171,657 research outputs found
Restriction endonuclease Bam H I induces chromosomal aberrations in Chinese hamster ovary (CHO) cells.
No full textTreatment of Chinese hamster ovary (CHO) cells with the restriction endonuclease Bam H I (recognition site: G/GATCC) leads to high frequencies of chromosomal aberrations. Experiments with bromodeoxyuridine-labelled chromosomes show that the aberrations occur nearly exclusively in first post-treatment metaphases. The results are interpreted to mean that only some of the cells take up the enzyme and that these cells are the ones showing the aberrations. Cells which do not take up the enzyme show up as differentially stained metaphases and have no aberrations. Why some cells take up the restriction enzyme and others not is not known, possibly this is dependent on the physiological condition of the cells
Direct and indirect non-disjunction in the origin of trisomy in cultured human lymphocytes
No full textThe aim of the present work was to investigate the processes involved in the origin of trisomic karyotypes, i.e. co-migration of sister chromatids (mitotic non-disjunction, MND) and recovery of micronuclei (MN) originating from lagging chromosomes/chromatids at anaphase (mitotic indirect non-disjunction, MIND), and to evaluate their relative contribution to aneuploidy in human lymphocytes mitotically activated in vitro. Therefore, phytohaemagglutinin-stimulated human lymphocytes from one donor were treated with 10 and 25 nM colchicine and analysed through two cell cycles by means of both molecular (FISH with centromeric DNA probes specific for chromosomes 7 and 11) and classical cytogenetic techniques. The following events were analysed: (i) chromosome/chromatid Loss (a MN-generating event) in M-1 bipolar ana-telophases; (ii) MN recovery in M2+ prophases; (iii) non-disjunction and loss of chromosomes 7 and 11 by FISH analysis in cytochalasin B-induced binucleate cells; (iv) spontaneous frequency of trisomic cells by chromosome counting and FISH analysis in M-1 c-metaphases; (v) induced frequency of trisomic cells by chromosome counting and FISH analysis in M-2 c-metaphases. Our results indicate that MND plays a major role compared with MIND in the origin of trisomic karyotypes, being similar to 4- to 5-fold higher in colchicine-treated cells. Moreover, remarkable reductions in the observed frequencies of trisomic cells were recorded in comparison with the expected ones, with an observed/ expected frequency ratio of trisomic M-2 c-metaphases ranging between 1/3 and 1/6
Effect of cytochalasin B on the induction of chromosome missegregation by colchicine at low concentrations in human lymphocytes
No full textThe aim of the present work was to investigate the possible interference of cytochalasin B (cyt B) with low concentration treatment with colchicine in the induction of chromosome/chromatid loss and micronuclei in human lymphocytes mitotically activated in vitro. Thus, cells from a single female donor were treated with colchicine (10 or 25 nM, from 24 h after PHA addition to fixation at 66 h) either in the presence or absence of cyt B. Single lagging chromosomes/chromatids were scored in bipolar ana-telophases and greater damage (disrupted and c-anaphases) was scored in cells at anaphase. Micronuclei were scored in the first 4000 nuclei observed in both cyt B-treated (in mononucleate and binucleate cells) and untreated cultures. With the same criterion, FISH analysis was performed on 2000 nuclei where chromosome 7 and 11 centromeric DNA probes were used in pairs. Our results showed that: (i) the frequency of laggards and of micronuclei increased with colchicine concentration but in the presence of cyt B there was a lower frequency of both (with a mean reduction of ~ 49%); (ii) FISH analysis showed a colchicine concentration-dependent increase in nuclei with three spots for chromosome 7; (iii) a colchicine concentration-dependent increase in tetraploid cells was observed. This increase was particularly remarkable (5-fold) in cells grown in the presence of cyt B compared with cyt B-untreated cells. The observed 'cyt B effects' can be explained if it is assumed that in cytokinesis-blocked cells there is a shorter distance between the poles. As a consequence: (i) laggards would be engulfed in the nearest daughter nucleus with a consequent lower induction of micronuclei; (ii) segregating sister chromatids in heavily impaired anaphases would not travel a sufficient distance to give rise to two daughter nuclei, leading to an increased frequency of polyploid nuclei
Influence of Temperature on Mutagenicity in Plants Exposed to Surface Disinfected Drinking Water.
No full textDisinfection of surface drinking water, particularly water chlorination, produces by-products with potential genotoxic and/or carcinogenic activity. A study carried out at a pilot plant for drinking water disinfection of lake water revealed mutagenic activity of three different disinfectants (sodium hypochlorite, chlorine dioxide and peracetic acid) in different seasons using in situ mutagenicity assays, both in animal (micronucleus test) and in plant organisms (anaphase chro- mosomal aberration and micronucleus tests). The effects of the disinfectants appeared to be modulated by the season of exposure. In this study, we tried to understand if (and to what extent) the temperature parameter could actually play an independent role in the registered seasonal variation of mutagenic effects, neglecting the variation of other parameters, e.g. physical conditions and chemical composition of the lake water. Therefore plants (Allium cepa for chromosomal aberration test and Vicia faba for micronucleus test) were exposed to the same disinfected lake-water samples at differ- ent temperatures (10°C, 20°C and 30°C), according the ones registered during the in situ experiment. Long-term expo- sure at the temperatures of 20°C (both Vicia faba and Allium cepa) and 30°C (Vicia faba only) to disinfected waters in- duced clear mutagenic effects. These results show that temperature is an important variable which should be taken into account when in situ exposure of plants is planned for mutagenicity testing. Also, different plant systems clearly show specific temperature ranges suitable for their growth, thereby indicating the need for an accurate selection of the test organism for a specific experimental plan
An integrated approach to the assessment of the environmental quality of the Tiber river in the urban area of Rome: A mutagenesis assay (micronucleus test) and an analysis of macrobenthic community structure
No full textOur aim was to study the environmental pollution of the river Tiber within the urban area of Rome. We studied both the stress of the macrobenthic communities, described by density (calculated as animal biomass) and diversity (calculated with the Shannon index), and the mutagenic effects of waters and sediments, using the micronucleus test in root tips of Vicia faba. Four places (stations) were studied: (1) Castel Giubileo, at the entry of the urban area; (2) Ponte Tor di Quinto, immediately after the confluence of the tributary river Aniene; (3) Ponte Matteotti, at the entry of the historical city center; and (4) Ponte Sublicio, in the middle of the city center. Samples were collected in spring (May, 1989) with an intermediate pollution level, winter (January 1990) with a low one, and late summer (September 1990) with a high one. There is agreement between the environmental damage, measured by diversity of macroben_ thic community, and the mutagenic effect of media (water and sediments), identified by micronuclei: while Castel Giubileo shows an acceptable condition in all the seasons, and Ponte Sublicio a bad one, the intermediate stations show a recovery in January
Green carbon dots developed from biomass for sensing marine biotoxin
No full textINTRODUCTION: Biomass waste has a lot of promise for creating inexpensive carbon-based nanomaterials for electrochemical sensing applications. This study presents the preliminary results of an immunosensors for a seafood biotoxin detection using Screen Printed Electrodes (SPEs) modified with green nanostructures to enhance their electrochemical performances. With this goal, two green CDs compounds, derived from fish and cork powder, were used to modify the graphite SPEs. These electrodes provide an economical and sustainable way to create carbon-based sensors using biomass sources. OBJECTIVE: The purpose of this study is to assess the development of an electrochemical immunosensor for saxitoxin (STX) based on SPE modified with green carbon dots (CDs) made from Cork powder and Fish scales (poster by Gustavino - Cytogenotoxicity studies on green carbon dots developed from biomass for biosensing applications) with label free approach. Saxitoxin is one of the most lethal non-protein toxins (LD50 9 mg Kg-1)1,2 and is known as one of the "Paralytic Shellfish Poisons" (PSP), produced by several marine dinoflagellates and freshwater algae. Contamination of shellfish with saxitoxin has been associated with harmful algal blooms throughout the world. In humans, PSP causes dose-dependent perioral numbness or tingling sensations and progressive muscular paralysis, which may result in death through respiratory arrest3. For these reasons it is very important to develop an innovative nanosystem integrating ultrasensitive saxitoxin (STX) detection with sustainable bionanomaterials. This system enables rapid, ultrasensitive monitoring of marine biotoxins to safeguard seafood safety and marine ecosystems, while valorizing industrial byproducts to reduce waste and align with circular economy goals—bridging environmental stewardship with cutting-edge analytical science and aquatic biotechnology. MATERIALS AND METHODS: Preparation of green carbon dots from Fish Scale & Gill (FSG-CDs) and cork (C-CDs): FSG-CDs & C-CDs prepared by the hydrothermal method – using just water as green solvent – of the FSG powder of the Nile tilapia (Oreochromis niloticus) & cork powder by applying the heating programs in a Teflon-based autoclave at 200°C for 12 h. Preparation of label-free electrochemical immunosensor for STX detection: The green FSG-CDs & C-CDs are used to modify by drop casting the surface
of screen-printed electrodes (SPEs). Electrochemical characterisation using cyclic voltammetry and square wave voltammetry are used in order to optimise the amount of the deposition, the solvent, the better green material and the storage.
RESULTS: In this work, a disposable, simple and low-cost platform for immunosensing applications is reported using SPE modified with green CDs. The serigraphic sensor exhibited a low detection limit, good sensitivity, reproducibility, selectivity and storage stability with both proposed materials, paving the way for its potential exploitation for the detection of STX in a wide range of real matrix samples, such as water or mussel
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
SISTER CHROMATID EXCHANGES INDUCED BY DNA DEMETHYLATING AGENTS PERSIST THROUGH SEVERAL CELL-CYCLES IN MAMMALIAN-CELLS
No full textEukaryotic DNA methylation has been extensively studied in recent years. The ability of many carcinogens to interfere with DNA methylation has not yet been directly related to their tumorigenic activity. Recent data obtained using L-ethionine and 5-azacytidine--both demethylating agents--showed a small but significant increase in the sister chromatid exchange (SCE) rate induced in mammalian cells (human lymphocytes and CHO cells). In this paper we show that the SCE increase induced by both these agents in Chinese hamster ovary (CHO) cells persists for as long as 10 cell cycles. On the other hand mitomycin-C and u.v. light-induced SCEs show a rapid decrease to the control value, as reported for all known SCE inducers. We suggest that DNA demethylation and SCEs are connected through a perturbation of the cell machinery at the level of the replication fork, producing an increase of the error-prone ligation. Since the methylation level is maintained (inherited), the SCE increase produced by these recombinational events will not be corrected through several cell cycles
Mitotic indirect non-disjunction in phytohemagglutinin stimulated human lymphocytes
No full textIn a previous publication we demonstrated that in cells of Vicia faba micronuclei derived from whole lagging chromosomes or chromatids may perform DNA synthesis and mitotic condensation in synchrony with main nuclei and be regained by main nuclei at the next mitosis, giving rise to trisomic cells together with diploids. This process was called 'mitotic indirect non-disjunction' (MIND). In the present work the occurrence of MIND was studied in human lymphocytes cultivated in vitro. Human lymphocytes were treated with low colcemid concentrations until fixation; BrUdR was supplied together with colcemid to distinguish the number of mitoses performed by the cells (M1, M2 and M3 cells). The frequencies of M1 ana-telophases with single lagging chromosomes/chromatids and of M2+ prophases with single micronuclei in synchronous motitic condensation with main nuclei were evaluated. On this basis the expected frequencies of both monosomic and trisomic M2 cells were calculated, according to the hypothesis of MIND. Their observed frequencies were very close to those expected. These results support the hypothesis of the occurrence of MIND in human lymphocytes
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
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