T. RAJAGOPAL, A. DHIVYA, T.R. GAYATHRI, N. MURUGANANTHAM1, S. SELVARANI, P. PONMANICKAM, S. MUNIASAMY AND G. ARCHUNAN
Abstract
A low molecular mass protein (range from 17 to 20 kDa) found in urine, faeces, saliva, glandular secretions, and other pheromone sources has been discovered as a Ligand-carrier (i.e., pheromone carrier) involved in chemical-communication among mammals. The present study examines whether a low molecular protein can be found in the urine of a female Rajapalayam dog and, if so, whether its expression varies during the estrous cycle. SDS-PAGE and MALDI-TOF MS were used to detect estrus-specific urinary proteins in urine samples taken from eight female dogs. The total urinary protein level was substantially greater (p< 0.05) in the estrus phase than in the other phases. The results of SDS-PAGE analysis revealed seven different molecular masses of proteins across three phases of estrous cycle, ranging from 13 to 99 kDa. The intensity of the 17 kDa molecular mass protein was significantly higher during estrus phase and incredibly reduced during postestrus, we speculated that it may be an ovulation-indicating protein. The 17 kDa band was digested in-gel with trypsin before being analyzed using MALDI-TOF/MS and MASCOT. MALDI-TOF MS and MASCOT searches revealed the presence of MUPs (major urinary proteins) in the 17 kDa band. The present study concludes that MUPs are exclusively expressed in large amounts during the estrus phase. They might transport and prolong the longevity of volatiles in scented sites, thereby providing olfactory cues (i.e. attraction towards males). In addition, the specific expression of MUPs in Rajapalayam dog can be exploited to detect estrus.