Comparative study of using different materials as bacterial carriers to treat hydrogen sulfide

The use of support media for the immobilization of microorganisms is widely known to provide a surface for microbial growth and protect the microorganisms from inhibitory compounds. In this study, molecular sieve, granular porous carbon, and ferric oxide desulfurizer, immobilized with autotrophic bacteria capable of oxidizing ferrous iron to ferric iron, were developed to treat hydrogen sulfide (H₂S). Their corresponding bioreactors were referred to as BMS, BPC, and BFO, respectively. H₂S loading, gas retention time, hydrogen ion, and aluminous, ferric, and ferrous iron concentrations of recycling effluents were evaluated. Thermogravimetric analysis, Brauner-Emmett-Teller method, and scanning electron microscopy were used to characterize packing materials. Results showed that the elimination capacity was in the order of BFO > BPC > BMS. This study suggested that the material characteristics progressively influenced the deodorization capacities of bioreactors. H₂S was oxidized into elemental sulfur and oxidized sulfur species, according to differences of carriers. Furthermore, this study revealed the potential application of simultaneously treating of H₂S under extremely acidic conditions.     

植物管状分子发育中的细胞凋亡

细胞凋亡在植物发育过程和防御机制中发挥着重要作用.植物细胞凋亡具有染色质固缩和边缘化、DNA片断化、核的降解、质膜内缩、大量囊泡的出现、细胞壁的修饰等特征,是由相关的基因、蛋白酶以及细胞色素C介导和调控的.本文根据国内外的研究报道,对两种管状分子(导管、筛管)发育过程中细胞凋亡的形态学变化以及机制进行分析,为进一步探讨细胞凋亡的途径和机制提供参考.     

分级分筛式异位重金属污染土壤淋洗技术

本研究采用去离子水作淋洗剂,开发一种分级分筛式异位重金属污染土壤淋洗技术,研究显示,土壤中粒径大于25μm颗粒占比接近80%,重金属Pb、Cu、Ni、Cd和Cr含量分别为125.85 mg/kg、85.93 mg/kg、63.29 mg/kg、1.31 mg/kg和108.39 mg/kg,基本符合土壤环境质量二级标准,可用于农田回用土;土壤中粒径小于25μm颗粒占比低于20%,其对应重金属含量超出土壤环境质量三级标准,可用作制砖原料。     

远端血管通路导管治疗急性脑梗死对血清Adropin蛋白、载脂蛋白A1的影响

摘要 目的：探讨远端血管通路导管治疗急性脑梗死对血清Adropin蛋白、载脂蛋白A1（ApoA1）的影响。方法：将2018年6月到2021年4月选择在本院急诊的急性脑梗死患者84例作为研究对象,根据随机信封1:1抽签原则把患者分为导管组与支架组,各42例。支架组给予支架溶栓治疗,导管组给予远端血管通路导管治疗,比较两组手术相关指标、mTICI分级情况、脑血液流变学变化以及血清Adropin、ApoA1含量等指标。结果：导管组的导引导管到位时间、血管获得再通时间均较支架组少（P<0.05）;导管组治疗后1个月的血管灌注改良脑梗死溶栓试验（mTICI）分级优于支架组（P<0.05）;两组颅脑椎动脉与基底动脉血流速度治疗前均无差异（P>0.05）,治疗后两组的颅脑椎动脉与基底动脉血流速度高于治疗前（P<0.05）,导管组较支架组高（P<0.05）;两组血清Adropin、ApoA1含量治疗前对比无差异（P>0.05）,治疗后两组的血清Adropin、ApoA1含量较治疗前高（P<0.05）,导管组较支架组高（P<0.05）。结论：远端血管通路导管治疗急性脑梗死可加快手术操作改善患者的血管灌注分级情况,促进血清Adropin、ApoA1的释放,有利于患者脑动脉血流速度的恢复。     

High-performance molecular sieve chromatography of proteins on agarose columns: the relation between concentration and porosity of the gel

Curves showing the relation between log (molecular weight) and distribution coefficient are presented for proteins subjected to molecular sieve chromatography on crosslinked and non-crosslinked agarose gels of different concentrations. These curves, which facilitate selection of the gel concentration that gives optimal resolution in any particular separation problem, show that the exclusion limit of 5, 9, 12, and 20% agarose gels correspond to protein with molecular weights above 1,000,000, 600,000, 450,000, and 280,000, respectively. Plate numbers have been determined for columns of 20% agarose at different flow rates and bead sizes. Separations of model proteins by high-performance molecular sieve chromatography on agarose beads are shown.     

Electron-Microscopic Evidence of the Vacuolar Nature of Phloem Exudate

We performed electron-microscopic examination of structural diurnal changes in the lumen of sieve tubes and the vacuolar system of corresponding companion cells and changes induced by the experimental blockage of assimilate export from the leaf by its cold-girdling. For these investigations, Cucurbita pepo L. and Helianthus annuus L. plants were used, that is, plant species from groups of symplastic and apoplastic plants, which differ in the type of companion cells and a mode of phloem terminal loading. The examinations showed the complete identity of changes in the electron texture of the sieve-tube lumens and companion-cell vacuoles in both plant species in the course of a day, when the level of assimilates changed, or after export blockage. Similar changes in the structure of the vacuolar labyrinths were stated in the companion cells under normal conditions and after cold-girdling, as related to the rate of sieve-tube loading with the vacuolar exudate. Vacuolar expansion and starch accumulation developing in response to changes in the assimilate level in the evening and after cold blockage of the assimilate export occurred in different types of cells, as dependent on their position in the symplast domains. However, the rate of the process similarly depended on the balance between assimilate synthesis and export. Synchronous changes in the texture of the sieve-tube lumen and companion-cell vacuoles were observed within each complex, but asynchronous changes occurred in different complexes. We suggested this phenomenon for recognizing the particular complexes, when they are grouped in a bundle. We observed no signs of cytoplasm or protein synthetic machinery in the sieve tubes. We concluded that the sieve-tube lumen and vacuoles of companion cells are common in nature. Similar electron texture of the images of the companion-cell vacuolar labyrinth and tube lumens, their connection through the lateral sieve fields, morphological modifications of the companion-cell vacuolar system as dependent on the activity of sieve tube loading—all of these facts imply the continuity of these transport compartments and fluxes in them and the similarity in the composition of the exudates from companion-cell vacuoles and phloem tubes.     

Solute concentrations of the phloem and parenchyma cells present in squash callus

Abstract. Glutaraldehyde fixation was used to determine the solute concentrations in the various cell types present in tissue cultures of squash ( Cucurbita pepo ). Small pieces of callus were plasmolyzed in a graded series of mannitol solutions and fixed in 20 kg m⁻³ glutaraldehyde adjusted to be isosmotic with the particular plasmolysing solution. The callus samples were further processed using standard electron microscopy techniques. Using this procedure, mature sieve elements that form in squash callus have an osmotic potentional of -2.4MPa. The osmotic potential of the callus sieve elements was comparable to values reported for the sieve tube members of the phloem in intact plants. This ability of callus sieve elements to develop high internal hydrostatic pressures demonstrates that they are capable of phloem loading. However, the osmotic potentials of the surrounding parenchymatous cells and companion cells were only –1.15 and –1.5 MPa, respectively. In contrast to the companion cells of the phloem in intact plant tissues, the osmotic potential of the callus companion cells indicated that they were not directly involved in phloem loading. Several immature sieve elements containing distinct nuclei and vacuoles were observed in the callus granules. These immature sieve elements were plasmolyzed in weaker mannitol solutions (below 0.6kmol m⁻³) than the enucleate sieve elements (1.01 kmol m⁻³ mannitol). The low solute concentrations in immature sieve elements indicated that the ability to load sugars occurs concomitantly with the maturation of the sieve element protoplast.     

Selecting cost effective and policy-relevant biological indicators for European monitoring of soil biodiversity and ecosystem function

Soils provide many ecosystem services that are ultimately dependent on the local diversity and belowground abundance of organisms. Soil biodiversity is affected negatively by many threats and there is a perceived policy requirement for the effective biological monitoring of soils at the European level. The aim of this study was to evaluate and recommend policy relevant, cost-effective soil biological indicators for biodiversity and ecosystem function across Europe. A total of 18 potential indicators were selected using a logical-sieve based approach. This paper considers the use of indicators from the ‘top down’ (i.e. concerned with the process of indicator selection), rather than from the ‘bottom up’ detail of how individual indicators perform at specific sites and with specific treatments. The indicators assessed a range of microbial, faunal and functional attributes, newer nucleic acids based techniques, morphological approaches and process based measurements. They were tested at 6 European experimental sites already in operation and chosen according to land-use, climatic zone and differences in land management intensity. These were 4 arable sites, one each in Atlantic, Continental, Mediterranean and Pannonian climate zones, and 2 grassland sites, one each in Atlantic and Continental zones. At each site we sampled three replicated plots of contrasting management intensity and, while the treatments varied from site to site, their disturbance effects were quantified in terms of land use intensity. The field sampling and laboratory analysis were standardised through a combination of ISO protocols, or standard operating procedures if the former were not available. Sites were sampled twice, in autumn 2012 and spring or autumn 2013, with relative costs of the different indicators being determined each time. A breakdown of the cost effectiveness of the indicators showed the expected trade-off between effort required in the field and effort required in the laboratory. All the indicators were able to differentiate between the sites but, as no single indicator was sensitive to all the differences in land use intensity, we suggest that an indicator programme should be based upon a suite of different indicators. For monitoring under the European climatic zones and land uses of this study, indicators for ecosystem functions related to the services of water regulation, C-sequestration and nutrient provision would include a minimum suite of: earthworms; functional genes; and bait lamina. For effective monitoring of biodiversity all taxonomic groups would need to be addressed.     

Ultrastructure of sieve element penetration by aphid stylets during electrical recording

The probing activities of Brevicoryne brassicae (L.) on a host plant Brassica oleracea (L.) were electronically monitored using a direct current (DC) device. Two electrical penetration graphs are described, including a pattern, D+E, at two different potential levels; the normal level of pattern, C, D+E(c), and the potential drop level, D+E(pd). Stylets were amputated during these patterns, sap exudation from the stumps was scored, and the penetrated leaf area with the remnants of the stylets were processed for EM. Sap was not produced from stylets cut during D+E(c). About 70% of stylets cut during the D+E(pd) pattern produced sap and in micrographs, stylet tips had pierced the sieve element plasmalemma and were found inside the cell lumen. This supports the earlier hypothesis that the D+E(pd) pattern is related to intracellular sieve element penetration. The relation of D+E(c) and D+E(pd) with ingestion is discussed.

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Résumé Les pénétrations par Brevicoryne brassicae de la plante-hôte Brassica oleracea étaient enregistrées électriquement au moyen d'un montage au courant continu. Deux signeaux sont décrits avec l'onde D+E à deux niveaux de potentiel électrique: le niveau normal de l'onde C, D+E(c), et un niveau bas après une chute de potentiel, D+E(pd). Au cours de ces deux ondes les stylets étaient amputés, on a pu observer le jaillisement de sève hors du moignon; on a ensuite préparé une partie de la feuille avec les restes des stylets pour le microscope électronique. Au cours de l'onde D+E(c) on observait aucune production de sève. Environ 70% des stylets amputés pendant l'onde D+E(pd) produisaient de la sève et dans deux de ces cas, dont les signeaux sont décrits, les pointes des stylets se trouvaient dans une cellule des vaisseaux conducteurs en ayant pénétrés le plasmalemme. Ces résultats confirment l'hypothèse antérieure, selon laquelle l'onde D+E(pd) est liée à une pénétration intracellulaire d'un vaisseau conducteur. La relation de l'onde D+E(c) et D+E(pd) avec l'ingestion par l'aphide est discutée.