Eutrophication with a large number of Microcystis aeruginosa commonly occurs worldwide, thereby threatening the aquatic ecosystem and human health. In this study, four kinds of algicides were tested to explore their influence on cell density and chlorophyll-a of M. aeruginosa. Results showed that aluminum silicate agent, which inhibited more than 90% cell growth compared with the control group, demonstrated the strongest inhibition effect immediately on M. aeruginosa growth. Furthermore, the production and release of microcystin (MC)-LR were investigated. Aluminum silicate, CuSO4, and Emma-11 were more effective than pyrogallic acid in disrupting the cells of M. aeruginosa, thereby increasing the extracellular MC-LR concentration. Aluminum silicate caused the highest extracellular MC-LR concentration of more than 45 mg·L–1. Biotoxicity was also detected to evaluate the environmental risks of MC-LR release, which were related to the usages of different algicides. Extracellular MC-LR concentration mostly increased when the biotoxicity of algae solution increased. The experiments were also designed to reveal the effects of physical conditions in riverways, such as natural sunlight, aeration and benthal sludge, on MC-LR degradation. These findings indicated that UV rays in sunlight, which can achieve a MC-LR removal efficiency of more than 15%, played an important role in MC-LR degradation. Among all the physical pathways of MC-LR removal, benthal sludge adsorption presented the optimal efficiency at 20%.
Arsenic is a significant environmental concern worldwide, primarily due to geo physiochemical contamination of drinking water, and a major public health hazard in both developing and developed countries. The present study was aimed to investigate ameliorative effects of curcumin (Cur) against sodium arsenite (SA)-induced toxicity in cultured murine Sertoli cells. The cells were treated with SA (5 μM) and Cur (5 μg/ml and 10 μg/ml) alone or in combination for 12 hr. The SA treatment decreased cell viability, produced oxidative stress, and induced apoptosis as reflected by reactive oxygen species (ROS) generation, loss of mitochondrial transmembrane potential, DNA fragmentation, and apoptotic cells. Moreover, the SA-induced cell cycle arrest in the cells is characterized by a rise in the number of cells in the sub G1 phase of the cell cycle. The Cur was found to be effective in reversing all these arsenic (As)-induced cellular events. Data suggest that Cur modulates As-mediated oxidative stress, apoptosis, DNA fragmentation, and cell cycle arrest through suppression of excessive ROS generation. Evidence indicates that Cur may emerge as a useful protective agent against As-induced Sertoli cells toxicity by inhibiting As-induced damage in testes. 相似文献
Gymnodinium nagasakiense is a noxious red tide dinoflagellate often associated with damage to fisheries in Japan. DNA synthesis and the cell cycle in this organism were investigated from 1989 to 1990 by determining relative DNA contents of individual cells using an epifluorescence microscopy-based microfluorometry system. The nuclei were stained with the DNA-specific fluorochrome 4-6-diamidino-2-phenylindole (DAPI). Because photosynthetic pigment interferes with the fluorescence from the DAPI-DNA complex, the pigment was eliminated by methanol treatment as a first step in quantitative microfluorometry. Nuclear DNA contents, cell size distribution, cell density, and frequency of paired cells were determined every 2h for 24h using cells grown on a 12h light:dark cycle. DNA synthesis and cell division were tightly phased to a particular period of the light:dark cycle. DNA synthesis (S phase) occurred from 10:00 to 22:00 hrs and was followed by cytokinesis. The presence of such a distinct S phase strongly suggests thatG. nagasakiense has a typical eukaryotic cell cycle. This type of cell cycle makes it possible to estimate speciesspecific in situ growth rate based on the diel pattern of DNA synthesis. 相似文献
Humans are primarily exposed to fluoride (Fl), a widespread environmental pollutant, via contaminated drinking water and foodstuffs. The aim of this study was to examine whether sodium fluoride (NaF) exerted cytotoxic effects in human hepatocarcinoma (HepG2) cells. HepG2 cells were incubated with different concentrations of NaF and reactive oxygen species (ROS) levels, cell cycle, apoptosis, and DNA damage determined. Concentration-dependent studies showed that exposure to HepG2 cells with different concentrations of NaF for 24 hr significantly decreased cell viability and intracellular antioxidant capacity. Furthermore, NaF exposure increased lipid peroxidation levels and accumulation of intracellular ROS; and lowered antioxidant glutathione concentrations. In addition to oxidative impairments, NaF treatment enhanced HepG2 cell death via apoptotic pathway as evidenced by DNA fragmentation and cell cycle arrest. Sodium fluoride treatment unregulated p53 level, and Bax and Bcl2 expression. Diminished cell viability and changes in cell cycle accompanied a rise in p53 expression. 相似文献
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) contents were measured daily during the zoeal development of the crab Rhithropanopeus harrisii (Gould). DNA concentration (per unit protein) decreased as larvae increased in size. Total DNA content per larva showed an abrupt increase at the second molt and increased steadily during the third and fourth zoeal stages. Ratios of fresh weight to DNA were highest during the first two zoeal stages, dropped sharply at the second molt, then increased during the third and fourth zoeal stages. RNA:DNA ratios showed cyclical activity apparently related to the molt cycle. Assuming that fresh weight: DNA ratio reflects cell size and that DNA content reflects cell number, growth during the first two stages is due primarily to increase in cell size and during the last two stages to a combination of increase in cell size and number. Assuming further that RNA:DNA ratios reflect protein-synthesis activity, such activity in these larvae follows a rhythm related to the molt cycle. 相似文献
The presence of cyanobacterial toxins in drinking and recreational waters represents a potential risk to public health. Microcystin-LR (MC-LR) is a potent cyclic heptapeptide hepatotoxin produced by the blue-green alga Microcystis aeruginosa. Chemoprotectant studies suggest that membrane-active antioxidants may offer a protection against microcystin toxicity. The aim of this study is to investigate the potential benefits of dietary supplementation of lycopene as antioxidants on microcystin toxicity in mouse liver. A group of Balb/c was pre-treated for 2 weeks with lycopene (10 mg/mouse/d) before an intraperitoneal injection (i.p.) of MC-LR. The potential benefits of lycopene were evaluated based on lipid peroxidation, alanine transaminase (ALT), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) levels. Therefore, lycopene supplied as a dietary supplement may have a protective effect against chronic exposure to MC-LR. 相似文献
A promising bacterial strain for biodegrading microcystin-LR (MC-LR) as the sole carbon and nitrogen source was successfully isolated from Lake Dianchi, China. The strain was identified as Sphingopyxis sp. USTB-05, which was the first isolated MCs-biodegrading Sphingopyxis sp. in China. The average biodegradation rate of MC-LR by Sphingopyxis sp. USTB-05 was 28.8 mg??L?1 per day, which was apparently higher than those of other bacteria reported so far. The optimal temperature and pH for both strain USTB-05 growth and MC-LR biodegradation were 30??C and 7.0, respectively. The release of MC-LR from the cyanobacterial cells collected from Lake Guishui and the biodegradation of MC-LR by both strain and cell-free extract (CE) were investigated. The results indicated that MC-LR with the initial concentration of 4.0 mg??L?1 in water was biodegraded by Sphingopyxis sp. USTB-05 within 4 d, while MC-LR with the initial concentration of 28.8 mg??L?1 could be completely removed in 3 h by CE of Sphingopyxis sp. USTB-05 containing 350 mg??L?1 protein. During enzymatic biodegradation of MC-LR, two intermediate metabolites and a dead-end product were observed on an HPLC chromatogram. Moreover, the similar scanning profiles of MC-LR and its metabolic products indicate that the Adda side-chain of MC-LR was kept intact in all products. 相似文献
Profiles of diarrhetic shellfish poisoning (DSP) toxins produced throughout the growth cycle and the cell cycle of the toxigenic
marine dinoflagellate Prorocentrum lima were studied in triplicate unialgal batch cultures. Cells were pre-conditioned at 18 ± 1 °C, under a photon flux density
(PFD) of 90 ± 5 μmol m−2 s−1 on a 14 h light:10 h dark photoperiod. In exponential growth phase, cultures were synchronized in darkness for 17 d. After
dark synchronization, cultures were transferred back to the original photoperiod regime. Cells were harvested for DSP toxin
analysis by LC-MS (liquid chromatography with mass spectrometry), and double-stranded (nuclear) DNA was quantified by flow
cytometry. The cell populations became asynchronous within approximately 3 d after transition from darkness to the 14 h light:10 h
dark photoperiod. This may be due to the prolonged division cycle (5 to 7 d) that is not tightly phased by the photoperiod.
Unlike other planktonic Prorocentrum spp., cytokinesis in P. lima occurred early in the dark and ceased by “midnight”. Cellular levels of the four principal DSP toxins, okadaic acid (OA),
OA C8-diol-ester (OA-D8), dinophysistoxin-1 (DTX1) and dinophysistoxin-4 (DTX4), ranged from 0.37 to 6.6, 0.02 to 1.5, 0.04
to 2.6, and 1.8 to 7.8 fmol cell−1, respectively. No toxin production was evident during the extended period of dark synchronization nor during the initial
period when NH4 was consumed as the major nitrogen source. Soon after the cells were returned to the 14 h light:10 h dark cycle and they
began to take up NO3, cellular levels of all four toxins gradually increased. This increase in DSP toxins usually occurred in the light, marked
by a rise in DTX4 levels that preceded an increase in the cellular concentration of OA and DTX1 (delayed by 3 to 6 h). Thus,
DTX4 synthesis is initiated in the G1 phase of the cell cycle and persists into S phase (“morning” of the photoperiod), whereas
OA and DTX1 production occurs later during S and G2 phases (“afternoon”). No toxin production was measured during cytokinesis,
which happened early in the dark. The evidence indicates that toxin synthesis is restricted to the light period and is coupled
to cell cycle events.
Received: 3 September 1998 / Accepted: 30 March 1999 相似文献
Inhibition of photosystem II (PSII) activity by atrazine was investigated in the green alga Chlamydomonas reinhardtii during different states of the cell cycle. The algal cultures were maintained under continuous light or under light/dark cycle (16/8?h) to obtain homogenized cell cycle distribution. The cycle state of algal population was determined by the DNA content using flow cytometry and defined as newly divided cells before the initiation of DNA replication (G0/G1) and cells at the end of the replication cycle with fully duplicated DNA content (G2/M). Under different synchronized states of the cell population, the photosynthetic activity was investigated after treatment at 10, 100, and 1000?µmol?L?1 atrazine exposed for 24?h by using fluorescence parameters related to PSII activity measured with a plant efficiency analyzer and pulse-amplitude modulated methods. In this study, we found that the atrazine effect was different depending on cell cycle phases and the period of illumination. Algal cells under light–dark cycle showed inhibition of the PSII electron transport leading to an increase of heat energy dissipation by the PSII reaction center. Algal cells grown under continuous light was shown to be more resistant to atrazine than the cells grown under light–dark cycle. 相似文献
ABSTRACTLead (Pb) is one of the most toxic heavy metals that affect the physiological status of aquatic organisms. The present investigation evaluated the possible toxic effect of lead chloride (PbCl2) on biomarkers responses, DNA damage and histological alterations in Venus verrucosa gills and digestive gland. Three concentrations of PbCl2 (D1:1µgL?1, D2: 10µgL?1 and D3: 100µgL?1) were chosen for V. verrucosa exposure during six days. At the end of the trial, it was found that Pb tended to accumulate in both gills and digestive gland in a dose-dependent manner. However, gill tissues exhibited the highest metal burden. Our results showed an increase of malondialdehyde, protein carbonyls and advanced oxidation protein product levels in both organs following PbCl2exposure. The induction of both non-enzymatic and enzymatic antioxidant systems; as well as the decrease of the acetylcholinesterase activity and degradation of DNA structure was recorded in the gills and digestive gland. The histopathological alterations observed in gills (disruption of lamellas and cilia filaments?…) and digestive gland (lumens occlusion, necrosis and fibrosis) confirmed the aforementioned results. Our data highlighted the short-term toxicity effects of PbCl2 on V. verrucosa and pointed out a high sensitivity of gills towards this metal. 相似文献
The molecular basis of male reproduction for cross-regulation between androgen and thyroid hormone axes is still rudimentary. This study aims to define a possible mechanism of hypothyroidism-induced reproductive influence with respect to sex hormone, mineral, sperm motility, oxidative stress, c-Fos expression, cell cycle, and apoptosis in rat testes. The Wistar rats were randomly divided into control group (NS) and hypothyroidism group [1 ml/100g BW/day, 0.1% propylthiouracil (PTU)] by intragastric gavage for 60 days. Blood samples were collected to measure the serum levels. The epididymis was excised to measure sperm motility and testes were excised to measure mineral, oxidative stress, c-Fos expression, cell cycle, and apoptosis. After 60 days, body weight, relative testes weight, triiodothyronine, and total thyroxine were all significantly decreased, whereas thyroid stimulating hormone was increased in the hypothyroidism group. A significant increase in sex hormone level of estradiol (E2) and significant decreases in testosterone (T) and T/E2 ratio were observed following PTU treatment. And sperm quality was also significantly changed. There were significant decreases in the contents of calcium (Ca2+) and zinc (Zn2+). On the other hand, malondialdehyde and hydrogen peroxide contents significantly increased, whereas the activity of superoxide dismutase, catalase and nitric oxide synthase and nitric oxide content significantly decreased in hypothyroid rats. The mRNA and protein expressions of c-Fos decreased significantly. The cell percentage in G0/G1 phase increased significantly, whereas decreased significantly in S and G2/M phases. Also, a significant increase in testicular cell apoptosis was observed in hypothyroid-treated rats. These results suggested that hypothyroidism could affect reproductive function in the form of changed sex hormone levels, sperm motility and testicular Ca2+ and Zn2+, and enhanced oxidative stress leading to c-Fos abnormal expression and increased apoptosis. 相似文献
Epigenetic change is a key factor for esophageal cancer progression. This study shows that upon exposure of primary cultures of human esophageal epithelial cells obtained from people of the Kazakh nationality in China to N-methyl-N′-nitro-N-nitrosoguanidine at concentrations of 0.75, 1.50, and 3.00 mg/L, (1) cell proliferation was inhibited, the percentages of cells in the G0 and G1 phases declined, and those in the S and G2 + M phases increased at all concentrations, while apoptosis rates increased at medium and high concentrations; (2) the content of DNA-methyltransferases 3a and 3b and the activities of DNA-methyltransferase 1 and DNA-methyltransferase 3a increased at all concentrations while the content of DNA-methyltransferase 1 and the activity of DNA-methyltransferase 3b were increased only at the high concentration; (3) messenger RNA and protein levels of DNA-methyltransferases 1, 3a, and 3b were increased at all concentrations. Obviously, N-methyl-N′-nitro-N-nitrosoguanidine in the low mg/L range can inhibit the proliferation of normal Kazakh esophageal epithelial cells, can cause cell cycle arrest in the S and G2 + M phases, promote apoptosis, and increase the activities of DNA-methyltransferases 1, 3a, and 3b. 相似文献
The spider crabHyas araneus (L.) was collected from the North Sea in winter 1986–1987 and reared in the laboratory from hatching of the Zoea I (ZI) through the first juvenile instar (CI). Within a given moult cycle, individuals of the same age were sampled in intervals of 2 (ZI, ZII, CI) or 3 d (megalopa) for analysis of dry weight (W), carbon (C), nitrogen (N), hydrogen (H), protein, DNA, and RNA. Lipid was calculated from C. Biomass, growth rate and nucleic acid contents showed high variability during each moult cycle and between instars. Instantaneous growth rates of C were high in postmoult and intermoult, and low in the premoult period of each moult cycle. A shift was observed from high rates of lipid accumulation in the postmoult and intermoult stages to proportionally increasing protein accumulation during late premoult (ZI), or throughout a major part of the remaining moult cycle (in all other instars). DNA was accumulated throughout the ZI and ZII instars, but decreased in late premoult megalopa. It increased again from late intermoult through intermediate premoult in juveniles. RNA increased continuously during ZI and ZII, and decreased in the megalopa, almost to levels that had been found immediately after hatching. In juveniles, variation in RNA followed closely those in DNA. Cell multiplication (expressed by DNA increase) dominated over increase in cell size (defined by the C/DNA ratio) during the zoeal instars and in postmoult through early intermoult in the megalopa and CI. When specific (C-related) RNA values and RNA/DNA ratios were compared with instantaneous growth rates in C and N, no general correspondence was detected. The only significant relationship between specific RNA values and instantaneous C or N growth rates was found in the megalopa. The same held for the relationship between the RNA/DNA ratio and growth. Here, in addition to the megalopa, a correspondence with C growth was also found in the CI instar. Our results suggest that variation in nucleic acids may provide useful insights into mechanisms of growth on the cellular level (cell multiplication vs cell enlargement). However, lack of general correlation with variation in growth rates ofH. araneus larvae shows that the use of nucleic acids as a measure of growth is probably based upon too simplistic assumptions; it may not yield reliable predictions, when growth is associated with developmental events. 相似文献