The impact of maternal separation on adult mouse behaviour and on the total neuron number in the mouse hippocampus

The maternal separation paradigm has been applied to C57BL/6J mice as an animal developmental model for understanding structural deficits leading to abnormal behaviour. A maternal separation (MS) model was used on postnatal day (PND) 9, where the pups were removed from their mother for 24 h (MS24). When the pups were 10 weeks old, the level of anxiety and fear was measured with two behavioural tests; an open field test and an elevated plus maze test. The Barnes platform maze was used to test spatial learning, and memory by using acquisition trials followed by reverse trial sessions. The MS24 mice spent more time in the open arms of the elevated plus maze compared to controls, but no other treatment differences were found in the emotional behavioural tests. However, in the reverse trial for the Barnes maze test there was a significant difference in the frequency of visits to the old goal, the number of errors made by the MS24 mice compared to controls and in total distance moved. The mice were subsequently sacrificed and the total number of neurons estimated in the hippocampus using the optical fractionator. We found a significant loss of neurons in the dentate gyrus in MS mice compared to controls. Apparently a single maternal separation can impact the number of neurons in mouse hippocampus either by a decrease of neurogenesis or as an increase in neuron apoptosis. This study is the first to assess the result of maternal separation combining behaviour and stereology

Effects of Alternative Outcome Scenarios and Structured Outcome Evaluation on Case-Based Ethics Instruction

Case-based instruction has been regarded by many as a viable alternative to traditional lecture-based education and training. However, little is known about how case-based training techniques impact training effectiveness. This study examined the effects of two such techniques: (a) presentation of alternative outcome scenarios to a case, and (b) conducting a structured outcome evaluation. Consistent with the hypotheses, results indicate that presentation of alternative outcome scenarios reduced knowledge acquisition, reduced sense-making and ethical decision-making strategy use, and reduced decision ethicality. Conducting a structured outcome evaluation had no impact on these outcomes. Results indicate that those who use case-based instruction should take care to use clear, less complex cases with only a singular outcome if they are seeking these types of outcomes

Sublethal and sex-specific cypermethrin effects in toxicity testing with the midge *Chironomus riparius* Meigen

Goedkoop W, Spann N, Åkerblom N. Sublethal and sex-specific cypermethrin effects in toxicity testing with the midge *Chironomus riparius* Meigen. Ecotoxicology. 2010;19(7):1201-1208.We quantified sublethal and sex-specific cypermethrin effects in experiments (29 days) with the midge Chironomus riparius at different levels of sediment organic matter content (0, 5, and 20%). We found highly significant effects of cypermethrin concentrations and sediment type on emergence, mean development rate, and adult size. For example, emergence/survival rates were 70–100% below 0.8 μg/l and unaffected by organic matter content. At 3.2 μg/l, however, no larvae survived in sediment without organic matter, but survival successively increased to 26 ± 11% in sediment with 20% organic matter. Mean development rates were always higher for males than for females, and significant differences between sexes occurred consistently in controls and in treatments with our lowest concentration of 0.05 μg/l. Sex-specific differences in mean development rate decreased across the cypermethrin gradient, suggesting that male development was affected more than that of females at similar concentrations. We also found an increase in adult size across the concentration gradient in sediments lacking organic matter and suggest an increased feeding activity due to sublethal toxic stress as a probable causal mechanism. We speculate that the observed sex-specific effects on development rates and adult size can have strong repercussions on emergence timing and fecundity, respectively