Comments on: As oxygen filled the world, life’s universal clock began to tick

By: amphiox

amphiox — Thu, 17 May 2012 20:03:01 +0000

More accurately, Kaviani, molecular oxygen. It is molecular oxygen that is the reactive dangerous and energetic oxidizing agent, from which protection would be needed, and with which opportunity with respect to energetics would arise.

By: Larry Moran

Larry Moran — Thu, 17 May 2012 15:04:13 +0000

Back then, photosynthetic microbes gave off more oxygen during daylight hours, just as their modern counterparts do today (although each day was just 18 hours long since the Earth was spinning faster). Since oxygen levels rose and fell with a daily cycle, defences against free radicals worked best if they followed suit. And so, the first clocks arose from proteins that protected us from oxygen – a universal timepiece crafted by a blind watchmaker.

We’re talking about a time when all living organisms lived in the ocean. Does anyone seriously believe that the dissolved oxygen content (bicarbonate) of sea water varied significantly on an 18 hour cycle?

By: Kaviani

Kaviani — Thu, 17 May 2012 14:31:50 +0000

The Earth’s earliest days were largely free of ATMOSPHERIC oxygen. The Earth did not undergo fusion to create oxygen…it was just not O2.

By: Ed Yong

Ed Yong — Thu, 17 May 2012 12:18:27 +0000

@Thomas – I can’t speak to a connection, but it’s worth noting that the higher incidence of cancer in night-shift workers is not conclusively causal yet. On the one hand, it’s been consistently reported in a large number of studies. On the other hand, those studies have an odd habit of not controlling for important confounding factors, like economic status, and other aspects of health that could correlate with both night-shift working and cancer incidence.

By: Arch duke ferdinand II

Arch duke ferdinand II — Thu, 17 May 2012 04:43:20 +0000

What I’m wondering is how PRX protiens are linked within mammalian species. They can get rid of free radicals and communicate with cells without a feed back loop. Can they send “instrctions”

By: amphiox

amphiox — Wed, 16 May 2012 21:12:16 +0000

“These proteins had been around ever since cells have used oxygen to make energy,” says Reddy.

I suspect personally that these proteins, or at least their precursors, and the clocks they regulate, probably existed even before cells started using oxygen to make energy. There are other sources of free radicals that they could have evolved to protect against. In particular, UV light, splitting water to produce free radicals. And UV light would also rise and fall in intensity with a day-night cycle.

By: Thomas

Thomas — Wed, 16 May 2012 19:25:44 +0000

Very cool indeed. Makes me wonder if there is any relationship between this and the higher incidence of cancer reported in night-shift workers.