Mercury-induced genotoxicity in marine diatom (Chaetoceros tenuissimus).

In this paper, we present an evaluation of genotoxic responses in marine diatom, Chaetoceros tenuissimus, isolated from Kandla Creek (lat 23.03° N, long 70.22° E), Gujarat, India, in terms of impairment of DNA integrity as a function of their exposure to elevated levels of mercury (Hg) under laboratory conditions. DNA integrity in C. tenuissimus was determined by partial alkaline unwinding assay. To our knowledge, this is the first such genotoxicity study to be conducted on marine diatom cultures towards understanding the relationship between Hg toxicity and DNA damage. Furthermore, we studied the impact of Hg on the growth of C. tenuissimus as a function of their exposure to enhanced levels of Hg in terms of decreasing chlorophyll a (chl a) concentrations. The data show the genotoxic effect of Hg on the growth of C. tenuissimus as well as DNA integrity to a great extent. Based on the results of our investigations, it is suggested that C. tenuissimus can be used as sentinel species for bio-monitoring of pollution due to genotoxic contaminants.

Production and purification of recombinant enteropeptidase expressed in an insect-baculovirus cell system.

Enteropeptidase (EC 3.4.21.9) is the glycoprotein enzyme in the small intestine that triggers the activation of the zymogens in pancreatic juice by converting trypsinogen into trypsin. Because of its physiological significance, there have been many studies on the expression, purification, and characterization of enteropeptidase from different species. The baculovirus expression system has been commonly used in research communities and scientific industries for the production of high levels of recombinant proteins, which require posttranslational modifications for functional activity. In the present study, we isolated bovine enteropeptidase catalytic subunit gene from Bos taurus indicus (GenBank accession no. KC756844), and cloned it in pFast Bac HT "A" baculovirus expression donor vector, under the polyhedrin promoter. Recombinant bovine enteropeptidase was expressed in SF-9 insect cells with high expression levels. Recombinant enteropeptidase was purified using Ni-NTA affinity chromatography. A 6-mg quantity of pure active protein was obtained from 100 mL culture using this approach. Its activity and kinetic parameters were determined by cleavage of its fluorogenic substrate Gly-(Asp) 4-Lys-ß-naphthylamide. The recombinant bovine enteropeptidase showed a K m value of 0.75 ± 0.02 mM with K cat 25 ± 1 s.

Genetics of Alzheimer's disease: an insight into presenilins and apolipoprotein E instigated neurodegeneration.

Alzheimer's disease (AD) has long been characterized primarily by extracellular deposition of Aß protein. It is a genetically intricate neurodegenerative disorder. Presenilins (PSs) (presenilin 1 [ PS1] and presenilin 2 [PS2]) and apolipoprotein E (APOE) ε4 allele have been found to be potentially linked to Aß accumulation and accrual in turn contributing for the AD pathology, despite their significant role in processing of amyloid precursor protein (APP) and lipid metabolism. In this review, the role of PSs and APOE in general physiology and AD pathology due to the mutations occurring in them has been discussed. In addition, a few animal models employed to study these mutations and a few therapeutic avenues studied were summarized.

Tau mediated neurodegeneration: an insight into Alzheimer's disease pathology.

Extracellular accumulations of Aß, hyperphosphorylation of tau and intracellular neurofibrillary tangle formation have been the hallmarks of Alzheimer's Disease (AD). Although tau and its phosphorylation play a pivotal role in the normal physiology yet its hyperphosphorylation has been a pathological manifestation in neurodegenerative disorders like AD. In this review physiology of tau, its phosphorylation, hyperphosphorylation with the intervention of various kinases, aggregation and formation of paired helical filaments has been discussed. A brief account of various animal models employed to study the pathological manifestation of tau in AD and therapeutic strategies streamlined to counter the tau induced pathology has been given. The reasons for the failure to have suitable animal model to study AD pathology and recent success in achieving this has been included. The role of caspase cascade in tau cleavage has been emphasized. The summary of current studies on tau and the need for future studies has been accentuated.

Lipid peroxidation in Alzheimer's disease: emphasis on metal-mediated neurotoxicity.

Despite the crucial role of redox active metals like copper and iron in central biological reactions, their elevated levels are involved in the pathogenesis of Alzheimer's Disease (AD). Similarly reactive oxygen/nitrogen species (ROS/RNS) produced during normal metabolic activities, specifically oxidative phosphorylation of the cell, are scavenged by antioxidant enzymes like superoxide dismutase (SOD), catalase but impaired metabolic pathways tend to generate elevated levels of these ROS/RNS. Iron, copper, and zinc are some of the metals, which intensify this process and contribute for the pathogenesis of AD. This review summarizes the mechanism of ROS/RNS production and their role in lipid peroxidation. The factors, which make brain vulnerable for lipid peroxidation, have been discussed. It also focuses on possible treatment options and future directions.