Dmitriy Shipilov seized soon after publication of interview with advocate of greater Siberian autonomy.
'Monstration' leader detained by police special forces.
Calls for 'federalisation' are a threat to country's 'constitutional order, territorial integrity and sovereignty'.
May Day saw around 3,000 'monstrators' out on the streets of Novosibirsk, the latest gathering of a trend that began in 2004.
Anna Tereshkova unveils her ambitious plans to break old taboos and make Novosibirsk a capital of modern art.