My name is Idoia, I am a PhD student within the Brainshark group at the University of Santiago de Compostela (Spain). I am currently finishing a research stay at the University of Edinburgh (Scotland) funded by the travelling fellowships offered by the Company of Biologists.

It is being four years since I started my predoctoral period. During this time, I have considered several times to carry out an international experience but never found the right moment. Now, just in the final stages of my thesis, I though “now or never”, and here I am, in a wonderful wild place called Scotland.

This stay had involved many changes for me. Language, culture but, most of all, a change in the animal model I work with: from shark to mouse. In our lab in Santiago de Compostela, we use the shark Scyliorhinus canicula (also called lesser-spotted dogfish) as a model for developmental studies of the nervous system. Yes, a shark! Ok, a small one, but still a shark. We are interested in the evolutionary changes that have occurred in the developing and adult nervous system throughout vertebrate phylogeny but also in the analysis of the conserved traits between different animal groups. Analyzing shared and derived features in our model is yielding interesting data like the presence of neuronal tangential migratory routes in the developing telencephalon of sharks homologous to those described in other vertebrates.

I will start by answering the first question that people used to ask me whenever I go to a conference: “why sharks?” Of course, the phylogenetic position of cartilaginous fishes is crucial to assess the ancestral condition of the vertebrate brain. Moreover, in the last decades, there has been an increasing interest in the dogfish as a model for developmental studies. This is due to it presents some advantages with respect to other vertebrate groups which allow a detailed analysis of developmental processes. For example: external egg gestation and transparent eggs (easy accessibility to the embryo to the implementation of different experimental approaches), protracted embryonic development (gestation period from 6 to 8 months), large size of the embryonic brains and availability of embryos at any time of the year. See the eggs in figure 1. Moreover, unlike teleost fish (as zebrafish, the main fish model nowadays), the telencephalon of cartilaginous fish develops by a process of evagination instead of eversion wich allows more reliable comparisons with other vertebrates. In fact, many people cannot distinguish at a glance a shark embryo from a mouse one. Do you want to try? See figure 2.

In the last years, we have been studying the expression patterns of Pax6, a well-conserved transcriptional factor, during forebrain development in sharks. Some open questions in our investigation made us to contact to Dr David Price, in the University of Edinburgh, and propose him a short collaboration. He kindly accepted to having me at least for three months in his lab to check our hypothesis in a different model as well as to help in other aspects of his ongoing project on Pax6.

At the beginning was tricky, working with mice was a big challenge for me; but at the same time was amazing to do research in a species in which several optimized techniques are available. Particularly I enjoyed learning slice culture techniques and I hope to have time to implement them in shark embryos and perform some axon guidance experiments upon my return.

On the other hand, the non-academic experience was also terrific. I loved Scotland, their people, their accent, landscapes, music and traditions. This is a real beautiful corner of the world you have to visit at least once in life. Of course the weather was not the best thing but I have to say that it was way better than I was told.

But maybe the best thing I obtained from this experience is the personal enthusiasm impulse to face the final stage of my predoctoral period. It has been one of the best decisions I have made, without a doubt whatsoever, and I have to sincerely thank to the Company of Biologists for their support.

You have reached the end of the advent calendar! Please see the round-up of all entries here.

Happy holidays!

If you have been following along with the advent calendar we’ve had in the sidebar for the past couple of weeks, you will have seen twenty-four papers – all selected by readers of the Node.

We’ve seen a diverse selection of papers, all describing recent work in developmental and stem cell biology. The people who suggested the papers wrote a brief description of the work, and why they chose it. Those little recommendations added an extra dimension to what otherwise would just have been a list of papers.

For example, on December 16 we featured a paper on pigmentation patterns in cats. Heather Etchevers, who selected the paper, wrote: “this paper was justifiably published in a general science journal because to some extent, everyone has asked themselves the question of how the leopard got its pattern of spots.” On December 24, Tohru Yano excitedly described a paper on limb development: “This paper shows us crazy results of extra fins/limbs at the same position!” And near the start of the month, on December 5, Bob Goldstein wrote “an important step forward, and beautiful!” about a recent paper on neural tube closure imaging.

We got a lot of great feedback about the advent calendar, but of course it was all down to your select not papers. So a big thank-you to everyone – from grad students to professors – whose suggestions were included. In order of appearance on the calendar: Nishal Patel. Tohru Yano, Rachael Inglis, Mary Todd Bergman, Bob Goldstein, Eva Amsen, Nik Papageorgiou, Katherine Brown, Heather Etchevers, Claire Cox, Barry Thompson, Heather Buschman, Andrew Renault, Seema Grewal, Benoit Bruneau, the Raff Lab, and Joanna Asprer.

Another round of special thanks goes to the journals who temporally freed access to papers so that our advent picks were available to everyone on their respective days. Thank you very much to Developmental Dynamics, Cell, Science Translational Medicine, Current Biology, Developmental Cell, Science, Genes & Development, Nature, and Development.

If you missed any of the entries, you can find the archive here. Some of the papers are no longer free to access, though.

Finally, the complete list of all the papers we’ve featured these past weeks:
(more…)

Today’s recommended paper is:

Transient downregulation of Bmp signalling induces extra limbs in vertebrates
Bea Christen et al. (2012)
Development 139 (14), 2557-2565

Submitted by Tohru Yano:
“This paper show us crazy results of extra fins/limbs at the same position! I believe both these funny observations and finding of developmental mechanisms are needed in the field of developmental biology or stem cell biology in this hurry-scurry age.”

From December 1 to 24 we are featuring Node readers’ favourite papers of the past year. Click the calendar in the side bar each day to see a new paper. To see all papers submitted so far, see the calendar archive.

The UPMC/Curie Institute International Course in Developmental Biology took place in Paris during five weeks.

Students coming from Master or PhD programs around the world gathered together for the three first weeks to participate to the practical part. The group was composed of approximately 20 people from France, Portugal, the Netherlands, Ireland, India, Greece, the USA and China. UPMC Developmental Biology groups animated workshops specialized in each animal model: Drosophila, Mouse Oocytes, Mouse embryos, Chicks embryos, Xenopus, Zebra fish and Nematode.

The high quality of available and hands-on specialists together with complete and modern materials for each bench offered impeccable conditions to get an intense knowledge from every model presented.

Our group was directed everyday (with the exception of Sunday) by three to five Professors or Assistant Professors recruited among the best French specialists in their domains. This provided a true atmosphere of work, and by the end of long days, we were both exhausted and still amazed by all the possibilities in developmental biology that we had approached with each model.

After these first three weeks, began the second part of the program: conferences given by French and International speakers at the Curie Institute. In the heart of historical Academic Europe – Paris Latin Quarter – we had the chance to participate to seminars given by some of the most exciting biologists, coming from Harvard, Cambridge, the Stowers Institute, UPMC, etc. Their reputation in their fields of research crossed the program’s frontiers and brought many scientists from other domains coming to join us occasionally, standing all along, like in concerts of superstars!

Very recent research topics in development were presented, from plant biology to planarian regeneration, from induced pluripotent stem cells to limb bud development. After every conference, we had enough time to ask questions, so that it was more informal conversations between the speaker and us. Then we could talk face to face about everything, their research of course, but also their point of views about everything, such as their career, the choices they made… all this, with coffee and croissants.

Every couple of days, a group of three of us was to present an article and to design an experimental research plan to deepen the subject of the day. It was a good opportunity to practice skills in presenting conferences, right within this total immersion in science communication.

The intensity of the program enabled us to get to know each other very quickly. Little talks about science or our lives as international students began to build a common experience in our shared interest in developmental biology. By the end of the program, not only we had acquired scientific skills in theory, methods and practicals, but also we became friends and started to build a strong network of future developmental scientists.

Today’s recommended paper is:

Inhibition of SRGAP2 Function by Its Human-Specific Paralogs Induces Neoteny during Spine Maturation
Cécile Charrier et al. (2012)
Cell 149 (4), 923-935

Submitted by Joanna Asprer:
“The paper shows that a human-specific paralog of SRGAP2 may have played a role in human evolution by promoting the formation of denser and longer dendritic spines during cortical development.”

From December 1 to 24 we are featuring Node readers’ favourite papers of the past year. Click the calendar in the side bar each day to see a new paper. To see all papers submitted so far, see the calendar archive.

Today’s recommended paper is:

Cartwheel architecture of Trichonympha basal body
Paul Guichard et al. (2012)
Science 337 (6094), 533

Submitted by the Raff lab:
“We chose this paper because by finding an unusual organism, which had such a long centriole, they managed to answer a fundamental question in the centrosome field, for which we thought there would never be an answer for (namely whether the cartwheel of a centriole is a spiral or a stack of rings).”

From December 1 to 24 we are featuring Node readers’ favourite papers of the past year. Click the calendar in the side bar each day to see a new paper. To see all papers submitted so far, see the calendar archive.

Today’s recommended paper is:

Protocadherins mediate dendritic self-avoidance in the mammalian nervous system.
Julie L. Lefebvre et al. (2012)
Nature 488, 517-521

Submitted by Seema Grewal:
“This paper shows that that Pcdhs in the mammalian nervous system provide the basis for neuronal recognition during dendritic self-avoidance, similar to the way in which Dscam isoforms control self-avoidence in fly neurons.”

From December 1 to 24 we are featuring Node readers’ favourite papers of the past year. Click the calendar in the side bar each day to see a new paper. To see all papers submitted so far, see the calendar archive.

This book review originally appeared in Development. Tatsumi Hirata reviews “Neuronal Guidance: The Biology of Brain Wiring ” (Edited by Marc Tessier-Lavigne and Alex L. Kolodkin).

Book info:
Neuronal Guidance: The Biology of Brain Wiring. Edited by Marc Tessier-Lavigne, Alex L. Kolodkin. Cold Spring Harbor Laboratory Press (2011) 397 pages ISBN 978-0-879698-97-3 $135 (hardback)

As a graduate student, I learned developmental neurobiology from the Principles of Neural Development (Purves and Lichtman, 1985). This masterpiece textbook taught me the fundamental concepts of how neurons are interconnected, vividly described the historical experimental basis, and introduced me to the exciting field of developmental biology. However, this book is obviously out of date today, particularly since a great number of guidance molecules and pathways have been identified in the meantime, so I have had to look for a good alternative for graduate students and postdocs interested in this field. Neuronal Guidance: The Biology of Brain Wiring completely fulfilled my expectations.

As this book specifically focuses on neural guidance, it might not be an appropriate textbook for undergraduate students with a broad interest in developmental biology, but it will provide a very good read for postgraduates who have some experience in neurobiology or who are keen to have a research career in this or related fields. It will also be very useful for senior investigators wanting to catch up with the latest data in the field.

Following a brief primer written by the editors, Marc Tessier-Lavigne and Alex L. Kolodkin, the book is organized into 19 chapters, each contributed by experts on the topic. Initially, I was somewhat afraid that this style might make the book a selective collection of highly specialized reviews, but, thanks to the thoughtful choice of topics and contributors, the book is, in fact, much more comprehensive than I anticipated.

The chapters are grouped into three sections, each on a different aspect of neural guidance. The first chapter, by Jonathan Raper and Carol Mason, is entitled ‘Cellular strategies of axon pathfinding’, and provides a good basic overview of the history of axon guidance research and the general concepts obtained therefrom. The following eight chapters in this first section describe comprehensive guidance strategies in traditional and new models of nervous systems. These include chapters on such as visual map development by David A. Feldheim and Dennis D. M. O’Leary, nervous system midline crossing by Barry J. Dickson and Yimin Zou, and dendrite and axon tiling by Wesley B. Grueber and Alvaro Sagasti. A little unexpected is the inclusion of the chapter entitled ‘Human genetic disorders of axon guidance’ by Elizabeth C. Engle, which effectively provides a fresh perspective on this topic.

The second section of the book includes five chapters dealing with intercellular signaling in neural guidance. This section is more detailed than the first part of the book, and is devoted to the introduction of many molecules and their signaling pathways, reflecting the rapid expansion of this field in recent years. Among the chapters here, ‘Signaling from axon guidance receptors’ is a clear overview presented by Greg J. Bashaw and Rüdiger Klein, and ‘Trafficking guidance receptors’ by Bettina Winckler and Ira Mellman describes a topic that is not always covered in axon guidance books and is informative to read.

The final section introduces other cellular processes that use common guidance signals. Several of these topics are already familiar to developmental neurobiologists, such as those described in the chapters on neural cell migration by Oscar Marín and colleagues, axon pruning by Pierre Vanderhaeghen and Hwai-Jong Cheng, and axon regeneration by Roman J. Giger and colleagues. These authors very successfully provide a good, broad perspective to the reader.

Overall, the selection of topics is well balanced, and the chapters are arranged to accurately represent the current scenario in research on neural guidance. Although a few chapters seem a little too specific for people with interests outside of that particular subdiscipline, most are written in a coherent holistic manner to provide a broad overview of our current understanding of neural guidance.

Some topics are repeatedly discussed in several sections of the book. This is the case with guidance molecules such as netrin, semaphorins, slits and ephrins, which function in various systems. Nevertheless, the overlap in the content between chapters is kept to a minimum. I prefer this approach, as it helps the reader to understand, in a step-by-step manner, how the nervous system is systematically constructed by multiple guidance signals. This makes the book more suitable to providing an understanding of the underlying biology, rather than comprising a thick directory of guidance molecules listed with location and time of action.

One feature that really impressed me is that most chapters devote a lot of attention to historical background and the description of general concepts that have led to the current state of research in the field. As mentioned above, several major principles of neural development were already established by 1985, when the classic text Principles of Neural Development was published, even though support in the form of molecular data was lacking at that time. Surprisingly, the subsequent identification of many guidance molecules and their signaling pathways has barely challenged these classic principles. Rather, new findings have confirmed established models, and, in fact, identification of most guidance molecules was based on general deductions from these principles. For example, the identification of ephrins was inspired by the historic transplantation experiments conducted on the retinotectal system by Roger Sperry and others: researchers looked for the magic chemoaffinity label that, according to theory, would form a ‘gradient’ over the tectum, and identified ephrins, which possessed exactly the predicted properties (Cheng et al., 1995; Drescher et al., 1995). Neuronal Guidance: The Biology of Brain Wiring pleasantly reminded me of such links between historic concepts and the latest data on molecular mechanisms. Realization of such connections will clarify, especially to newcomers in this field, the real significance of ongoing studies.

In summary, Neuronal Guidance: The Biology of Brain Wiring achieves a good balance between basic principles and leading cutting-edge research and will prove to be an excellent introductory text for students and postgraduates who are curious about this branch of developmental biology. The book is also refreshing for old hands: after reading it, I felt full of new ideas.

Today’s recommended paper is:

Growing Microtubules Push the Oocyte Nucleus to Polarize the Drosophila Dorsal-Ventral Axis
Tongtong Zhao, Owen S. Graham, Alexandre Raposo and Daniel St Johnston (2012)
Science 336 (6084), 999-1003

Submitted by Andrew Renault:
“An example of purely basic research, using beautiful live imaging to overturn previously held ideas about how an oocyte nucleus is repositioned to break radial symmetry.”

From December 1 to 24 we are featuring Node readers’ favourite papers of the past year. Click the calendar in the side bar each day to see a new paper. To see all papers submitted so far, see the calendar archive.