“I only ask to be free. The butterflies are free,” wrote Charles Dickens in Bleak House. So too are the two papers about the circadian clock of the monarch butterfly (Danaus plexippus) by Steven Reppert and colleagues at the University of Massachusetts Medical School, published this week in PLoS Biology [1] and PLoS ONE [2]; the full text of both articles – and all of the articles PLoS publishes – is freely available online.

In “Cryptochromes Define a Novel Circadian Clock Mechanism in Monarch Butterflies That May Underlie Sun Compass Navigation [3],” published in PLoS Biology, Reppert and colleagues reveal that the circadian clock of the monarch uses a novel molecular mechanism, heretofore not found in any other insect or mammal.

In “Chasing Migration Genes: A Brain Expressed Sequence Tag Resource for Summer and Migratory Monarch Butterflies (Danaus plexippus) [4],” published in PLoS ONE, meanwhile, the researchers describe a brain expressed sequence tag resource, used to identify genes involved in migratory behaviours by comparing the gene expression in the brains of migrating butterflies to those of non-migrating butterflies

The story was picked up by the Associated Press (Inner Clock May Lead Monarch Butterflies [5]) and, as such, currently has 128 hits on Google News [6]. Some of the other coverage of the story included:

• The Daily Telegraph, UK: Monarch butterflies use human clock to migrate [7]
• Science: The Sun Is My Guide, Quoth the Butterfly [8]
• Toronto Star: Monarch's map to Mexico [9]
• Science Daily: Molecular Basis Of Monarch Butterfly Migration Discovered [10]
• Scientist Live: Flight of the Monarch Butterfly [11]
• People’s Daily Online, China: How monarch butterflies fix bearing in long flight? [12]
• Medical News Today: The Monarch Butterfly Migration: Model For The Study Of Neural Processes [13]
• Daily Green: Scientists Unlock Secret to Monarch Migration [14]
• Calgary Herald: Butterfly brains could hold clues to human illnesses [15]

There has been quite a lot of interest in the blogosphere too: check out Bora Zivkovic [16]’s post Clocks and Migratory Orientation in Monarch Butterflies [17], as well as The Butterfly Clock [18] at Idiosynchrony [19] and The monarch’s inbuilt solar compass [20] at 12 Degrees of Freedom [21].

While on the subject of six-legged monarchs, one of the 22 other papers published in PLoS ONE this week was “Self Assessment in Insects: Honeybee Queens Know their Own Strength [22]” in which the authors studied strategic decisions made by honeybee queens in fights for reproductive dominance. Why not fly over to PLoS [23] to read the studies behind the media buzz?