Cancer is one of the most unwanted menaces in the human body. Cancers of lower abdomen are not only life threatening but also painful and survival rate is low. Cervical cancer is second most common worldwide and fifth deadliest in women. It affects about 16 per 100,000 women per year and kills about 9 per 100,000 in a year. In developing countries occurrence rate is 80%. It is possible that there may be no symptom until an advance stage of the cancer is progressed. The single cell gel electrophoresis assay also called comet assay, which is versatile, reliable, powerful, uncomplicated and sensitive technique for detection of DNA damage at the level of individual eukaryotic cell. Understanding the extent of DNA damage in neoplastic cells discarded in the urine of cancer patients through comet assay. Usually normal urine sample have very rare cells. In case of cancer patient the number of cells increases drastically. The type of cells passed in the urine of cancer patient contains mainly ...

The Comet Assay, also called single cell gel electrophoresis (SCGE), is a sensitive and rapid technique for quantifying and analyzing DNA damage in individual cells.

Recently, investigators at Universität Ulm have been investigating the low molecular weight DNA diffusion assay (LMW assay) to measure cytotoxicity in comet assays.. The comet assay is a well-established in vitro and in vivo genotoxicity test. However, there has always been concern that the comet assay (as with all DNA strand break assays) may possibly detect exposure-related cytotoxicity rather than genotoxic effects. This is because DNA degradation is frequently involved in processes leading to cell death. Concurrent measures for cytotoxicity are required for standard genotoxicity testing to assess genotoxicity and to address possible effects of cytotoxicity in comet assay data interpretation.. Typically, histopathology has been accepted as a suitable cytotoxicity detection method when using the in vivo comet assay. By looking at the histology, levels of necrosis and apoptosis can be determined. However, there are other assays available for assessing cytotoxicity.. Here, the LMW assay has ...

Taking into account that there are controversial antioxidative effects of inhalational anesthetics isoflurane and sevoflurane and absence of comparison of genotoxicity of both anesthetics in animal model, the aim of this study was to compare DNA damage and antioxidant status in Wistar rats exposed to a single time to isoflurane or sevoflurane. The alkaline single-cell gel electrophoresis assay (comet assay) was performed in order to evaluate DNA damage in whole blood cells of control animals (unexposed; n = 6) and those exposed to 2% isoflurane (n = 6) or 4% sevoflurane (n = 6) for 120 min. Plasma antioxidant status was determined by 3( 4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. There was no statistically significant difference between isoflurane and sevoflurane groups regarding hemodynamic and temperature variables (P > 0.05). Sevoflurane significantly increased DNA damage compared to unexposed animals (P = 0.02). In addition, Wistar rats anesthetized with ...

Self-assembly systems (SAS) mainly consist of micelles, and liposomes are the classes of Nano Drug Delivery Systems with superior properties compared to traditional therapeutics in targeting cancer tumors. All commercially available nano-formulations of chemotherapeutics currently consist of SAS. According to our knowledge, a specific toxicity comparison based on material differences has not yet been performed. The purpose of this study was to evaluate and compare the toxicity of two SAS consisting of Sterically Stabilized Micelles (SSM) made of a lipid-based amphiphilic distearoyl-sn-glycero-phosphatidylethanolamine-polyethylene glycol (PEG)-2000 and a polymeric micelle (PM) consisting of Y-shape amphiphilic block copolymer, synthesized using poly ε-caprolactone and PEG. The mechanism of cytotoxicity and genotoxicity of micelles on L-929 healthy mouse fibroblast cells was assessed using Sulforhodamine-B, WST-1, Acridine Orange/Ethidium Bromide and alkaline single-cell gel electrophoresis assays.

Article Effects of proton beams from the folded tandem ion accelerator on DNA damage in mouse leukocytes using the comet assay. Single cell gel electrophoresis or the comet assay is a sensitive technique to quantify different types of DNA damage, e.g...

The target of the present study is to estimate the in vitro genotoxic potential of the volatile-anaesthetic halothane (Narcotan7) as well as the protective effect of vitamin A, as an antioxidant. To achieve this task, the alkaline single cell gel electrophoresis (comet assay) was applied as the extent of DNA fragmentation in rabbit lymphocytes that were exposed in vitro to halothane at concentrations of 0.1 or 1.0 mM for 10 and 30 min, respectively. The obtained results elucidated that anaesthetic halothane induced a significant increase in DNA damage that shown by comet DNA concentration and its tail length. The recorded elevation of DNA damage was clearly correlated with halothane concentration as well as the period of exposure. To mend the deleterious effect of halothane on DNA, 25 rabbits were orally received vitamin A (8000 IU kg-1 body weight) for 15 days prior to in vitro halothane exposure. Vitamin A administration induced a significant repairing effect in lymphocytes-damaged DNA due to ...

Human dermal fibroblasts (HDFs) are a potential source of somatic cells for genetic manipulation and tissue engineering. Confirmation of cytogenetic stability of these cells is an essential step for cell nuclear transfer and generation of a suitable and functional induced pluripotent stem cells line. HDF cells were isolated and cultured from human foreskin samples. Cytogenetic stability of these cells was evaluated in early (3-4) and late (10-15) passages using karyotype test and alkaline comet assay techniques. HDF cells in early and late passages showed normal karyotype but by comet assay abnormality and DNA damages in late passages of HDFs were observed. Also, the parameters of alkaline comet assay in early passages of HDFs compared with late passages and positive control groups more significantly were different (p , 0.05). These findings indicate that single-strand breaks or DNA damage after many passages may have occurred in HDF cells. Our results demonstrate that only early passages of HDF ...

Nitric oxide (NO) as well as its donors has been shown to generate mutation and DNA damage in in vitro assays. The objective of this study was to identify that DNA single-strand breaks (SSBs) could be elicited by NO, not only in vitro but also in vivo. The alkaline single-cell gel electrophoresis (SCGE) was performed to examine the DNA damage in g12 cells and the cells isolated from the organs of mice exposed to sodium nitroprusside (SNP). A modified method, in which neither collagenase nor trypsin was necessary, was used to prepare the single-cell suspension isolated from organs of mice. Results showed that the exposure of g12 cells to 0.13-0.5 mu mol/ml SNP with S9 for 1 h induced a concentration-dependent increase in DNA SSBs in g12 cells. The significant increase in DNA migration and comet frequency has appeared in the cells isolated from the spleen, thymus, and peritoneal macrophages of mice after injecting i.p. SNP in the dosage range of 0.67-6.0 mg/kg b.wt for 1 h. However, no obvious ...

The economy of the state of Tabasco is based on oil extraction. However, this imposes major effects to the environment and communities. Examples are the Polycyclic Aromatic Hydrocarbons (PAHs) that may be found in the soil, water and sediment of the region. Their volatility makes them available to living beings and results in genotoxic activity. The purpose of this study was to quantify the levels of PAHs in the air at several points in the state, and to analyze their relationship with possible damage to DNA on local inhabitants. Single Cell Gel Electrophoresis Assay (Comet Assay) was applied to peripheral blood lymphocytes of five groups of children between six and 15 years of age. PAH samples were analyzed following US/EPA TO-13-A method. Results indicated the presence in the air of most of the 16 PAHs considered as high priority by EPA, some of which have been reported with carcinogenic activity. Differences (p

This protocol details the experimental procedure for performing the comet assay, a very sensitive DNA break assay based on single cell gel electrophoresis.The analysis of DNA strand breaks, both single- and double-strand breaks (SSBs and DSBs, respectively), was performed in immune resp...

Morphological transformation of C3H/M2 mouse fibroblasts by, and genotoxicity of, extracts of human milk. Breast cancer may be initiated by environmental/dietary agents and human milk may act as an ex vivo indicator of in vivo exposure of mammary epithelial cells to genotoxins. Extracts of human milk from UK-resident women (n = 7) were tested for their abilities to morphologically transform C3H/M2 mouse fibroblasts. Genotoxicities were assessed in the Salmonella typhimurium reverse-mutation assay in the presence of S9 using strains TA1538 and YG1019, and in metabolically-competent human MCL-5 cells with the micronucleus and with the alkaline single cell gel electrophoresis (comet) assays. Two of the seven extracts were inactive in the transformation assay both in the presence or absence of S9, two appeared to be equally transforming either in the presence or absence of S9, and two other extracts induced increased transformation frequencies in the presence of S9. A seventh extract, tested only in ...

Pro-carcinogens, such as benzoapyrene (BaP), that are exogenous ligands of the aromatic hydrocarbon receptor may influence the susceptibility of target-cell populations through the up-regulation of cytochrome P450 (CYP) mixed function oxidases. We examined whether the growth kinetics of MCF-7 cells might determine the level of up-regulation of CYP1A1, CYP1A2 or CYP1B1 by BaP, and whether this could then influence subsequent levels of DNA damage. Cell cultures manipulated to be G0/G1-phase concentrated, S-phase concentrated or G2/M-phase concentrated were treated with BaP and the expression levels of CYP1A1, CYP1A2, CYP1B1, cyclin-dependent kinase inhibitor 1A CDKN1A (P21WAF1/CIP1), B-cell leukaemia/lymphoma-2 (BCL-2), and Bcl-2-associated X levels were determined. Levels of DNA damage were measured as DNA single-strand breaks (SSBs) by the alkaline single-cell gel electrophoresis (comet) assay or as DNA adducts by 32P-postlabelling analysis. BaP-induced up-regulation of CYP1A1 was ...

Ecology affects human organism by causing breaks in DNA and, therefore, induce mutations and malignant cell formation. Comet assay is a quantitative method that allows to measure DNA damage in eukaryotic cells (Liao, McNutt, & Zhu, 2009). This method is widely used in areas, such as human biomonitoring, genotoxicology, and ecology. Comet assay is also called a single-cell gel electrophoresis. Thus, the products of electrophoresis are analyzed under the fluorescent light, which makes it similar to comets. DNA strand breaks are detected by comparing the intensity of the comet tail relative to the head (Collins, 2004). Probiotics containing Lactobacillus rhamnosus were used, as Lactobacilli probiotics were found to be safe and effective against urogenital diseases, food hypersensitivity, and dental caries (Lebeer, Vanderleyden, & De Keersmaeckler, 2008). The aim of the research was to study DNA protector mechanism for three probiotic products, containing L. rhamnosus ...

Within the last decade, the comet assay has been used with increasing popularity to investigate the level of DNA damage in terms of strand breaks and alkaline labile sites in biomonitoring studies. The assay is easily performed on WBCs and has been included in a wide range of biomonitoring studies of occupational exposures encompassing styrene, vinyl chloride, 1,3-butadiene, pesticides, hair dyes, antineoplastic agents, organic solvents, sewage and waste materials, wood dust, and ionizing radiation. Eleven of the occupational studies were positive, whereas seven were negative. Notably, the negative studies appeared to have less power than the positive studies. Also, there were poor dose-response relationships in many of the biomonitoring studies. Many factors have been reported to produce effects by the comet assay, e.g., age, air pollution exposure, diet, exercise, gender, infection, residential radon exposure, smoking, and season. Until now, the use of the comet assay has been hampered by the ...

Comet Assay IV combines accurate, repeatable results with powerful data processing and comprehensive presentation. Once you have obtained your results, you can easily process them using the Spreadsheet Generator, which is included free with every Comet Assay IV system.. The Spreadsheet Generator is an application built in Excel for drawing graphs, tabulating data and calculating statistics from your Comet Assay IV results. Because it is built in Excel, it can easily be customised using any of Excels standard functions and features.. ...

Oxidatively damaged DNA is thought to be important in both the initiation and development of bladder carcinoma. Phytochemical compounds are thought to promote optimal health, partly via their antioxidant effects in protecting cellular components against damaging free radicals. The objective of this study is to assess the effect of a standardised bilberry extract, mirtoselect, on the level of endogenous and induced oxidatively damaged DNA in bladder cancer cells, as assessed by the Comet assay. The Comet assay, also known as single-cell gel electrophoresis, represents a simple method for measuring DNA strand break damage in eukaryotic cells. The sensitivity and specificity of the assay is greatly enhanced by the addition of bacterial repair endonucleases that recognise specific types of damage in the DNA and converts these lesions into additional DNA breaks. - Studies of mirtoselect against three bladder cancer cell lines (RT112, RT4 and HT1376) have shown significant antiproliferative activities ...

We present a procedure for the comet assay, a gel electrophoresisbased method that can be used to measure DNA damage in individual eukaryotic cells. It is versatile, relatively simple to perform and sensitive. Although most investigations make use of its ability to measure DNA single-strand breaks, modifications to the method allow detection of DNA double-strand breaks, cross-links, base damage and apoptotic nuclei. The limit of sensitivity is approximately 50 strand breaks per diploid mammalian cell. DNA damage and its repair in single-cell suspensions prepared from yeast, protozoa, plants, invertebrates and mammals can also be studied using this assay. Originally developed to measure variation in DNA damage and repair capacity within a population of mammalian cells, applications of the comet assay now range from human and sentinel animal biomonitoring (e.g., DNA damage in earthworms crawling through toxic waste sites) to measurement of DNA damage in specific genomic sequences. This protocol ...

TY - JOUR. T1 - DNA damage and breast cancer risk. AU - Smith, Tasha R.. AU - Miller, Mark S.. AU - Lohman, Kurt K.. AU - Case, L. Douglas. AU - Hu, Jennifer H.. PY - 2003/5/1. Y1 - 2003/5/1. N2 - To evaluate whether deficient DNA repair contributes to elevated DNA damage and breast carcinogenesis, we used the comet assay (single-cell alkaline gel electrophoresis) to measure the levels of DNA damage in peripheral lymphocytes from 70 breast cancer cases and 70 controls. DNA damage, measured as the comet tail moment, was not influenced by age, family history (FH), age at menarche, age at first birth or parity. The results showed that cancer cases had significantly higher DNA damage compared with controls; the comet tail moments (mean ± SD) for cases and controls were: 10.78 ± 3.63 and 6.86 ± 2.76 (P , 0.001) for DNA damage at baseline (DB), 21.24 ± 4.88 and 14.97 ± 4.18 (P , 0.001) for DNA damage after exposure to 6 Gy of ionizing radiation (DIR), and 14.76 ± 5.35 and 9.75 ± 3.35 (P , ...

The in vivo genotoxic activity of two inorganic lead compounds was studied in Drosophila melanogaster by measurement of two different genetic endpoints. We used the wing-spot test and the comet assay. The comet assay was conducted with larval haemocytes. The results from the wing-spot test showed that neither lead chloride, PbCl2, nor lead nitrate, Pb(NO3)2, were able to induce significant increases in the frequency of mutant spots. In addition, the combined treatments with gamma-radiation and PbCl2 or Pb(NO3)2 did not show significant variations in the frequency of the three categories of mutant spots recorded, compared with the frequency induced by gamma-radiation alone. This seems to indicate that the lead compounds tested do not interact with the repair of the genetic damage induced by ionizing radiation. When the lead compounds were evaluated in the in vivo comet assay with haemocytes, Pb(NO3)2 was effective in inducing significant increases of DNA damage with a direct dose-response ...

The Comet Assay for detection of DNA repair and DNA damage by tail intensity. In Comet Assays the damage is detected with the single-stranded or double-stranded DNA breaks. DNA damage can be induced by chemicals or UV light radiation. A single cell is paced in low melting agarose on a microscope slide. The cell membrane will be lysed with detergent and salt concentration. Nucleotides will be released from the nucleus and electrophoresis will migrate the damaged DNA to the + anode electric field. The more the DNA is damaged the more there will appear a migration tail. Endonucleases damage increases the DNA migration, whereas DNA-DNA and DNA-protein cross-links result in retarded DNA migration, Tice, 2000. The comet assay is used in DNA repair studies, in animal and clinical studies for base excision repair (BER), nucleotide excision repair (NER) like the Vitotox L. Gevaert, 2009 measures the cytotoxicity in Salmonella lux promotor cloned cells. They show that the Comet Assay or single cell gel ...

Those who defend the planet ignore comets, and its due to wrong perception that comets cant be stopped. Its difficult to track the ice bodies as said by Nuth, but we can prevent it if we get prepared.. Get the Free Tracker App to find 2018 NES Classic in Stock. Comets are dangerous. The research reveals that its easy to deal with asteroids, because they are common. Its easy to detect NEAs, Near Earth Asteroids than comets, because NEAs are just like our planet. But, comets exist deep in the external solar system, so they are difficult to detect. According to scientists, the Halley comet revolves around sun once in every 75 years.. According to Nuth, comets suddenly appear from nowhere. He said that comet named Siding Spring appeared in 2013 and 2014 striking Mars, and both were dangerous. A space aircraft can destroy comet, but it takes 5 years to prepare a spacecraft, said by Nuth in AGU conference. Comet is larger than NEAs, so they strike the earth at high velocity.. On the contrary, NEA ...

Seven flavonoids were isolated from Eremosparton songoricum (Litv) Vass and their antioxidation actions were examined. To investigate protective ability against DNA damage induced by H2O2, human peripheral blood mononuclear cells (PBMCs) were incubated with 5-hydroxy-7,4′-dimethoxyflavone,5,7-dihydroxy-3′,4′-dimethoxyflavone, acacetin, chrysoeriol, pedalitin, flavogadorinin and 5,7,4′-trihydroxy-3′-methoxyflavone-4′-O-D-glucoside separately and then treated by H2O2. The percentage of damaged cells were determined by single-cell gel electrophoresis. To examine their inhibition of lipid peroxidation, the compounds were incubated with rat microsomes and the reaction was initiated by Fe2+/Vc. The lipid peroxidation product thiobarbituric acid reactive substances (TBARS) was determined. The result showed most of flavonoids had concentration-dependent antioxdative activities. The relationship of antioxidation and the structure is discussed.

PubMed journal article: Validation of Drosophila melanogaster as an in vivo model for genotoxicity assessment using modified alkaline Comet assay. Download Prime PubMed App to iPhone, iPad, or Android

BioTek Note applicative, 07-Jul-16, Automated Comet Assay Imaging and Dual-Mask Analysis to Determine DNA Damage on an Individual Comet Basis

Just download these files into the extras folder of Celestia and you are ready to go (despite the comet only being magnitude 10, Celestia exagerates the comets tail and brightness, it does this for all comets around perihelion, but it makes them easy to find). You can get a whole passel of comet orbitals from the Celestia motherlode comet section, but be aware that the 164P-Christensen obits here are the old, pre-recovery orbits (also, if you load in the full catalog of comets, they sky will be taken up by comet orbits, best to use that as a resource to extract comets as you need them ...

The concept underlying the SCGE assay is that undamaged DNA retains a highly organized association with matrix proteins in the nucleus. When damaged, this organization is disrupted. The individual strands of DNA lose their compact structure and relax, expanding out of the cavity into the agarose. When the electric field is applied the DNA, which has an overall negative charge, is drawn towards the positively charged anode. Undamaged DNA strands are too large and do not leave the cavity, whereas the smaller the fragments, the farther they are free to move in a given period of time. Therefore, the amount of DNA that leaves the cavity is a measure of the amount of DNA damage in the cell. The image analysis measures the overall intensity of the fluorescence for the whole nucleoid and the fluorescence of the migrated DNA and compares the two signals. The stronger the signal from the migrated DNA the more damage there is present. The overall structure resembles a comet (hence comet assay) with a ...

The genotoxic effects of 2.45 GHz microwave (MW) radiation on the testis and ovary of Sprague Dawley rats was investigated. The animals were exposed to varying levels of specific absorption rate (SAR) of 0 (control), 0.48, 0.95, 1.43, 1.91, 2.39, 2.90, 3.40, 3.80 and 4.30 Wkg-1 , for 10 min. The induction of DNA damages was assessed using DNA direct amplification of length polymorphisms (DALP) and validated with single cell gel electrophoresis (SCGE) comet assay for same cells at SAR 2.39 Wkg-1 . Potential damage at the organ level was assessed by histopathological study. The results show significant differences in the Olive moment and % DNA in the blood of the exposed animals when compared with the control (p , 0.05). Hyperchromasia was observed in the ovary of the animals exposed to MW radiation. Also, there was reduction in the number of germ cells and cell disorganization in the testis of exposed group with increasing SARs. These results suggest that MW radiation has the potential to affect ...

The genotoxic effects of 2.45 GHz microwave (MW) radiation on the testis and ovary of Sprague Dawley rats was investigated. The animals were exposed to varying levels of specific absorption rate (SAR) of 0 (control), 0.48, 0.95, 1.43, 1.91, 2.39, 2.90, 3.40, 3.80 and 4.30 Wkg-1 , for 10 min. The induction of DNA damages was assessed using DNA direct amplification of length polymorphisms (DALP) and validated with single cell gel electrophoresis (SCGE) comet assay for same cells at SAR 2.39 Wkg-1 . Potential damage at the organ level was assessed by histopathological study. The results show significant differences in the Olive moment and % DNA in the blood of the exposed animals when compared with the control (p , 0.05). Hyperchromasia was observed in the ovary of the animals exposed to MW radiation. Also, there was reduction in the number of germ cells and cell disorganization in the testis of exposed group with increasing SARs. These results suggest that MW radiation has the potential to affect ...

diversity among more than two dozen comets observed to date.. Tony Farnham (University of Maryland, College Park, Maryland) is an astronomer who studies the dynamics of cometary nuclei and the interrelationship between a comets nucleus and its coma. He was a member of the Science teams for the Deep Impact mission to comet Tempel 1, the extended mission (DIXI) to comet Hartley 2, and the Stardust-Next mission that returned to comet Tempel 1. He also led one of the teams that performed the analysis of the dust hazards posed by comet Siding Spring during its close approach to Mars.. Kelly Fast (NASA Headquarters) [Bio coming soon...] Yan Fernandez (University of Central Florida, Orlando, FL) is an astronomer who has been studying comets and asteroids since the mid-1990s. He has studied comets, asteroids, Trojans, Centaurs, and small moons at IR, visible, and radio wavelengths for over ten years with the goal of determining their physical and compositional properties. He is the PI of the Spitzer ...

The genotoxicity of jet propulsion fuel 8 (JP-8) was assessed in the leukocytes of archived blood specimens from U.S. Air Force personnel using the comet assay. No differences in mean comet assay measurements were found between low, moderate, and high exposure groups before or after a 4 hour work shift. Before the work shift, mean tail DNA and mean tail (Olive) moment increased as the concentratio

A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earths diameter, while the tail may stretch one astronomical unit. If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.. Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets ...

879 Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants implicated in the causation of human lung cancer. One pathway of metabolic activation that yields reactive oxygen species (ROS) involves the oxidation of PAH trans-dihydrodiols by aldo-keto reductases (AKRs) to yield reactive and redox-active o-quinones, which can cause oxidative DNA damage (e.g. 8-oxo-dGuo). Evidence for this pathway in lung cells has been hampered by the difficulty in detecting 8-oxo-dGuo levels reliably in intact cells. We used the single cell gel electrophoresis (Comet) assay to detect DNA strand breaks in human lung adenocarcinoma (A549) cells (which express AKR1A1 and AKR1C isoforms) following treatment with BP-7,8-diol (AKR substrate), and BP-7,8-dione (AKR-product) and (+)-anti-BPDE. In the presence of DNA synthesis inhibitors (cytosine arabinoside and hydroxyurea) all three PAH metabolites produced significant DNA strand breaks in a concentration-dependent manner. Inclusion of ROS scavengers ...

The comet assay is a sensitive, well established technique for quantifying DNA damage in eukaryotic cells. Compatible with the detection of a wide range of DNA damaging agents, its principle consists in migration of fragmented DNA in an electrophoresis gel (damaged DNA forming the tail of the comet), while intact DNA moves at a slower rate (head of the comet). The percentage of fragmented DNA in the comet tail is a direct measure of DNA damage.. ...

Comet NEOWISE graces skies of far northern Californias Pacific and Redwood coasts, Humboldt County, California. What is a comet, and why do we see it? Comets are made of ice, rock and dust, like a dirty snowball. The ice may comprise any of a number of gases, frozen into a solid state in the icy blackness of space. As comets approach the sun, the suns energy acts on the comets surface, causing molecules of the ice to sublimate, or become gas again without going through a liquid state. As this happens, some larger particles of dust and debris making up the comet nucleus, or solid center, are blown outward into the surrounding space. This combination of gasses and larger particles surrounding the nucleus makes the hazy head, and forms the tail(s).

These high cliffs occur on the surface of a comet. They were discovered to be part of the dark nucleus of Comet Churyumov-Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA which began orbiting the comet in early August. The ragged cliffs, as featured here, were imaged by Rosetta about two weeks ago. Although towering about one kilometer high, the low surface gravity of Comet CG would likely make a jump from the cliffs, by a human, survivable. At the foot of the cliffs is relatively smooth terrain dotted with boulders as large as 20 meters across. Data from Rosetta indicates that the ice in Comet CG has a significantly different deuterium fraction -- and hence likely a different origin -- than the water in Earths oceans. The Rosetta spacecraft is scheduled to continue to accompany the comet as it makes its closest approach to the Sun in 2015 August. via NASA http://ift.tt/ ...

Hydrogen, Lead, Ability, Alkaline Comet Assay, Alkylation, Alkylators, Blood, Cancer, Cell, Cells, Chromatography, Comet Assay, Concentration, Concentrations, DNA, DNA Damage, Epithelial Cells, Ethylene Oxide, Gas Chromatography, Human

The software applies state of the image processing methods to automatically locate and score comets to characterize and quantify the degree of DNA damage revealed by the comet assay. It is compatible with 4X images which allows for rapid screening of up to 300 comets in seconds when analyzing CometChip®. Trevigens Comet Analysis Software can rapidly evaluate large numbers of cells, related to each treatment group or screening target in a study, and generate summary statistics based on the corresponding numeric results.. ...

Two approaches were used to induce DNA strand breaks. On the one hand, FANCD1-/- fibroblasts were treated with a PARP inhibitor to inhibit DNA repair. For comparison, wild type cells were treated the same way. On the other hand, wild type fibroblasts were treated with hydrogen peroxide, which causes oxidative damage to DNA, including single- and double-stranded breaks. The latter samples were also analysed by the comet assay for comparison to 2D-SDE. The comet assay is the commonest detection method for DNA strand breaks and one of the objectives of the development of 2D-SDE is to design a method that is less time-consuming and easier to carry out than the comet assay ...

Molecular oxygen is two oxygen atoms joined together, and on Earth it is essential for life, where it is produced by photosynthesis. It has been previously detected around some of the icy moons of Jupiter, but it was not expected to be found around a comet. The Rosetta science team originally reported that the oxygen was most likely from the comets main body, or nucleus. This meant it was primordial - that it was already present when the comet itself formed at the beginning of the Solar System 4.6 billion years ago. One group of outside researchers however suggested there might be a different source for molecular oxygen at comets. They had discovered a new way to produce molecular oxygen in space triggered by energetic ions-electrically charged molecules. They proposed that reactions with energetic ions on the surface of comet 67P could instead be the source of the detected molecular oxygen. Now, members of the Rosetta team have analysed the data on 67Ps oxygen in light of the new theory. In ...

The SWAN data captured another surprise. On Sept. 30, the hydrogen jumped by a factor of two and a half in a single day. It dropped down again some six weeks later.. Standard models of how comets behave helped Combis team correlate the hydrogen signature to just how much of the comets surface should be giving off water, a process known as sublimating, because the water turns directly from ice to a vapor without passing through a liquid phase. The amount of surface area predicted didnt jibe with what EPOXI itself saw - a comet that only gave off water from one half of its shape. But EPOXI also captured images of an extended halo of icy fragments that burst off the comet, most likely flung into space by carbon dioxide emissions on the comets surface. These ice chunks probably added sublimated water to the hydrogen cloud.. The rate of water generation being so much higher in 1997 implies that the ice fragmentation was even more severe then, says solar physicist Joe Gurman, U.S. project ...

We present a sensitive 3 sigma upper limit of 1.1% for the HNC/HCN abundance ratio in comet 73P/SchwassmannWachmann (fragment B), obtained on 2006 May 10-11, using Caltech Submillimeter Observatory (CSO). This limit is a factor of ~7 lower than the values measured previously in moderately active comets at 1 AU from the Sun. Comet 73P/Schwassmann-Wachmann was depleted in most volatile species, except of HCN. The low HNC/HCN ratio thus argues against HNC production from polymers produced from HCN. However, thermal degradation of macromolecules, or polymers, produced from ammonia and carbon compounds, such as acetylene, methane, or ethane appears a plausible explanation for the observed variations of the HNC/HCN ratio in moderately active comets, including the very low ratio in comet 73P/Schwassmann-Wachmann reported here. Similar polymers have been invoked previously to explain anomalous N-14/N-15 ratios measured in cometary CN. ...

Because of their temporal and spatial variations, modern ground-based studies of comets within approximately 4 A.U. of the sun are observationally demanding tasks. Over the years, researchers have attempted resolved spectroscopy of comets covering a wide range of intrinsic luminosity. Recently this group has developed spectral and direct-imaging procedures to detect weak ion tails submerged into the comae of even fairly faint comets. Although the last year was devoid of any really bright comet, re-analysis of older dust and gas production data of the 1986 P/Halley apparition has been almost completed. The main changes are that the nucleus does make a significant contribution to continuum light, and that the gravity effect in the dust escape velocity is somewhat larger than previously assumed. On the direct observational side, spectral studies of the 1987s Comet Bradfield show it to be qualitatively carbon-rich, at least in the outer coma ratio of CO(+) and CO2(+), compared the H2O(+) with respect to

7. The scientific papers and popularized book by S. V. M. Clube and W. M. Napier [Nature, 282 (29 November, 1979), P. 45S; Q. JI. Asir. Soc. (1982),23, pp. 45-66; and The Cosmic Serpent (London and New York, 1982)] deserve comment in light of the present paper. Their statement to the astronomical community that Velikovsky was at least close to correct and that comets (and in particular a body named Venus) did play important roles in early civilizations is long overdue. They also recognize the irrational behavior with which scientists confronted Velikovsky, and the overwhelming data pointing towards worldwide catastrophism caused by comets. I maintain, however, that Clube and Napiers findings support the present paper more precisely than their own theory of terrestrial catastrophism. Both papers agree that comets are of interstellar origin, and that the primordial Oort cloud concept does not explain the observed comet flux in the solar system. They support the ice ball comet model, ...

Ever since its formation, the Earth has been bombarded by comets, and scientists think they now have evidence that these cosmic missiles could have carried the building blocks for life along with them when they impacted.. In 2009, NASAs Stardust mission rendezvoused with the comet Wild-2 and returned to Earth with a sample of an amino acid the probe had picked up from comets outgassing. Tests showed it had too much carbon-13 to have come from Earth, but skepticism remains that simple amino acids could have kick-started the development of life on the planet.. To test that hypothesis, a team of scientists at the University of California, Berkeley, and the University of Hawaii, Manoa, built a pseudo-comet in the lab - a snowball of carbon dioxide, ammonia, and various hydrocarbons such as methane, ethane, and propane - then chilled it in an ultra-high-vacuum chamber down to 10 degrees above absolute zero.. The comet was then zapped with high-energy electrons to simulate the cosmic rays it would ...

Our experience with Red Comet was very easy and smooth. We needed to use Red Comet during the pandemic to fulfill some of my childs requirements to graduate. The school district accepted the classes and she was off. She was able to pace herself and get the work done when she had time. She set a schedule for herself and met many of those timeline dates with the help of Red Comet organization structure. I would highly recommend Red Comet classes as a substantive learning tool for high school students. ...

http://www.godlikeproductions.com/forum1/message3383800/pg1. People are talking about a large comet that is supposedly visible to the naked eye and will be passing on NYE. This is supposed to go down while partyers are out in the streets, waiting for the ball to drop. Some website forums are spelling doom for society and talking about elites taking to underground bunkers in anticipation of the comet slamming into Earth.. This all very closely resembles the plot of the classic 80s camp sci-fi classic Night of the Comet. 80s camp films have a lot of social criticisms embedded in them, which are poignant, and often overlooked. In that film, those who follow the crowd (and stand in the streets watching the comet) are turned into a pile of red dust. Only their sneakers and clothes remain. Just like holiday shoppers -even the survivors in the film would mostly rather go fashion shopping than worry about more practical type things. Meanwhile scientists are living in underground bunkers, aiming to ...

Reduction of comet tail artifacts using image restoration algorithms. Microspheres (15.4 μm diameter) were embedded in O.C.T phantom, imaged, and processed. MIPS of a sub volume are shown. The unprocessed image (a) shows the comet tail artifact extending to a depth of ≈100 μm. RL processing (b) removes comet tail artifacts and restores the shape of the bead both in-plane and along Z. Next-image processing (c) reduces the comet tail artifacts but in-plane spread persists. Wiener deconvolution (d) removes comet tail artifacts but the resultant image suffers from high frequency noise and in-plane restoration is not as effective as in RL. Parameters were: voxel size 4x4x5µm3, (RL, 20 iterations, damping factor of 3), and Wiener, NSR = 10−4. Scale bar corresponds to 50 µm ...

The reaction of ancient peoples to the appearance of bright comets has toppled empires, de-throned kings, and been taken as a sign of great things to come. Probably some of these comets did not get as bright as Comet Hyakutake (hyah-koo-tah-kay) will in the next two weeks. It is likely that every major news organization will soon cover Comet Hyakutake extensively. Comet Hyakutake is shown above already showing a tail of dust. This image, taken directly from a photographic negative, shows stars as black spots and the bright comet coma and tail as dark clouds against the white background of space. During its closest approach to the Earth on March 25th, Comet Hyakutake will appear in the Northern hemisphere as a diffuse ball of light brighter than most stars. Comet Hyakutake will be visible then most of the night even without binoculars, passing above the stars in the handle of the Big Dipper. Comet Hyakutake will be best seen in dark skies far from city lights, where its tail - possibly ...

Smearing and smiling in GelRed™ or GelGreen™ precast gels most often caused by overloading of DNA. If you see band migration shifts or smearing and smiling, try reducing the amount of DNA loaded. The recommended loading amount for ladders and samples of known concentration is 50-200 ng/lane. For samples of unknown concentration, try loading one half or one third of the usual amount of DNA. This usually solves band migration problems.. Tip #2: Try the post-staining protocol. To avoid any interference the dye may have on DNA migration, we recommend using the post-staining protocol. If your application requires loading more than the recommended amount of DNA, use the post-staining protocol. While we recommend post-staining gels for 30 minutes, you may be able see bands in as little as five minutes, depending on how much DNA is present. Post-staining solutions can be reused. See the GelRed™ Product Information Sheet or GelGreen™ Product Information Sheet for detailed protocols.. Other tips ...