Microbial dechlorination of polychrolinated biphenyls

Polychlorinated biphenyls (PCBs) are organic xenobiotics contaminating environment for at least 50 years. They could be eventually eliminated by various organisms under different conditions. The degree of chlorine substitution per biphenyl molecule influences biodegradability which decreases with increasing chlorination. Our work is focused on the PCBs biodegradation under anaerobic conditions. The suitable high chlorinated biphenyls are converted via reductive dechlorination to the chlorinated biphenyls with lower extent of chlorine, which could be eventually fully mineralized by aerobic bacteria. Microbial consortium was isolated from sediment of Strážský Creek (located near by plant producing PCBs in the past). This consortium was able to dechlorinate polychlorinated biphenyls under anoxic conditions. The effectiveness of this process was tested under different cultivation condition – different energetic sources (Aroclor 1248 or Aroclor 1260 or Delor 103 or Delor 106), addition of potential electron donors (pyruvate, lactate or acetate with hydrogen) and further if there is necessary to add yeast extract into fresh low sulphur cultivation media. Our microbial consortia so far do not need supplementation by non-contaminated sediment to maintain dechlorination activity. Addition of yeast extract is non essential, but needs to be further proved in serial transfers. In all cases (except acetate without yeast extract) dechlorination proceeds at meta- and flanked paraposition.

Determination of multi-residue PCBs in air by real-time fluorescent quantitative immuno-PCR assay

Amplification curves of a dilution series of Aroclor 1248 of direct competition rt-IPCR. In the figure, the fluorescence signal of the curve (10 fg mL−1) reaching the threshold was at around cycle 12.3, and there was a fall in the Ct value from 10 to 106 fg mL−1. This result implied that the time expended to reach the threshold for the high concentration of PCB molecules was much longer than for the low concentration PCBs.

The effect of PCB126, 77, and 153 on the intracellular mobilization of Ca+2 in bovine granulosa and luteal cells after FSH and LH surge in vitro

Polychlorinated biphenyls (PCBs) are a group of persistent environmental pollutants that impair cattle reproduction. Among other effects, PCBs can disturb the intracellular mobilization of Ca+2 in several cell types. Hence, it is possible that they disrupt the transduction of intracellular signals generated from gonadotropin (FSH/LH) receptors. In steroidogenic ovarian cells, a defect in Ca+2 mobilization may have a detrimental influence on two important processes: the secretion of steroids (E2 or/and P4) and their morphological and functional differentiation. The aim of this study was to determine the influence of PCBs: 126 (dioxin-like) 77 (ambivalent) and 153 (estrogen-like) and a mixture of PCBs (Aroclor 1248) on these processes. Bovine granulosa and luteal cells were incubated for 72 hrs with PCBs (100 ng/ml), followed by Fura 2AM dye, and the fluctuations in intracellular Ca+2 mobilization after FSH/LH treatment were determined using an inverted microscope coupled with a CCD camera. The intensity and area of fluorescence excited by UV light were detected in the green spectrum of visible light. Aroclor 1248 and PCBs 153 and 77 significantly decreased (P < 0.01-0.001) the effect of FSH on intracellular Ca+2 mobilization in granulosa cells. In luteal cells, the most effective PCB on this process was PCB 77. The results revealed adverse effects of PCBs on the mobilization of intracellular Ca+2. Moreover, the estrogen- like congeners were found to more effectively disturb this process than the dioxin-like PCB 126. Hence, it is possible for PCBs to have a negative influence on reproductive processes by affecting calcium mobilization.

Effect of polychlorinated biphenyls (Aroclor-1248) on the secretory function of bovine luteal cells affected by LH, noradrenaline and high density lipoproteins

The corpus luteum (CL), formed from the ruptured follicle, is required for the course of normal cyclicity and the duration of pregnancy in females. The influence of a mixture of polychlorinated biphenyls &ndash; PCBs (Aroclor-1248) &ndash; on the secretory function of CL (dispersed bovine luteal cells) during different stages of the estrous cycle was studied. The cells (1.2 &times; 105/ml) were pre-incubated for 24 h and were then treated with 10, 100 or 500 ng/ml of PCBs. A􀄞er 24, 48, 72, 96 or 144 h luteinizing hormone (LH; 100 ng/ml; positive control) was added to the medium. The most evident impaired secretion of progesterone was measured after 72 h of incubation with PCBs and this time was selected for the further experiments. In Exp. 2 high density lipoproteins (HDL), as a source of cholesterol (25 &mu;g), increased progesterone secretion from luteal cells; PCBs enhanced this effect in mid and late stage of the estrous cycle. PCBs had no effect on the stimulatory influence of LH, which itself stimulated progesterone secretion. In Exp. 3 PCBs (500 ng/ml) decreased progesterone secretion from the early CL and increased stimulatory effect of noradrenaline (NA) on progesterone secretion from mid CL. Aroclor-1248 stimulated oxytocin (OT) secretion from all stages of CL development. NA alone increased OT secretion from mid and late CL and moreover, it amplified effect by Aroclor on CL from all studied stages of their development. We conclude that the mixture of PCBs, commercially available as Aroclor-1248, can directly impair the function of bovine CL and thus it can affect the estrous cycle duration or embryo development.

Influence of polychlorinated biphenyls (PCBs) and phytoestrogens on prostaglandin F2α and E2secretion from bovine endometrial cells at a postovulatory stage of the estrous cycle

Polychlorinated biphenyls (PCBs) and phytoestrogens were found to affect contractions of bovine uterus. Prostaglandins (PG) F₂_&aacute; and E₂ are also involved in the uterine contractility. Hence the aim of these studies was to investigate the effect of PCBs and some phytoestrogens on PG secretion from endometrial cells obtained on days 1&ndash;5 of the oestrous cycle. Cells were incubated in aerated atmosphere at 38&deg;C for 24 h, separately with the mixture of PCBs &ndash; Aroclor 1248 (10 ng/ml), with individual congeners -77, -126 or -153 (each at the dose 100 &nbsp;g/ml), coumestrol, daidzein or genistein (each at the dose 10^&ndash;6M) or jointly each PCB with each of the phytoestrogens. Using the TOX1-kit neither Aroclor 1248 (Ar 1248) nor individual congeners were found to affect the viability of cells compared to the control (P &gt; 0.05). All used PCBs markedly increased the metabolite of PGF₂_&aacute;(PGFM) concentrations (P &lt; 0.05) but not PGE₂(P &gt; 0.05). Hence the ratio of PGF₂_&aacute; to PGE₂ was also increased by PCBs. However, when these cells were incubated with each of the phytoestrogens, there was a decrease in both PGF₂_&aacute; and PGE₂ secretion compared to the control (P &lt; 0.05) but without altering the PGF₂_&aacute; : PGE₂ ratio. Moreover, phytoestrogens could clearly reduce the concentrations of PGFM elicited by PCBs, and they reduced PGE₂ secretion compared to that evoked by PCB-126 and &ndash;153 only. Thus phytoestrogens can restore the proper ratio of PGF₂_&aacute; : PGE₂ secreted by the bovine endometrium.