering a new lens into the study of HF – microbiota interactions, we argue that general principles of how Hydra manages its microbiota can inform the development of novel, microbiome‐targeting therapeutic interventions in human skin disease. (shrink)

Meet the Metaorganism is a web‐based learning app that combines three fundamental biological concepts (coevolution, community dynamics, and immune system) with latest scientific findings using the metaorganism as a central case study. In a transdisciplinary team of scientists, information designers, programmers, science communicators, and educators, we conceptualized and developed the app according to the latest didactic and scientific findings and aimed at setting new standards in visual design, digital knowledge transfer, and online education. A content management system allows continuous integration (...) of new findings, which enables us to expand the app with the dynamics of the research field. Students can thus gain a close insight and connection to current research, and at the same time learn that knowledge is not static but grows dynamically. Especially in the realm of the easily accessible metaorganism research, visualization plays an essential role to keep complex processes understandable and memorable. Meet the Metaorganism is freely available online and can be accessed here: www.metaorganism.app. (shrink)

We report on the small-scale (0.5 13 h - 1M, a large-scale bias of ~2.0 and a satellite fraction of 12 ± 2 per cent. Thus, these galaxies occupy haloes with average masses in between those of the higher redshift BOSS CMASS sample and the original SDSS I/II luminous red galaxy sample © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society © doi:10.1093/mnras/sts314.

The evidence compiled in the target article demonstrates that the assumptions of cultural group selection theory are often met, and it is therefore a useful framework for generating plausible hypotheses. However, more can be said about how we can test the predictions of CGS hypotheses against competing explanations using historical, archaeological, and anthropological data.

The biannual international workshop entitled “The diversification of early emerging metazoans: A window into animal evolution?” took place at the Evangelische Akademie Tutzing, Germany, 11–14. September 2017. It was organized by Thomas Bosch (Kiel), Thomas Holstein (Heidelberg), and Ulrich Technau (Vienna), and it was sponsored by the Deutsche Forschungsgemeinschaft (DFG). The meeting gathered over 140 researchers to discuss the contribution of non‐bilaterian metazoan models (Porifera, Ctenophora, Placozoa, and Cnidaria) to our understanding of: a. The evolution of metazoan (...) developmental processes; b. Fundamental molecular mechanisms underlying metazoan features; and c. The complex interactions that animals establish with their environment. (shrink)

This article describes how methodologies of EU-funded research within the life sciences and biomedicine have recently become more gender sensitive. This transformation is the result of the Gender Impact Assessments of the EU Fifth Framework Programme, commissioned in 2000-1. The authors assessed the research programme for life sciences, which includes a large health-related component. The new guidelines for research emphasize the need for clear terminology for concepts of sex and gender and for a distinction to be made between the two, (...) for both life sciences and health research. Attention to possible sex differences, even in preclinical research, as well as to effects of gender, will lead to more adequate research data that serve the health of both men and women. The transformation to research becoming more gender-sensitive is further discussed in the context of feminist theory on the body. Being fully aware of the fact that what is happening in bodies is mediated by particular technologies, the authors make an appeal to invest in concepts that take the living and changing body into account. (shrink)

Increasing complexity of projects is mentioned as one of the reasons for project failure—still. This paper presents a comparative research to investigate how project complexity was perceived by project practitioners in different industry sectors. Five sectors were included: process industry, construction industry, ICT, high-tech product development, and food processing industry. In total, more than 140 projects were included in the research, hence providing a broad view on Dutch project practice. From the complexity assessments, it is concluded that only one complexity (...) element was present in the top complexity elements of projects across the five sectors: the high project schedule drive. The variety of external stakeholders’ perspectives, a lack of resources and skills availability, and interference with existing site were found in the top lists of three sectors. It was concluded that a framework to grasp project complexity could support the management of complex projects by creating awareness for the complexities. Further research could be focused on the subjective character of complexity as well as on the application of cross-sector learning, since this research does show similarities between large technical projects in different sectors. (shrink)

RESUMENEl valor estético del Sistema del Idealismo Trascendental ha pasado algo desapercibido, si se tiene en cuenta su relevancia y si se compara con la buena fortuna de otras obras del mismo autor. La tendencia general, justificada, ha sido estudiar la cuestión de la belleza y el arte en aquellas obras directamente dedicadas a este tema. Este artículo pone en evidencia el valor estético decisivo que tiene el Sistema y, cómo toda la obra y toda su estructura, fundamenta y desarrolla (...) la definición de belleza que aparece sólo en sus últimas líneas: «lo infinito expresado de modo finito es belleza» (SW 465).PALABRAS CLAVESCHELLING, ESTÉTICA, SISTEMA DEL IDEALISMO TRASCENDENTAL, BELLEZAABSTRACTThe aesthetic value of the System of Transcendental Idealism has been scarcely recognized. It must be considered the relevance of this work, and how easy has been the recognition of beauty in other works of Schelling. The general tendency, absolutely justified, has been to look for beauty and art in those text clearly devoted to this topic. In this article it is shown and analyzed the decisive aesthetic value of the System: how the whole work, its whole structure, base and develops the definition of beauty we find just in the last lines of the text: «The infinite expressed in a finite way is beauty» (SW 465)KEYWORDSSCHELLING, AESTHETICS, SYSTEM OF THE TRANSCENDENTAL IDEALISM, BEAUTY. (shrink)

This book is the second of two volumes devoted to the work of Theo Kuipers, a leading Dutch philosopher of science. Philosophers and scientists from all over the world, thirty seven in all, comment on Kuipers’ philosophy, and each of their commentaries is followed by a reply from Kuipers. The present volume is devoted to Kuipers’ neo-classical philosophy of science, as laid down in his Structures in Science . Kuipers defends a dialectical interaction between science and philosophy in that he (...) views philosophy of science as a meta-science which formulates cognitive structures that provide heuristic patterns for actual scientific research, including design research. In addition, Kuipers pays considerable attention to the computational approaches to philosophy of science as well as to the ethics of doing research. Thomas Nickles, David Atkinson, Jean-Paul van Bendegem, Maarten Franssen, Anne Ruth Mackor, Arno Wouters, Erik Weber & Helena de Preester, Eric Scerri, Adam Grobler & Andrzej Wisniewski, Alexander van den Bosch, Gerard Vreeswijk, Jaap Kamps, Paul Thagard, Emma Ruttkamp, Robert Causey, Henk Zandvoort comment on these ideas of Kuipers, and many present their own account. The present book also contains a synopsis of Structures in Science. It can be read independently of the first volume of Essays in Debate with Theo Kuipers, which is devoted to Kuipers’ From Instrumentalism to Constructive Realism. (shrink)

La felicidad es el punto focal de la ética aristotélica: las virtudes, las decisiones, los actos voluntarios; todo se dirige a ella como a un fin. En este artículo analizamos los aspectos que definen ese fin: por qué y cómo la felicidad se convierte en fin último de la existencia humana. Por otro lado, la felicidad pertenece a la vida intelectiva, no a la sensitiva ni nutritiva. Esta naturaleza intelectiva de la felicidad abre el interrogante sobre la dimensión apetitiva o (...) desiderativa en la acción humana y su valoración ética. Todo ello determina un modo de educación moral que es una educación para la felicidad. Estas son las cuestiones que se estudian en este artículo y a las que se responde, principalmente, desde la Ética Nicomaquea. (shrink)

Hannah Arendts politischer Theorie liegt eine relationale Ontologie zugrunde, in der Pluralität und singuläre Freiheit in einem wechselseitigen Bedingungsverhältnis stehen. Das politische Zusammenhandeln setzt freie Individuen voraus, die sich im Netzwerk sozialer Beziehungen differenzieren und identifizieren. Freiheit verwirklicht sich als Partizipation an öffentlicher Verständigung, in der die lebensweltliche Begrenztheit der eigenen Perspektive durch die Auseinandersetzung mit anderen Perspektiven überschritten wird. Darin liegt die kommunikative Basis posttraditioneller politischer Gemeinschaft. Politisches Handeln ist Selbstverwirklichung öffentlicher Beziehungsnetze, die sich als Wir-Identitäten begreifen können. Ebensowenig (...) wie die Individuen stehen die Netzwerke in atomistischer Isolation. Die partikularen politischen Bewegungen sind Teil eines globalen Handlungszusammenhangs. Neben die Pluralität als politischer Leitidee stellt Arendt den integrativen Impuls einer globalen Weltverantwortung. Die partikular-kulturellen Kontexte werden im Sinne der kantischen erweiterten Denkungsart auf einen menschheitlich-universalen Handlungskontext bezogen. Der Perspektivenvielfalt steht eine regulative Universalität der Weltverantwortung gegenüber, die der reflektierenden Urteilskraft überantwortet ist. So verbindet Arendt den republikanischen Partikularismus mit kantisch-universellem Weltbürgertum. (shrink)