working since 50 years ago

山中先生の続報ですが，ing形とsinceとagoが共起しているフレーズがありました。Othelloくん，こういうのは生徒にはどう説明しますか。（GP）

Japanese Nobel winner thanks assistants, family

Japanese scientist Shinya Yamanaka, 50, of Kyoto University, expressed on Tuesday his gratitude to assistants in his laboratory and family members after being awarded this year’s Nobel Prize in Medicine.
Yamanaka shares the prize with UK researcher John Gurdon, 79, of the Gurdon Institute in Cambridge, Kyodo reports.

The two scientists were rewarded for their work in the “regenerative medicine” area – the search for ways to cure disease by growing healthy tissue.

Gurdon is working in the field since 50 years ago, while Yamanaka has conducted a groundbreaking experiment in 2006, that transformed the field of regenerative medicine. He produced mouse stem cells from adult mouse skin cells by inserting a small number of genes.

His discovery demonstrated that the evolution that takes place in adult tissue could be reversed, turning adult tissue back into cells that behave like embryos.

“I strongly feel grateful and responsible,” Yamanaka said, referring to support from his assistants in the laboratory and family members that helped him continue his research.

http://www.tokyotimes.com/2012/japanese-nobel-winner-thanks-assistants-family/