Aims of undergraduate physiology education: a view from the University of Chicago

Physiology may play an important, if not essential role, in a liberal arts education because it provides a context for integrating information and concepts from diverse biological and extra-biological disciplines. Instructors of physiology may aid in fulfilling this role by clarifying the core concepts that physiological details exemplify. As an example, presented here are the core principles that are the basis for an undergraduate physiology course taught at the University of Chicago. The first of these is: Evolution has resulted in organisms comprising mechanisms for maintenance, growth, and reproduction, despite perturbations of the internal and external environment. Such principles necessitate a coupling of physiology to diverse disciplines (i.e., "sciomics") and provide a basis for integrating discoveries in other disciplines.     

The nature of systems biology

The advent of functional genomics has enabled the molecular biosciences to come a long way towards characterizing the molecular constituents of life. Yet, the challenge for biology overall is to understand how organisms function. By discovering how function arises in dynamic interactions, systems biology addresses the missing links between molecules and physiology. Top-down systems biology identifies molecular interaction networks on the basis of correlated molecular behavior observed in genome-wide "omics" studies. Bottom-up systems biology examines the mechanisms through which functional properties arise in the interactions of known components. Here, we outline the challenges faced by systems biology and discuss limitations of the top-down and bottom-up approaches, which, despite these limitations, have already led to the discovery of mechanisms and principles that underlie cell function.     

Learning developmental biology has priority in the life sciences curriculum in Singapore

Singapore has embraced the life sciences as an important discipline to be emphasized in schools and universities. This is part of the nation's strategic move towards a knowledge-based economy, with the life sciences poised as a new engine for economic growth. In the life sciences, the area of developmental biology is of prime interest, since it is not just intriguing for students to know how a single cell can give rise to a complex, coordinated, functional life that is multicellular and multifaceted, but more importantly, there is much in developmental biology that can have biomedical implications. At different levels in the Singapore educational system, students are exposed to various aspects of developmental biology. The author has given many guest lectures to secondary (ages 12-16) and high school (ages 17-18) students to enthuse them about topics such as embryo cloning and stem cell biology. At the university level, some selected topics in developmental biology are part of a broader course which caters for students not majoring in the life sciences, so that they will learn to comprehend how development takes place and the significance of the knowledge and impacts of the technologies derived in the field. For students majoring in the life sciences, the subject is taught progressively in years two and three, so that students will gain specialist knowledge in developmental biology. As they learn, students are exposed to concepts, principles and mechanisms that underlie development. Different model organisms are studied to demonstrate the rapid advances in this field and to show the interconnectivity of developmental themes among living things. The course inevitably touches on life and death matters, and the social and ethical implications of recent technologies which enable scientists to manipulate life are discussed accordingly, either in class, in a discussion forum, or through essay writing.     

The cost of circadian desynchrony: Evidence,insights and open questions

Coordinated daily rhythms are evident in most aspects of our physiology, driven by internal timing systems known as circadian clocks. Our understanding of how biological clocks are built and function has grown exponentially over the past 20 years. With this has come an appreciation that disruption of the clock contributes to the pathophysiology of numerous diseases, from metabolic disease to neurological disorders to cancer. However, it remains to be determined whether it is the disruption of our rhythmic physiology per se (loss of timing itself), or altered functioning of individual clock components that drive pathology. Here, we review the importance of circadian rhythms in terms of how we (and other organisms) relate to the external environment, but also in relation to how internal physiological processes are coordinated and synchronized. These issues are of increasing importance as many aspects of modern life put us in conflict with our internal clockwork.

     

Comparative endocrinology in the 21st century

Hormones coordinate developmental, physiological, and behavioral processes within and between all living organisms. They orchestrate and shape organogenesis from early in development, regulate the acquisition, assimilation, and utilization of nutrients to support growth and metabolism, control gamete production and sexual behavior, mediate organismal responses to environmental change, and allow for communication of information between organisms. Genes that code for hormones; the enzymes that synthesize, metabolize, and transport hormones; and hormone receptors are important targets for natural selection, and variation in their expression and function is a major driving force for the evolution of morphology and life history. Hormones coordinate physiology and behavior of populations of organisms, and thus play key roles in determining the structure of populations, communities, and ecosystems. The field of endocrinology is concerned with the study of hormones and their actions. This field is rooted in the comparative study of hormones in diverse species, which has provided the foundation for the modern fields of evolutionary, environmental, and biomedical endocrinology. Comparative endocrinologists work at the cutting edge of the life sciences. They identify new hormones, hormone receptors and mechanisms of hormone action applicable to diverse species, including humans; study the impact of habitat destruction, pollution, and climatic change on populations of organisms; establish novel model systems for studying hormones and their functions; and develop new genetic strains and husbandry practices for efficient production of animal protein. While the model system approach has dominated biomedical research in recent years, and has provided extraordinary insight into many basic cellular and molecular processes, this approach is limited to investigating a small minority of organisms. Animals exhibit tremendous diversity in form and function, life-history strategies, and responses to the environment. A major challenge for life scientists in the 21st century is to understand how a changing environment impacts all life on earth. A full understanding of the capabilities of organisms to respond to environmental variation, and the resilience of organisms challenged by environmental changes and extremes, is necessary for understanding the impact of pollution and climatic change on the viability of populations. Comparative endocrinologists have a key role to play in these efforts.     

Functional genomics the old-fashioned way: chemical mutagenesis in mice

Genetic studies using mutants have led to a greater understanding of the mechanisms underlying the physiology, biochemistry and development of organisms. The increasing availability of complete genome sequences has stimulated genome-wide mutagenesis approaches in model organisms. In an ideal model system, it would be possible to choose from a series of mutations in any given gene to study its function, regulation and interaction with other genes; flies and worms with their rich mutant resources provide such models. Because the mouse is a powerful vertebrate model for human disease, it would be advantageous to have an equally comprehensive mutant collection. Recently, much to the joy of the mouse community, two papers, describe screens to generate such a collection. In an ongoing screen, the groups of Brown and Balling have generated over 40,000 F1 mutant mice by treating males with the super mutagen N-ethyl-N-nitrosourea. 300-500 mice are being screened each week using various objective tests and paradigms for morphological, developmental, clinical and behavioral abnormalities. In combination, these analyses have produced an unbiased set of about 700 new dominant, semidominant and recessive mutations.     

Social structure and indirect genetic effects: genetics of social behaviour

The social environment modulates gene expression, physiology, behaviour and patterns of inheritance. For more than 50 years, this concept has been investigated using approaches that include partitioning the social component out of behavioural heritability estimates, studying maternal effects on offspring, and analysing dominance hierarchies. Recent advances have formalized this ‘social environment effect’ by providing a more nuanced approach to the study of social influences on behaviour while recognizing evolutionary implications. Yet, in most of these formulations, the dynamics of social interactions are not accounted for. Also, the reciprocity between individual behaviour and group‐level interactions has been largely ignored. Consistent with evolutionary theory, the principles of social interaction are conserved across a broad range of taxa. While noting parallels in diverse organisms, this review uses Drosophila melanogaster as a case study to revisit what is known about social interaction paradigms. We highlight the benefits of integrating the history and pattern of interactions among individuals for dissecting molecular mechanisms that underlie social modulation of behaviour.     

Investigation of pituitary adenylate cyclase activating polypeptide (PACAP) in human amniotic fluid samples

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide acting as a hormone, a neuromodulator, a neurotransmitter, a trophic factor and is involved in a variety of developmental and regenerative processes. PACAP is present in several human tissues and biological fluids. In many pathological conditions, changes in PACAP levels have been described to reflect disease progression, therefore PACAP has diagnostic value as a potential biomarker. Since PACAP has been shown to play an important role in reproductive physiology and development, it was of interest to examine whether this neuropeptide occurs in the human amniotic fluid. Amniotic fluid samples were collected between the 15-19^th weeks of gestation from volunteering pregnant women undergoing amniocentesis as a prenatal diagnostic tool due to maternal age. Pathological cases were excluded after prenatal karyotype analysis. PACAP-like immunoreactivity was measured by radioimmunoassay and could be detected in all samples. The present study provides evidence for the presence of PACAP in human amniotic fluid, but determination of the exact physiological or pathological significance awaits further investigation.     

Glycosylation in cellular mechanisms of health and disease

Glycosylation produces an abundant, diverse, and highly regulated repertoire of cellular glycans that are frequently attached to proteins and lipids. The past decade of research on glycan function has revealed that the enzymes responsible for glycosylation-the glycosyltransferases and glycosidases-are essential in the development and physiology of living organisms. Glycans participate in many key biological processes including cell adhesion, molecular trafficking and clearance, receptor activation, signal transduction, and endocytosis. This review discusses the increasingly sophisticated molecular mechanisms being discovered by which mammalian glycosylation governs physiology and contributes to disease.     

Reduce, reuse, and recycle: developmental evolution of trait diversification

A major focus of evolutionary developmental (evo-devo) studies is to determine the genetic basis of variation in organismal form and function, both of which are fundamental to biological diversification. Pioneering work on metazoan and flowering plant systems has revealed conserved sets of genes that underlie the bauplan of organisms derived from a common ancestor. However, the extent to which variation in the developmental genetic toolkit mirrors variation at the phenotypic level is an active area of research. Here we explore evidence from the angiosperm evo-devo literature supporting the frugal use of genes and genetic pathways in the evolution of developmental patterning. In particular, these examples highlight the importance of genetic pleiotropy in different developmental modules, thus reducing the number of genes required in growth and development, and the reuse of particular genes in the parallel evolution of ecologically important traits.     

微弱发光分析技术应用实例(五)

多数生物系统存在低水平化学发光,这种化学发光与生物体内的生理反应有关.生活在水和空气中的生物体受到各种污染因素危害必定引起生理变化,从而引起这种低水平化学发光的改变.利用这种现象,将某些生物体作为生物探测器,应用微弱发光分析技术可以检测水体和大气的污染程度.     

Selective processes in development: implications for the costs and benefits of phenotypic plasticity

Adaptive phenotypic plasticity, the ability of a genotype to develop a phenotype appropriate to the local environment, allows organisms to cope with environmental variation and has implications for predicting how organisms will respond to rapid, human-induced environmental change. This review focuses on the importance of developmental selection, broadly defined as a developmental process that involves the sampling of a range of phenotypes and feedback from the environment reinforcing high-performing phenotypes. I hypothesize that understanding the degree to which developmental selection underlies plasticity is key to predicting the costs, benefits, and consequences of plasticity. First, I review examples that illustrate that elements of developmental selection are common across the development of many different traits, from physiology and immunity to circulation and behavior. Second, I argue that developmental selection, relative to a fixed strategy or determinate (switch) mechanisms of plasticity, increases the probability that an individual will develop a phenotype best matched to the local environment. However, the exploration and environmental feedback associated with developmental selection is costly in terms of time, energy, and predation risk, resulting in major changes in life history such as increased duration of development and greater investment in individual offspring. Third, I discuss implications of developmental selection as a mechanism of plasticity, from predicting adaptive responses to novel environments to understanding conditions under which genetic assimilation may fuel diversification. Finally, I outline exciting areas of future research, in particular exploring costs of selective processes in the development of traits outside of behavior and modeling developmental selection and evolution in novel environments.     

A special issue on ＂Plant Molecular Biology＂

The use of molecular biology and genomics tools in plant biology research has greatly expanded our understandingof the molecular mechanisms that underlie plant development and physiology.The successful establishment of researchresources such as mutant populations has led to progress in a variety of fields,including plant reproductive develop-ment,signal transduction,hormone functions,defense responses and epigenetic control.In the future these advanceswill potentially facilitate crop improvement through molecular breeding.     

Methodological Aspects of Studies of the Physiology of Child Development

Theoretical prerequisites to the studies of the physiology of child development are considered. The problems of developmental periods and the criteria for their determination are discussed in terms of the concept of the adaptive character of development and the mechanisms of systemic organization of adaptive reactions. The authors suggest that in the determination of developmental periods it is necessary to take into account both the features of the morphofunctional maturity of the organism and the mechanisms, which allow its interaction with the environment. The question of the sensitive and critical developmental periods is discussed in these terms, as well as the biological and social factors, which determine these periods.     

International Society of Chronobiology: Membership Information

The International Society for Chronobiology has as its aims, furthering the study of temporal changes in living matter, including biological rhythms in development and ageing in individuals and populations; studying and defining the mechanisms of temporal changes; fostering practical applications for chronobiological findings to mankind in basic and applied biology, physiology, work hygiene and the medical sciences; promoting education in and wide understanding of chronobiology; and furthering contact between scientists in the field and providing a forum for practitioners of chronobiology.     

International Society of Chronobiology: Membership Information

The International Society for Chronobiology has as its aims, furthering the study of temporal changes in living matter, including biological rhythms in development and ageing in individuals and populations; studying and defining the mechanisms of temporal changes; fostering practical applications for chronobiological findings to mankind in basic and applied biology, physiology, work hygiene and the medical sciences; promoting education in and wide understanding of chronobiology; and furthering contact between scientists in the field and providing a forum for practitioners of chronobiology.     

Zur Biologie der Relationen

Size matters The size of organisms has multiple consequences, which must not be ignored in all biological inferences of any function, it may concern the organism itself (functional morphology, physiology, reproductive biology), of its environment (autecology) or but to understand the big game we call evolution.     

Evidence of a hemolymph-born factor that induces onset of maturation in Manduca sexta larvae

Insect metamorphosis is a complex developmental transition determined and coordinated by hormonal signaling that begins at a critical weight late in the larval phase of life. Even though this hormonal signaling is well understood in insects, the internal factors that are assessed at the critical weight and that drive commitment to metamorphosis have remained unresolved in most species. The critical weight may represent either an autonomous decision by the neuroendocrine system without input from other developing larval tissues, or an assessment of developmental thresholds occurring throughout the body that are then integrated by the neuroendocrine tissues. The latter hypothesis predicts that there could be one or more developmental threshold signals that originate from developing tissues and ultimately induce the onset of metamorphosis. However, there is no evidence for such a signal in the organisms for which the critical weight is well described. Here we test for the evidence of this factor in Manduca sexta (Lepidoptera: Sphingidae) by transferring hemolymph from individuals that are either post- or pre-critical weight into pre-critical weight 5^th instar larvae. We found that hemolymph from a post-critical weight donor induces a shortening of development time, though the mass at pupation is unaffected. This suggests that metamorphic commitment occurring at the critical weight is at least partially coordinated by signaling from developing tissues via a hemolymph-borne signaling factor.     

An essay on the evolution of cognition: Constructing a theoretical conceptual framework

In this essay we provide an interdisciplinary approach to the problem of the evolution of human cognition and suggest the theoretical framework of genetic system theory (GST) for organizing the relevant content of several disciplines. This bio-social-cultural theory is based on the assumption that organisms are dynamic systems which interact with one another and their environment and are themselves composed of dynamic internal relations at several levels. Special emphasis will be placed upon these internal cellular and molecular mechanisms underlying the physiological mechanisms of learning and memory. The human individual organism is emphasized because in its experiential activity over time it is the site of integration for social, and cultural stimuli and because of its unique properties among living things. The primary disciplines for our discussion are drawn from the biological, social, and humanistic sciences and several concrete examples are given from each science.     

Structure and function of the homeotic gene complex (HOM-C) in the beetle, Tribolium castaneum

The powerful combination of genetic, developmental and molecular approaches possible with the fruit fly, Drosophila melanogaster, has led to a profound understanding of the genetic control of early developmental events. However, Drosophila is a highly specialized long germ insect, and the mechanisms controlling its early development may not be typical of insects or Arthropods in general. The beetle, Tribolium castaneum, offers a similar opportunity to integrate high resolution genetic analysis with the developmental/molecular approaches currently used in other organisms. Early results document significant differences between insect orders in the functions of genes responsible for establishing developmental commitments.