Importance of nonindigenous harpacticoids (Crustacea: Copepoda) decrease with depth in Lake Ontario

Harpacticoid copepods can be a substantial component of the meiobenthic community in lakes and serve an ecological role as detritivores. Here we present the first species-level lake-wide quantitative assessment of the harpacticoid assemblage of Lake Ontario with emphasis on the status of nonindigenous species. Additionally, we provide COI-5P sequences of harpacticoid taxa through Barcode of Life Data System (BOLD). Harpacticoids were collected at depths from 0.1 to 184 m and from a range of substrates from August to September 2018 as part of the Cooperative Science and Monitoring Initiative (CSMI) offshore benthic survey. Twenty-six meiobenthic samples were analyzed using microscopy for community composition analysis of harpacticoids. We found thirteen indigenous and three nonindigenous species of harpacticoid, with the introduced species dominating at shallow depths. The community transitioned from nonindigenous to indigenous species dominance as depth increased. Nonindigenous species accounted for 79% of the community (by abundance) at depths <20 m, 55% from 20 to 40 m, and only 24% at depths >40 m. The nonindigenous species encountered included the first detections of Schizopera borutzkyi (Monchenko, 1967) and Heteropsyllus nunni (Coull, 1975) from Lake Ontario. S. borutzkyi was the most abundant harpacticoid species in the lake, approaching a maximum density of 50,000/m² and a lake-wide average density of 7,900/m². Numerically important indigenous species included Bryocamptus nivalis (Willey, 1925), Canthocamptus robertcokeri (Wilson, 1958), Canthocamptus staphylinoides (Pearse, 1905), and Moraria cristata (Chappuis, 1929). The prevalence of nonindigenous harpacticoids in the meiobenthos of Lake Ontario suggests further investigations of Great Lakes meiofauna communities are warranted.     

A new algorithm for analysis of the homology in protein primary structure

A new algorithm for analysis of the homology and genetic semihomology in protein sequence is described. It assumes the close relation between the compared amino acids and their codons in related proteins. The algorithm is based on the network of the genetic relationship between amino acids and, thus differs from the commonly used statistical matrices. The results obtained by using this method are more comprehensive than used at present, and reflect the actual mechanism of protein differentiation and evolution. They concern: (1) location of homologous and semihomologous sites in compared proteins; (2) precise estimation of insertion/deletion gaps in non-homologous fragments; (3) analysis of internal homology and semihomology; (4) precise location of domains in multidomain proteins; (5) estimation of genetic code of non-homologous fragments; (6) construction of genetic probes; (7) studies on differentiation processes among related proteins; (8) estimation of the degree of relationship among related proteins; (9) studies on the evolution mechanism within homologous protein families and (10) confirmation of actual relationship of sequences showing low degree of homology.     

An industrial SR-TXRF facility at ESRF

A TXRF industrial facility for the mapping of trace impurities on the surface of 300-mm Silicon wafers is presently in the construction phase and will start the commissioning phase at the end of 1998. The elements to be detected range from Na to Hg with a target routine detection limit of 10⁸ at/cm² and the capability of mapping the surface of 300-mm wafer with a resolution of 500 pixels and a throughput of three wafers/h.     

Direct enumeration of Escherichia coli and enteric bacteria in water,beverages and sprouts by 16S rRNA in situ hybridization

A fluorescent oligonucleotide probe complementary to a published 16S ribosomal RNA sequence ofEscherichia coli was used for in situ hybridization on membrane filters for direct enumeration of cells. The direct epifluorescent filter technique (DEFT) was modified by performing a 2-h oligonucleotide hybridization on intact cells collected on a membrane filter surface (‘oligo-DEFT’), instead of the traditional acridine orange staining. The filter was examined by epifluorescence microscopy, and digital image analysis was used for the cell enumeration. Oligo-DEFT counts were linear over the range of 10³–10⁶cells ml⁻¹and correlated with DEFT counts (r=0·99). The oligo-DEFT detection limit was approximately 1 cell ml⁻¹. Oligo-DEFT counts correlated with standard coliform counts by membrane filtration or plating on selective media for analysis of water and beverages artificially inoculated with E. coli. Heat inactivation of the cells did not destroy their reactivity in the oligo-DEFT. Natural coliform populations in aquarium water were countable in the oligo-DEFT after a 90-min incubation of the filter on nutrient agar before the hybridization step, which allowed the dormant cells to increase their rRNA content. Natural populations in bean sprouts were countable directly, without having to perform the incubation before hybridization.     

Comparison between lipid and protein oxidation progress in the tail and claw muscles of signal crayfish (Pacifastacus leniusculus)

Microbial activity and then oxidation progress are the most important freshness indicators during post-mortem. In this study, we monitored proteomic and microbial changes, as well as biochemical degradation, in the tail and claw muscles of crayfish stored for 12 days at +4 °C. One specified protein band at 107 kDa in the claw muscle and two specified protein bands in the tail muscle at 140 and 36–40 kDa were identified. Western blotting indicated a higher amount of oxidised proteins in the tail compared to the claw muscle. Tail muscle showed higher oxidation progress and calpain activity than claw one. Both muscles were spoiled after 12 days with respect to total viable counts. In the first days, calpain activity is the main reason for protein degradation, while protein oxidation dominates for the rest of the time. Lipid–protein oxidation progress showed probably, protein oxidation started earlier than lipid oxidation in both muscles.     

氮、磷对缺刻蚁形藻生长、总脂及花生四烯酸积累的影响

目的:研究缺刻蚁形藻(Myrmecia incisa)在4种氮、磷质量浓度条件下的生长和总脂(TL)及花生四烯酸(AA)含量,以及在低氮和低磷条件下的脂肪酸组成。方法:采用BG-11培养基和Φ6×60cm柱状光生物反应器培养缺刻蚁形藻,利用有机溶剂提取脂类物质,通过气相色谱-质谱仪分析脂肪酸的组成。结果:在300～1500mg/L的硝酸钠质量浓度范围内,氮质量浓度的改变对缺刻蚁形藻的生物量影响不明显,不同氮质量浓度条件下的最终生物量在2.10～2.40g/L之间。低氮质量浓度条件下TL和AA含量最大,分别为藻粉干质量的27%和总脂肪酸(TFA)的9.04%,其中AA占藻体干质量的3.16%。不同磷质量浓度对缺刻蚁形藻的生长影响显著,低磷质量浓度明显抑制藻的生长,其最终生物量在0.98～2.47g/L之间。在质量浓度8～20mg/L的磷酸氢二钾条件下,藻的TL含量没有明显变化,为20%左右。结论:TL与氮、磷质量浓度呈明显负相关关系,低氮比低磷条件更有利于AA的积累。     

东海原甲藻对尿素的吸收动力学与利用特性

以中国东海大规模赤潮发生海区的东海原甲藻为实验材料,研究其对尿素的吸收动力学和利用特性.结果发现,东海原甲藻对尿素N的最大吸收速率(3.184/h)高于氨态N(2.800/h);东海原甲藻在以CO(NH2)2为唯一氮源时的最大比生长速率(0.685/d)超过NO3-(0.663/d);虽然东海原甲藻对NO3-和NH4+的亲和力略高于CO(NH2)2,但由于东海原甲藻具备快速吸收和利用尿素的能力,在无机氮含量较低且尿素丰富的近岸水体中具有竞争优势.指出尿素含量的上升可能是引发东海原甲藻赤潮的重要诱因.     

Patterns in spatial use of land-locked Atlantic salmon (Salmo salar) in a large lake

Understanding the spatial use of reintroduced fish is useful for fisheries management and evaluating restoration success. Atlantic salmon (Salmo salar) were reintroduced into Lake Ontario in the 1990s; however, the movement ecology of these land-locked fish is unknown. Using acoustic telemetry and Floy tag mark-recaptures, we examined seasonal home range and space use of Atlantic salmon in Lake Ontario. Hatchery-raised adult Atlantic salmon were tagged with acoustic transmitters (n = 14; 8 with depth sensors) or Floy tags (n = 1915) and released. Both acoustic telemetry and Floy tag recaptures (n = 90) indicated cross lake movements, and home ranges encompassed nearly the entire lake in summer but was smaller in winter. Movements were nearshore (<2 km from shore) from spring to summer at ～20 m bathymetric depths, with movements closer to shore in the fall, and further offshore (～5.5 km from shore and 45 m bathymetric depths) in winter. Depth use was relatively shallow (<4 m) with occasional deeper dives (max = 28.5 m), and small diel vertical movements (1–5 m), moving deeper during daytime, consistent with ocean movements of Atlantic salmon. There appears to be spatial segregation among Atlantic salmon and other Lake Ontario salmonids, however, overlap likely occurs in nearshore waters during the spring. Wide-ranging movements of Atlantic salmon in binational (Canada/USA) waters reflects the importance of government agencies collaborating to ensure sustainable fisheries and the coordination of species restoration activities. This is the first study to provide detailed spatial use of Lake Ontario Atlantic salmon to assist in the management of this reintroduced species.     

Incorporated ZnO onto nano clinoptilolite particles as the active centers in the photodegradation of phenylhydrazine

ZnO was incorporated into nano particles of clinoptiloite by ion exchanging the zeolite in a zinc nitrate aqueous solution followed by calcinations process. All raw and modified samples were characterized by XRD, FT-IR, DRS, TG-DTG, SEM, BET and TEM. The prepared catalyst was used in the photocatalytic degradation of phenylhydrazine (PHZ) and the best experimental parameters were obtained as: 0.25 g L⁻¹ of the catalyst, 20 ppm pollutant concentration and pH = 8. The degradation extent was monitored by UV–vis spectroscopy and the results were confirmed by HPLC and the chemical oxygen demand (COD).