When Genteric Inc. in Alameda declared bankruptcy last month, the 7-year-old company revealed plans to abandon a 32,000-square-foot lab facility it developed just three years ago. Ditto for South San Francisco’s Deltagen Inc., which went bankrupt in 2003 after building a more than 100,000-square-foot facility in Redwood City. Signature BioScience Inc. left its building at Campus Bay Research Park in Richmond for new digs in San Francisco in 2002 and soon thereafter closed its doors. The Richmond building remains largely vacant. Kosan Biosciences Inc. in Hayward reportedly is looking to move to South San Francisco, where Pfizer is subleasing space it inherited when it merged with Pharmacia, which previously bought Sugen Inc. And so it goes for the boom-and-bust life sciences industry. A game of musical chairs plays out among biotech and medical device companies looking for spaces to fit their growing - and sometimes shrinking - needs. For the past few years, many of those chairs have remained empty. But some brokers and developers say they’ve begun to see nascent signs of improvement.