Biomarkers of toxicity in Clarias gariepinus exposed to sublethal concentrations of polycyclic aromatic hydrocarbons

Physiological, biochemical and histological indices in Clarias gariepinus broodstock, and teratogenic indices in embryos exposed to sublethal concentrations of naphthalene, phenanthrene and pyrene were investigated in 2014 using a static-renewal bioassay protocol. Phenanthrene (1.41 mg l^?1) was the most toxic, followed by pyrene (1.53 mg l^?1) and naphthalene (7.21 mg l^?1), based on 96 h LC50 values. Hepatosomatic indices were significantly higher in naphthalene- and pyrene-treated males compared with solvent controls, whereas fecundity in females was significantly lower by factors of 2.4 (naphthalene), 2.8 (phenanthrene) and 2.4 (pyrene), compared with controls. Catalase levels were lower in female phenanthrene-treated fish compared with controls. Histological alterations observed in PAH-treated fish include oedema, inflammatory cells, epithelial lifting and hyperplasia in the gills, vacuolation, haemosiderin pigments and sinusoidal congestion in the liver, and degenerated zona radiata in the ovary. Teratogenic effects were not observed, as evidenced by the lack of histological alterations in embryos spawned from pre-exposed broodstock. Sex-specific responses and the utility of biomarkers at cellular and individual levels of organisation are therefore demonstrated for holistic evaluations of polycyclic aromatic hydrocarbons in ecotoxicological studies.     

Seawater Sampling and Collection

This video documents methods for collecting coastal marine water samples and processing them for various downstream applications including biomass concentration, nucleic acid purification, cell abundance, nutrient and trace gas analyses. For today''s demonstration samples were collected from the deck of the HMS John Strickland operating in Saanich Inlet. An A-frame derrick, with a multi-purpose winch and cable system, is used in combination with Niskin or Go-Flo water sampling bottles. Conductivity, Temperature, and Depth (CTD) sensors are also used to sample the underlying water mass. To minimize outgassing, trace gas samples are collected first. Then, nutrients, water chemistry, and cell counts are determined. Finally, waters are collected for biomass filtration. The set-up and collection time for a single cast is ~1.5 hours at a maximum depth of 215 meters. Therefore, a total of 6 hours is generally needed to complete the collection series described here.Download video file.^{(98M, mp4)}     

Large Volume (20L+) Filtration of Coastal Seawater Samples

The workflow begins with the collection of coastal marine waters for downstream microbial community, nutrient and trace gas analyses. For this method, samples were collected from the deck of the HMS John Strickland operating in Saanich Inlet. This video documents large volume (≥20 L) filtration of microbial biomass, ranging between 0.22μm and 2.7μm in diameter, from the water column. Two 20L samples can be filtered simultaneously using a single pump unit equipped with four rotating heads. Filtration is done in the field on extended trips, or immediately upon return for day trips. It is important to record the amount of water passing through each sterivex filter unit. To prevent biofilm formation between sampling trips, all filtration equipment must be rinsed with dilute HCl and deionized water and autoclaved immediately after use. This procedure will take approximately 5 hours plus an additional hour for clean up.Download video file.^{(68M, mp4)}     

Microbial community dynamics in a seasonally anoxic fjord: Saanich Inlet, British Columbia

Dissolved oxygen concentration plays a major role in shaping biotic interactions and nutrient flows within marine ecosystems. Throughout the global ocean, regions of low dissolved oxygen concentration (hypoxia) are a common and expanding feature of the water column, with major feedback on productivity and greenhouse gas cycling. To better understand microbial diversity underlying biogeochemical transformations within oxygen-deficient oceanic waters, we monitored and quantified bacterial and archaeal community dynamics in relation to dissolved gases and nutrients during a seasonal stratification and deep water renewal cycle in Saanich Inlet, British Columbia, a seasonally anoxic fjord. A number of microbial groups partitioned within oxygen-deficient waters including Nitrospina and SAR324 affiliated with the δ- proteobacteria , SAR406 and γ- proteobacteria related to thiotrophic gill symbionts of deep-sea clams and mussels. Microbial diversity was highest within the hypoxic transition zone decreasing dramatically within anoxic basin waters and temporal patterns of niche partitioning were observed along defined gradients of oxygen and phosphate. These results provide a robust comparative phylogenetic framework for inferring systems metabolism of nitrogen, carbon and sulfur cycling within oxygen-deficient oceanic waters and establish Saanich Inlet as a tractable model for studying the response of microbial communities to changing levels of water column hypoxia.     

Microbial communities and their predicted metabolic functions in a desiccating acid salt lake

Extremophiles - The waters of Lake Magic in Western Australia are among the most geochemically extreme on Earth. This ephemeral saline lake is characterized by pH as low as 1.6 salinity as high as...     

Herpetomonas roitmani (Fiorini et al., 1989) N. Comb.: A Trypanosomatid with a Bacterium-like Endosymbiont in the Cytoplasm

The trypanosomatid previously described as Crithidia roitmani is characterized here at the ultrastructural and biochemical levels. The data indicates that the parasite belongs to the Herpetomonas genus, and we therefore suggest the flagellate to be denominated as Herpetomonas roitmani n. comb. Cladistic analysis of isoenzyme data generated by eight different enzymes showed that the parasite presented a distinct banding pattern and could be grouped with some Herpetomonas spp., but not with Crithidia spp., used as reference strains. Accordingly, when the parasites were grown for longer periods in Roitman's defined medium, expontaneous differentiation from promastigotes to opisthomastigotes (typical of the Herpetomonas genus) occurred. Transmission electron microscopy revealed the presence of bacterium-like endosymbionts in the cytoplasm of all evolutive forms of the parasite. All morphological alterations characteristic of endosymbiont-bearing trypanosomatids could be observed.     

Allosteric interactions within subsites of a monomeric enzyme: kinetics of fluorogenic substrates of PI-specific phospholipase C

Two novel water-soluble fluorescein myo-inositol phosphate (FLIP) substrates, butyl-FLIP and methyl-FLIP, were used to examine the kinetics and subsite interactions of Bacillus cereus phosphatidylinositol-specific phospholipase C. Butyl-FLIP exhibited sigmoidal kinetics when initial rates are plotted versus substrate concentration. The data fit a Hill coefficient of 1.2-1.5, suggesting an allosteric interaction between two sites. Two substrate molecules bind to this enzyme, one at the active site and one at a subsite, causing an increase in activity. The kinetic behavior is mathematically similar to that of well-known cooperative multimeric enzymes even though this phosphatidylinositol-specific phospholipase C is a small, monomeric enzyme. The less hydrophobic substrate, methyl-FLIP, binds only to the active site and not the activator site, and thus exhibits standard hyperbolic kinetics. An analytical expression is presented that accounts for the kinetics of both substrates in the absence and presence of a nonsubstrate short-chain phospholipid, dihexanoylphosphatidylcholine. The fluorogenic substrates detect activation at much lower concentrations of dihexanoylphosphatidylcholine than previously reported.     

辽宁地区毛腹种蝇的生态学调查

经过1963—64年在辽宁本溪新岭对毛腹种蝇Hylemya (Chionomyia)vetula(Zett,1838)进行生态学调查的结果,说明本种主要以成蝇越冬,多在室外活动;以蛹期越夏:10月上旬最早出现(17℃),秋末初冬大批羽化,10月中旬至11月中旬形成了第一个成蝇高峰,翌年3—4月是雌蝇产卵时期,活动频繁,雌蝇数量较多,形成了第二个成蝇高峰。于5月上旬成蝇绝迹(22℃),成蝇出现季节全长为7个月。 幼虫滋生于人粪和猪粪中。成蝇取食人粪、猪粪和牛粪。因此是一种在卫生上有一定重要性的蝇种。 三龄幼虫:肛板显然大形而向两侧突出,这点有别于种蝇属(Hylemya)的各巳知常见种的幼虫形态,但易被误认为花蝇属(Anthomyia)。它同七星花蝇(Anthomyia imbrida)和横带花蝇(Anthomyia illocata)相似,但是有以下区别:(1)小锥形的腹突、副腹突显然位于亚腹突一线的背方:(2)腹垫仅具等大的小刺,中央区无较大形的棘:(3)后肛疣仅有较大的丘状隆起,没有象花蝇属已知常见种幼虫的后肛疣那样尖而明显;(4)后气门间距约为后气门直径的1—2倍。     

本溪地区蚊虫初步调查

本溪地区的蚊虫过去未有过文献报告。我们于1957—1958年,在本溪地区(本溪市、本溪县)进行了蚊虫的初步调查。经两年的调查已发现的蚊种,有按蚊属1种,伊蚊属4种,库蚊属6种,共计11种。其名称如下: