Degradation Kinetics of Caffeine and Related Methylxanthines by Induced Cells of <Emphasis Type="Italic">Pseudomonas</Emphasis> sp.

In this study, the kinetics of degradation of caffeine and related methylxanthines by induced cells of Pseudomonas sp. was performed. The kinetics data showed that degradation of caffeine, theobromine, and 7-methylxanthine followed Michealis–Menten kinetics. The values of K _m are low for caffeine and 7-methylxanthine and high for theobromine. Degradation of caffeine and theobromine was enhanced in the presence of NADH and NADPH, whereas the degradation of 7-methylxanthine was unaffected. Among the various metal ions tested, Fe²⁺ was found to enhance the rate of degradation for all three substrates, whereas Zn²⁺ and Cu²⁺ inhibited the degradation of caffeine and theobromine but not 7-methylxanthine. The differences in kinetic parameters and cofactor requirement suggest the possibility of the involvement of more than one N-demethylases in the caffeine catabolic pathway in Pseudomonas sp. The induced cells can serve as effective biocatalysts for the development of biodecaffeination techniques.     

TNF-induced activation of the Nox1 NADPH oxidase and its role in the induction of necrotic cell death

Tumor necrosis factor (TNF) is an important cytokine in immunity and inflammation and induces many cellular responses, including apoptosis and necrosis. TNF signaling enables the generation of superoxide in phagocytic and vascular cells through the activation of the NADPH oxidase Nox2/gp91. Here we show that TNF also activates the Nox1 NADPH oxidase in mouse fibroblasts when cells undergo necrosis. TNF treatment induces the formation of a signaling complex containing TRADD, RIP1, Nox1, and the small GTPase Rac1. TNF-treated RIP1-deficient fibroblasts fail to form such a complex, indicating that RIP1 is essential for Nox1 recruitment. Moreover, the prevention of TNF-induced superoxide generation with dominant-negative mutants of TRADD or Rac1, as well as knockdown of Nox1 using siRNA, inhibits necrosis. Thus our study suggests that activation of Nox1 through forming a complex with TNF signaling components plays a key role in TNF-induced necrotic cell death.     

Computational insights into diverse aspects of glutathione S-transferase gene family in Papaver somniferum

Journal of Plant Research - Plant glutathione S-transferases are an ancient protein superfamily having antioxidant activity. These proteins are primarily involved in diverse plant functions such as...     

Effect of different light regimes on fitness of two species of Drosophila montium subgroup

Most organisms possess “biological chronometers” in the form of circadian clocks. Organism possessing circadian clock gains fitness advantage in two ways, by synchronizing its behavior through physiological process and secondly by coordinating its internal metabolic process. Environmental manipulations of circadian clocks have been shown to affect many life-history-related traits. Life-history traits are important components of fitness. To enhance individual fitness, organism has to synchronize the physiology with the surrounding environment. The present investigations were made to understand whether rhythm changes affect fitness of two co-existing species of montium a subgroup of Drosophila. The stocks were maintained at 20 ± 1 °C with 75% RH. Fitness such as fecundity, male lifetime fertility, female lifetime fertility, and longevity was assessed in LD (light/dark), LL (continuous light), and DD (continuous dark) for 15 and 30th generations. Fecundity was assessed in 25 pairs of flies for 20 days, and fertility and longevity was assessed in 10 pairs of flies until lifetime. The result revealed differential effect of light regimes on the two different species of Drosophila. Although the two species are related, effect of the three light regimes, LD, LL, and DD on them was different. It is evident that these two species although genetically related exhibit different responses to different light regimes.     

Activation of Autophagic Flux against Xenoestrogen Bisphenol-A-induced Hippocampal Neurodegeneration via AMP kinase (AMPK)/Mammalian Target of Rapamycin (mTOR) Pathways

The human health hazards related to persisting use of bisphenol-A (BPA) are well documented. BPA-induced neurotoxicity occurs with the generation of oxidative stress, neurodegeneration, and cognitive dysfunctions. However, the cellular and molecular mechanism(s) of the effects of BPA on autophagy and association with oxidative stress and apoptosis are still elusive. We observed that BPA exposure during the early postnatal period enhanced the expression and the levels of autophagy genes/proteins. BPA treatment in the presence of bafilomycin A₁ increased the levels of LC3-II and SQSTM1 and also potentiated GFP-LC3 puncta index in GFP-LC3-transfected hippocampal neural stem cell-derived neurons. BPA-induced generation of reactive oxygen species and apoptosis were mitigated by a pharmacological activator of autophagy (rapamycin). Pharmacological (wortmannin and bafilomycin A₁) and genetic (beclin siRNA) inhibition of autophagy aggravated BPA neurotoxicity. Activation of autophagy against BPA resulted in intracellular energy sensor AMP kinase (AMPK) activation, increased phosphorylation of raptor and acetyl-CoA carboxylase, and decreased phosphorylation of ULK1 (Ser-757), and silencing of AMPK exacerbated BPA neurotoxicity. Conversely, BPA exposure down-regulated the mammalian target of rapamycin (mTOR) pathway by phosphorylation of raptor as a transient cell''s compensatory mechanism to preserve cellular energy pool. Moreover, silencing of mTOR enhanced autophagy, which further alleviated BPA-induced reactive oxygen species generation and apoptosis. BPA-mediated neurotoxicity also resulted in mitochondrial loss, bioenergetic deficits, and increased PARKIN mitochondrial translocation, suggesting enhanced mitophagy. These results suggest implication of autophagy against BPA-mediated neurodegeneration through involvement of AMPK and mTOR pathways. Hence, autophagy, which arbitrates cell survival and demise during stress conditions, requires further assessment to be established as a biomarker of xenoestrogen exposure.