Metagenomics and Ribosome Profiling Smartly Explained

The science behind molecular biology is advancing fast and scientists are eager to create and share new content. But the more content is being created, the harder it is to reach the desired audience. Therefore, the scientific community has had to come up with new attractive formats to help spread valuable scientific content.

One format that is currently popular is explainer videos, which combine both, audio and visual elements to untangle a topic. It has been proved that when one sense is activated we keep part of the information, but with the activation of multiple senses we can process and store far more.

We have therefore created explainer videos as part of our e-learning series.

“It was a great experience working on this project for our virtual courses. We are very fortunate to have Daniel Krüger, a former PhD student creating the graphics for these videos. This immensely improved the communication between the scientific advisers and the graphic designer because they speak the same language,” said EMBL Training Lab Manager Yvonne Yeboah, who came up with the idea of creating the explainer videos and led their production.

The first explainer video we are introducing deals with metagenomics, the genomic analysis of microbes by direct extraction and cloning of DNA, that allows studying communities of organisms directly in their natural environment.

“Our metagenomics course encompasses many different in silico and experimental approaches to understand and gain insights into microbial communities. Therefore, we thought that the visualisation of a video would provide students with an attractive overview that helps to connect and integrate all the aspects covered in the course,” explained José Eduardo González-Pastor, who organised the EMBO Practical Course: Microbial Metagenomics: A 360° Approach and acted as scientific advisor for the videos.

The second explainer video deals with the topic of ribosome profiling, a method that allows researchers to quantitatively analyse translation genome-wide and with high resolution. The video gives a comprehensive overview on how this technique works, what ribosome protected fragments (RPFs) are and what information we can obtain from them.

“Ribosome profiling is still an emerging technology. Therefore, it is great to have a concise summary that explains the method to students. I will certainly use the video for lectures and on my website,” said Sebastian Leidel and Jan Medenbach, both organisers of the EMBO Practical Course: Measuring Translational Dynamics by Ribosome Profiling and scientific advisors for the video.

Visit EMBL’s YouTube channel to find more exciting scientific content.

 

 

 

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Best Poster Awards — Chromatin and Epigenetics

The 10th edition of the EMBL Conference: Chromatin and Epigentics took place virtually this year. We welcomed more than 800 participants, from which 3 were selected best poster award winners prior to the meeting and who gave a short talk on the last day of the conference. Get a glimpse of their research.

Sequence-dependent surface condensation of pioneer transcription factor on DNA

Sina Wittmann, Max Planck Institute for Molecular Cell Biology and Genetics, Germany
Presenter: Sina Wittmann, Max Planck Institute for Molecular Cell Biology and Genetics, Germany

Abstract: Biomolecular condensates are dense assemblies of proteins that are dynamic and provide distinct biochemical compartments without being surrounded by a membrane. Some, such as P granules and stress granules, behave as droplets, have many millions of molecules, and are well described by a classic phase separation picture. Others, such as transcriptional condensates are thought to form on surfaces such as DNA, are small and contain thousands of molecules. However, the correct physical description of small condensates on DNA surfaces is still under discussion. Here we investigate this question using the pioneer transcription factor Klf4. We show that Klf4 can phase separate on its own at concentrations that are above physiological, but that at lower concentrations, Klf4 only forms condensates on DNA. Analysis using optical tweezers shows that these Klf4 condensates form on DNA by a switch-like transition from a thin adsorbed layer to a thick condensed layer that is well described as a prewetting transition on a heterogeneous substrate. Condensate formation of Klf4 on DNA is thus a form of surface condensation mediated by and limited to the DNA surface. Furthermore, we are investigating how Klf4 condensation is regulated by the property of the surface such as through DNA methylation. We speculate that the prewetting transition orchestrated by pioneer transcription factors underlies the formation of transcriptional condensates in cells and provides robustness to transcription regulation.

View poster.

Single-cell profiling of histone post-translational modifications and transcription in mouse and zebrafish differentiation systems

Presenter: Kim de Luca,  Hubrecht Institute, The Netherlands
Presenter: Kim de Luca,  Hubrecht Institute, The Netherlands

Abstract: During organism development and cellular differentiation, gene expression is carefully regulated at many levels. To that end, various epigenetic mechanisms translate cell-intrinsic and -extrinsic cues into activation and repression of the relevant parts of the genome. One of the most studied and versatile forms of epigenetic regulation is the post-translational modification (PTM) of the histone proteins around which DNA is wrapped. Histone PTMs affect the surrounding DNA by forming a binding platform for a range of effector proteins, as well as by directly modulating the biophysical properties of the chromatin. Hence, histone PTMs play a crucial role in priming, establishing, and maintaining transcriptional output and cell state. Many techniques used to study histone PTMs require thousands to millions of cells, and consequently mask the heterogeneity inherent to complex biological systems. To understand the nuanced relationship between chromatin context and transcription, single-cell and multi-modal approaches are necessary. We have previously developed a method to simultaneously measure transcriptional output and DNA-protein contacts by single-cell sequencing (scDam&T). This multi-modal method is particularly suitable for studying systems containing many transient cellular states. Here, we apply scDam&T to measure chromatin modifications by expressing the E. coli DNA adenine methyltransferase (Dam) fused to a domain that specifically recognizes a histone PTM. First, we validate this approach in population and single-cell samples by comparing the resulting data to orthogonal state-of-the-art techniques. Next, using mouse embryoid bodies as an in vitro differentiation system, we apply our method to deconvolve the lineage-specific regulation of Polycomb chromatin. Finally, we study the role of H3K9me3-marked heterochromatin in the developing zebrafish embryo.

Poster not available due to unpublished data, however, you can watch a short talk presentation here.

 

Presenter: Moushumi Das, University of Bern, Switzerland
Presenter: Moushumi Das, University of Bern, Switzerland

Poster and abstract not available due to unpublished data.

 

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Lazy Fur upgrades virtual conference experience with live music

Meet Ira and Tom – a newly-wed couple from Heidelberg and band members of Lazy Fur – a music duo that have been performing live for participants of numerous virtual EMBL conferences and symposia.

Tom and Ira of Lazy Fur. Ira holding a mic, Tom playing the guitar
Tom and Ira of Lazy Fur

“It feels good that we can bring joy and help provide even a better conference experience with a little bit of live music.”

Who is Lazy Fur?

Tom is a Research Staff Scientist in Matthias Hentze’s and Wolfgang Huber’s labs at EMBL Heidelberg and Ira is an executive assistant in a real estate company.

Both of them grew up with music. Ira started singing when she was little and now also plays the piano and bass guitar.

“I used to play the keyboard but discovered my calling as a guitarist in my PostDoc time at EMBL.” Tom shares.

They bonded over their passion for music and started playing acoustic covers of pop and rock songs and singer/songwriter style music. Ira is inspired by Walk Off The Earth, a Canadian group of friends who do spectacular covers of pop songs. And Tom is generally fascinated by buskers in Dublin he met during his PhD.

Virtual concert setup

Virtual conferences are great for many things, but it is very hard to organise entertainment. Lazy Fur found a way to give a live music performance and interact with participants.

Tom had to put in quite some effort to get it right:

“The technical side was quite challenging at first, but now we are very happy that we can provide high-quality streams. We can interact with the viewers who appreciate the live aspect of our performance. ”

What is it like to perform for a virtual audience?

Onsite, you can easily tell which songs the audience likes and if they like the show. In front of a virtual audience, it is more difficult, because you can not see and hear them. Tom and Ira did find a way to interact with the audience.

“The audience can communicate with us either via the YouTube or conference platform chat displayed on the TV in front of us.” Tom says. 

Ira: “We are extremely happy about all the positive responses we got in the chat or comments people sent us after the show.”

Tom: “We have had heart-warming messages from participants about how they enjoyed it. They wrote that this was a very unique and uplifting experience that reminded them of past conferences at the EMBL Heidelberg site.”

And after Covid-19?

Tom: “Performing live is just an amazing experience. EMBL has a great appreciation for live music at their events and it is wonderful to connect with people on that level. So yes, definitely looking forward to that as well!”

Lazy Fur will be performing at the virtual EMBO Workshop: Predicting Evolution, 14 – 16 June 

Check out the website of Lazy Fur
Check the Lazy Fur YouTube channel

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Best Poster Awards – The Identity and Evolution of Cell Types

The second edition of the EMBO | EMBL Symposium: The Identity and Evolution of Cell Types brought together an increased number of researchers from this growing community. 315 scientists joined the virtual meeting and enjoyed four days of talks and poster presentations streamed live. A total of 72 posters were presented at the two live poster sessions out of which three were selected as the best posters by popular vote. Take a look at the winners and their work.

Molecular fingerprinting sea anemones and jellyfish: A transcriptomic approach to characterize Cnidarian cell types
image of Alison Cole
Alison Cole, University of Vienna, Austria

Presenter: Alison Cole, University of Vienna, Austria

Abstract

Animals typically consist of hundreds of different cell types, yet the evolutionary mechanisms underlying the emergence of new cell types are unclear. Cnidarians offer advantages to studies of metazoan cell type evolution, as they are the sister group to the Bilateria and yet comprise an extremely diverse set of lineages that exhibit variable life history strategies, life spans, regenerative properties, animal-defining cell types (ie. muscles and neurons), as well as clade-specific cell types (i.e. cnidocytes). Advances in single cell RNA sequencing have opened the frontiers for molecular profiling of cell types at a genome-wide scale. Application of these technologies for comparisons across species remains in its infancy, and is largely, but not exclusively, restricted to closely related species with well-defined orthologous gene sets. Here we present a large single cell dataset derived from the anthozoan polyp Nematostella vectensis (comprising both developmental and tissue-derived samples),the scyphozoan moon jelly (Aurelia aurita; comprising all life history stages as well as medusa tissue-derived samples), and the hydrozoan Clytia hemispherica (young medusa only). The same cell complement that is identifiable from species-specific genome-wide analyses is recoverable using only a set of 1:1:1 orthologous genes in all three species. Analyses of the reduced gene matrix combining all three species robustly identifies putatively homologous cell types amongst the neurosecretory derivatives, as well as cell populations with clear species-specific transcriptomic profiles. Interpretations of these data in the light of specific cell types will be discussedin order to demonstrate that the combination of unbiased single cell transcriptomes and gene-directed validations can permit the identification of novel and conserved cell types.

View Poster


Stylophora pistillata cell atlas illuminates stony coral symbiosis, calcification and immunity
Anamaria Elek, Centre for Genomic Regulation, Spain

Presenter: Anamaria Elek, Centre for Genomic Regulation, Spain

Abstract

Stony corals are colonial cnidarians that sustain the most biodiverse marine ecosystems on Earth: coral reefs. Life cycle of these animals involves a swimming larva that settles and metamorphoses into a sessile polyp, which in turn develops into the adult stage, depositing in the process a protein rich organic matrix and extracellular calcium carbonate crystals to form a stony skeleton. Despite their ecological importance, little is known about the cell types and molecular pathways that underpin the biology of reef-building corals. Using single-cell RNA sequencing, we have defined over 40 cell types across the three life stages of a stony coral Stylophora pistillata. Among others, we characterized previously unknown coral immune cells, endosymbiont alga-hosting cells, and calicoblasts responsible for calcium-carbonate skeleton formation in both settling polyp and the adult coral. Apart from these specialized coral cell types, we identified evolutionary conserved cell types by phylogenetic integration of our S. pistillata cell atlas with three other available cnidarian species. These evolutionary conservations include neuronal and gland cell types, cnidaria-specific cnidocytes, and others. Overall, this study reveals the molecular and cellular basis of stony coral biology, and addresses the evolution of cell type programs in three major cnidarian lineages separated by 500 million years of evolution.

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Gene family evolution underlies cell type diversification in the hypothalamus of teleosts*
Maxwell Shafer, Biozentrum, University of Basel, Switzerland

Presenter: Maxwell ShaferBiozentrum, University of Basel, Switzerland

Abstract

Hundreds of cell types form the vertebrate brain, but it is largely unknown how similar these cellular repertoires are between or within species, or how cell type diversity evolves. To examine cell type diversity across and within species, we performed single-cell RNA sequencing of ~130,000 hypothalamic cells from zebrafish (Danio rerio) and surface- and cave-morphs of Mexican tetra (Astyanax mexicanus). We found that over 75% of cell types were shared between zebrafish and Mexican tetra, which last shared a common ancestor over 150 million years ago. Orthologous cell types displayed differential paralogue expression that was generated by sub-functionalization after genome duplication. Expression of terminal effector genes, such as neuropeptides, was more conserved than the expression of their associated transcriptional regulators. Species-specific cell types were enriched for the expression of species-specific genes, and characterized by the neo-functionalization of members of recently expanded or contracted gene families. Within species comparisons revealed differences in immune repertoires and transcriptional changes in neuropeptidergic cell types associated with genomic differences between surface- and cave-morphs. The single-cell atlases presented here are a powerful resource to explore hypothalamic cell types, and reveal how gene family evolution and the neo- and sub-functionalization of paralogs contribute to cellular diversity.

View Poster

*https://doi.org/10.1101/2020.12.13.414557 


Working on your own conference poster? Then check out these 8 tips for preparing a digital poster that stands out from the crowd.

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Best Poster and Artwork Awards — VIZBI 2021: Visualizing Biological Data

The 11th international meeting on Visualizing Biological Data, best known as VIZBI, was held virtually this year. The conference was as exciting as always, filled with great discussions, an outstanding speaker line-up and of course amazing, beautiful visuals.

The participants had the chance to vote for their favourite scientific poster and artwork — a very tough choice as all of the works were truly amazing! Here, we present you the winners.

Best scientific poster

Building a whole cell in 3D

by  Martina Maritan (The Scripps Research Institute, USA) Ludovic Autin, Jonathan Karr, Markus Covert, Arthur Olson, David Goodsell.

Martina Maritan, The Scripps Research Institute, USA
Martina Maritan

Mesoscale 3D models are powerful tools for exploring structural data across the entire range of scales, from the molecular to the cellular level. We built structural mesoscale models of a whole Mycoplasma genitalium (MG) cell with the CellPACK suite using data generated from a whole-cell MG simulation. 3D models integrate structural details into a computational model of MG, highlighting specific properties of the ingredients, and creating snapshots of the cell at defined time points of the simulations. Our modeling process goes through three steps. Firstly, we assemble a recipe: a list of all the proteins of Mycoplasma associated with a structural representation. Secondly, we create a model of the genome with DNA, RNA, RNA polymerase, mRNA, and ribosomes, with user-defined location of RNA polymerase and length of transcripts. Thirdly, we assemble the nucleoid, soluble, and membrane ingredients, and relax the whole system to resolve steric overlaps. The result is a framework for interactive construction of atomic resolution mesoscale models describing a spatial view of a whole bacterial cell. Our models are the first atomistic representation of an entire bacterial cell.

Building a whole cell in 3D
Building a whole cell in 3D

View Martina Maritan’s poster
Watch lightning talk

Second best scientific poster

How to communicate cell behaviours visually

by Christian StolteCellarity, USA.

Christian Stolte, Cellarity, USA
Christian Stolte

Cellarity is pioneering a new approach to drug discovery, treating disease at the level of the cell as opposed to a single molecular target. Combining unique expertise in network biology, high-resolution single-cell sequencing data, and machine learning, the result is a new understanding of the cell’s trajectory from health to disease, and how cells relate to one another in tissues. The cell and its network of transcripts and proteins offer a more complete view of the complexity of human biology than any individual molecular target. To help communicate this, we use visualizations resembling a cityscape called ‘Cellarity maps’. Based on the UMAP dimensionality reduction technique, they use the third dimension (height) to show density. This creates landscapes where we can now use colour to encode additional dimensions, and make it easier to see different ‘cell behaviours.’

How to communicate cell behaviours visually
How to communicate cell behaviours visually

View Christian Stolte’s poster
Watch lighting talk

Best artwork

10 Hallmarks of cancer

by Karolína Kryštofová, Institute of Biophysics of the Czech Academy of Sciences, Czech Republic.

Karolína Kryštofová, Institute of Biophysics of the Czech Academy of Sciences Czech Republic
Karolína Kryštofová

A whimsical series of illustrations inspired by the hallmarks of cancer as described by Weinberg & Hanahan in their paper Hallmarks of cancer: the next generation (2011).

10 Hallmarks of cancer
10 Hallmarks of cancer

View Karolína Kryštofová’s artwork

Second best artwork

The human heart

by Philipp Dexheimer, Research Institute of Molecular Pathology, Austria.

Philipp Dexheimer, Research Institute of Molecular Pathology, Austria
Philipp Dexheimer

Inspired by Leonardo Da Vinci’s original way of depicting his science and ideas, this digital painting illustrates the 21st century research process to understand formation of such a delicate organ as the human heart. Cells are derived, self-organize into 3-dimensional organoid structures, and allow unique insight into heart development and physiology. Illustrating research described in: Hofbauer et al., BioRxiv, 2020 – Cardioids reveal self-organizing principles of human cardiogenesis.

The human heart

View Philipp Dexheimer’s artwork

If you’d like to take a look at all of the posters presented at VIZBI 2021, you can! Visit the poster gallery, dive into the science, enjoy the beautiful images and be amazed by the scientists’ visualization skills.

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