Hello, hello! This past week, our research proposals were due, meaning we all had to nail down our research questions and plan how we’ll work to answer them in the next six weeks. After a lot of thought, I’ve decided to investigate the feeding ability and morphological trade-offs of partial echinoderm larvae. When larvae are going about their lives in the ocean, they need to be able to collect food from their surroundings. Since algal cells are not particularly dense in ocean waters, it isn't efficient for larvae to just gulp up a bunch of water and filter it. Rather, they detect prey one-by-one and, ideally, capture and retain it. Central to this ability is the ciliary band – the principal feeding and swimming organ of a growing larva. In echinoderms, the ciliary band consists of a dense strip of ciliary cells that beat away from the mouth and, in response to detection of prey, produce local reversals of ciliary beat to redirect parcels of fluid toward the mouth (Strathmann 1975). Interestingly, purple sea urchins (Strongylocentrotus purpuratus) and bat stars (Patiria miniata), which have very small and large egg sizes respectively, are both able to produce functioning ciliary bands for feeding and swimming. I’m interested in understanding what happens to the ciliary band when a developing embryo loses a portion of this initial investment and must begin with a smaller starting point – will they still be able to produce a functioning ciliary band? If so, does this require other parts of the larva to compensate?
Half- and quarter-sized embryos can develop into seemingly normal larvae. But what are the impacts of this manipulation on the ciliary band? One possibility is that the larva and all of its structures, including the ciliary band, scale down equally. Another possibility is that a partial larva would instead prioritize certain structures and cells over others, leading to an altered morphology. If the latter case is true, then the larva must compensate for these disproportionate structures, losing cells from certain areas to allow for a greater number of cells in others. By fluorescently tagging areas of interest, I hope to better understand the impacts of these embryological manipulations on the structure and function of the ciliary band in echinoderms. Next week, I’ll go more into the details of my project and how exactly I’ll be investigating these questions.
In other news:
Last weekend, a few interns and I made the trip down to California to do a little hiking and camping in the Redwoods! Our hike in Jedidiah Smith State Park was absolutely breathtaking. The first half of our hike consisted of a lot of silence interspersed with exclamations of amazement as we took in the nature around us. The way back went by a lot quicker, as we were (or at least I was) more preoccupied with the thought of s’mores awaiting us back at the campsite (did I mention I love s’mores?). On Tuesday, we discussed how to make scientific posters, and half of the REUs presented their research proposals. It's so great to hear about what everyone is doing and I'm so excited to see how everyone's projects turn out.
I've decided to start a "dog spotting" portion of my blog! It will feature some of the wonderful puppers seen on and around the OIMB campus. Enjoy.
Hello and welcome back! What I’ve learned this week is that there’s really no better way to start your morning than by shaking some urchins. Seriously, try it some time. I know it seems counterintuitive to get a good grip on a spiky ball in the palm of your hand and to shake it around forcefully, but it’s actually quite a magical trick. The most common way to spawn urchins is with an injection of potassium chloride (KCl) – this stimulates the gonad wall to contract and, if you’re lucky, lots of sperm or eggs will be released. A female can release millions of eggs during each spawning, and this is way more than we’re actually able to use in one experiment. When urchins are vigorously shaken, however, they only release a portion of their gametes, allowing us to use a given animal again for future spawning. Once they’re done, we put them back in the tank and let them relax for a while.
As I gradually become more comfortable in the lab, time seems to go by more and more quickly. Last week, we started growing cultures of whole, half-, and quarter-sized sand dollar larvae in order to better understand how ciliary band and mouth proportions scale with changes in size. In order to create partial larvae, we must dissociate embryos at the 2- and 4-cell stages to form half- and quarter-sized larvae respectively. In addition, we injected one batch of embryos with GFP-centrin, allowing us to visualize ciliary band density using confocal microscopy. We have been like paparazzi or first-time moms with our little larvae, taking loads of pictures of them as they grow up.
Left: Whole-sized sand dollar larva at 9 days old (20x magnification)
Right: Half-sized sand dollar larva at 9 days old (20x magnification)
In addition to creating partial sand dollar larvae, we began manipulations with purple sea urchin (Strongylocentrotus purpuratus) embryos. At the 16-cell stage, urchin embryos have 4 small cells called micromeres. These form on one side of the embryo and are responsible for development of the skeletal rods. Sounds pretty essential, right? Well, when these cells are removed, the embryo is not necessarily doomed – other cells around it can compensate and help to form skeletal rods. Alas, the larva survives… but not without some consequences. Micromere-less urchin embryos give rise to plutei with all the right parts but with altered proportions and undersized mouths. With these tiny-mouthed larvae, we can investigate the impacts of this manipulation on prey capture.
The way we do this manipulation is, might I say, super cool. We use LASERS! We shoot embryos at the 16-cell stage with what is essentially a microscopic machine gun, taking out their micromeres and watching them explode under the microscope. It’s a great way to get out some frustration after a long day.
Left: A wonderfully intact purple urchin embryo at the 16-cell stage
Center: Two micromeres blasted, two more to go
Right: A micromere-less purple urchin embryo
Research alone has been a lot of fun, but we have had the opportunity to do a lot outside of the lab as well. Last weekend, we all went camping at Cape Arago along with students from the REU program at the main campus in Eugene. Some intense s’more making happened, and one REU may or may not have almost set his pants on fire with a flaming projectile marshmallow. On Sunday morning, we went tidepooling and I was blown away by the amazing biodiversity in the Oregon intertidal. We got to see urchin beds, nudibranchs, sea stars, anemones, sea cucumbers, crabs, and more. I have to say, tidepooling in the Pacific Northwest is really, really spectacular (sorry East Coast!).
On the fourth of July, we attended the OIMB fourth of July picnic and participated in the annual egg toss. Juan and I made it to the top four thanks to a very, very tough egg that was willing to take a few falls. That night, we got to enjoy an amazing sunset and watched fireworks from the beach by the OIMB campus. I’ll say it every week, but time here is truly flying by and I am trying to cherish every moment! Thanks for reading!
Week 2 is in the books! I’ve learned a lot in the lab in these past two weeks and have also enjoyed getting to know the other interns and hearing all about their projects. Last Saturday, we went out on the R/V Pluteus to do some dredging. Lots of fun, lots of waves, a little bit of motion sickness – but all in all an amazing day! We found a ton of cool stuff: basket stars, a variety of sea cucumbers, soft-body corals… On Sunday, Chris, Nancy, and I went on a short hike at Sunset Bay and Shore Acres State Park. It was absolutely beautiful and we couldn’t help but stop every few minutes to take pictures of the breathtaking views. We also had a professional development session this week in which we talked about research/science ethics and gave short presentations of our project proposals. Mia (Richard’s fabulous chihuahua) was a fantastic listener (see below).
We spent most of last week learning the basic techniques we’ll need to do our experiments. This week, we started jumping into our project! Kostantina and I, with lots of help from our mentor George, will be investigating adaptations of ciliated larvae for prey capture. Before a sea urchin or star fish or sand dollar can be a sea urchin or star fish or sand dollar, it needs to grow up from a tiny embryo! Between the moment an egg is first fertilized by sperm and the juvenile phase, these invertebrates must go through a larval stage. During this time, these organisms look entirely different from their future adult forms. Looking at larvae under a microscope is like looking at clouds – some look like spaceships, some like giraffes, some like astronauts… Anyways, these larvae all have something in common – they use cilia (short, hairlike projections on the surface of certain cells) to swim and eat. These cilia can be found in the form of a ciliary band, which allows larvae to create currents to transport particles of food into their mouths. Invertebrate larvae, like humans, seem to have some foods they prefer and some that they’d rather avoid. One example of this is the nemertean pilidium larva, which appears to be incredibly efficient at capturing a type of algae called cryptomonads. Cryptomonads are a particularly good source of food: they are naked, nutrient-rich, easily-digestible cells. There is one caveat, though: cryptomonads have an escape response in which they essentially shoot out a microscopic thread that allows them to rapidly jump – a useful tool when trying to escape from a predator’s mouth. However, the pilidium larva is quite successful in eating these algae, and it does so by essentially not providing any indication to the prey that it’s being eaten until it’s too late! Before they know it, the cryptomonads are trapped in the pilidium’s large and deep mouth with no means of escape.
We are interested in understanding whether big, vestibular mouths help ciliated invertebrate larvae capture cryptomonad prey. We will be manipulating embryos of sand dollars, sea urchins, and star fish in order to create larvae of different sizes and size ratios and thus various mouth sizes. High-speed video will be used to determine whether it’s easier for prey to escape from small mouths, and confocal microscopy will be used to understand the impacts of our manipulations on larval proportions and the ciliary band. This week, we started a few cultures of half- and quarter-size sand dollar larvae, and we’ve been documenting their development using a compound microscope. In later weeks, I’ll get more into the nitty-gritty of the techniques we’re using! Thanks for reading!
If you had told me a few years ago that I’d be studying marine biology, I probably wouldn’t have believed you. The ocean and all of the fascinating and unique life within it were not on my mind as I entered college with a plan to pursue a career in medicine. I began this plan by majoring in music while taking the courses necessary to apply to medical school: biology, general chemistry, organic chemistry, psychology… But when I finished my first year of college, I wasn’t satisfied – I wanted to understand, like really understand, the topics I had covered in those introductory biology courses. I wanted to know why and how things happened. I wanted to make more sense of the topics we had only just glossed over in that one year. I wanted to fall down the endless rabbit hole that is biology and to explore questions that didn’t necessarily have answers. I realized I wanted to embark on a journey of exploration and discovery in the sciences, continuously learning and trying to better understand the world around me.
I joined a marine organismal biology lab in my second year of college and discovered a field of study that I had never imagined myself in. I am so thankful for the unexpected opportunities that sometimes arise in life, because I couldn’t imagine myself doing anything else today. Whenever I’m not thinking about the ocean or science, I enjoy playing piano and bassoon, listening to podcasts, hiking, baking, eating ice cream (Moose Tracks especially), and hanging out with my dog and cats.
This summer, I feel so lucky to be a part of the REU program here at OIMB and to have the opportunity to be immersed in research for an entire summer. I applied to the program because I wanted the opportunity to dedicate all of my time and energy to research and to spend an entire summer at a marine field station. As of right now, I am hoping to pursue a PhD in marine biology in the future, so the opportunity to work on my own project and to participate in professional development workshops is so valuable. This summer, I am working under the mentorship of George von Dassow, and I have already learned so much in just this first week. We spent the past few days learning some basic techniques that we’ll need for our projects, including microinjections and how to spawn, fertilize, and care for the various animals we will be working with. Alongside fellow REU Kostantina, I will likely be working on a project related to ciliated larvae and their adaptations for prey capture. I am looking forward to the rest of the summer and to seeing where my project takes me, and I hope this experience doesn’t go by too quickly!
Hello! My name is Ana and I am a rising senior studying biology and music at the College of the Holy Cross in Worcester, Massachusetts. This summer, I am working under the mentorship of George von Dassow. I am looking forward to seeing where my research takes me and to becoming a part of the OIMB community!