Voting in the Glasgow East by-election is getting under way with polling stations open from 0700 BST.Nine candidates are contesting the Westminster seat, which was left vacant following the resignation of Labour's David Marshall on health grounds.Polling stations will close at 2200 BST with the declaration expected between 0030 and 0200 BST on Friday.Labour recorded a majority of 13,507 over the SNP in the 2005 General Election on a turnout of 48%.Voter enthusiasm is likely to play a key role in determining who wins the seat this time.Turnout could be affected by the fact the poll is taking place during Glasgow's traditional Fair holiday.