Mason Posner teaches anatomy and physiology, marine and vertebrate biology at Ashland University in Ohio. He does research on the evolution and function of the vertebrate eye lens and has interests in undergraduate research and teaching technology. He leads a Biology capstone course on science communication.
My lab topped off a great academic year with a trip to Fort Lauderdale, Florida for the ARVO vision research meeting. This was actually my first time bringing undergraduate students to this meeting. Jackie Skiba and Amy Drossman did a fantastic job presenting their research on thermal adaptation in fish lens alpha crystallins. I heard several people comment that they were impressed at the level of research being done by undergraduates at our University. Jackie and Amy really helped promote the value of undergrad research at a meeting that puts its focus on PI’s, postdocs and grad students.
This was also the second year of ARVO’s meeting blog, and my second year of contributing. This turned out to be a good way to share information from meeting veterans, and learn some new faces and names.
I recently returned from my latest class field trip to the Outer Banks of North Carolina. I am fortunate to teach an upper level marine bio course at Ashland University in Ohio. Yes, Ohio. My students can see live marine specimens in our saltwater aquarium, and lots of collected organisms from the Atlantic and Pacific coasts, but the highlight of the course is definitely our trip to North Carolina, where we stay at the Oregon Inlet campsite and make day trips up and down the coast. This is the third time I have taken my class to the OBX, and as usual we lucked out on weather. We avoided rain, had great temperatures, but did get blown out of our campsite the last night by high winds (a late night escape to my Mother’s house in Southern Shores got us some sleep before the 13 hour drive back home).
Here is a taste of our trip (thanks to my colleague Patty Saunders for serving as trip photographer). Still to come, some video and food highlights:
Our welcome to the beach after 15 hours on the road
Breaking camp the first morning
Kayaking out of Manteo harbor with the Queen Elizabeth II in the background
Official portrait on the Manteo dock
Lots of beachcombing, and a mini-study on how Oregon Inlet affects shell deposition on the beach
Beach seining yielded some small blue crabs, croaker (or spot), silverside and shrimp. The water was cold, but it was worth it.
Juvenile dolphins playing off the beach just south of Oregon Inlet
. . . and a large group of royal terns. You can see Bodie Light wrapped up in the distance while it gets a refurbished Fresnel lens (right side of picture).
Birding on Pea Island
At the top of Hatteras Light, after a great history lesson in the failures of beach stabilization by a Lighthouse volunteer
It took us almost 15 hours in our two vans to get from Ashland, Ohio to Oregon Inlet, but we had some great BBQ (Currituck BBQ) on the way and a quick stop at walmart for the camping gear we left behind. But we are here, tents are up, my students had their first trip through the dunes to the beach, and it looks like we may have fantastic weather. And with an almost new moon the stars are amazing.
More tomorrow. Must get sleep after all the driving. But I must say it is pretty cool to be posting from my iPhone in my tent next to the beach.
End of the semester teaching and a slew of chair duties have kept me away from the blog for a few weeks. But it is now 4:18 am and I am off with a colleague and 10 students for my semi-annual field trip to Oregon Inlet, North Carolina in the Outer Banks for my Marine Biology class. Look for frequent posts about our trip over the next few days.
Understanding how blood cells are formed is not only important for developing treatments against numerous diseases, but also teaches us more about the fascinating process of turning stem cells into their specialized descendants. Recent work suggests that the initial stem cell that produces all of our blood’s formed elements (cells) comes in two flavors. But how do these initial stem cells arise?
Two new studies in the journal Nature have leveraged the unique powers of the zebrafish as a model vertebrate to provide answers to this question. George Streisinger of the University of Oregon first developed this cute little pet store fish as a tool to study vertebrate development and gene function in the 1970s. It has since become a prominent player in many areas of biomedical research, and is my model of choice for studying lens development, evolution and cataract. Its use of external fertilization and a see-through egg makes it ideal for visualizing the early stages of development. And with basic molecular techniques you can make specific cell types light up with green fluorescent protein (GFP). This basic approach has now been used to provide further evidence that the initial source of blood stem cells is the lining of the aorta, the largest blood vessel leaving the heart.
Previous studies in mice suggested that hematopoietic stem cells (HSCs: which will become all types of blood cells) arise from the endothelial cells lining the ventral surface of the aorta. David Travers’ group at UCSD labelled aortic endothelial cells with GFP and used confocal microscopy to show them moving from the endothelium into the bloodstream (Movie 1). But unlike a proposed mechanism for mammals, these zebrafish HSCs do not enter the arterial bloodstream, but instead move into a neighboring vein. While this detail differs between zebrafish and mammals, Travers’ work shows that similar molecular signaling coordinates the production of the HSCs in both taxa. And in a very cool experiment, they used flow cytometry to isolate these new putative HSCs from zebrafish embryos and confirmed that they indeed became blood stem cells.
Movie 1. Live imaging of green HSCs leaving the aortic endothelium.
In the second Nature paper, Kissa and Herbomel from the Pasteur Institute in Paris used confocal microscopy to detail how new HSCs can be removed from the lining of the aorta without damaging the integrity of this tube. They document that the differentiating HSCs fold over like a burrito, bringing together the neighboring endothelial cells and joining them together before leaving the tube (Figure 1). This study also confirms that zebrafish HSCs enter the bloodstream through the neighboring vein, not the aorta, and that the process shares similar signaling to mammals. When the authors used synthetic RNA molecules called morpholinos to stop the expression of a known mammalian signaling molecule called Runx1, the movement of HSCs from the aortic lining was highly reduced.
Figure 1. Detachment of HSCs (labeled in green) from the endothelial lining of the zebrafish dorsal aorta. The arrowhead in panel F shows folding in the HSC pulling together two neighboring endothelial cells before it leaves the aorta.
So what do these papers add to our understanding of HSC generation? While the source of these cells was already thought to be the endothelial lining of the aorta, these new studies provide the first live visualization and physical description of this process. And while the physical details of the process differ between zebrafish and mammals, the molecular signaling seems to be the same, suggesting that the zebrafish can be a valuable model for further detailing the generation of HSCs and their development into blood stem cells. These studies are just one new example of the zebrafish’s growing influence in biomedical studies.
Bertrand, J., Chi, N., Santoso, B., Teng, S., Stainier, D., & Traver, D. (2010). Haematopoietic stem cells derive directly from aortic endothelium during development Nature, 464 (7285), 108-111 DOI: 10.1038/nature08738
Kissa, K., & Herbomel, P. (2010). Blood stem cells emerge from aortic endothelium by a novel type of cell transition Nature, 464 (7285), 112-115 DOI: 10.1038/nature08761
I recently purchased two Flip video cameras for my Senior Capstone biology majors to use when shooting 60 second science videos later this semester. During this past week of spring break I took it on myself to give one a shakedown cruise to see if the built in editing software would do the trick for our class.
So I present my first Flip video, edited on Flip software and annotated on YouTube. The topic is the three types of breakers found on sandy beaches – something we are talking about in my marine bio class this coming Monday. Just to entice you, there are dolphins, and my daughter says something funny at the end. Helpful comments always appreciated.
Your average anatomy and physiology textbook shows that all of the different cell types in our blood, such as the red blood cells that carry oxygen and the white blood cells that contribute to our immune system, develop from one stem cell type called a hemocytoblast (see figure below). And because of the importance of understanding the function of blood stem cells to treating many diseases, such as leukemia, this area has attracted lots of research.
A textbook description of blood cell formation.
The hemocytoblast is called a multipotent stem cell because it maintains the ability to differentiate into the different types of blood cells. This flexible stem cell “commits” to a different developmental pathway by expressing receptor proteins on its surface for different signaling molecules, that will in turn tell it what to become. The paradigm has been that there is only one type of hemocytoblast, that only becomes committed when a receptor protein is placed on the cell surface. But studies have hinted at the presence of more than one type of hemocytoblast, and a research team based at the Baylor School of Medicine has now identified two of them.
The researchers were able to identify and purify two mouse bone marrow stem cell types based on a difference in their interaction with a common cellular dye. When these purified stem cell types were transplanted into mice, the researchers found that each type preferred to make either red blood cells or immune cells. This preference was maintained in the stem cell population as each individual hemocytoblast type produced copies of itself, suggesting that the bias was programmed into the cell.
It is not known how these two stem cell types differ, or what mechanism leads to the bias in blood cell production. The researchers found that each stem cell type responded differently to a common signaling molecule used in cellular differentiation, suggesting a possible mechanism. It is possible that there may still be a homogenous population of hemocytoblast precursor cells that predates the differentiation into these two newly found subtypes. But clearly, knowing about the presence of blood stem cells with different behaviors will be important for scientists attempting to harness these cells to treat human disease. I hope to read more about it in the next edition of our textbook.
Challen, G., Boles, N., Chambers, S., & Goodell, M. (2010). Distinct Hematopoietic Stem Cell Subtypes Are Differentially Regulated by TGF-beta1 Cell Stem Cell, 6 (3), 265-278 DOI: 10.1016/j.stem.2010.02.002
I signed up for my Twitter account about two years ago, and then realized that I didn’t really want to let the world know what TV show I was watching, or what my daughter was having for breakfast. I didn’t see the use until noticing that I could follow news stories in real time, keep up with friends, and get updates from professional meetings. But it was not until I started working on this blog again recently that I realized how many scientists are using the platform to disseminate information and network with each other. Oh, and promote their blogs too.
It might just be the timing or my naiveté, but it seems like Twitter and science are in a fast growth phase. Some evidence?:
The Twitter hashtag (#) is a great way to aggregate tweets on specific topics. These hashtags are often used to make tweets from a specific meeting searchable, like the recent AAAS meeting. Dr. Isis recently started an impressive meme tagged #scienceconfessions, that became a virtual tweetup, an opportunity to meet new scientists, and incredibly funny. A must-read for all the young scientists out there so that you know what you are getting in to.
And this past weekend I had my first, prolonged, real time Twitter discussion on academic science careers. Very interesting, lots of fun, and I picked up some new followers and made a great new contact. But one worry – how do you handle the volume of messages? Now, I feel like if I am not monitoring my Twitter stream, I will miss something. Besides the blogs I try to follow, this is another set of information to keep on top of.
So, we will see how it goes. Will I keep with it? Don’t know. But I am looking forward to tweeting from the upcoming Fort Lauderdale eye meeting this May.
But the changes are more than skin deep. I have added a list in the right sidebar of my favorite posts spanning some of the different topics that I write about. And lower down in the right sidebar I have a section for Ashland science blogs. These will include blogs by student authors from our science departments, most of whom started blogging as part of my senior capstone course on science communication.
I keep reading that bloggers need a niche, a focus that sets them apart from the many wonderful science blogs that are out there. As an integrative biologist my interests span from visual ecology, vertebrate evolution and systematics to protein biochemistry and lens development. But I am also deeply involved in mentoring undergraduate research, trying various technologies in my teaching (both new and old) and have developed an interest in exciting students about their ability to communicate science on the web through blogging. Does this all equal a niche? We will see.
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