Harry Eastlack looked like any other baby when he was born in Philadelphia in 1933, save for an inward-turned big toe, but at age ten, he developed a swelling and stiffness in his neck and back. The group of Philadelphia doctors that treated Harry would soon discover that the soft tissues of his body including muscles and cartilage were slowly, painfully transforming into bone, twisting and fusing the young man’s body until his death at age 40. His plight is known as fibrodysplasia ossificans progressiva (FOP), and it’s caused by an autosomal dominant mutation, usually arising de novo in 2 out of every million people. In the last talk at the 2008 Society for Developmental Biology meeting in Philadelphia, Eileen Shore from the University of Pennsylvania School of Medicine talked about her work from bedside to bench with children with FOP.

After a long search over many years for a handful of families who have passed on the trait across generations, she and a group of researchers were able to link the disease to a single base substitution in a gene for a bone morphogenetic protein type I receptor called ACVR1 in 2006. In the years since, Shore and a group of collaborators has worked to define how this tiny mutation could cause such a devastating disease. In cell culture, in zebrafish, and biochemically, a picture began to emerge of a pathway that is not completely turned on but is very sensitive to a ligand. Recently Shore and colleagues have had success in engineering a mouse with the mutant gene knocked in. Though they haven’t finished developing the line, chimeras containing both the mutant gene cells and normal mouse cells have a similar inward turned big toe on their feet and are beginning to show signs of bone formation in soft tissues. Hopefully, using these chimeras, her group will be able to breed a pure line of mice with the disorder in which drugs to treat the disease can be screened and tested.

It was a stirring story and a great preparatory talk leading up to the meeting’s closing celebration at Philadelphia’s hallowed Mutter Museum at the College of Physicians of Philadelphia. Harry Eastlack decided at age 20 that he would donate his skeleton to advance research on the disease that plagued his life, and it is a centrepiece to the Mutter’s amazing exhibits. See pictures here. They’re a chilling reminder of what can happen when development goes awry.

I once had an English teacher who gave copious quizzes. Once, when someone complained about the work, he replied, “If you think my quizzes are bad you should see my testes.” It was an all-boys Catholic school, which explains how he could get away wish such crude sentiments. Nevertheless, I saw a talk about an organism that would put him and his abundant quizzes to the shame he deserves. The planarian, a flat, freshwater dwelling worm with comical eyespots and a superlative reputation for regeneration has another surprise under its belt. In addition to two ovaries just south of its tiny brain, the sexual form of some planarians has dozens of testes spread throughout its body. These are hardly exempt from the famous regenerative qualities of the planaria which can regenerate from just a tiny portion, but they grow back in ways that were interesting to the attendees at this morning’s talk on stem cells and development. Philip Newmark of the University of Illinois at Urbana-Champaign showed how when you decapitate a planarian, the testes in the body disappear as the head regrows, only once the whole animal is intact does it resume it’s production of sperm. And when starved the animals resorb the plentiful sex organs until the food returns. When Newmark’s group fed the worms bacteria engineered to produce short interfering RNAs for a specific gene called nanos, they were able to block the testes regeneration even though the animal developed fine and had no obvious defects, looking somewhat like their asexual counterparts. They’re using this model to find other genes that might be important in testes regeneration and development.

In a stem cell development talk this moring, Haifan Lin, director of the Yale Stem Cell Center showed a picture of a pie he had decorated with the letters R-N-A. What was he celebrating? Something that quite frankly frightens me.

His group has been investigating piRNAs. These are short strands of RNA, generally 30 nucleotides long in mice and a little bit shorter in Drosophila. These are similar in some ways to microRNAs and short interfering RNAs (siRNAs), but the name piRNA (literally pronounced “Pie-R-N-A”) comes from the fact that they interact with a protein called PIWI. They’re found in abundance in the testes of mice and flies and appear not only to stifle gene expression by interacting with PIWI and corresponding DNA sequences (similar to other short RNAs) but also to stabilize and promote expression (possibly similar to other short RNAs as well). Just distinguishing these elements from other short RNAs is tricky enough. The janus-like nature of piRNAs could make for a real headache. What dictates whether they turn things on or off? Then there’s abundance. Studies have counted as many as 50,000, and Lin estimates that there are as many as four times that amount. When he realilzed how long that would keep his lab busy, Lin brought in some RNA pie to celebrate (the picture looked like apple). Still he’s not completely comfortable with all the implications of his work. The testes produce thousands of different piRNAs all coming from DNA that was formerly considered junk. “Does that make the testis a genetic junkyard?” Lin asked. He quipped: “At least emotionally I have a problem with that.”

Just before a violent downpour at Philadelphia’s UPenn campus, I got to chat with Society for Developmental Biology president Eric Wieschaus of Princeton University. (An aside: His quirky sense of humour set a nice tone at the opening symposium last night. When the powerpoint presentation he was working off of broke down, he admitted “My lab doesn’t let me get too close to machines.” Later clarifying: “I’m allowed near the microscopes, just not the ones with moving parts.”). He told me he didn’t quite have the clarity of thought to offer me any overarching trends in development in general or at the meeting in particular. Indeed having been to a symposium this morning that dealt with a different organism for nearly each speaker (Amphioxus, Arabidopsis, Ascidian, Bat, Cardamine, Lamprey, Mouse, Nematode and Zebrafish, oh my!), it can be hard to pick out trends. Wieschaus was nonetheless chuffed about the quality of the talks, and the locale. Passing on the usual route of using a conference centre meant a smaller meeting for SDB. Costs for attendees may be a bit lower (student housing is available, but I’ve heard some groans about the amenities), but Weischaus says the costs for the Society end up being about the same. Ultimately it was the connection with the University of Pennsylvania community that the organizers wanted to achieve. And I’ll admit the site has quite a bit more character and charm than the sterile Pennsylvania Convention Center. Still it’s strange to have posters split between three different tiny meeting rooms on two different floors. As far as attendance, Weischaus said the site was comparable to Cancun, where the conference was held last year. As I looked to the darkening sky and reminded Weischaus that we were nearly 100 miles from the beach, he pulled back. “Well it’s less than we could fit at San Francisco.” About 750 to 800 are in attendance. I hope the rest managed to stay dryer than I did.

Most have abandoned Haeckel’s old chestnut that ontogeny recapitulates phylogeny, but when two organisms actually appear to have identical embryonic development, how close are the genetic programs that underlie each. In a wide ranging symposium on evolutionary genetics at the Society for Developmental Biology 67th annual meeting, Itai Yanai from Craig Hunter’s lab at Harvard looked at two nematode worms that are practically indistinguishable, the lab workhorse Caenorhabditis elegans and Caenorhabditis briggsae from which it diverged some 80 to 100 million years ago. Evolutionarily, that puts them about as distant as humans and mice, but morphologically they’re practically indistinguishable. So, what can Yanai say about how these organisms use those different genes during what he calls the “200 most exciting minutes in the life of the worm”? This is the time in which the worm goes from four cells to 190, and genes are turned on and off in what one would assume is a tightly controlled regulatory regimen program. Yanai constructed microarrays to look at gene expression in the two species of worm. Specifically he looked at expression of genes that are so-called one-to-one orthologs (meaning the genes look a lot alike in both organisms and haven’t been duplicated in either species since they diverged).

There are about 12,000 orthologs, and 3,500 of these gave a good profile. Of these, roughly a quarter of the genes are highly divergent in their expression. To see that much divergence during this crucial developmental period was sort of shocking, but Yanai presents some potential explanations. Shuffling of the genome, for example, could put a gene necessary for development next to one not really needed at the time. So, less necessary genes go along for the ride. It serves as a reminder that gene expression is a very rough tool for extrapolating function. Yanai noted that there’s actually quite a lot of variability in expression for different strains of C. elegans. Someone in the audience asked if that means that there’s considerable flexibility and tolerance for misexpression during development, such that there may be no canonical set of genes required. Yanai answered that to the contrary, such comparative work may help to whittle down to those genes that really are necessary. He plans to continue study in two related species of the frog Xenopus.

The opening symposium for the 67th annual Society of Developmental Biology meeting was held in the Irvine Hall on the University of Pennsylvania campus in Philadelphia. The cavernous auditorium is quite ornate with a massive pipe organ lining the front wall and arresting décor and proportions. Still more arresting was a word several slides into a talk on development and genomics by Joseph Ecker of The Salk Institue. He presented a list of ‘ome words like Proteome (cataloguing proteins), Promoterome (developing lists of DNA promoters), Phenome (cataloguing of phenotypes), Orfeome (catalogue of open reading frames), and more. But several in the hall were mumbling “What the heck is a YFome?” Before moving on to the next slide, Ecker shed some light on the mystery. Since someone invariably accuses him of missing some area of study he said, he added “Your Favourite ‘Ome.”