Hello again! Welcome back to the LuxeSci Podcas, a podcast to re-ignite your wonder by exploring the intersection of science and luxury. I’m, Dr. Lex, PhD, podcast host and lover of anything sparkly. For our second episode, I turned that love of sparkle into an episode about sequins! Aside from my love of shiny objects, the reason I chose this topic for the second episode is that I’ve recently been looking through photos of the Spring 2022 fashion weeks and sequins were everywhere!
Two stand outs for me were:
Dior used sequins in their rainbow miniskirts that were an ommage to 60s mod
And now, to Chanel...For me, Chanel’s use of the sequin is always masterful. Using them as part of the tweed, adding them to short, shorts and midi skirts for a more modern flare, and the sheer little black dress with the long black vest...brills
Of course, its not just the big fashion houses that rely on sequins
Pantora has a beautiful animal print and sequin suit
So what is a sequin….
Small, disk-shaped shiny bead
Sequins have a center hole
Spangles have a hole near the top
Paillettes are very large and flat
The name originated from the Arabic word sikka “coin” later becoming Venetian zecchino (meaning Venetian ducat coin). Name was not being used much after the coins stopped being minted but then the word was taken up in France to mean shiny beads. In the 19th century, sequins were made out of shiny metal
Seems that humanity has always loved shiny adornment
Evidence of gold sequins on clothing as early as 2500 BC in the Indus Valley
Tutankhamun had solid gold sequins sewn into his royal garments
Sequins made a resurgence in the 1920s after the discovery of Tutankhamun’s tomb and the resulting Egyptomania.
Sequins surged again in the late 1960s and have continued to be popular and really there wasn’t a time when sequins weren’t part of the fashion
Originally made from metal, then a short period in the 1930s when they were made from gelatin (which would melt if they got too warm or wet). Eventually polymers were created and perfected resulting in the vinyl plastic versions we see today
So those are the basic of sequins and now on to the science
The Sequin Illusion
We’re going to start with another link to visual processing, since I know you all enjoyed that so much last week.
The sequin illusion is akin to the Hermann Grid Illusion, this is where you see dots in between the spaces of a grid of solid squares. The sequin illusion happens when those solid squares are change to dotted line squares. Now, instead of the dots appearing in between the shapes, they appear within the shapes, kind of like a grid of sequins.
In a “Short and Sweet” communique in iPerception, Kuo and Tseng played with the pattern in terms of colors and shapes and found evidence that this illusion is driven by alternating bright/dark contour (contrast). The authors further posit that this happens early in the visual pathway prior to the V1 and V4. Just a note that you can see this in real-life in patterns in fabric and wall paper
DNA spikes
How DNA replicates (starting at the very beginning). https://www.khanacademy.org/science/ap-biology/gene-expression-and-regulation/replication/a/molecular-mechanism-of-dna-replication
DNA is a double-stranded nucleic acid and so DNA replication is called semi-conservative with each strand of the double helix acting as a template for making a new, complementary strand
An enzyme cleaves the two strands of the DNA at a specific starting point, then specialized proteins bind to the DNA to keep it from re-binding and helicase keeps the process moving by unwinding the DNA as the replication progresses/
DNA polyermases are the enzymes that attach new nucleotides (A, T, C, G) to the new strand
DNA nucleotides form exclusive relationships. A always binds to T and C always binds to G
Replication proceeds along with As, Ts, Cs and Gs being added in both a leading and lagging direction
Some cool facts about DNA replication
DNA polymerase proof-reads as it goes
There’s protein called a sliding clamp that holds the polymerase in place as it works
Topoisomerase helps the DNA from being wound too tightly as it’s pulled apart by making little nicks in the DNA to relieve the tension and then repairing them so there are no errors
The RNA primers are removed
DNA and RNA sequencing - determining the sequence of a defined piece of genetic material
Originally this was done by Sanger sequencing (think Human Genome Project)
First developed by Frederick Sanger and team in 1997
Can produced DNA sequence reads of over 500 nucleotides
So - to replicate the DNA replication process in the lab:
You combine a DNA polymerase, template DNA, a primer (remember, the short piece of DNA that binds to the template and is the starter), and the four DNA nucleotides (A,T,C,G)
And...the super special ingredients are dideoxy nucleic acids. Dideoxy meaning that the lack the “hook” to allow a new nucleotide (letter) to be added to the chain (the hook being a hyroxyl group). These nucleotides act as brakes and terminate the sequencing process when incorporated into the growing DNA strand. In a Sanger reaction they also contain a fluorescent dye (a different one for each letter/nucleotide)
The mixture is heated to separate the templates strands and then cooled and then heated again on repeat
The DNA replication process proceeds along and the ddNTPs get incorporated at random points. So you’ll end up with fragments of different lengths. These can be visualized using capillary gel electrophoresis where the different strands move a different speeds with the smallest ones going the fastest. By detecting the different colored dyes at the end (crossing line), a DNA sequence can be put together, like a puzzle where the colors and speed indicate the sequence.
Next-generation sequencing (also called massively parallel or deep sequencing)
Sanger sequence was a huge breakthrough and allowed for some monumental discoveries
Best for small numbers of genes targets and samples can be done in one day
Can take some time to do larger targets and whole genomes
NGS - analysis of multiple samples at once an different genomic features in a single run
Lower sample input
Higher accuracy
Ability to detect variants better
NGS encompasses multiple different platforms and methods
Overarching theme is the ability to sequence many strands of DNA at the same time and share a common base method
Construct a library from the sample - process DNA into relatively short fragments
Clonal amplification - each piece of DNA in the library is bound and amplified (made more of) by PCR to increase its detectability
Sequencing using various chemistries, methods and instruments
Analyze the data - these methods generate large amounts of data so bioinformatic algorithms are needed for analysis
Sequins
So you may be thinking “where in the world are we now? We started with Chanel and Valentino and ended up with DNA sequencing
We’re finally at the point to introduce the sequins - not the shiny kind, the sequencing kind. Researchers use ‘sequins’ (sequencing spike-ins) to measure technical biases and act as internal controls throughout the next generation sequencing workflow.
Human beings are infinitely complex organisms, even identical twins aren’t necessarily genetically identical, especially as they grow up. This can make analyzing sequencing data.
In addition, errors can be introduced during any of the steps we talked about in the NGS process (hey, we’re only human)
Having standardized controls (of a known sequence) allows scientists to monitor the progress of the sequencing process and mitigate potential bias.
Real-world experience:
Sequencing environmental samples to look for microbial commmunites is a preferred method for discovering microbial biodiversity since culturing samples is not only a potentially long process but yields only a fraction of the microbes in any given sample
Used to discover new microbes in the ocean, soil, etc either for benefits (pollution degraders) or health (potential pathogens)
Termed metagenomics
The size and complexity of the genomes in any given sample can make it difficult to accurately identify and quantify microbial species and we just discussed, technical biases can be introduced into the process cause we’re human.
Hardwick et al designed 86 synthetic artificial DNA sequences (sequins) to act as internal controls for environmental metagenomic sequencing
The research team took a diverse sampling of finished microbial genomes (these things are all saved in a database accessible online) that encompassed a wide range of microbial types and were isolated from a diverse range of environments
The designed sequins were synthesized and put through experiment validation and then used in a real-world metagenome experiment
They spiked the sequins in saltmarsh samples collected from a creek in Sydney’s Olympic park (the saltmarsh is part of regeneration effort). They compare three natural and three regenerated spikes
They performed the relevant analyses and found good performance indicators for the designed sequins and the additional benefit of using the sequins to normalize between samples
These sequins can be used not only as internal controls for research but also for clinical testing (think looking for a particular microbe in your intestinal microbiome)
Researchers made the sequins and associated data sets, protocols and software toolkit freely available on their website: www.sequin.xyz
I think this is really important to highlight - part of science is understanding, recognizing and mitigating any potential bias in your research, either personal, technical or otherwise. Good scientists know that they cannot be perfectly objective and so use analytical methods to reduce or deal with bias and confounding, submit themselves to peer review and repeat experiments to ensure that what they found is accurate.
Non-genomic sequin science:
That was some heavy genetic science we just navigated through. Congratulations, you made it and without the all the waiting of setting up the reactions, making sure you don’t contaminate the samples with your own DNA, waiting for the sequencing, running the analysis, etc. As a reward, here is a piece of research on the lighter side.
Belly dancing
While getting my PhD, I was introduced to the world of belly dance and immediately loved it’s body positive culture, the music, the dance, and definitely the costumes (so many sequins!!!).
In research published in the Journal of Women and Aging, Angela Moe conducted qualitative interviews with older women who belly dance and found that they not only regained mobility but also reclaimed social space and social support and redefined their relationships with their bodies.
Just a little feel-good tidbit that involves sequins and women owning the space that they should
Review
Sequencing = determining the sequence of a defined piece of genetic material
Sanger sequencing = method for one sequence at a time
NGS = sequencing of multiple sequences at a time
Nucleotides = the building blocks of genetic material (A,T,G,C for DNA)
Metagenomics = studying the collective sequences of the microbes in an environmental sample
SEQUINS - short pieces of known genetic material that is spiked into a NGS sequencing reaction to act as an internal control against technical error
Thanks for listening to this episode of LuxeSci. A very special thank you to my audio engineer, Dimos. Our theme music is Harlequin Moon by Burdy. If you have a correction, comment or praises, you can reach me at: drlex@luxesci.com. We’re on Twitter and Instagram at luxescipod and our website is luxesci.podcastpage.io. If you like us, please subscribe. Please also leave us a review where ever you listen to podcasts. See you again in 2 weeks!
Comentários