We have arrived to the end of the summer. When we first arrived nine weeks ago I remember George saying that there was an open challenge for anyone who could directly observe the interaction of the contractile proteins actin and myosin working within the cleavage furrow of a cell dividing. The idea that something as fundamental as cell division was not fully understood really go under my skin. Life as we know it including growth and development of organisms, tissue repair, and reproduction depend on cell division. When it goes wrong you can end up with too many or too few chromosomes and its failure has been linked to cancer. George also mentioned that although our understanding of cell division has undoubtedly improved in the last few decades that there were examples from nature which are hard to explain. This could mean one of two things. Cell division is a universally conserved feature of all animal cells and our understanding of cell division is not as complete as it could be or cells have evolved different ways to use the same core components. From the beginning of this summer I have been driven by these questions George asked. Today I had the opportunity to present my findings to the wider scientific community. It was really fun to discuss my research to other scientists.
Our final posters are due this week with the poster session coming up next week. I sat down with George to analyze the data we have collected over the summer. One of the things that I love most about working in this lab is that all of our data is visual. We made several montages from movies we had taken and kymographs, a type of image we produce that shows spatial position over time in which a spatial axis represents time.
George does a lot of his image processing with ImageJ. It seems like a great program because it is free, open source, and designed for scientific images. The fact that it is open source means that people can actually write plug-ins to do specific things. A lot of scientists use it, so there are heaps of plug-ins for all kinds of processes.
This summer I have been introduced to several free, open source programs that seem to be widely used by the scientific community including Rstudio a free statistics program. Ross Whippo, a PhD student in Arron Galloway’s lab taught a workshop on using R. You can find out more about Ross, and even see the notes from the workshop he taught on this website https://rosswhippo.com/. When we have lunches with researchers one of the questions I have been asking them is “what skills are highly desired in labs?” or “what skills are highly transferable between labs and worth learning?” Over and over they have mentioned learning statistics software, especially R. They have said that many undergrads do not have much statistics and experimental design experience when they apply to graduate school and that developing those skills early is helpful when applying and when getting started actually designing graduate research.
Another program I’ve been exposed to here is QGIS. The OIMB library has offered a number of workshops this summer, in addition to a monthly journal club and a book club. A few weeks ago our library hosted Dean Walton, the science reference librarian from the University of Oregon main campus. He taught a short workshop on yet another powerful open source software called QGIS, a rival to ARCGIS the premiere geographic information systems (GIS) software. We took a 1939 aerial photograph of the area where OIMB is and georeferenced the historic photo to current satellite imagery. The first impression was of how much the area had changed, especially with the development of the marina. GIS is a wonderful tool for showing data that has a spatial component to it. This week he will be leading a workshop on photogrammetry for making 3D models of landscapes and specimens which I plan on attending.
Everyone is busy working on their posters but that does not mean we did not have enough time to celebrate the Invertebrate Ball last night. Everyone dresses up as their favorite invertebrate and walks down the catwalk. This tradition has been around for a long time and it was really fun.
If you have come along on this journey with me you will know that even though they are technically brainless, the jellyfish have continued to outsmart me all summer. The gorgon Medusa extracting her final revenge on me of all people.
I have learned several important lessons over the weeks here. Firstly, write everything down! Note taking is essential to keeping an accurate record and invaluable for going back to understand what happened during an experiment. Secondly I did not imagine research could be such a roller coaster! The ups and downs, when something starts to work and then does not, then you seem on the edge of a break though again, can be tiring. Working all day long on a problem, day after day can also be a drain, especially when nothing you do seems to work. Experimental science requires a lot of persistence and troubleshooting. That’s what makes it so challenging and rewarding at the same time.
This weekend we will be presenting our research to a general audience at the Charleston Marine Life Center. I am looking forward to this. When I went out jellyfishing today I had the aim to catch as many different species as possible. I caught at least 12 species and have prepared a wide dish with a few individuals of each. My goal is to have children look in the dish and try to see how many different kinds they can recognize. Some of the differences are quite subtle so it should make for a good observation game. I will also have eggs, planula, polyps and medusae to demonstrate the life cycle of Clytia gregaria, my main research species. And of course I will be showing the movies and images we have managed to capture of unilateral cell division in embryos.
Ps I have recently finished a book about jellyfish called Spineless: The science of jellyfish and the art of growing a backbone by Juli Berwald. It is an entertaining account of one woman’s fascination with jellyfish and an impressive summary of current research on jellyfish worldwide.
Things are starting to work a little better around here. I have switched to keeping the jellyfish in an environmental chamber so they are always at 12 degrees celsius and setting a regular feeding schedule of Artemia (brine shrimp) nauplii means the jellies are much happier and more cooperative in the lab. This means that my workflow in the lab has become more regular and I can depend on getting fertilized eggs within a certain window of time. I have even gotten some of the planula, the larval stage of the jellyfish, to settle and form hydroids, the immobile and colonial phase. See my last post for a review of jellyfish life cycles.
All of our experiments work better with fresh animals. I read today that Phialidium gregarium, “particularly during late spring and summer, this tiny jelly is so abundant as to appear to be filling the ocean.” This year, for whatever reason, this has not been the case.
Next week we will get to present our research to the public at the Charleston Marine Life Center (CMLC), a natural history museum that serves as the Oregon Institute for Marine Biology’s public outreach. It should be fun to come up with a way to show my research to a general audience. Often when I go looking for jellyfish there are families fishing or crabbing from the docks and inevitably the kids (and the adults) get curious about the jellyfish. So, I guess I’ve already started getting some practice communicating my science to non scientists.
Incredibly another week has gone by. Work in the lab coming along but not much has changed from last week. We are still working on getting conditions right for the jellyfish.
In the mean time, I thought it would be interesting for you to learn a little bit about the hydrozoan jellyfish's life cycle. There is more to it than you might know.
The life cycle of the species I am studying, Phialidium gregarium, is typical of hydrozoans. The free swimming medusa, what you think of when you think jellyfish, is the sexually reproducing phase. Individuals produce have either ovaries or testes (although this week we found a hermaphroditic individual that had two ovaries and two testes). Light cues induce the medusa send sperm and eggs into the water. Fertilization is external and the embryo develops into a small larva called a planula. Now this is where it gets interesting. After some time swimming around as a non feeding planula, the jellyfish settles down and metamorphoses into a polyp. The polyp has a stalk and tentacles around its mouth, and it somewhat resembles a tall sea anemone. The polyp reproduces asexually by cloning itself and becoming a colony of polyps. After a while the colony will produce a specialized polyps that release medusae. Once the medusa mature, the cycle starts again.
Hello again dear reader,
Another week has passed and we continue to have trouble with the jellyfish being reliable. There was however a bright glimmer of hope as we actually took our first movie of unilateral cell division in jellyfish embryos on the confocal microscope this week! This is what we have been waiting for. When we finally got the dividing cells on the microscope everyone in the lab was so excited that four of us missed lunch to watch. It was really fun (and someone saved us all a plate). The cells had been injected with ‘life act’, a probe for actin, and the movie we captured does show us some very promising features. Mostly, the famous and elusive contractile ring was nowhere to be seen. Which is interesting because if the contractile ring model is not the whole picture, how are these cells dividing? We hope to get some more jellyfish soon and try it again. Ideally we will take more videos, with probes for different things and from different angles. I knew coming into this project that it was going to be ‘exploratory’ science with no guarantee of success and I am starting to come to terms with that. At the same time, I really hope it works!
Stay tuned to see if the jellyfish come back next week
In the mean time, I'd like to introduce you to seven nudibranchs that we have found on the docks when we go down looking for jellies. Check them out! We also looked at some bryozoans and ascidians under the stereo microscopes. Both of these were types of tiny, beautiful colonial animals that you would never see if you did not look at them under a microscope.
So far the goal has been to collect wild jellyfish, and keep them on the sea tables in the lab. Then to use a recently discovered HORMONE that induces them to spawn, collect the eggs, micro inject them with RNA that will target specific parts of the cell, making them fluorescent so that we can record them under the confocal microscope.
The reason this is interesting, if just the process itself is not interesting enough, is that many jellyfish cells divide in a way that is different than other animals. The way that cells divide is only just beginning to be understood. George has been researching how a cell actually manages to coordinate its own division. What are the controls? The feedback loops? Maybe studying the mechanism in jellyfish, who essentially do it differently with the same equipment, will help us understand more about the mechanism in general.
If you know the basics of the cell cycle, then you know that cytokineses, the term for the dividing of the cell into two, normally happens in a ‘pinch’ like motion. The video below, taken by my mentor George von Dassow, shows a 'typical' cleavage pattern.
Most jellyfish on the other hand divide unilaterally, starting on one side and moving to the other in a ‘zipper’ like motion. This video, also taken by George von Dassow, shows the early divisions of Phialidium gregarium, one of the species I am working with.
So far it has been challenging to have a reliable supply of animals, as collecting them is a little boom or bust, they either are totally absent, or are there in great numbers. However, slowly but surely, I am feeling more confident knowing my way around the lab. I am getting the hang of which tides to go out looking for jellyfish, and the timing of getting them to spawn. The next important step is to successfully inject some eggs with the RNA probes and have them develop. Wish me luck!
Outside of the lab I have been enjoying the beautiful, remote Oregon coast. I have been going out surfing at Bastendorff beach. All the other REUs are really nice and we had a perfect sunny day at the beach for 4th of July with a lot of the faculty, grad students, and University of Oregon students, eating great food, playing frisbee and even swimming. Last weekend we visited the main University of Oregon campus in Eugene to meet students doing summer research there. This weekend those students will be coming up to go camping with us and we will give them a tour of our lab.
So if you are playing along from last week with 'Guess that larvae' here are the answers.
The pictures on the left are the microscopic larvae, the pictures on the right are what they become.
Drum roll please.
A) A snai! Also known as Calliostoma ligatum, commonly known as blue top snail, is a pretty little snail found in the inter tidal.
B) A sea star! Also know as Patiria miniata, or the bat star.
C) A sea urchin! Also known as Strongylocentrotus purpuratus, or the purple sea urchin.
Week 2 has been both exciting and frustrating at times. Early in the week Nina, Sadie and I met with our mentor Dr. George von Dassow to solidify our research projects. All three of us decided to take on independent projects. There is overlap, our methods will be similar, but our research subjects will be different. Nina will be continuing the work on starfish, Patiria miniata, embryos. Sadie will be working with acorn barnacle, Balanus glandula, embryos and I will be working with jellyfish. We will all be working to uncover the mysteries of life. Both of their projects are super interesting and I highly encourage the reader to check out their respective blogs to learn more about the work happening in our lab.
That’s the exciting part. The progress on my jellyfish project has been slow. We do not exactly have an established procedure for working with jellies, so I have selected three promising species to try to work with. I am attempting to find a way to reliably get gametes, particularly eggs, that we can micro inject with mRNA. We can then use a hormone that causes them to mature and add sperm to fertilize them. If we can get this to work we have a whole suite of RNA probes we can try out. Most of the probes work by making some part of the cell fluorescent. Then we will use the confocal microscope to take movies of the embryos’ early development and track the part of the cell we make fluorescent.
I am really getting a sense for the scientific process. Almost nothing I have tried this week has worked. From trying to grow food for the jellies which never hatched, to walking down to the docks to find nothing at all, to using a hormone that is supposed to induce them to spawn within an hour that actually took two hours, this has been a week of ups and downs. We’ll just have to keep at it and hope for a breakthrough.
This week I thought we could play a game of “guess that larvae!” I took the three pictures posted below, A, B and C. You tell me what common intertidal animals they come from and you win!
Answers next week.
This has been an incredible first week. Each day presents new, challenging, information and lab techniques to learn. My mentor, George von Dassow, has blown my mind several times a day. My lab mates, Nina Denne and Sadie Rose are wonderful. The very first thing we did was walk down to the ocean and catch jellyfish right off the docks. George told us about how green fluorescent protein (GFP) was originally isolated from the Aequorea victoria jellyfish that we had collected in a bucket next. The use of GFP has since transformed the field of cell biology with big implications for many fields including medicinal imaging.
Back in the lab we are learning lots about microscopy and embryology. As a way of practicing taking photographs with the microscope, I set myself the task of photographing the early embryonic stages of the purple sea urchin (Strongylocentrotus purpuratus). George recounted that he was once carrying a sea urchin from one side of the lab to the other when he got caught up in talking to someone in the hall. Without thinking about it be started to bounce the urchin up and down in his hand. To his surprise, when he looked down, it had spawned! What a happy accident! Using the now famous shake technique, I was able to get the urchin to produce eggs. Ready for use, they can be combined with sperm cells to produce zygotes. Once a sperm enters an egg the fertilization envelope develops as a block to polyspermy, the fertilization of one egg by multiple sperm.
Watching the moment of fertilization happen under the microscope blew my mind. Of course I had seen video of the event, but knowing it was happening right then, underneath my lens, was something I will never forget.
As of this writing, besides the sea urchin (Strongylocentrotus purpuratus), we have collected or fertilized embryos of a jellyfish (Aequorea victoria), a sea star (Patiria miniata), a sea snail (Calliostoma ligatum), acorn barnacles (Balanus glandula), and gooseneck barnacles (Pollicipes polymerus). I’ve also started to keep a few pets including some nudibranchs, sea cucumbers, and bioluminescent dinoflagellates. Marine invertebrates are a pretty diverse bunch!
Stay tuned next week for photographs of the continuing development of the purple sea urchin embryos. This is what they looked like at the end of this week:
Next week we will begin to define our summer research projects which will almost certainly involve working with eggs, embryos, or larvae of various invertebrates and some combination of fluorescence, time-lapse, and confocal microscopy.
See you next week!
My name is Philip Aspinall, and I am a student at Sierra College in Grass Valley, California. The first time I peered into a microscope and found an entire, complex, beautiful world below the visible, I was transfixed. I am thankful for George von Dassow and Svetlana Maslakova for allowing me to work in their lab, and to Geroge for his generosity with his time and for being my mentor this summer.