We investigate the degree to which the environment affects the evolution of galaxies in clusters. One way is to study the fate of gas in cluster galaxies by deep HI synthesis imaging. We are interested in the correlation between HI deficiency of galaxies and the dynamical states of clusters/the richness of intracluster medium. Another way is to model the environmentally induced physical mechanisms such as ram-pressure stripping/compression, galaxy harassment and tidal heating in the context of a semi-analytic model of galaxy formation (van Kampen, Jimenez, &\ Peacock 1999). The evolutionary trends in, for example, HI, colour, morphology and SFR can be predicted with our model to be compared with our HI observations and other multi-wavelength observations. Preliminary results on an HI observation of Abell 85 and the modeling will be presented.