The slides for microscopy were prepared as described in Dajkovic et al.,(2008)with slight modifications. After wiping the glass slide with ethanol, 200μL of 1% molten agarose was layered on it between two strips of tape and clean cover-slip placed on it to obtain levelled surface. The agarose was allowed to solidify and the cover-slip was carefully removed and5μlof sample was put on top of the agarose and carefully covered with a cover-slip