Haplosufficient genomic androgen receptor signaling is adequate to protect female mice from induction of polycystic ovary syndrome features by prenatal hyperandrogenization

Polycystic ovary syndrome (PCOS) is associated with reproductive, endocrine, and metabolic abnormalities. Because hyperandrogenism is the most consistent PCOS feature, we used wild-type (WT) and androgen receptor (AR) knockout (ARKO) mice, together with a mouse model of PCOS, to investigate the contribution of genomic AR-mediated actions in the development of PCOS traits. PCOS features were induced by prenatal exposure to dihydrotestosterone (250 μg) or oil vehicle (control) on days 16-18 of gestation in WT, heterozygote, and homozygote ARKO mice. DHT treatment of WT mice induced ovarian cysts (100% vs 0%), disrupted estrous cycles (42% vs 100% cycling), and led to fewer corpora lutea (5.0±0.4 vs 9.8±1.8). However, diestrus serum LH and FSH, and estradiol-induced-negative feedback as well as hypothalamic expression of kisspeptin, neurokinin B, and dynorphin, were unaffected by DHT treatment in WT mice. DHT-treated WT mice exhibited a more than 48% increase in adipocyte area but without changes in body fat. In contrast, heterozygous and homozygous ARKO mice exposed to DHT maintained comparable ovarian (histo)morphology, estrous cycling, and corpora lutea numbers, without any increase in adipocyte size. These findings provide strong evidence that genomic AR signaling is an important mediator in the development of these PCOS traits with a dose dependency that allows even AR haplosufficiency to prevent induction by prenatal androgenization of PCOS features in adult life.

Ciprofloxacin as a potential radio-sensitizer to tumor cells and a radio-protectant for normal cells: differential effects on γ-H2AX formation, p53 phosphorylation, Bcl-2 production, and cell death

Ionizing radiation increases cell mortality in a dose-dependent manner. Increases in DNA double strand breaks, γ-H2AX, p53 phophorylation, and protein levels of p53 and Bax also occur. We investigated the ability of ciprofloxacin (CIP), a widely prescribed antibiotic, to inhibit DNA damage induced by ionizing radiation. Human tumor TK6, NH32 (p53 (-/-) of TK6) cells, and human normal peripheral blood mononuclear cells (PBMCs) were exposed to 2-8 Gy (60)Co-γ-photon radiation. γ-H2AX (an indicator of DNA strand breaks), phosphorylated p53 (responsible for cell-cycle arrest), Bcl-2 (an apoptotic protein, and cell death were measured. Ionizing irradiation increased γ-H2AX amounts in TK6 cells (p53(+/+)) within 1 h in a radiation dose-dependent manner. CIP pretreatment and posttreatment effectively inhibited the increase in γ-H2AX. CIP pretreatment reduced Bcl-2 production but promoted p53 phosphorylation, caspase-3 activation and cell death. In NH32 cells, CIP failed to significantly inhibit the radiation-induced γ-H2AX increase, suggesting that CIP inhibition involves in p53-dependent mechanisms. In normal healthy human PBMCs, CIP failed to block the radiation-induced γ-H2AX increase but effectively increased Bcl-2 production, but blocked the phospho-p53 increase and subsequent cell death. CIP increased Gadd45α, and enhanced p21 protein 24 h postirradiation. Results suggest that CIP exerts its effect in TK6 cells by promoting p53 phosphorylation and inhibiting Bcl-2 production and in PBMCs by inhibiting p53 phosphorylation and increasing Bcl-2 production. Our data are the first to support the view that CIP may be effective to protect normal tissue cells from radiation injury, while enhancing cancer cell death in radiation therapy.

The role of kisspeptin and gonadotropin inhibitory hormone in the seasonal regulation of reproduction in sheep

Sheep are seasonal breeders, experiencing an annual period of reproductive quiescence in response to increased photoperiod during the late-winter into spring and renaissance during the late summer. The nonbreeding (anestrous) season is characterized by a reduction in the pulsatile secretion of GnRH from the brain, in part because of an increase in negative feedback activity of estrogen. Neuronal populations in the hypothalamus that produce kisspeptin and gonadotropin-inhibitory hormone (GnIH) appear to be important for the seasonal shift in reproductive activity, and the former are also mandatory for puberty onset. Kisspeptin cells in the arcuate nucleus (ARC) and preoptic area appear to regulate GnRH neurons and transmit sex-steroid feedback signals to these neurons. Moreover, kisspeptin expression in the ARC is markedly up-regulated at the onset of the breeding season, as too are the number of kisspeptin fibers in close apposition to GnRH neurons. The lower levels of kisspeptin seen during the nonbreeding season can be "corrected" by infusion of kisspeptin, which causes ovulation in seasonally acyclic females. The role of GnIH is less clear, but mounting evidence supports a role for this neuropeptide in the inhibitory regulation of both GnRH secretion and gonadotropin release from the pituitary gland. Contrary to kisspeptin, GnIH expression is markedly reduced at the onset of the breeding season. In addition, the number of GnIH fibers in close apposition to GnRH neurons also decreases during this time. Importantly, exogenous GnIH treatment can block both the pulsatile release of LH and the preovulatory LH surge during the breeding season. In summary, it is most likely the integrated function of both these neuropeptide systems that modulate the annual shift in photoperiod to a physiological change in fertility.

Low dose ionizing radiation produces too few reactive oxygen species to directly affect antioxidant concentrations in cells

It has been hypothesized that radiation-induced oxidative stress is the mechanism for a wide range of negative impacts on biota living in radioactively contaminated areas around Chernobyl. The present study tests this hypothesis mechanistically, for the first time, by modelling the impacts of radiolysis products within the cell resulting from radiations (low linear energy transfer β and γ), and dose rates appropriate to current contamination types and densities in the Chernobyl exclusion zone and at Fukushima. At 417 µGy h(-1) (illustrative of the most contaminated areas at Chernobyl), generation of radiolysis products did not significantly impact cellular concentrations of reactive oxygen species, or cellular redox potential. This study does not support the hypothesis that direct oxidizing stress is a mechanism for damage to organisms exposed to chronic radiation at dose rates typical of contaminated environments.

Kisspeptin cells in the ovine arcuate nucleus express prolactin receptor but not melatonin receptor

Melatonin is secreted at night by the pineal gland and governs the reproductive system in seasonal breeders, such as sheep. The mechanism by which melatonin regulates reproduction is not known. The circannual rhythmicity of other factors, including prolactin, is also regulated by photoperiod via changes in melatonin secretion. In sheep, plasma prolactin levels are higher in the nonbreeding season than the breeding season. Kisspeptin, synthesised by neurones in the ovine arcuate nucleus (ARC) and preoptic area, is a key regulator of reproduction through stimulation of gonadotrophin-releasing hormone secretion and its expression in the ARC is reduced during the nonbreeding season. We hypothesised that kisspeptin expression is directly, or indirectly, regulated by melatonin and/or prolactin. We first examined the expression of melatonin receptor (MTNR1A) in kisspeptin (Kiss1 mRNA) neurones in the ARC of ovariectomised (OVX) sheep using double-label in situ hybridisation. MTNR1A mRNA was not expressed by kisspeptin neurones, whereas strong expression was detected in the pars tuberalis. We then examined the expression of the long-form prolactin receptor (PRLR-L) in ARC kisspeptin neurones. In OVX ewes, approximately 60% of kisspeptin neurones expressed PRLR-L mRNA at similar levels in the breeding and nonbreeding seasons. We then aimed to determine whether prolactin treatment during the breeding season regulates kisspeptin expression in the ARC. Continuous central infusion of prolactin (20 μg/h for 7 days) in oestradiol-treated OVX sheep did not alter Kiss1 mRNA expression or luteinising hormone secretion, although it induced substantial phosphorylated signal transducer and activator of transcription 5-immunoreactive nuclei staining in the mediobasal hypothalamus. We conclude that the seasonal change in kisspeptin neurones cannot be regulated directly by melatonin, although it may be a result of changes in prolactin levels. Despite this, kisspeptin expression was unchanged after exogenous prolactin treatment in breeding season ewes.

Changes in water quality of the River Frome (UK) from 1965 to 2009: is phosphorus mitigation finally working?

The water quality of the River Frome, Dorset, southern England, was monitored at weekly intervals from 1965 until 2009. Determinands included phosphorus, nitrogen, silicon, potassium, calcium, sodium, magnesium, pH, alkalinity and temperature. Nitrate-N concentrations increased from an annual average of 2.4 mg l⁻¹ in the mid to late 1960s to 6.0 mg l⁻¹ in 2008-2009, but the rate of increase was beginning to slow. Annual soluble reactive phosphorus (SRP) concentrations increased from 101 μg l⁻¹ in the mid 1960s to a maximum of 190 μg l⁻¹ in 1989. In 2002, there was a step reduction in SRP concentration (average=88 μg l⁻¹ in 2002-2005), with further improvement in 2007-2009 (average=49 μg l⁻¹), due to the introduction of phosphorus stripping at sewage treatment works. Phosphorus and nitrate concentrations showed clear annual cycles, related to the timing of inputs from the catchment, and within-stream bioaccumulation and release. Annual depressions in silicon concentration each spring (due to diatom proliferation) reached a maximum between 1980 and 1991, (the period of maximum SRP concentration) indicating that algal biomass had increased within the river. The timing of these silicon depressions was closely related to temperature. Excess carbon dioxide partial pressures (EpCO₂) of 60 times atmospheric CO₂ were also observed through the winter periods from 1980 to 1992, when phosphorus concentration was greatest, indicating very high respiration rates due to microbial decomposition of this enhanced biomass. Declining phosphorus concentrations since 2002 reduced productivity and algal biomass in the summer, and EpCO₂ through the winter, indicating that sewage treatment improvements had improved riverine ecology. Algal blooms were limited by phosphorus, rather than silicon concentration. The value of long-term water quality data sets is discussed. The data from this monitoring programme are made freely available to the wider science community through the CEH data portal (http://gateway.ceh.ac.uk/).

Abundance and diversity of aquatic macroinvertebrate communities in lakes exposed to Chernobyl-derived ionising radiation

Littoral (lake shore) macroinvertebrate communities were studied in eight natural lakes affected by fallout from the Chernobyl accident. The lakes spanned a range in (137)Cs contamination from 100 to 15500 kBq m(-2) and estimated external dose rates ranged from 0.13 to 30.7 μGy h(-1). General linear models were used to assess whether abundance of individuals, taxon richness, Berger-Parker dominance and Shannon-Wiener diversity varied across the lakes. Step-wise multiple regressions were used to relate variation in total abundance, taxon richness, Berger-Parker dominance, Shannon-Wiener diversity, taxon richness within major groups of macroinvertebrates and abundance of the more common individual taxa to the measured environmental characteristics (conductivity, pH, total hardness and phosphate; lake area, lake maximum depth and total external dose) of the lakes. No evidence was found in this study that the ecological status of lake communities has been influenced by radioactive contamination from the Chernobyl accident. Indeed, the most contaminated lake, Glubokoye, contained the highest richness of aquatic invertebrates. Taxon richness in the eight study lakes varied from 22 (Svyatskoe #7) to 42 (Glubokoye) which spans a range typical for uncontaminated lakes in the region. Since (90)Sr is readily-absorbed by Mollusca, estimated dose rates to this group exceeded those for other invertebrate groups in two lakes (Perstok and Glubokoye). However this study found no association between mollusc diversity or abundance of individual snail species and variation between lakes in the external radiation dose. Indeed Glubokoye, the lake most contaminated by (90)Sr, had the highest richness of freshwater snails per sample (an average of 8.9 taxa per sample).

17-DMAG diminishes hemorrhage-induced small intestine injury by elevating Bcl-2 protein and inhibiting iNOS pathway, TNF-α increase, and caspase-3 activation

BACKGROUND

Hemorrhage increases inducible nitric oxide synthase (iNOS) and depletes ATP levels in various tissues. Previous studies have shown that geldanamycin, an inducer of heat shock protein 70kDa (HSP-70) and inhibitor of iNOS, limits both processes. Reduction in NO production limits lipid peroxidation, apoptosome formation, and caspase-3 activation, thereby increasing cellular survival and reducing the sequelae of hemorrhage. The poor solubility of geldanamycin in aqueous solutions, however, limits its effectiveness as a drug. 17-DMAG is a water-soluble analog of geldanamycin that might have greater therapeutic utility. This study investigated the effectiveness of 17-DMAG at reducing hemorrhagic injury in mouse small intestine.

RESULTS

In mice, the hemorrhage-induced iNOS increase correlated with increases in Kruppel-like factor 6 (KLF6) and NF-kB and a decrease in KLF4. As a result, increases in NO production and lipid peroxidation occurred. Moreover, hemorrhage also resulted in decreased Bcl-2 and increased TNF-α, IL-6, and IL-10 concentrations, p53 protein, caspase-3 activation, and cellular ATP depletion. A shortening and widening of villi in the small intestine was also observed. Treatment with 17-DMAG significantly reduced the hemorrhage-induced increases in iNOS protein, jejunal alteration, and TNF-α and IL-10 concentrations, but 17-DMAG did not affect the hemorrhage-induced increases in p53 and IL-6 concentration. 17-DMAG treatment by itself upregulated HSP-70, Bcl-2, and p53.

CONCLUSION

Since 17-DMAG is water soluble, bioactive, and not toxic, 17-DMAG may prove useful as a prophylactic drug for hemorrhage.

A review and model assessment of (32)P and (33)P uptake to biota in freshwater systems

Bioaccumulation of key short-lived radionuclides such as (131)I and (32,33)P may be over-estimated since concentration ratios (CRs) are often based on values for the corresponding stable isotope which do not account for radioactive decay during uptake via the food chain. This study presents estimates for bioaccumulation of radioactive phosphorus which account for both radioactive decay and varying ambient levels of stable P in the environment. Recommended interim CR values for radioactive forms of P as a function of bioavailable stable phosphorus in the water body are presented. Values of CR are presented for three different trophic levels of the aquatic food chain; foodstuffs from all three trophic levels may potentially be consumed by humans. It is concluded that current recommended values of the CR are likely to be significantly over-estimated for radioactive phosphorus in many freshwater systems, particularly lowland rivers. Further research is recommended to field-validate these models and assess their uncertainty. The relative importance of food-chain uptake and direct uptake from water are also assessed from a review of the literature. It can be concluded that food-chain uptake is the dominant accumulation pathway in fish and hence accumulation factors for radioactive phosphorus in farmed fish are likely to be significantly lower than those for wild fish.

Evidence that RF-amide related peptide-3 is not a mediator of the inhibitory effects of psychosocial stress on gonadotrophin secretion in ovariectomised ewes

It is well known that stress inhibits normal reproductive function, including gonadotrophin secretion; however, the mechanisms and mediators involved are largely unknown. Stress impairs the secretion of luteinising hormone (LH), and it has been suggested that the RF-amide gonadotrophin-inhibitory hormone (GnIH), known as RF-amide related peptide-3 (RFRP-3) in mammalian species, may mediate this inhibitory effect of stress. If this is the case, the GnIH/RFRP system would likely be up-regulated during stress. We tested this hypothesis in ovariectomised ewes using a psychosocial stressor: isolation/restraint. Ewes were randomly allocated to control or stress (n=5 per group). Isolation/restraint stress was imposed for 90 min after control sampling for 4 h, whereas control ewes were sampled continuously for 5.5 h. All ewes were then euthanased and brains were collected. As expected, plasma concentrations of cortisol were increased significantly (P<0.05) by stress and plasma concentrations of LH were significantly (P<0.05) reduced. Immunohistochemistry and in situ hybridisation were conducted for RFRP-3 peptide and RFRP mRNA expression, respectively, in the paraventricular nucleus/dorsal medial hypothalamus region of the hypothalamus. There was no significant effect of stress on RFRP-3 peptide or mRNA levels, with no differences between control or stress ewes. Furthermore, there was no difference in the number of RFRP-3 cells double-labelled for Fos between control and stress ewes and there was no difference in the cellular expression of RFRP mRNA between groups. These results indicate that the GnIH/RFRP system is not activated by psychosocial stress in ewes, suggesting that it is an unlikely mediator of the effects of stress on LH secretion.

Are groundwater nitrate concentrations reaching a turning point in some chalk aquifers?

In past decades, there has been much scientific effort dedicated to the development of models for simulation and prediction of nitrate concentrations in groundwaters, but producing truly predictive models remains a major challenge. A time-series model, based on long-term variations in nitrate fertiliser applications and average rainfall, was calibrated against measured concentrations from five boreholes in the River Frome catchment of Southern England for the period spanning from the mid-1970s to 2003. The model was then used to "blind" predict nitrate concentrations for the period 2003-2008. To our knowledge, this represents the first "blind" test of a model for predicting nitrate concentrations in aquifers. It was found that relatively simple time-series models could explain and predict a significant proportion of the variation in nitrate concentrations in these groundwater abstraction points (R(2)=0.6-0.9 and mean absolute prediction errors 4.2-8.0%). The study highlighted some important limitations and uncertainties in this, and other modelling approaches, in particular regarding long-term nitrate fertiliser application data. In three of the five groundwater abstraction points (Hooke, Empool and Eagle Lodge), once seasonal variations were accounted for, there was a recent change in the generally upward historical trend in nitrate concentrations. This may be an early indication of a response to levelling-off (and declining) fertiliser application rates since the 1980s. There was no clear indication of trend change at the Forston and Winterbourne Abbas sites nor in the trend of nitrate concentration in the River Frome itself from 1965 to 2008.

An international model validation exercise on radionuclide transfer and doses to freshwater biota

Under the International Atomic Energy Agency (IAEA)'s EMRAS (Environmental Modelling for Radiation Safety) programme, activity concentrations of (60)Co, (90)Sr, (137)Cs and (3)H in Perch Lake at Atomic Energy of Canada Limited's Chalk River Laboratories site were predicted, in freshwater primary producers, invertebrates, fishes, herpetofauna and mammals using eleven modelling approaches. Comparison of predicted radionuclide concentrations in the different species types with measured values highlighted a number of areas where additional work and understanding is required to improve the predictions of radionuclide transfer. For some species, the differences could be explained by ecological factors such as trophic level or the influence of stable analogues. Model predictions were relatively poor for mammalian species and herpetofauna compared with measured values, partly due to a lack of relevant data. In addition, concentration ratios are sometimes under-predicted when derived from experiments performed under controlled laboratory conditions representative of conditions in other water bodies.

Predicting the radiation exposure of terrestrial wildlife in the Chernobyl exclusion zone: an international comparison of approaches

There is now general acknowledgement that there is a requirement to demonstrate that species other than humans are protected from anthropogenic releases of radioactivity. A number of approaches have been developed for estimating the exposure of wildlife and some of these are being used to conduct regulatory assessments. There is a requirement to compare the outputs of such approaches against available data sets to ensure that they are robust and fit for purpose. In this paper we describe the application of seven approaches for predicting the whole-body ((90)Sr, (137)Cs, (241)Am and Pu isotope) activity concentrations and absorbed dose rates for a range of terrestrial species within the Chernobyl exclusion zone. Predictions are compared against available measurement data, including estimates of external dose rate recorded by thermoluminescent dosimeters attached to rodent species. Potential reasons for differences between predictions between the various approaches and the available data are explored.