搜索结果：Current topics in developmental biology

BACKGROUND: Activins are members of the pleiotrophic family of the transforming growth factor-beta (TGF-β) superfamily of cytokines, initially isolated for their capacity to induce the release of FSH from pituitary extracts. Subsequent research has demonstrated that activins are involved in multiple biological functions including the control of inflammation, fibrosis, developmental biology and tumourigenesis. This review summarizes the current knowledge on the roles of activin in reproductive and developmental biology. It also discusses interesting advances in the field of modulating the bioactivity of activins as a therapeutic target, which would undoubtedly be beneficial for patients with reproductive pathology. METHODS: A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies in the English language which have contributed to the advancement of the field of activin biology, since its initial isolation in 1987 until July 2015. 'Activin', 'testis', 'ovary', 'embryonic development' and 'therapeutic targets' were used as the keywords in combination with other search phrases relevant to the topic of activin biology. RESULTS: Activins, which are dimers of inhibin β subunits, act via a classical TGF-β signalling pathway. The bioactivity of activin is regulated by two endogenous inhibitors, inhibin and follistatin. Activin is a major regulator of testicular and ovarian development. In the ovary, activin A promotes oocyte maturation and regulates granulosa cell steroidogenesis. It is also essential in endometrial repair following menstruation, decidualization and maintaining pregnancy. Dysregulation of the activin-follistatin-inhibin system leads to disorders of female reproduction and pregnancy, including polycystic ovary syndrome, ectopic pregnancy, miscarriage, fetal growth restriction, gestational diabetes, pre-eclampsia and pre-term birth. Moreover, a rise in serum activin A, accompanied by elevated FSH, is characteristic of female reproductive aging. In the male, activin A is an autocrine and paracrine modulator of germ cell development and Sertoli cell proliferation. Disruption of normal activin signalling is characteristic of many tumours affecting reproductive organs, including endometrial carcinoma, cervical cancer, testicular and ovarian cancer as well as prostate cancer. While activin A and B aid the progression of many tumours of the reproductive organs, activin C acts as a tumour suppressor. Activins are important in embryonic induction, morphogenesis of branched glandular organs, development of limbs and nervous system, craniofacial and dental development and morphogenesis of the Wolffian duct. CONCLUSIONS: The field of activin biology has advanced considerably since its initial discovery as an FSH stimulating agent. Now, activin is well known as a growth factor and cytokine that regulates many aspects of reproductive biology, developmental biology and also inflammation and immunological mechanisms. Current research provides evidence for novel roles of activins in maintaining the structure and function of reproductive and other organ systems. The fact that activin A is elevated both locally as well as systemically in major disorders of the reproductive system makes it an important biomarker. Given the established role of activin A as a pro-inflammatory and pro-fibrotic agent, studies of its involvement in disorders of reproduction resulting from these processes should be examined. Follistatin, as a key regulator of the biological actions of activin, should be evaluated as a therapeutic agent in conditions where activin A overexpression is established as a contributing factor.

The alpha and beta keratins are found as 10-nm and 3-nm cytoplasmic filaments, respectively. While the alpha keratins are produced in essentially all vertebrate epithelia (Franke et al.: Exp. Cell Res., 116:429-445, 1978; Sun et al.: Proc. Natl. Acad. Sci. USA, 76:2813-2817, 1979), the beta keratins have been demonstrated only in specific epithelial tissues of birds and reptiles (Sawyer et al.: In: Biology of the Integument: Vertebrates. J. Bereiter-Hahn, A.G. Matoltsy, and K.S. Richards, eds. Springer-Verlag, Berlin, Vol. 2, pp. 194-238, 1986; Landmann: In: Biology of the Integument: Vertebrates. J. Bereiter-Hahn, A.G. Matoltsy, and K.S. Richards, eds. Springer-Verlag, Berlin, Vol. 2, pp. 150-187, 1986). Recently, Homberger and Brush (Zoomorphology, 106:103-114, 1986) have demonstrated that within the lingual epithelium of parrots, beta keratins are expressed exclusively in the anterior ventral region. While it is well established that epidermal-dermal interactions are important for the regional expression of the beta keratin genes in the avian scutate scales and feathers, little is known about the expression of beta keratins in other epithelial structures such as the tongue. We have used biochemical and immunocytochemical techniques to analyze the alpha and beta keratins of the lingual epithelium of the chick as an initial step in the characterization of this model system for developmental studies. We have found that alpha keratins are present throughout the lingual epithelium. The anterior ventral epithelium contains alpha keratin polypeptides characteristic of skin-type differentiation, while the epithelium of the dorsal and posterior ventral regions contains alpha keratin polypeptides characteristic of esophageal-type differentiation (O'Guin et al.: In: Current Topics in Developmental Biology: The Molecular and Developmental Biology of Keratins. A.A. Moscona and A. Monroy, eds. R.H. Sawyer, vol. ed. Academic Press, New York, Vol. 22, pp. 282-306, 1987). Beta keratins are produced only in the differentiated epithelial cells of the anterior ventral region of the tongue. Immunoelectron microscopy demonstrates that the alpha and beta keratins of the stratum intermedium and corneum of the anterior ventral region are found together in the large filament bundles characteristic of this region. The preexistence of the alpha keratins in the cells destined to produce beta keratins as well as the colocalization of these keratins in the filament bundles of these cells suggests that a functional relationship may exist between the alpha and beta keratins.

By William C. Dickison. 544 pages. San Diego, CA, USA: Harcourt Academic Press, 2000. $69.95 h/b. ISBN 0 12 215170 4 These days, when molecular biology, and functional genomics in particular, seem to dominate the whole of plant biology, and when traditional botanical areas no longer form part of most plant science degrees, any new book on plant anatomy is unlikely to be regarded as particularly topical. However, the stock in trade of molecular biologists is mutants, whether natural or induced, or novel genotypes resulting from expression of transgenes. These often display modifications in developmental processes, which result in morphological and anatomical modifications to the body of the plant. An understanding of plant anatomy and how this integrates with physiology, development, ecology, genetics and systematics should therefore be highly pertinent and this book provides an up-to-date account of current thinking in these areas. The first four chapters cover the anatomical foundation of the primary and secondary plant body, providing an overview of organization and structure; subsequent chapters deal with specialized topics in some detail, including evolutionary, physiological and ecological plant anatomy and macromorphology. The author gives numerous interesting examples in which studies of applied plant anatomy have resulted in economic gains, such as in crop breeding, wood utilization and animal nutrition. He also gives the anatomical basis of commercially valuable compounds that occur in herb, spice and drug plants. The final chapters are used to illustrate the integration of plant anatomy with a range of diverse areas such as forensic science, archaeology, anthropology, climatology and the arts. The text is easy to read because of the minimal use of technical terminology and there is also a short but valuable glossary to help where this is unavoidable. References for further reading at the end of each chapter have been restricted to key recent works and to citations to classical textbooks and reviews, and information is provided on a number of useful websites dealing with plant anatomy. This book does not cover the subject of plant anatomy exhaustively, concentrating on seed plants, particularly angiosperms, and the emphasis of the work described naturally reflects the author's research interests in the anatomy of wood. Unlike most books on plant anatomy, however, this one succeeds in integrating structural biology with other areas of plant science and gives many amply illustrated examples of ubiquitous structures as well as of common but often neglected specialized anatomical features. This emphasizes the basic heterogeneity of plant organs at the cellular level and reinforces the view that a realistic interpretation of plant function can only be achieved through a comprehensive knowledge of the structure and organization of cells and tissues. To paraphrase Katherine Esau, the study of the development of form and organization requires the constant correlation between molecular, biochemical and structural changes in the experimental plant (Esau, 1960). There is therefore much to recommend this book, and it should be of interest both to plant biology students requiring some awareness of plant anatomy and to current molecular-based biologists attempting to determine how modifications in gene activity translate into the higher order phenotypic characteristics of plants.

Epithelial-mesenchymal interactions play important roles in morphogenesis, histogenesis, and keratinization of the vertebrate integument. In the anterior metatarsal region of the chicken, morphogenesis results in the formation of distinct overlapping scutate scales. Recent studies have shown that the dermis of scutate scales is involved in the expression of the beta keratin gene products, which characterize terminal differentiation of the epidermis on the outer scale surface (Sawyer et al.: Dev. Biol. 101:8-18, '84; Shames and Sawyer: Dev. Biol. 116:15-22, '86; Shames and Sawyer: In A.A. Moscona and A. Monroy (eds), R.H. Sawyer (Vol. ed): Current Topics in Developmental Biology. Vol. 22: The Molecular and Developmental Biology of Keratins. New York: Academic Press, pp. 235-253, '87). Since alpha and beta keratins are both found in the scutate scale and are members of two different multigene families, it is important to know the precise location of these distinct keratins within the epidermis. In the present study, we have used protein A-gold immunoelectron microscopy with antisera made against avian alpha and beta keratins to specifically localize these keratins during development of the scutate scale to better understand the relationship between dermal cues and terminal differentiation. We find that the bundles of 3-nm filaments, characteristic of tissues known to produce beta keratins, react specifically with antiserum which recognizes beta keratin polypeptides and are found in the embryonic subperiderm that covers the entire scutate scale and in the stratum intermedium and stratum corneum making up the platelike beta stratum of the outer scale surface. Secondly, we find that 8-10-nm tonofilaments react specifically with antiserum that recognizes alpha keratin polypeptides and are located in the germinative basal cells and the lowermost cells of the stratum intermedium of the outer scale surface, as well as in the embryonic alpha stratum, which is lost from the outer surface of the scale at hatching. The alpha keratins are found throughout the epidermis of the inner surface of the scale and the hinge region. Thus, the present study further supports the hypothesis that the tissue interactions responsible for the formation of the beta stratum of scutate scales do not directly activate the synthesis of beta keratins in the germinative cells but influence these cells so that they or their progeny will activate specific beta keratin genes at the appropriate time and place.

The Biology of Cancer is a textbook for undergraduate and graduate biology students as well as medical students studying the molecular and cellular bases of cancer. The book presents the principles of cancer biology in an organized, cogent, and in-depth manner. The clarity of writing and the lucid full-color art program make the book accessible and engaging. The information unfolds through the presentation of key experiments which give readers a sense of discovery and provides insights into the conceptual foundation underlying modern cancer biology. The Biology of Cancer synthesizes the findings of three decades of recent cancer research and proposes a conceptual framework from which to teach about these discoveries. It provides the necessary structure, organization, and content for a course on cancer biology for advanced undergraduates and beginning doctoral students. The book is comprehensive and offers many pedagogical features to assist teaching and learning. The book includes many recent and topical references, and is intended to empower the student to move directly into the primary research literature. The text is up-to-date and provides current information on topics such as tumor stem cells and recently introduced chemotherapeutics. State-of-the-art techniques are discussed throughout. Modern biomedical research is explored, helping readers to hone their analytical abilities and to assimilate and think clearly about complex biological processes. The Biology of Cancer provides insights into many aspects of immunology, developmental biology, and neurobiology. The exceptional full-color art program contains many images published for the first time. The book is extensively illustrated with schematic drawings, micrographs, computer-generated models and graphs. The pieces were chosen to support and clarify the concepts, as well as to supply additional interest. Besides its value as a textbook, The Biology of Cancer will be a useful reference for individuals working in biomedical laboratories, and for clinical professionals.

BACKGROUND: Functional-structural plant models (FSPMs) explore and integrate relationships between a plant's structure and processes that underlie its growth and development. In the last 20 years, scientists interested in functional-structural plant modelling have expanded greatly the range of topics covered and now handle dynamical models of growth and development occurring from the microscopic scale, and involving cell division in plant meristems, to the macroscopic scales of whole plants and plant communities. SCOPE: The FSPM approach occupies a central position in plant science; it is at the crossroads of fundamental questions in systems biology and predictive ecology. This special issue of Annals of Botany features selected papers on critical areas covered by FSPMs and examples of comprehensive models that are used to solve theoretical and applied questions, ranging from developmental biology to plant phenotyping and management of plants for agronomic purposes. Altogether, they offer an opportunity to assess the progress, gaps and bottlenecks along the research path originally foreseen for FSPMs two decades ago. This review also allows discussion of current challenges of FSPMs regarding (1) integration of multidisciplinary knowledge, (2) methods for handling complex models, (3) standards to achieve interoperability and greater genericity and (4) understanding of plant functioning across scales. CONCLUSIONS: This approach has demonstrated considerable progress, but has yet to reach its full potential in terms of integration and heuristic knowledge production. The research agenda of functional-structural plant modellers in the coming years should place a greater emphasis on explaining robust emergent patterns, and on the causes of possible deviation from it. Modelling such patterns could indeed fuel both generic integration across scales and transdisciplinary transfer. In particular, it could be beneficial to emergent fields of research such as model-assisted phenotyping and predictive ecology in managed ecosystems.

Annual Review of Cell and Developmental Biology 2001 Editor: Randy Schekman Bibliographic Data: Annual Reviews, 2001. ISBN: 0-8243-3117-6, Series Title: Annual Reviews, v. 17, 858 pp, hard cover, $203.50. Reviewer's Expert Opinion: Description: This volume of the Annual Review of Cell and Developmental Biology contains 23 reviews of current, important topics in the broad area of cell and developmental biology in animal and plant systems. Purpose: The Annual Reviews publish comprehensive, up-to-date reviews of many topics of interest to the broad biological community. The reviews are anticipated and welcomed by the biological community. This volume maintains the high standards expected of this series. Audience: These reviews are suitable sources of information for any scientist from advanced undergraduates to senior research scientists. The writing and editing is such that a novice or expert in the field would find a review comprehensive and informative. Each of the reviews is written by one to four authors. They are the acknowledged experts in their respective fields. Features: The reviews in this volume cover a broad range of topics. Each review is thoroughly referenced with the most relevant and current references. Many of the reviews cover aspects of cell or developmental biology that represent the merging of more traditional, separate disciplines and all address topics of considerable current interest. Many of the chapters have color plates that are reproduced very well on high quality paper. Assessment: This is another excellent collection of reviews in this series. It is one of the best among many volumes of reviews published annually. No university library should be without it. Many individuals find it worthwhile to own a personal copy.

Although insect endocrinology is one of the oldest and most active branches of insect physiology, its classic general texts are long out of date, while its abundant primary literature provides little biological context in which to make sense of the discipline as a whole. In this book, H. Frederik Nijhout's goal is to provide a complete, concise, and up-to-date source for students and nonspecialists seeking an overview of the dynamic and wide-ranging science that insect endocrinology has become since its beginnings nearly eighty years ago in the study of insect metamorphosis. The author offers a comprehensive survey of the many roles that hormones play in the biology of insects. Among the topics discussed are the control of molting, metamorphosis, reproduction, caste determination in social insects, diapause, migration, carbohydrate and lipid metabolism, diuresis, and behavior. The account features a summary of the most current and accurate thinking on the complex roles of ecdysone and juvenile hormone in the control of metamorphosis, a process still misunderstood and misrepresented in biological textbooks and many professional reviews. Throughout, the book's emphasis is on the biology of the organism and the ways in which physiological and developmental regulatory mechanisms are integrated into the insect's life cycle.

Leading scholars report on current research that demonstrates the central role of cultural evolution in explaining human behavior. Over the past few decades, a growing body of research has emerged from a variety of disciplines to highlight the importance of cultural evolution in understanding human behavior. Wider application of these insights, however, has been hampered by traditional disciplinary boundaries. To remedy this, in this volume leading researchers from theoretical biology, developmental and cognitive psychology, linguistics, anthropology, sociology, religious studies, history, and economics come together to explore the central role of cultural evolution in different aspects of human endeavor. The contributors take as their guiding principle the idea that cultural evolution can provide an important integrating function across the various disciplines of the human sciences, as organic evolution does for biology. The benefits of adopting a cultural evolutionary perspective are demonstrated by contributions on social systems, technology, language, and religion. Topics covered include enforcement of norms in human groups, the neuroscience of technology, language diversity, and prosociality and religion. The contributors evaluate current research on cultural evolution and consider its broader theoretical and practical implications, synthesizing past and ongoing work and sketching a roadmap for future cross-disciplinary efforts. Contributors Quentin D. Atkinson, Andrea Baronchelli, Robert Boyd, Briggs Buchanan, Joseph Bulbulia, Morten H. Christiansen, Emma Cohen, William Croft, Michael Cysouw, Dan Dediu, Nicholas Evans, Emma Flynn, Pieter François, Simon Garrod, Armin W. Geertz, Herbert Gintis, Russell D. Gray, Simon J. Greenhill, Daniel B. M. Haun, Joseph Henrich, Daniel J. Hruschka, Marco A. Janssen, Fiona M. Jordan, Anne Kandler, James A. Kitts, Kevin N. Laland, Laurent Lehmann, Stephen C. Levinson, Elena Lieven, Sarah Mathew, Robert N. McCauley, Alex Mesoudi, Ara Norenzayan, Harriet Over, Jürgen Renn, Victoria Reyes-García, Peter J. Richerson, Stephen Shennan, Edward G. Slingerland, Dietrich Stout, Claudio Tennie, Peter Turchin, Carel van Schaik, Matthijs Van Veelen, Harvey Whitehouse, Thomas Widlok, Polly Wiessner, David Sloan Wilson

Timing of flowering is not only an interesting topic in developmental biology, but it also plays a significant role in agriculture for its effects on the maturation time of seed. The hexaploid wheat (Triticum aestivum) is one of the most important crop species whose flowering time, i.e. heading time, greatly influences yield. However, it remains unclear whether and how microRNAs regulate heading time in it. In our current study, we identified the tae-miR408 in wheat and its targets in vivo, including Triticum aestivum TIMING OF CAB EXPRESSION-A1 (TaTOC-A1), TaTOC-B1, and TaTOC-D1. The tae-miR408 levels were reciprocal to those of TaTOC1s under long-day and short-day conditions. Wheat plants with a knockdown of TaTOC1s via RNA interference and overexpression of tae-miR408 showed early-heading phenotype. Furthermore, TaTOC1s expression was down-regulated by the tae-miR408 in the hexaploid wheat. In addition, other important agronomic traits in wheat, such as plant height and flag leaf angle, were regulated by both tae-miR408 and TaTOC1s. Thus, our results suggested that the tae-miR408 functions in the wheat heading time by mediating TaTOC1s expression, and the study provides important new information on the mechanism underlying heading time regulation in wheat.

Neo-Darwinism currently occupies a dominant position in evolutionary thought. While this theory has considerable explanatory power, it is widely recognized as being incomplete in that it lacks a component dealing with individual development, or ontogeny. This is particularly conspicuous in relation to attempts to explain the evolutionary origin of the 35 or so animal body plans, and of the developmental trajectories that generate them. This book examines both the origin of body plans in particular and the evolution of animal development in general. In doing so, it ranges widely, covering topics as diverse as comparative developmental genetics, selection theory and Vendian/Cambrian fossils. Particular emphasis is placed on gene duplication, changes in spatio-temporal gene-expression patterns, internal selection, coevolution of interacting genes, and coadaptation. The book will be of particular interest to students and researchers in evolutionary biology, genetics, paleontology and developmental biology.

This book brings together for the first time philosophers of biology to write about some of the most central concepts and issues in their field from the perspective of biology education. The chapters of the book cover a variety of topics ranging from traditional ones, such as biological explanation, biology and religion or biology and ethics, to contemporary ones, such as genomics, systems biology or evolutionary developmental biology. Each of the 30 chapters covers the respective philosophical literature in detail and makes specific suggestions for biology education. The aim of this book is to inform biology educators, undergraduate and graduate students in biology and related fields, students in teacher training programs, and curriculum developers about the current state of discussion on the major topics in the philosophy of biology and its implications for teaching biology. In addition, the book can be valuable to philosophers of biology as an introductory text in undergraduate and graduate courses.

PURPOSE OF REVIEW: A wealth of new experimental evidence has been published over the past year that has helped refine our models of blood cell development. We will review this information, discuss the current models of hematopoietic ontogeny and provide perspective on current and future research directions, with an emphasis on how studies in the zebrafish are helping us better understand how hematopoietic stem cells are formed in the vertebrate embryo. RECENT FINDINGS: Several important studies have been published recently addressing the embryonic development of hematopoietic stem cells. These studies have helped clarify several controversial topics in developmental hematopoiesis, including the concepts of the hemangioblast and hemogenic endothelium. In particular, the postulate that hematopoietic stem cells arise through hemogenic endothelial intermediates has been greatly strengthened by a collection of convincing publications reviewed below. SUMMARY: A precise understanding of how hematopoietic stem cells are patterned during development has important implications for both developmental biology and regenerative medicine. Since hematopoietic stem cells are the only hematopoietic cells capable of lifelong, multilineage blood cell production, understanding the stepwise, molecular processes of their instruction from mesoderm is key to replicating these events in vitro from pluripotent embryonic stem cells.

Over the past few decades, a growing body of research has emerged from a variety of disciplines to highlight the importance of cultural evolution in understanding human behavior. Wider application of these insights, however, has been hampered by traditional disciplinary boundaries. To remedy this, in this volume leading researchers from theoretical biology, developmental and cognitive psychology, linguistics, anthropology, sociology, religious studies, history, and economics come together to explore the central role of cultural evolution in different aspects of human endeavor. The contributors take as their guiding principle the idea that cultural evolution can provide an important integrating function across the various disciplines of the human sciences, as organic evolution does for biology. The benefits of adopting a cultural evolutionary perspective are demonstrated by contributions on social systems, technology, language, and religion. Topics covered include enforcement of norms in human groups, the neuroscience of technology, language diversity, and prosociality and religion. The contributors evaluate current research on cultural evolution and consider its broader theoretical and practical implications, synthesizing past and ongoing work and sketching a roadmap for future cross-disciplinary efforts. ContributorsQuentin D. Atkinson, Andrea Baronchelli, Robert Boyd, Briggs Buchanan, Joseph Bulbulia, Morten H. Christiansen, Emma Cohen, William Croft, Michael Cysouw, Dan Dediu, Nicholas Evans, Emma Flynn, Pieter Francois, Simon Garrod, Armin W. Geertz, Herbert Gintis, Russell D. Gray, Simon J. Greenhill, Daniel B. M. Haun, Joseph Henrich, Daniel J. Hruschka, Marco A. Janssen, Fiona M. Jordan, Anne Kandler, James A. Kitts, Kevin N. Laland, Laurent Lehmann, Stephen C. Levinson, Elena Lieven, Sarah Mathew, Robert N. McCauley, Alex Mesoudi, Ara Norenzayan, Harriet Over, Jurgen Renn, Victoria Reyes-Garcia, Peter J. Richerson, Stephen Shennan, Edward G. Slingerland, Dietrich Stout, Claudio Tennie, Peter Turchin, Carel van Schaik, Matthijs Van Veelen, Harvey Whitehouse, Thomas Widlok, Polly Wiessner, David Sloan Wilson.

This chapter provides a general introduction to phenotypic plasticity by presenting key concepts, using simple examples and comprehensive, up-to-date references. A background section covers the norm of reaction; adaptive and maladaptive plasticity; canalization versus plasticity; and eco-devo (ecological developmental biology). The chapter briefly explains the biology that underlies statistical genotype-by-environment interaction along with analytical, interpretive, and selective implications, including the question of evolutionary potential in novel environments. A discussion of environmental cues and their possible transduction pathways provides background for understanding diverse systems of plasticity and offers guidance for designing plasticity experiments and choosing focal aspects of response. In a section addressing inherited effects of parental environment on offspring phenotypes, the chapter introduces the more controversial topic of transgenerational plasticity and points to questions regarding its potential adaptive impact and epigenetic transmission dynamics. The chapter closes by proposing that both previous and current conditions contribute to individual plasticity in an integrated way, and framing a set of productive avenues for future research.