She’s Nerdy and Nice, she’s Dr. Ann Morris!

Dr. Ann Morris, a professor at the University of Kentucky is in Nerd Corner this week.

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CB: Describe your research interests in a nutshell (think filbert rather than brazil).

AM: I am interested in understanding the molecular mechanisms of photoreceptor development and regeneration. Photoreceptors are the light-sensing neurons in the retina, which convert the energy from photons of light into an electrical signal that ultimately gets sent via the optic nerve to the brain. Rod photoreceptors mediate dim light, or nighttime vision, whereas cone photoreceptors mediate daytime and color vision. As a developmental geneticist, I want to understand how photoreceptor cell fate is determined, and which genes are required for this process. I use zebrafish as a model genetic organism to study photoreceptor development. I also study retinal regeneration in zebrafish, because unlike mammals, these animals are capable of regenerating retinal neurons (like photoreceptors) in response to acute injury.

CB: Why do some vertebrates (e.g. the zebrafish) have the capability to regenerate and others (e.g. humans) don’t?

AM: That’s a fascinating question that has yet to be conclusively answered. There are numerous theories about why some vertebrate animals (like urodele amphibians and teleost fish) can regenerate all sorts of appendages or tissues, such as limbs, fins, retina, even heart, and others (like humans) cannot. One interesting hypothesis is that the ability to regenerate is incompatible with having an advanced adaptive immune system. Another is that regeneration is restricted in long-lived animals (like humans) to minimize the risk of tumor formation (since regeneration relies on the presence of rapidly proliferating cells). More work still needs to be done to truly understand the differences in regenerative ability we see across the animal kingdom.

CB: How will your work ultimately help cure blindness in humans?  On a fundamental level, are the fish eyes really different from our own?

Transverse section through a zebra fish retina, stained by Invitrogen

AM: Photoreceptor degeneration associated with ocular diseases such as retinitis pigmentosa (RP) and macular degeneration is a significant cause of visual impairment and blindness, for which there is currently no cure. This is because the human retina, which is part of the central nervous system, is not able to repair or regenerate neurons that have been lost to injury or disease. One promising therapeutic strategy is transplantation of healthy photoreceptor cells into the diseased retina. The new photoreceptor cells could be generated from stem cells grown in cell culture, allowing the production of large numbers of new rods and cones that upon transplantation would integrate into the patient’s retina to restore light perception. While this approach has significant potential, we are still a long way from clinical implementation of such a treatment. One of the challenges of this strategy is finding the most efficient method for producing large numbers of rods and cones from undifferentiated stem cells, because the mechanisms that regulate photoreceptor development are still poorly understood. One way to increase our understanding of how rod and cone photoreceptors are generated is to study animals which naturally possess the ability to regenerate retinal neurons following injury. If we identify genes that control photoreceptor regeneration in these animals, we may determine the best method for replacing photoreceptors in the human retina. For this reason, the zebrafish is a great model organism in which to dissect the genetic pathways that regulate photoreceptor development and regeneration.

CB: Why are the zebrafish eyes a good model system for you to use?  What other organisms’ eyes would work well for retinal research?

AM: The zebrafish is a small, freshwater fish that can be kept and bred in large numbers in the laboratory. Because the zebrafish is a vertebrate animal (like humans), the structure and types of cells found in its retina are very similar those in the human eye. Zebrafish offer several advantages for genetic and developmental studies, including robust reproduction, optical transparency of the embryo, and rapid development. Relevant to my research, zebrafish (like humans) are diurnal animals, and the zebrafish retina contains a large number of cones in addition to rods, which is advantageous for studying daytime and color vision. Although I’m quite partial to zebrafish, many other model organisms are used to study vision and retinal development, including primates, dogs, rodents, frogs, birds, and even fruit flies.

A cryosection of zebra fish retina, staining by Invitrogen

CB:  Your research makes use of a wide range of molecular and cellular techniques.  What are the most commonly used techniques in your lab, and how are they used?

AM: Some of the methods I use to study the zebrafish visual system include standard molecular and biochemical techniques to examine gene and protein expression in retinal tissue. We also use immunohistochemical methods to visualize the different cell types in the retina. One advantage of zebrafish is that we can make use of a variety of more sophisticated genetic and molecular methods such as transgenesis, forward, and reverse genetic approaches to study a gene’s function in photoreceptor development. We can also create genetic mosaics in zebrafish. This is a cool technique where we transplant cells from one zebrafish embryo at the 1000-cell stage into another embryo. We use this method to determine whether or not a genetic mutation acts autonomously (only inside the cell carrying the mutated gene) or non-cell-autonomously (has effects on neighboring cells).

CB: What’s a typical workday like for you?

AM: I wake up early and get my two children dressed and ready for school. After dropping them off, I go to work and usually spend some time in the office answering emails and writing or reading. I meet with my graduate students to discuss how their projects are coming along, and if I’m lucky I get to spend some time at the lab bench working on my own research. At some point I visit the fish room to check on the animals. Then usually I’m back in the office writing grants, reviewing, writing, or reading manuscripts, analyzing data, and preparing lectures for whichever graduate or undergraduate course I’m teaching that semester.

CB: What is your most recent publication?

AM: Alvarez-Delfin K., Morris A.C., Snelson C., Gamse J.T., Mullins M.C., and Fadool J.M. (2009) Tbx2b regulates rod versus cone photoreceptor cell fate during retinal development in zebrafish. Proc. Natl. Acad. Sci. 106(6): 2023-2028.

CB: Any advice to budding biologists?

AM: Don’t be afraid to change the focus of your research as you move from undergraduate to graduate school to postdoc. Broaden your horizons and learn new skills and techniques – you will become a much more well-rounded scientist and may be surprised at the connections you can uncover between seemingly distant fields of biology.

Fantastic Advice

CB: That really hits home with me at the moment!

CB: Do you have any non-biological talents?

AM: I speak fluent French, and I like to play the flute.

CB: If you could have 3 guests for dinner…alive or dead…who would they be?

AM: Linus Pauling, Charles Darwin, and Ricky Gervais

CB: Darwin VS Gervais…somehow I cannot think of two more different people!

CB: What would you eat?

AM: Fried shrimp!

CB: Thanks for dropping by Dr. Morris, it’s been a pleasure to have you!

Any starving botanists out there??

This week’s biology job is an excellent post-doc opportunity in a rather excellent location…

The University of the West Indies has campuses on several of the Caribbean Islands; this post-doctoral position will be based in the Republic of Trinidad and Tobago.

The Environmental Management Authority of Trinidad and Tobago has contracted the University of the West Indies to conduct a biological survey of the ASESA (the Aripo Savannas Environmentally Sensitive Area).  The ASESA is one of the first Environmentally sensitive areas to be declared in Trinidad and Tobago.. The Survey is to be carried out with the participation of the local communities around the ESA and the Forestry Division of Trinidad and Tobago, and will concentrate on the flora of the area, in particular vegetation community responses to disturbance such as fire, population dynamics of a native palm, autecology of plant species of conservation concern (3 species are recorded as endemic to the ASESA) and possibilities of propagation and ex-situ conservation of species of conservation concern.

Application details can be found here: http://sta.uwi.edu/jobs/details.asp?view=&id=647&fontSize=

Hurry!  Deadline is August 15, 2010.

Why did the toad cross the road? To get to the other side of course!

Last night I went up to Ryder Lake to check out the annual Western Toad migration. The Fraser Valley Conservancy is doing a fantastic job of making sure the tiny toadlets get across safely, with road closures in effect for most of the morning and evening during the migration.

The temperate wetlands where the western toads breed (along with red-legged frogs, Northwestern salamanders and Pacific tree frogs) are separated from their adult forest habitat by a double lane road (thanks humans). The habitat segregation results in a mass migration across the road two times during the year, pre-and post breeding. Mass migration of the newly emerged juveniles takes place over a week or so in late July, which unfortunately co-incides with peak summer traffic along the routes.

For the most part local motorists are respecting the rules, which is excellent news. Although there was still a good amount of toad-roadkill, the general consensus from Lisa Fox of the Fraser Valley Conservancy is that there is less carnage than in past years.

To witness these tiny specs hopping across the road was really incredible. At times it looked as though the entire road was moving. We had to tread very carefully to make sure that we didn’t step on any of the penny-sized toadlets at our feet! More footage of our experience will be comin’ at you in the near future, until then enjoy these beautiful photos shot by my partner in crime Matt Hawkins.