Why Did Nature Choose Manganese over Cobalt to Make Oxygen Photosynthetically on the Earth?

All contemporary oxygenic phototrophs─from primitive cyanobacteria to complex multicellular plants─split water using a single invariant cluster comprising MnCaO (the ) as the catalyst within photosystem II, the universal oxygenic reaction center of natural photosynthesis. This cluster is unstable outside of PSII and can be reconstituted, both in vivo and in vitro, using elemental aqueous ions and light, via photoassembly. Here, we demonstrate the first functional substitution of manganese in any oxygenic reaction center by in vitro photoassembly.

Gravitational pseudoaccommodation in patients with aphakic iris-claw intraocular lenses.

Purpose: To assess whether iris-claw intraocular lenses (IOLs) undergo gravitation-dependent changes in position and refraction.

Setting: Tertiary referral center, Bern, Switzerland.

Design: Observational case study.