Secreted signaling molecules act as morphogens to control patterning and growth in many developing tissues. Since locally produced morphogens spread to form a concentration gradient in the surrounding tissue, spreading is generally thought to be the key step in the non‐autonomous actions. Here, we review recent advances in tool development to investigate morphogen function using the role of decapentaplegic (Dpp)/bone morphogenetic protein (BMP)‐type ligand in the Drosophila wing disc as an example. By applying protein binder tools to distinguish between (...) the roles of Dpp spreading and local Dpp signaling, we found that Dpp signaling in the source cells is important for wing patterning and growth but Dpp spreading from this source cells is not as strictly required as previously thought. Given recent studies showing unexpected requirements of long‐range action of different morphogens, manipulating endogenous morphogen gradients by synthetic protein binder tools could shed more light on how morphogens act in developing tissues. (shrink)

Understanding how and why practices may be transformed is vital for any transition towards socio-environmental sustainability. However, theorising and explaining the role of individual agency in practice change continues to present challenges. In this paper we propose that theories of practice can be usefully combined with a psychosocial framework to explain how agency is biographically patterned and how this patterning is a product of attachment relationships and emergent strategies for dealing with uncertainty. Biographical interview data from the project Energy (...) Biographies is used to illustrate the ways in which this theoretical approach can enhance understanding of how potential for practice change may be opened up or obstructed. (shrink)

We propose a model mechanism for the initiation and spatial positioning of teeth primordia in the alligator, Alligator mississippiensis. Detailed embryological studies by Westergaard and Ferguson have shown that jaw growth plays a crucial role in the developmental patterning of the tooth initiation process. Based on biological data we develop a dynamic patterning mechanism, which crucially includes domain growth. The mechanism can reproduce the spatial pattern development of the first seven teeth primordia in each half jaw of A. (...) mississippiensis. The results for the precise spatio-temporal sequence compare well with experiment. Simulation of the model also predicts that certain transplantations can alter the spatial sequence of teeth primordia initiation. (shrink)

The Drosophila embryo provides a useful model system to study the mechanisms that lead to pattern and cell diversity in the central nervous system (CNS). The Drosophila CNS, which encompasses the brain and the ventral nerve cord, develops from a bilaterally symmetrical neuroectoderm, which gives rise to neural stem cells, called neuroblasts. The structure of the embryonic ventral nerve cord is relatively simple, consisting of a sequence of repeated segmental units (neuromeres), and the mechanisms controlling the formation and specification of (...) the neuroblasts that form these neuromeres are quite well understood. Owing to the much higher complexity and hidden segmental organization of the brain, our understanding of its development is still rudimentary. Recent investigations on the expression and function of proneural genes, segmentation genes, dorsoventral‐patterning genes and a number of other genes have provided new insight into the principles of neuroblast formation and patterning during embryonic development of the fly brain. Comparisons with the same processes in the trunk help us to understand what makes the brain different from the ventral nerve cord. Several parallels in early brain patterning between the fly and the vertebrate systems have become evident. BioEssays 26:739–751, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Two general features of metameric patterning in Drosophilaare considered: (1) maintenance of a constant number of metameres (segments or parasegments) in the face of variation in length of the embryo; (2) expression of pattern by on‐off switchings of particular genes, with only three or four rows of cells to each element of pattern. For each of these features, the general strategic question is raised: could reaction‐diffusion theory account for this? In both cases, it is answered affirmatively. For the second (...) feature, this review contains some hitherto unpublished computer simulations by one of us (K. Y. T.), illustrating that a reaction‐diffusion mechanism can be transformed into a patterned switching mechanism by nothing more than compartmenting of the diffusion region. For the scale of three compartments to one pattern repeat unit (representing three rows of cells to a segment) the switching pattern predicted by computation is two‐off to one‐on. This resembles the pattern of expression of the engrailed gene, posteriorly localized in each segment. (shrink)

Two major works in recent evolutionary biology have in different ways touched upon the issue of cultural replicators in language, namely Dawkins’ Selfish Gene and Maynard Smith and Szathmáry’s Major Transitions in Evolution. In the latter, the emergence of language is referred to as the last major transition in evolution, a claim we argue to be derived from a crucial property of language, called Duality of Patterning. Prima facie, this property makes natural language look like a structural equivalent to (...) DNA, and its peer in terms of expressive power. We will argue that, if one takes seriously Maynard Smith and Szathmáry’s outlook and examines what has been proposed as linguistic replicators, amongst others phonemes and words, the analogy meme-gene becomes problematic. A key issue is the fact that genes and memes are assumed to carry and transmit information, while what has been described as the best candidate for replicatorhood in language, i.e. the phoneme, does by definition not carry meaning. We will argue that semiotic systems with Duality of Pattering force us to reconsider either the analogy between replicators in the biological and the cultural domain, or what it is to be a replicator in linguistics. (shrink)

Construction of the trunk/caudal region of the vertebrate embryo involves a set of distinct molecules and processes whose relationships are just coming into focus. In addition to the subdivision of the embryo into head and trunk domains, this “caudalisation” process requires the establishment and maintenance of a stem zone. This sequentially generates caudal tissues over a long period which then undergo differentiation and patterning in the extending body axis. Here we review recent studies that show that changes in the (...) signalling properties of the paraxial mesoderm act as a switch that controls onset of differentiation and pattern in the spinal cord. These findings identify distinct roles for different caudalising factors; in particular, Fibroblast Growth Factor (FGF) inhibits differentiation in the caudal stem zone, while Retinoic acid (RA) provided rostrally by somitic mesoderm is required for neuronal differentiation and establishment of ventral neural pattern. Furthermore, the mutual opposition of FGF and RA pathways controls not only neural differentiation but also mesoderm segmentation and might also underlie the progressive assignment of rostrocaudal identity by regulating Hox gene availability and activation. BioEssays 26:857–869, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Disruption of Nodal in the lateral plate mesoderm (LPM) usually leads to left‐right (LR) patterning defects in multiple organs. However, whether the LR patterning of organs is always regulated in a coupled way has largely not yet been elucidated. In addition, whether other crucial regulators exist in the LPM that coordinate with Nodal in regulating organ LR patterning is also undetermined. In this paper, after briefly summarizing the common process of LR patterning, the most puzzling question (...) regarding the initiation of asymmetry is considered and the divergent mechanisms underlying the uncoupled LR patterning in different organs are discussed. On the basis of cases in which different organ LR patterning is determined in an uncoupled way via an independent mechanism or at a different time, we propose that there are other critical factors in the LPM that coordinate with Nodal to regulate heart LR asymmetry patterning during early LR patterning.Also watch the Video Abstract. (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)

The complex organization of syntax in hierarchical structures is one of the core design features of human language. Duality of patterning refers, for instance, to the organization of the meaningful elements in a language at two distinct levels: a combinatorial level, where meaningless forms are combined into meaningful forms; and a compositional level, where meaningful forms are composed into larger lexical units. The question remains wide open regarding how such structures could have emerged. The aim of this paper is (...) to address these two aspects in a self-consistent way. First, we introduce suitable measures to quantify the level of combinatoriality and compositionality in a language, and we present a framework to estimate these observables in human natural languages. Second, we show that a recently introduced multi-agent modeling scheme, namely the Blending Game, provides a mathematical framework to address the problem of how a population of individuals can bootstrap combinatoriality and compositionality. Theoretical predictions based on this model turn out to be in good agreement with empirical data. It is remarkable that the two sides of duality of patterning emerge simultaneously as a consequence of a pure cultural dynamics in a simulated environment that contains meaningful relations, provided a simple constraint on message transmission fidelity is also considered. (shrink)

In a series of works, different models have shed light on the acoustic properties of air sacs, an organ located in the laryngeal region that is present in all great apes with the exception of humans. These works have shown how the loss of air sacs expands the number of possible digits but not the amount of signals per se. The number of signals in human language increased when the codifying property known as duality of patterning became characteristic of (...) the codifying system, allowing digits to be combined in order for new signals to be codified. A direct relationship between air sacs and duality is presently being plotted, integrating linguistic theory and data from computational models into an evolutionary and developmental perspective of the evolution of modern speech. (shrink)

Genetic analysis of Drosophila has shown that a morphogenetic gradient of the Transforming Growth Factor‐β family member dpp patterns the embryonic dorsalventral axis. Molecular and embryological evidence from Xenopus has strongly suggested a similar role for Bmp‐4, the dpp homolog, in patterning the dorsalventral axis of chordates. A recent report has now identified mutations in two genes, dino and swirl, that disrupt dorsal‐ventral patterning in the zebrafish Danio rerio(1). Characterization of these mutations parallels findings from Drosophila, thus establishing (...) a genetic framework for the analysis of dorsalventral patterning in a vertebrate. (shrink)

The agro-pastoral ecotone, an ecological transition zone connecting adjacent areas of agricultural planting area and grassland animal husbandry, has three features: a complex natural condition, relatively pronounced population pressure, and a fragile ecological environment. In this study, we conducted an ecosystem risk assessment in the western part of Jilin Province, China, based on multiscale and multitemporal remote sensing images and land-use data. Furthermore, we focused on land-use change from 1995 to 2015 by applying the dynamic change information survey method and (...) carrying out a transfer track analysis. The results revealed three main findings. The ecological risk index at the scale of 3 km × 3 km harbors significant spatial correlation. The ecological risk index of unutilized land, forest land, and grassland is relatively high for each, and their anti-interference ability is weak, while the ecological risk index of construction land and water area is the lowest. Human interference, e.g., construction activities and cultivated land occupation, is the leading factor driving the exacerbation of ecological risk and frequent land-use type conversions. At the study period’s end, a trend of slight contraction in the high-risk areas was found, indicating that land-use regulation and land protection policies have had significantly positive impact upon the lands’ ecological value. The overall study identified a reasonable research scale for eco-environmental risk assessment and discerned relationships between regional land-use changes through geospatial analysis. Moreover, our findings can help provide practical case study information applicable to similar regions with agro-pastoral ecotones. (shrink)

Pregnancy is thought to be a metabolically very expensive endeavor, yet investigations have produced inconsistent results concerning the responsiveness of human birth weight to maternal nutritional stress or nutritional intervention. These findings have led some researchers to conclude that fetal growth is strongly buffered against fluctuations in maternal energy balance, making the fetus in effect a “nearly perfect parasite.” This buffering would appear to be a reasonable adaptive response given the high risk of morbidity and mortality associated with low birth (...) weight. However, a life-history approach leads to the prediction that maternal investment strategies in pregnancy should be geared toward maximizing lifetime reproductive success rather than simply the success of the current pregnancy, and by extension that maternal investment strategies should vary with reproductive value. The physiology of human pregnancy in fact appears to include a number of mechanisms that protect maternal energy resources from diversion to the fetus and preserve them for future reproductive events. These mechanisms include adjustment of blood flow to the uterus and perhaps minor adjustments in gestation length, although evidence for the latter is scant. Suggestions are made for ways of investigating these maternal options. (shrink)

Selecting a large and diverse sample of 5–6-year-old preschool children, we aimed to extend previous findings on variability in children’s home math environment and its association with children’s mathematical skills. We operationalized mathematics in a broader way than in previous studies, by considering not only children’s numerical skills but also their patterning skills as integral components of early mathematical development. We investigated the effects of children’s gender and socioeconomic status on their home math environment, examined the associations between children’s (...) home math environment and their mathematical skills, and verified whether these associations were moderated by children’s gender and/or SES. Parents of 353 children completed a home math environment questionnaire and all children completed measures of their numerical and patterning skills. Results indicated no effect of children’s gender on their home math environment. There was no effect of SES on the performed home math activities, but small SES differences existed in parents’ math-related expectations and their attitudes. We found no evidence for associations between children’s home math environment and their mathematical skills. Furthermore, there were no moderating effects of gender or SES on these associations. One explanation for these findings might relate to the characteristics of the general preschool system in the country of the present study. Future studies should consider the effect of the preschool learning environment because it might explain differences between studies and countries with regard to the home math environment and its association with mathematical skills. (shrink)

Current phylogenies show that paired fins and limbs are unique to jawed vertebrates and their immediate ancestry. Such fins evolved first as a single pair extending from an anterior location, and later stabilized as two pairs at pectoral and pelvic levels. Fin number, identity, and position are therefore key issues in vertebrate developmental evolution. Localization of the AP levels at which developmental signals initiate outgrowth from the body wall may be determined by Hox gene expression patterns along the lateral plate (...) mesoderm. This regionalization appears to be regulated independently of that in the paraxial mesoderm and axial skeleton. When combined with current hypotheses of Hox gene phylogenetic and functional diversity, these data suggest a new model of fin/limb developmental evolution. This coordinates body wall regions of outgrowth with primitive boundaries established in the gut, as well as the fundamental nonequivalence of pectoral and pelvic structures. BioEssays 20:371–381, 1998. © 1998 John Wiley & Sons Inc. (shrink)

Embryogenesis involves biochemical patterning as well as mechanical morphogenetic movements, both regulated by the expression of the regulatory genes of development. The reciprocal interplay of morphogenetic movements with developmental gene expression is becoming an increasingly intense subject of investigation. The molecular processes through which differentiation patterning closely regulates the development of morphogenetic movements are today becoming well understood. Conversely, experimental evidence recently revealed the involvement of mechanical cues due to morphogenetic movements in activating mechano-transduction pathways that control both (...) the differentiation and the active morphogenesis of fundamental events in embryonic tissue development. Here I will first focus on the central role the shape of biological structures of the molecular and mesoscopic cell scales plays in mechano-transduction. Then, after a short description of the genetic regulation of the Drosophila embryo mesoderm invagination at gastrulation—one of the best-understood morphogenetic movement of embryogenesis—I will detail the processes of differentiation and of active morphogenesis of Drosophila embryo gastrulation, which require mechano-transduction. Finally, I will explore the putative consequences in evolution of these mechano-transduction events. I speculate that the first ancient multicellular organisms might have emerged from primary morphological and differentiation patterns induced by primitive mechano-sensation effects allowed by mechano-transduction in response to their physical environment, such as touch by gravity or water flows, which might have acted as primitive motor–sensorial systems, thus conditioning the emergence of our primary animal ancestors. (shrink)

This book analyzes--in terms of branching--the pervasive reorganization of Latin syntactic and morphological structures: in the development from Latin to French, a shift can be observed from the archaic, left-branching structures (which Latin inherited from Proto-Indo-European) to modern right-branching equivalents. Brigitte Bauer presents a detailed analysis of this development based on the theoretical discussion and definition of "branching" and "head." Subsequently she relates the diachronic shift to psycholinguistic evidence, arguing that the difficuly of LB complex structures as reflected in their (...) painstaking and delayed acquisition accounts for the extensive typological shift from left to right branching that took place in Latin/French and the other Indo-European languages. (shrink)