Regulation at the level of translation in eukaryotes is feasible because of the longer lifetime of eukaryotic mRNAs in the cell. The elongation stage of mRNA translation requires a substantial amount of energy and also eukaryotic elongation factors (eEFs). The important component of eEFs, i.e. eEF2 promotes the GTP-dependent translocation of the nascent protein chain from the A-site to the P-site of the ribosome. Mostly the eEF2 is regulated by phosphorylation and dephosphorylation by a specific kinase known as eEF2 kinase, which itself is up-regulated by various mechanisms in the eukaryotic cell. The activity of this kinase is dependent on calcium ions and calmodulin. Recently it has been shown that the activity of eEF2 kinase is regulated by MAP kinase signalling and mTOR signalling pathway. There are also various stimuli that control the peptide chain elongation in eukaryotic cell; some stimuli inhibit and some activate eEF2. These reports provide the mechanisms by which cells likely serve to slow down protein synthesis and conserve energy under nutrient deprived conditions via regulation of eEF2. The regulation via eEF2 has also been seen in mammary tissue of lactating cows, suggesting that eEF2 may be a limiting factor in milk protein synthesis. Regulation at this level provides the molecular understanding about the control of protein translocation reactions in eukaryotes, which is critical for numerous biological phenomenons. Further the elongation factors could be potential targets for regulation of protein synthesis like milk protein synthesis and hence probably its foreseeable application to synthetic biology.

Heat shock proteins are ubiquitously expressed intracellular proteins and act as molecular chaperones in processes like protein folding and protein trafficking between different intracellular compartments. They are induced during stress conditions like oxidative stress, nutritional deficiencies and radiation. They are released into extracellular compartment during necrosis. However, recent research findings highlights that, they are not solely present in cytoplasm, but also released into extracellular compartment during normal conditions and even in the absence of necrosis. When present in extracellular compartment, they have been shown to perform various functions like antigen presentation, intercellular signaling and induction of pro-inflammatory cytokines. Heat shock proteins represents as dominant microbial antigens during infection. The phylogenetic similarity between prokaryotic and eukaryotic heat shock proteins has led to proposition that, microbial heat shock proteins can induce self reactivity to host heat shock proteins and result in autoimmune diseases. The self-reactivity of heat shock proteins protects host against disease by controlling induction and release of pro-inflammatory cytokines. However, antibodies to self heat shock proteins haven been implicated in pathogenesis of autoimmune diseases like arthritis and atherosclerosis. Some heat shock proteins are potent inducers of innate and adaptive immunity. They activate dendritic cells and natural killer cells through toll-like receptors, CD14 and CD91. They play an important role in MHC-antigen processing and presentation. These immune effector functions of heat shock proteins are being exploited them as therapeutic agents as well as therapeutic targets for various infectious diseases and cancers.

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The present study has examined the effect of different concentrations (1 μg/ml, 10 μg/ml and 100 μg/ml) of titanium oxide (TiO2) nanoparticles (NPs) (<100 nm) on viability, membrane integrity, capacitation status and DNA integrity of buffalo spermatozoa. Characterization of NPs was done by the transmission electron microscopy (TEM) and dynamic light scattering (DLS). Sperm chromatin dispersion (SCD) test and acridine orange test (AOT) were employed to detect DNA fragmentation in sperm treated with NPs. There was significant (p < 0.05) decrease in cell viability and membrane integrity (assessed by enzyme leakage) at 6 h of incubation with NPs. However, significant (p < 0.05) increase in sperm capacitation was observed for TiO2 NP albeit at lower concentrations. In DNA fragmentation assay, there was dose-dependent increase in the DNA fragmentation (r = 0.96). Ultrathin cross-sections revealed TiO2 NPs inside head and plasma membrane of the buffalo spermatozoa as assessed by TEM. These studies suggest that TiO2 NPs may have cytotoxic effect on buffalo spermatozoa by affecting sperm functionality and causing high amount of DNA fragmentations.

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