In the late eighties, the tools and concepts of molecular biology began to invade the field of embryology, leading to a revolution in our understanding of the molecular principles that underlie organismal development. From this revolution arose several defining concepts, such as the conservation of the molecular toolkit that organises the body plan of bilaterians. This major overhaul of the field of experimental embryology led to the Journal of Experimental Embryology and Morphology being relaunched as the Development journal we know today.
In the past few years, we have witnessed a second revolution of similar magnitude with the sequencing of the genomes of several of the model species used in developmental studies. A decade ago, developmental biologists were only scratching at the surface of the transcriptome, focusing on the function of a handful of genes. We now know that the quantity of genes at play in developmental processes numbers in the hundreds, if not the thousands. In principle, genome sequences give us access to the entire set of instructions that is used to build the embryo, but, so far, this huge quantity of data has not dramatically increased our knowledge of the genetic control of development. How to comprehend the organisation and functioning principles that underlie the networks of interacting genes and proteins in development remains a challenge for the future. Thus, there are still many exciting discoveries for this field to make.
This genome revolution has also had the less expected consequence of attracting more and more physicists and mathematicians to biology, which has opened the field of development to interdisciplinary approaches. As a result, concepts and methods borrowed from ‘hard sciences’ such as physics are being increasingly applied to studies of developmental biology. This is particularly true for sophisticated cell biological studies, which have benefited greatly from recent innovations and improvements in imaging techniques. Although the central questions that occupy the minds of developmental biologists still remain, such as those concerning the mechanisms of morphogenesis or differentiation, the tools used to explore these questions are becoming increasingly sophisticated and quantitative. I predict that developmental biologists will come to rely more and more on imaging, bioinformatics and genome-wide approaches and will increasingly use standards and concepts from physics to construct meaningful models from experimental data. Consequently, the nature of many developmental biology papers in the future is likely to undergo a drastic change.
The community's increasing use of such quantitative approaches means that it is crucial for us to master the basic tools and concepts to access such papers. Whereas new generations of young scientists who enter the field are likely to be prepared for these changes by their training, the current community of developmental biologists faces a bigger challenge that might deter many of them from utilising these more quantitative approaches. In order to help the community to embrace these new approaches, we will explore ways in which Development can make subjects such as mathematical modelling, bioinformatics or statistics more accessible to developmental biologists. However, although Development must integrate these new approaches into what it publishes, this does not mean that the journal should become a systems biology journal. It should continue to publish excellent developmental biology studies, even very classical ones.
The third revolution in developmental biology has come from stem cell research. It was a thorough understanding of the early stages of mouse development that made the isolation of mouse embryonic stem (ES) cells possible (Evans and Kaufman, 1981; Martin, 1981), a seminal discovery that opened the door to the elegant strategies that have subsequently enabled the vertebrate embryo to be genetically manipulated. These advances also laid the foundation for the isolation of ES cells from human embryos (Thompson et al., 1998), an advance that allows the earliest stages of human development to be investigated in vitro. More recently, Shinya Yamanaka and colleagues have succeeded in reprogramming differentiated cells to an ES cell-like state by expressing a cocktail of four transcription factors (Takahashi and Yamanaka, 2006), revealing that animal cells have an unexpected degree of epigenetic developmental plasticity. Like ES cells, these induced pluripotent (iPS) cells can differentiate into the various derivatives of the three germ layers, thus providing researchers with a means of studying human development in vitro, without the destruction of human embryos. These advances will certainly increase our knowledge of human embryology and will also facilitate the development of in vitro models for many human diseases.
In the past ten years, stem cell research has literally exploded. Although only seven years old, the International Society for Stem cell Research (ISSCR) annual meeting already gathers twice as many participants as the International Society for Developmental Biology (ISDB) congress, the largest meeting in the field of developmental biology. Stem cell biology centres on the identification of stem cells and on understanding their properties of self-renewal and differentiation, issues that also lie at the heart of developmental biology. Thus, stem cell biology is deeply connected to developmental biology. It could be argued that stem cell biology differs from developmental biology because it encompasses a variety of stem cell systems in the adult, such as the skin, hematopoietic system or gut epithelium. However, the molecules and mechanisms that underlie these processes are largely derived from those used in development. Each year, Development publishes influential studies on such adult stem cell systems, for instance on the fly or mouse germline, or gut epithelium or the vertebrate brain or skin, or in various regenerating systems, and should continue to do so (e.g. Casper and Van Doren, 2009; Demehri and Kopan, 2009; Rhiner et al., 2009; Galli et al., 2002; Lee et al., 2009). Although there is currently a temptation to regard stem cell biology as a quite separate field, I believe that reinforcing ties with the developmental biology community would be extremely productive for both fields. The recent breakthroughs in stem cell biology will have a considerable impact on regenerative medicine, bringing closer the prospect of replacing defective or lost cells in a human patient with cells engineered from embryonic or reprogrammed stem cells. In such approaches, stem cells must be faithfully differentiated into the appropriate tissue prior to grafting, following strategies rooted in our understanding of developmental pathways in the embryo. While many stem cell biologists are currently focusing on trying to improve methods to generate pluripotent cells, it is clear that the next major challenge for this field will be to master how to differentiate stem cells into the desired mature tissue. Lessons from development will surely be crucial in achieving this goal, paving the way for clinicians to find new therapies that could help to treat devastating diseases, such as diabetes or muscular dystrophy.
I view stem cell-based regenerative medicine as a major application of developmental biology, providing the long-missing clinical justification for this research field (besides birth malformation studies). Developmental biologists should feel proud to see the stem cell field explode because this is largely owing to their discoveries in fields such as fly genetics and mouse developmental biology. Therefore, I believe that Development should take a clear position in this debate and should promote and advance stem cell research and publish its important findings. To enhance the visibility of Development in this field, I therefore plan to recruit new editors who specialise in stem cell research and, from this issue onwards, Development will feature a new section called ‘Development and Stem Cells’, which will highlight stem cell and stem cell-related research in embryos and adults. This new section will replace the journal's previous ‘Development and Disease’ section.
And what about the fourth revolution? A major challenge that scientific publishing is currently facing is the progressive move towards entirely web-based publishing. This transition period is difficult, and although I certainly think that it will be important to maintain a printed version of Development for those readers who want it, we also need to take bold moves with respect to electronic publishing. Many scientists nowadays do not look at, or have access to, a printed copy of the journal, and hence their only contact with Development is via its website. As such, and in response to feedback that we received in a recent community consultation, Development's website has undergone a major redesign and from this issue will be published on a new platform that will offer the developmental biology community greatly enhanced functionality and navigation and also the kinds of online features and developments the community requested and which we believe leave us well prepared for the revolution to come.
In closing, I would like to take this opportunity to praise the work of my predecessor Jim Smith, who succeeded in strengthening the outstanding publication standards and the impeccable publication ethics of Development in difficult times of increasing competition from newly created journals in the field. I also want to highlight some changes to Development's editorial team, with the departure of four editors. Very special thanks are due to Peter Lawrence, who has accompanied Development through its previous revolutions as an editor for thirty-three years, and who has played a vital role in shaping the journal's vision and ethics. Thanks also to Ginny Papaioannou, who has been instrumental in reinforcing Development's position in the mouse developmental biology community. We are also extremely grateful to Stuart Orkin and Ken Chien, the editors of the ‘Development and Disease’ section for all their hard work in overseeing this special section of the journal for many years.
We also welcome two new editors to Development's editorial board, Nipam Patel, a well-known ‘evo-devo’ specialist, who will help Development to evolve and expand the journal's coverage of this field, and Rong Li, a renowned cell biologist who brings additional expertise to the editorial board in the areas of developmental cell biology and systems biology. Nipam and Rong will be joining a team of highly respected and experienced editors that consists of Ben Scheres, Thomas Lecuit, Steve Wilson, Alex Joyner, Patrick Tam, Liz Robertson, Iva Greenwald, Ken Zaret and Austin Smith, all of whom I congratulate for their outstanding work under Jim's leadership. Lastly, Development would hardly be what it is without the huge contributions of Jane Alfred, Development's Executive Editor. I look very much forward to dealing with all these revolutionary changes with this expert team of editors.