Chaperon solvent plug design in size-exclusion chromatography protein refolding process

Although the chaperon solvent plug was reported as a strategy to reduce aggregation before the column inlet in SEC (size-exclusion chromatography) protein refolding process, the appropriate position at which sample injected and the volume of the chaperon solvent plug have not been elucidated. Therefore, the detail of chaperon solvent plug design was investigated in this work. Our results indicated that, to ensure good performances in the SEC refolding process, the appropriate front and tail volumes of chaperon solvent plug should be slightly larger than the optimal values, which depend on the flow dispersion from the injector to the column inlet. However, with the front volume more than the optimum, it could have an adverse effect on activity recovery but not the mass recovery, while no effect at all if the tail volume exceeded the optimum. Furthermore, it might be economical to replace the eluent (refolding buffer) after the tail of chaperon solvent plug with a cheaper one.     

塞来昔布联合氟尿嘧啶对胰腺癌细胞株SW1990生长抑制作用及其机制研究

目的:研究选择性环氧化酶-2(COX-2)抑制剂塞来昔布联合氟尿嘧啶对胰腺癌细胞株SW1990生长的抑制作用,并对其机制进行初步探讨.方法:实验分为对照组、氟尿嘧啶组、塞来昔布组及两药联合组,将不同浓度的药物分剐作用于胰腺癌细胞株SW1990,MTT法检测各组细胞的生长抑制率,并探索产生最佳细胞生长抑制作用的药物浓度.流式细胞仪检测不同药物作用对肿瘤细胞周期的影响.RT-PCR检测各组细胞Survivin的表达情况.结果:MTT法显示氟尿嘧啶、塞来昔布均能抑制SW1990的生长,且细胞的存活率都随药物浓度的增加而降低.两药联合组对细胞生长的抑制作用更明显.流式细胞仪检测结果显示塞来昔布组、氟尿嘧啶组及两药联合组细胞较对照组G0/G1期细胞比例明显增加,S期和G2/M期细胞比例明显减少.RT-PCR结果显示氟尿嘧啶组、塞来昔布组、联合组都可下调Survivin的表达,以联合组最为明显.结论:塞来昔布联合氟尿嘧啶对胰腺癌SW1990细胞的生长具有抑制作用,其机制可能与下调Survivin的表达从而诱导细胞的凋亡和细胞周期的停滞有关.     

The removal of nutrients from non-point source wastewater by a hybrid bioreactor

The aim of this project was to establish an economical and environmentally benign biotechnology for removing nutrients from non-point source wastewater. The proposal involves a hybrid bioreactor comprised of sequential anaerobic, anoxic and aerobic (A²/O) processes and an eco-ditch being constructed and applied in a suburban area, Kunming, south-western China, where wastewater was discharged from an industrial park and suburban communities. The results show that the hybrid bioreactor fosters heterotrophic and autotrophic microorganisms. When the hydraulic load is 200 m³ per day with the running mode in 12 h cycles, the removal efficiencies of the nutrients were 81% for TP, 74% for TDP, 82% for TN, 79% for NO₃-N and 86% for NH₄-N. The improved bacterial community structure and bacterial habitats further implied enhanced water quality and indicates that the easily-deployed, affordable and environmentally-friendly hybrid bioreactor is a promising bio-measure for removing high loadings of nutrients from non-point source wastewater.     

Preliminary studies on virus and spirochete accumulation in the cement plug of ixodid ticks

We provide evidence that tick-borne encephalitis virus and Borrelia burgdorferi s.l. are accumulated in the cement plug in the host skin within the first few hours after tick attachment. Extirpation of the tick without the cement plug, even very soon after the attachment, did not prevent the transmission by Ixodes ricinus, Ixodes persulcatus or Dermacentor reticulatus to mice. This was within 1 hour in the case of the TBE virus and after 20–22 h of attachment, in the case of Borrelia and I. persulcatus. The epidemiological significance of these findings is discussed.     

Seed development and function inArtabotrys hexapetalus (Annonaceae)

Until now seeds ofAnnonaceae were characterized as mesotestal only. The seed ofArtabotrys hexapetalus, however, is meso- and endotestal. An outer mechanical layer which surrounds the seed as a lignified fibrous tissue is derived from the mesotesta. A complex inner mechanical layer develops from a partially multi-layered endotesta built up by crystal-containing stone cells. The multi-layered endotesta forms a prominent seed plug in the micropylar region which is prolonged along both sides of the perichalaza as inner walls. The endotesta is one-layered on the sides of the seed and participates in rumination. In addition the endotesta may serve for deposition of end-products of metabolism. The complex growing process of the perichalaza and its surrounding tissues is described in detail. The perichalazal pad of tanniferous cells forms an U-shaped septum, in conjunction with the endotesta, dividing the seed into two chambers. During seed development it functions as transmitter of nutrients from the outer chamber filled with starch grains to the nucellus, endosperm and embryo contained in the inner one. During germination this pad probably serves for the uptake of water. — At the initial phases of germination the seed dehisces into two valves along the raphal and antiraphal side. Later on an additional parenchymatous operculum covering the seed apex disintegrates and the endotestal plug fixed by its two prolongations splits along a preformed fracture line into two parts to release the seedling. Rudiments of an aril are recognizable in young seeds only. — The data obtained fromArtabotrys hexapetalus are discussed and compared with published information on seeds in other annonaceous taxa. For systematic considerations the necessity to define the origin of the annonaceous seed plug from one or the other integument is emphasized as it may prove to be an important differential character withinAnnonaceae.     

Nutrient salts and the toxicity of black-layer induced by cyanobacteria and Desulfovibrio desulfuricans to Agrostis palustris

Cyanobacteria and Desulfovibrio desulfuricans can interact to form a subsurface black-layer in high-sand content golf greens that impairs internal water drainage and results in the decline of the Agrostis palustris turfgrass on the green. Research was initiated to evaluate the effect of mineral salts (sulfur, iron, lime) and fructose (a soluble carbohydrate) added to a balanced nutrient salts control solution on the development and toxicity of black-layer to the growth of A. palustris. The various nutrient salts combinations were applied to single isolates of cyanobacteria and D. desulfuricans in nonblack-layered sand, and to the combination of cyanobacteria and D. desulfuricans (necessary for black-layer development) in black- layered sand. Dry weights of A. palustris treated with the salts control decreased with individual isolates of cyanobacteria and more so in the blackened sand produced by the combinations of cyanobacteria and D. desulfuricans. The addition of sulfur to the salts control increased dry weights of A. palustris growing with single isolates of cyanobacteria and in the sand blackened by the combinations of cyanobacteria and D. desulfuricans compared with the salts control; dry weight decreased in response sulfur only in nonblackened sand with D. desulfuricans alone. The addition of iron to the salts control produced the greatest increase in dry weight relative to the salts control among all single and combined microorganisms, except for D. desulfuricans. The addition of lime or fructose to the salts control decreased dry weight among plants growing in the no-organism control, with D. desulfovibrio alone, and with individual isolates of cyanobacteria relative to the salts control. Dry weights in response to lime and fructose in sand blackened by the combination of cyanobacteria and D. desulfuricans remained unchanged or decreased relative to the salts control. Growing roots of A. palustris cleared the blackening in sand and showed gold-colored cortical cells with blackened cell walls and vascular cylinders. The observations are discussed relative to the role of the various salts on the toxicity of D. desulfuricans to A. palustris in black-layered and nonblack-layer sand.     

Ditches as species‐rich secondary habitats and refuge for meadow species in agricultural marsh grasslands

Questions

Can drainage ditches in agricultural marsh grassland provide a suitable habitat for the persistence of fen meadow species? How does the ditch margin vegetation develop as a function of regular dredging? Is ornithologically oriented management also beneficial for plant biodiversity?

Location

Riparian marshes, Eider‐Treene‐Sorge lowland, Schleswig‐Holstein, Germany.

Methods

We performed vegetation surveys of drainage ditches along with their water body, slope and margin structures annually for 3 years. The data were analysed with respect to date and means of ditch dredging. In addition, we recorded vegetation of the surrounding agricultural grassland, measured nutrient status of the soil and the water body and sampled seed bank of the ditch slopes. We used ANOVA and multivariate methods to describe the development of the ditch vegetation and the persistence of target meadow species.

Results

Vegetation re‐development of ditch margins proceeds quite rapidly after disturbance from dredging. Dominance of mudbank species was observed only in the first year, followed by an increase of reed species and reduction of phytodiversity. Target species of wet meadow communities reach highest abundance in the second and third year and build a significant seed bank before being suppressed by reeds.

Conclusions

In heavily eutrophicated, intensively used marsh grassland, regularly disturbed ditch margins are important secondary habitats for pioneer and subdominant wetland species, which have nearly disappeared in a larger area. Current management cycles of ditch dredging every 3–4 years comply with the successional development, allowing the mudbank and wet meadow species to persist in the vegetation and seed bank. In contrast to the frequency, the form of dredging (ditch profile), which is crucial for bird protection, plays a minor role for plants. We recommend moderate disturbance (mowing of ditch margins) to suppress strong competitors in the years between dredging for additional support to target plant species.     

Empirical Fuel Consumption and CO2 Emissions of Plug‐In Hybrid Electric Vehicles

Plug‐in hybrid electric vehicles (PHEVs) combine electric and conventional propulsion. Official fuel consumption values of PHEVs are based on standardized driving cycles, which show a growing discrepancy with real‐world fuel consumption. However, no comprehensive empirical results on PHEV fuel consumption are available, and the discrepancy between driving cycle and empirical fuel consumption has been conjectured to be large for PHEV. Here, we analyze real‐world fuel consumption data from 2,005 individual PHEVs of five PHEV models and observe large variations in individual fuel consumption with deviation from test‐cycle values in the range of 2% to 120% for PHEV model averages. Deviations are larger for short‐ranged PHEVs. Among others, range and vehicle power are influencing factors for PHEV model fuel consumption with average direct carbon dioxide (CO₂) emissions decreasing by 2% to 3% per additional kilometer (km) of electric range. Additional simulations show that PHEVs recharged from renewable electricity can noteworthily reduce well‐to‐wheel CO₂ emissions of passenger cars, but electric ranges should not exceed 200 to 300 km since battery production is CO₂‐intense. Our findings indicate that regulations should (1) be based on real‐world fuel consumption measurements for PHEV, (2) take into account charging behavior and annual mileages, and (3) incentivize long‐ranged PHEV.     

Retention of Ejaculate by Drosophila melanogaster Females Requires the Male-Derived Mating Plug Protein PEBme

Within the mated reproductive tracts of females of many taxa, seminal fluid proteins (SFPs) coagulate into a structure known as the mating plug (MP). MPs have diverse roles, including preventing female remating, altering female receptivity postmating, and being necessary for mated females to successfully store sperm. The Drosophila melanogaster MP, which is maintained in the mated female for several hours postmating, is comprised of a posterior MP (PMP) that forms quickly after mating begins and an anterior MP (AMP) that forms later. The PMP is composed of seminal proteins from the ejaculatory bulb (EB) of the male reproductive tract. To examine the role of the PMP protein PEBme in D. melanogaster reproduction, we identified an EB GAL4 driver and used it to target PEBme for RNA interference (RNAi) knockdown. PEBme knockdown in males compromised PMP coagulation in their mates and resulted in a significant reduction in female fertility, adversely affecting postmating uterine conformation, sperm storage, mating refractoriness, egg laying, and progeny generation. These defects resulted from the inability of females to retain the ejaculate in their reproductive tracts after mating. The uncoagulated MP impaired uncoupling by the knockdown male, and when he ultimately uncoupled, the ejaculate was often pulled out of the female. Thus, PEBme and MP coagulation are required for optimal fertility in D. melanogaster. Given the importance of the PMP for fertility, we identified additional MP proteins by mass spectrometry and found fertility functions for two of them. Our results highlight the importance of the MP and the proteins that comprise it in reproduction and suggest that in Drosophila the PMP is required to retain the ejaculate within the female reproductive tract, ensuring the storage of sperm by mated females.     

Effect of the mating plug on female chemical attractiveness and mating acceptance in a scorpion

After mating, females may experience a decline in sexual receptivity and attractiveness that may be associated with changes in the production and emission of sex pheromones. In some cases, these changes are produced by chemical substances or structures (e.g., mating plugs) produced by males as a strategy to avoid or reduce sperm competition. In scorpions, sex pheromones may be involved in finding potential mates and starting courtship. Here, we tested the hypothesis that the males of Urophonius brachycentrus, a species that produces a mating plug, use chemical communication (sex pheromones) to detect, localize, and discriminate females according to their mating status (virgin or inseminated), aided by chemical signaling. We also explored the effect of extracting of the mating plug on chemical communication and mating acceptance. We used Y‐maze olfactometers with different stimuli to analyze male choice and exploration time. To evaluate mating acceptance, we measured the attractiveness and receptivity of females of different mating status. We found that chemical communication occurs through volatile pheromones, but not contact pheromones. Males equally preferred sites with virgin or inseminated females with removed mating plug. In turn, females with these mating statuses were more attractive and receptive for males than inseminated females. This study suggests that the mating plug significantly affects female chemical attractiveness with an effect on volatile pheromones and decreasing sexual mating acceptance of females. The decline in the female's sexual receptivity is a complex process that may respond to several non‐exclusive mechanisms imposed by males and strategically modulated by females.