Phreatichthys andruzzii, lateral view (left), frontal view (right)

Adaptations of some fish species to their environment can be most peculiar, especially within cave dwelling kinds. The so called troglomorphisms slowly turn these fish into almost grotesque looking creatures with no eyes, lost pigments and no scales on the one hand, but with enhanced alternative sensory systems on the other hand.

Cavefish of different orders have been found in cave systems from Mexico to China, all revealing different degrees of adaptations to their life underground. One astonishing example for extreme troglomorphism is represented by the species Phreatichthys andruzii. These fish have been living for about 2 million years in complete darkness in a place, where one would not expect swimming fish at all: under the Somalian desert. Due to this total isolation from surface streams, adult P. andruzzii exhibit full regression of eyes, scales and pigments (see pictures). Remarkably, and similar to the well studied Mexican cavefish Astyanax mexicanus, eyes start to develop during embryogenesis following the stereotypic patterning of eye field determination and subsequent evagination, forming the optic cups. Despite the effort, apoptosis is initiated in later stages and ultimately leads to the loss of the organ. Both species have clearly been evolving separately from each other in two different continents, but concerning the eye loss, the outcome is very similar.

Thus in order to investigate, whether the development is similar on the molecular level as well, or if there maybe are differences, we started an intensive in situ hybridization (ISH) study of key transcription factors and components of regular vertebrate eye development (based on zebrafish and medaka). In the cavefish Astyanax it has been shown that midline signalling of shh (sonic hedgehog) is expanded in early developmental stages, when the eye field is forming, which leads to dysregulation of subsequent transcription factor expression and guidance. When we analysed the early developmental stages of P. andruzzii, we could not detect any obvious deviation of transcription factor patterning and corresponding eye formation. Moreover, when we looked at later stages, we even detected an establishing ciliary marginal zone (CMZ), the teleost stem cell niche of the eye. This observation is further supported by anti-PCNA immunohistochemistry, revealing active proliferation in the CMZ. Taken together, until the onset of further differentiation, the early patterning and formation of the Phreatichthys eyes proceed as in surface species like D. rerio.

From this stage onwards, normal morphogenesis of the vertebrate eye is accompanied by highly stereotypic differentiation of retinal progenitor cells (RPCs), which results in the characteristic layering of the eye. Retinal ganglion cells (RGCs) are born first, 
followed by horizontal, amacrine and bipolar cells and the late-born rod and cone photoreceptors, as well as non-neuronal Müller glia cells. Since no discrete layering of the cavefish retina has been observed at any time point, we studied this developmental phase by addressing cell type specific transcription factor genes with ISH. Our data revealed that only the first born RGCs are established, but not maintained. Detailed analysis of processes of these neurons also revealed no connection to the optic tectum, rendering them functionless. This disruption of the typical differentiation cascade consequently inhibits generation of further cell types and no layering occurs.

Furthermore, we detected massive apoptotic events spreading over the entire neuroretina from this time point onwards, which might very well be triggered by the dysregulated differentiation, in order to protect the eye against aberrant proliferation. Thus, we speculate that a simple differentiation block building on intrinsic control mechanisms elegantly eliminates the Phreatichthys retina.

In comparison to Astyanax, a different strategy is being followed to eradicate the eye during embryogenesis, which specifically blocks differentiation and layering of the neuroretina. In several Astyanax populations this layering proceeds, but apoptosis eventually intervenes, too. By studying these diverse modes of eye degeneration within cavefish species, light can be shed on the different developmental checkpoints and how they are controlled in normally developing vertebrate eyes.

Photographs courtesy of Luca Scapoli.
Stemmer, M., Schuhmacher, L., Foulkes, N., Bertolucci, C., & Wittbrodt, J. (2015). Cavefish eye loss in response to an early block in retinal differentiation progression Development, 142 (4), 743-752 DOI: 10.1242/dev.114629

One postdoctoral and one technician positions, both fully funded for 3 years, are available in the laboratory of Dr. Natalia Sanchez-Soriano at the Institute of Translational Medicine, Department of Cellular and Molecular Physiology, University of Liverpool, UK. We are seeking highly motivated, collaborative, interactive but independent candidates to study fundamental microtubule- and transport-related mechanisms underlying the formation and maintenance of axons and synapses, and their links to neurodegeneration. Ideally, applicants should be trained in neuro- and/or cell biology, molecular biology and imaging, and have experience with the model organisms Drosophila. For more information about our group see https://sanchezlab.wordpress.com

The laboratory benefits from a highly interactive scientific environment in the Department of Cellular and Molecular Physiology at the University of Liverpool, and an outstanding neurobiology community in the Northeast of England. In addition, Liverpool offers broad cultural and recreational opportunities. Interested candidates should email Natalia Sanchez-Soriano (Natalia1 [at] liverpool.ac.uk) with a statement of interest together with a CV.

Time for the slightly delayed third round of images from the 2013 Woods Hole embryology course! Below you will find 4 beautiful images from the course. Choose the one you would like to see in the cover of Development by voting on the poll at the end of the post (you can see bigger versions by clicking on the images). The poll is set up to allow only one vote per person, so please stick to this rule to give all the images a fair chance!

Voting will close noon GMT on March the 2nd.

1. Scanning electron micrograph of a black scale from the butterfly, Papilio blumei. Visible is the elaborately sculptured lattice between the microrib-covered ridges. Acting in concert with melanin inside the scales, these scale cuticle nanostructures are thought to contribute to making these scales exceptionally black by trapping light through internal reflection. Imaged on a Zeiss Supra40VP SEM. Distance between ridges is approximately 2 µm. This image was taken by Lara Linden (Duke University, USA).

2. Blastoderm stage Drosophila melanogaster embryo. In situ hybridization for the 5’ end of Scr in yellow, Antp in blue (from the P1 promotor, 5’ in the first intron), and a previously uncharacterized lincRNA in pink. Imaged on a Leica SP8 confocal. This image was taken by Wiebke Wessels (James Cook University, Australia).

3. Living embryo of the little skate (Leucoraja erinacea) sitting atop its yolk at approximately ten weeks of development. Imaged on a Zeiss Discovery.V20. This image was taken by Mary Colasanto (University of Utah, USA) and Emily Mis (Yale University, USA).

4. Wing of the Blue Mountain Swallowtail (Papilio ulysses). The blue scales seen here contain no blue pigment, rather the physical interaction of light with cuticle-based nanostructures of the scale creates a metallic blue color. Imaged on a Zeiss Discovery.V20 with image planes stacked using Helicon Focus. This image was taken by Emily Mis (Yale University, USA) and Misty Riddle (UC Santa Barbara, USA).

Here are the highlights from the current issue of Development:

Pathways to human hypothalamic neurons

The dysfunction of hypothalamic neurons is implicated in a number of common diseases, including obesity, hypertension, and mood and sleep disorders. To date, studies of human hypothalamic neurons have been limited due to their inaccessibility, but now (on p. 633), Florian Merkle, Kevin Eggan, Alex Schier and colleagues use two complimentary techniques to differentiate human pluripotent stem cells (hPSCs) into an array of neuropeptide-producing hypothalamic neurons. In the first approach, the researchers use a self-patterning strategy to generate hypothalamic progenitors from hPSCs (both embryonic stem cells and induced pluripotent stem cells). The subsequent maturation of these progenitors leads to the generation of neuropeptide-producing neurons that are morphologically similar to their in vivo counterparts. In the second, more readily scalable approach, the researchers direct the differentiation of hPSCs into hypothalamic progenitors by modulating pathways known to play a role in hypothalamic development. These progenitors, they report, can also be matured into neuropeptidergic neurons that adopt the gene expression profiles and morphological properties of their counterparts in the human brain. Finally, the authors demonstrate that in vitro-derived human hypothalamic neurons are able to integrate into the mouse brain and continue to express hypothalamus-specific neuropeptides. The cells generated by these approaches thus offer a promising tool for disease modelling, drug screening and therapeutic cell transplantation.

Plant embryogenesis: the ins and outs of auxin flow

Directional transport of the plant hormone auxin plays an essential role in plant development. To date, most studies of auxin transport have focussed on the PIN family of auxin efflux transporters but now Jiri Friml and colleagues show that the AUX1 and LIKE-AUX1 (LAX) auxin influx carriers are required during plant embryogenesis (p. 702). The researchers first demonstrate that the pharmacological inhibition of auxin influx in both microspore-derived Brassica napus embryos and Arabidopsis thaliana embryos results in defects in early embryogenesis. They further reveal thatAUX1, LAX1 and LAX2, but not LAX3, are expressed during Arabidopsis embryo development. These differentially expressed influx carriers, they report, are required for correct embryo development; patterning defects and defective cotyledon and root formation are observed inaux1 lax1 lax2 triple mutants. Further genetic interaction studies reveal that aux/lax and pinmutations have additive effects on cotyledon development, suggesting that AUX/LAX carriers act in concert with PIN transporters. Finally, the researchers uncover a positive-feedback loop between MONOPTEROS-dependent auxin signalling and auxin transport, highlighting a role for balanced and regulated auxin influx and efflux during plant development.

Morphogenesis in full force

Convergent extension (CE) is a morphogenetic process that shapes the early vertebrate embryo. During CE, embryonic tissues elongate along one axis while narrowing in the other, but how are the appropriate forces generated and regulated during this event? Here, Lance Davidson and colleagues investigate the mechanical control of CE in Xenopus embryos (p. 692). They develop a new method for measuring tissue-scale force production, which involves embedding embryonic tissues in a gel-based force sensor. Using this approach, they report that force production during CE is regulated by myosin II contractility; reduced elongation rates are seen when tissues are treated with a ROCK inhibitor but, surprisingly, these are only evident when tissues are challenged with the mechanical constraints of the gel. By altering gel composition, the researchers further demonstrate that CE is adaptive and can accommodate to stiffer microenvironments, suggesting that mechanical feedback produces greater stresses to overcome the constraints of the gel. Finally, they report that the notochord does not contribute to force production, whereas the paraxial mesoderm and prospective neural tissues are major contributors to elongation forces. This study thus sheds light on the mechanical control of CE and offers an exciting new tool that can be used to probe force production in developing tissues.

Lending weight to mitochondrial transmission

Over-nutrition and obesity during pregnancy are known to result in lasting developmental and metabolic consequences in offspring. Here, using the Blobby mouse model for obesity, Rebecca Robker and co-workers (p. 681) probe the mechanistic origins of these changes and test if they are reversible. They demonstrate that obese females produce cumulus oocyte complexes that exhibit changes in gene and protein expression associated with ER stress. They further show that oocytes from obese mice contain normal levels of mitochondrial (mt) DNA, but display reduced mitochondrial membrane potential and higher levels of autophagy compared with control oocytes. Following in vitro fertilization, the oocytes from obese mice form blastocysts that contain reduced levels of mtDNA and exhibit reduced developmental potential. When transferred to normal-weight surrogates, these blastocysts give rise to foetuses that are heavier than controls and exhibit reduced mtDNA content in the kidney and liver. Importantly, many of these obesity-dependent changes in oocyte characteristics and developmental potential can be reversed by treatment with ER stress inhibitors. Together, these studies demonstrate that obesity induces mitochondrial dysfunction that is transmitted to offspring, and that these defects can be alleviated by using interventions prior to conception to improve embryo and foetal development.

Vascular patterning goes out on a limb

During limb morphogenesis, developing digits are initially interconnected by soft tissue but then become separated as this tissue undergoes programmed cell death (PCD) and regresses. Now, Elazar Zelzer and co-workers demonstrate that vascular patterning in the mouse limb regulates interdigital cell death by a reactive oxygen species (ROS)-dependent mechanism (p. 672). They demonstrate the presence of a complex and high-density capillary network within interdigital regions at the onset of PCD; by contrast, the developing digits are unvascularized. As PCD progresses, they report, the vasculature concomitantly becomes remodelled. They further show that a decrease in interdigital blood vessel numbers, induced by inactivating VEGF in the limb mesenchyme, inhibits PCD. By contrast, hypervascularization following VEGF overexpression in the limb leads to elevated PCD and an expansion of the domain in which PCD occurs. Finally, the researchers demonstrate that interdigital PCD is dependent on oxygen and the production of ROS. Together, these findings highlight a novel function for vascular patterning, and suggest the existence of a mechanism by which vascularization of interdigital regions leads to an increase in tissue oxygenation, which in turn triggers ROS production and PCD.

Activin/Nodal signalling in stem cells

Activin/Nodal growth factors control a broad range of biological processes, including early cell fate decisions, organogenesis and adult tissue homeostasis. Here, Siim Pauklin and Ludovic Vallier provide an overview of the mechanisms by which the Activin/Nodal signalling pathway governs stem cell function in these different stages of development. See the Review on p. 607

 

The melanocyte lineage in development and disease

Melanocytes have an apparently simple aetiology, differentiating from the neural crest and migrating through the developing embryo to specific locations within the skin and hair follicles, and to other sites in the body. Here, using a cross-species approach, Richard Mort, Ian Jackson and Elizabeth Patton discuss melanocyte development and differentiation, melanocyte stem cells, and the role of the melanocyte lineage in diseases such as melanoma.See the Review on p. 620

Taking the Comparative Invertebrate Embryology course at the Friday Harbor Labs was one of the pivotal experiences of my graduate life, and it was possibly the most valuable, and enjoyable, course I’ve ever taken. I was a student in the course several years ago, when it was taught by two great scientists, Dr. Charles Lambert and Dr. Mark Martindale (it is taught by different instructors every year). I loved seeing the amazing diversity of marine invertebrate embryos and larvae, and watching their development in real time, after collecting the animals from their natural habitats. One of the things I especially appreciated about the course is that it gave me an opportunity to watch and observe organisms closely, on their own terms, rather than immediately trying to convert them into data points to answer a specific question. This let me see aspects of the embryos and larvae that I would not have noticed otherwise.

The Friday Harbor embryology course transformed my research path. At the time I took it, I was a graduate student working on biomechanics and pattern formation in invertebrate colonies, and was more interested in physiology and marine biology than development. I took the course because I felt a need to get a complete picture of invertebrate biology, and it sounded like fun (it was). I loved the complexity of the larvae, with their muscles, ciliated bands, guts, skeletons, and behavior; but as I watched the embryos transform themselves from egg, to blastula, to gastrula, and beyond, I learned to love them for their own sake. At the same time I gained a feel for their variety and for their natural environments.

So, after finishing my Ph.D., I switched from working on adult animals to working on embryos, focusing on the biomechanics of gastrulation in frogs (with Dr. Lance Davidson), and then struck out on my own to study echinoderm blastula formation. The memory of my experiences at Friday Harbor has continued to shape my research, making me think hard about the kinds of variation organisms have to tolerate in nature, variation due to things like salinity, temperature, and maternal condition. And it made me keenly aware of the diversity of developmental processes within and among animal phyla. This gave me a broad perspective on the mechanics of morphogenesis, and how it relates to development-environment interactions and developmental evolution.

My personal experience in the course led me to my own peculiar niche in developmental biomechanics, but other former students have gone on to study cell and molecular biology, evo-devo, larval ecology, and many other fields. One of the great things about the Friday Harbor course is that it bridges cell and molecular perspectives with ecological and evolutionary perspectives to provide an integrated view of animal development. So the course is very useful for both biologists who wish to understand diversity in developmental modes for ecological or evolutionary studies, and cell and developmental biologists who wish to broaden their knowledge of embryos beyond the standard model systems. The focus is on watching and observing living embryos and larvae from as many different kinds of marine animals as one can get one’s hands on (typically a few species from each of over a dozen phyla).

I loved being a student so much that I jumped at the chance to co-teach the course this summer with Dr. Yale Passamaneck, an excellent evolutionary developmental biologist who has worked with several invertebrate phyla.

Applications are still open, and we have a few spots left that we hope to fill. Applications are needed before February 26th. Financial aid may be available.

If you are interested in the course, please see the course description at: http://depts.washington.edu/fhl/studentSummer2015.html#SumA-4

The course runs from June 15 – July 17, 2015 (5 weeks).

Bone marrow transplants save lives. It’s as simple as that.

The reason bone marrow transplants are so effective is because this squishy tissue is home to haematopoietic stem cells (HSCs), which spend their lives happily producing every single blood cell that will ever circulate around your body.

As a result, if anything goes wrong with your own blood, it is possible to remove your bone marrow (which, for whatever reason, is producing sub-optimal cells) and replace it with somebody else’s which is doing the job just fine.

But it isn’t always quite that straightforward. Finding immunologically compatible tissue isn’t trivial, and there are always more patients needing transplants than there are donors on the list. Also, even if you do manage to find a compatible donor, sometimes their bone marrow just doesn’t contain enough stem cells to be effective.

So, an alternative way of replacing the haematopoietic stem cells in patients with blood disorders is required, and has been the target of many research teams around the globe for years. The golden goal is to be able to generate haematopoietic stem cells in the lab that are genetically matched to the patient, and recent advances in generating induced pluripotent stem cells (iPSCs) from human cells has brought this prospect tantalizingly close – but to date, nobody has managed to successfully generate patient-specific HSCs in the lab.

One major stumbling block in achieving this goal has been a fundamental lack of understanding of how, when and where HSCs actually originate in the first place; how can we possibly attempt to mimic this process in the lab if we don’t know how it works in in a living, breathing organism?

This is exactly the question that scientists in Roger Patient’s lab at the WIMM in Oxford have been asking, and have published their latest findings in Nature Communications.

It is known that during embryonic development of all examined vertebrates, haematopoietic stem cells originate from a layer of arterial cells on the ventral side of the dorsal aorta, known as the haemogenic endothelium [1]. This process is believed to be extremely transient, and is regulated by a complex array of inputs from a variety of signaling pathways, including Wnt16 [2], VegfA [3] and Bmp4 [4].

Role of FGF signalling in the formation of HSCs. Pouget et al, Nature Comms (2014)

Recent research has shown that runx1, a key gene required for emergence of HSCs across many vertebrate species, is directly activated by the Bmp4 signalling pathway in vitro [5], and it is also known that just before definitive (or adult) haematopoiesis is activated in developing embryos, the aortic region switches from a BMP repressive to active environment [4]. However, the mechanism underlying this switch has remained elusive – until now.

Through a series of careful experiments in zebrafish, scientists in the Patient lab have found that the FGF signaling pathway is a negative regulator of HSC emergence via its control of bmp4 activity in the aortic floor, and therefore could be component of the mechanism underlying the switch from a BMP repressive to active environment that is required for HSC emergence.

Not only do these findings add a crucial piece to the puzzle in understanding how HSCs develop in vivo, but could also help to develop more efficient strategies to generate patient-specific haematopoietic stem cells in the lab.

The original research article was published in Nature Communications in November 2014: FGF signaling restricts haematopoietic stem cell specification via modulation of the BMP pathway

This post was written by Bryony Graham (@bryony_g) and was originally published on the WIMM blog.

1. Swiers, G., Rode, C., Azzoni, E., & de Bruijn, M. (2013). A short history of hemogenic endothelium Blood Cells, Molecules, and Diseases, 51 (4), 206-212 DOI: 10.1016/j.bcmd.2013.09.005

2. Clements, W., Kim, A., Ong, K., Moore, J., Lawson, N., & Traver, D. (2011). A somitic Wnt16/Notch pathway specifies haematopoietic stem cells Nature, 474 (7350), 220-224 DOI: 10.1038/nature10107

3. Leung A, Ciau-Uitz A, Pinheiro P, Monteiro R, Zuo J, Vyas P, Patient R, & Porcher C (2013). Uncoupling VEGFA functions in arteriogenesis and hematopoietic stem cell specification. Developmental cell, 24 (2), 144-58 PMID: 23318133

4. Wilkinson, R., Pouget, C., Gering, M., Russell, A., Davies, S., Kimelman, D., & Patient, R. (2009). Hedgehog and Bmp Polarize Hematopoietic Stem Cell Emergence in the Zebrafish Dorsal Aorta Developmental Cell, 16 (6), 909-916 DOI: 10.1016/j.devcel.2009.04.014

5. Pimanda, J., Donaldson, I., de Bruijn, M., Kinston, S., Knezevic, K., Huckle, L., Piltz, S., Landry, J., Green, A., Tannahill, D., & Göttgens, B. (2007). The SCL transcriptional network and BMP signaling pathway interact to regulate RUNX1 activity Proceedings of the National Academy of Sciences, 104 (3), 840-845 DOI: 10.1073/pnas.0607196104

9-21 April 2015 Cold Spring Harbor Lab Xenopus course:

Xenopus is an extraordinary in vivo model for cell and developmental biology. The ease of loss- and gain-of-function approaches allows rapid mechanistic analysis; this can be combined with classic embryological manipulations and state of the art imaging. As advances in human genomics rapidly expand our list of novel disease genes, Xenopus is emerging as a powerful, high-throughput system for studying unknown gene function.

For this year’s course, we are fortunate to have two fully funded fellowships for applicants who come from non-standard backgrounds (ie, physics, math, computer science, engineering), as well as several half scholarships for people entirely new to Xenopus.

Informal queries to Karen Liu (karen.liu@kcl.ac.uk) or Mustafa Khokha (mustafa.khokha@yale.edu).

Deadline for applications: 23 February.

http://meetings.cshl.edu/courses/2015/c-xeno15.shtml

In 2014, the British Society of Developmental Biology (BSDB) has initiated the Gurdon Summer Studentship program with the intention to provide highly motivated students with exceptional qualities and a strong interest in Developmental Biology an opportunity to engage in practical research. The 10 successful applicants spent 8 weeks in the research laboratories of their choices, and the feedback we received was outstanding. Please, read the student reports, kindly sent to us by George Hunt.

Modelling Developmental Neurological Disorders and Childhood-Onset Epilepsy in Caenorhabditis elegans

During the summer of 2014 I was a recipient of a Gurdon Summer Studentship awarded by the BSDB. The studentship provided the opportunity to undertake a research project in the Laboratory of Ian Hope at the University of Leeds where I study Biology.

Abnormalities in the development of the central nervous system have been implicated in the epilepsy group of chronic neurological disorders. These disorders affect fifty million people worldwide and are characterized by spontaneous recurrent seizures resulting from excessive, synchronous neuronal activity ^[1,2]. Improving our understanding of the biomolecular basis of epilepsy is of great importance in the search for new therapeutics. Caenorhabditis elegans provides a genetically amenable, and experimentally tractable system to model disease-relevant mutations and was the focus of this study.

Homo sapiens KCNT1 encodes a sodium-activated potassium channel that is widely expressed in the central nervous system and mutations of KCNT1 have been identified in patients with drug-resistant childhood-onset forms of epilepsy. The C. elegans KCNT1 orthologue slo-2 is widely expressed in both neurons and muscle cells ^[3] where it is activated during hypoxia-like physiological conditions by raised concentrations of chloride and intracellular free calcium ^[4]. Protein alignment identified KCNT1 amino acid residues implicated in childhood-onset epilepsy that are conserved from H. sapiens to C. elegans SLO-2. These KCNT1 variants, R474H and R928C, are associated with malignant migration partial seizures in infancy (MMPSI) ^[5] and autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) ^[6], respectively.

In order to generate R474H and R928C epilepsy-associated variants of C. elegans slo-2, equivalent mutations were introduced using the CRISPR-Cas9 system ^[7] to produce novel transgenic strains which can then be used to study the role of these mutations in the development of epilepsy.

Synthetic guide RNAs (sgRNA) were used to direct Cas9 nuclease activity to regions of the slo-2 locus in close proximity to the target mutational sites. Cas9-mediated cleavage generates double-stranded DNA breaks (DSBs) that are repaired in vivo by either homology-directed repair (HDR), using a homologous template, or by non-homologous end joining (NHEJ), which generates short insertion/deletion (indel) mutations. To incorporate the epilepsy-linked point mutations into the C. elegans genome, worms were microinjected with plasmid vectors expressing the modified sgRNAs and Cas9 alongside slo-2 fragments that had been PCR mutagenized to include the desired point mutations. This generated DSBs at the slo-2 locus followed by HDR to mend the DSB and introduce the desired point mutations.

From fifteen F₀ hermaphrodites injected, I obtained twenty-eight transgenic F₁ individuals. Ten of these produced transgenic progeny and ten independent transgenic strains were established of which six had been targeted with the R474H equivalent alteration and four with the R928C equivalent. Microinjected DNA forms large extra-chromosomal arrays that are not transmitted to all progeny in a brood and the rate of successful CRISPR-Cas9 alterations in C. elegans varies depending on target loci ^[7]. To screen transgenics for alterations of slo-2, I performed single worm PCR on progeny of transgenic individuals to amplify slo-2 fragments containing the target mutation loci and assayed fragment length for the presence of indels by agarose gel electrophoresis. Following CRISPR-Cas9 generation of a DSB, activation of the NHEJ repair pathway can produce short indels at the repaired loci, providing a useful method for confirming successful CRISPR-Cas9 activity. Smaller than expected slo-2 fragments were detected in the progeny of transgenic individuals from three different strains; however, further extensive screening is required to determine whether these represent deletions within slo-2 or non-target amplification. Following confirmation of the efficacy of the CRISPR-Cas9 system the next step will be sequencing of slo-2 to identify mutants with the desired epilepsy-linked point mutations.

The transgenic and mutant strains will provide a useful resource in further studies of the biomolecular basis of drug-resistant childhood-onset epilepsies as they should allow production of the specific genomic modifications sought in slo-2. The effects of the slo-2 mutations on the functioning of the C. elegans neuromuscular system would then need to be characterized and findings could provide improvements in our understanding of how specific KCNT1 variants give rise to epilepsy. This research will contribute to an existing network of KCNT1 research currently being undertaken by Jonathan Lippiat and Steve Clapcote at the University of Leeds.

Overall, the BSDB Gurdon Summer Studentship provided a great opportunity to experience working in a professional research laboratory, and has strongly reinforced my desire to pursue a career in research.

References:

[1] Kwan, M.D. Schachter, S.C. and Brodie, M.J. (2012) Drug-Resistant Epilepsy. The New England Journal of Medicine 365, 919-926

[2] Engel, J.E.R. (2013) Seizures and Epilepsy (2nd Edition), New York: Oxford University Press

[3] WormBase web site (2014) Release: WS244 — [LINK]

[4] Santi, C. et al. (2003) Dissection of K⁺ currents in Caenorhabditis elegans muscle cells by genetics and RNA interference. PNAS 100, 14391-14396

[5] Barcia, G. et al. (2012) De novo gain of function KCNT1 channel mutations cause malignant migrating partial seizures of infancy. Nature Genetics 44, 1255-1259

[6] Heron, S.E. et al. (2012) Missense mutations in the sodium-gated potassium channel gene KCNT1 cause severe autosomal dominant nocturnal frontal lobe epilepsy. Nature Genetics 44, 1188-1190

[7] Friedland, A,E. et al. (2013) Heritable genome editing in C. elegans via a CRISPR-Cas9 system. Nature Methods 10, 741-743

Our jobs page has been busy this month, with several new postdoc positions advertised. Here are some of the other highlights:

Research:

– Christoph and his colleagues wrote about their recent Development paper, where they inhibited the Rho-kinase ROCK in the rabbit embryo, discussing the implications of their work in our understanding of the evolution of vertebrate gastrulation.

– and Chistele’s latest Stem Cell Beauty post focused on a Stem Cell Reports paper where Meinhardt and colleagues embed embryonic stem cells in a 3D matrix to generate 3D neuroepithelial cysts.

Meetings:

– Do you want to attend the Abcam Adult Neurogenesis meeting in Dresden for free? Then apply to become the official meeting reporter!

– and the newly created Pan-American Society for Evolutionary Developmental Biology is running their first meeting this August.

The Node survey:

The Node was launched almost 5 years ago, and it is now time to revise its design and functionalities. Help us develop the Node for the future by answering a few questions in our survey. To thank you for your time, at the end of the survey you can choose to enter a prize draw to win a bag of goodies from the Node and Development!

Also on the Node:

– Our latest model organism post comes all the way from Dunedin in New Zealand! Read Megan’s post ‘A day in the life a honeybee lab‘!

– There are many ways to get involved in science outreach. We have reposted a Development Spotlight article on this topic.

Happy reading!