Relationships between riverine and terrestrial dissolved organic carbon: Concentration, radiocarbon signature, specific UV absorbance.

The transfer of dissolved organic carbon (DOC) from land to watercourses plays a major role in the carbon cycle, and in the transport and fate of associated organic and inorganic contaminants. We investigated, at global scale, how the concentrations and properties of riverine DOC depend upon combinations of terrestrial source solutions. For topsoil, subsoil, groundwater and river solutions in different Köppen-Geiger climatic zones, we compiled published and new values of DOC concentration ([DOC]), radiocarbon signature (DO14C), and specific UV absorbance (SUVA). The average value of each DOC variable decreased significantly in magnitude from topsoil to subsoil to groundwater, permitting the terrestrial sources to be distinguished. We used the terrestrial data to simulate the riverine distributions of each variable, and also relationships between pairs of variables. To achieve good matches between observed and simulated data, it was necessary to optimise the distributions of water fractions contributed by each of the three terrestrial sources, and also to reduce the mean input terrestrial [DOC] values, to about 60% of the measured ones. One possible explanation for the required lowering of the modelled terrestrial [DOC] values might be unrepresentative sampling of terrestrial DOC, including dilution effects; another is the loss of DOC during riverine transport. High variations in simulated riverine DOC variables, which match observed data, are due predominantly to variations in source solution values, with a lesser contribution from the different combinations of source waters. On average, most DOC in rivers draining catchments with forest and/or grass-shrub land cover comes in similar amounts from topsoil and subsoil, with about 10% from groundwater. In rivers draining croplands, subsoil and groundwater solutions are the likely dominant DOC sources, while in wetland rivers most DOC is from topsoil.

A novel approach to baseline water quality assessment at local and catchment scale: a case study from Berambadi, India.

Optimal design and maintenance are necessary for the sustainability of wastewater treatment systems. In this study, we present the outcome of a novel approach to baseline assessment conducted prior to the design and deployment of a decentralized wastewater treatment system at a school in rural India. The baseline water quality monitoring protocol was deployed to assess (a) the quality and quantity of wastewater (greywater and blackwater) flows from the school and (b) the status of surface water and groundwater quality in the catchment. Hourly greywater flows and water quality trends were monitored across four seasons at the school. Average freshwater consumption at the school was 518 ± 322 L/day for hand washing and 287 ± 97 L/day for cooking meals. Greywater generation showed high hourly variations in COD levels. Greywater generated from hand wash and kitchen sources contributed to 110 g/day and 96 g/day of BOD5 respectively and 214 g/day and 141 g/day of COD respectively. Based on additional data from a self-reporting sanitation survey, the organic contaminant load generated from the toilet was estimated to be 1.5 ± 0.1 kg COD/day. At the catchment scale, both groundwater and surface water quality were monitored seasonally to assess the impact of raw sewage and stormwater inputs. Compared with borewells, high nitrate-N levels (> 10 mg/L) were observed in the village hand pump samples throughout the year. Maximum nitrate-N (16 mg/L) and fecal coliforms (3.9 log MPN/100 mL) levels were observed in surface waters during monsoons, indicating the impact of sewage and surface runoff on water quality. The proposed approach is useful to estimate data on freshwater use and wastewater generation at the school and hence to make the case for, and design of, a sustainable water management intervention.

Sustainable water resources through harvesting rainwater and the effectiveness of a low-cost water treatment.

Increases in world population and climate change are some of the pressures affecting water resources for current and future water availability. The variability in water availability can reduce agricultural yields, food supplies and potentially leads to malnutrition and spread of diseases in water-poor countries. Even some water-rich countries can experience prolonged periods of dry weather, causing a drop in water reservoirs levels, forcing more restricted water resources management. Rainwater harvesting is one key option in adapting to water shortage and future demands that may alleviate the pressure on existing water resources. This work evaluates a roof top rainwater harvesting system (RWHS) installed as part of a decentralised wastewater treatment system designed to enable a circular economy by providing a more reliable water supply system in a remote public school in rural India. The effectiveness of the RWHS in reducing the pressure on a groundwater supply was assessed along with the physical, chemical and microbial characteristics of the stored rainwater over time. Further, the application of a low-cost primary treatment to make the harvested water safe to use for multiple purposes was investigated. The results revealed that the harvested water was of acceptable quality at the start of collection, however, microbial abundance increased when the rainwater was stored for a long time without treatment. Thus, a chlorine dosing regimen for the RWHS was designed based on laboratory and field experiments. The results also demonstrated that the low-cost chlorination process was effective in the field in reducing microbial abundance in the stored water for more than 30 days. However, as the residual chlorine level was reduced with time to <0.2 mg/l in the storage vessel, the microbial abundance increased, albeit to a much lower level that meets the Indian bathing water standards. The results provide evidence that installed RWHS has reduced the pressure on existing water supply at the school by up to 25% of the water that used for washing and flushing with no treatment, and with regular chlorination, greater savings and multiple uses of the stored rainwater can be achieved.

Potash fertilizer promotes incipient salinization in groundwater irrigated semi-arid agriculture.

Incipient groundwater salinization has been identified in many arid and semi-arid regions where groundwater is increasingly used for irrigation, but the dominant processes at stake in such context are yet uncertain. Groundwater solutes originates from various sources such as atmospheric inputs, rock dissolution and fertilizer residues, and their concentration is controlled by hydrological processes, in particular evapotranspiration. Here, we propose a deconvolution method to identify the sources and processes governing the groundwater Chloride concentration in agricultural catchments, using the relative variations of Sodium and Chloride and using a neighbouring pristine catchment as a reference for the release rate of Na by weathering. We applied the deconvolution method to the case of the Kabini Critical Zone Observatory, South India, where groundwater was sampled in 188 farm tubewells in the semi-arid catchment of Berambadi and in 5 piezometers in the pristine catchment of Mule Hole. In Berambadi, groundwater composition displayed a large spatial variability with Cl contents spanning 3 orders of magnitude. The results showed that the concentration factor due to evapotranspiration was on average about 3 times more than in the natural system, with higher values in the valley bottoms with deep Vertisols. Linked with this process, large concentration of Chloride originating from rain was found only in these areas. At the catchment scale, about 60 percent of the Chloride found in groundwater originates from fertilizer inputs. These results show that Potassium fertilization as KCl is an important source of groundwater salinization in semi-arid context, and stress that identifying dominant drivers is crucial for designing efficient mitigation policies.

An Assessment of the Performance of the PLUS+ Tool in Supporting the Evaluation of Water Framework Directive Compliance in Scottish Standing Waters.

Phosphorus is one of the main causes of waterbodies in Scotland being at less than good ecological status (GES) in terms of the water framework directive (WFD). In Scotland, there are more than 8000 standing waters, defined as lakes and reservoirs that have a surface area of more than 0.5 km2. Only about 330 of these are monitored routinely to assess compliance with the WFD. The export coefficient tool PLUS+ (phosphorus land use and slope) has been developed to estimate total phosphorus (TP) concentrations in the unmonitored sites; modelled values are then compared to WFD target concentrations for high, good, moderate, poor, and bad status to assess compliance. These type-specific or site-specific targets are set by the regulatory authority and form part of a suite of physical, chemical, and ecological targets that are used to assess GES, all of which must be met. During development, the PLUS+ tool was applied to 323 monitored catchments and 7471 unmonitored catchments. The efficacy of the tool was assessed against TP concentrations observed in 2014 and found to perform well in the rural catchments. 51% of standing waters had the same modelled and observed WFD class (i.e., High, Good, Moderate, Poor, Bad), and a further 40% of standing waters had a modelled WFD class that was within one class of observed water quality. The tool performed less well in catchments with larger inputs of TP from urban sources (e.g., sewage). The greatest deviations between measured and modelled classes were explained by the shortage of information on wastewater treatment works, fish farms, migratory birds, levels of uncertainty in TP measurements, and the amount of in-lake re-cycling of P. The limitations of the tool are assessed using data from six well documented case study sites and recommendations for improving the model performance are proposed.

Impacts of nitrogen deposition on carbon and nitrogen cycling in alpine Racomitrium heath in the UK and prospects for recovery.

Deposition of reactive nitrogen (N) is a major threat to terrestrial ecosystems associated with impacts on ecosystem properties and functions including carbon (C) and nutrient stocks, soil water quality and nutrient retention. In the oceanic-alpine Racomitrium heath habitat, N deposition is associated with moss mat degradation and a shift from bryophyte to graminoid dominance. To investigate the effects of moss mat decline on C and N stocks and fluxes, we collected Racomitrium heath vegetation/soil cores from sites along a gradient of N deposition in the UK. Cores were maintained under controlled conditions and exposed to scenarios of current (8-40 kg N ha-1 y-1), reduced (8 kg N ha-1 y-1) and elevated (50 kg N ha-1 y-1) N deposition. Cores from high N deposition sites had smaller aboveground C and N stocks and, under current conditions, leached large amounts of inorganic N and had low soil water pH compared with low N deposition sites. With reduced N deposition there was evidence for rapid recovery of soil water quality in terms of reduced N leaching and small increases in pH. Under high N deposition, cores from low N deposition sites retained much of the applied N while those with a history of high N deposition leached large amounts of inorganic N. Carbon fluxes in soil water and net CO2 fluxes varied according to core source site but were not affected by the N deposition scenarios. We conclude that C and N stocks and cycling in Racomitrium heath are strongly affected by long-term exposure to N deposition but that soil water quality may improve rapidly, if N deposition rates are reduced. The legacy of N deposition impacts on moss mat cover and vegetation composition however, mean that the ecosystem remains sensitive to future pulses in N input.

Dynamic Modeling and Target Loads of Sulfur and Nitrogen for Surface Waters in Finland, Norway, Sweden, and the United Kingdom.

The target load concept is an extension of the critical load concept of air pollution inputs to ecosystems. The advantage of target loads over critical loads is that one can define the deposition and the point in time (target year) when the critical (chemical) limit is no longer violated. This information on the timing of recovery requires dynamic modeling. Using a well-documented dynamic model, target loads for acidic deposition were determined for 848 surface waters across Finland, Norway, Sweden, and the United Kingdom for the target year 2050. In the majority of sites ( n = 675), the critical ANC-limit was predicted to be achieved by 2050; however, for 127 sites, target loads were determined. In addition, 46 sites were infeasible, i.e., even a reduction of anthropogenic deposition to zero would not achieve the limit by 2050. The average maximum target load for sulfur was 38% lower than the respective critical load across the study lakes ( n = 127). Target loads on a large regional scale can inform effects-based emission reduction policies; the current assessment suggests that reductions beyond the Gothenburg Protocol are required to ensure surface water recovery from acidification by 2050.

Citizen science evidence from the past century shows that Scottish rivers are warming.

Salmonid species are highly sensitive to river water temperature. Although long-term river temperature monitoring is essential for assessing drivers of change in ecological systems, these data are rarely available from statutory monitoring. We utilized a 105-year citizen science data set of river water temperature from the River Spey, North-East Scotland, gathered during the fishing season (April-October) between 1912 and 2016. As there were gaps in the records we applied generalised additive models to reconstruct long-term daily river temperature in the fishing season from air temperature, cumulative air temperature, day length and runoff. For that, continuous hydrometeorological data have been obtained from statutory monitoring and process-based models. Long-term warming trends of river temperature, namely an increase of 0.2 K per decade after 1961, have been mostly related to increasing air temperature of the same magnitude. Indirect impacts of rising air temperatures include less snow accumulation and snow melt as well as earlier snow melt. The snow free period starts around 2 days earlier per decade throughout the study period and 7 days earlier per decade after 1965. Consequently, the contribution of snow melt and its cooling properties to river temperature in spring are declining. Citizen science delivered a data set that filled a vital knowledge gap in the long-term historical assessment of river temperatures. Such information provides a robust basis for future assessments of global change and can help inform decision-makers about the potential importance of enhancing the resilience of rivers and aquatic ecology to climate change.

Long-term macronutrient stoichiometry of UK ombrotrophic peatlands.

In this paper we report new data on peat carbon (C), nitrogen (N) and phosphorus (P) concentrations and accumulation rates for 15 sites in the UK. Concentrations of C, N and P measured in peat from five ombrotrophic blanket mires, spanning 4000-10,000years to present were combined with existing nutrient data from ten Scottish ombrotrophic peat bogs to provide the first UK perspective on millennial scale macronutrient concentrations in ombrotrophic peats. Long-term average C, N and P concentrations (0-1.25m) for the UK are 54.8, 1.56 and 0.039wt%, of similar magnitude to the few published comparable sites worldwide. The uppermost peat (0-0.2m) is enriched in P and N (51.0, 1.86, and 0.070wt%) relative to the deeper peat (0.5-1.25m, 56.3, 1.39, and 0.027wt%). Long-term average (whole core) accumulation rates of C, N and P are 25.3±2.2gCm-2year-1 (mean±SE), 0.70±0.09gNm-2year-1 and 0.018±0.004gPm-2year-1, again similar to values reported elsewhere in the world. The two most significant findings are: 1) that a regression model of N concentration on P concentration and mean annual precipitation, based on global meta data for surface peat samples, can explain 54% of variance in N concentration in these UK peat profiles; and 2) budget calculations for the UK peat cores yield an estimate for long-term average N-fixation of 0.8gm-2year-1. Our UK results, and comparison with others sites, corroborate published estimates of N storage in northern boreal peatlands through the Holocene as ranging between 8 and 15Pg N. However, the observed correlation of N% with both mean annual precipitation and P concentration allows a potential bias in global estimates that do not take this into account. The peat sampling data set has been deposited at the NERC Data Centre (Toberman et al., 2016).

Aged riverine particulate organic carbon in four UK catchments.

The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO14C in rivers draining catchments with low erosion rates.

Assessing recovery from acidification of European surface waters in the year 2010: evaluation of projections made with the MAGIC model in 1995.

In 1999 we used the MAGIC (Model of Acidification of Groundwater In Catchments) model to project acidification of acid-sensitive European surface waters in the year 2010, given implementation of the Gothenburg Protocol to the Convention on Long-Range Transboundary Air Pollution (LRTAP). A total of 202 sites in 10 regions in Europe were studied. These forecasts can now be compared with measurements for the year 2010, to give a "ground truth" evaluation of the model. The prerequisite for this test is that the actual sulfur and nitrogen deposition decreased from 1995 to 2010 by the same amount as that used to drive the model forecasts; this was largely the case for sulfur, but less so for nitrogen, and the simulated surface water [NO3(-)] reflected this difference. For most of the sites, predicted surface water recovery from acidification for the year 2010 is very close to the actual recovery observed from measured data, as recovery is predominantly driven by reductions in sulfur deposition. Overall these results show that MAGIC successfully predicts future water chemistry given known changes in acid deposition.

Drought alters carbon fluxes in alpine snowbed ecosystems through contrasting impacts on graminoids and forbs.

• Climate change is predicted to increase the frequency of drought events in alpine ecosystems with the potential to affect carbon turnover. • We removed intact turfs from a Nardus stricta alpine snowbed community and subjected half of them to two drought events of 8 d duration under controlled conditions. Leachate dissolved organic carbon (DOC) was measured throughout the 6 wk study period, and a (13)CO(2) pulse enabled quantification of fluxes of recent assimilate into shoots, roots and leachate and ecosystem CO(2) exchange. • The amount of DOC in leachate from droughted cores was 62% less than in controls. Drought reduced graminoid biomass, increased forb biomass, had no effect on bryophytes, and led to an overall decrease in total above-ground biomass compared with controls. Net CO(2) exchange, gross photosynthesis and the amount of (13)CO(2) fixed were all significantly less in droughted turfs. These turfs also retained proportionally more (13)C in shoots, allocated less (13)C to roots, and the amount of dissolved organic (13)C recovered in leachate was 57% less than in controls. • Our data show that drought events can have significant impacts on ecosystem carbon fluxes, and that the principal mechanism behind this is probably changes in the relative abundance of forbs and grasses.

Regional specificity of magnetic resonance imaging and histopathology following cerebral ischemia in preterm fetal sheep.

Early and accurate evaluation of the nature and extent of cerebral injury in the preterm infant brain is important for prognostication and decision making in the neonatal intensive care unit. The capability of magnetic resonance imaging (MRI) to define acute ischemic changes in white and gray matter in comparison to contemporaneous histopathology has not been adequately ascertained. The aim of this study is to assess whether postmortem MRI predicts the nature and extent of brain injury in a preterm fetal sheep model of cerebral hypoperfusion. MRI examinations were performed on fetal sheep brains (d99-100 gestation), perfusion fixed 72 hours after an ischemic insult (n = 7) with left-hemispheric placement of a microdialysis probe and compared with sham-occlusion (n = 3) and unoperated-control fetuses (n = 4). Cerebral ischemia was associated with MRI changes including global cerebral injury and diffuse white matter signal abnormality, which corresponded closely with histological damage. However, histological changes in deep structures, including the corona radiata, thalamus, and globus pallidus were not reliably detected on MRI. These findings confirm that in preterm fetal sheep, MRI can accurately assess cortical gray matter and subcortical and periventricular white matter abnormalities 3 days after hypoxic-ischemic injury but appears to have limited sensitivity to detect injury to deep structures.

Gestational age-dependent up-regulation of prostaglandin D synthase (PGDS) and production of PGDS-derived antiinflammatory prostaglandins in human placenta.

CONTEXT: The importance of prostaglandin (PG) signaling pathways to the maintenance of pregnancy and initiation of labor is well recognized. However, the complexity of these pathways and the mechanism(s) of their coordinated regulation in physiological and pathological conditions are only now being appreciated. OBJECTIVES: In this report we provide new evidence of a complete pathway for the biosynthesis and actions of PGD(2) and its metabolites within human gestational tissues. MATERIALS AND METHODS: Using immunohistochemistry and Northern and Western blotting, we demonstrate the dynamic regulation of H-type PGD synthase (PGDS) in placenta during gestation; in contrast, L-type PGDS and its PG products were detected in amniotic fluid, with increased amounts associated with labor. RESULTS: Placental tissues were shown to express both forms of the PGD(2) receptor identified to date, D prostanoid(1) (DP(1)) and DP(2)/chemotactic receptor on type 2 helper T cells, with a distribution consistent with the villous placenta being a major target, as well as source, of PGD(2). In vitro, placental PGD(2) production was shown to be stimulated upon inflammatory activation, whereas PGD(2) and its J series metabolites exerted potent inhibitory effects on placental cytokine production. CONCLUSIONS: These findings suggest that PGDS-derived prostanoids play important physiological roles in the placenta, such as immunoregulation and feto-placental communication, while potentially having a regulatory role in the processes of parturition.

Nanomolar and micromolar effects of 15-deoxy-delta 12,14-prostaglandin J2 on amnion-derived WISH epithelial cells: differential roles of peroxisome proliferator-activated receptors gamma and delta and nuclear factor kappa B.

15-Deoxy delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), an activator of peroxisome proliferator-activated receptor (PPAR)-gamma and -delta, is a prostanoid metabolite with anti-inflammatory actions. In intrauterine tissues, proinflammatory cytokines and prostaglandins have been identified as playing key roles in the maintenance of pregnancy and the onset of labor. We investigated and compared the early (<3 h) effects of 15d-PGJ(2) with rosiglitazone (PPAR-gamma ligand) and 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-thiazol-5-yl)-methylsulfanyl)phenoxy-acetic acid (GW501516) (PPAR-delta ligand) on interleukin (IL)-1beta-induced prostaglandin and cytokine production by amnion-derived WISH cells. We show that 15d-PGJ(2) exerts differential effects depending on concentration. At low concentrations (<0.1 microM), 15d-PGJ(2) inhibited IL-1beta-stimulated prostaglandin E(2) (PGE(2)) but not cytokine (IL-6/IL-8) production or cyclooxygenase-2 (COX-2) expression. This effect was attenuated by a PPAR-gamma inhibitor [2-chloro-5-nitro-N-phenyl-benzamide (GW9662)], by transfection with a dominant-negative PPAR construct, and was reproduced by the PPAR-gamma ligand rosiglitazone. At higher concentrations (1-10 microM), 15d-PGJ(2) inhibited IL-1beta-stimulated PGE(2) and cytokine production and COX-2 expression, and this effect was not blocked by GW9662. Rosiglitazone at high concentrations (1-10 microM) stimulated PGE(2) production in the absence or presence of the dominant-negative PPAR. The PPAR-delta ligand GW501516 also inhibited IL-1beta-stimulated PGE(2) production but only at high concentrations (1 microM). IL-1beta-induced nuclear factor-kappaB (NF-kappaB) DNA binding activity was significantly inhibited by 15d-PGJ(2) (10 microM) and GW501516 (1 microM) but increased with 10 microM rosiglitazone. We conclude that 1) at low concentrations, 15d-PGJ(2) acts through a PPAR-gamma signaling pathway; b) at higher concentrations, its actions are mediated most likely through other pathways such as activation of PPAR-delta and/or inhibition of NF-kappaB; and 3) rosiglitazone exerts PPAR-independent effects at high concentrations (>1 microM).

Identification of 9alpha,11beta-prostaglandin F2 in human amniotic fluid and characterization of its production by human gestational tissues.

CONTEXT: 9alpha,11beta-Prostaglandin F(2) (9alpha,11beta-PGF(2)) can contract uterine smooth muscle with a potency equal to PGF(2alpha). Its presence in the human uterus and production by human gestational tissues is unknown. OBJECTIVE: These studies were performed to determine whether the PGD(2)-derived 9alpha,11beta-PGF(2) is both present in human amniotic fluid and synthesized by human gestational tissues and if so, whether labor-related substances could regulate its production. RESULTS: Detectable concentrations of 9alpha,11beta-PGF(2) were found in amniotic fluid samples and appeared to increase in late gestation. All gestational tissues studied synthesized 9alpha,11beta-PGF(2), with the placenta having the highest basal production rate, followed by the amnion and then the choriodecidua. IL-1beta and TNFalpha caused concentration-dependent increases in 9alpha,11beta-PGF(2) production in human amnion and choriodecidual explants. Moreover, treatment of choriodecidual and placental explants with lipopolysaccharide resulted in a significant increase in 9alpha,11beta-PGF(2) production rates, reaching a maximum of 13-fold in the choriodecidua. Studies examining the effects of the addition of exogenous PGD(2) strongly indicated that the choriodecidua has significant ability to convert PGD(2) to 9alpha,11beta-PGF(2), whereas the amnion has little. CONCLUSIONS: These results demonstrate for the first time that 9alpha,11beta-PGF(2) is present in human amniotic fluid and that it is produced by human gestational tissues and up-regulated by bacterial cell wall components and proinflammatory cytokines. We suggest that this prostaglandin may play a part in the mechanisms of human labor at term and preterm.

Characterization of the endocannabinoid system in early human pregnancy.

In recent years, it has been demonstrated that high circulating levels of the endogenous cannabinoid anandamide, resulting from low expression of its metabolizing enzyme fatty acid amide hydrolase (FAAH), may contribute to spontaneous miscarriage and poor outcome in women undergoing in vitro fertilization. The site of action of this compound, however, has not been determined. In this study, we examined the distribution of the cannabinoid receptors, CB1 and CB2, and the endocannabinoid-metabolizing enzyme FAAH in first trimester human placenta. Here, we show that FAAH is expressed throughout the human first trimester placenta, in extravillous trophoblast columns, villous cytotrophoblasts, syncytiotrophoblasts, and macrophages. Furthermore, FAAH mRNA levels appear to be regulated during gestation, with levels peaking at 11 wk before declining again. The immune system-associated cannabinoid CB2 receptors were localized only to placental macrophages. Interestingly, the cannabinoid receptor CB1 was not identified in first trimester placenta despite having previously been shown to be present in placental tissues at term. These findings suggest that the placenta may form a barrier preventing maternal-fetal transfer of anandamide and/or modulate local levels of anandamide by regulation of FAAH expression with gestation.

Differential effects of serum constituents on apoptosis induced by the cyclopentenone prostaglandin 15-deoxy-delta12,14-prostaglandin J2 in WISH epithelial cells.

Cyclopentenone prostaglandins, delta12-PGJ2 and 15d-PGJ2, have potent anti-tumour and anti-inflammatory activities, and have been shown to induce apoptosis in amnion-derived WISH cells. In this study, we have investigated the protective effects of serum and its constituents (growth factors and albumin) on delta12-PGJ2 and 15d-PGJ2-induced apoptosis in WISH cells. Serum (0.5% w/v) was protective against both delta12-PGJ2 and 15d-PGJ2-induced apoptosis. This was not due to the presence of serum-derived growth factors (EGF, IGF-1 and IGF-2), since they had no significant effect on 15d-PGJ2-induced cell death. In contrast, IGF-1 partially inhibited etoposide-induced apoptosis, confirming the presence of a functional IGF-1 receptor signalling system. Albumin was identified as the key survival factor in serum, since albumin and delipidated albumin exhibited the same level of protection from 15d-PGJ2-induced apoptosis as serum itself. The potential for serum albumin to regulate the bioactivity of cyclopentenone PGs may be of considerable importance in pathological conditions where roles for cyclopentenone PGs have been identified.

Prostaglandin synthases: recent developments and a novel hypothesis.

Cells are continuously exposed to cues, which signal cell survival or death. Fine-tuning of these conflicting signals is essential for tissue development and homeostasis, and defective pathways are linked to many disease processes, especially cancer. It is well established that prostaglandins (PGs), as signalling molecules, are important regulators of cell proliferation, differentiation and apoptosis. PG production has been a focus of many researchers interested in the mechanisms of parturition. Previously, investigators have focussed on the committed step of PG biosynthesis, the conversion by prostaglandin H synthase (PGHS; also termed cyclo-oxygenase, COX) of arachidonic acid (AA) (substrate) to PGH2, the common precursor for biosynthesis of the various prostanoids. However, recently the genes encoding the terminal synthase enzymes involved in converting PGH2 to each of the bioactive PGs, including the major uterotonic PGs, PGE2 (PGE synthase) and PGF2alpha (PGF synthase), have been cloned and characterized. This review highlights how the regulation of the expression and balance of key enzymes can produce, from a single precursor, prostanoids with varied and often opposing effects.