Alteration of gene expression profiles in the brain of Japanese medaka (Oryzias latipes) exposed to KC-400 or PCB126

Polychlorinated biphenyls (PCBs) are known as neurotoxic chemicals and possibly alter animal behavior. We previously reported that PCB-exposure induced abnormal schooling behavior in Japanese medaka (Oryzias latipes). This abnormal behavior might be caused by the functional alteration of central or terminal nervous system. To understand the mechanism(s) of behavioral change by PCB-exposure, we analyzed the gene expression profiles in the brain of medaka exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB126) or a PCB mixture (Kanechlor-400: KC-400) using a cDNA microarray that we constructed. Twelve FLF-II strain medaka (six individuals per treatment) were dietary exposed to PCB126 (0.01 microg/g b.w./day) or KC-400 (1 microg/g b.w./day) for three weeks. For the control, six fish were fed a control diet. After the exposure period, fish were dissected, and the brain samples were collected. The samples from control fish were pooled and used as a common reference in the microarray experiment. Microarray data were normalized by the LOWESS method, and we screened the genes whose expression levels were altered more than 1.5-fold. Gene expression profiling showed 97 down-regulated and 379 up-regulated genes in the brain of medaka exposed to PCB126. KC-400 exposure suppressed 15 genes and induced 266 genes in medaka brain. Among these genes, the expression levels of 7 and 188 genes were commonly down- or up-regulated, respectively in both treatment groups. On the other hand, 31 gene expressions were significantly different between PCB126 and KC-400 treatment groups, and three out of 31 genes were received opposite effects. In addition, the microarray data showed that thyroid hormone-responsive genes were up-regulated by PCB-exposure, which may imply that PCBs or their metabolites mimic thyroid hormone effects in the brain of PCB-exposed medaka.     

青藏高原那曲地区冰雹天气系统中的大气电场

利用1998年4～9月间进行的GAME-TIBET青藏高原云和降水的多普勒雷达及大气平均电场加强期观测实验资料, 对青藏高原那曲地区的冰雹天气系统中的大气电场作了定量观测和研究.结果表明: 在降雹过程中大气电场强度基本上均为负值, 其峰值也均强于-22 kVm-1; 在降雹过程中随着降雹时间的临近, 大气电场强度不断增强, 但降雹开始时大气电场强度并未达到其峰值, 峰值出现的时刻比开始降雹的时刻略有滞后; 在各降雹日中, 较强的大气电场强度基本上对应着各冰雹谱分布段较多的冰雹数目, 而这种较好的相关在各谱分布段上都表现出来; 随着降雹时间的临近, 每5 min闪电频数不断增强.在开始降雹时每5 min闪电频数平均达到43, 峰值的出现时刻略滞后于开始降雹的时刻, 这一滞后时间一般平均在3 min左右; 在降雹过程中, 单位面积中的冰雹数目与对应时段内总闪电数有着较好的对数关系, 相关系数R为0.954 0.在降雹过程的时间序列上, 冰雹云成熟期过后, 总闪电次数与冰雹降雹率成反相关.     

Groundwater dynamics of Fongafale Islet, Funafuti Atoll, Tuvalu

Geoelectric and hydrologic surveys during spring tides revealed the spatiotemporal distribution of groundwater quality produced by tidal forcing in Fongafale Islet, Funafuti Atoll, Tuvalu. The observed low resistivity showed that saline water largely immersed the surficial Holocene aquifer, indicating that there is no thick freshwater lens in Fongafale Islet, unlike in other atoll islands of comparable size. Half of the islet was constructed by reclaiming the original swamp with porous, highly permeable coral blocks; this reclaimed area should not be considered as part of the islet width for calculation of the expected thickness of the freshwater lens. The degree of aquifer salinization depends on the topographic characteristics and the hydrologic controls on the inland propagation of the tidal forcing. Large changes in bulk resistivity and the electrical conductivity of groundwater from wells indicate that periodic salinization in phase with the semidiurnal tides was occurring widely, especially in areas at lower elevation than the high-tide level and in reclaimed areas with high permeability. Thin sheets of nearly fresh and brackish water were observed in the surficial aquifer in areas above the high-tide level and in taro swamps, respectively. The thinness of the brackish and freshwater sheets suggests that the taro swamps and the fresh groundwater resources of the islet are highly vulnerable to salinization from anticipated sea-level rise. An understanding of the inherent geologic and topographic features of an atoll is necessary to evaluate the groundwater resources of the atoll and assess the vulnerability of its water resources to climate change.     

Comprehensive assessment of heavy metal contamination in sediment of the Pearl River Estuary and adjacent shelf

Total metal concentrations (Cr, Ni, Cu, Zn, and Pb), acid volatile sulfide and simultaneously extracted metals (AVS-SEM), and heavy metal fractionation were used to assess the heavy metals contamination status and ecological risk in the sediments of the Pearl River Estuary (PRE) and adjacent shelf. Elevated concentrations at estuarine sites and lower concentrations at adjacent shelf sites are observed, especially for Cu and Zn. Within the PRE, the concentration of heavy metals in the western shore was mostly higher than that in the middle shore. The metals from anthropogenic sources mainly occur in the labile fraction and may be taken up by organisms as the environmental parameters change. A combination of total metal concentrations, metal contamination index and sequential extraction analysis is necessary to get the comprehensive information on the baseline, anthropogenic discharge and bioavailability of heavy metals.     

Occurrence of DDA in DDT-contaminated sediments of the Southern California Bight

DDT, DDE and some additional lipophilic derivatives are recognized contaminants in sediments of Southern California Bight (SCB). Only about 10% of total DDTs discharged into the SCB are accounted for using available monitoring data (sediment, water, and biota). DDA represented up to 0.03% DDTs (DDT/DDE/DDD) in SCB surface sediments (top 2 cm) in amounts up to 76 μg DDA/kg dry weight. Highest DDA levels were found where DDT and DDD levels were maximal at the primary wastewater outfall indicating a natural precursor-product relationship for DDT and DDA. Still culture of SCB sediment revealed limited DDA formation following DDT fortification. DDA residues have also been found in contaminated Long Island, NY sediments provided by USGS. The formation of DDA and its potential release from sediments may be significant in resolution of uncertainties concerning the natural recovery of sediments in DDT-contaminated environments.     

Oxidative stress, genotoxicity and histopathology biomarker responses in mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) liver from Bizerte Lagoon (Tunisia)

The aim of the study was to evaluate the impact of environmental contaminants on oxidative stress, genotoxic and histopathologic biomarkers in liver of mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) collected from a polluted coastal lagoon (Bizerte Lagoon) in comparison to a reference site (the Mediterranean Sea). Antioxidant enzyme activities were lower in fish from the polluted site compared with fish from the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. DNA damage was higher in both fish species from the contaminated site indicating genotoxic effects. The liver histopathological analysis revealed alterations in fish from Bizerte Lagoon. Hepatocytes from both fish species featured extensive lipid-type vacuolation and membrane disruption. Results suggest that the selected biomarkers in both fish species are useful for the assessment of pollution impacts in coastal environments influenced by multiple pollution sources.     

Assessing a bioremediation strategy in a shallow coastal system affected by a fish farm culture--application of GIS and shellfish dynamic models in the Rio San Pedro, SW Spain

An integrated multi-trophic aquaculture assessment for Pacific oyster (Crassostrea gigas) aquaculture as a bioremediation strategy in areas impacted by fish farm effluents in Rio San Pedro was assessed by combining geographic information system with carrying capacity models. Sites of 0.44 km(2) were evaluated considering constraints; physical factors, growth and survival factors, environmental quality factors, water and sediment quality criteria, factor suitability ranges, and Multi-Criteria Evaluation. Isleta and Flamenco are promising sites for oyster production, and Dorada is of marginal interest. Carbon and nitrogen removal from the water by algae and through detritus filtration was estimated. The biodeposition of organic material from longline leases was found to have little negative impact on sediment. The eutrophication results indicate that phytoplankton removal had a positive impact on water quality at the Dorada. This case study quantified the direct profitability and bioremediative environmental service advantages that fish-shellfish farms can have relative to fish monocultures.     

Water quality assessment using satellite-derived chlorophyll-a within the European directives, in the southeastern Bay of Biscay

The implementation of water quality European Directives requires an intensification of water quality monitoring, within the limits of the Exclusive Economic Zone. Remote sensing technologies can provide a valuable tool for frequent, synoptic, water-quality observations, over large areas. The aim of this study is to assess the ecological status of Basque coastal water bodies using satellite imagery from MODIS sensor, together with optical and chlorophyll-ain situ measurements. Thus, sea surface satellite-derived chl-a algorithms, the OC3 M, OC5 and a Local empirical algorithm, were compared against in situ measurements using satellite in situ match-ups, 90th Percentile (P90) monthly values for the 2005-2010 period. The OC5 algorithm corresponded most accurately with in situ measurements performed in the area, hence, it was selected. A P90 chlorophyll-a map was created with this algorithm to apply the classification scheme required by the directives. The classification of water bodies, based upon satellite-derived chlorophyll-a, could improve considerably the assessment of water quality.     

Metazooplankton communities in the Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia): Spatiotemporal variations and trophic relationships

Metazooplankton abundance, biomass (<80μm, 200-500μm and >500μm) and community structure in the Ahe atoll were studied together with their relationships with environmental factors (temperature, salinity, wind) and trophic factors (phytoplankton, bacteria, heterotrophic nanoflagellates (HNF) and ciliates) during three periods in 2008-2009. Meroplankton, mainly bivalve and gastropod larvae, was dominant. Holoplankton was dominated by copepods, the main species being Oithona spp., Paracalanus parvus, Clausocalanus spp., Corycaeus spp., Acartia fossae and Undinula vulgaris. The results suggest a clear wind influence on the structure and horizontal distribution of the zooplankton communities. The metazooplankton appeared to be controlled mainly by food resources, suggesting a bottom-up control. The low nanophytoplankton biomass in contrast to the high abundance of picophytoplankton, HNF and nano-particle grazers (mainly Oithona spp., Paracalanus and bivalve larvae) highlighted the importance of the microbial loop in the food web.