2-Ethyl-3-methylmaleimide in Tokyo Bay Sediments Providing the First Evidence for its Formation from Chlorophylls in the Present Photic and Oxygenic Zone

Tokyo Bay bottom sediments were analyzed for 2-ethyl-3-methylmaleimide, a degradation product of chlorophylls, which has been detected in ancient sediments. It was found in all sediments examined in concentrations of about 1 to 15 nmol/g- of dried sediment, and it was shown to be preserved for 100 years in the sediments. Its depth distribution agreed with that of the reported total organic carbon content of the sediments, reflecting a change in primary productivity. We concluded that this maleimide was produced under photic and oxygenic conditions in nature before the incorporation of photosynthesizing organisms into sediments.     

Distribution and contamination assessment of arsenic and mercury in surface sediments from the intertidal zone of Yantai Sishili Bay,China

Sixty surface sediment samples from the intertidal zone of Yantai Sishili Bay (YSB) have been analyzed for arsenic (As) and mercury (Hg) to evaluate their contamination levels and potential ecological risks. Concentrations of As and Hg ranged from 7.01–23.56 and 0.00–0.01 μg g^?1 in the dry season; during the wet season, the corresponding data were 1.44–6.17 and 0.00–0.02 μg g^?1. The geoaccumulation index (I_geo) and potential ecological risk index (E_rⁱ) were used to conduct a pollution assessment. The results demonstrated that the intertidal zone of YSB has good sediment quality and that As and Hg are not likely to cause negative environmental impacts in the region.     

Frost formation in the ecotonal zone and its role for release of nutrients

In winter, the littoral substrate of ecotonal zones along north Swedish rivers and lakes freezes. Even if the littoral is flooded at freeze-up, the ice freezes solid to the shore substrate due to low temperature combined with a gradual decrease in water level during winter. Frost conditions were studied during an 8-year period along eight littoral transects in the River Vindelälven and adjacent riverside lagoons. Heavy frost heave with formation of needle ice was observed in several places.Nutrient release was suggested to take place due to the frost process. Sediment was taken to a laboratory experiment where samples with sediment and water were kept under unfrozen and frozen conditions during six months. N (total-N) and Ca were significantly released to the water, while P (total-P) did not show any clear movement from the frozen sediment.The results indicate that frost processes in ecotonal zones are involved in the movement of nutrients between sediment and water.     

Rotifer assemblages in the Neva Bay,Russia: principles of formation,present state and perspectives

A comparative study of species composition, abundance and spatial distribution of the rotifers of Neva Bay (Gulf of Finland, Baltic Sea), between 1982–1993, was carried out. The rotifer fauna in the central basin of Neva Bay is determined by and originates in Lake Ladoga and is very similar to that of the Neva River. High turbidity and effect of winds affecting water residence time influence composition and density of rotifers in this shallow estuary. The importance of rotifer assemblages for evaluation of the quality of the estuary is discussed.     

大亚湾冬季沉积物中叶绿素含量与分布

2012年2月(冬季)对大亚湾海域沉积物叶绿素a (Chl-a)及其降解产物脱镁叶绿酸( Pha-a)的含量与分布进行了研究,并探讨了环境因子(水深、温度、透明度、粒度、营养盐、TOC)对表层沉积物Chl-a含量分布的影响.结果表明:Chl-a和Pha-a是同源的,随沉积物深度增加二者皆呈递减趋势,个别站位Chl-a和Pha-a出现许多小突跃,这可能与生物扰动和环境变化有关;表层(0～l cm)Chl-a和Pha-a的含量变化范围分别为0.98 ～ 1.55μg·g-1和3.97～6.65 μg·g-1,平均含量分别为1.24和5.55 μg ·g-1.Chl-a含量变化是各种环境因子共同作用的结果,其中最主要的影响因素是沉积物底质颗粒的大小,高比例砂含量的底质能为底栖藻类提供更多的生存空间,但不利于沉积物中Pha-a的保存;比较了沉积物与上层水体中平均Chl-a相对含量,并与其他海域相比较,发现该海域沉积物中Chl-a含量较高,与水体Chl-a含量比值为50.28％ ～ 150.79％,近海沉积物中底栖初级生产力不可忽视.     

锦州湾及附近河口沉积物中砷含量、分布及形态

对葫芦岛3条河流和锦州湾水体、沉积物中As的含量、分布和形态进行了研究。结果表明：葫芦岛的连山河和五里河未受到明显的As污染,沉积物总As含量低于10 mg·kg^-1,河水As含量低于10 μg·L^-1,茨山河下游紧邻葫芦岛锌厂,受到了一定程度的As污染,沉积物As含量达75.2 mg·kg^-1;五里河口区As污染非常严重,锌厂在该区排污口处沉积物As含量高达3176.1 mg·kg^-1,超过国家沉积物As标准158倍;受锌厂排污的影响,锦州湾As污染也很严重,沉积物中As最高含量达到569.5 mg·kg^-1,沉积物和孔隙水含量在剖面上具有相似的变化趋势,表明孔隙水As含量主要受沉积物As含量影响;锦州湾沉积物中As主要以可交换态存在,残渣态次之,盐酸提取态最少,表明锦州湾沉积物中As的活性很强,有大量的可交换态As随时会进入上覆水体,是重要的As释放源,而铁对As行为的影响占次要地位;沉积物中大量As的释放可能会对葫芦岛和锦州湾地区生态系统造成严重的威胁。     

Phosphorus recycling in lakes: evidence from large limnetic enclosures for the importance of shallow sediments

• 1 The dynamics of phosphorus in large field enclosures are described from a series of experimental manipulations directed primarily to the study of phytoplankton populations. The enclosures were similar in size but differed in their depth contours. The aim of the present analysis was to detect systematic differences in the phosphorus budgets of deep and shallow systems.
• 2 The sequence of events in each of six year-long experiments is described in terms of algal production. The values are compared with water-column measurements of total phosphorus (TP), the reactive fraction (SRP) and changes in the particulate fraction (PP, assumed to be TP minus SRP). Stoichiometric ratios for larger phytoplankton crops were in the range 85–110 C/P (molar).
• 3 The annual aggregate of new carbon produced in the two uniformly deep enclosures (11.5 m) in relation to the phosphorus supplied was also remarkably close to Redfield stoichiometry, with between 87 and 97mol C yielded per mol P added. However, in the graded enclosure (< 4–13.5 m), the yield was up to twice as great (maximum: 197 mol C mol^-1 P available).
• 4 There are two possible mechanisms. A graded surface permits a greater area of sediment to be in contact with the hypolimnion and for the sediment oxygen demand to deplete a greater hypolimnetic volume; the associated fall in redox would have been adequate to explain the observed increment of dissolved phosphorus to the hypolimnion, associated with the Einsele–Mortimer model (ferric → ferrous iron reduction). There was no clear evidence that this phosphorus supported autotrophic production until late in the year.
• 5 The alternative mechanism is based on the association of phosphorus ‘injection’ to the epilimnion during wind-mixed episodes, when the enhanced shear stress on shallow sediments resuspends fine, superficial deposits and their interstitial waters into the full circulation. Circumstantial evidence suggests this second pathway predominated in the graded enclosure but was ineffective in the uniformly deep enclosures.
• 6 The role of mechanical, aerobic phosphorus cycling in the nutrient economy of lakes, especially small or shallow ones, may have been underestimated in the past but it must be considered when evaluating any proposal to reduce the external nutrient loads to lakes.

     

Microplankton and its function in a zone of shallow hydrothermal activity:the Craternaya Bay, Kurile Islands

Biomass and productivity of microplankton were measured in theCraternaya Bay (Kurile Islands), which is influenced by hydrothermalactivity and volcanic heating. The hydrothermal fields are situatedaround its shores and underwater within the 0–20 m depth.A dense ‘bloom’ of photoautotrophic microplanktonwas observed there, dominated by diatoms, phytoflagellates andthe symbiont-containing ciliate Mesodinium rubrum. The biomassof these ciliates attained 3–11 g m^-3 in the upper waterlayer. The total biomass of the phototrophic microplankton reached30–46 g m^-3. The primary production in the water columnwas, correspondingly, enormously high: 6–10 g C m^-2 day^-1.The depth of the euphotic zone was 7 m. Pelagic photosynthesiswas inhibited in the upper 0–1 m by the spreading of alayer of low-salinity hydrothermal water. The numerical densityof bacterioplankton in the upper zone of the water column variedfrom 1 x 10⁶ to 2.9 x 10⁶ cells ml^-1, and its wet biomass from250 to 750 mg m^-3. Its production varied at stations from 70to 390 mg m^-3 day^-1. Chemosynthesis contributed up to 30% ofthis production in the sites neighbouring the hydrothermal vents.Outside their direct impact however, its share was negligible.The biomass of heterotrophic planktonic ciliates varied from30 to 270 mg m^-3. The mechanisms of possible influence of shallowvolcanic activity on development and function of microplanktonin the Craternaya Bay is discussed.     

The dark side of the hyporheic zone: depth profiles of nitrogen and its processing in stream sediments

1. Although it is well known that sediments can be hot spots for nitrogen transformation in streams, many previous studies have confined measurements of denitrification and nitrate retention to shallow sediments (<5 cm deep). We determined the extent of nitrate processing in deeper sediments of a sand plains stream (Emmons Creek) by measuring denitrification in core sections to a depth of 25 cm and by assessing vertical nitrate profiles, with peepers and piezometers, to a depth of 70 cm. 2. Denitrification rates of sediment slurries based on acetylene block were higher in shallower core sections. However, core sections deeper than 5 cm accounted for 68% of the mean depth‐integrated denitrification rate. 3. Vertical hydraulic gradient and vertical profiles of pore water chloride concentration suggested that deep ground water upwelled through shallow sediments before discharging to the stream channel. The results of a two‐source mixing model based on chloride concentrations suggested that the hyporheic zone was very shallow (<5 cm) in Emmons Creek. 4. Vertical profiles showed that nitrate concentration in shallow ground water was about 10–60% of the nitrate concentration of deep ground water. The mean nitrate concentrations of deep and shallow ground water were 2.17 and 0.73 mg NO₃‐N L^?1, respectively. 5. Deep ground water tended to be oxic (6.9 mg O₂ L^?1) but approached anoxia (0.8 mg O₂ L^?1) after passing through shallow, organic carbon‐rich sediments, which suggests that the decline in the nitrate concentrations of upwelling ground water was because of denitrification. 6. Collectively, our results suggest that there is substantial nitrate removal occurring in deep sediments, below the hyporheic zone, in Emmons Creek. Our findings suggest that not accounting for nitrate removal in deep sediments could lead to underestimates of nitrogen processing in streams and catchments.     

Prevalence and characteristics of eae- and stx-positive strains of Escherichia coli from wild birds in the immediate environment of Tokyo Bay

The prevalence and characteristics of eae- and stx-positive Escherichia coli strains in wild birds in the immediate environment of Tokyo Bay, Japan, was examined using cloacal swab samples taken from 447 birds belonging to 62 species. PCR screening showed that the prevalences of stx- and eae-positive strains of Escherichia coli were 5% (23/447) and 25% (113/447), respectively. Four strains of stx(2f)-positive E. coli were isolated from two feral pigeons, an oriental turtle dove and a barn swallow. In contrast, 39 eae-positive E. coli strains were isolated, and most of the strains possessed a subtype of intimin that is classified as a minor group of human intimins, such as intimin upsilon, kappa, and mu. Moreover, these strains did not possess any of the other pathogenic genes tested, such as stxs, ehxA, bfp, or irp. Thus, wild birds were considered to be a reservoir of atypical enteropathogenic E. coli.     

Spectral evidence for the formation of active intermediates from RuCl3 and RuCl2(PPh3)3 with N-methylmorpholine N-oxide (NMO) and phenyliodosoacetate (PIA) as mild oxidants

Electronic, EPR and IR spectral evidence are given for the formation of the following active species: (1) ruthenium(VIII) in ruthenium(III)-PIA system, (2) ruthenium(V) oxo species in ruthenium(III)-N- oxide system, and (3) ruthenium(II)-phosphine oxide complex in ruthenium(II) N-oxide system. Cyclic voltammetric studies also suggest the formation of Ru(V) in ruthenium(III)-N-oxide system.     

长江口外低氧区及其邻近海域表层沉积物反硝化微生物多样性和分布特征

[目的]微生物参与的反硝化是河口区氮损失的主要途径.[方法]本研究采用Illumina MiSeq测序方法,研究了长江口外低氧区及其邻近海域表层沉积物中nirS型和nirK型反硝化微生物群落的多样性和分布特征.[结果]样品共检测到346个nirS Operational Taxonomic Units和267个nirK...     

Butyrylcholinesterase is present in the human epidermis and is regulated by H2O2: more evidence for oxidative stress in vitiligo

The human epidermis holds the capacity for autocrine cholinergic signal transduction, but the presence of butyrylcholinesterase (BchE) has not been shown so far. Our results demonstrate that this compartment transcribes a functional BchE. Its activity is even higher compared to acetylcholinesterase (AchE). Moreover, we show that BchE is subject to regulation by H(2)O(2) in a concentration-dependent manner as it was recently described for AchE. Epidermal BchE protein expression and enzyme activities are severely affected by H(2)O(2) in vitiligo as previously demonstrated for AchE. Removal/reduction of H(2)O(2) by a pseudocatalase PC-KUS yields normal/increased protein expression and activities. H(2)O(2)-mediated oxidation of methionine residues in BchE was confirmed by FT-Raman spectroscopy. Computer simulation supported major alteration of the enzyme active site and its tetramerisation domain suggesting deactivation of the enzyme due to H(2)O(2)-mediated oxidation. Based on our results we conclude that H(2)O(2) is a major player in the regulation of the cholinergic signal via both AchE and BchE and this signal is severely affected in the epidermis of patients with active vitiligo.     

Pollen in the guts of Permian insects: first evidence of pollinivory and its evolutionary significance

Uniquely preserved pollen was extracted from intestines of fossil insects from the Lower Permian of the Urals. A species of Hypoperlidae, an extinct family ancestral to bark-lice, bugs and plant-hoppers, and two species of Grylloblatida, a predominantly Permian group with a few extant representatives related to stoneflies, contain protosaccate taeniate grains of several pollen genera well known as dispersed microfossils and occasionally found in sporangia of conifers, peltasperms and glossopterids. This is so far the earliest direct evidence of pollinivory, a major factor of plant-insect coevolution. The partly digested pollen grains reveal infratectal reticulum and other structural details of evolutionary significance. It is suggested that the peculiar taeniate pollen of worldwide distribution in the Permian might simultaneously evolve in several groups of Paleozoic seed plants in relation to pollinivory that, by altering the rnicropyle load and thereby the pollen/ovule ratio, could also affect ovuliferous structures. Thus pollinivory might impel rapid diversification of gymnosperms in the Permian. The pollinivorous Hypoperlidae, which have evolved in the direction of ovulivory, might initiate insect pollination in the process.