Hydroxymethylation of DNA

DNA methylation, an epigenetic mechanism is claimed to play essential roles in development, aging and disease over the past few decades. Cytosines (C) were known to exist in two functional states: unmethylated or methylated (5mC) in the mammalian genome for a very long time. However, the mechanisms controlling 5mC dynamics remain undefined. Recent studies of genomic DNA on human and mouse brain, neurons and from mouse embryonic stem cells have shown that 2-oxoglutarate and Fe(II)-dependent oxygenases of the ten-eleven translocation (Tet) proteins can catalyze the oxidation of 5mC at cpG dinucleotides to form 5-hydroxymethylcytosine (5-hmC). The exhilarating discovery of these novel 5-hmC has begun to focus on the dynamic nature of 5mC. The prevailing evidence has shown that Tet family proteins and 5-hmC are involved in the normal development as well as in many diseases. This review presents an overview of the role of Tet family proteins and 5-hmC. It also discusses their role as an epigenetic marker and the techniques used for their analysis

Ammonia toxicity: from head to toe?

Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known that the toxic ramifications of ammonia primarily touch the brain and cause neurological impairment. However, the deleterious effects of ammonia are not specific to the brain, as the direct effect of increased ammonia (change in pH, membrane potential, metabolism) can occur in any type of cell. Therefore, in the setting of chronic liver disease where multi-organ dysfunction is common, the role of ammonia, only as neurotoxin, is challenged. This review provides insights and evidence that increased ammonia can disturb many organ and cell types and hence lead to dysfunction

Présence et devenir des hormones stéroïdiennes dans les stations de traitement des eaux usées.

Différents produits chimiques naturels et d’origine industrielle présentent une activité endocrinienne. Ces composés sont susceptibles d’agir sur le système endocrinien des animaux et des êtres humains (altération ou déficiences des fonctions reproductrices, occurrence de tumeurs malignes, etc.). De nos jours, il reste de nombreuses questions en suspens (ampleur de la contamination, devenir dans l’environnement, etc.) et le caractère persistant de ces substances en fait un problème majeur pour les générations futures. De plus, plusieurs études ont montré que les estrogènes naturels (tels que l’estrone, le 17β‑estradiol et l’estriol) et l’estrogène synthétique (17α‑éthinylestradiol) sont les composés les plus oestrogéniques présents dans les effluents de stations de traitement des eaux usées. En conséquence, ces estrogènes peuvent rejoindre les eaux de surfaces et les contaminer. En effet, des concentrations aussi faibles que 0,1 ng/L peuvent provoquer des effets oestrogéniques chez les organismes aquatiques exposés. Cette revue s’est donc concentrée sur la présence de ces types de composé dans les eaux de surface et usées, et plusieurs procédés de traitement sont discutés par rapport à leur capacité d’enlèvement des estrogènes. Ainsi, le traitement primaire seul ne permet pas l’enlèvement des estrogènes des eaux usées, alors qu’un traitement secondaire à boue activée réduit généralement les quantités d’estrogènes. Les procédés dits avancés montrent un potentiel élevé pour l’enlèvement des estrogènes, bien qu’ils peuvent former des sous-produits oestrogéniques et/ou cancérigènes. Finalement, les systèmes enzymatiques pourraient être des procédés innovateurs pour le traitement des estrogènes, puisqu’ils montrent un potentiel élevé pour l’enlèvement des composés aromatiques dans les eaux usées.Various natural chemicals and certain contaminants from industries present an endocrine activity. These substances are likely to act on animal and human endocrine system (deterioration or reproductive functions deficiencies, malignant tumor occurrences, etc). Nowadays, many questions related to these compounds are not resolved and the persistent character of these compounds makes it a major problem for future generations. Furthermore, diverse studies determined that natural estrogens (e.g., estrone, 17β-estradiol and estriol) and synthetic estrogen (17α-ethinylestradiol) are the most estrogenic compounds in wastewater treatment plant effluents. Thus, these estrogens can reach surface water and contaminate it. Indeed, concentrations as low as 0.1 ng/L can induce estrogenic effects in exposed aquatic organisms. This review concentrated on this type of compounds in surface water and wastewater, and a number of treatment processes are discussed with regard to their potential on endocrine disrupting chemicals removal. In the primary treatment effluent, limited removal of estrogens has been observed, while secondary treatment involving activated sludge generally reduces all estrogens effluents concentrations. The advanced processes display a high potential for removing estrogens, although they may produce estrogenic and/or carcinogenic by-products. Enzymatic processes could be an innovative strategy for estrogens removal since they show a high potential to remove aromatic compounds from wastewater

Apoptosis: molecular mechanisms and pathogenicity

Apoptosis triggered by exogenous and endogenous stimuli such as ultraviolet radiation, oxidative stress, and genotoxic chemicals is a crucial phenomenon within biological systems. DNA damage activates and stabilizes p53 in nucleus and cytoplasm and regulates other proteins that stimulate intrinsic and extrinsic apoptotic pathways. Apoptosis is morphologically distinct from that of necrosis and both the phenomena depend on the types, developmental stages, physiological environment of tissues and the nature of death signal. Malfunctioning of apoptotic pathway may cause human diseases like cancer, neurodegenerative and autoimmune disorders. Recently, potent apoptosis-inducing compounds associated with human health have been recorded that prevent tumor promotion, progression, and the occurrence of cellular inflammatory responses. Certain photosensitizing drugs are being employed in photodynamic therapy to induce apoptosis for the treatment of cancer and non-cancerous cells. This review emphasizes the molecular mechanisms of apoptosis, associated diseases and certain therapeutic agents implicated in the elimination of malignant cells

Embedding in Distance Degree Regular and Distance Degree Injective graphs

The eccentricity e(u) of a vertex u is the maximum distance of u to any other vertex of G.The distance degree sequence (dds) of a vertex u in a graph G = (V, E) is a list of the number of vertices at distance 1, 2,. . . , e(u) in that order, where e(u) denotes the eccentricity of u in G. Thus the sequence (di0 , di1 , di2 , . . . , dij , . . .) is the dds of the vertex vi in G where dij denotes number of vertices at distance j from vi . A graph is distance degree regular (DDR) graph if all vertices have the same dds. A graph is distance degree injective (DDI) graph if no two vertices have the same dds. In this paper, we consider the construction of a DDR graph having any given graph G as its induced subgraph. Also we consider construction of some special class of DDI graphs. Keywords: Distance degree sequence, Distance degree regular (DDR) graphs, Almost DDR graphs, Distance degree injective(DDI) grap

DNA damage

Even under the best of circumstances, DNA is constantly subjected to chemical modifications. Several types of DNA damage such as SSB (single strand break), DSB (double strand break), CPDs (cyclobutane pyrimidine dimers), 6-4PPs (6-4 photoproducts) and their Dewar valence isomers have been identified that result from alkylating agents, hydrolytic deamination, free radicals and reactive oxygen species formed by various photochemical processes including UV radiation. There are a number of strategies such as PCR (polymerase chain reaction), comet, halo, TUNEL (Terminal deoxyribonucleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling) assay, HPLC-Electrospray tandem mass spectrometry, FISH (Fluorescence in situ hybridization), FCM (Flow cytometry), annexin V labeling, immunological assays including immunofluorescent and chemiluminescence thymine dimer detection, immunohistochemical assay, Enzyme-linked immunosorbent assay (ELISA), Radio immunoassay (RIA), Gas chromatography-mass spectrometry and electrochemical methods, that are commonly used to detect DNA damage in various organisms. The main aim of this review is to present a brief account of the above mentioned DNA damage detection strategies for the convenience of interested readers

Pyrite nanocrystals: shape-controlled synthesis and tunable optical properties via reversible self-assembly

Nanocrystals from non-toxic, earth abundant materials have recently received great interest for their potential large-scale application in photovoltaics and photocatalysis. Here, we report for the first time on the shape-controlled and scalable synthesis of phase-pure pyrite (FeS2) nanocrystals employing the simple, inexpensive, thermal reaction of iron–oleylamine complexes with sulfur in oleylamine. Either dendritic nanocrystals (nanodendrites) or nanocubes are obtained by adjusting the iron-oleylamine concentration and thereby controlling the nucleus concentration and kinetics of the nanocrystal growth. Pyrite nanodendrites are reversibly assembled by washing with toluene and redispersed by adding the ligand oleylamine. The assembly–redispersion-process is accompanied by an increased absorption in the red/near-infrared spectral region for the aggregated state. This increased low-energy absorption is due to interactions between the closed-packed nanocrystals. High-concentration nanodendrite dispersions are used to prepare pyrite thin films with strong broadband extinction in the visible and near-infrared. These films are attractive candidates for light harvesting in all inorganic solar cells based on earth abundant, non-toxic materials as well as for photocatalytic applications

Hepatotoxicity of Microcystis aeruginosa Strains Growing as Blooms in Certain Eutrophic Ponds

Critical assessment of five eutrophicated ponds of Varanasi city (India) revealed the presence of heavy blooms of cyanobacteria consisting mainly of Microcystis aeruginosa. Crude aqueous extracts of blooms as well as laboratory grown M. aeruginosa isolated from three ponds, namely Lakshmikund, Durgakund and Adityanagar showed toxicity in mouse bioassay test. Crude aqueous extracts from these samples caused death of test mice within 1h of administration (i.p.) with a LD50 of 60 mg/kg body weight and the treated animals showed clinical signs of hepatotoxicity. However such an effect was not associated with the blooms from Laatbhairov and Surajkund ponds suggesting that not all strains of M. aeruginosa are toxic. Based on spectral properties (?max 230 nm), and comparison with standard microcystin-LR, the toxin is tentatively identified as microcystin-LR. The purified toxin caused death of test mice within 40 min of its administration with a LD50 of 100 µg/ kg body weight and induced gross morphological and functional changes in liver. A 1.55 fold increase in liver weight accompanied by deep red coloration most probably due to hemorrhage and blood pooling suggested the hepatotoxic properties of the toxin. Hepatotoxicity was also evident from the drastic increase (up to 2.5 fold) in activity of serum enzymes such as glutamate pyruvate transaminase/alanine aminotransferase (GPT/ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (APase) following toxin treatment. ^14C-labelling experiments demonstrated maximum accumulation (~15%) of ^14C- toxin after 20 min. of toxin administration. Appreciable level of toxin was also detected in water of four ponds. In conclusion these results clearly demonstrate that microcystin-producing blooms of M. aeruginosa are common in eutrophicated ponds of Varanasi city but not all ponds harbour toxic blooms