Massenentwicklungen von Algen und Wasserlinsen in der Talsperre Bleiloch (Thüringen) — gegenwärtige Situation,Ursachenanalyse und erste Ergebnisse zu deren Verringerung Algal Blooms and Duckweed Covers in the Bleiloch Reservoir (Thuringia) — Actually Situation,Causal Analysis and First Results of its Overcome

The effects of a decreased sewage release from a cellulose mill on the hypertrophic Bleiloch reservoir were studied. The waste water treatment reduced the concentration of yellow substances in the reservoir and resulted in a more light-coloured waterbody. It is estimated that the changes in the light attenuation in the Bleiloch reservoir after 1989 can be described as eutrophication. Selected physical, chemical, and biological parameters from 1994 show the effect of changes. Three large pelagic enclosures (diameter 10 m, length 20 m) were installed in the reservoir to assess effects of artifical mixing on phytoplankton biomass and composition. Two circulation techniques have been used in the enclosures (relase of compressed air at the bottom of the enclosure and mechanical mixing, where water was pumped from the surface downward). The investigation demonstrate that the magnitude of seasonal peaks of chlorophyll were depressed in the mixed enclosures during circulation. The results were discussed in comparison with a reference enclosure without mixing and the waterbody of the reservoir. Cryptophytes and other flagellates achieved dominance during mixing in the “air”-enclosure, while diatoms were the most abundant species in the „pump”︁-enclosure. The development of filamentous cyanobacteria, which are significant indicators of eutrophication, was disturbed in the enclosures. They were outcompeted by cryptophytes, movable chlorophytes and diatoms. Both mechanical pump and compressed air can be used to control excessive algal growth. Further studies on the dynamics of phytoplankton to artifical mixing are suggested. The results of further studies should design an in situ experiment in the reservoir to reduce algal growth by light limitation. Further on a dense duckweed cover spreads over the surface of the Bleiloch reservoir, which influences the light regime in the waterbody. Therefore factors influencing the duckweed growth were analysed. Special attention was focused on the influence of the pH, consequences of the mixing in the waterbody and the role of resting stages.     

Status and distribution of jaguarundi in Texas and Northeastern México: Making the case for extirpation and initiation of recovery in the United States

The jaguarundi (Puma yagouaroundi) is a small felid with a historical range from central Argentina through southern Texas. Information on the current distribution of this reclusive species is needed to inform recovery strategies in the United States where its last record was in 1986 in Texas. From 2003 to 2021, we conducted camera‐trap surveys across southern Texas and northern Tamaulipas, México to survey for medium‐sized wild cats (i.e., ocelots [Leopardus pardalis], bobcats [Lynx rufus], and jaguarundi). After 350,366 trap nights at 685 camera sites, we did not detect jaguarundis at 16 properties or along 2 highways (1050 km²) in Texas. However, we recorded 126 jaguarundi photographic detections in 15,784 trap nights on 2 properties (125.3 km²) in the northern Sierra of Tamaulipas, Tamaulipas, México. On these properties, latency to detection was 72 trap nights, with a 0.05 probability of detection per day and 0.73 photographic event rate every 100 trap nights. Due to a lack of confirmed class I sightings (e.g., specimen, photograph) in the 18 years of this study, and no other class I observations since 1986 in the United States, we conclude that the jaguarundi is likely extirpated from the United States. Based on survey effort and results from México, we would have expected to detect jaguarundis over the course of the study if still extant in Texas. We recommend that state and federal agencies consider jaguarundis as extirpated from the United States and initiate recovery actions as mandated in the federal jaguarundi recovery plan. These recovery actions include identification of suitable habitat in Texas, identification of robust populations in México, and re‐introduction of the jaguarundi to Texas.     

Assessment of diet choice by the yellow fever mosquito Aedes aegypti

To investigate feeding‐related decisions in Aedes aegypti (L.), adults are presented with simple diets of paired gustatory stimuli conveying information concerning energy content, nutrient richness, osmotic balance and food toxicity in a two‐diet matrix assay. Assessment of mosquito gut contents indicates that both sexes accept single sugar diets in a dose‐dependent manner. When presented with a choice between two different yet equimolar sugar solutions, more individuals of both sexes accept the disaccharides, sucrose and trehalose, than the monosacharrides, fructose and glucose. The combination of pyranose and furanose sugars in solution, either physically associated (as in sucrose) or present as monomers (as glucose and fructose), is accepted over solutions containing a single sugar moiety. Using the two‐diet matrix assay, mosquito diet‐choice is also tested between two equimolar sucrose ‘driver’ solutions in which one is presented with various concentrations of another potential feeding cue ‘test’ compound (i.e. each of the 20 naturally‐occurring amino acids, sodium chloride, quinine or caffeine). Diet‐choice between the ‘driver’ sucrose‐only solution and the solution of the ‘driver’ sucrose containing a ‘test’ amino acid is influenced by sex, amino acid concentration and sucrose concentration. There is also an example of synergism between the diet components, leucine and sucrose. Mosquitoes demonstrate a dose‐dependent acceptance of sucrose‐only diets over sodium chloride‐containing sucrose when presented together. Interestingly, the sucrose‐only diet is accepted by more mosquitoes than all concentrations of the saline‐containing sucrose diets except those approximately isotonic to mosquito haemolymph, at which concentration mosquitoes show no clear choice between the diets. More individuals of both sexes accept sucrose‐only diets than the diets of caffeine‐containing sucrose in a dose‐dependent manner. Only females, however, respond to quinine‐containing sucrose diets and modulate this behaviour in relation to the energetic reward: more females imbibed quinine‐containing sucrose at the higher sucrose concentration (1 m ). A systematic characterization of diet selection behaviour of A. aegypti is presented for 27 putative feeding cues potentially involved in nectar/honeydew feeding. This study will be used as a basis from which to investigate further the mosquito's assessment of food quality and ultimately host choice.     

Potential Effects of Climate Warming on Fish Habitats in Temperate Zone Lakes with Special Reference to Lake 239 of the Experimental Lakes Area (ELA), North-Western Ontario

We used simple statistics (e.g. mean temperature, degree days, cumulative volume days) to describe present thermal habitats for cool water (yellow perch, Perca flavescens) and cold water (lake trout, Salvelinus namaycush) fish of a small boreal lake. We then modelled changes in the vertical and temporal extent of these habitats under various scenarios of climatic change that included increases in air temperature of 2°C, 4°C, and 9°C, and positive and negative deviations from present levels of 10% in solar radiation and relative humidity, and 20% in wind speed and the lake water extinction coefficient. Model simulations indicated pronounced changes in the temporal and vertical availability of fish thermal niche space. These changes were mainly driven by the large increases in mean mixed layer temperatures that corresponded to 85% of the increases in air temperature, but, in particular, changes in light attenuation also resulted in some non-linear, unexpected effects in the distribution and seasonal availability of thermal niche space. As expected, classical lake trout thermal habitat (5–15°C) was progressively reduced and almost disappeared in littoral areas in spring and early summer. Perch thermal niche space expanded for air temperature increases of up to 4°C, but largely disappeared for the 9°C increase. We discuss changes in thermal habitat with regard to the life history of lake trout and yellow perch, and include other determinants of fish habitat to evaluate the potential of these species for long-term ecological success under climatic warming.     

A two-dimensional proteome map of maize endosperm

We have established a proteome reference map for maize (Zea mays L.) endosperm by means of two-dimensional gel electrophoresis and protein identification with LC-MS/MS analysis. This investigation focussed on proteins in major spots in a 4-7 pI range and 10-100 kDa M(r) range. Among the 632 protein spots processed, 496 were identified by matching against the NCBInr and ZMtuc-tus databases (using the SEQUEST software). Forty-two per cent of the proteins were identified against maize sequences, 23% against rice sequences and 21% against Arabidopsis sequences. Identified proteins were not only cytoplasmic but also nuclear, mitochondrial or amyloplastic. Metabolic processes, protein destination, protein synthesis, cell rescue, defense, cell death and ageing are the most abundant functional categories, comprising almost half of the 632 proteins analyzed in our study. This proteome map constitutes a powerful tool for physiological studies and is the first step for investigating the maize endosperm development.     

红花黄色素对新生鼠缺氧后一氧化氮合酶表达的影响

目的:观察红花黄色素对缺氧后脑内诱生型一氧化氮合酶(iNOS)、神经原型一氧化氮合酶(nNOS)及内皮型一氧化氮合酶(eNOS)基因表达的影响,探讨红花黄色素抗缺氧脑损伤的作用.方法:采用SD新生鼠缺氧模型,于缺氧前30 min腹腔注射红花黄色素生药7g/kg,缺氧40 min后复氧48 h,提取脑组织总RNA,应用RT-PCR技术检测三种NOS mRNA的表达量.结果:新生鼠缺氧再复氧48 h,脑内iNOS、nNOS基因表达上升(P＜0.05),预先给予红花黄色素能抑制iNOS、nNOS基因的表达(P＜0.05),但eNOS基因表达不受影响.结论:红花黄色素对缺氧脑损伤的保护作用与NOS基因表达有关.     

Effects of pretreatment with a xanthine oxidase inhibitor on free radical levels during carotid endarterectomy

Objective: Free radicals contribute to the tissue damage caused by ischaemia-reperfusion. The aim of the present study was to investigate whether preoperative antioxidant therapy (allopurinol) affects free radical levels in cerebral venous blood in connection with surgery for carotid artery stenosis.

Materials and methods: Twenty-five patients were randomised into the study. Thirteen were controls and 12 were pretreated with allopurinol the day before surgery. Before, during and after surgery, blood samples were drawn from the ipsilateral jugular vein. Radical levels were measured using the spin trap technique ex vivo using OXANOH as the spin trap. Multivariate statistics were used with Principal Component Analysis and Partial Least Square regression analysis.

Results: Radical levels increased with diabetes, high leukocyte count, high creatinine and a high degree of contralateral stenosis. Radical levels decreased with high age, blood pressure, collateral circulation as well as operation for left-side carotid artery stenosis. After pretreatment with allopurinol, several of the relationships noted in the control group were eliminated, i.e. leukocyte count, side of operation, Betapred pretreatment and collateral circulation.

Conclusions: Radical levels can be determined in connection with surgery for carotid artery stenosis using an ex vivo spin trap method. With preoperative antioxidant therapy the relationships between enhanced radical levels and clinical data, as seen in control subjects, disappeared. This might indicate a beneficial effect of preoperative pretreatment with antioxidants.     

Exploration of the transition state for tertiary structure formation between an RNA helix and a large structured RNA

Docking of the P1 duplex into the pre-folded core of the Tetrahymena group I ribozyme exemplifies the formation of tertiary interactions in the context of a complex, structured RNA. We have applied Phi-analysis to P1 docking, which compares the effects of modifications on the rate constant for docking (k(dock)) with the effects on the docking equilibrium (K(dock)). To accomplish this we used a single molecule fluorescence resonance energy transfer assay that allows direct determination of the rate constants for formation of thermodynamically favorable, as well as unfavorable, states. Modification of the eight groups of the P1 duplex that make tertiary interactions with the core and changes in solution conditions decrease K(dock) up to 500-fold, whereas k(dock) changes by 相似文献   

A mutant heterodimeric myosin with one inactive head generates maximal displacement

Each of the heads of the motor protein myosin II is capable of supporting motion. A previous report showed that double-headed myosin generates twice the displacement of single-headed myosin (Tyska, M.J., D.E. Dupuis, W.H. Guilford, J.B. Patlak, G.S. Waller, K.M. Trybus, D.M. Warshaw, and S. Lowey. 1999. Proc. Natl. Acad. Sci. USA. 96:4402-4407). To determine the role of the second head, we expressed a smooth muscle heterodimeric heavy meromyosin (HMM) with one wild-type head, and the other locked in a weak actin-binding state by introducing a point mutation in switch II (E470A). Homodimeric E470A HMM did not support in vitro motility, and only slowly hydrolyzed MgATP. Optical trap measurements revealed that the heterodimer generated unitary displacements of 10.4 nm, strikingly similar to wild-type HMM (10.2 nm) and approximately twice that of single-headed subfragment-1 (4.4 nm). These data show that a double-headed molecule can achieve a working stroke of approximately 10 nm with only one active head and an inactive weak-binding partner. We propose that the second head optimizes the orientation and/or stabilizes the structure of the motion-generating head, thereby resulting in maximum displacement.