Systems Network Analysis of Protein Interaction Network (PIN) for deducing molecular mechanistic action of BaP induced carcinogenesis

Background: Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon, has been placed in group 1 by IARC which indicates that it is a potential carcinogen to human beings. It has shown tumorigenic properties in approximately all animal model systems. In the current study, we have tried to identify the most probable biomolecular targets of BaP using systems biology approach. Method: All the proteins that interact with BaP were extracted from T3DB. STRING-db was used to generate the Protein- protein interaction network (PPIN). Various apps of cytoscape software were used for network analysis, modulation and GO enrichment analysis. By developing biokinetic models, we then tried to find the impact of BaP on the top three most probable biomolecular targets and how whole of the cell cycle is getting perturbed which may ultimately lead to carcinogenesis. Apart from this, in this study we have also tried to propose a hypothesis of removing BaP from the cell vicinity by exploiting the scavenging properties of carbon based nanoparticles using in silico approach. Result: 4000 genes were extracted from T3DB for which network was generated. On network analysis, 2058 nodes were obtained that were connected by 13850 edges. MCODE created 65 clusters which had 411 seed proteins and enrichment analysis showed that most of the proteins present in the network participate in cell cycle regulatory pathways. On molecular docking analysis QSOX1, PTGS2 and NOS2 emerged out to be top three most probable biomolecular targets of BaP out of which PTGS2 is directly involved in cell cycle regulatory pathways. Biomolecular kinetics showed that when PTGS2 gets hampered by BaP, cell cycle regulation gets disturbed and cell may become cancerous. On in silico analysis of the scavenging potential of carbon based nanoparticles, BaP showed higher binding efficiencies for SWCNT and MWCNT as compared with QSOX1. Conclusion: Based on the in silico docking results we can hypothesize that carbon based nanoparticles can be used to scavenge BaP molecules from the cell vicinity

Photometric Metallicity and Distance for the Two RR Lyrae in Segue II and Ursa Major II Dwarf Galaxies Based on Multi-Band Light-Curves

Multi-band light curves of two RR Lyrae variables in Segue II and Ursa Major II ultra-faint dwarf (UFD) galaxies were collected from near simultaneous observations using the Lulin One-meter Telescope in Vgri bands. Together with Gaia G-band light curves, we determined photometric metallicities using empirical relations involving pulsation period and Fourier parameter as dependent parameters. We demonstrated that the RR Lyrae photometric metallicity can be determined accurately when these empirical relations were employed at multiple wavelengths, which can potentially improve the distance determination based on RR Lyrae stars. The photometric metallicities based on our approach were found to be $-2.27\pm0.13$ dex and $-1.87\pm0.16$ dex for the RR Lyrae in Segue II and Ursa Major II UFD, respectively, with corresponding distance moduli of $17.69\pm0.15$ mag and $17.58\pm0.15$ mag, in agreement with previous literature determinations. This approach of photometric metallicity of RR Lyrae based on multi-band optical light curves will be particularly relevant for distance measurements in the era of the Vera C Rubin's Legacy Survey of Space and Time.Comment: 9 pages, 3 figures and 5 tables, AJ accepte

Light Curve Parameters of Cepheid and RR Lyrae Variables at Multiple Wavelengths −- Models vs. Observations

We present results from a comparative study of light curves of Cepheid and RR Lyrae stars in the Galaxy and the Magellanic Clouds with their theoretical models generated from the stellar pulsation codes. Fourier decomposition method is used to analyse the theoretical and the observed light curves at multiple wavelengths. In case of RR Lyrae stars, the amplitude and Fourier parameters from the models are consistent with observations in most period bins except for low metal-abundances ($Z<0.004$). In case of Cepheid variables, we observe a greater offset between models and observations for both the amplitude and Fourier parameters. The theoretical amplitude parameters are typically larger than those from observations, except close to the period of $10$ days. We find that these discrepancies between models and observations can be reduced if a higher convective efficiency is adopted in the pulsation codes. Our results suggest that a quantitative comparison of light curve structure is very useful to provide constraints for the input physics to the stellar pulsation models.Comment: 8 pages, 6 figures. To appear in "Proceedings of the 2nd Belgo-Indian Network for Astronomy & Astrophysics (BINA) workshop, held in Brussels (Belgium), 9-12 October 2018

On the Variation of Fourier Parameters for Galactic and LMC Cepheids at Optical, Near-Infrared and Mid-Infrared Wavelengths

We present a light curve analysis of fundamental-mode Galactic and Large Magellanic Cloud (LMC) Cepheids based on the Fourier decomposition technique. We have compiled light curve data for Galactic and LMC Cepheids in optical ({\it VI}), near-infrared ({\it JHK}$_s$) and mid-infrared (3.6 $\&$ 4.5-$\mu$m) bands from the literature and determined the variation of their Fourier parameters as a function of period and wavelength. We observed a decrease in Fourier amplitude parameters and an increase in Fourier phase parameters with increasing wavelengths at a given period. We also found a decrease in the skewness and acuteness parameters as a function of wavelength at a fixed period. We applied a binning method to analyze the progression of the mean Fourier parameters with period and wavelength. We found that for periods longer than about 20 days, the values of the Fourier amplitude parameters increase sharply for shorter wavelengths as compared to wavelengths longer than the $J$-band. We observed the variation of the Hertzsprung progression with wavelength. The central period of the Hertzsprung progression was found to increase with wavelength in the case of the Fourier amplitude parameters and decrease with increasing wavelength in the case of phase parameters. We also observed a small variation of the central period of the progression between the Galaxy and LMC, presumably related to metallicity effects. These results will provide useful constraints for stellar pulsation codes that incorporate stellar atmosphere models to produce Cepheid light curves in various bands.Comment: 22 pages, 19 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa