Structured illumination: the Bruce Wayne of the super-resolution league?

noBell

A week before Eric Betzig shared the Nobel Prize with Stefan Hell and William Moerner for super-resolution fluorescence microscopy, I listened to him give a talk at an imaging conference in Edinburgh, Scotland. The talk focused on Structured Illumination Microscopy (SIM). The idea that SIM does not belong in the same category as STED and super-localisation techniques, Betzig repeatedly stressed, is ludicrous. Betzig is so convinced of this notion that his group has moved to focus on developing applications of SIM for live imaging.

The best image resolution obtained by SIM is only about twice as good as that imposed by the normal diffraction limit, paling in comparison to the hundred times improvement sometimes seen by STED, but SIM is faster and runs on a more efficient light budget than the rest of the super-resolution stable. This creates non-trivial advantages when the subject is alive and preferred to stay that way. Biologists can learn a lot from studying something which is formerly alive, but much more from cells in the dynamic travails of life.

If Betzig is convinced working with SIM is more amenable to practical application than other super-resolution techniques, such as Photo-Activated Localisation Microscopy, the technique that won him the Nobel Prize, why was it left out when it came time for the Swedish Academy of Sciences to recognise super-resolution? The answer may lie more in the rules and peculiarities surrounding the awarding of a Nobel than on the scientific relevance and impact, but you wouldn’t guess that from reading the Scientific Background on the Nobel Prize in Chemistry 2014.

In the published view of the Kungl Vedenskapsakademien, SIM, “Although stretching Abbe’s limit of resolution,” remains ”confined by its prescriptions.” In other words, the enhancement beyond the diffraction limit achieved by structured illumination is just not super enough. In principle the resolution of STED can be improved without limit by switching your depletion laser from “stun” to “kill” (i.e. increasing the depletion intensity). Likewise, super-localisation is essentially a matter of taking a large number of images of blinking fluorescent tags. Improving the effective resolution in super-localisation is a case of tuning the chemistry of your fluorescence molecules and taking an enormous amount of images. In reality, practical problems prevent further resolution improvement long before the capabilities of these techniques reach the resolution of a Heisenberg’s microscope, for example. However, SIM is subject to an “aliasing limit,” which, for the nonce, seems to be as hard and fast as Abbe’s and Rayleigh’s resolution criteria were (and largely still are, with the exception of fluorescence techniques) for the last hundred years.

As a rule with only one exception I know about, a Nobel Prize is not awarded post-mortem. Despite the justification proffered in the official background, Mats Gustaffson’s untimely death in 2011 may have played a major role in the exclusion of super-resolution structured illumination microscopy. Combined with the cap of three people sharing a single Prize, this left Rainer Heintzmann and the late Mats Gustaffson without Nobel recognition of their contributions to super-resolution. Even with the somewhat arbitrary adjudication over what it is to truly “break” the diffraction limit, it seems curious that one of the super-res laureates has moved almost entirely away from the prize-winning technique he invented, preferring instead the under-appreciated SIM. The Nobel Prize is arguably the penultimate distinction in scientific endeavor, and it seems beneath the station of the prize for its issue to be governed so strictly by arbitrary statutes. Then again, the true reward of scientific achievement is not a piece of gold and a pile of kronor, but the achievement itself. The universe isn’t altered whether you win the Nobel Prize for uncovering one of its little secrets, the truth of the secret will remain regardless.

‘Anonymous’ has an intriguing comment about why super-resolution is still not finding common use in biology research here.

Interesting note: unlike STED and PALM/PAINT/STORM, structured illumination can be applied to quantitative phase imaging

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The Nobel Prize and mental health

Ah fall, the time when an elder scholar’s fancy lightly turns to thoughts of Sweden. Presumably all scientists at one time or another in their career dream of autumn slumber jarringly interrupted by a pronouncement that will ensure their impact has been indelibly left on their field for decades to come: the Nobel Prize.

A Nobel Prize comes with an 8 million kronor cash prize (as of 2012), or about 1.25 million USD. Far more than that, the prestige and standing that come along with the receipt of said prize insures no shortage of seminar invitations, honorariums, and appointments, all but guaranteeing that a winner will never have to “work” another day in their life if that’s what fries their biscuit. A Nobel Prize winner may soon find themself at real risk of succumbing to the glamouros life of resting on their laurels. For some, all that fame and glory can go to their head, potentially leaving their mind a bit less comprehensible. This brings us to the topic of this essay: the world-infamous Nobel co-winner in Chemistry from 1993, Kary Mullis.

For those that have read Kary Mullis’ (self-penned, he fired his co-writer) autobiography, you will remember his accounts of being abducted by an extraterrestrial in raccoon form, his persistent belief in astral projection, and his insistence that HIV and AIDs are not causally linked among other -quite odd- convictions. He may have been attempting to instil in the reader contrary lessons in the role of scepticism and credulity in scientific thinking, he may have recounted events and reality to the best of his understanding, or he may have been just fucking with his readers. Probably all of those options and a few others come into mixed play throughout the autobiography. Perhaps a look at Dr. Mullis’ brief foray in astrophysics may provide some insight. Kary Mullis’ first publication as a biochemistry grad student came in 1968, appearing in the journal Nature: The Cosmological Significance of Time Reversal..

It is, I think, among Dr. Mullis’s proudest accomplishments. He even references the article in his Nobel Prize speech. Now considered to be a bit of rubbish, fuelled by the psychoactive recreations Dr. Mullis is now famous for, which enhanced his “perceived understanding of the cosmos.” The closest I can find to a full text of the article is a grainy scan on Readcube, the preview is limited to the first few paragraphs. Mullis’ article resulted in heavy press coverage, presumably as a result of perceived credibility from specialist language in a generalist journal, obscuring what seems to have been a very vague theory. The tenets of the hypothesis are nearly entirely untestable by experiment: the “time-reversal” described in the article makes it impossible for particles to interact with those of the opposite time sense, namely us. Oh, and time reversal happens inside a mass only after it collapses to a black hole, so “Seen from the outside there will be no effect” (quote from the article). It is just weird enough to leave me wishing I could read past the paywall.

The moral of this story is that one shouldn’t trust everything you read, even (especially?) if it is found in Nature or Science. Resonates well with some of the high-profile rebuttal(s) of prominent articles of the last few years.