Exploration of salivary proteins in buffalo: an approach to find marker proteins for estrus.

Saliva is considered as the best source of biological material for biomarker discovery studies since it is noninvasive in comparison to other body sources. Usually buffalo cannot precisely express estrus signals. Hence, there is a need for concise methods to detect the time of estrus to ensure the success of artificial insemination. Therefore, we have established a reference proteome map on the whole saliva of buffalo during their estrous cycle with special reference to estrus. Nearly 12 bands have been observed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole saliva. Collectively, 179 proteins are identified with respect to different phases of the estrous cycle using mass spectrometry. On the whole, 37 proteins are exclusively expressed in the estrus phase, which include ß-enolase, Toll-like receptor (TLR) 4, clusterin, lactoperoxidase, serotransferrin, TGM3, UBA6, and transducin. Among the proteins, ß-enolase and TLR 4 were validated, and their specific expression was found during estrus as compared to other phases using immunoblot. The functional annotation reveals many as binding proteins in the estrus saliva when compared to the other phases. The present findings conclude that the proteomic approach adopted to identify the proteins from buffalo saliva around the estrous cycle may provide a new tool for screening the estrus phase. The results further conclude that the specific expression of ß-enolase and TLR 4 can be taken as the indicator of estrus in buffalo.

Evaluating the binding efficiency of pheromone binding protein with its natural ligand using molecular docking and fluorescence analysis.

Chemosignals play a crucial role in social and sexual communication among inter- and intra-species. Chemical cues are bound with protein that is present in the pheromones irrespective of sex are commonly called as pheromone binding protein (PBP). In rats, the pheromone compounds are bound with low molecular lipocalin protein α2u-globulin (α2u). We reported farnesol is a natural endogenous ligand (compound) present in rat preputial gland as a bound volatile compound. In the present study, an attempt has been made through computational method to evaluating the binding efficiency of α2u with the natural ligand (farnesol) and standard fluorescent molecule (2-naphthol). The docking analysis revealed that the binding energy of farnesol and 2-naphthol was almost equal and likely to share some binding pocket of protein. Further, to extrapolate the results generated through computational approach, the α2u protein was purified and subjected to fluorescence titration and binding assay. The results showed that the farnesol is replaced by 2-naphthol with high hydrophobicity of TYR120 in binding sites of α2u providing an acceptable dissociation constant indicating the binding efficiency of α2u. The obtained results are in corroboration with the data made through computational approach.

Buffalo cervico-vaginal fluid proteomics with special reference to estrous cycle: heat shock protein (HSP)-70 appears to be an estrus indicator.

Cervico-vaginal fluid (CVF) plays significant roles in coitus, sperm transport, and implantation. It is believed to be a good noninvasive biomarker for various diagnostic purposes. In this study, a comprehensive proteomic analysis of buffalo CVF was performed during the estrous cycle in order to document the protein expressions, utilizing SDS-PAGE, mass spectrometry, and immunoblot. The main objective was to screen the CVF of buffalo for one or more estrus-specific proteins. A total of 416 proteins were identified in the CVF of both estrus and diestrus phases. Out of these proteins, 68 estrus-specific proteins have been extensively reviewed in the protein database. The major physiological functions of estrus CVF proteins appeared to be stress response, immune response, and metabolic. Eventually, the expression level of heat shock protein-70 in the CVF during the estrus phase, as revealed in SDS-PAGE analysis, was higher than during diestrus. The identity of the protein was confirmed by immunoblot analysis as heat shock protein-70. The findings provide a potential lead for the evaluation of these proteins for estrus detection in buffalo because CVF biomarker detection is a noninvasive technique. The mass spectrometric data of identified proteins have been deposited at the ProteomeXchange with the identifier PXD000620.

Primary structural documentation of the major urinary protein of the Indian commensal rat (Rattus rattus) using a proteomic platform.

PURPOSE: A number of proteome studies have been performed recently to identify pheromone-related protein expression and their molecular function using genetically modified rodents' urine. However, no such studies have used Indian commensal rodents; interestingly, in a previous investigation, we confirmed the presence of volatile molecules in commensal rodents urine and these molecules seem to be actively involved in pheromonal communication. Therefore, the present study aims to identify the major urinary protein [MUP] present in commensal rat urine, which will help us to understand the protein's expression pattern and intrinsic properties among the rodents globally. EXPERIMENTAL DESIGN: Initially, the total urinary proteins were separated by 1-D and 2-D electrophoresis and then subsequently analyzed by Matrix Assisted Laser Desorption Ionization-Time of Flight and Mass Spectrometer (MALDI-TOF/MS). Furthermore, they were then fragmented with the aid of a Tandem Mass Spectrometer (TOF/TOF) and the identified sequences aligned and confirmed using similarity with the deduced primary structures of members of the lipocalin superfamily. RESULTS: The SDS-PAGE protein profiles showed distinct proteins with molecular masses of 15, 22.4, 25, 28, 42, 50, 55, 68, and 91 kDa. Of these proteins, the 22.4 kDa protein was considered to be target candidate. When 2D elctrophoresis was carried out, about approximately 50 spots were detected with different masses and various pI ranges. The 22.4 kDa protein was found to have a pI of about 4.9.This 22.4 kDa protein spot was digested and subjected to mass spectrometry; it was identified as rat MUP. The fragmented peptides from the rat MUP at 935, 1026, 1192, and 1303 m/z were further fragmented with the aid of MS/MS and generated de novo sequence and this confirmed this protein to be the MUP present in the urine of commensal rats. CONCLUSION: The present investigation confirms the presence of MUP with a molecular mass of 22.4 kDa in the urine of commensal rats. This protein may be involved in the binding of volatile molecules and opens up a discussion about how volatile and non-volatile molecules in the commensal rats' urine may contribute chemo-communication.