Background. Most human hairs collected at old crime scenes do not contain nuclear DNA and are therefore of less value for forensic investigations. In the present study, hair shaft proteins were extracted from 40 healthy subjects between the ages of 21 to 40 years and profiled using gel electrophoresis-based proteomics to determine if they can be used to distinguish gender and ethnicity. Methods. Extraction of the human hair shaft proteins was performed using a newly developed alkaline solubilisation method. The extracts were profiled by 2-dimensional electrophoresis and resolved protein spots were identified by mass spectrometry and queried against the human hair database. The study was then followed-up by immunoblotting of the identified hair shaft keratin of interest using commercially available antibodies. Results. Separation of the human hair shaft proteins by 2-dimensional electrophoresis generated improved and highly resolved profiles. Comparing the hair shaft protein profiles of 10 female with 10 male subjects and their identification by mass spectrometry and query of the human hair database showed significant altered abundance of truncated/processed type-II keratin peptides K81 (two spots), K83 (one spot) and K86 (three spots). The 2-dimensional electrophoresis profiling of 30 hair shaft samples taken from women of similar age range but from three distinctive ethnic subpopulations in Malaysia further showed significant altered abundance of one type-I and four type-II truncated/processed keratin peptides including K33b, K81, K83 and K86 (2 spots) between at least two of the ethnic groups. When a followed-up immunoblotting experiment was performed to detect the relative expression of the K86 peptides using commercialised antibodies, similar trends of expression were obtained. The present data, when taken together, demonstrated the potential use of keratin peptide signatures of the human hair shaft to distinguish gender and ethnicity although this needs to be further substantiated in a larger scale study.How to cite this article Mohamed Nasir N, Hiji J, Jayapalan JJ, Hashim OH. 2020. Potential use of human hair shaft keratin peptide signatures to distinguish gender and ethnicity. PeerJ 8:e8248 http://doi.org/10.7717/peerj.8248 Smith TA, Parry DAD. 2007. Sequence analyses of Type I and Type II chains in human hair and epithelial keratin intermediate filaments: promiscuous obligate heterodimers, Type II template for molecule formation and a rationale for heterodirner formation. Journal of Structural Biology MJ. 2000. A modified silver staining protocol for visualization of proteins compatible with matrix-assisted laser desorption/ionization and electrospray ionization-mass spectrometry. Electrophoresis 21:3666-3672.

The circadian clock regulates vital aspects of physiology including protein synthesis and oxidative stress response. In this investigation, we performed a proteome-wide scrutiny of rhythmic protein accrual in Drosophila melanogaster on exposure to rotenone, rotenone + hesperidin and hesperidin in D. melanogaster. Total protein from fly samples collected at 6 h intervals over the 24 h period was subjected to two-dimensional gel electrophoresis and mass spectrometry. Bioinformatics tool, Protein ANalysis THrough Evolutionary Relationships classification system was used to the determine the biological processes of the proteins of altered abundance. Conspicuous variations in the proteome (151 proteins) of the flies exposed to oxidative stress (by rotenone treatment) and after alleviating oxidative stress (by hesperidin treatment) were observed during the 24 h cycle. Significantly altered levels of abundance of a wide variety of proteins under oxidative stress (rotenone treatment) and under alleviation of oxidative stress (rotenone + hesperidin treatment) and hesperidin (alone) treatment were observed. These proteins are involved in metabolism, muscle activity, heat shock response, redox homeostasis, protein synthesis/folding/degradation, development, ion-channel/cellular transport, and gustatory and olfactory function of the flies. Our data indicates that