14th Xenopus International Conference - Days 1 to 3

“La biologiste passe, la grenouille reste” – Jean Rostand

Name: Gary McDowell

Date: September 9-11^th 2012

Location: Giens Peninsula, Hyères (near Toulon), France

Website: www.xenopus2012.org

Good things come but once a year, but the international Xenopus conference is so good it only comes around every other year. The conference brought together researchers from nearby Europe, further flung North America, and as far afield as Japan and New Zealand, all with one thing in common: a common love for the model organism Xenopus (that's frogs). The African claw-toed frog (a frog and not a toad, as is commonly confused) was showcased in a variety of research settings over the course of the conference, ranging from established roles in developmental biology and cell cycle research to exciting new frontiers being explored in genomics and proteomics, the study of all the genes or proteins in a cell all at the same time. The decision to set a frog conference in France was not lost on many researchers - but the absence of frog legs at the dining table was certainly appreciated.

Day 1

The Xenopus community is a small but thriving one. The use of Xenopus in geneticss has been expanded recently by the publication of the tropicalis genome and release of a laevis draft genome (the two commonly studied species of frog) significantly advancing the potential for the use of frogs in modern studies that use genetic information to study everything about an organism all together, so called ‘-omics' approaches.

At the start of the conference researchers were briefed on the progress of establishing the European Xenopus Research Centre, (EXCR, http://www.port.ac.uk/research/exrc/) in Portsmouth, UK, under the direction of Dr. Matt Guile and the National Xenopus Resource (NXR, http://www.mbl.edu/xenopus/) at Wood's Hole, MA, USA supervised by Dr. Marko Horb. These centres are designed to support researchers through supply of antibodies, plasmids and similar materials, but also to act as "research hotels" for any scientist wishing to do some frog work. Xenopus provides a very quick and useful tool to study the processes of cell division and animal growth & development. It provides a very easy to manipulate system to investigate biochemical mechanisms literally creating a "cell in a test tube". These resources are being set up to expand the opportunities for those who do not currently work with Xenopus to carry out preliminary experiments, or validate experiments carried out in other organisms.

The major event of the night was the first keynote lecture by Professor Sir John Gurdon FRS, of the Gurdon Institute at the University of Cambridge (http://www.gurdon.cam.ac.uk/gurdon.html), a prominent researcher in the field (and now recipient of the 2012 nobel prize for physiology & medicine). John Gurdon carried out some of the very first cloning experiments by nuclear transfer of nuclei from somatic cells into a frog egg to create cloned frogs, the same technique that was later used to create Dolly the sheep. In his talk he discussed recent work on nuclear reprogramming, or how a nucleus transplanted from a cell into an egg is able to "de-differentiate" into an embryonic nucleus. He contended that until we know every detail of what is happening in a single cell, at a single timepoint we won't really know what is going on inside living things. So, a lot of work is still to be done!

Day 2:

Talks on the second day began with the role of Xenopus in signaling experiments (how cells talk to each other) - most particularly, frogs are famous for their association with studying the Wnt pathway. Wnt signaling is important not only in the formation of the dorsal/ventral axis (deciding which part is the top) during embryo development but it also has a role in cancer, particularly in colorectal cancers.

Talks in the afternoon, however, focused on the role of regeneration and stem cell properties. Xenopus tadpoles have great powers of regeneration in both limb and tailbud injury and several presentations were made highlighting the often-overlooked role that Xenopus has to play in studying regenerative stem cell properties. A particularly interesting talk discussed work showing that Xenopus egg extracts are able to reprogramme certain mammalian cells into induced pluripotent stem cells; adult cells reverted into a juvenile state with the capacity to form new tissues (Ganier et al., PNAS, 2011).

The final talk of the day was a keynote lecture from Marc Kirschner, discussing the role of the frog in the post-genomic era. Work carried out by his lab in collaboration with Steve Gygi at Harvard Medical School has focused on developing Xenopus laevis as a proteomic tool. Xenopus lends itself to the study of proteins because it is easy to isolate large amounts of protein material for analysis. However, there are currently drawbacks that can limit the usefulness and ease of acquiring data using Xenopus, relating to the issues with the incomplete genome and hence a lack of basic information about proteins. A common limitation of Xenopus is the high level of genetic variation between frogs, compared to inbred lines of mice and other organisms commonly used in labs, which are almost all genetically identical and hence more consistent when used in experiments. However, Marc argued that genetic variability is actually much more useful as it more accurately reflects a natural population of animals This is arguably more relevant to making interesting new discoveries than finding highly consistent patterns in inbred lines; after all, the human population has a high level of genetic diversity itself!

Day 3:

Xenopus is a very useful organism for looking at the development of organs and tissues and day 3 kicked off with talks about the development of the lung (which occurs after the tadpole stage), kidneys and heart. A particular study related to eye development was interesting - anophthalmia ( lack of eyes) in humans - is being studied in Xenopus because it closely corresponds to the human condition.

After free time in the afternoon to sit on the beaches and absorb some heat, the talks in the evening continued on the theme of the cell cycle and cell dynamics. Many studies on ciliated cells (moving hair-like structures found on some cells) have been performed, particularly on the role of cilia motion in setting up left/right axis symmetry a key early stage in embryonic development. This session also touched upon aspects such as cell migration, particularly in formation of the neural crest (a precursor to the nervous system) and elongation of kidney tubules, as development progresses.

(Images of conference logo and John Gurdon keynote lecture provided by the author)