88.5 WFDD - molecular: Recent Episodes
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Signal crayfish in Lake Washington in Gene Coulon. This crayfish has several branchiobdellida annelida attached to it.
Roger Tabor
SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.
I love Cajun cooking. There’s nothing like a gumbo crawling with crawdads! While this thought may bring you back to the bayou, the Southeast – and North Carolina especially – is where it’s at if you’re a crayfish.
The center of biodiversity for crayfish is in the Southeastern United States, so we have the highest diversity of crayfishes worldwide. North Carolina itself has coming up on 50 known species of crayfishes, but there are still several in the state of North Carolina that have yet to be described, which I think is very exciting.
That’s Dr. Bronwyn Williams, Research Curator of Crustaceans at the North Carolina Museum of Natural Sciences.
In general, North Carolina is among the most biologically-diverse states, for several reasons that have previously been discussed here on SciWorks Radio.
RELATED: Diversity of Species in North Carolina
Along with that, there are a couple of thoughts as to why we we live in the the Mudbug Mecca.
You have one hypothesis: that this is the center of origin and then there was dispersal out. The other one is because they haven’t been cyclically wiped out by these huge, massive glaciers coming down and running everything off, and they have to recolonize again.
In a way, crayfish are islands unto themselves, kinda. Most species carry with them Branchiobdellida, a species of worm that live life on the clawed critter. Check them out in this video:
Dr. Williams sees the worms as an opportunity.
Can we use these species of worms to actually track or better understand the relationships among crayfish? Or interactions among crayfish?
To better understand a relatively quick, 125-mile upstream migration of a crayfish population, Dr. Williams hypothesized that the worms’ short life-cycle would give a fine-scale resolution of the migration pattern.
So, with the crayfish, we found a fair bit of variation that fit to the landscape very well, but the worms we found nothing. Everybody from Alberta to Ontario and Minnesota shared that same sequence.
Meaning there was none of the mitochondrial variation you would expect after many generations of worm reproduction.
It was just jaw-dropping. Yeah. No idea.
The crayfish host an integrated society; the worms share the neighborhood with a smaller species called ostracods, or seed shrimp.
The largest ones are about a half-a-millimeter in length, and they just look like little kidney beans with legs and antennae. As one of my interns says, they’re microscopically adorable!
Both of these groups would be what we would call obligate ectosymbionts of these crayfishes so, they are obligated to live on that host in some way, shape, or form.
Interestingly, neither the worms nor the seed shrimp actually feed on the crayfish; rather it’s the best neighborhood to raise a family.
When they lay their eggs, those embryos actually won’t develop unless they’re actually on a live crayfish, which is wacky. But nobody has been able, in a lab situation, to rear these off of a live crayfish host. So it’s some sort of uptake, some need from that live crayfish that they get to sustain those embryos.
So, you have these two completely different groups; these little arthropods, these little crustaceans and these worms, that have adopted this very similar, kind of needy lifestyle, as it were.
The highest species diversity that I’ve seen is six different species of worm on a single crayfish, and two species of these little ostracods, so eight total symbiont species on a single crayfish. And they do seem to have their own little territories for the most part. They seem to partition out. You know, “I’m going to claim between the eyes, and you’re going to go down on the tail,” and so on and so forth. They’ve got these territories worked out.
They perceive the crayfish as a landscape. You go out and log at the various buildings and the hills and so on and so forth. To them, that’s the “I’m going to plant my house here on this crayfish.”
This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of UFOmusic.com.
science #biology #crayfish #crawdads #mudbugs #north carolina museum of natural sciences #branchiobdellida #ostracods #dr. bronwyn williams #duke #dna #molecular #genes #chromosome #dr. beth sullivan
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An image of a Human Chromosome.
Zappys Technology Solutions ( https://www.flickr.com/photos/102642344@N02/ )
SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.
Do your ears stick out? What color are your eyes? Who are you?
The red is the “primary” centromere array that can be wild-type or variant, the green is the “backup” centromere. There are two chromosome 17s in the image. In the bottom 17, the primary centromere (red) is wild-type/invariant and is the one being used. In the chromosome 17 that is at the top of the image, the primary centromere (red) is extremely variant (size and sequence) and in this case, the backup centromere (green) is being used.
You are you because of a unique combination of your parents’ genes, coded into the strands of DNA molecules, coiled tightly around an “X-shaped” structure. This is a chromosome, and you have 23 pairs of them, deep down in the nucleus of all 37 trillion cells in your body.
Dr. Beth Sullivan, Associate Professor of Molecular Genetics and Microbiology at Duke University, studies chromosome rearrangements in her lab and how they may cause disease.
You can think about chromosomes as a bus, and the genes are the passengers on the bus. And those genes have to travel to a destination every 24 hours.
Each chromosome has a region where the two pairs meet. It’s filled with long and repetitive sequences that some consider to be “junk DNA.” This is called a centromere. (You can see an example in the image on the right.)
The centromere is the bus driver. So the centromere decides where the chromosome is going to go, how fast it’s going to go.
Dr, Beth Sullivan, Ph.D.
Here’s the thing…
More than half of our chromosomes have two potential bus drivers.
Or centromeres.
We wanted to understand why, and are there ever circumstances in which the bus drivers switch?
And that’s where Dr. Sullivan and her lab’s research, appearing online in the journal Genome Research, comes in.
We found that about 70% of the population “chooses” the bus driver that has the largest amount of DNA sequence, the repetitive sequence. So we call this the primary site for a centromere assembly.
Or, the “primary busdriver.”
And then we found that about 30% of the population actually form their centromere at the backup site. We wanted to understand, why would we want to use the backup driver instead of the primary driver?
They picked an important bus.
We focused on Human Chromosome 17 because it is involved in congenital defects - a lot of these are neurodegenerative diseases - and in acquired diseases like cancer. So we thought it was a good chromosome to study because if we could gain some insights into how the chromosome behaves, it would impact many areas of biomedical research.
If your primary array has a lot of sequence changes, or size changes, the smart thing for the chromosome to do is to build the centromere at the backup array. If you're in the primary array and you have no sequence or size changes, you’re good. If you're on the backup array, you’re also good because that means that the primary array was defective and you chose the backup array because it's a good place to be. But for some reason in some individuals, they don’t do this. They persist in trying to build the centromere at this variant primary array, and that array is dysfunctional.
So, if your primary bus driver is awake and alert, you’ll have a safe trip. If not, the backup driver is always ready to get you where you need to go. But, for some reason, some people have buses in all 37 trillion cells that are driven by the incapacitated primary driver, making the backup driver ride shotgun. Those buses don’t always arrive safely.
This defect is passed down from parent to child, and so Dr. Sullivan and her team may have pinpointed a cause of genetically-inherited diseases, like some forms of cancer.
The ultimate aspiration would be to completely switch the centromere location from the bad site to the backup site. But, on a more modest level, our first steps are going to be to try to use this to maybe be predictive of cancer risks.
We think that these gaps need to be filled. There’s a wealth of functional information that most people are ignoring because they consider this sequence junk, and they haven’t tried to put the puzzle pieces together to see where all these sequences fit. It’s the next frontier in genome assembly, and I personally believe that it needs to be completed so that we really understand how our genome works.
This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of UFOmusic.com.
duke #dna #molecular #biology #genes #chromosome #dr. beth sullivan
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Fish, mammal, or reptile? Reptile, but if you only had a few bone fragments, how could you tell?
Wikimedia Commons
SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem. Follow Shawn on Twitter @SCIFitz.
Dr. Elena Schroeter interviewing for SciWorks Radio at the NC Museum of Natural Sciences -Shawn C. Fitzmaurice
You are a paleontologist on expedition hunting dinosaur fossils. For all your efforts, you’ve unearthed just a few bone fragments. Back at the lab, you and your team determine that, based on their shape and size, you’re looking at a colossal waste of time and resources.
If it’s any consolation, the fact that those fossils were even there for you to find is amazing in itself. An animal has to undergo very specific circumstances after death for its bones to be essentially turned into rock. And, according to Dr. Elena Schroeter, Postdoctoral Researcher at NC State University, we don’t even fully understand how fossils are made.
There's a lot of room for discovering exactly how fossilization occurs. A lot of the time, we actually have to look at experiments that we do in real time over shorter amount of time . . .
If it were really easy for things to preserve, or if they didn't break down, then we would be buried in the bones of vertebrates past. Something interesting is already happening in a fossil that is keeping it from degrading like all of the millions and millions and millions of other bones that have ever existed. So, if that's occurring, it stands to reason that other chemical processes could be occurring that can preserve things like protein even if the chemical models we make don't predict that.
And that could be helpful to you, my unhappy paleontologist friend. In fact, protein has been found preserved in fossils up to 80 million years old! You can hear a lot about that on a past episode of SciWorks Radio.
One of the primary ways paleontologists, right now, are able to get at evolutionarily relationships is simply looking at the shape of bones. And that can be very limiting because there are a lot of things that can evolve to have similar shapes even though they're not related; things like ichthyosaur, which looks very much like a dolphin - totally unrelated, but they look very similar superficially.
With dinosaurs, some of the species will be known from really, really partial skeletons. If you can imagine having one species is known from an arm and maybe a part of the skull and another species is part of this skull and another species known for its tail and another species known from a leg, there's no way to compare all the species together.
Blood vessels from deminineralized bone of B. canadensis -NC State
But the protein being pulled from ancient dinosaur fossils (in this case collagen 1 for anyone keeping track) IS original material and can be used to help identify and classify your non-descript, formerly-disappointing bone fragments. You’ve just gone from Zero to Hero!
Proteins, because they are coded from DNA, actually do carry phylogenetic, or evolutionary, information, and you actually can get at some information about how species are related to one another simply from being able to compare protein sequences.
Like most research, Dr. Schroeter’s work has implications far beyond her lab.
There have been animals that have experienced massive climate change before, and their adaptations and responses to that would be in their molecules. If we are actually able to get more molecular data from extinct animals, we may actually be able to analyze molecular trends in response to certain climate shifts or just environmental shifts. (Learn more about climate change in deep time on this SciWorks Radio episode).
So basically what we're doing now is we're trying to get tiny amounts of preserved proteinaceous material out of rock-like fossils. So if you're looking for trace amounts of life on other planets, the techniques that we are optimizing are going to be the type of thing that you're gonna want to look at for how to analyze whether or not we're getting organic material in a different form of rock.
We're looking at the stability and the chemical degradation and changes to a protein in strange chemical environments, we might be able to say something about proteins in strange human chemical environments. So Alzheimer's actually is the inability of a protein in your brain to break down, and we're looking at proteins that, against conventional wisdom, don't break down. So, even though we are looking at something like dinosaurs - which is awesome - you can apply this in a lot of different ways outside of dinosaurs.
This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of UFOmusic.com.
science #paleontology #molecular #biology #dna #protein #dinosaurs #extra terrestrial life #climate change #alzheimer’s # elena schroeter #nc state university #north carolina museum of natural sciences #raleigh
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