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In Development this week (Vol. 138, Issue 7)

Posted by , on 8 March 2011

Here are the research highlights from the current issue of Development:

A breath of fresh air: miRNAs regulate lung development

Throughout development, a proper balance between the proliferation and differentiation of progenitor cells is essential but the gene regulatory networks that control this balance are only partly understood. Here, Edward Morrisey and colleagues report that miR302/367 (a microRNA cluster) regulates the behaviour of endoderm progenitor cells during mouse lung development (see p. 1235). MicroRNAs (short RNA molecules that silence complementary target mRNA sequences) are expressed in clusters from a single primary transcript. The researchers show that, in early lung endoderm, the miR302/367 cluster is a target of the transcription factor Gata6, which is known to regulate lung endoderm progenitor differentiation and proliferation. Increased or decreased miR302/367 expression, they report, alters the balance of lung endoderm progenitor differentiation and proliferation in part through regulation of the tumour suppressor Rbl2 and the cell-cycle regulator Cdkn1a. Notably, altered miR302/367 expression also disrupts apical-basal polarity of endoderm progenitor cells. Thus, the researchers conclude, miR302/367 directs mouse lung development by regulating multiple aspects of lung endoderm progenitor cell behaviour.

Canonical Wnt9b signals size the kidney

During kidney development, the balance between nephron progenitor cell differentiation and proliferation determines the final number of nephrons and the ability of the kidney to function properly. One current model proposes that Wnt9b/β-catenin signalling induces differentiation in a subset of the progenitors, but that repression of this signal by the transcription factor Six2 is required for renewal of the remaining progenitors. On p. 1247, Thomas Carroll and colleagues challenge this model by showing that Wnt9b/β-catenin signalling is active in both differentiating and renewing progenitor cells in the developing mouse kidney. Moreover, rather than inhibiting Wnt9b signalling in the renewing cells, Six2 acts cooperatively with Wnt9b to elicit progenitor cell expansion. By contrast, in those progenitor cells where Six2 activity is low, Wnt9b/β-catenin signalling induces differentiation. Thus, the researchers propose, the response of progenitor cells to Wnt9b/β-catenin signalling depends on the cellular environment in which the signal is received, and canonical Wnt9b signalling is able to regulate both progenitor cell expansion and differentiation in the developing kidney.

Endoderm specifies germline niche

Interactions between tissue-specific stem cells and their local niche are vital for stem cell self-renewal and differentiation. But how are niches established? On p. 1259, Tishina Okegbe and Stephen DiNardo provide new insights into testis stem cell niche development in Drosophila. The stem cells in the fly testis, which sustain spermatogenesis throughout life, are clustered around a group of somatic cells (hub cells) that serves as a niche. The researchers confirm a previous report that Notch signalling is necessary for specification of mesoderm-derived somatic gonadal precursor cells to the hub cell fate but, unexpectedly, show that the endoderm adjacent to the developing testis supplies the Notch-activating ligand Delta. They also report that niche cell specification occurs earlier than anticipated, well before the expression of known niche cell markers. Given that mammalian primordial germ cells also pass through endoderm on their way to the genital ridge, the researchers suggest that Delta-Notch signalling by the endoderm could be a conserved mechanism for specification of the germline niche.

Glia shape up sensory neurons

Neuronal receptive endings (for example, sensory protrusions) are remodelled by experience; but how do they acquire their new shape? To address this question, Shai Shaham and co-workers have been studying the remodelling of sensory neuron receptive endings that occurs in C. elegans during dauer (a developmental state induced by environmental stressors). They now report that glial cells delimit this remodelling in response to external cues (see p. 1371). Nematodes have two AWC (olfactory) neurons, each of which is enveloped by an amphid sheath (AMsh) glial cell. The researchers show that AMsh glial remodelling is required for the shape changes in AWC sensory neuron receptive endings in dauers, and that glial remodelling requires the AFF-1 fusogen, the transcription factor TTX-1 and probably the VEGFR-related protein VER-1. The expression of ver-1, they report, requires binding of TTX-1 to ver-1 regulatory sequences, and is induced by dauer entry. Together, these results suggest that stimulus-induced changes in glial compartment size spatially constrain the growth of neuronal receptive endings.

Keeping an Eya1 on lung cell polarity

To function correctly, the epithelial cells that line the tubes and air sacs of mammalian lungs need to be polarised. Little is known about the mechanisms that control cell polarity in the lung epithelium but now, on p. 1395, David Warburton and co-workers implicate the protein phosphatase Eya1 in cell polarity control in the mouse distal embryonic lung epithelium, which represents the epithelial progenitor pool. The researchers show that distal embryonic lung epithelium is polarised with characteristic perpendicular cell divisions. They report that several spindle orientation-regulatory proteins and the cell fate determinant Numb are asymmetrically localised in distal embryonic lung epithelium. Furthermore, interfering with the function of these proteins in vitro randomises spindle orientation and alters cell fate. Importantly, the researchers show that interfering with Eya1 function in vivo or in vitro results in defective epithelial cell polarity and mitotic spindle orientation, disrupts Numb segregation, and inactivates Notch signalling, thereby establishing Eya1 as a crucial regulator of the complex behaviour of distal embryonic lung epithelium.

Heartfelt Slit/Robo signals

During vertebrate heart development, myocardial and endocardial precursors migrate towards the embryonic midline where they fuse into a linear heart tube. Now, Jason Fish, Stephanie Woo and colleagues report that a Slit/miR-218/Robo signalling pathway regulates heart tube assembly in zebrafish (see p. 1409). Members of the Slit family of secreted ligands interact with Roundabout (Robo) receptors to provide guidance cues during the development of several organs; development is also regulated by microRNAs (miRNAs) that can fine-tune the expression of developmentally important genes. The researchers show that the conserved miRNA miR-218 is intronically encoded in slit2 and slit3, and that it suppresses Robo1 and Robo2 expression. Further analyses indicate that Slit2, Robo1 and miR-218 are required for the formation of the zebrafish heart tube and that these factors act, in part, by modulating Vegf signalling. These findings reveal a novel signalling pathway for vertebrate heart tube formation and suggest a new paradigm of receptor/ligand regulation in which a ligand-encoded microRNA regulates the expression of its own receptor.

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iPSC timeline

Posted by , on 3 March 2011

Update 23/09/19: Please note that the below piece links to Dipity, a now defunct website. Over at the Drop In Blog you can read the story of what happened to the site. 


 

Science writer Ed Yong put together an interactive timeline of breakthroughs in the field of induced pluripotent stem cells (iPSC), inspired by a manifesto that called for more clarity in the media about the way scientific research is carried out. The timeline puts individual news articles about iPSC into a much broader context.

He only used key publications that were covered in the media, so not all studies are in there, but you can already see a story unfold if you browse along the timeline. Is there any study in particular that you think should be added?

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iPS or transdifferentiation

Posted by , on 2 March 2011

The discovery of iPS made headlines the world over, and rightly so. But recently, transdifferentiation between somatic cell types has also been the focus of  considerable attention. A couple of Nature papers this year have reported that transdifferentiation is even possible between lineages arising from different germ layers – something that not everyone thought could be achieved (see Vierbuchen et al, Nature 463, 1035-1041 and Szabo et al, Nature 468, 521-526).

EuroStemCell aims to make this sort of cutting-edge scientific progress accessible to non-specialists, and to encourage discussion amongst the whole community. Thomas Graf has just written a short article on iPS versus transdifferentiation for eurostemcell.org. You can read the article at http://www.eurostemcell.org/commentary .

We’d love it if Node readers posted their opinions on the value and future of these two techniques as comments on the article. Just sign up to the site (a VERY simple, 2-minute process) and then go to Thomas Graf’s article and click ‘add a new comment’.

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The EMBO Meeting 2011 – Abstract submission and registration now open

Posted by , on 1 March 2011

10 – 13 September 2011, Vienna, Austria

Featuring more than 120 world-class scientific speakers, including: Richard Axel, Susan Lindquist, Eric Wieschaus and Giacomo Rizzolatti.

Three plenary lecture sessions: microbiology of infection, genome evolution and neuroscience.

21 concurrent sessions juxtaposing classical fields of research with those exploring new frontiers in molecular biology.

Daily poster sessions, career skills development workshops and much more.

EARLY REGISTRATION: 15 MAY 2011
ABSTRACT SUBMISSION: 22 MAY 2011

To see the whole programme, to submit abstracts and to register visit: www.the-embo-meeting.org

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Postdoctoral position in Regenerative Biology in Xenopus

Posted by , on 1 March 2011

Closing Date: 15 March 2021

A postdoctoral position is available in the Laboratory of Dr. Juan Larraín, at the Pontificia Universidad Católica de Chile, Santiago, Chile. The project involves the study of regenerative biology in Xenopus, and is developed under the Millenium Nucleus in Regeneratibe Biology (MINREB) and the Center for Aging and Regeneration (CARE). The Faculty is located at the center of Santiago, the capital city of Chile.

Applicants should have experience in Molecular Biology. The start date can be negotiated.

People interested can contact Dr. Juan Larraín at jlarrain@bio.puc.cl. Please include CV, publications and two (2) references. Applications are welcomed until April, 30.

More information can be obtained at www.minreb.cl and www.carechile.cl/home.php.

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Select a Development cover image from the Woods Hole course

Posted by , on 28 February 2011

Last summer you’ve been able to follow the experiences of a few of the students of the Woods Hole embryology course on the Node. You could tell from their stories that they learned different imaging techniques and studied a range of unique organisms.

The images produced in this course deserve a much wider audience, so Development has reserved some covers for images from the Woods Hole embryology course. The problem: there were far too many great images! We’ve made a selection, together with course co-director Nipam Patel, to narrow it down to the images that pass all the technical requirements for a cover, and now it’s down to you, the readers of the Node, to choose which ones you’d like to see as a journal cover.

There are four batches of images, so we’ll ask again a few more times, but here is the first group. Which of these images would you like to see on the cover of Development? Please vote in the poll below the images. (Click any image to see a larger version.) You can vote until March 8, 12:00 (noon) GMT

1. Mouth of an adult sea urchin feeding on a fragment of seaweed. This image was taken by Sarah A. Elliott (University of Utah) and Nobuo Ueda (University of Queensland).

2. Germband extended stage Drosophila embryo.  Confocal image (extended focus) showing the expression of Engrailed (orange) and Vasa (green).  Dividing cells are highlighted in pink (PhosphoH3), and remaining nuclei are blue (DAPI). This image was taken by James Tarver (University of Bristol).

3. Zebrafish embryo with cells of the gut highlighted in purple. This image was taken by Ann Grosse (University of Michigan).

4. Squid embryo visualized by a combination of brightfield and fluorescence imaging (DAPI in blue and phalloidin in red). This image was taken by Jennifer Hohagen (Georg-August-University of Goettingen).


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Image contest deadline extended (and other image news)

Posted by , on 25 February 2011

Good news if you were rushing to get your images in in time for our image competition: we’ve extended the deadline to March 15. We’ve seen all sorts of unique interpretations of the theme “intersections” as applied to developmental biology among the submissions so far. Make sure to send yours in, too – you just got an extra two weeks for that!

Remember, the winner gets to choose their own work of TipArt. TipArt made use this lovely Node logo (you can see it in progress here), but they can do (almost) anything!

However, even though the contest voting round is pushed back a bit, we do have image voting coming up next week. Not for the Node’s image competition, but for a cover for Development. Students of the 2010 Woods Hole Embryology course have taken some beautiful photos in the course of their weeks there (some of which you have seen on the Node before), and it’s up to you – the readers of the Node – to select which ones you would like to see as a cover on Development. There will be a few of these cover voting rounds, and the first one will be on the Node on Monday February 28.

And in final image news, the Wellcome Image Awards 2011 were announced this week, and include many developmental biology images: Cell division in plants, mouse embryo visualisation, fish eye development, blastocysts, a developing mouse kidney, chromatin density in chromosomes, caterpillar prolegs – about half of the images in this year’s batch are related to developmental biology! We might hear a bit more from some of the winners soon.

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BSCB-BSDB Meeting 2011 – Early Bird Deadline Approaching

Posted by , on 24 February 2011

Don’t miss the early bird registration deadline for this year’s BSCB-BSDB meeting. To receive the discounted price make sure you’re registered by Friday 4th March.

The conference is the annual main meeting of the British Societies for Cell and Developmental Biology. This year it will be at Kent University in Canterbury from 27-30 April 2011. There’s a great line up of invited speakers, workshops and posters, along side the regular prize lectures and social events.

All the details at: www.bscb-bsdb-meetings.co.uk

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Primitive Streak – a fashion exhibit and website

Posted by , on 23 February 2011

In 1997, sisters Helen and Kate Storey collaborated on a project spanning their respective areas of expertise: fashion design and developmental biology.

The result was a highly acclaimed collection of dresses, designed by Helen Storey, that each represent a stage in early development. Recently, the Wellcome Trust renewed funding for the work, and Primitive Streak is once again on display. With the new tour, which started in Sheffield (UK) earlier this week, comes a brand new website as well.

Kate Storey, the scientist of the two sisters (and not unfamiliar to Node readers), has been involved with putting each dress in scientific context. The website features videos and images of the developmental processes corresponding to the pieces, so that you can compare exactly how much the Neurulation Dress really looks like a neural plate folding into the neural tube – somites included!

Photography © John Ross. Model: Connie Chiu. Image used with permission

For each step in the developmental process (and hence, each design) the site also provides a list of labs that are working on that particular stage of development, and an explanation of what happens when development goes wrong: The page for the Limb Formation Dress, for example, has a section on thalidomide, and links to the labs of Cheryll Tickle, Cliff Tabin, and Neil Vargison.

By putting each work in chronological order (starting with the 1000 Sperm Coat) and giving detailed information, the scientific section of the website provides a new perspective on the dresses for people unfamiliar with developmental biology. At the same time, it’s an introduction to fashion for an audience interested in biology: there is an obvious rationale behind the designs, and the scientific explanation and images really bring that home.

If you’re curious about the collaboration between Kate and Helen, the website’s introduction links to the diary they kept in 1997. Here are a few snippets:

“We talked and drew developing embryos for three hours. I tried to describe why these events were important. It was exhausting. Too much to take in for Helen. Hard for me to translate everything into layman’s terms.” – Kate’s diary April 28, 1997

“Kate came down to look at the collection’s progress. She seemed interested in my work environment, and in a joint interview made her first-ever verbal observation of my little world. She seemed pleasantly surprised at the similarities between how a lab is run and a workroom.” – Helen’s diary, August 12, 1997

Most of the pieces in Primitive Streak were designed when the project first launched in 1997, but thanks to an additional batch of funding received this year, a brand new Lung Formation Dress has joined the set. This dress represents various stages of lung development, from embryonic day 26 to fully-formed adult lungs. All dresses are currently on display in Sheffield’s Winter Garden, but if you’re not able to make it there, the website is a very good alternative.

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Postdoctoral Scholar position in pancreas development

Posted by , on 22 February 2011

Closing Date: 15 March 2021

A postdoctoral scholar position is currently available in the Lynn Lab, located at the University of British Columbia in beautiful Vancouver Canada, for a qualified individual interested in studying the regulation of pancreatic beta cell development. The project will use mouse and human systems to address how microRNAs regulate pancreatic progenitors and pancreatic beta cell differentiation.
The ideal applicant will possess doctorate in cell, developmental or stem cell biology; and a curiosity and passion for science.  You must also have a talent for independent research, which is supported by a strong publication record.
Please send by e-mail (francis at lynnlab dot com): a cover letter highlighting your past research accomplishments, future research interests and please outline why you would like to join our group. Please include your vita and copies of your highest impact publications (2 maximum).  Please mention you saw this ad on The Node.

web: http://www.betacell.ca

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