Evaluation of bioremediation effectiveness on crude oil-contaminated sand

A treatability study was conducted using sea sand spiked with 3% or 6% (w/w) of Arabian light crude oil to determine the most effective bioremediation strategies for different levels of contamination. The sea sand used in the study was composed of gravel (0.1%), sand (89.0%), and silt and clay (10.9%). The water content of the sea sand was adjusted to 12.6% (w/w) for the study. Different combinations of the following treatments were applied to the sand in biometer flasks: the concentration of oil (3% or 6%), the concentration of a mixture of three oil-degrading microorganisms (Corynebacterium sp. IC-10, Sphingomonas sp. KH3-2 and Yarrowia sp. 180, 1x10(6) or 1x10(8) cells g-1 sand), the concentration of the surfactant Tween 80 (1 or 10 times the critical micelle concentration), and the addition of SRIF in a C:N:P ratio of 100:10:3. Three biometer flasks per combination of experimental conditions were incubated, and the performance of each treatment was examined by monitoring CO2 evolution, microbial activity, and oil degradation rate. The results suggest that the addition of inorganic nutrients accelerated the rate of CO2 evolution by a factor of 10. The application of oil-degrading microorganisms in a concentration greater than that of the indigenous population clearly increased biodegradation efficiency. The application of surfactant slightly enhanced the oil degradation rate in the contaminated sand treated with the higher concentration of oil-degrading microorganisms. The initial CO2 evolution rate was shown to efficiently evaluate the treatability test by providing significant data within a short period, which is critical for the rapid determination of the appropriate bioremediation approach. The measurements of microbial activity and crude oil degradation also confirmed the validity of the CO2 evolution rate as an appropriate criterion.     

Preparation conditions and swelling equilibria of biodegradable hydrogels prepared from microbial poly(γ-glutamic acid) and poly(ε-lysine)

Biodegradable hydrogels prepared by -irradiation from microbial poly(amino acid)s are reviewed. pH-sensitive hydrogels were prepared by means of -irradiation of poly(-glutamic acid) (PGA) produced byBacillus subtilis IFO3335 and poly(-lysine) (PL) produced byStreptomyces albulus in aqueous solutions. The preparation conditions, swelling equilibria, hydrolytic degradation, and enzymatic degradation of these hydrogels were studied. A hydrogel with a wide variety of swelling behaviors has been produced by -irradiation from a mixture solution of PGA and PL.Paper presented at the 4th International Workshop on Biodegradable Plastics and Polymers, October 11–14, 1995, Durham, New Hampshire, USA.     

Enhanced photocatalytic degradation of lindane using metal–semiconductor Zn@ZnO and ZnO/Ag nanostructures

To achieve enhanced photocatalytic activity for the degradation of lindane, we prepared metal–semiconductor composite nanoparticles (NPs). Zn@ZnO core–shell (CS) nanocomposites, calcined ZnO, and Ag-doped ZnO (ZnO/Ag) nanostructures were prepared using pulsed laser ablation in liquid, calcination, and photodeposition methods, respectively, without using surfactants or catalysts. The as-prepared catalysts were characterized by using X-ray diffraction (XRD), field-emission scanning electron microscopy, high-resolution transmission electron microscopy, ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence spectroscopy. In addition, elemental analysis was performed by energy dispersive X-ray spectroscopy. The obtained XRD and morphology results indicated good dispersion of Zn and Ag NPs on the surface of the ZnO nanostructures. Investigation of the photocatalytic degradation of lindane under UV–vis irradiation showed that Zn@ZnO CS nanocomposites exhibit higher photocatalytic activity than the other prepared samples. The maximum degradation rate of lindane was 99.5% in 40 min using Zn@ZnO CS nanocomposites. The radical trapping experiments verified that the hydroxyl radical (·OH) was the main reactive species for the degradation of lindane.     

Sea lamprey orient toward a source of a synthesized pheromone using odor-conditioned rheotaxis

Characterization of vertebrate chemo-orientation strategies over long distances is difficult because it is often not feasible to conduct highly controlled hypothesis-based experiments in natural environments. To overcome the challenge, we couple in-stream behavioral observations of female sea lampreys (Petromyzon marinus) orienting to plumes of a synthesized mating pheromone, 7α,12α,24-trihydroxy-5α-cholan-3-one-24-sulfate (3kPZS), and engineering algorithms to systematically test chemo-orientation hypotheses. In-stream field observations and simulated movements of female sea lampreys according to control algorithms support that odor-conditioned rheotaxis is a component of the mechanism used to track plumes of 3kPZS over hundreds of meters in flowing water. Simulated movements of female sea lampreys do not support that rheotaxis or klinotaxis alone is sufficient to enable the movement patterns displayed by females in locating 3kPZS sources in the experimental stream. Odor-conditioned rheotaxis may not only be effective at small spatial scales as previous described in crustaceans, but may also be effectively used by fishes over hundreds of meters. These results may prove useful for developing management strategies for the control of invasive species that exploit the odor-conditioned tracking behavior and for developing biologically inspired navigation strategies for robotic fish.     

不同植物人工湿地净化效果及基质微生物状况差异分析

为研究不同植物对人工湿地污染物净化效果和基质微生物状况的影响,采用序批式运行的沙培模拟人工湿地,探讨了菖蒲、香蒲、千屈菜、芦苇和白鹤芋5种湿地植物在不同HRT(水力停留时间,分别为1,3和5 d)下对模拟废水中TP,NH₄+-N和COD_Cr去除效果的影响,比较了不同植物类型模拟人工湿地中基质微生物的数量差异. 结果表明,不同植物系统对污染物的去除随HRT延长逐渐提高,HRT为5 d时各植物系统对污染物的去除效果最佳.TP,NH₄+-N和COD_Cr的最高去除率分别达90.4%,61.7%和96.4%.相对于其他试验系统,菖蒲系统对各污染指标均具有最优的去除效果. 植物种类对基质微生物数量的影响无显著差异.研究还发现,各系统中亚硝酸细菌数量与NH₄+-N去除率之间呈显著相关.      

Glucosinolates and other metabolites in the leaves of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> from natural populations and their effects on a generalist and a specialist herbivore

Because many secondary metabolites in plants act as defense against herbivores it has been postulated that these compounds have evolved under selective pressure by insect herbivores. One explanation for the within-species variation in metabolite patterns in a particular species is that different populations are under selection by different herbivores. We tested this hypothesis, using Arabidopsis thaliana plants that originated from dune and inland areas. We analyzed Arabidopsis thaliana leaves using NMR spectroscopy and multivariate data analysis. Major differences in chemical composition were found in water-methanol fractions and were due to higher concentrations of sinigrin and fumaric acid in dune plants. Inland plants showed lower levels of glucose. Quantitative analysis of glucosinolates was performed with HPLC. Individual plants and populations demonstrated differences in glucosinolate composition and concentration. In growth chamber experiments, the generalist herbivore, Spodoptera exigua grew significantly better on the inland plants, while the specialist herbivore Plutella xylostella performed equally well on plants of both origins. Aliphatic glucosinolate as well as total glucosinolate concentrations negatively correlated with larval mass of Spodoptera exigua. No significant correlations, however, were found between larval mass of Plutella xylostella and glucosinolates in the leaves. A specialist and a generalist herbivore were responding differently to plant secondary chemistry, as was also found in several other studies. This is an important indication that differences in glucosinolate concentrations among populations may result from differential selection by different guilds of herbivores.     

Dynamic female preference for multiple signals in <Emphasis Type="Italic">Rhinogobius brunneus</Emphasis>

Many species base their choice of mates on multiple signals which provide them with different kinds of information. Choosers may assess the signals together to evaluate the overall quality of potential mates, but individuals often pay attention to different signals in different contexts. In Rhinogobius brunneus, a fish displaying exclusive male parental care, females generally prefer males showing larger first dorsal fins (FDF) and more active courtship displays as mates. Females choosing a mate usually initially assess the FDF and later utilize courtship for the final decision. In our experiments, females with different hunger states used different signals when selecting mates. Females in both hunger states preferred males with larger FDF in the first stage. In the second stage, well-fed females showed highly repeatable choice, whereas poorly fed females responded only to variation in the courtship activity of males. The males preferred by poorly fed females exhibited significantly higher offspring survival than nonpreferred males. Under conditions of food shortage, males allocate more energy to future reproduction at the expense of the present brood, and females may prioritize signals predictive of offspring survivorship over signals reflecting other aspects in male quality to minimize the losses in direct benefits. We conclude that R. brunneus females may employ information from both signals but dynamically adjust their prioritization of each signal to current conditions to ensure the choice that is currently most adaptive.     

A comparative study of aggressiveness in eastern North American field cricket species (genus <Emphasis Type="Italic">Gryllus</Emphasis>)

To understand the variation in aggressiveness and factors important for contest outcome, we quantified and compared agonistic interactions of four field cricket species in eastern North America: Gryllus fultoni (Orthoptera; Gryllidae), G. vernalis, G. pennsylvanicus, and G. rubens. The most aggressive behavior that we observed, the grapple, was frequently displayed in agonistic trials of G. pennsylvanicus and G. rubens. By contrast, we never observed this behavior in trials involving G. fultoni and G. vernalis. Consequently, species was the only significant variable affecting the variation in aggressiveness, whereas size difference, age difference, and contest duration had no significant effect. In species with high levels of aggressiveness, G. pennsylvanicus and G. rubens, the factors that might be indicative of resource holding potential such as size or age difference seemed to be significant for contest outcome. In species with low levels of aggressiveness, G. fultoni and G. vernalis, however, there were indications that contest outcomes were determined by aggressiveness itself rather than the size and age differences between opponents. Markov chain analyses revealed that the difference in aggressiveness between species with high and low levels of aggressiveness lay in a sequence of escalating behaviors: antennal fencing, mandible flare, and grapple. The escalated state of aggressiveness characterized by this behavioral sequence in G. pennsylvanicus and G. rubens seems to be the ancestral state in the North American Gryllus phylogeny. We argue that the loss of a tendency to use burrows in G. fultoni and G. vernalis might be related to low levels of aggressiveness in these species.     

Repeated-dose toxicity attributed to aluminum nanoparticles following 28-day oral administration,particularly on gene expression in mouse brain

Nanotechnology is a rapidly growing industry that has elicited much concern due to the lack of available toxicity data. Aluminum oxide nanoparticles (AlNP) were listed as a high-priority group in the Organization for Economic Co-operation and Development (OECD) Steering Group for Test Guidelines. In this study, AlNP 35 ± 18.8 nm in size were administered daily at doses of 15, 30, or 60 mg k^?1 for 28 days. A significant decrease in white blood cells (WBC), neutrophils, lymphocytes, and monocytes was observed in the group treated with 60 mg kg^?1 of AlNP, accompanied by a significant increase in platelets. The concentration of aluminum (Al) rose significantly in the thymus, lung, and brain of the group treated with 60 mg kg^?1 of AlNP. However, no significant changes in histopathology were observed. The expression for feeding behavior, energy expenditure, and neurodegeneration-related genes were up-regulated more than twofold by 60 mg kg^?1 AlNP. Consequently, data suggest that exposure to AlNP may result in adverse health effects, including but not limited to growth inhibition, immunosuppression, and neurodegeneration.