Hydrodynamic interaction at micrometer scale has noticeable similarity with Coulomb interaction. Both of them are long ranged and are of great importance in understanding of functions and structures of biological systems at cellular level. Here I will talk about a few examples of interesting phenomena occurring in a system consisting of extended objects strongly coupled through hydrodynamic or Coulomb interaction. Firstly, the dynamics of micro-objects, far from equilibrium, in hydrodynamic medium such as ciliary propulsion using hydrodynamic synchronization and chiral molecule separation using shear flow will be discussed. In the latter half of this talk, I will discuss condensation of charged biopolymers, which is in fact surprising and puzzling phenomena in sharp contrast with the common sense that like charges always repel. For example, DNA is a highly, negatively charged biopolymer, but these likely-charged DNA usually form strongly condensed phases. DNA condensations are effectively driven by short stiff polyamines such as spermine and spermidine. A recent progress explaining the prevailing role of polyamines on the charged biopolymer condensation will be presented.