Validating the chronic Pb algae bioavailability model at high pH : single-species evaluation : final report, 12 June 2017

We investigated toxicity of Pb to Pseudokirchneriella subcapitata using the standard 72h-growth inhibition assays at 2 pH levels (pH 7.2 & pH 8.4) and 2 P (P 10 ug/L & P 100 ug/L) levels, i.e. at 4 treatments in total. This was done to test whether an existing algae Pb bioavailability model developed for pH≤8.0, can be used at higher pH>8.0. The algae Pb bioavailability model calibrated on Pb toxicity at pH 7.2 (P 100 µg/L) predicted filtered Pb toxicity(EC50 and EC20) at pH 8.4 (P 100 µg/L) with reasonable accuracy, i.e. within 2-fold error. Although the slope of the linear relationship between pH and log10(EC50 as Pb2+ acitivity) for the pH range between 7.2 and 8.4 (present study) was slightly lower than that of the pH range between 6 and 8 (existing model), our study suggests that the chronic algae Pb bioavailability model can be extrapolated to predict Pb toxicity up to pH 8.4

Ecotoxicological and biochemical mixture effects of an herbicide and a metal at the marine primary producer diatom Thalassiosira weissflogii and the primary consumer copepod Acartia tonsa

Mixture effects of chemicals and their potential synergistic interactions are of great concern to the public and regulatory authorities worldwide. Intensive agricultural activities are leading to discharges of chemical mixtures to nearby estuarine and marine waters with possible adverse effects on the aquatic communities and for the trophic food web interlinking these communities. Further information about the impacts of these stressors on aquatic organisms is needed. This study addresses ecotoxicological and biochemical effects of single and mixtures of the metal copper and the herbicide Primextra® Gold TZ on the marine diatom Thalassiosira weissflogii and on the estuarine calanoid copepod Acartia tonsa by determining growth rate and survival, respectively, and changes on fatty acid(FA) profiles in both species. Mixture effects on diatom species revealed that copper and Primextra® acted most likely additively with respect to the concentration addition (CA) and independent action (IA) models with model deviation ratios (MDR), 0.752 and 1.063, respectively. For the copepod species, copper and Primextra® were most likely non-interactive with respect to the CA model (MDR = 1.521) but acted most likely synergistically with respect to the IA model (MDR = 2.026). A significant decline in the absolute FA concentration was observed for copepod species after mixture exposure including a considerable decrease of essential FAs that cannot be synthesized de novo by these grazers. We concluded that the mixture effects are more hazardous for primary consumer than for primary producer species in terms of both abundance and biomass quality, suggesting a potential for harmful effects for higher trophic levels and thus a decrease in energy flow through the ecosystem

Three-dimensional reconstruction of the tissue-specific multielemental distribution within Ceriodaphnia dubia via multimodal registration using laser ablation ICP-mass spectrometry and X-ray spectroscopic techniques

In this work, the three-dimensional elemental, distribution profile within the freshwater crustacean Ceriodaphnia dubia was constructed at a spatial resolution down to S mu m via a data, fusion approach employing state-of-the-art laser ablation inductively coupled plasma-time-of-flight mass spectrometry (LAICP-TOFMS) and laboratory-based absorption microcomputed tomography (mu-CT). C. dubia was exposed to elevated Cu, Ni, and Zn concentrations, chemically fixed, dehydrated, stained, and embedded, prior to mu-CT analysis. Subsequently, the sample was cut into 5 pm thin sections that were subjected to LA-ICPTOFMS imaging. Multimodal image registration was performed to spatially align the 2D LA-ICP-TOFMS images relative to the Corresponding slices of the 3D mu-CT reconstruction. Mass channels corresponding to the isotopes of a single element were merged to improve the signal-to-noise ratios within the elemental images. In order to aid the visual interpretation of the data, LA-ICP-TOEMS data wete projected onto the mu-CT voxels representing tissue. Additionally, the image resolution and elemental sensitivity were compared to those obtained with synchrotron radiation based 3D confocal mu-X-ray fluorescence imaging upon a chemically fixed and air-dried C. dubia specimen

M & L Jaargang 27/4

Charlotte Nys en Sylvie Bruyninckx Het atomium, 50 jaar oud en opnieuw stralend. [The Atomium, 50 years old and radiant as never before.]Het Paviljoen van de Belgische siderurgie en staalindustrie zal bij weinig mensen een belletje doen rinkelen, het Atomium daarentegen des te meer. Oorspronkelijk gebouwd als een tijdelijke Spielerei die zes maanden boven de andere Expo-monumenten zou uittorenen, bleef het Atomium op het Brusselse Heizelplateau min of meer toevallig overeind. Het efemere bouwwerk kon dankzij restauratie en aanpassingswerken omgevormd worden tot een permanent Brussels symboolmonument. Charlotte Nys en Sylvie Bruyninckx geven gedetailleerd relaas.Dieter Nuytten De Pijl op Expo 58 en de hoge vlucht van betonnen schalen. [The arrow at the Expo 58 and the heydays of concrete scales.]De Avenue de la construction op Expo 58 werd beheerst door de Pijl, de populaire benaming voor het Paviljoen van de civiele techniek of burgerlijke bouwkunde. Bij wijze van eerbetoon aan het technisch vernuft van de Belgische ingenieurs van toen, beschrijft Dieter Nuytten vol bewondering de vernuftige bouwtechnieken van dit op het eerste gezicht onevenwichtige bouwsel. Niet de tand des tijds, maar de laag bij de grondse noodzaak voor een nieuw parkeerterrein op de Heizel betekende in de jaren 1970 de doodsteek voor dit stoutmoedige ontwerp.Somchart Chungsiriarak Een wachthuisje voor de koning van Siam. Het Thaise paviljoen voor Expo 58. [Prathinang Arpornphimok-prasat and its reproduction of the Thai Pavilion at Brussels 1958.]Als een buitenmaats geprefabriceerd constructiepakket arriveerde het teakhouten paviljoentje van Thailand op Expo 58, als eenzame vertegenwoordiger van traditionele bouwwijzen tussen al het omringende modernistisch geweld. Omdat iedereen maar voetstoots aannam dat het om een tempeltje ging, vond de Bangkokse restauratiearchitect Somchart Chungsiriarak het hoog tijd om de mythe te ontkrachten en het precieus gebouwtje te ontmaskeren als een reconstructie van het sierlijk verguld wachthuisje voor de koning van Siam.Catheline Metdepenninghen en Dominique Vieren De Normandie, met vlag en wimpel gerestaureerd. [The Normandie, restored with flying colours.]De snelle Franse pakketboot Normandie stond model voor dit interbellum boothotel in de Westvlaamse duinen. De scheepsromp met drie zwart en rood geschilderde schoorstenen, patrijspoorten, masten met wimpels en zelfs reddingsboten zorgden voor een bijna perfecte illusie. Later zouden jarenlange leegstand en de afgelegen ligging echter ongenode gasten aantrekken, tot de bescherming als monument in 1994 de eerste aanzet tot de heropleving geeft. Catheline Metdepenninghen en Dominique Vieren beschrijven beeldrijk hoe dit indrukwekkende gestrande gevaarte dankzij weldoordachte restauratie en een aangepaste herbestemming tot restaurant terug vlot getrokken werd.Summar

An Individual-Oriented Model on the Emergence of Support in Fights, Its Reciprocation and Exchange

Complex social behaviour of primates has usually been attributed to the operation of complex cognition. Recently, models have shown that constraints imposed by the socio-spatial structuring of individuals in a group may result in an unexpectedly high number of patterns of complex social behaviour, resembling the dominance styles of egalitarian and despotic species of macaques and the differences between them. This includes affiliative patterns, such as reciprocation of grooming, grooming up the hierarchy, and reconciliation. In the present study, we show that the distribution of support in fights, which is the social behaviour that is potentially most sophisticated in terms of cognitive processes, may emerge in the same way. The model represents the spatial grouping of individuals and their social behaviour, such as their avoidance of risks during attacks, the self-reinforcing effects of winning and losing their fights, their tendency to join in fights of others that are close by (social facilitation), their tendency to groom when they are anxious, the reduction of their anxiety by grooming, and the increase of anxiety when involved in aggression. Further, we represent the difference in intensity of aggression apparent in egalitarian and despotic macaques. The model reproduces many aspects of support in fights, such as its different types, namely, conservative, bridging and revolutionary, patterns of choice of coalition partners attributed to triadic awareness, those of reciprocation of support and ‘spiteful acts’ and of exchange between support and grooming. This work is important because it suggests that behaviour that seems to result from sophisticated cognition may be a side-effect of spatial structure and dominance interactions and it shows that partial correlations fail to completely omit these effects of spatial structure. Further, the model is falsifiable, since it results in many patterns that can easily be tested in real primates by means of existing data

Effect of cyclo-oxygenase inhibition on embryonic microglia and the sexual differentiation of the brain and behavior of Japanese quail (Coturnix japonica)

peer reviewedEnduring sex differences in the brain are established during a developmental process known as brain sexual differentiation and are mainly driven by estrogens during a critical period. In rodents, the masculinization of the preoptic area by estrogens derived from the central aromatization of testosterone depends in part on the interaction between microglia and prostaglandin E2 (PGE2), a pro-inflammatory hormone of the prostanoid subclass. In contrast, in birds, estrogens produced by females induce a demasculinization, but whether an interaction with the neuro-immune system is involved in this process is unknown. This study addressed this question by testing the effects of blockade of cyclo-oxygenases (COX), the rate-limiting enzymes for prostanoid synthesis, on embryonic microglia and the sexual differentiation of brain and behavior using the Japanese quail as an animal model. The results show that COX inhibition does not affect the behavior of females, but impairs male sexual behavior and suppresses the sex difference in microglial profiles at embryonic day 12 (E12) in the medial preoptic nucleus by increasing the number of microglia in males only. However, neither prostanoid concentrations nor PGE2 receptors differed between sexes in the hypothalamus and preoptic area (HPOA) during development. Overall, these results uncovered a potential role of prostanoids in the demasculinization of Japanese quail. Moreover, the parallel effect of COX inhibition on behavior and microglia suggests an interaction between prostanoids and microglia in brain demasculinization, thus fueling the hypothesis of a conserved role of the neuroimmune system in the organization of the brain by estrogens