Four decades of teaching developmental biology in Germany

I have taught developmental biology in Essen for 30 years. Since my department is named Zoophysiologie (Zoophysiology), besides Developmental Biology, I also have to teach General Animal Physiology. This explains why the time for teaching developmental biology is restricted to a lecture course, a laboratory course and several seminar courses. However, I also try to demonstrate in the lecture courses on General Physiology the close relationship between developmental biology, physiology, morphology, anatomy, teratology, carcinogenesis, evolution and ecology (importance of environmental factors on embryogenesis). Students are informed that developmental biology is a core discipline of biology. In the last decade, knowledge about molecular mechanisms in different organisms has exponentially increased. The students are trained to understand the close relationship between conserved gene structure, gene function and signaling pathways, in addition to or as an extension of, classical concepts. Public reports about the human genome project and stem cell research (especially therapeutic and reproductive cloning) have shown that developmental biology, both in traditional view and at the molecular level, is essential for the understanding of these complex topics and for serious and non-emotional debate.     

The acquisition of conscience and Developmental Systems Theory

Summary Proponents of Developmental Systems Theory (DST) argue that it offers an alternative to current research programs in biology that are built on the historic disjunction between evolutionary and developmental biology. In this paper I illustrate how DST can be used to account for the acquisition of an important component of moral agency, conscience. Susan Oyama, a major proponent of DST, has set moral issues outside the compass of DST. Thus, I examine her reasons for restricting DST to non-moral matters, and argue that they are not decisive. On the positive side, I argue that DST not only is compatible with attempts to describe and explain moral agency but also aids us in understanding it. In particular, I show how DST can provide a fruitful perspective for viewing some significant current findings and theories in moral developmental psychology about the acquisition of conscience. The familiar dichotomies resisted by DST, those between genes and environment, inherited and acquired, innate and learned, and biological and cultural, have also plagued human developmental psychology, including moral development. By bringing a DST perspective to the study of moral development, I illustrate how a DST perspective might offer a promising way to reconceive that phenomenon, and provide some insights into how further work in understanding the development of moral agency might proceed. Thus, I hope to contribute to the current efforts of proponents of DST to integrate developmental and evolutionary considerations.     

Small RNAs in development - insights from plants

microRNAs (miRNAs) and small interfering RNAs (siRNAs), which constitute two major classes of endogenous small RNAs in plants, impact a multitude of developmental and physiological processes by imparting sequence specificity to gene and genome regulation. Although lacking the third major class of small RNAs found in animals, Piwi-interacting RNAs (piRNAs), plants have expanded their repertoire of endogenous siRNAs, some of which fulfill similar molecular and developmental functions as piRNAs in animals. Research on plant miRNAs and siRNAs has contributed invaluable insights into small RNA biology, thanks to the highly conserved molecular logic behind the biogenesis and actions of small RNAs. Here, I review progress in the plant small RNA field in the past two years, with an emphasis on recent findings related to plant development. I do not recount the numerous developmental processes regulated by small RNAs; instead, I focus on major principles that have been derived from recent studies and draw parallels, when applicable, between plants and animals.     

Virtual labs: a substitute for traditional labs?

Current technologies give us the ability to enhance and replace developmental biology classes with computer-based resources, often called virtual labs. In the process of using these resources, teachers may be tempted to neglect the simpler technologies and lab bench activities, which can be labor intensive. In this paper, I take a critical look at the role of computer-based materials for the teaching of developmental biology in order to aid teachers in assessing their value. I conclude that while digital tools have value, they should not replace all of the traditional laboratory activities. Clearly, both computer-enhanced activities and traditional labs must be included in laboratory exercises. Reliance on only one or the other is inappropriate. In order to determine when it is appropriate to use a particular educational tool, the goals of the course and the needs of biology students for an education that gives them a realistic and engaged view of biology must be understood. In this paper, I dispel some of the myths of computer tools and give specific guidelines for assessing their usage, taking into account the special needs of a developmental biology class and the difficulties of observing all the developmental stages of subject organisms in the timescale of class meetings.     

Examining developmental plasticity in the skeletal system through a sensitive developmental windows framework

Developmental plasticity facilitates energetically costly but potentially fitness-enhancing adjustments to phenotypic trajectories in response to environmental stressors, and thus may significantly impact patterns of growth, morbidity, and mortality over the life course. Ongoing research into epigenetics and developmental biology indicate that the timing of stress exposures is a key factor when assessing their impact on developmental processes. Specifically, stress experienced within sensitive developmental windows (SDWs), discrete developmental periods characterized by heightened energy requirements and rapid growth, may alter the pace and tempo of growth in ways that significantly influence phenotypic development over both the short and long term. In human skeletal biology, efforts to assess how developmental environments shape health outcomes over the life course could be enhanced by incorporating the SDW concept into existing methodological approaches. The goal of this article is to outline an interpretive framework for identifying and interpreting evidence of developmental stress in the skeletal system using the SDW concept. This framework provides guidance for the identification of elements most likely to capture evidence of stress most relevant to a study's core research questions, the interpretation of developmental stress exhibited by those elements, and the relationship of skeletal indicators of stress to the demographic patterning of morbidity and mortality. Use of the SDW concept in skeletal biology has the potential to enrich traditional approaches to addressing developmental origins of health and disease hypotheses, by targeting periods in which individuals are most susceptible to stress and thus most likely to exhibit plasticity in response.     

Xenopus leads the way: Frogs as a pioneering model to understand the human brain

From its long history in the field of embryology to its recent advances in genetics, Xenopus has been an indispensable model for understanding the human brain. Foundational studies that gave us our first insights into major embryonic patterning events serve as a crucial backdrop for newer avenues of investigation into organogenesis and organ function. The vast array of tools available in Xenopus laevis and Xenopus tropicalis allows interrogation of developmental phenomena at all levels, from the molecular to the behavioral, and the application of CRISPR technology has enabled the investigation of human disorder risk genes in a higher‐throughput manner. As the only major tetrapod model in which all developmental stages are easily manipulated and observed, frogs provide the unique opportunity to study organ development from the earliest stages. All of these features make Xenopus a premier model for studying the development of the brain, a notoriously complex process that demands an understanding of all stages from fertilization to organogenesis and beyond. Importantly, core processes of brain development are conserved between Xenopus and human, underlining the advantages of this model. This review begins by summarizing discoveries made in amphibians that form the cornerstones of vertebrate neurodevelopmental biology and goes on to discuss recent advances that have catapulted our understanding of brain development in Xenopus and in relation to human development and disease. As we engage in a new era of patient‐driven gene discovery, Xenopus offers exceptional potential to uncover conserved biology underlying human brain disorders and move towards rational drug design.     

A matter of measurements: challenges and approaches in the comparative analysis of static allometries

Comparisons of static allometries are frequently used to gain insights into patterns and processes underlying morphological and developmental evolution. A study by J. L. Tomkins and coworkers, recently published in the American Naturalist, examined complex nonlinear allometries in three insect species in which males are dimorphic in the expression of secondary sexual traits. Employing a novel approach to analyzing male allometries in these organisms, the authors were able to show that developmental reprogramming of trait primordia is not necessary to explain allometric scaling in two of the species examined, contrary to several previous studies on the same species. Instead, male dimorphisms could be explained by simple exponential growth, an important result that carries with it major evolutionary and developmental implications. Using this study as an example, I highlight some of the methodological challenges involved in analyzing and comparing static allometries and in inferring the developmental processes that underlie them. I end by discussing how correct application of hypothesis testing, on one side, and basic anatomy and developmental biology, on the other, should guide how morphology is measured.     

Evolution and nature of science instruction

In this article, I provide an analysis of my work (1985–present) with non-major biology students and science teacher candidates in developing strategies for teaching and enhancing learning with respect to evolutionary science. This first-person account describes changes in evolution instruction over the course of a career based on personal experiences, research-informed practices, and a critical collaboration with colleague Mike U. Smith. I assert four insights concerning the influence and efficacy of teaching nature of science (NOS) prior to the introduction of evolution within college courses for science non-majors and science teacher candidates. These insights are: (a) teach explicit NOS principles first; (b) integrate evolution as a theme throughout a course in introductory biology (but after NOS principles have been introduced); (c) use active learning pedagogies; and (d) use non-threatening alternative assessments to enhance student learning and acceptance of evolutionary science. Together, these insights establish a pedagogy that I (and my colleagues) have found to be efficacious for supporting novice students as they engage in the study of evolutionary science.     

Intraspecific Variation in Developmental Characters: The Origin of Evolutionary Novelties

Evolutionary developmental biology is inevitably a comparativesubject. However, the taxonomic level at which comparisons canbe made varies widely, and this greatly affects the kind ofinformation that can be gained from the comparison. Broadlyspeaking, high-level comparisons (e.g., between phyla) are moreinformative about phylogenetic pattern and homology, while low-levelcomparisons (e.g., between congeneric species) are more informativeabout evolutionary mechanisms, including speciation. However,so far evolutionary developmental biology has had a relativelyminor input into the traditional territory of population genetics,namely comparisons within species—both within and betweengeographic populations. Yet this area is crucial, as all evolutionarynovelties ultimately arise from intraspecific variation. Here,I address this issue, focusing on the question of how earlyin development novelties arise. To shed light on this question,I discuss two examples of developmental polymorphism withinspecies involving two of the main body axes: anteroposteriorsegmentation in centipedes and left–right asymmetry (chirality)in gastropods.     

EST and transcriptome analysis of cephalochordate amphioxus--past, present and future

The cephalochordates, commonly known as amphioxus or lancelets, are now considered the most basal chordate group, and the studies of these organisms therefore offer important insights into various levels of evolutionary biology. In the past two decades, the investigation of amphioxus developmental biology has provided key knowledge for understanding the basic patterning mechanisms of chordates. Comparative genome studies of vertebrates and amphioxus have uncovered clear evidence supporting the hypothesis of two-round whole-genome duplication thought to have occurred early in vertebrate evolution and have shed light on the evolution of morphological novelties in the complex vertebrate body plan. Complementary to the amphioxus genome-sequencing project, a large collection of expressed sequence tags (ESTs) has been generated for amphioxus in recent years; this valuable collection represents a rich resource for gene discovery, expression profiling and molecular developmental studies in the amphioxus model. Here, we review previous EST analyses and available cDNA resources in amphioxus and discuss their value for use in evolutionary and developmental studies. We also discuss the potential advantages of applying high-throughput, next-generation sequencing (NGS) technologies to the field of amphioxus research.     

生态学在现代科学发展中的地位

生态学这个术语由Heckel所首创(1869),在当时并未为学术界所接受,Heckel本人也时以“自然经济学”,时而以“个体生态学”取而代之。尔后,其它生态学家又作过各种不同的解释,如“自然科学史”,“自然界的结构与功能的研究”等,但对生态学解释持反对意见的也不乏其人,如俄国著名的植物生理学家季米里亚捷夫直到最后才放弃自己的意     

There May be Strict Empirical Laws in Biology, after All

This paper consists of four parts. Part 1 is an introduction. Part 2 evaluates arguments for the claim that there are no strict empirical laws in biology. I argue that there are two types of arguments for this claim and they are as follows: (1) Biological properties are multiply realized and they require complex processes. For this reason, it is almost impossible to formulate strict empirical laws in biology. (2) Generalizations in biology hold contingently but laws go beyond describing contingencies, so there cannot be strict laws in biology. I argue that both types of arguments fail. Part 3 considers some examples of biological laws in recent biological research and argues that they exemplify strict laws in biology. Part 4 considers the objection that the examples in part 3 may be strict laws but they are not distinctively biological laws. I argue that given a plausible account of what distinctively biological means, such laws are distinctively biological.     

Molecular biology of embryonic development: How far have we come in the last ten years?

The successes of molecular developmental biology over the last ten years have been particularly impressive in those directions favored by its major paradigms. New technologies have both guided and been guided by the progress of the field. I review briefly some of the major insights into embryonic development that have derived from research in four specific areas: early embryogenesis of various forms; “pattern formation”; evolutionary conservation of regulatory elements; and spatial mechanisms of gene regulation. There remain many major problem areas, some of which may require new orientations to solve.     

Neural crest cells: From developmental biology to clinical interventions

Neural crest cells are multipotent cells, which are specified in embryonic ectoderm in the border of neural plate and epiderm during early development by interconnection of extrinsic stimuli and intrinsic factors. Neural crest cells are capable of differentiating into various somatic cell types, including melanocytes, craniofacial cartilage and bone, smooth muscle, and peripheral nervous cells, which supports their promise for cell therapy. In this work, we provide a comprehensive review of wide aspects of neural crest cells from their developmental biology to applicability in medical research. We provide a simplified model of neural crest cell development and highlight the key external stimuli and intrinsic regulators that determine the neural crest cell fate. Defects of neural crest cell development leading to several human disorders are also mentioned, with the emphasis of using human induced pluripotent stem cells to model neurocristopathic syndromes. Birth Defects Research (Part C) 102:263–274, 2014. © 2014 Wiley Periodicals, Inc.     

Making developmental biology relevant to undergraduates in an era of economic rationalism in Australia

This report describes the road map we followed at our university to accommodate three main factors: financial pressure within the university system; desire to enhance the learning experience of undergraduates; and motivation to increase the prominence of the discipline of developmental biology in our university. We engineered a novel, multi-year undergraduate developmental biology program which was "student-oriented," ensuring that students were continually exposed to the underlying principles and philosophy of this discipline throughout their undergraduate career. Among its key features are introductory lectures in core courses in the first year, which emphasize the relevance of developmental biology to tissue engineering, reproductive medicine, therapeutic approaches in medicine, agriculture and aquaculture. State-of-the-art animated computer graphics and images of high visual impact are also used. In addition, students are streamed into the developmental biology track in the second year, using courses like human embryology and courses shared with cell biology, which include practicals based on modern experimental approaches. Finally, fully dedicated third-year courses in developmental biology are undertaken in conjunction with stand-alone practical courses where students experiencefirst-hand work in a research laboratory. Our philosophy is a "cradle-to-grave" approach to the education of undergraduates so as to prepare highly motivated, enthusiastic and well-educated developmental biologists for entry into graduate programs and ultimately post-doctoral research.     

Craniofacial variability and modularity in macaques and mice

Evolutionary developmental biology of primates will be driven largely by the developmental biology of the house mouse. Inferences from how known developmental perturbations produce phenotypic effects in model organisms, such as mice, to how the same perturbations would affect craniofacial form in primates must be informed by comparisons of phenotypic variation and variability in mice and the primate species of interest. We use morphometric methods to compare patterns of cranial variability in homologous datasets obtained for two strains of laboratory mice and rhesus macaques. C57BL/6J represents a common genetic background for transgenic models. A/WySnJ mice exhibit altered facial morphology which results from reduction in the growth of the maxillary process during formation of the face. This is relevant to evolutionary changes in facial prognathism in nonhuman primate and human evolution. Rhesus macaques represent a nonhuman primate about which a great deal of phenotypic and genetic information is available. We find significant similarities in covariation patterns between the C57BL/6J mice and macaques. Among-trait variation in genetic and phenotypic variances are fairly concordant among the three groups, but among-trait variation in developmental stability is not. Finally, analysis of modularity based on phenotypic and genetic correlations did not reveal a consistent pattern in the three groups. We discuss the implications of these results for the study of evolutionary developmental biology of primates and outline a research strategy for integrating mouse genomics and developmental biology into this emerging field.     

Educating for social responsibility: changing the syllabus of developmental biology

Developmental biology is deeply embedded in the social issues of our times. Such topics as cloning, stems cells, reproductive technologies, sex selection, environmental hormone mimics and gene therapy all converge on developmental biology. It is therefore critical that developmental biologists learn about the possible social consequences of their work and of the possible molding of their discipline by social forces. We present two models for integrating social issues into the developmental biology curriculum. One model seeks to place discussions of social issues into the laboratory portion of the curriculum; the other model seeks to restructure the course, such that developmental biology and its social contexts are synthesized directly.     

Entamoeba histolytica: a snapshot of current research and methods for genetic analysis

Entamoeba histolytica represents one of the leading causes of parasitic death worldwide. Although identified as the causative agent of amebiasis since 1875, the molecular mechanisms by which the parasite causes disease are still not fully understood. Studying Entamoeba reveals insights into a eukaryotic cell that differs in many ways from better-studied model organisms. Thus, much can be learned from this protozoan parasite on evolution, cell biology, and RNA biology. In this review we discuss selected research highlights in Entamoeba research and focus on the development of molecular biological techniques to study this pathogen. We end by highlighting some of the many questions that remain to be answered in order to fully understand this important human pathogen.     

Correlation of ontogenetic and evolutionary processes in view of achievements of modern genetics: Role of gene duplication

I.I. Schmalhausen’s concept about the interrelation of individual and historical development is analyzed from the positions of modern developmental biology and molecular genetics. The role of gene duplication in evolutionary, ontogenetic, and adaptable processes is discussed. The data on mechanisms of functional diversification of duplicated genes (exon-intron structural changes and point mutations) in these processes are submitted. The modern synthesis outlook in developmental biology is regarded.