Bioaccumulation and molecular effects of sediment-bound metals in zebrafish embryos

Predicting the bioavailability and effects of metals in sediments is of major concern in context with sediment risk assessment. This study aimed to investigate the bioavailability and molecular effects of metals spiked into riverine sediments to zebrafish (Danio rerio) embryos. Embryos were exposed to a natural and an artificial sediment spiked with cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) individually or as a mixture at concentrations ranging from 150 to 3000 mg/kg dry weight (dw) over 48 h, and uptake of metals was determined. Furthermore, transcript abundances of the metallothioneins MT1 and MT2, the metal-responsive element-binding transcription factor (MTF) and the genes sod1, hsp70 and hsp90α1 were measured as indicators of metal-induced or general cellular stress. D. rerio embryos accumulated metals from sediments at concentrations up to 100 times greater than those spiked to the sediment with the greatest bioaccumulation factor (BAF) for Cu from artificial sediment (275.4 ± 41.9 (SD)). Embryos accumulated greater concentrations of all metals from artificial than from natural sediment, and accumulation was greater when embryos were exposed to individual metals than when they were exposed to the mixture. Exposure of embryos to Zn or the mixture exhibited up to 30-fold greater transcript abundances of MT1, MT2 and hsp70 compared to controls which is related to significant uptake of Zn from the sediment. Further changes in transcript abundances could not be related to a significant uptake of metals from sediments. These studies reveal that metals from spiked sediments are bioavailable to D. rerio embryos directly exposed to sediments and that the induction of specific genes can be used as biomarkers for the exposure of early life stages of zebrafish to metal-contaminated sediments.

Ecotoxicological effect characterisation of widely used organic UV filters

Chemical UV filters are used in sun protection and personal care products in order to protect consumers from skin cancer induced by ultraviolet (UV) radiation. The present study aims to evaluate the effects of three common UV filters butyl-methoxydibenzoylmethane (B-MDM) ethylhexyl-methoxycinnamate (EHMC) and octocrylene (OCR) on aquatic organism, focussing particularly on infaunal and epibentic invertebrates (Chironomus riparius, Lumbriculus variegatus, Melanoides tuberculata and Potamopyrgus antipodarum). Due to their life habits, these organism are especially affected by lipophilic substances. Additionally, two direct sediment contact assays utilising zebra fish (Danio rerio) embryos and bacteria (Arthrobacter globiformis) were conducted. EHMC caused a toxic effect on reproduction in both snails with lowest observed effect concentrations (LOEC) of 0.4 mg/kg (Potamopyrgus antipodarum) and 10 mg/kg (Melanoides tuberculata). At high concentrations sublethal effects could be observed for D. rerio after exposure to EHMC (NOEC 100 mg/kg). B-MDM and OCR showed no effects on any of the tested organism.

Online lectures for students in dermatology: a replacement for traditional teaching or a valuable addition?

INTRODUCTION/OBJECTIVE

Although the Internet, podcasts and multimedia have become a natural part of our life, these instruments still do not find widespread use in medical education. We aimed to increase the percentage of students benefiting from our lectures during their 6-month principal training period in dermatology by making lectures available online.

METHODS

To establish a baseline, we started to count and calculate the average percentage of students attending face to face classes. For the next semester, with a new student generation, we made recordings of about half of the lectures and made them available online. After this testing period, we informed the next new student population at the beginning of the following semester that all lectures would be recorded and made available online. Students' attendance was documented during these periods, and in addition, questionnaires were used to assess students' acceptance and use of the online lectures.

RESULTS

At the end of the project, 66% of the students (n = 256) indicated that they had used the online lectures, and 12% of all students stated that they were usually unable to attend lectures due to conflicting obligations, but could now participate thanks to the e-learning programme. An additional 44.9% of all respondents indicated that they welcomed the e-learning programme as a way to view specific lectures. The average attendance of face-to-face lectures did not decrease.

CONCLUSION

Online lectures in dermatology were highly welcomed by our students and may be a good means to improve the education of students in dermatology.