Top 100 papers of all time

I recently gave a talk in Singapore about publishing in Nature Protocols. When I give these talks, one of the things I explain is why Nature Publishing Group is interested in publishing methodological information. For that specific talk I had great new supporting document – an article in the previous weeks Nature about the “top 100 papers”. Of course, my top 100 papers is going to be very different from yours, but the top 100 for the purposes of this article was defined as the most cited papers of all time in the Science Citation Index, owned by Thomson Reuters.

cover_nature

When I saw the cover of Nature that week, and learnt of the news story, I knew what the most cited articles were going to be – methods papers. I knew about the high cites because when we first launched Nature Protocols we looked to see which methods papers were most cited, indicative, we believed, of people having reproduced the method and being in need of a protocol. We found such papers had amazingly high cites. An example of one of the highly cited papers serving as the inspiration for a protocol was the paper by Piotr Chomczynski and Nicoletta Sacchi on isolating RNA. We felt it was important that users of the assay understood how and why it worked, and published a protocol on the assay by the original inventors.

It will be fascinating to look in ten years’ time to see the methods being invented now that have taken off and revolutionised the way we do research. I very much hope our protocols will have helped facilitate their adoption in new labs around the world.

Nobel success

We are a little late to the party (it has been a busy month at Protocols HQ!), but Nature Protocols would like to extend their warmest congratulations to all this year’s winners of the Nobel Prize for Chemistry: Eric Betzig, Stefan Hell and William E. Moerner for their contributions to the development of super-resolution microscopy.

We are very pleased to have published a Nature Protocol from the Betzig lab earlier this year on Bessel beam plane illumination microscopy.  And we are equally pleased that the Protocol Exchange can claim a Nobel Laureate amongst its authors; the Moerner lab has published a guide to using Easy-DHPSF to measure the precise localisations of molecules in images acquired using a wide-field DH epifluorescence microscope. I would also encourage you to visit Moerner’s very informative lab website, if only to find out about the guacamole!

Cancer genomics and beyond…

About a month ago, I attended the ‘Beyond the Genome (BTG): Cancer Genomics’ meeting in Boston—my second conference as Chief Editor of Nature Protocols (my first was the 2014 ARR meeting at the University of Sussex). The BTG meeting grabbed my attention for several reasons; firstly, the topic was more-or-less within my comfort zone; secondly, there was a heavy focus on bioinformatics (a rapidly developing and important field); and thirdly, the line-up was fantastic. Fortunately, it was a small meeting so I was able to pin down several of the key speakers, including Fred Alt, Gad Getz, Peter Park, Nuria Lopez-Bigas, Mike Schatz, Nils Gehlenborg, and Rosalie Sears, and poke my head into some of their ‘labs’ (offices).

Given the bioinformatics focus of the meeting, it is perhaps unsurprising that many of them spoke about the need for easy-to-follow instructions for biologists branching out into bioinformatics and using complex computational tools for the first time. As Peter Park pointed out to me, “biologists and bioinformaticists speak different languages, and few journals seem to bridge this gap”. As it happens, some of our most popular protocols (e.g. Systematic and integrative analysis of large gene lists using DAVID bioinformatics resources, which has been cited almost 4,000 times) fit this bill perfectly, providing clear, concise, step-by-step instructions for using popular bioinformatics tools and software packages. Written by bioinformaticists, reviewed by biologists and bioinformaticists, and edited by (ex)-biologists, these protocols help researchers without a bioinformatics background to analyse their data themselves. Given the popularity of these protocols and the growing importance of bioinformatics within the biomedical sciences, this seems like an obvious area for expansion of the journal (so watch this space!)

With more than 40 talks over three days, a comprehensive overview of the BTG meeting is out of the question, so instead I will highlight a few of my favourites. On the first day, Gad Getz opened the talks with a discussion of MutSig, software developed by his group for identifying driver genes (by analysing lists of mutations and territory covered during sequencing) and building models of the background mutation processes that occur during tumour formation. Jan Korbel stepped up next, explaining the system he has set up for constructing maps of unbalanced SVs based on whole-genome DNA sequencing data. At the end of the day, Fred Alt spoke passionately about his recent work on high-throughput genomic translocation sequencing (HTGTS) strategies to identify translocations that arise from fixed DSBs, as well as sites of endogenous genomic DSBs.

The next morning, Rosalie Sears gave an interesting talk on the use of 3D tissue bioprinters to generate tumour tissue, as well as normal healthy tissue. Printer ‘ink’ 1 (consisting of endothelial cells, fibroblasts, and immune cells) is added first; printer ‘ink’ 2 (cancer cells) is then added to look at tissue distribution and assess cell interactions. Unfortunately, only a few labs have access to such advanced technology but this could change over the next 5-10 years as the set-up cost inevitably drops. Later that day, Lynda Chin talked about data she has collected using ChromHMM, a computational tool set up by Ernst and Kellis for predicting chromatin ‘states’ (based on combinations of chromatin marks) and characterizing their biological functions.

On the third and final day, Mike Schatz kicked off proceedings with a ‘bioinformatics challenge’ relating to single-cell CNV analysis. The challenge has become a regular feature of ‘Beyond the Genome’, encouraging students, postdocs, and analysts in the audience to get “down and dirty with data to solve an informatics problem as quickly as possible” (as Mike puts it). The task opened up to the floor this year (“should you chose to accept it”) was to resolve the population structure of a collection of cells, establishing which cells were in the same clone and, for each clone, which was the most highly amplified oncogene. Schatz provided data for simulated single-cell sequencing of a population of 9 cells with 250k reads per cell (all for chromosome 1 (not whole genome) at 0.5x coverage). He also provided a list of 100 candidate genes. As this coverage is too sparse to identify point mutations, the genome must be divided into “bins” (with 50-100 reads/bin) before mapping the reads and counting reads/bin. Copy number variations in a single cell can be identified as bins with significantly fewer or significantly more reads, and the population structure can be examined by finding cells with the same patterns of bin counts (see our Protocol on this).

After an initial flurry of activity as people rose to the challenge, the audience settled down to hear Nils Gehlenborg talk about the applications of StratomeX, an interactive visualization tool he developed in the Park lab to compare differences in molecular profiles across patient sets. Then, just after lunch, Schatz announced the winner of the bioinformatics challenge; René Böttcher, a PhD student in Guido Jenster’s lab in the Erasmus Medical Center in Rotterdam, was the first to solve the challenge in just over 1 hour (congratulations, René!). As the closing remarks drew nearer, Peter Park gave a fantastic talk on the different single-cell sequencing approaches, with tips on comparing data obtained using different techniques (e.g. GC bias with MDA sequencing, better read-depth stability at large scales with MALBEC than with MDA, more consistent depth at small scales with MDA, etc.). Shortly afterwards, a sea of smiling faces left the auditorium, with many promises to return next year.

Attending the HGV2014 conference — Not a sinking feeling

It was my first visit to the Emerald Isle, and most definitely worth it. However short, my three-day permanence in Belfast to attend The 15th International Meeting on Human Genome Variation and Complex Genome Analysis (HGV2014) was fruitful and thoroughly enjoyable.

I flew from London Gatwick to Belfast International Airport on an early morning flight on September 17th, never a good start of the day; not for me at least, given my long-term experience with low-cost flights that leave REALLY early in the morning bound for my native Sicily from London, the city I have emigrated to, and where Nature Protocols is based. You’ve got to suffer to go Sicily, it seems — and be mildly uncomfortable to go to Ireland.

Well, the discomfort did not last long. As soon as I climbed onto a cab just outside Belfast Airport, the friendly cabbie exclaimed “Culloden? It’s the best hotel in Northern Ireland, sir. Five stars, you know?” Culloden Estate and Spa was to double as the venue of the conference and my hotel accommodation. That review by an undoubtedly knowledgeable local sure felt nice to hear. Time to relax on the back seat of the car and take in the scenery on that drizzly morning as the cab drove for about 35 minutes through the Irish countryside, skirting downtown Belfast, before arriving at Holywood, the Belfast suburb where Culloden Estate and Spa is located. The castle-resembling hotel is immersed in quite spectacular greenery, both within and without the hotel grounds, and the hilly locale overlooks Belfast Lough, the deep inlet of the Irish Sea at the end of which is located Belfast, with its harbor. When the cab pulls over by the main entrance of the Culloden, a man in impeccable grey tail-coat and top hat opens the car door for me with a smile. Wow, that’s not the kind of treatment the average former chemistry researcher is accustomed to…

Time to check in, undo my suitcase in my room, and walk to the event room to register for the conference. There, I am handed my name badge “Baldo Lucchese – McMillan Publishers” by Sinead Lawlor, the über-efficient overseer of the conference organization. She explains to me that the conference will be attended by 126 participants, ten of them exhibitors (I think I am included among those ten), and there will be 54 research poster presentations. A pretty manageable conference size-wise from my standpoint. Among the participants are also three researchers who have written protocols for our journal, Dr. Ido Amit of the Weizmann Institute, the corresponding author of High-throughput chromatin immunoprecipitation for genome-wide mapping of in vivo protein-DNA interaction and epigenetic states, and doctors Yves Moreau and Thierry Voet of the University of Leuven, co-authors of Microarray analysis of copy number variation in single cells. Always nice to find one’s footing in that sense at a conference.

Time to dive into the talks. We are welcomed to HGV2014 by this year’s conference organizer, Dr. Mark Lawler of Queen’s University Belfast, who has also been instrumental to my attendance. As he will explain to me the next day, he moved from Dublin’s Trinity College — Mark is actually a native Dubliner (don’t they say “Dub”?) — to Belfast’s Queen’s University barely a year and a half ago, so it has been quite the struggle for him to organize HGV2014 in his new hometown. You surely wouldn’t have guessed from the results, however. I couldn’t be happier with my accommodation, the conference will progress smoothly and the talks will prove excellent.

HGV2014 is articulated into seven sessions distributed over three days, which will include a total of 36 talks and three round-table discussions. Of the 33 speakers from academia and the three from industry, the vast majority hail from either the British Isles or the US, although there are also a total of eight speakers from Canada, Italy, Belgium, Germany, and Israel.

The first of talk of the first session, “Interpreting the Human Variome”, is given by Dr. Pui-Yan Kwok of the University of California San Francisco, a member of the organizing committee and a veteran organizer of this conference. The talk, “Structural Variation in the Human Genome”, seizes my technique-oriented, Nature-Protocolly (warped?) mind. One of Dr. Kwok’s group research focuses is the study of structural variations of the human genome, variations like gene deletions, insertions, duplications, inversions and translocations. Many of these features are associated with particular diseases and disease phenotypes, but they are often hard to identify and define using whole-genome analyses, which rely on the mapping on short DNA reads ‘chopped’ from the full length genomic DNA and matched to a reference genome. This approach can provide ambiguous information when it comes to identifying, for instance, the number of times a gene is repeated in sequence along a stretch of genomic DNA, a rather important parameter to measure in some research and clinical contexts.

Dr. Kwok’s laboratory, in collaboration with BioNano Genomics Inc., a company based in San Diego, California, has developed “Genome Mapping in Nanochannels”, a technique that is particularly suited to identifying structural variations in the genome. In this approach, instead of being reduced in size, long stretches of human DNA are first nicked at several positions on only one DNA strand using a nicking endonuclease expected to nick about 12 times every 100,000 bases. These nicks are then repaired using fluorescent nucleotides and the full-length DNA molecules are then uncoiled and forced to pass through narrow parallel nanochannels, in which only one DNA molecule can fit at a time. The DNA molecules are then photographed as they move along the nanochannels. Given that the nucleotide sequence recognized by the nicking enzyme is known, that a reference genome exists, and that one obtains clear images of where the fluorescent nucleotides have been inserted along the genomic DNA stretch, a researcher can now, for instance, literally count on a photograph the number of repeats of a particular gene. Using this approach, Pui-Yan Kwok’s research group believe to have closed some of the sequence gaps in the human genome, its ‘grey areas’ of ambiguous sequence assignment that are probably due to the presence of structural variations.

The following Session II, “Tracing and Targeting the Tractable Cancer Genome”, was in principle a bit too focused on clinical research from the standpoint of Nature Protocols remit; nevertheless, it did rouse my curiosity. The lecture by Dr. Lillian Siu of the University of Toronto was particularly thought-provoking from my layman’s point of view. Lillian Siu’s research focuses on the study of inter-patient and intra-tumor genomic heterogeneity in the context of cancer. It has been known for years that cancer patients with specific genetic signatures tend to respond (or not respond) to specific drug treatments in a somewhat predictable fashion. Such genetic heterogeneity is the basis of the so-called personalized medicine approach to treatment. Dr. Siu sketched for the audience the clinical trial designs that take into account genetic heterogeneity. At one end is the ‘umbrella trial’, in which all participants share the same tumor type (for instance lung cancer), according to histology results, and they are assigned to different drug treatments based on their relevant genetic aberrations. At the other end is the ‘basket trial’, in which patients with different cancers based on histology are pooled together into treatment groups based only on their genetic aberrations, irrespective of histological evidence. Finally, she described the N-of-1 trial design, which consists of a comparison of the results of two different treatments applied to the same patient: in this trial design, time-to-progression in a patient on a genotype-matched treatment is compared to the same parameter in the same patient when he/she was on a prior, and presumably non-genotype-matched, treatment.

At the end of this talk, a calculatedly provocative question from a member of the audience rang: “So, are randomized, controlled trials a thing of the past?” Well, given my background as former associate editor at Nature Reviews Nephrology and Nature Reviews Gastroenterology and Hepatology, this question made me sit up: aren’t they the gold standard for medical trials? Lillian Siu clearly did not want to be drawn into sweeping generalizations, but she explained that, in a genotype-matched drug clinical trial, tumor responses may be sufficiently significant and objective for conditional drug approval of the drug to be granted in some cases. In this context, she thought that, prospectively, randomized trials are likely to become less and less prevalent, given how exhausting they can be for research resources as well as for patients. It sure was a treat to witness this exchange…

The next day’s morning session was entitled “Phenomes, Genomes and Archaeomes: Solving the Conundrums”. I have had a small obsession for studies on ancient DNA genomics for a while, so it came to no surprise to me that I found the talk “Ancient Population Genomics: Do It All or Not At All” by Dr. Dan Bradley of Trinity College Dublin, particularly exciting. As Dan Bradley reported, a key difficulty when working with ancient DNA is that when collecting DNA from a typical ancient human bone sample, only about 1% of it is DNA from the original owner of the bone, the rest is leftover from various contaminations. He and his research group have used bioinformatics tools that enable researchers to sift through the sequencing data from ancient DNA that does not need to be particularly pure to infer which sequences pertain the individual to whom the biological sample belonged and which are, instead, due to contaminants.

Dan Bradley reported results from his group and collaborator’s research that help shed some light onto the population and cultural changes that Europe underwent between the Mesolithic through to the Iron age, via the Neolithic and Bronze age. One of the overarching questions his group has been trying to address is whether age-defining technological/cultural innovations were exchanged ‘osmotically’ between populations or whether such dramatic changes, for instance from a hunter-gatherer culture to an agricultural one, are associated with new human populations displacing the previously resident ones. Although their data on this subject appears to be a bit of a mixed bag, evidence seems to indicate that in most cases an age-defining technological or cultural shift also coincides with a population replacing or pushing aside another. Well, it does make sense in a sad sort of way.

Session IV “Answering the Global Genomics Challenge — Time to Step up to the Plate”, late morning on September 18th included talks that focused on ongoing international efforts to sharing genetic data across research centers and across countries to share evidence about genetic mutations and how they may be associated with the onset of, or the predisposition to, disease. Dr. Anthony Brookes of the University of Leicester, among other projects, recounted the design and purpose of Cafe Variome project. This project in particular stuck to my mind because the previous day I had had the chance to talk about it with Dr. Owen Lancaster from Brookes’ lab, who was presenting a poster describing Cafe Variome.

As Owen also clarified for me, Cafe Variome tries to shift the basic nature of the problem of accessing data on mutations and phenotypes that, despite their high potential usefulness, are currently not being openly shared due to legal, ethical or competitive reasons. Cafe Variome tries to clear this roadblock by providing a platform whereby the existence rather than the substance of the data is made accessible to subscribers. Once these discovery ‘hits’ are achieved, the platform facilitates exchange of the data in the form the most suits the relationship between data requestor and data owner: data summaries, data displays, data links, data owner contact details, or a form for data automated data request and subsequent provision.

Presently Cafe Variome, which is hosted by the University of Leicester, supports networks of rare disease diagnostic laboratories or research consortia that share an interest in certain causative genes or diseases, know and trust each other to different degrees, and wish to have a full picture of what records and information exists across the collaborating network. Six such federations are currently trialing the platform, and, Owen explained, one of them will be shortly opening up their content also for public discovery. Well, fascinating stuff for someone like myself who is a bit obsessed with data sharing and privacy, particularly when it comes to genetic make-up. Sooner or later I should write a post on that too…

Session V, “Improving our Health: Time to Get Personal”, was particularly engaging. In the first talk, “Personalised Cancer Medicine: Are We There Yet?”, Mark Lawler described the efforts and purpose of the European Alliance for Personalised Medicine, of which he is a member, an international association that aims to promote personalized medicine and its delivery in the health systems of European countries and to develop patient-centered European translational research platforms. It was clear how much enthusiasm and personal stake Mark has in promoting personalized medicine in the context of cancer treatment, but from the last talk of the session it was also clear, at least to me, that he does not take himself overly seriously, and he is quite open to discussion.

The last ‘proper’ talk of this session, aside from being quite entertaining, was rather unusual in that it was given by Professor Timothy Caulfield, a researcher in the area of health law, biotechnology policy and bioethics. The title of talk, “Marketing the Myth of Personalized Prevention in the Age of Genomics”, already conveys a lot of the tone of this presentation. Timothy Caulfield is a bit of a skeptic of personalized medicine, and he started his lecture by thanking Mark Lawler for inviting him to talk at the conference despite his stance and, presumably, he implied, as a way to kick-start a lively discussion. Caulfield does not believe that the prevention of common diseases is likely to be affected by personalized medicine. Progress in genetic research, he argues, has been hailed as heralding a ‘revolution’ for decades now. But this revolution has yet to materialize. He is also rather offended by what he calls ‘science-ploitation’, via which for-profit companies, even those commercializing beauty creams, for instance, claim that their products can be targeted and tailor-made to suit the personal needs of customers based on their genetic make-up. A number of sleek commercial ads with portentous ‘scientific’ claims succeeded each other on the screen at various times as Caulfield gave his presentation.

The core of his objecting to the promotion of, for instance, widespread genetic testing in the healthy population in the wake of the personalized medicine ‘revolution’ lies in the research that points to the fact being made aware of a predisposition to a particular condition or disease does not change the behavior of individuals to any significant or measurable level. Focus on genetic testing and personalized approach when it comes to public health policies, he argues, shifts responsibility from the political and social level to the individual, when it is proven that only ‘general’ policy decisions can spur changes in social attitudes and, ultimately, change the behavior of individuals. To drive home the point about science-ploitation of the concept of personalized medicine, Caulfield recounted how he had had his genome sequenced by an American commercial company. Caulfield shared with the audience some of the results he had obtained, which meant that he had a slightly elevated predisposition, compared to the average, to a few medical conditions. The ‘bespoke’ advice that he received from the commercial company was to exercise, drink in moderation and not smoke… So much for the personalized prevention regime; point made, I’d say. Science-ploitation… That’s a word that I’ll end up using a lot, I’m guessing, sorry Professor Caulfield.

This session was capped by a round table discussion entitled “Prime Time for Personalised Medicine”, which had a TV talk-show format, in which the chair, conference co-organizer Dr. Stephen Chanock of the National Cancer Institute, Maryland, moderated the discussion of a five-membered panel that included also Timothy Caulfield, Mark Lawler, and Lillian Siu. Of course different points of view and opinions were shared during the discussion, but the panel ultimately agreed that the sensationalization and mis-representation by the general interest and popular press and by commercial companies of the results and implications of genetic research are a significant problem for the scientific community. However understandable sometimes, these tendencies could ultimately harm genetic and genomic research itself. A tentative solution proposed by several of the panelists and a few members of the audience was for scientists to become more actively involved in the public discourse about genomic and genetic research, so as to offer additional means for the public to correctly frame this discussion and interpret the significance of research findings. Proposals were made that scientists should try, for instance, to make themselves more savvy and effective in the use of social media like Twitter, although some confusion immediately ensued this proposal as some panelists and members of the audience couldn’t initially agree on the character limit of twitter feeds. Nevertheless, it was an encouraging start all in all, given that the matter was eventually correctly settled: that limit is 140.

An excellent conclusion of the day’s lectures, before the gala dinner of the conference, which took place at the Titanic Signature Building, an attraction that opened to the public in 2012 and is located in the section of Belfast harbor where the RMS Titanic was built. This building, which is exactly as tall as the Titanic’s highest tip, hosts a multi-storey, multimedia museum themed on the building and ultimate sinking of the Titanic. Us conference participants were taken on a guided tour of the museum that chronologically followed the Titanic (mis)adventure and that culminated in a viewing of the striking underwater footage of the wreck of the Titanic shot from a deep-sea submersible in the 2004 expedition undertaken by marine explorer Robert Ballard together with the National Oceanic and Atmospheric Administration (NOAA). Naturally, a very fancy and very satisfying dinner followed, made particularly enjoyable by light conversations with my table mates, researchers from Spain, the Philippines via California, Britain, and Sweden.

The last day of the conference was dedicated to sessions VI, “Understanding the Evolving Genome”, and VII, “Next-Gen ‘Omics and the Actioanable Genome”. It was also the day of two Sponsor Presentations, one of which was by BioNano Genomics Inc.’s Dr. Han Cao, “Towards the True Contiguity Resolving the “Dark Matter” of Genome”, which covered also the technique already introduced on the first day of the conference by Dr. Pui-Yan Kwok for Genome Mapping in Nanochannels, and that BioNano is currently applying also to the study of non-human genomes. As mentioned, pretty fascinating stuff from the point of view of a technique-biased scientific reporter.

Talking about techniques, the last day of HGV2014 was also dedicated to giving awards to the best posters. In advance of my attendance of the conference, Nature Protocols had proposed to award a one-year online personal subscription to the journal to the presenter of the poster describing the most interesting technique, and Mark Lawler had been immediately enthusiastic and supportive of the idea. As I walked around speaking with poster presenters, I also got to chat with Nature Protocols authors Ido Amit and Thierry Voet. They were possibly being nice, but they both told me that they enjoyed their experience as authors of our journal, and they considered Nature Protocols a very useful resource. It may not be statistically significant with just two subjects, but they both ended up putting more work than they had anticipated into their Protocols, but they felt it was entirely worth it. A quiet sigh of relief on my part welcomed the conclusion of their reflection. Surprisingly, both of my interlocutors, to whom I spoke separately, by the way, also felt that it would be of great help if Protocol authors could submit video tutorials alongside their manuscripts. Fact is, however, that authors can already do so, and a minority of the Protocols we publish do come with supplementary information in the form of videos. Clearly, we must do more to make our authors more aware of this possibility.

Going back to the posters, maybe unsurprisingly, Nature Protocols, in its yours truly incarnation, decided to award the prize for the poster describing the most interesting technique to Dr. Angel Mak, a post-doc in Puy-Yan Kwok’s University of California San Francisco laboratory, for the poster entitled “De novo genome assembly and structural variations detection by genome mapping in nanochannel arrays”. Of course, the technique described in the poster is none other than Genome Mapping in Nanochannels, already described in Dr. Kwok’s lecture two days earlier. My sincere congratulations on your research work Angel! But I had a wonderful time looking up all the posters and talking to several of the presenters. Very exciting work being presented by each poster, and thank you to all the researchers I spoke to, none of whom let transpire any disappointment at the dumbness of some of my questions.

It was Friday after 4 pm by the time I announced the winner of Nature Protocols’s prize, and it was time for me to catch a cab to go to the airport. I had to give a miss to the Irish Night — Whiskey Tasting Experience and Culture Night Performance Including Broadway Acclaimed Actor Eilin O Dea, organized for 5.30 pm that evening. A London night was beckoning for me; not that I had anything special planned, in fact I had nothing at all planned, but even with my relatively early flight from Belfast, I did not reach home till 11 pm that night. Sadly, I’m too old for anything more lively than that. And hey, now I’ve got an excuse to go back to Belfast and complete the Northern Irish experience…

Thanks a lot Mark and thanks a lot HGV2014 participants for the excellent time all around!

Microscopy Madness in Bangalore

Editorial note: Welcome (and a big thank you) to our first ever guest bloggers – Professor Hari Shroff and Dr Abhishek Kumar! Their post perfectly illustrates why we at Nature Protocols are so passionate about helping to ensure detailed technical knowledge and experience is transferred from one lab bench to another, from senior to junior researchers, across the globe. Enjoy their story – and be inspired by the achievements of the students!

 

A guest blog post by Hari Shroff and Abhishek Kumar

Optical imaging is experiencing an explosion, and not a month goes by without the publication of some new microscopy method. This can make it difficult to keep up, even for a lab like ours1, whose business is to create new imaging tools for use in biology. Even more challenging is the lag between the development or prototype of a new technology, and deployment of the tool in a form that biologist can easily use. Technology translation can take years and commercial adoption of a new method even longer- if it happens at all.

We are thus grateful for the opportunity to publish a do-it-yourself, easier-to-use implementation of our dual-view selective plane illumination microscope (diSPIM)2, a high-resolution light-sheet system, in Nature Protocols3. Apart from employing fiber-coupled excitation (making it easier to use a variety of commercial laser sources, and improving the flexibility and alignment of our device) and describing the use of GPU-ready processing software (speeding up image processing tremendously compared to our earlier efforts2), the protocol provides step-by-step instructions on construction, alignment, and imaging at a level of detail impossible to provide in our previous publication.

Of course, there’s no better test of a method than trying to put it into practice – which we were lucky to do recently at the 6th annual microscopy course in Bangalore, India at the National Center for Biological Sciences (NCBS). The course runs for one week, and students alternate between lectures and labs. Working days are long, with most days 12-14 hours. At the end of the course, students pick up a short independent project, putting what they learned at the course into practice.

When we arrived in Bangalore, NCBS staff had pieced together much of a diSPIM, based on an earlier version of the Protocol that we had sent them. We spent most of the week checking various components and fixing small issues. By the time the final weekend rolled around, we decided to rip it up and build it again from scratch – a great student project. In about 6 hours, course participants were able to assemble and align a functional microscope (well, almost functional as we had some trouble with the piezos…) by following our Protocol – perhaps the first light-sheet system in India but certainly the first diSPIM.

The results of their labors (a total time of ~6 hours) are entertaining (sped up ~65x and condensed to ~4 minutes), and can be viewed here.  We hope you enjoy it – for maximizing the audio-visual experience, we recommend turning your speakers up!

 

  1. https://www.nibib.nih.gov/about-nibib/staff/hari-shroff
  2. Wu, Y. et al. Spatially isotropic four-dimensional imaging with dual-view plane illumination microscopy. Nat Biotechnol. 31, 1032-1038 (2013). DOI: 10.1038/nbt.2713
  3. Kumar, A. et al. Dual-view plane illumination microscopy for rapid and spatially isotropic imaging. Nature Protocols 9(11), 2555 – 2573 (2014). DOI: 10.1038/nprot.2014.172

 

A burst of activity on the Protocol Exchange

In the last month we have pushed live 9 new protocols on the Protocol Exchange!

– Long-term calcium imaging of ASJ sensory neuron controlling cold tolerance in Caenorhabditis elegans

– A spinnable and automatable StageTip for high throughput peptide desalting and proteomics

– Cold tolerance assay for studying cultivation-temperature-dependent cold habituation in C. elegans

– Protocol for delivery of macromolecules using dfTAT into live cells

– Mouse meninges isolation for FACS

– Microglial Sholl Analysis

– Modified paired end rapid library preparation protocol for 454 GS Junior 8 kb library preparation using Covaris g-tubes and BluePippin electrophoresis

– Purification of influenza virions by haemadsorption and ultracentrifugation

– Multi-parameter assessment of thrombus formation on microspotted arrays of thrombogenic surfaces

One of the limitations of the Protocol Exchange has been that it is difficult to work out how many times one of the protocols has been cited. We have recently realized that google scholar can capture this information, and it may be possible to extract a citation report by using the DOI as the search term.

For example:
If you wanted to find out how many times the protocol “Anisotropic Mobilities in Organic Semiconductors” had been cited, you could paste 10.1038/protex.2013.070 into the search field of google scholar.

google scholar 1

The search will then give the following output:

google scholar 2

I am not sure how this works and perhaps the data should be taken with a pinch of salt, but if you have an Exchange Protocol, you might want to perform the search and see what it spits out!

 

 

 

 

Nature Protocols authors receive the Nobel Prize in Physiology or Medicine

Congratulations to Nature Protocols authors James E. Rothman and Thomas C. Südhof, who alongside Randy W. Schekman have been awarded this year’s Nobel Prize in Physiology or Medicine “for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells”, according to yesterday’s press release by The Nobel Assembly at Karolinska Institutet.

This year’s award acknowledges the fundamental contribution that research by Randy W. Schekman, James E. Rothman and Thomas C. Südhof has provided to the elucidation of the system that precisely controls the vesicle-based transport and delivery of cellular cargo within cells and from the cells to the outside environment. This traffic control is essential for the correct functioning of cells, and defects to it are known to occur, for instance, in diabetes and in a number of neurological and immunological disorders.

In detail, Schekman’s work has been instrumental in identifying the three classes of genes that control the cell’s transport system; Rothman, the author of two Nature Protocols articles, shed light on the mechanism by which the formation of specific protein complexes allows vesicles to dock and fuse with the correct target membranes; and, through his work of nerve cells, Südhof, the author of one Nature Protocols article, enabled the identification of the calcium ion–regulated molecular machinery that directs proteins to bind vesicles to the outer membrane of nerve cells, as a preliminary step to the release of neurotransmitters.

Dr. Südhof’s contribution to Nature Protocols is not specific to the research just mentioned, but it does provide detailed instructions on how to perform high-throughput gene expression profiling in individual neuronal cells using quantitative PCR. The approach covered by this protocol enables the investigation of hundreds of transcripts from a single neuronal cell, and it can be used to characterize, for instance, lineage-specific, reprogrammed neuronal cells.

One of the main areas of Dr. Rothman’s lab research is the protein superfamily known as SNAREs, which are present in yeast and mammalian cells. The key job of these proteins is to mediate fusion between vesicles and the cell membrane or the membrane of a cellular compartment. SNAREs are often subdivided into two categories, vesicle or v-SNAREs, which are embedded on the surface of vesicles, and target or t-SNARES, which are located on the surface of target membranes. Interaction between v-SNAREs and their t-SNARE counterparts directs the fusion of vesicles to target compartments through the formation of a three-protein complex formed by cognate SNAREs anchored on ‘opposing’ membranes.

The structure of a v-SNARE nanodisc

The structure of a v-SNARE nanodisc. The green ribbons represent copies of a v-SNARE.

Dr Rothman has co-authored two protocols published in our journal, both useful for the study of SNARE proteins. A 2012 paper describes the preparation of fluorescently labeled v-SNARE liposomes and t-SNARE–reconstituted planar, supported bilayers that can be used to monitor docking and fusion events by conventional far-field epifluorescence or total internal reflection fluorescence microscopy. One year later, almost to the day, we published a second protocol co-authored by Dr. Rothman. In this article the authors detail the preparation of nanodiscs of fixed (small) size that contain fluorescent lipids and copies of a v-SNARE. Upon fusion of one such nanodisc with a liposome containing the cognate t-SNAREs, the occurrence of a fusion event can be quantitatively monitored following the increase in fluorescence caused by the dispersal of the initially quenched fluorescent lipids from the nanodisc into the non-fluorescent, and much larger, interior of the liposome.

The fusion process between a v-SNARE nanodisc (bottom) and a t-SNARE liposome (top)

The fusion process between a v-SNARE nanodisc (bottom) and a t-SNARE liposome (top)

 

Well, our heartfelt congratulations to Randy Schekman, James Rothman and Thomas Südhof for their achievement. And please forgive my lack of modesty when I point out that it also feels good to have it confirmed yet again that Nature Protocols authors are among the very best in their fields.

CAUTION: Don’t mix concentrated nitric acid with organic solvents!

Radiolabelling with copper-64 (or any other metal cation radioisotope) is done by attaching a metal chelating group to the probe of interest. In 2006, we worked with Thaddeus J Wadas & Carolyn J Anderson to publish a protocol for radiolabelling peptides with copper-64 which included a procedure for making sure that the reaction tubes and pippette tips used for the labelling were free from any other metals that might compete with copper-64 for coordination by the chelator (Box 1 in the protocol). This procedure involved washing the equipment with nitric acid, followed by rinses with ethanol followed by diethyl ether.

This is actually potentially hazardous, and the authors would like to make the following precautionary statement:

CAUTION:  When removing trace metal contaminants from pipette tips or reaction vials with 1:1 concentrated nitric acid:ddH2O, make sure no organic solvents like ethanol or diethyl ether are inadvertently mixed with the nitric acid waste.  An explosion occurred when this happened at a lab using this procedure.  Fortunately, nobody was injured.

In fact, it is possible (and advisable) to not use organic solvents for this process at all. The text for Box 1 should instead read:

BOX 1 | REMOVING TRACE METAL CONTAMINATION

Working on the tracer level requires that the reagents and vessels used be as free as possible of trace metals. To achieve this, pipette tips, reaction tubes and caps can be acid-washed by following the steps below.
Alternatively, trace metal free reaction tubes and pipette tips can be
purchased.

Removing trace metal contaminants from reaction tubes, caps and tips
1. Soak the tubes and caps or tips in a 1:1 mixture of concentrated nitric
acid and ddH2O (greater than 18 MΩ resistivity) for several hours with
periodic mixing, and then drain.
2. Rinse the tubes with ddH2O, and drain.
<CAUTION> It is recommended that ethanol and/or diethyl ether not be
used to assist in drying the tubes, as even small amounts of these
organic solvents mixed with 1:1 nitric acid ddH2O can cause an explosion.
3. Place in a container and dry in an oven at temperatures below 50 deg C.

Removing trace metal contaminants from reaction buffers and other
solutions
1. Prepare the solution(s) or buffer(s) to be used.
2. Add Chelex resin (10 g l-1) to these solutions.
3. Stir for several hours or overnight at room temperature.
4. Filter through a Corning 1-liter filter system (pore size 0.2 mm).

 

………….

Related explosions:

It will probably not surprise you to know that this is not the first time that such things have happened with nitric acid and oxidisable organics. Here are some links to related anecdotes:

Safety Chat: Nitric Acid Waste
(Lawrence Berkeley National Laboratory, 2009)

Explosion at U. Maryland: Another Nitric Acid Oopsie
(University of Maryland, 2011)

The flaming apron that sparked the invention of gun cotton and the motion picture industry
(a kitchen in Switzerland, 1845)

 

…………………

Note added on 17 October 2013:

A corrigendum for this protocol has now been published (11 October 2013). Box 1 has been corrected in the pdf and the online version of the protocol.

https://www.nature.com/nprot/journal/v1/n6/box/nprot.2006.431_BX1.html

 

 

IF all over again

If you can meet with Triumph and Disaster
And treat those two impostors just the same;
If you can bear to hear the truth you’ve spoken
Twisted by knaves to make a trap for fools,
Or watch the things you gave your life to, broken,
And stoop and build ’em up with worn-out tools:
Rudyard Kipling

Yes it is that time of the year again when Thomson Reuters publishes its Journal Citation Report (JCR) and everyone involved in science publishing gets obsessed with Impact Factors (IF). I’m not going to go through the arguments about how little Impact Factors really mean, and I’m certainly not going to try and forecast the health or otherwise of a publishing venture based on a change of 0.3 in its IF. But I thought you might want to know what Nature Protocols’s 2012 IF is. So cue drum roll …

It’s 7.96 down a couple of points from last year’s 9.92

Or

It’s 11.74 up from last year’s 10.20

Nothing is simple when it comes to Impact Factors. They are sort of an estimate of the average number of citations that a paper in a particular journal gets, but they are actually the number of citations a journal gets in a year to articles published in the previous two (or five) years divided by the number of articles published in those years that it seem appropriate to cite (‘simples!’). Herein lies the apparent contradiction in the numbers I gave above. Nature Protocol’s Impact Factor based on citations in 2012 to protocols published in 2010 and 2011–the two year impact factor (IF2)– is 7.96. The Impact factor based on citations in 2012 to protocols published between 2007 and 2011–the five year Impact Factor (IF5)–is 11.74.

For most journals there isn’t a whole lot of difference between the IF2 and the IF5, certainly less than 10% so when someone says Impact Factor they normally mean IF2. There are a few journals with big differences between the two values. The journal with the highest IF2 of all, CA: A Cancer Journal for Clinicians published by the American Cancer Society, has an IF2 of 153.46 and a IF5 of 88.55 which I interpret as meaning that what it publishes is extremely relevant for a couple of years (and so is highly cited) but after that it quickly loses its importance.

Conversely that Nature Protocols has a higher IF5 than IF2 could be taken as an indication that the protocols we publish remain relevant well beyond the first years after presentation. A measure that might bear that out would be the cited half-life of the journal. This is defined as the median age of the articles published in Nature Protocols that were cited in a given year (i.e. 2012). For Nature Protocols it is 4.9 (in 2011 it was 4.2), but that really doesn’t say a lot as Nature Protocols is a relatively young journal which has only been in existence since 2006. The maximum value for cited half-life we could have got would have been 6 and if there was no change in the rate of citation of our protocols over time a value of 3 would have been expected. We will need to be at least in our teens before I will put much store by cited half-life.

There is another confounding factor in all this for Nature Protocols and its name is DAVID.

In December 2008 we published online a protocol by Richard Lempicki and colleagues at National Cancer Institute at Frederick, Maryland called “Systematic and integrative analysis of large gene lists using DAVID bioinformatics resources” (Nature Protocols 4, 44-57 doi:10.1038/nprot.2008.211 (2009)). It is our most cited paper having been cited more than 3,000 times. It is in fact the most highly cited paper from any Nature  journal, including Nature itself, published in 2009 (yes I know it was published in 2008 but it was in the January 2009 issue of the journal and so that makes it officially a 2009 paper). In 2012 alone it was cited upwards of 1,000 times. However since it was published in 2009 those citation do not contribute to our  IF2 although they do to our  IF5. It is difficult to get the figures to calculate the exact effect of a single paper on IF but a fair approximation would be to say that had those 1,000 citations been included in the calculation of our IF2 then it would have been a bit less than 3 points higher, while excluding them from our  IF5 would reduce that by about 0.8 making both values in the region of 10.9.

Yep, you’ve got it! Citations to a single paper seem to account for all the difference in our Impact Factors. Which simply shows again that IF may be a great poem, but it is a poor measure of the scientific literature.

 

Protocols Discussion Forum is Moving

As you may or may not know Nature Protocols has a Discussion Forum where anyone having problems with their experiments can ask questions and hopefully receive helpful advice from other researchers with some experience in whatever is causing the problems. For the last several years this has been hosted on Nature Network but as of, well right about now, we are shifting its platform to a Google Group.

We have always thought of Nature Protocols as more than a journal and we try to engage with our readers to help them in their research. We have done this through commenting on our manuscripts; this blog; our YouTube channel and the discussion forum. We are always on the look out for technologies that might be helpful.

That’s why we are now moving the Discussion Forum onto the Google Groups platform.  We hope that this will greatly improve the effectiveness of the discussions by making it even easier for anyone to become involved in the forum. It should be easier to access on mobile devices, and easier to post on as comments can be made and discussion topics started simply by sending an email to nature-protocols-discussion@googlegroups.com.There are other technical advantages for us as well, not least a better spam filtering system so hopefully far fewer topics or posts will be offering fake passports for sale!

There are two ways to access the new look discussion forum, either through the Discussion page on this blog or directly at Google Groups . We very much hope that this move will increase the usefulness of the Discussion Forum by making it easier for researchers to take part, easier for the topics to be found by people searching for answers using search engines, and easier for topics to be connected to from throughout the Web.

The Current Discussion Forum isn’t going away but will remain as an archive. However it will not be possible to post new topics or reply to existing threads. I have however copied across all discussions started this year into the new platform as well as some of the most active from 2012. If there are any threads that you would like to see continued please let me know and I will copy those across as well.

I hope that everyone will find the new forum at least as helpful as it’s predecessor.

So, what shall we talk about? As an eponymous fictional talk show psychiatrist didn’t quite say:

“We’re listening.”