PARAFAC study of L-cys@CdTe QDs interaction to BSA, cytochrome c and trypsin: An approach through electrostatic and covalent bonds
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
Authors: Razavi, Mehri; Kompany-Zareh, Mohsen; Khoshkam, Maryam
Utilizing fluorescence spectroscopy, non-covalent and covalent interactions of L-cys@CdTe quantum dots to bo-vine serum albumin (BSA), cytochrome c and trypsin were investigated. L-cys@CdTe QDs with the emission maximum at 530 nm and an average diameter of 2.6 nm were synthesized in the aqueous medium. Formaldehyde, N(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) with N-hydroxysuccinimide (NHS), and glutaraldehyde was applied as cross-linkers. In the case of both electrostatic and covalent strategies PARAFAC, as a powerful multi-way chemometrics technique, was utilized to analyze fluorescence excitation-emission (EEM) spectra. For non-covalent and covalent bonding, two and three significant components composed the PARAFAC models. Resolved EEM shows that in the presence of formaldehyde, a new component with an emission peak similar to BSA was obtained. Using EDC-NHS cross-linker, the fluorescence peak of the newly formed component was in a distinct wavelength with similar emission intensity, compared to L-cys@CdTe QDs and BSA. Employing glutaraldehyde, a distinguished component was easily detected at emission wavelengths higher than that of L-cys@CdTe QDs and proteins. It was concluded that the choice of cross-linker is a critical step to create different emission spectra when dealing with nano-bio-conjugations. This study shows that glutaraldehyde cross-linker leads to increase sensitivity, selectivity, and accuracy of protein analysis. (C) 2020 Elsevier B.V. All rights reserved.
Dietary arginine modulates nonspecific immune responses in Indian Major Carp, Cirrhinus mrigala exposed to hypoxia
Authors: Varghese, Tincy; Kumar, V. Rejish; Gopan, Amrutha; Valappil, Rajendran Kooloth; Sajina, K. A.; Mishal, Puthiyottil; Pal, Asim Kumar
Hypoxia in aquatic environment is often a recurrent stressor which can affect growth and health of fishes. However, nutritional intervention can help aquatic animals to cope up with environmental stressors so as to alleviate the adverse effects. Here, we examined the impact of L-Arginine (Arg) supplementation on hypoxia-induced changes in immune responses and resistance to Aeromonas hydrophila infection in Indian Major Carp, Cirrhinus mrigala. The fish were fed with graded levels of Arg for 60 days and exposed to 72 h sublethal level of hypoxia (0.50 +/- 0.16 mg/L dissolved oxygen [DO]). The six treatment groups with three replicates having different levels of Arginine such as N0.0 (0% Arg + Normoxia), H0.0 (0% Arg + Hypoxia), N0.7 (0.70% Arg + Normoxia), H0.7 (0.70% Arg + Hypoxia), N1.4 (1.40% Arg + Normoxia), and H1.4 (1.40% Arg + Hypoxia) were used in the study. Subsequently, the fish of different treatment groups were challenged with A. hydrophila. The hypoxia exposed fish exhibited significantly higher (P < .05) cumulative mortality compared to the unexposed fish, while Arg-fed groups showed reduced mortality irrespective of the level of dissolved oxygen. The albumin-globulin ratio, complement-3 response, respiratory burst, myeloperoxidase, serum antiprotease and lysozyme activities were significantly lower (P < .05) in hypoxia-exposed carp, revealing the increased susceptibility of fish to A. hydrophila is due to the immunosuppressive effect of hypoxia, which was improved in Arg-supplemented groups. We conclude that there is a possible role of hypoxia in sporadic outbreaks of bacterial diseases in carps as acute hypoxia causes immunosuppression which can be reversed by 0.7% Arg supplementation.