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Formation of DNA adducts in the gill tissue of Mytilus galloprovincialis treated with benzo[a]pyrene.
No full textThe formation of DNA adducts was evident after treatment of spawned or resting Mediterranean mussels (Mytilus galloprovincialis Lmk.) with 0.5-100 mu g/l of benzo[a]pyrene for 2 and 3 days. Reference DNA samples, in vitro radiolabelled with 0.5, 5, 50 mu M H-3-anti (+/-)-B[a]P-diol-epoxide, were initially used to compare two DNA purification procedures. Following a standard four-step extraction starting with phenol, in comparison to a simplified single-step extraction without phenol, we obtained lower yields of bound radioactivity in the reference DNA samples. After simplified DNA purification and nuclease P1 enhanced P-32-postlabelling assay we detected a reproducible dose-dependent increase of a specific spot in gills of mussels treated with B[a]P, although this spot was present in low amounts. Short (2 days) and prolonged (27 days) pretreatment of mussels with a polychlorinated biphenyl mixture, Aroclor 1254, did not increase the levels of B[a]P-related adducts. On the whole, these results indicate the formation of detectable amounts of DNA reactive intermediates in gills of mussels treated with B[a]P. Although the pathway of formation and the molecular identity of the specific adducts remain unclear, their presence suggests that polycyclic aromatic hydrocarbons may cause genetic damage in marine mussels
DNA adducts in Mytilus galloprovincialis and Zosterisessor ophiocephalus collected from PAC-polluted and reference sites of the Venice lagoon.
No full textMediterranean mussels (Mytilus galloprovincialis) and bottom-dwelling grass gobies (Zosterisessor ophiocephalus) were collected from the Venice lagoon both in front of the open sea and from the industrial area of Porto Marghera. DNA adducts were measured by means of the nuclease P1-enhanced 32P-DNA postlabelling assay. Autoradiograms of gill DNA from animals of the industrial area showed a tract of unresolved adducts along the diagonal radioactive zone. Such adducts were detected at low but significant levels in different sampling periods only in mussels and fish collected at Porto Marghera. The presence of bulky aromatic DNA adducts in native mussels is consistent with previous results on the appearance of a weak adduct in gill DNA of Mytilus galloprovincialis treated with benzo(a)pyrene. However, the mechanisms leading to DNA damage and the fate ofthe initial lesions in marine invertebrates exposed to genotoxic agents are still poorly understood
Persistence of DNA adducts and micronuclei in mediterranean mussels exposed to benzo[a]pyrene.
No full textDetection of micronuclei in gill cells and haemocytes of mussels exposed to benzo[a]pyrene.
No full textMediterranean mussels were exposed to benzo[a]pyrene for 2 days at doses which had previously caused the formation of specific adducts in gill DNA. Micronuclei and other nuclear abnormalities were detected in gill cells and haemocytes in order to ascertain the induction of cytogenetic damage in two different target cells in parallel. A number of procedural details were examined initially to improve the quality of slides obtained from mussel cells. Adequate cytological preparations were obtained when gill cells and haemocytes were suspended, respectively, in Alsever and sea water with EDTA, cytospun and fixed with absolute methanol. In the exposed mussels, micronuclei significantly increased in both the large gill cells (the main cell type) and the agranular haemocytes. Granular haemocytes, cells present in variable proportions between individual mussels, did not show cytogenetic damage except at the highest B[a]P doses. In the same slides, steady levels of binucleated cells were detected, whereas the incidence of other nuclear abnormalities was significantly higher in the exposed compared with control mussels. Precise knowledge of the replication kinetics of gill cells and haemocytes is still lacking
Effect of UV-irradiation on cell cycle checkpoints in human lymphocytes and in lymphoblastoid cells.
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ZmPIN1a and ZmPIN1b encode two novel putative candidates for polar auxin transport and plant architecture determination of maize
No full textShoot apical meristems produce organs in a highly stereotypic pattern that involves auxin. Auxin is supposed to be actively
transported from cell to cell by influx (AUXIN/LIKE AUXIN proteins) and efflux (PIN-FORMED proteins) membrane carriers.
Current hypotheses propose that, at the meristem surface, PIN proteins create patterns of auxin gradients that, in turn, create
patterns of gene expression and morphogenesis. These hypotheses are entirely based on work in Arabidopsis (Arabidopsis
thaliana). To verify whether these models also apply to other species, we studied the behavior of PIN proteins during maize
(Zea mays) development. We identified two novel putative orthologs of AtPIN1 in maize and analyzed their expression pattern
during development. The expression studies were complemented by immunolocalization studies using an anti-AtPIN1
antibody. Interestingly, the maize proteins visualized by this antibody are almost exclusively localized in subepidermal
meristematic layers. Both tassel and ear were characterized by a compact group of cells, just below the surface, carrying PIN. In
contrast to or to complement what was shown in Arabidopsis, these results point to the importance of internally localized cells
in the patterning process. We chose the barren inflorescence2 (bif2) maize mutant to study the role of auxin polar fluxes in
inflorescence development. In severe alleles of bif2, the tassel and the ear present altered ZmPIN1a and ZmPIN1b protein
expression and localization patterns. In particular, the compact groups of cells in the tassel and ear of the mutant were missing.
We conclude that BIF2 is important for PIN organization and could play a role in the establishment of polar auxin fluxes in
maize inflorescence, indirectly modulating the process of axillary meristem formation and development
"Modeled microgravity" affects cell response to ionizing radiation and increases genomic damage
No full textThe aim of this work was to assess whether "modeled microgravity" affects cell response to ionizing radiation, increasing the risk associated with radiation exposure. Lymphoblastoid TK6 cells were irradiated with various doses of gamma rays and incubated for 24 h in a modeled microgravity environment obtained by the Rotating Wall Vessel bioreactor. Cell survival, induction of apoptosis and cell cycle alteration were compared in cells irradiated and then incubated in 1g or modeled microgravity conditions. Modulation of genomic damage induced by ionizing radiation was evaluated on the basis of HPRT mutant frequency and the micronucleus assay. A significant reduction in apoptotic cells was observed in cells incubated in modeled microgravity after gamma irradiation compared with cells maintained in 1g. Moreover, in irradiated cells, fewer G2-phase cells were found in modeled microgravity than in 1g, whereas more G1-phase cells were observed in modeled microgravity than in 1g. Genomic damage induced by ionizing radiation, i.e. frequency of HPRT mutants and micronucleated cells, increased more in cultures incubated in modeled microgravity than in 1g. Our results indicate that modeled microgravity incubation after irradiation affects cell response to ionizing radiation, reducing the level of radiation-induced apoptosis. As a consequence, modeled microgravity increases the frequency of damaged cells that survive after irradiation
Analysis of mutational effects at the HPRT locus in human G0 phase lymphocytes irradiated in vitro with gamma rays.
No full textThe mutational effects of ionising radiation at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus were studied in human peripheral blood G(0) phase lymphocytes irradiated in vitro with gamma rays. The presence of radiation induced mutants was assessed by selecting the HPRT mutants every week on the basis of 6-thioguanine resistance up to 1 month after irradiation. A dose-related increase of 14.25x10(-6) mutants/Gy was measured after an expression time of 7 days. After 2 weeks from culture starting the fraction of clonable cells in irradiated and control cell populations decreased, limiting the measurements of mutant frequency. The mutational spectrum of the HPRT gene was determined by PCR analyses in a total of 99 mutant clones derived from irradiated lymphocytes. The independent origin of mutant clones carrying the same mutation was assessed by analysing the TCR gamma gene rearrangements. The results showed a dose-related increase of deletion mutants up to 3Gy, whereas point mutation frequency increased only up to 2Gy. Two preferentially deleted regions were identified; one involving the HPRT exon 3, and another one the 3'-terminal and the 3'-flanking region of the gene. One complex mutation involving a non-contiguous deletion of exons 2-5 and 7/8 was observed among the mutants isolated after 3Gy irradiation
Alterazione del ciclo cellulare e induzione di apoptosi in cellule linfoidi umane irradiate con UVC e radiazioni gamma
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