Sept 5 (Reuters) - Bitcoin rose 0.49% to $50,188.4 at 1004 GMT on Sunday, adding $245.24 to its previous close. The world"s biggest and best-known cryptocurrency is up 81% from this year"s low of $27,734 on Jan. 4. Ether , the coin linked to the ethereum blockchain network, rose 1.16% to $3,932.07 on Sunday, adding $44.97 to its previous close.