OECD 236的鱼类胚胎实验(Fish Embryo Test, FET)是否足够敏感，能有效进行排水风险评价吗？

近年来,由于“动物友好”协议的广泛应用,鱼类胚胎实验(Fish Embryo Test, FET)成为了生态毒理学研究的主要方法。OECD 236 FET方法在REACH法规所辖范围内广泛应用,主要针对简单混合物暴露情况(simple mixture exposures),但其还在世界范围内被盲目地用于排放废水综合测试(Whole Effluent Test, WET),这是一种复杂混合物暴露情况。然而,评价FET方法用于WET的有效性的可靠数据几乎没有。本文将OECD 236 FET方法与其他国际通用的标准的和略作改进的生态毒理学研究方案进行了比较,得出了可用于WET的测试方法的总体评价结果。我们使用了未经处理的医院排水,通常认为该排水具有高毒性,且会进入市政污水处理系统。我们选择的毒性测试方法包括OECD 203 (juvenile), USEPA 2000.0 (larva) and OECD 236 (embryo)。值得一提的是,我们还额外测试了3个亚致死指标(不移动性、不孵化率、心包囊肿),这些指标可以提高OECD 236方法的敏感性。我们在所选的8种方法中考察了急性毒性数据,方法的敏感性均有提高且胚胎实验≤仔鱼实验<幼鱼实验(Embryo≤Juvenile 详情请见 https://doi.org/10.1002/etc.4215
     

A protein signal triggers sexual reproduction in Brachionus plicatilis (Rotifera)

The defining feature of the life cycle in monogonont rotifers such as Brachionus plicatilis (Muller) is alternation of asexual and sexual reproduction (mixis). Why sex is maintained in such life cycles is an important unsolved evolutionary question and one especially amenable to experimental analysis. Mixis is induced by a chemical signal produced by the rotifers which accumulates to threshold levels at high population densities. The chemical features of this signal were characterized using size exclusion, enzymatic degradation, protease protection assays, selective binding to anion ion exchange and C3 reversed phase HPLC columns, and the sequence of 17 N-terminal amino acids. These studies were carried out over two years beginning in 2003 using B. plicatilis Russian strain. When rotifer-conditioned medium was treated with proteinase K, its mixis-inducing ability was reduced by 70%. Proteinase K was added to medium auto-conditioned by 1 female ml⁻¹ where typically 17% of daughters became mictic and mixis was reduced to 1%. A cocktail of protease inhibitors added to conditioned medium significantly reduced degradation of the mixis signal by natural proteases. Conditioned medium subjected to ultrafiltration retained mixis-inducing activity in the >10 kDa fraction, but the <10 kDa fraction had no significant activity. The putative mixis signal bound to an anion exchange column, eluting off at 0.72 M NaCl. These fractions were further separated on a C3 reversed phase HPLC column and mixis-inducing activity was associated with a 39 kDa protein. Seventeen amino acids from the N-terminus have strong similarity to a steroidogenesis-inducing protein isolated from human ovarian follicular fluid. The 39 kDa protein is an excellent candidate for the rotifer mixis induction signal.     

Effect of Compatibilizing Agent on the Properties of Highly Crystalline Composites Based on Poly(lactic acid) and Wood Flour and/or Mica

This article contains a concept of the mechanical properties improvement of the highly crystalline poly(lactic acid) (PLA) and filled composites. PLA as a semi-crystalline thermoplastic polymer was plasticized with poly(ethylene glycol) and filled with 30 vol% of organic and/or inorganic filler. The degree of crytallinity was intentionally increased by annealing. The filler/polymer matrix interphase was modified with the addition of 4, 4′-Methylenediphenyl diisocyanate (MDI). The effect of compatibilizing as well as plasticizing agent on the thermal and mechanical properties, the water-absorption behaviour and crystallization characteristics were studied. The results indicated that high content of filler and crystallites have a strong influence on the composite′s mechanical properties despite of the plasticizer content, showing a high Young modulus. The MDI seems to react in preference easy with plasticizing agent and then alternatively with filler due to the low functionality of commercial PLA grade.     

Assessment of in situ biodegradation of monochlorobenzene in contaminated groundwater treated in a constructed wetland

The degradation of monochlorobenzene (MCB) was assessed in a constructed wetland treating MCB contaminated groundwater using a detailed geochemical characterisation, stable isotope composition analysis and in situ microcosm experiments. A correlation between ferrous iron mobilisation, decreasing MCB concentration and enrichment in carbon isotope composition was visible at increasing distance from the inflow point, indicating biodegradation of MCB in the wetland. Additionally, in situ microcosm systems loaded with 13C-labelled MCB were deployed for the first time in sediments to investigate the biotransformation of MCB. Incorporation of 13C-labelled carbon derived from the MCB into bacterial fatty acids substantiated in situ degradation of MCB. The detection of 13C-labelled benzene indicated reductive dehalogenation of MCB. This integrated approach indicated the natural attenuation of the MCB in a wetland system. Further investigations are required to document and optimise the in situ biodegradation of MCB in constructed and natural wetland systems treating contaminated groundwater.     

Einfluß von 2,4-dinitrophenol auf die atmung und die Konzentration einiger metabolite bei embryonen des herings Clupea harengus

In rearing experiments with herring eggs (temperature=14.0°±0.1°C; salinity=15‰), oxygen consumption under normal conditions and after addition of 2,4-DNP (concentration=0.1 mM/l; pH=8.1) was measured over the period of embryonic development by means of the Wabburg-technique. Additionally, the concentration of low molecular sugars, polysaccharides, free amino-acids, and adenosintriphosphate (ATP) was determined. The oxygen consumption increases during embryonic development; this increase is not linear. Periods of high intensity of oxygen consumption are followed by others with only slight increase. Immediately before hatching, the respiration curve distincly declines (Fig. 1). Under the influence of 2,4-DNP (dinitrophenol), the embryos increase their respiration intensity after a short period of incubation. The maximum rise in percentage over the normal values reaches up to 400% at the beginning of gastrulation, falls to 50% even before the locking of the blastopore, and decreases slightly to about 30% until hatching. The immense decline in the percentage increase in respiration following the addition of 2,4-DNP at the end of the first day of development is caused by the rapid increase in normal respiration. After poisoning with DNP at different stages of development, the uncoupled respiration curves are normally almost equal. This holds both for the temporal position of the respiration maxima (about 12 to 24 h after poisoning), and for the absolute amounts of the increased respiration over the normal values (5 to 7 μl/h/100 embryos). Excluded from these regularly repeated findings are two stages of development: (1) the stage of epiboly after exceeding the yolk equator until shortly before locking of the blastopore (26 to 32 h after fertilization at 14°C); (2) the period at the end of the 4th day of development when the eyes become pigmented (100 to 120 h after fertilization). These two stages are characterized by the fact that, at the moment of poisoning, the normal respiration shows retarded activity. On the other hand, these two stages are well able to undergo periods of development in which long-living embryonic deformations can occur after uncoupling of respiration with 2,4-DNP. The content in low molecular sugars and polysaccharides decreases slightly in the course of embryonic development and, following the addition of 2,4-DNP, decreases considerably during the first 24 h. After 48 h, accelerated decomposition of carbohydrates continues. Under the influence of 2,4-DNP, the embryos metabolize more carbohydrates in 1 day than during the whole normal development period. The changeover of the metabolism to increased decomposition of carbohydrates can be explained as a dislocation of the energetic sources from the respiration chain to glycolytic phosphorylation. In accordance with these facts, the concentration of free amino-acids, almost equal during normal embryonic development, remains unchanged under the influence of 2,4-DNP.     

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of ¹³C, which complicates the evaluation of degradation. Therefore, the compound-specific isotope analysis was interpreted based on an isotope balance. The enrichment of the cumulative isotope composition of all chlorobenzenes indicated in situ biodegradation. Additionally, the relationship between hydrogeochemistry and degradation activity was investigated by principal component analysis underlining variable hydrogeochemical conditions associated with degradation activity at the plume scale. Although the complexity of the field site did not allow straightforward assessment of natural attenuation processes, the application of an integrative approach appeared relevant to characterize the in situ biodegradation potential.     

Average nanorough skin surface of the pilot whale (Globicephala melas, Delphinidae): considerations on the self-cleaning abilities based on nanoroughness

In aquatic environments, the biofouling process is assumed to initiate from the conditioning layer of absorbed organic carbon residues on wetted surfaces. Microfouling organisms attach to this conditioning layer, building up a biofilm on which further biofouling proceeds. In dolphins, biofouling reduces hydrodynamic efficiency and may negatively affect health if not managed. In the present study we examined the skin surface of the pilot whale (Globicephala melas). Employing cryo-scanning electron microscopic techniques combined with various sample preparations, the skin displayed an average nanorough surface characterized by a pattern of nanoridge-enclosed pores; the average pore size (approximately 0.20 µm²) was below the size of most marine biofouling organisms. Further, the implications of this type of surface to the self-cleaning abilities of the skin of pilot whales are discussed, based on reduced available space for biofouler attachment, the lack of any particular microniches as shelters for biofoulers, and the challenges of turbulent water flow and liquid-air interfaces during surfacing and jumping of the dolphin.     

Wirkungen von 2,4- und 2,5-Dinitrophenol auf die Embryonalentwicklung des Herings Clupea harengus

The biological effects of dinitrophenol (DNP) were tested on Clupea harengus eggs of Baltic spring and autumn spawners. Experimental water temperature was maintained at 10.8°C±0.2C° (experiment 1) and 11.8°C±0.2C° (experiments 2 and 3); salinity ranged between 14 and 16‰. Eggs were artificially fertilized 1 to 4 h after catching the parent individuals; they were attached to glass plates and incubated in 1 l aerated containers. Thirty, 48 and 55 h after fertilization, eggs were transferred to various test concentrations of DNP (dilutions of 2,4- and 2,5-DNP used are listed in Table 1). 2,4-Dinitrophenol is known as a true uncoupling reagent, which inhibits the phosphorylation of ADP. The effects of DNP on embryo activity, heart rate, rates of body malformations and mortality are studied. Embryo activity rose above control values between the 6th and 7th days of the incubation period in low DNP concentrations (0.01 to 0.05 mM/l), and heart activity deviated after 5 to 7 days from that of the controls. Mortality rate depended on inhibitor concentration and time of poisoning (Table 4). Various malformations of embryos were observed (anophthalmy, symmetrical and unilateral microphthalmy, curled bodies, de-differentiations, Fig. 7).