Science
- Drosophila brain: connectivity in the first instar larval brain
- Planarians: the embryonic development of Schmidtea polychroa
- Protocols
- Reading notes
Drosophila brain: connectivity in the first instar larval brain
My current occupation. Why I am working with fruit flies? It's mostly about a person, a man, a professor at UCLA. His name is Volker Hartenstein. His enthusiasm can move mountains. His students are usually well-natured and just love what they do. He manages to attract this kind. I came to Los Angeles blindly, looking for help in my planarian research for my PhD. What I found was someone from which I could learn the profession of scientist.
Over the years the Hartenstein's lab has gathered considerable knowledge on the celullar and molecular details of fly brains. In his lab, there is unique knowledge in the anatomy of and gene expression patterns in the embryonic and larval brains which is nowhere else to be found.
Fly brains are beautiful. Bilaterally symmetric, sleek and extremely ordered. From fly to fly one can identify the same exact neurons, the same exact projections. And track them over larval and pupal developmental stages. Such properties make the fly brain amenable to genetic dissection, using mutants, and bring feasibility to the idea of mapping all brain axons and dendrites.
My specific focus: the microcircuitry within the brain neuropile, and the descending and ascending projections to and from the ventral nerve cord. About the former, my colleagues at the Max Plank Institute for Molecular Cell Biology and Genetics are hosting 400 TEM serial sections of the first instar neuropile that I imaged there on Fall 2006 in Pavel Tomancak's group [1]. I have a couple hundred more sections acquired at the the Automated Molecular Imaging group in San Diego, using Leginon, still unreleased. Of course the whole 600 gigabyte dataset is viewed, modeled and annotated using TrakEM2, and rendered in Blender.
[1] Special thanks to Quentin De Robillard (TEM help and excellent rock climbing partner), Stephan Preibisch (FFT king of image registration) and Stephan Saalfeld (kick-ass web viewer).
Planarians: the embryonic development of Schmidtea polychroa
My PhD Thesis was a journey of discovery into the egg capsule of planarians, by the hand of Rafael Romero (University of Barcelona) and Volker Hartenstein (UCLA). Planarians, least you don't know it, are fascinating non-parasitic slimy little flatworms with an idiosyncratic embryonic development. Reference papers dated from the early XX century, plus a dozen published between the fifties and early seventies. My thesis work was to bring triclad embryonic development to the molecular era, and study the relationships between embryogenesis and regeneration.
Given the staggering lack of literature and the non-standardness of the model, planarians are rather hard to work with. Below I have collected three figures from my PhD Thesis which may help you in the hard task of identifying developmental stages of planarian embryos when dissected (left), in raw paraffin sections (center) and in epon, methylene blue-counterstained sections (right). The species in particular is Schmidtea polychroa.
Protocols
- Electron microscopy: how to fix, dehydrate and embed fly brains for optimal sectioning [ PDF ].
- In situ hybridization on paraffin sections of planarian embryos. See the technical paper [ PDF ].
Reading notes
I have collected some of my reading notes mostly from scientific papers involving insect brains and neuroscience in general, but also from a few websites and math and computer science books.