60th anniversary of “the secret of life”

Double Helix

60 years ago today, Nature published an article by Francis Crick and James Watson. It was titled, “Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid”. Finally, someone had figured out the structure of DNA. That alone was a worthy achievement, after the years of work put into it. But far more importantly, the structure suggested that DNA could be the genetic material of organisms… it could be how genetic information is passed from one cell to its daughter cells, from one organism to its offspring.

After describing how the base pairs link up in a predictable way (adenine with thymine, guanine with cytosine), the authors wrote what would become the highlight of one of the most famous academic papers of all time, and possibly one of the best examples of arrogant false modesty:

“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material”.

The rest is history. The genetic code. The Human Genome Project. Blatant sexism in science. You’ll probably be reading a lot about these as we hit the 60th anniversary of the paper. It’s a story worth revisiting, or enjoying for the first time. The work by Watson and Crick is a fantastic story because it involves scientists standing on the shoulders of giants, taking the results of other scientists’ experiments and piecing them together, and answering a huge scientific question with a simple explanation. At the same time, the story of this discovery demonstrates that scientists are people, for better or worse.

DNADouble HelixRosalindSexismWatson and Crick

The difference between homeobox and Hox genes

This is a big pet peeve. Let’s get straight to business: the terms “homeobox” and “Hox” are not interchangeable. They do mean different things. I’m correct in saying that Amphioxus (Branchiostoma lanceolatum) has 15 Hox genes. I’m also correct in pointing out that it has over 130 homeobox genes.

Gene names can be very confusing and difficult to remember, so there are many abbreviations in biology. For example, the gene insulin-like growth factor 1 is abbreviated to Igf1. Does that make it easier to remember? Who knows. But I believe the use of abbreviations is partly responsible for the incredible confusion over homeobox and Hox genes. And I do mean incredible. It’s very obviously a confusing topic for students, or anyone new to evo-devo, developmental genetics, or gene regulation… but it’s so much worse than that. Professional publications make the mistake, academics make the mistake, and they do it often. I think the reason it keeps happening is that the word “Hox” appears to be a shortened “Homeobox”. All over the internet you will see the terms used interchangeably, and sometimes with the apparently shortened version in brackets. “Homeobox (Hox)”. This otherwise decent glossary for Epigenesys manages to dump the terms homeotic, homeobox, and Hox into one single paragraph and glossary entry, which is of little help to a confused student seeking clarity. So let’s clear this up, and I’ll keep it quick.  Continue reading The difference between homeobox and Hox genes

Releasing Blue Iguanas into the wild

Many visitors to this blog arrive looking for information about the terrible conservation tragedy that occurred on Grand Cayman a few years ago, in which several rare blue iguanas were murdered It’s a sad entry, but also reminds us of the amazing work being done to breed the Blue Iguana in captivity and then release them into nature reserves.

Here’s a video of the happy part. This footage is from last year, when eight blue iguanas were released into the Salina Reserve. You can see they are left in little wooden structures. These provide shelter and security for the animal as it makes the transition from captivity to life in the Salina Reserve.

blue iguanaconservationGrand Cayman