Página 1 dos resultados de 52 itens digitais encontrados em 0.022 segundos

A Hyperspace Model to Decipher the Genetic Architecture of Developmental Processes: Allometry Meets Ontogeny

Wu, Rongling; Hou, Wei
Fonte: Copyright © 2006 by the Genetics Society of America Publicador: Copyright © 2006 by the Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em /01/2006 EN
Relevância na Pesquisa
36.15%
To better utilize limited resources for their survival and reproduction, all organisms undergo developmental changes in both body size and shape during ontogeny. The genetic analysis of size change with increasing age, i.e., growth, has received considerable attention in quantitative developmental genetic studies, but the genetic architecture of ontogenetic changes in body shape and its associated allometry have been poorly understood partly due to the lack of analytical tools. In this article, we attempt to construct a multivariate statistical framework for studying the genetic regulation of ontogenetic growth and shape. We have integrated biologically meaningful mathematical functions of growth curves and developmental allometry into the estimation process of genetic mapping aimed at identifying individual quantitative trait loci (QTL) for phenotypic variation. This model defined with high dimensions can characterize the ontogenetic patterns of genetic effects of QTL over the lifetime of an organism and assess the interplay between genetic actions/interactions and phenotypic integration. The closed forms for the residual covariance matrix and its determinant and inverse were derived to overcome the computational complexity typical of our high-dimensional model. We used a worked example to validate the utility of this model. The implications of this model for genetic research of evo–devo are discussed.

A wing expressed sequence tag resource for Bicyclus anynana butterflies, an evo-devo model

Beldade, Patrícia; Rudd, Stephen; Gruber, Jonathan D; Long, Anthony D
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 31/05/2006 EN
Relevância na Pesquisa
36.06%

Whole-mount in situ hybridization in the Rotifer Brachionus plicatilis representing a basal branch of lophotrochozoans

Boell, Louis A.; Bucher, Gregor
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.11%
In order to broaden the comparative scope of evolutionary developmental biology and to refine our picture of animal macroevolution, it is necessary to establish new model organisms, especially from previously underrepresented groups, like the Lophotrochozoa. We have established the culture and protocols for molecular developmental biology in the rotifer species Brachionus plicatilis Müller (Rotifera, Monogononta). Rotifers are nonsegmented animals with enigmatic basal position within the lophotrochozoans and marked by several evolutionary novelties like the wheel organ (corona), the median eye, and the nonpaired posterior foot. The expression of Bp-Pax-6 is shown using whole-mount in situ hybridization. The inexpensive easy culture and experimental tractability of Brachionus as well as the range of interesting questions to which it holds the key make it a promising addition to the “zoo” of evo-devo model organisms.

Neutrality and Robustness in Evo-Devo: Emergence of Lateral Inhibition

Munteanu, Andreea; Solé, Ricard V.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.61%
Embryonic development is defined by the hierarchical dynamical process that translates genetic information (genotype) into a spatial gene expression pattern (phenotype) providing the positional information for the correct unfolding of the organism. The nature and evolutionary implications of genotype–phenotype mapping still remain key topics in evolutionary developmental biology (evo-devo). We have explored here issues of neutrality, robustness, and diversity in evo-devo by means of a simple model of gene regulatory networks. The small size of the system allowed an exhaustive analysis of the entire fitness landscape and the extent of its neutrality. This analysis shows that evolution leads to a class of robust genetic networks with an expression pattern characteristic of lateral inhibition. This class is a repertoire of distinct implementations of this key developmental process, the diversity of which provides valuable clues about its underlying causal principles.

Reptile scale paradigm: Evo-Devo, pattern formation and regeneration

Chang, Cheng; Wu, Ping; Baker, Ruth E.; Maini, Philip K.; Alibardi, Lorenzo; Chuong, Cheng-Ming
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
46.46%
The purpose of this perspective is to highlight the merit of the reptile integument as an experimental model. Reptiles represent the first amniotes. From stem reptiles, extant reptiles, birds and mammals have evolved. Mammal hairs and feathers evolved from Therapsid and Sauropsid reptiles, respectively. The early reptilian integument had to adapt to the challenges of terrestrial life, developing a multi-layered stratum corneum capable of barrier function and ultraviolet protection. For better mechanical protection, diverse reptilian scale types have evolved. The evolution of endothermy has driven the convergent evolution of hair and feather follicles: both form multiple localized growth units with stem cells and transient amplifying cells protected in the proximal follicle. This topological arrangement allows them to elongate, molt and regenerate without structural constraints. Another unique feature of reptile skin is the exquisite arrangement of scales and pigment patterns, making them testable models for mechanisms of pattern formation. Since they face the constant threat of damage on land, different strategies were developed to accommodate skin homeostasis and regeneration. Temporally, they can be under continuous renewal or sloughing cycles. Spatially...

The importance of living botanical collections for plant biology and the “next generation” of evo-devo research

Dosmann, Michael; Groover, Andrew
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 22/06/2012 EN
Relevância na Pesquisa
46.8%
Living botanical collections include germplasm repositories, long-term experimental plantings, and botanical gardens. We present here a series of vignettes to illustrate the central role that living collections have played in plant biology research, including evo-devo research. Looking toward the future, living collections will become increasingly important in support of future evo-devo research. The driving force behind this trend is nucleic acid sequencing technologies, which are rapidly becoming more powerful and cost-effective, and which can be applied to virtually any species. This allows for more extensive sampling, including non-model organisms with unique biological features and plants from diverse phylogenetic positions. Importantly, a major challenge for sequencing-based evo-devo research is to identify, access, and propagate appropriate plant materials. We use a vignette of the ongoing 1,000 Transcriptomes project as an example of the challenges faced by such projects. We conclude by identifying some of the pinch points likely to be encountered by future evo-devo researchers, and how living collections can help address them.

Emerging model systems in evo-devo: cavefish and microevolution of development

Jeffery, William R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
36.11%
Cavefish and their conspecific surface-dwelling ancestors (Astyanax mexicanus) are emerging as a model system to study the microevolution of development. Here we describe attributes that make this system highly promising for such studies. We review how the Astyanax system is being used to understand evolutionary forces underlying loss of eyes and pigmentation in cavefish. Pigment regression is probably explained by neutral mutations, whereas natural selection is a likely mechanism for loss of eyes. Finally, we discuss several research frontiers in which Astyanax is poised to make significant contributions in the future: evolution of constructive traits, the craniofacial skeleton, the central nervous system, and behavior.

Flower color as a model system for studies of plant evo-devo

Sobel, James M.; Streisfeld, Matthew A.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 20/08/2013 EN
Relevância na Pesquisa
46.65%
Even though pigmentation traits have had substantial impacts on the field of animal evolutionary developmental biology, they have played only relatively minor roles in plant evo-devo. This is surprising given the often direct connection between flower color and fitness variation mediated through the effects of pollinators. At the same time, ecological and evolutionary genetic studies have utilized the molecular resources available for the anthocyanin pathway to generate several examples of the molecular basis of putatively adaptive transitions in flower color. Despite this opportunity to synthesize experimental approaches in ecology, evolution, and developmental biology, the investigation of many fundamental questions in evo-devo using this powerful model is only at its earliest stages. For example, a long-standing question is whether predictable genetic changes accompany the repeated evolution of a trait. Due to the conserved nature of the biochemical and regulatory control of anthocyanin biosynthesis, it has become possible to determine whether, and under what circumstances, different types of mutations responsible for flower color variation are preferentially targeted by natural selection. In addition, because plants use anthocyanin and related compounds in vegetative tissue for other important physiological functions...

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo

Lapraz, François; Rawlinson, Kate A; Girstmair, Johannes; Tomiczek, Bartłomiej; Berger, Jürgen; Jékely, Gáspár; Telford, Maximilian J; Egger, Bernhard
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 09/10/2013 EN
Relevância na Pesquisa
56.46%
Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research.

An explanatory evo-devo model for the developmental hourglass

Akhshabi, Saamer; Sarda, Shrutii; Dovrolis, Constantine; Yi, Soojin
Fonte: F1000Research Publicador: F1000Research
Tipo: Artigo de Revista Científica
Publicado em 08/07/2014 EN
Relevância na Pesquisa
46.14%
The "developmental hourglass' describes a pattern of increasing morphological divergence towards earlier and later embryonic development, separated by a period of significant conservation across distant species (the "phylotypic stage'). Recent studies have found evidence in support of the hourglass effect at the genomic level. For instance, the phylotypic stage expresses the oldest and most conserved transcriptomes. However, the regulatory mechanism that causes the hourglass pattern remains an open question. Here, we use an evolutionary model of regulatory gene interactions during development to identify the conditions under which the hourglass effect can emerge in a general setting. The model focuses on the hierarchical gene regulatory network that controls the developmental process, and on the evolution of a population under random perturbations in the structure of that network. The model predicts, under fairly general assumptions, the emergence of an hourglass pattern in the structure of a temporal representation of the underlying gene regulatory network. The evolutionary age of the corresponding genes also follows an hourglass pattern, with the oldest genes concentrated at the hourglass waist. The key behind the hourglass effect is that developmental regulators should have an increasingly specific function as development progresses. Analysis of developmental gene expression profiles from Drosophila melanogaster and Arabidopsis thaliana provide consistent results with our theoretical predictions.

A Developmental Staging Series for the Lizard Genus Anolis: A New System for the Integration of Evolution, Development, and Ecology

Sanger, Thomas J.; Gibson-Brown, Jeremy J.; Losos, Jonathan
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
EN_US
Relevância na Pesquisa
36.14%
Vertebrate developmental biologists typically rely on a limited number of model organisms to understand the evolutionary bases of morphological change. Unfortunately, a typical model system for squamates (lizards and snakes) has not yet been developed leaving many fundamental questions about morphological evolution unaddressed. New model systems would ideally include clades, rather than single species, that are amenable to both laboratory studies of development and field-based analyses of ecology and evolution. Combining an understanding of development with an understanding of ecology and evolution within and between closely related species has the potential to create a seamless understanding of how genetic variation underlies ecologically and evolutionarily relevant variation within populations and between species. Here we briefly introduce a new model system for the integration of development, evolution, and ecology, the lizard genus Anolis, a diverse group of lizards whose ecology and evolution is well understood, and whose genome has recently been sequenced. We present a developmental staging series for Anolis lizards that can act as a baseline for later comparative and experimental studies within this genus.; Organismic and Evolutionary Biology

Gene Expression Studies on the Evolution of Development and Innate Immunity in the Nematode Pristionchus pacificus; Genexpressions-Studien zur Evolution der Entwicklung und Angeborenen Immunität des Nematoden Pristionchus pacificus

Sinha, Amit
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
36.11%
Evolutionary biology aims to explain the enormous biological diversity by employing diverse approaches including systematics, ecology, population genetics and developmental biology. Comparison of a set of traits across different species is a very fruitful approach in evolutionary biology. With this goal in mind, the nematode Pristionchus pacificus has been developed as a model system for comparative analysis vis-a-vis the extensively studied nematode model Caenorhabditis elegans, and serves to integrate insights from developmental biology, ecology and population genetics. Comparison of processes such as vulva development, sex-determination pathways, gonad development and developmental polyphenisms such as dauer development and mouth-form dimorphism has revealed that highly conserved genetic pathways can be used in different configurations to generate macroevolutionary changes. The sequencing of the whole genome of P. pacificus opened a new avenue for comparative genomics, e.g. it has a larger genome and a higher gene content than C. elegans. Many factors contribute to this increase in gene number, including expansion of certain gene families, horizontal gene transfer, and origin of lineage specific pioneer' genes, many of which might have a potential role in its ecological adaptations related to beetle association. However...

A stranger in a strange land: the utility and interpretation of heterologous expression

Kramer, Elena M.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.11%
One of the major goals of the modern study of evodevo is to understand the evolution of gene function across a range of contexts, including sub/neofunctionalization, co-option of genetic modules, and the evolution of morphological novelty. To these ends, comparative studies of gene expression can be useful for constructing hypotheses, but cannot provide direct evidence of functional evolution. Unfortunately, determining endogenous gene function in non-model species is often not an option. Faced with this dilemma, a common approach is to use heterologous expression (HE) in genetically tractable model species as a proxy for functional analyses. Such experiments have important limitations, however, and require caution in the interpretation of their results. How do we dissociate biochemical function from its original genomic context? In the end, what does HE actually tell us? Here, I argue that HE only sheds light on specific types of biochemical conservation, but can be useful when experiments are carefully interpreted.

A stranger in a strange land: the utility and interpretation of heterologous expression

Kramer, Elena M.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.11%
One of the major goals of the modern study of evodevo is to understand the evolution of gene function across a range of contexts, including sub/neofunctionalization, co-option of genetic modules, and the evolution of morphological novelty. To these ends, comparative studies of gene expression can be useful for constructing hypotheses, but cannot provide direct evidence of functional evolution. Unfortunately, determining endogenous gene function in non-model species is often not an option. Faced with this dilemma, a common approach is to use heterologous expression (HE) in genetically tractable model species as a proxy for functional analyses. Such experiments have important limitations, however, and require caution in the interpretation of their results. How do we dissociate biochemical function from its original genomic context? In the end, what does HE actually tell us? Here, I argue that HE only sheds light on specific types of biochemical conservation, but can be useful when experiments are carefully interpreted.

Comparative Transcriptomes and EVO-DEVO Studies Depending on Next Generation Sequencing

Liu, Tiancheng; Yu, Lin; Liu, Lei; Li, Hong; Li, Yixue
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.79%
High throughput technology has prompted the progressive omics studies, including genomics and transcriptomics. We have reviewed the improvement of comparative omic studies, which are attributed to the high throughput measurement of next generation sequencing technology. Comparative genomics have been successfully applied to evolution analysis while comparative transcriptomics are adopted in comparison of expression profile from two subjects by differential expression or differential coexpression, which enables their application in evolutionary developmental biology (EVO-DEVO) studies. EVO-DEVO studies focus on the evolutionary pressure affecting the morphogenesis of development and previous works have been conducted to illustrate the most conserved stages during embryonic development. Old measurements of these studies are based on the morphological similarity from macro view and new technology enables the micro detection of similarity in molecular mechanism. Evolutionary model of embryo development, which includes the “funnel-like” model and the “hourglass” model, has been evaluated by combination of these new comparative transcriptomic methods with prior comparative genomic information. Although the technology has promoted the EVO-DEVO studies into a new era...

An explanatory evo-devo model for the developmental hourglass

Akhshabi, Saamer; Sarda, Shrutii; Dovrolis, Constantine; Yi, Soojin
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.14%
The "developmental hourglass" describes a pattern of increasing morphological divergence towards earlier and later embryonic development, separated by a period of significant conservation across distant species (the "phylotypic stage"). Recent studies have found evidence in support of the hourglass effect at the genomic level. For instance, the phylotypic stage expresses the oldest and most conserved transcriptomes. However, the regulatory mechanism that causes the hourglass pattern remains an open question. Here, we use an evolutionary model of regulatory gene interactions during development to identify the conditions under which the hourglass effect can emerge in a general setting. The model focuses on the hierarchical gene regulatory network that controls the developmental process, and on the evolution of a population under random perturbations in the structure of that network. The model predicts, under fairly general assumptions, the emergence of an hourglass pattern in the structure of a temporal representation of the underlying gene regulatory network. The evolutionary age of the corresponding genes also follows an hourglass pattern, with the oldest genes concentrated at the hourglass waist. The key behind the hourglass effect is that developmental regulators should have an increasingly specific function as development progresses. Analysis of developmental gene expression profiles from Drosophila melanogaster and Arabidopsis thaliana provide consistent results with our theoretical predictions.

Epigenetic Tracking: a model for all biology

Fontana, Alessandro
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.17%
"Epigenetic Tracking" is a model of systems of biological cells, able to generate arbitrary 2 or 3-dimensional cellular shapes of any kind and complexity (in terms of number of cells, number of colours, etc.) starting from a single cell. If the complexity of such structures is interpreted as a metaphor for the complexity of biological structures, we can conclude that this model has the potential to generate the complexity typical of living beings. It can be shown how the model is able to reproduce a simplified version of key biological phenomena such as development, the presence of "junk DNA", the phenomenon of ageing and the process of carcinogenesis. The model links properties and behaviour of genes and cells to properties and behaviour of the organism, describing and interpreting the said phenomena with a unified framework: for this reason, we think it can be proposed as a model for all biology. The material contained in this work is not new: the model and its implications have all been described in previous works from a computer-science point of view. This work has two objectives: 1) To present the whole theory in an organic and structured way and 2) To introduce Epigenetic Tracking from a biological perspective. The work is divided into six parts: the first part is the introduction; the second part describes the cellular model; the third part is dedicated to the evo-devo method and transposable-elements; the fourth part deals with junk DNA and ageing; the fifth part explores the topic of cancer; the sixth part draws the conclusions.; Comment: 42 pages...

Adaptive walks in a gene network model of morphogenesis: insights into the Cambrian explosion

Sole, Ricard V.; Fernandez, Pau; Kauffman, Stuart A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/11/2003
Relevância na Pesquisa
36.11%
The emergence of complex patterns of organization close to the Cambrian boundary is known to have happened over a (geologically) short period of time. It involved the rapid diversification of body plans and stands as one of the major transitions in evolution. How it took place is a controversial issue. Here we explore this problem by considering a simple model of pattern formation in multicellular organisms. By modeling gene network-based morphogenesis and its evolution through adaptive walks, we explore the question of how combinatorial explosions might have been actually involved in the Cambrian event. Here we show that a small amount of genetic complexity including both gene regulation and cell-cell signaling allows one to generate an extraordinary repertoire of stable spatial patterns of gene expression compatible with observed anteroposterior patterns in early development of metazoans. The consequences for the understanding of the tempo and mode of the Cambrian event are outlined.; Comment: to appear in International Journal of Developmental Biology, special issue on Evo-Devo (2003)

Appendage development and early Distal-less regulation in arthropods: A study of the chelicerate Tetranychus urticae (Acarida)

Cyrus-Kent, Chlo?
Fonte: University of Cambridge; Department of Zoology; School of Biological Sciences; Corpus Christi College Publicador: University of Cambridge; Department of Zoology; School of Biological Sciences; Corpus Christi College
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.13%
A major goal of evolutionary developmental biology is to explore mechanisms and events underlying evolution of the myriad body plan morphologies expressed both genetically and phenotypically within the animal kingdom. Arthropods exhibit an astounding array of morphological diversity both within and between representative sub-phyla, thus providing an ideal phylum through which to address questions of body plan innovation and diversification. Major arthropod groups are recognised and defined by the distinct form and number of articulated appendages present along the antero-posterior axis of their segmented bodies. A great deal is known about the developmental genetics of limb development in the model insect Drosophila melanogaster, added to which, much comparative gene expression data and a growing body of functional genetic data is emerging for other arthropod species. Arthropod limb primordia are consistently marked by expression of the homeobox gene Distal-less (Dll), and the focus of this thesis is to compare signalling mediated by early Dll regulatory genes activity along antero-posterior and dorso-ventral embryonic axes during limb specification in Drosophila, with the activity of their orthologs in the widely disparate chelicerate...

The mechanisms underlying convergent evolution in the plumage patterns of birds

Gluckman, Thanh-Lan
Fonte: Elsevier - Animal Behaviour; University of Cambridge; Department of Zoology Publicador: Elsevier - Animal Behaviour; University of Cambridge; Department of Zoology
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.11%
This thesis is embargoed until 2017-01 for publication reasons; Convergent evolution is a central theme in biology. Birds are an ideal system to examine the mechanisms underlying convergent evolution. Although bird patterning is diverse, within-feather patterns have repeatedly converged on the same four types: mottled patterns, scales, bars and spots. Other avian patterns occur, e.g. stripes, but are rare. In my thesis I examine the four main mechanisms underlying convergent evolution in plumage patterns: evolutionary genetics, evolutionary development, natural selection for signaling and camouflage. Japanese quail (Coturnix japonica) is a model system in developmental biology. Examining the developmental basis of pattern formation using molecular techniques, the dorsal patterning of embryonic quail is likely due to activation of the melanocortin-1 receptor, which is a highly conserved pathway in vertebrates. I examined whether a reaction-diffusion based theoretical model of pattern formation may predict developmental constraint in two groups that have different lifestyles and spectacular patterns: waterfowl (Anseriformes) and gamebirds (Galliformes). Tracing the evolutionary trajectory of pattern evolution with Bayesian comparative modeling there was evidence for developmental constraint in pattern evolution. Adaptive explanations may also result in convergence. Cuckoo-hawk mimicry has been demonstrated in the common cuckoo (Cuculus canorus) and the Eurasian sparrowhawk (Accipiter nisus)...