Genetic integrity of the human Y chromosome exposed to groundwater arsenic

<p>Abstract</p> <p>Background</p> <p>Arsenic is a known human carcinogen reported to cause chromosomal deletions and genetic anomalies in cultured cells. The vast human population inhabiting the Ganges delta in West Bengal, India and Bangladesh is exposed to critical levels of arsenic present in the groundwater. The genetic and physiological mechanism of arsenic toxicity in the human body is yet to be fully established. In addition, lack of animal models has made work on this line even more challenging.</p> <p>Methods</p> <p>Human male blood samples were collected with their informed consent from 5 districts in West Bengal having groundwater arsenic level more than 50 μg/L. Isolation of genomic DNA and preparation of metaphase chromosomes was done using standard protocols. End point PCR was performed for established sequence tagged sites to ascertain the status of recombination events. Single nucleotide variants of candidate genes and amplicons were carried out using appropriate restriction enzymes. The copy number of DYZ1 array per haploid genome was calculated using real time PCR and its chromosomal localization was done by fluorescence in-situ hybridization (FISH).</p> <p>Results</p> <p>We studied effects of arsenic exposure on the human Y chromosome in males from different areas of West Bengal focusing on known recombination events (P5-P1 proximal; P5-P1 distal; gr/gr; TSPY-TSPY, b1/b3 and b2/b3), single nucleotide variants (SNVs) of a few candidate Y-linked genes (DAZ, TTY4, BPY2, GOLGA2LY) and the amplicons of AZFc region. Also, possible chromosomal reorganization of DYZ1 repeat arrays was analyzed. Barring a few microdeletions, no major changes were detected in blood DNA samples. SNV analysis showed a difference in some alleles. Similarly, DYZ1 arrays signals detected by FISH were found to be affected in some males.</p> <p>Conclusions</p> <p>Our Y chromosome analysis suggests that the same is protected from the effects of arsenic by some unknown mechanisms maintaining its structural and functional integrities. Thus, arsenic effects on the human body seem to be different compared to that on the cultured cells.</p

crayfish procambarus clarkii shows circadian variations in different parameters of the gsh cycle

The present study investigated the rhythmic changes in glutathione status in midgut gland and hemolymph as well as in glutathione reductase (GR) activity in the crayfish Procambarus clarkii. In order to determine the circadian nature of these rhythms different groups of crayfish were submitted to constant-darkness conditions for 24 or 72 It after they had spent 15 days under light-dark 12:12 cycles. The animals of the different batches were killed at 6 h intervals during a 24 h cycle. Reduced glutathione (GSH) and oxidized glutathione (GSSG) in hemolymph and midgut as well as midgut GR activity were determined in midgut gland and hemolymph by fluorometric and spectrophotometric methods. Data analysis by chronogram and single Cosinor revealed circadian rhythmicity for GSH and GSSG concentration in both tissues as well as midgut GR activity. The rhythm parameters revealed oxidative stress induced by light. The possible correlation between the glutathione rhythm and other metabolic and behavioral rhythms of crayfish as well as the importance of the glutathione circadian temporal order in the adaptation of crayfish are discussed

glutathione depletion activates mitogen-activated protein kinase (mapk) pathways that display organ-specific responses and brain protection in mice

Because mitogen-activated protein kinases (MAPK) are downstream effectors of antioxidant responses, changes in GSH levels in an organism might induce organ-specific responses. To test our hypothesis, mice were treated intraperitoneally with L-buthionine-S-R-sulfoximine (BSO) to inhibit GSH synthesis. A time-related GSH depletion in the liver and kidney correlated with p38(MAPK) phosphorylation and induction of thioredoxin ! (Tx-1) transcription. This positive regulation was associated with nuclear translocation of NF-kappa B and ATF-2 and gamma-Jun phosphorylation in the liver, but only c-Jun phosphorylation in the kidney. Increased levels of GSH were observed in the brain together with extracellular regulated kinase 2 (ERK2) activation, Nrf2 nuclear accumulation, and increases in transcription of Nrf2, xCT, T-glutamylcysteine synthetase (gamma GCSr), and Tx-1. Pretreatment with MAPK inhibitors SB203580 and U0126, or addition of the exogenous thiol N-acetylcysteine, abrogated both p38(MAPK) and ERK2 activation as well as downstream effects on gene expression. No effect on gamma GCSr was observed. These results indicate that in mice, GSH depletion is associated with p38(MAPK) phosphorylation in the liver and kidney and with ERK2 activation in the brain, in what could be considered part of the brain's protective response to thiol depletion. (C) 2007 Elsevier Inc. All rights reserved

changes in hemolymph glutathione status after variation in photoperiod and light-irradiance in crayfish procambarus clarkii and procambarus digueti

This work studied the effect of light-stressors, irradiance and photoperiod length on the status of hemolymph glutathione in two species of crayfish, procambarus clarkii and Procambarus digueti, Adult animals of each species were submitted to two experimental approaches: (1) two batches of each species were placed under low or high light irradiant conditions of light-dark (LD) 24 h cycles of two different photoperiod lengths, one normal LD 12: 12 and one extreme LD 20:4 low and high irradiance for 10 weeks. Time-dependent light changes on hemolymph glutathione concentration were determined throughout the entire experimental perio

the effect of photoperiod and light irradiance on the antioxidant circadian system of two species of crayfish from different latitudes: procambarus clarkii and a p-digueti

This work was carried out to study the antioxidant circadian system of two species of crayfish of different latitude origin. We investigated (1) whether both species possess glutathione circadian rhythms and (2) whether both species' rhythms differ in their ability to synchronize to 24 h cycles. Two batches of Procambarus clarkii and P. digueti were kept in (1) light-dark (LD) 12:12 low irradiance (LI) cycles and then exposed to (2) 72 h of complete darkness, (3) LD 12:12 high irradiance (111), (4) LD 20:4 LI and (5) LD 20:4 HI for 2 weeks. The midgut and hemolymph were sampled and reduced and oxidized glutathione as well as glutathione reductase and glutathione peroxidase were assayed. Cosinor and analysis of variance revealed differences between both species. Procambarus clarkii robust antioxidant circadian rhythms are able to entrain to all conditions resetting to lights on or off. However, the P. digueti weak circadian glutathione system did not entrain to the LD cycles, showing a random distribution of phases. In this species, LD 12:12 and 20:4 HI evidenced significant daily rhythms indicating a damped circadian antioxidative system that is enhanced by the effect of light. This suggests that each species' photoperiodic history determines the adaptive abilities of the circadian antioxidative mechanisms