Soon after starting the first year of medical school, I had ambitions of undertaking substantial scientific research in future since biomedical research and clinical practice complement each other, but little idea about the nature of scientific research. On my search for a project, I came across the Gallop lab at the Gurdon Institute and was able to attend an interview with the lab where I presented a paper. I was then provisionally accepted as a summer student, and after a successful application for a BSDB Studentship, the project was given the go ahead.

The Gallop lab investigates actin signalling with emphasis on filopodia, regarding their macroscopic behaviour, molecular dynamics, and lipid composition. Actin biology had been mentioned in our first year courses but not explored further. I was therefore eager to research a relatively novel area for myself, and after discussion with Dr Gallop we decided on a project which would cater to both the labs and my interests.

The project would use embryos from the African clawed frog, Xenopus laevis, to study filopodia. The lab had recently discovered heterogeneity of actin regulatory molecules at filopodial tips, noting that filopodial extension and retraction rates in Drosophila myotubes forming myotendinous junctions follow a defined mathematical relationship, the Laplace distribution (Dobramysl et al. (2021)).

The distribution highlights how the poorly understood and apparently random biochemical processes in filopodia are still governed by some underlying order. The theoretical framework for our current understanding of filopodia dynamics, is that actin polymerisation is happens at the tips, with constant retrograde flow and actin depolymerisation occurring at the filopodium base (Mallavarapu and Mitchison, 1999). Therefore, a question my project sought to answer was whether other filopodia and actin incorporation at the tips also follow Laplace distributions in their dynamics. To answer this, I used leading edge mesendoderm (LEM) cells, isolated from stage 10.25 Xenopus gastrula and allowed to spread on a fibronectin matrix because of their accessibility and short incubation time. Additionally, the large cells at the 2-cell stage allow ease of injecting labelled membrane marker RNA (GAP-RFP) and labelled actin (with Atto-488). Any differences between the macroscopic behaviour of filopodia in cells in vivo compared ex vivo could provide insight into factors driving the filopodia behaviour.

If filopodia extension/retraction rates in Xenopus LEM cells fit a Laplace distribution, a further research question would be whether actin depolymerisation solely occurs at the filopodia base or if there may be actin depolymerisation at the filopodia tips too. Any findings can account for variations in the rates of filopodia extension and retraction.

TIRF (Total Internal Reflection Fluorescence) microscopy would be used to image filopodia. The membrane marker allows visualisation of the filopodia outline, and timelapses can then be analysed to track many filopodia over time using a plugin called ‘Filopodyan’ written in Fiji and R (Urbancic et al, 2017), producing graphs showing the distribution of filopodia extension and retraction rates. The labelled actin allows for photobleaching to answer the second research question, by tracking a stripe of photobleached actin.

The start of the project mostly involved learning techniques. I learned how to fertilise, treat, and inject embryos, take explants, and use the microscope. Because of the intricate nature of injecting embryos and taking explants, developing these skills were enjoyable but took time. I found explant-taking with eyebrow knives and hair-loops especially fun, reinforcing my desire to choose hands-on surgical specialties in future. Towards the end of the project, I was pleased to see the improvement in my aptitude for injecting embryos and taking explants.

The first experiment was in week 2, but it was found that the explants were not targeted enough, and a lot of vegetal endoderm persisted in the MaTek dishes used for imaging. There was also no actin fluorescence, so we hypothesised injecting GAP-RFP and labelled actin in separate needles, rather than a single, might allow actin to be introduced successfully. The second experiment was indeed more successful, as LEM cells with filopodia could be seen with some examples in Fig. 1 below.

Fig. 1 – LEM cell with good filopodia, especially in the enlarged frame. Actin signal was weaker than membrane marker signal.

Further experiments focused on improving the actin signal intensity for more accurate filopodia segmentation in ImageJ. We tried switching wavelengths to use actin conjugated with a red dye (Alexa-568) and increasing the Atto-488 actin concentration, the latter of which proved more successful. Getting accurate and precise explants was also difficult, however refining the explant technique with help from Dr Gallop and my day-to-day supervisor, Julia Mason, improved the yield of LEM cells.

LEM cells had many mobile filopodia on the leading edge, however aside from segmentation problems due to low actin signal, overlapping filopodia were also inaccurately segmented by Filopodyan. A few cells from the final runs could be analysed fully in ImageJ, generating tables which were fed into the Filopodyan script in R and producing graphs that approximated a Laplace distribution of filopodia extension and retraction rates.

Finally, to address the project specifically, the script had to be rewritten to plot a logarithmic scatter plot instead of a histogram. The best fit lines still need integrating into the script, and this along with perfecting the experimental procedure could form the basis for another short project to finish my work on the Laplace distribution and answer the second part of the research question on actin dynamics.

Overall the project has been invaluable, not only in developing hard skills like working with basic bench equipment, manipulating embryos and imaging, but also in highlighting the unpredictable nature of scientific research. Completing this project has better prepared me for future research opportunities, which I will be seeking, as well as allowed me to meet excellent colleagues which have been of great help, for which I express my deepest gratitude.

References:

Dobramysl U, Jarsch IK, Inoue Y, Shimo H, Richier B, Gadsby JR, Mason J, Szałapak A, Ioannou PS, Correia GP, Walrant A, Butler R, Hannezo E, Simons BD, Gallop JL. Stochastic combinations of actin regulatory proteins are sufficient to drive filopodia formation. J Cell Biol. 2021 Apr 5;220(4):e202003052.
Mallavarapu A, Mitchison T. Regulated actin cytoskeleton assembly at filopodium tips controls their extension and retraction. J Cell Biol. 1999 Sep 6;146(5):1097-106.
Urbančič V, Butler R, Richier B, Peter M, Mason J, Livesey FJ, Holt CE, Gallop JL. Filopodyan: An open-source pipeline for the analysis of filopodia. J Cell Biol. 2017 Oct 2;216(10):3405-3422.

(7 votes)

Loading...

São Paulo School of Advanced Science in Stem Cell Biology Sept 16-24 Ribeirão Preto, Brazil
With the FAPESP / May Rubião SPSAS on Stem Cell Biology, we intend to make a qualitative leap in bringing together national and international scientists to promote stem cell research among graduate students and young researchers. The goal of this program is to encourage more interest in and research on stem cells and closing the gap between fundamental and applied research focused on stem cell therapy and tissue bioengineering.

The partnership that we established with the International Society for Stem Cell Research (ISSCR) to carry out the SPSAS on Stem Cell Biology and the course-ending international symposium will encourage more interest in and research on stem cells so that the participants can continue to play a significant global role in advancing this field.

Undergraduate, graduate students, and post-doctoral fellows from all countries are encouraged to apply.

The Selection Committee will select 100 participants (50 from all states of Brazil and 50 international) to be fully funded by the FAPESP SPSAS Program. Funding includes travel, travel insurance (for international participants only), accommodation, and meals throughout the event.
Application deadlines and selection criteria:
https://www.sbbc.org.br/spsas-stemcellbiology/application/

(No Ratings Yet)

Loading...

Doing great science depends on teamwork, whether this is within the lab or in collaboration with other labs. However, sometimes the resources that support our work can be overlooked. Our ‘Featured resource’ series aims to shine a light on these unsung heroes of the science world. In our latest article, we hear from Cheryl Telmer, who describes the work of Echinobase.

Overview

Echinobase (www.echinobase.org) is a model organism knowledgebase for the echinoderm research community (Arshinoff et al. 2022). The Phylum Echinodermata has 5 Classes: the basal branching Crinoidea (crinoids), and the 4 motile Eleutherozoa Classes including Asterozoa, composed of the Ophiuroidea (brittle stars) and Asteroidea (starfish) and the Echinozoa, composed of the Echinoidea (sea urchins and sand dollars) and Holothuroidea (sea cucumbers). Echinoderms, along with the phyla Chordata and Hemichordata are Deuterostomes.  The species used in research labs have many advantages for studying embryo development and regeneration including an abundance of gametes, synchronized fertilization, transparent embryos and larvae, ease of microinjection and micromanipulation, and variation in development within and between a species. This has made echinoderms a premier model system to study gene regulation, genomic control of cell specification and gene regulatory networks in development and evolution. 

Echinobase is the third generation computational resource for the support of all genomic data and research using echinoderm model organisms.

The Echinobase Teams

Echinobase has been developed from previous databases including SpBase (previously funded by NIH R01 to PI Andy Cameron, 2007-2012) and EchinoBase (NIH P41 to PI Cameron, 2012-2018). Echinobase development is now funded through a collaborative NIH P41 between Carnegie Mellon University (PIs Hinman/Ettensohn) and the University of Calgary (PI Vize). The database and software development team are in Calgary and also run the Xenopus knowledgebase, Xenbase. The data curation and bioinformatics team are at Carnegie Mellon University, where the PIs are leading researchers in the echinoderm research community. The current Echinobase is a clone of Xenbase which has adapted multiple new features and content in support of the echinoderm community, and broader needs of the developmental biology communities. 

Support for Genomics Research

The most current genome assemblies are hosted on Echinobase. Currently four species are fully supported, Strongylocentrotus purpuratus (purple sea urchin), Lytechinus variegatus (variegated sea urchin), Patiria miniata (bat star) and Acanthaster planci (Crown of Thorns sea star). Partial support (BLAST and JBrowse) is provided for Asterias rubens (sugar star) and Anneissia japonica (feather star, a crinoid). Search and BLAST tools are available on the landing page or through the over 38,000 gene pages. Gene pages also display gene model HGNC compliant names, multispecies orthology, GO terms, a link to the JBrowse genome browser, and a gene expression plotting tool. Tabs beyond the summary on the gene page provide gene specific literature, transcripts, expression data, protein sequences, interactants and more. 

The Echinoderm Anatomical Ontology

The Echinoderm Anatomical Ontology (ECAO) describes echinoderm anatomy and embryological development using a controlled vocabulary of anatomy terms and developmental stages that are organized in a hierarchy with a graphical structure. Echinobase curators use ECAO terms to describe the spatiotemporal expression patterns of endogenous gene products, the transcriptional activity of cis-regulatory modules, the effects of morpholinos, and other types of biological information. The ECAO is constantly being updated in response to the latest published echinoderm research.

The ECAO contains 1000’s of terms and relationships. Each anatomical system (e.g. nervous system, skeletal system), tissue and structure (e.g. ciliary band, mesoderm, blastopore) and many cell types (e.g. pigment cell, serotonergic neuron, skeletogenic mesenchyme cell) are separate terms; each term is fully defined and related to other terms by is_a, part_of, develops_from and develops_into relationships. The ontology makes text and data computer readable and allows our code to link and infer relationships between many different types of content.

Manual and Automated Curation

Automated literature collection has retrieved over 18,000 publications for automated and manual curation. Text matching automatically links gene symbols or names appearing in manuscript text to gene pages. Manual curation extracts sequence information for morpholinos, gRNAs, and cis-regulatory elements and itemizes antibodies used in experiments.  

Sharing on EchinoWiki and FTP

To support the community, collections of data, protocols and other resources are shared using EchinoWiki and an FTP site. To enable interdisciplinary and collaborative studies, contact information for community members and groups and information about their research are available and searchable.

Help from users

The echinoderm research community has always been extremely supportive and can continue to do so at many levels. It is highly important and appreciated if users cite Echinobase whenever possible in articles, presentations and funding applications (citation link in the top right corner of the webpage “Citing Echinobase”). These acknowledgements make Echinobase’s impact on research more tangible and specifically the article citations provide metrics that can be used for funding applications.

Help from authors 

Authors can also contribute in several ways to simplify the curation of their articles, ultimately allowing their data to be more quickly available on the website. 

When you write your paper…

In addition to “Citing Echinobase”, clear, detailed and accurate descriptions of the experiments and resources minimizes the curation effort and reduces the need to contact the authors. Articles should mention official Echinobase identifiers and nomenclature for entities such as genes, alleles, and anatomical structures. 

Bibliography

Arshinoff BI, Cary GA, Karimi K, Foley S, Agalakov S, Delgado F, Lotay VS, Ku CJ, Pells TJ, Beatman TR, Kim E, Cameron RA, Vize PD, Telmer CA, Croce J, Ettensohn CA, Hinman VF, Echinobase: leveraging an extant model organism database to build a knowledgebase supporting research on the genomics and biology of echinoderms, Nucleic Acids Research, Volume 50, Issue D1, 10.1093/nar/gkab1005

(1 votes)

Loading...

We loved Ewan St. John Smith’s tweet about the Chronophage clock that can be found in our home city, Cambridge. With Ewan’s permission, we have reproduced most of the thread celebrating the birthday of the clock’s inventor, Dr John C Taylor OBE, but you can also find the tweetorial on Twitter.

Today (25 November) marks a special day in the annual rhythm of the Corpus Chronophage Clock.

I (Ewan St. John Smith) am a Fellow in Pharmacology at Corpus Christi College, Cambridge, teaching medicine & biology, but I am also the Custodian of the Corpus Chronophage Clock. One of my jobs is to give tours of the Clock on College feast day but, today there is a need for a virtual tour.

The Clock sits on what used to be the entrance to a Natwest Bank, a building built in 1866 (architect Horace Francis) that originally housed the London County Bank. Natwest’s lease ended in 2005. The College needed better library provision for students. The then library was situated under the Parker Library and moving students out meant better facilities for students/researchers to access the Parker. However, the old entrance to Natwest couldn’t just be bricked up due to planning restrictions. What to do? That’s where inventor & alumnus Dr John C Taylor OBE comes in. Inventor of the bimetallic thermostat control present in electric kettles (http://johnctaylor.com), John is also an horologist & designed the Corpus Chronophage Clock that was built by Huxley Bertram.

But this is no ordinary clock. The escapement wheel is made from a single sheet of steel, plated in gold, created by a series of explosions in a vacuum, the radiating ripples that this has created allude to the Big Bang & the clock was inaugurated in 2008 by Stephen Hawking. Atop the wheel sits the Chronophage (time eater). It is an example of the grasshopper escapement mechanism invented by John Harrison in the 1700s. The Chronophage’s mouth opens at 30 sec past each minute, snapping shut when the minute is over: time passes & we all die.

When the hour is struck, there is no chiming of bells, but rather the rustling of chains & a hammer strikes a wooden coffin to sound out the passing of another hour – perhaps a little off putting for those studying in the library behind the clock! To tell the time, there are 3 LED wheels (2736 LEDs) to show seconds, minutes & hours, but this clock can play tricks…

Because our perception of time is always altered by what is going on & the clock’s trickery adds to that. In this video the clock is behaving…

But here the clock is playing tricks, watch the pendulum in this video! The clock has 50 tricks, a special set is reserved for 4 special days: John Harrison’s birthday (March 24th), John Taylor’s birthday (Nov. 25th – today 🥳), New Year’s Day & Corpus Christi Day.

When playing these tricks, the clock gets a little out of time, but have no fear, it can run 10% fast & 90% slow, thus enabling a rapid realignment. This ability also enables the clock to cope with the clocks going forwards/backwards. (For fun, here are more tricks!)

The pendulum has an inscription. Joh = Johannes = John; Sarto = Taylor, Monan = Monanensis = Isle of Man, Inv. = Invenit = to create, MMVIII = 2008: John Taylor from the Isle of Man made this in 2008. There are 10 peaks on the rhodium dish at the bottom that can be pointed at by the pendulum when playing certain tricks, a further homage to John Harrison and the accuracy achieved with his clocks centuries ago!

And of course, like all good clocks, there is a key, but this one is purely ceremonial. When spun, the key tells you to which clock it belongs & top left is the image of the bimetallic thermostat for the kettle!

The Chronophage has proved inspirational, perhaps most recently in research from Andrea Brand’s lab where they identified a temporal transcription factor in Drosophila that they named Chronophage in view of its role in regulating neurogenesis

Drosophila homologue of CTIP1 (Bcl11a) and CTIP2 (Bcl11b) regulates neural stem cell temporal patterning

So, that’s a little overview of what is truly an incredible thing, slap bang in the middle of Cambridge for everyone to see with plenty more secrets to share, all of which are courtesy of the man whose birthday it is today, Dr John C Taylor OBE.

– happy birthday John!

(No Ratings Yet)

Loading...

We developed a Shiny App to explore our latest scRNAseq dataset of the E12.5 mouse hem and choroid plexus. You can access it here. It comes as a complement to our previous App focusing on the ventral, lateral and dorsal pallium.

Check the full story on bioRxiv:

https://www.biorxiv.org/content/10.1101/2022.11.18.517020v1

(No Ratings Yet)

Loading...

The September issue of our journal Disease Models & Mechanisms (DMM) has a focus on how researchers can best leverage model organisms to improve our understanding of human health and disease. Here, we highlight some of the articles and encourage you to visit the journal website, where all the articles are available to read Open Access.

The issue includes a Special Article by Keith Cheng, Hugo Bellen and colleagues on the importance of promoting validation and cross-phylogenetic integration in model organism research. The article draws on a discussion series organised by the National Institutes of Health (NIH) to gather opinions on how researchers can further extend the utility of model organisms in the future. The authors discuss some of the key ideas identified by the NIH discussions, including:

• Developing new tools and technologies.
  Ideas include humanising model organisms to better model human diseases, generating reference atlases to allow comparison between model organism and human data, and developing new reagents such as species-specific antibodies.
• Broadening the range of model organism species used in research.
  Different species offer specific advantages for modelling human disease. For example, hamsters share similar lung physiology to humans so have proved useful in COVID-19 studies. Expanding the range of species used in disease research could therefore offer researchers greater access to useful models that have been previously overlooked or underused.
• Increasing genetic variation.
  Laboratory animal strains are often inbred to reduce variation. However, humans have a great deal of genetic diversity, so it will be important to use a suite of diverse models to better reflect the variation in human disease.
• Integration between different disciplines and organisms.
  It will be important to integrate phenotypic data from different disciplines (such as biochemistry, cell biology, genomics and behavioural studies) as well as data from studies in different model organism species. This will help to form a more complete picture of the disease phenotype.

An example of a new initiative that aims to improve integration across disciplines is the UK Medical Research Council (MRC) National Mouse Genetics Network. You can read more about this in Owen Sansom’s Editorial. Owen explains that the Network will comprise seven research clusters, each focusing on different yet complementary research areas. The aim is to share data, techniques and resources, and to encourage collaboration within the mouse model community.

The September issue of DMM also contains a study from Muneer Hasham and colleagues at the Jackson Laboratory (JAX), USA, which expands the genetic diversity of mouse models available for xenografting experiments. Xenografting human cancer cells in mice is a well-established method for studying tumour development and testing potential therapeutic drugs. These mice must lack B- and T-lymphocytes for xenografting to be successful, and researchers can achieve this by generating mouse strains that are Rag1 deficient. However, the genetic diversity of available Rag1-/- mouse strains is limited.

In their paper, the JAX group generate five genetically diverse Rag1-/- mouse strains. Together, these strains cover 90% of the known allelic diversity in the mouse genome. They show that the genetic background of the host strain plays an important role in the outcome of the xenograft; for example, they find that tumour size varies between the five different host strains. This article was also highlighted as the DMM Editor’s Choice.

You can read a response to the work by Dr Hasham and colleagues in the same issue of DMM, where Ryan Devlin and Ed Roberts tackle the question of how researchers can build a healthy mouse model system to better interrogate cancer biology. Taking the JAX lab paper as a case study, they suggest implementing a ‘Swiss cheese model’ to design better experiments. This model is already used in accident prevention strategies, where the concept of layering multiple strategies (each with their own weaknesses, as represented by holes in the slice of cheese) is employed to reduce the chance of an accident.

In a similar vein, Ryan and Ed suggest that researchers can layer a suite of different mouse models, rather than trying to identify the ‘best’ model. This is because each model has its own weaknesses so, by combining models that complement one another, scientists can reduce the chances of a harmful or ineffective chemotherapeutic drug reaching the clinical trial stage.

Finally, researchers from JAX have also provided a Perspective for the October issue of DMM. In the article, Karen Svenson and colleagues respond to the NIH’s 2021 recommendations to improve the reproducibility of animal studies. They share their own experiences of addressing this issue, with a specific focus on mouse models.

Want to keep up with the latest news from DMM? Visit the DMM website and follow the journal on Twitter and/or Mastodon to find out more.

(No Ratings Yet)

Loading...

“We’re testing the air for tigers and digging up dead bodies as we explore the exciting new field of environmental DNA”

Dr Sally Le Page

In the latest episode of the Genetics Unzipped podcast, we’re testing the air for tigers and digging up dead bodies as we explore the exciting new field of environmental DNA. Dr Sally Le Page chats with Prof. Elizabeth Clare about sampling the DNA of rare species from the air, and Dr Kirstin Meyer-Kaiser and Charles Konsitzke tells us about their project using eDNA to recover the missing bodies of fallen service personnel.

Genetics Unzipped is the podcast from The Genetics Society. Full transcript, links and references available online at GeneticsUnzipped.com.

Subscribe from Apple podcasts, Spotify, or wherever you get your podcasts.

Head over to GeneticsUnzipped.com to catch up on our extensive back catalogue.If you enjoy the show, please do rate and review on Apple podcasts and help to spread the word on social media. And you can always send feedback and suggestions for future episodes and guests to podcast@geneticsunzipped.com Follow us on Twitter – @geneticsunzip

(No Ratings Yet)

Loading...

By Zoe Mann, Ahmed Mahmoud, Ana Rita Diogo Robelo and Neha Agrawal

Hidden away in the beautiful countryside, a group of scientists gathered at Buxted Park to brainstorm the roles of metabolism in the developmental origins of health and disease (DOHaD). In this peaceful setting, early career researchers (ECRs) had the opportunity to network and exchange ideas with leaders in their respective fields. Being one of the first in-person workshops since the pandemic, energy levels and excitement were high.

The program, which was well organized by Alex Gould and Sally Dunwoodie, was filled with interdisciplinary presentations and stimulating, fruitful discussions between scientists, which continued throughout the day over lunch, coffee breaks, long leisurely walks and well into the evening over dinner and drinks. The venue and small size of the Workshop promoted engagement between participants in a way that is not possible at larger scientific meetings. Also, attendees were encouraged to present unpublished data, which prompted useful and interesting discussions about the most recent advances in DOHaD. For the majority, this workshop bore new collaborations, ideas and friendships.

Throughout the week, we listened to outstanding talks exploring the role of developmental metabolism in worms, flies, xenopus, birds, mice and humans. The interdisciplinary nature of this Workshop revealed that regardless of the model system and field of study pursued by the participating scientists, a common theme remained consistent, which is the importance of the DOHaD in their respective fields. Furthermore, it was fascinating and refreshing to hear many works that bridge together transcriptomics, proteomics and metabolomics for a comprehensive understanding of how genetics, nutrition and environment can modulate metabolism and, consequently, development. For example, metabolic disruptions in the placenta can have a defining role in disease manifestation in multiple organs later in life. Similarly, early exposure to hypoxia during development can have lasting detrimental metabolic effects on offspring. Understanding these processes is therefore informative not only for developmental biology, but also for informing clinical research and public health policy.

A ‘hot topics’ discussion on the penultimate day was helpful in identifying important ideas and focus areas for further development in this field. The role of cutting-edge technologies, such as spatial metabolomics and assessing metabolomes at single cell resolution, was highlighted. In particular, the need to communicate the importance of DOHaD in both research and clinical settings was strongly emphasized throughout the meeting. Indeed, broadening our view will allow the scientific community to acknowledge that, not only the genetic background, but also the metabolic state of an organism, can be associated with and even drive developmental defects or tumorigenesis. Additionally, a major conclusion from the Workshop was the need to advocate for increased awareness of DOHaD, even amongst developmental biologists.

In this focused setting, the friendly environment and small community inspired new interdisciplinary research aimed at uncovering the mechanistic links between early-life metabolism and adult health and disease. Should the chance to take part in one of these Company of Biologists Workshops arise, do not hesitate to apply. You will hear about cutting-edge research, build new and inspiring collaborations, network with leaders in the field and, above all, have fun.

(2 votes)

Loading...

In the past couple of weeks, #ScienceTwitter was full of tweets starting with ‘If Twitter ends today, can we all agree that…’, professing their love for a particular model organism, and whether qPCR is essential for validation! Of course, Twitter hasn’t collapsed but the #devbio community, including ourselves, have been trying Mastodon as an alternative. Read on to find out some of the talking points that caught our attention.

To move or not to move?

Publishing on Mastodon

Who’s (who) on Mastodon

We’re at @the_node@mstdn.science, and we’re still building our community on Mastodon, but below are some of our favourites so far. Let us know who we should be adding to our list!

• @cellysally@mas.to
• @JoachimGoedhart@mas.to
• @mads100tist@mastodon.social
• @lab_ogden@mstdn.science
• @RogersLabUCD@mas.to
• @Odedrechavi@universeodon.com
• @ZebrafishRock@mstdn.social
• @richardsever@mas.to

Don’t forget the other Mastodon!

preLights in #devbio (and related topics)

To be or not to be a photoreceptor: cell fate choices in the developing zebrafish retina are deterministic and probabilistic.

How does the endothelium integrate mechanical force exerted by blood flow? Batta and colleagues show the importance for the guanine nucleotide exchange factor, ARHGEF18, in regulating endothelial cell alignment in the direction of flow.

Navigating a tense situation: the plasma membrane and actin cortex form an integrated system for rapid long-range tension propagation.

(No Ratings Yet)

Loading...

Investigating the rules of cell-to-cell interaction during pre-somitic mesoderm elongation

I discovered the field of developmental biology through independent reading during the first year of my undergraduate biomedical sciences program. I was fascinated by the process through which embryos develop, and the more I learned, the more questions I had. As Lewis Wolpert said, “Understanding the process of development in no way removes that sense of wonder”. I knew I wanted to gain some experience in working with embryos and I had the amazing opportunity to work in Ben Steventon’s lab at the Department of Genetics, University of Cambridge.

During development, cells interact with one another to generate collective migration. For example, cranial neural crest cells counterbalance contact inhibition of locomotion and coattraction to migrate through the embryo (Carmona-Fontaine et al., 2009; Carmona-Fontaine et al., 2011). The interactions between the cells of the pre-somitic mesoderm during vertebrate elongation are not understood as well. I focused on investigating the behaviour of the medial somite progenitor (MSP) population, using chick embryos as a model system.

I started by taking stage HH4 chick embryos out of eggs and placing them in PBS. Using a small syringe needle I then explanted the MSP region, which is located in the anterior primitive streak just below Hensen’s node. I transferred each explant on a dish coated with fibronectin and I imaged them every 10 minutes for 20 hours. After watching how the cells migrate in the dish (figure 1, movie 1), I wanted to find out how different explants would interact. I decided to culture two explants from the same region (anterior streak) next to each other, as well as an explant from the anterior region and an explant from the posterior region.

Surprisingly, in both situations, the cells did not mix. The anterior streak explants attracted each other in some cases (figure 2, movie 2), while the posterior streak explant seemed to be attracted by the anterior streak explant (figure 3, movie 3). There is no significant difference between the average timing of migration onset in anterior and posterior explants (figure 4A). To measure the rate of migration, I calculated the rate of change of diameter, and again there was no significant difference between the two populations (figure 4B). The attraction is not likely to be influenced by the distance, as there is no significant difference between the mean initial distance separating the explants in the cases where attraction occurs or does not. However, there seems to be a weak positive correlation between the initial size of the explant with the rate of migration. Explants with a larger initial diameter generally have a greater rate of change of diameter. This is true for both anterior explants (figure 4C) and posterior explants (figure 4D).  

I had an amazing experience working in the lab. Initially, I found it tricky to remove the embryos out of the egg and explant the region. I ended up breaking a few embryos and losing some explants. However, practicing the techniques every day helped me improve quickly. Each week I got more and more comfortable doing my experiments and my movies have significantly improved. The people in the lab were very friendly and always happy to help, so I had great support throughout my placement. I enjoyed the lab environment and the weeks passed by incredibly quickly. If I had more time, I would have liked to investigate the role of FGF signalling in the migration of these cells. I would have liked to inhibit FGF receptors to find whether the explants still attract or not, since streak cells are attracted by FGF4 and repelled by FGF8 (Yang et al., 2002). However, there seems to be more FGF8 and less FGF4 in the MSP region (Lawson et al., 2001; Shamim and Mason, 1999), so the fact that the explants attract seems to oppose this evidence.

I am interested in pursuing a PhD and my experience from this summer has only made me more determined.  I gained valuable insights into the reality of working in research. I had encountered some difficulties with my experiments and spent some time troubleshooting, however that did not put me off. Moreover, it made the results so much more rewarding, giving me a realistic view of what it is like to start a new project and how long experiments take. I appreciate the freedom I had in deciding which experiments to perform, how I would analyse the data, and the general structure of my day.  

I think everybody who is curious about research should apply for a BSDB summer studentship. There is nothing like experiencing research first-hand. I would like to thank Ben for hosting me in his lab, Tim for encouraging me to apply for this scheme in the first place, and everybody in the lab for teaching me various skills and being patient with me.

References

Carmona-Fontaine, C., Matthews, H., Kuriyama, S., Moreno, M., Dunn, G., Parsons, M., Stern, C. and Mayor, R., 2008. Contact inhibition of locomotion in vivo controls neural crest directional migration. Nature, 456(7224), pp.957-961.

Carmona-Fontaine, C., Theveneau, E., Tzekou, A., Tada, M., Woods, M., Page, K., Parsons, M., Lambris, J. and Mayor, R., 2011. Complement Fragment C3a Controls Mutual Cell Attraction during Collective Cell Migration. Developmental Cell, 21(6), pp.1026- 1037.

Lawson, A., Colas, J. and Schoenwolf, G., 2001. Classification scheme for genes expressed during formation and progression of the avian primitive streak. The Anatomical Record, 262(2), pp.221-226.

Shamim, H. and Mason, I., 1999. Expression of Fgf4 during early development of the chick embryo. Mechanisms of Development, 85(1-2), pp.189-192.

Wolpert, L., 2008. The triumph of the embryo. Mineola, N.Y.: Dover Publications, p.199.

Yang, X., Dormann, D., Münsterberg, A. and Weijer, C., 2002. Cell Movement Patterns during Gastrulation in the Chick Are Controlled by Positive and Negative Chemotaxis Mediated by FGF4 and FGF8. Developmental Cell, 3(3), pp.425-437.

(5 votes)

Loading...