In recent years, an intense debate about the environmental risks posed by neonicotinoids, a group of widely used, neurotoxic insecticides, has been joined. When these systemic compounds are applied ...to seeds, low concentrations are subsequently found in the nectar and pollen of the crop, which are then collected and consumed by bees. Here we demonstrate that the current focus on exposure to pesticides via the crop overlooks an important factor: throughout spring and summer, mixtures of neonicotinoids are also found in the pollen and nectar of wildflowers growing in arable field margins, at concentrations that are sometimes even higher than those found in the crop. Indeed, the large majority (97%) of neonicotinoids brought back in pollen to honey bee hives in arable landscapes was from wildflowers, not crops. Both previous and ongoing field studies have been based on the premise that exposure to neonicotinoids would occur only during the blooming period of flowering crops and that it may be diluted by bees also foraging on untreated wildflowers. Here, we show that exposure is likely to be higher and more prolonged than currently recognized because of widespread contamination of wild plants growing near treated crops.
Endophytic fungi live asymptomatically within plants. They are usually regarded as nonpathogenic or even mutualistic, but whether plants respond antagonistically to their presence remains unclear, ...particularly in the little‐studied associations between endophytes and nongraminoid herbaceous plants. We investigated the effects of the endophyte Chaetomium cochlioides on leaf chemistry in Cirsium arvense. Plants were sprayed with spores; leaf material from both subsequent new growth and the sprayed leaves was analysed 2 wk later. Infection frequency was 91% and 63% for sprayed and new growth, respectively, indicating that C. cochlioides rapidly infects new foliage. Metabolomic analyses revealed marked changes in leaf chemistry with infection, especially in new growth. Changes in several novel oxylipin metabolites were detected, including arabidopsides reported here for the first time in a plant species other than Arabidopsis thaliana, and a jasmonate‐containing galactolipid. The production of these metabolites in response to endophyte presence, particularly in newly infected foliage, suggests that endophytes elicit similar chemical responses in plants to those usually produced following wounding, herbivory and pathogen invasion. Whether endophytes benefit their hosts may depend on a complex series of chemically mediated interactions between the plant, the endophyte, other microbial colonists and natural enemies.
The widespread occurrence of feminized male fish downstream of some UK Wastewater Treatment Works (WwTWs) has been associated with exposure to estrogenic and potentially antiandrogenic (AA) ...contaminants in the effluents. In this study, profiling of AA contaminants in WwTW effluents and fish was conducted using HPLC in combination with in vitro androgen receptor transcription screens. Analysis of extracts of wastewater effluents revealed complex profiles of AA activity comprising 21–53 HPLC fractions. Structures of bioavailable antiandrogens were identified by exposing rainbow trout to a WwTW effluent and profiling the bile for AA activity using yeast (anti-YAS) and mammalian-based (AR-CALUX) androgen receptor transcription screens. The predominant fractions with AA activity in both androgen receptor screens contained the germicides chlorophene and triclosan, and together these contaminants accounted for 51% of the total anti-YAS activity in the fish bile. Other AA compounds identified in bile included chloroxylenol, dichlorophene, resin acids, napthols, oxybenzone, 4-nonylphenol, and bisphenol A. Pure standards of these compounds were active in the androgen receptor screens at potencies relative to flutamide of between 0.1 and 13.0. Thus, we have identified, for the first time, a diverse range of AA chemicals in WwTWs that are bioavailable to fish and which need to be assessed for their risk to the reproductive health of these organisms and other aquatic biota.
Exposure of fish to wastewater treatment works (WwTWs) effluents can result in reproductive anomalies consistent with exposure to estrogenic compounds. However, UK WwTWs effluents also contain ...compounds with androgen receptor activities which may contribute to reproductive dysfunction in fish. A toxicity identification and evaluation (TIE) approach was used to profile (anti)androgenic compounds in bile of fish exposed to two WwTWs effluents. Extracts of bile from exposed fish and effluent were fractionated by liquid chromatography and tested for (anti)androgenic activity using a yeast androgen receptor transcription screen (YAS). A number of bile fractions contained (anti)androgenic activity unique to the effluent-exposed fish. Some of these fractions contained di(chloromethyl)anthracene or dichlorophene, and these contaminants showed antagonistic activity in the YAS when tested as pure compounds. No androgenic activity was detected in the effluents, but TIE analysis of bile revealed a number of androgenic fractions which contained testosterone metabolites that were unique to effluent-exposed fish. This is the first work reported on the nature of some of the (anti)androgenic compounds that bioaccumulate in fish from WwTWs effluents and indicates that other contaminants, besides estrogenic substances, need to be considered for their potential to contribute to the disruption of reproductive system of fish in UK waters.
The jumping spider Cosmophasis umbratica from Singapore is strongly sexually dimorphic. The males, but not the females, reflect ultraviolet as well as green-orange light. The scales responsible for ...this are composed of a chitin-air-chitin sandwich in which the chitin layers are three-quarters of a wavelength thick and the air gap a quarter wavelength (where λ=600 nm, the peak wavelength of the principal reflection maximum). It is shown that this configuration produces a second reflectance peak at approximately 385 nm, accounting for the observed reflection in the ultraviolet. Other scales have a similar thickness of chitin but lack the air gap and thus produce a dull purple reflection. This novel mechanism provides the spiders with two colour signals, both of which are important in mating displays.
Exposure to environmental estrogens such as 17α-ethinylestradiol (EE2) has been associated with feminization and a decline in fertility of male fish. To investigate the effect of estrogen exposure on ...steroid homeostasis, we exposed roach (Rutilus rutilus) to EE2 (1−29 ng/L) for 18 days and analyzed steroid profiles in bile and plasma using targeted analyses and in liver and gonadal tissues using mass spectrometry metabolite profiling techniques (metabolomics). Exposure to EE2 resulted in a concentration dependent reduction of estrogens and androgens in bile and plasma of both male and female fish. At 10 ngEE2/L, significant reductions in concentrations of hydroxyprogesterone, androstenedione, 11-hydroxyandrostenedione, and 11-ketotestosterone were detected in the testes metabolome, indicating disruption of steroid biosynthesis upstream of androgen metabolism. Estrogen exposure also resulted in increased biosynthesis of cortisol and cortisone in testes and ovaries, respectively, but did not alter glucocorticoid concentrations in the liver or plasma. This first report on the effect of EE2 exposure on the steroid metabolome in fish tissues suggests that both sex steroid and glucocorticoid pathways are one of the primary targets of estrogen exposure in fish gonads and provides further insights into the mode of action of this endocrine disrupting chemical.
5‐Hydroxytryptamine (5‐HT)2C and 5‐HT1B receptors are implicated in the inhibitory modulation of feeding behaviour. However, their respective, and possibly different, roles have not been clearly ...identified because of a lack of selective 5‐HT2C receptor agonists. Here, using the putative, selective 5‐HT2C receptor agonist VER23779, we show that its effects on feeding are fully reversed by pretreatment with a selective 5‐HT2C receptor antagonist, but unaffected by pretreatment with either a 5‐HT1B or a 5‐HT2A receptor antagonist. In mice eating a palatable mash, feeding ends earlier, inactivity is increased but the behavioural satiety sequence is preserved. In a second‐order schedule of reinforcement with an initial, non‐food‐reinforced appetitive phase, VER23779 produces a much greater relative reduction in appetitive responding than the 5‐HT1B receptor agonist CP‐94,253. Increased c‐fos immunoreactivity patterns following VER23779 also differ from those described for CP‐94,253, in particular showing strong activation of the basolateral amygdala. The different behavioural consequences of 5‐HT2C and 5‐HT1B receptor activation may relate to the patterns of c‐fos immunoreactivity. In particular, the basolateral amygdala may have a role in maintaining response in the appetitive phase of the second‐order schedule and also be susceptible to serotonergic modulation through activation of 5‐HT2C receptors.
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