Paul Musselman, formerly of Intel Capital and IBM's corporate development team, takes the top role at the language learning start-up.

The US-based biofuels company recruits veteran backed by Itochu Corporation recruits veteran finance director Peter Cheesbrough previously at IT consulting services company Ciber, which grew to more than $1bn revenues while he was there.

The revenue management company backed by Amazon and Hearst Corporation recruits Andrew Rutledge, whose past sales roles include posts at Google and Doubleclick.

Intel Capital-backed gaming communications company Xfire hires Malcolm Casselle, formerly key executive for Groupon's joint venture in China with Tencent,

Alexander Taub joins the US-based mobile payments business backed by employee recognition and rewards platform BetterWorks.

Marc Samwer, who headed Groupon's international operations and owns part of the company along with his brother Oliver, leaves during a torrid month for the company.

Visa-backed mobile payments service Square recruited Google Wallet co-founder Rob von Behren at the beginning of the month.

Bollywood's Salman Khan joins Intel Capital as an investor in India-based travel site Yatra.

Previously, Gray was chief executive of Nura, a privately held biotechnology company acquired by Omeros in 2006.

Repeat entrepreneur Dionne joins the molecular therapeutics company, backed by Genentech and GlaxoSmithKline's corporate venturing unit, which was founded by three academics in the field of epigenetics.