Population dynamics of beech scale (Cryptococcus fagisuga) (Coccina,Pseudococcidae) related to physiological defence reactions of attacked beech trees (Fagus sylvatica)

Summary Changes in the density of beech scale infestation (Cryptococcus fagisuga) of a mature beech stand (Fagus sylvatica) were investigated after gap-cutting in limed and unlimed areas bordering on the gaps and in untreated areas over a 5-year period. Parallelly the concentrations of sucrose, protein amino acids, and procyanidins were examined in the inner and outer bark of non-infested beech trees and beeches infested by beech scale.Irrespective of liming in the areas bordering on the gaps the proportion of beech trees with increasing beech scale infestation was significantly higher, the proportion of beeches with diminishing infestation was significantly lower than in the untreated control areas. Trees with the same infestation tendency occurred in clusters.Physiological defence reactions in the inner and outer bark of the infested beech trees were registrated as an increase in the procyanidin content and a decrease in the protein amino acid content. A change in the outer bark—inner bark—ratio of the infested beech trees showed a transfer of compounds between the inner and outer bark. During the period of observation long-lasting shifts occurred in the pattern of compounds of the bark irrespective of actual infestation intensity.     

EDTA and citric acid mediated phytoextraction of Zn, Cu, Pb and Cd through marigold (Tagetes erecta)

Phytoextraction is an emerging cost-effective solution for remediation of contaminated soils which involves the removal of toxins, especially heavy metals and metalloids, by the roots of the plants with subsequent transport to aerial plant organs. The aim of the present investigation is to study the effects of EDTA and citric acid on accumulation potential of marigold (Tagetes erecta) to Zn, Cu, Pb, and Cd and also to evaluate the impacts of these chelators (EDTA and citric acid) in combination with all the four heavy metals on the growth of marigold. The plants were grown in pots and treated with Zn (7.3 mg l(-1)), Cu (7.5 mg I(-1)), Pb (3.7 mg l(-1)) and Cd (0.2 mg l(-1)) alone and in combination with different doses of EDTA i.e., 10, 20 and 30 mg l(-1). All the three doses of EDTA i.e., 10, 20 and 30 mg l(-1) significantly increased the accumulation of Zn, Cu, Pb and Cd by roots, stems and leaves as compared to control treatments. The 30 mg l(-1) concentration of citric acid showed reduced accumulation of these metals by root, stem and leaves as compared to lower doses i.e., 10 and 20 mg l(-1). Among the four heavy metals, Zn accumulated in the great amount (526.34 mg kg(-1) DW) followed by Cu (443.14 mg kg(-1) DW), Pb (393.16 mg kg(-1) DW) and Cd (333.62 mg kg(-1) DW) in leaves with 30 mg l(-1) EDTA treatment. The highest concentration of EDTA and citric acid (30 mg l(-1)) caused significant reduction in growth of marigold in terms of plant height, fresh weight of plant, total chlorophyll, carbohydrate content and protein content. Thus EDTA and citric acid efficiently increased the phytoextractability of marigold which can be used to remediate the soil contaminated with these metals.     

Alterations of biochemical parameters in malformed Indian rice frogs, Rana limnocharis from Southern Taiwan

The purpose of this study is to investigate the factors that cause malformed frogs in upstream Kaoping river (KP site) and Tungkang river (T site) of Southern Taiwan. In this experiment, the activities of monooxygenase (MO), glutathione-S-transferase (GST), acetylcholinesterase (AchE) as well as the concentration of vitellogenin (Vg) in the liver were measured. Results show that activities of MO, GST and AchE, and Vg levels in normal frogs (male/female) were 0.09 +/- 0.02/0.09+/-0.01 deltaA min(-1) mg(-1) protein, 0.12 +/- 0.04/0.13 +/- 0.04 deltaA min(-1) mg(-1) protein, 6.13 +/- 2.69/6.01 +/- 2.09 U mg(-1) protein and 0.87 +/- 0.42/2.18 +/- 0.50 microg mg(-1) protein, respectively. Activities of MO, GST and AchE, and Vg levels in malformed frogs (male/female) were 0.15 +/- 0.04/0.21 +/- 0.07 deltaA min(-1) mg(-1) protein, 0.27 +/- 0.08/0.30 +/- 0.12 deltaA min(-1) mg(-1) protein, 4.59 +/- 2.71/5.19 +/- 3.74 U mg(-1) protein and 1.46 +/- 0.61/3.15 +/- 0.88 microg mg(-1) protein, respectively in KP site, and were 0.16 +/- 0.69/0.1 +/- 80.07 deltaA min(-1) mg(-1) protein, 0.21 +/- 0.07/0.24 +/- 0.08 deltaA min(-1) mg(-1) protein, 5.13 +/- 4.58/3.94 +/- 1.33 U mg(-1) protein and 2.23 +/- 1.47/4.11 +/- 1.63 microg mg(-1) protein, respectively in T site. These results indicate that male and female malformed frogs in both rivers upstream are found with higher activities. No significant difference in AchE activity was found between normal and malformed frogs in this investigation. It is therefore reasonable to speculate that the organic chemicals released from agricultural activities are presumable the main factors that lead to the malformation of frogs.     

西南水稻白叶枯病菌致病型多样性的垂直分布格局及成因探讨

利用6个含有单抗基因的近等基因系材料为鉴别品种,在水稻的孕穗期采用剪叶接种的方法,测定了西南不同海拔稻区218株水稻白叶枯病菌（Xanthomonas oryzae pv.oryzae）的致病型。结果表明,（1）西南稻区水稻白叶枯病菌致病型具有丰富的多样性,共包含18种,其中9种新致病型为西南地区特有的类型。（2）不同海拔稻区病菌致病型组成存在明显差异,中海拔稻区病菌致病型数量最多,高海拔稻区次之,低海拔稻区最少。低海拔稻区病菌致病型多样性指数、均匀度指数均最低,并且与中海拔和高海拔稻区差异显著。（3）通过分析病菌对抗性基因的克服数量以及鉴别品种病斑长度,表明不同海拔稻区病菌毒力存在明显差异。病菌的毒力与其地理来源的海拔高度呈负相关关系。（4）聚类分析结果显示,以致病型彼此间相似率60%为界,18种致病型可归为4个聚类簇,其中簇Ⅰ毒性最弱,主要集中了高海拔稻区的菌株,簇Ⅳ毒性最强,集中的主要是低海拔菌株。（5）相关性分析表明,病菌致病型多样性特征值与气候类型和寄主品种的多样性呈线性相关关系,气候类型和寄主品种影响病菌致病型的多样性分布,并且寄主品种对病菌的影响程度高于气候类型。就品种的布局而言,低海拔稻区应尽可能使用含有多个抗性基因的聚合品种,而在中、高海拔稻区,应制定好抗性基因轮换的宏观计划,减少低海拔地区向海拔较高的地区稻种的频繁调运,降低水稻白叶枯病的危害。     

复合塘-湿地系统水生植物时空分布对氮磷去除的影响

利用复合生态塘-湿地处理系统水生植物时空格局异质性,研究了水生植物分布对氮、磷去除影响.结果表明,水生植物种类和数量的分布差异导致各单元氮、磷去除呈现不同的周期变化;水生植物主要通过改变硝化/反硝化进程、自身代谢和化学沉降速率影响NH3、NOx-、有机氮和总磷的去除.系统不同单元中氮、磷去除机制差异决定了NH3和总磷主要在曝气养鱼塘(去除率分别为29.5%、30.1%)、鱼塘(16.9%、17.8%)和水生植物塘(24.5%、19.4%)去除;NOx-主要在芦苇湿地(出水<0.4 mg/L)去除;而有机氮则主要在复合兼性塘(32.3%)和鱼塘(28.1%)去除.此外,生态塘出水中水生植物绝大部分被芦苇湿地所截滤,它们的腐败/释放导致湿地中NH3和总磷的表观去除率偏低(分别小于8.5%和11.5%).     

纳米氧化镍颗粒对长牡蛎(Crassostreagigas)抗氧化防御体系的影响

纳米氧化镍(nNiO)作为一种广泛使用的纳米颗粒,其水生毒理效应研究还很有限。为探索n Ni O对海洋贝类的毒性机制,本研究将长牡蛎(Crassostrea gigas)置于不同浓度(0、1、10、100 mg·L~(-1))的n Ni O中暴露96 h,分别测定鳃和消化腺组织的丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,并通过实时荧光定量PCR技术测定了鳃和消化腺中应激蛋白HSP70和AOX基因的表达变化。结果显示:在100 mg·L~(-1)n Ni O处理下,2种组织中MDA含量均显著性升高(P0.01),显示纳米颗粒造成了长牡蛎的脂质过氧化,并可能引起相应的氧化损伤。同时,n Ni O暴露也诱导了长牡蛎抗氧化酶(SOD、CAT和POD)活性的改变。其中,SOD和CAT活性在10 mg·L~(-1)浓度处理组达到最高,而POD活性在1 mg·L~(-1)浓度组即达最高值。在高浓度n Ni O(100 mg·L~(-1))胁迫下,3种抗氧化酶的活性均比低浓度(1和10 mg·L~(-1))处理组降低,表明抗氧化酶的保护作用在较低浓度暴露下更有效;而热激蛋白(hsp70)和交替氧化酶(aox)基因却分别在长牡蛎消化腺和鳃组织中上调表达(P0.01),并表现出一定的组织差异。说明高浓度纳米颗粒暴露中主要是应激蛋白发挥了作用。本文结果为纳米氧化镍对海洋双壳贝类的毒性机制研究及生态风险评估提供了基础数据。     

Diel changes in phytoplankton photosynthetic efficiency in Brackish waters

From 18 to 23 September 1974, investigations on the diel changes in phytoplankton were carried out in the Baltic Sea. Every 4 h, water samples were collected from 2 and 15 m, and PO₄, chlorophyll a, temperature, salinity, pH, phytoplankton composition and phytoplankton light photosynthesis relationship were determined. Continuous measurements of surface irradiance and some estimations of zooplankton were also made. P ^B (photosynthesis per unit chlorophyll a at low light levels of 2·10^-2 cal cm^-2 min^-1) revealed only random variation during the sampling period, i.e., 1.0 to 1.6 mg C (mg chlorophyll a)^-1 h^-1. P _m ^B (Light-saturated photosynthesis per unit of chlorophyll a) displayed pronounced diel fluctuations with the highest value of about 6 mg C (mg chlorophyll a)^-1 h^-1 around noon, and the lowest value of about 2.5 mg C (mg chlorophyll a)^-1 h^-1 during the night, during which latter period the value of P _m ^B was more or less constant. Reasons for the diel fluctuations are discussed, and an equation which describes these fluctuations is proposed. Using this equation, the daily phytoplankton production estimated in incubators by a previously described method can be corrected for the time of day at which samples are collected.     

Nitrogen cycling in microbial mats: rates and patterns of denitrification and nitrogen fixation

Spatial and temporal variations in nitrogen fixation and denitrification rates were examined between July 1991 and September 1992 in the intertidal regions of Tomales Bay (California, USA). Microbial mat communities inhabited exposed mudflat and vegetated marsh surface sediments. Mudflat and marsh sediments exhibited comparable rates of nitrogen fixation. Denitrification rates were higher in marsh sediments. Nitrogen fixation rates were lowest during January at both sites, whereas highest rates occurred during summer and fall. Denitrification rates were highest during fall and winter months in marsh sediments, while rates in mudflat sediments were highest during summer and fall. In mudflat sediments, nitrogen fixation and denitrification rates, integrated over 24 h, ranged from 6 to 79 mg N m^-1 d^-1 and 1 to 10 mg N m^-2 d^-1, respectively. Rates of denitrification represented between 6 and 20% of nitrogen fixation rates during the day, but exceeded or were equivalent to nitrogen fixation rates at night. The highest integrated rates of both nitrogen fixation and denitrification occurred during July, whereas, the highest percent loss occurred during spring when denitrification rates amounted to 20% of nitrogen fixation rates during the day. Over an annual cycle, inputs of fixed N to mudflat communities occurred exclusively during daylight. These results underscore the importance of determining integrated diel rates of both nitrogen fixation and denitrification when constructing N budgets. Using this approach, it was shown that microbial denitrification can represent a significant loss of combined nitrogen from mats on daily as well as monthly time scales.     

Sewage fluxes and seasonal dynamics of physicochemical characteristics of the Bhagirathi-Hooghly River from the lower stretch of River Ganges,India

ABSTRACT

To understand the temporal variations of the physicochemical characteristics of the Bhagirathi-Hooghly River (BHR), three locations representing three districts of West Bengal were selected. The material fluxes from 34 drains during pre-monsoon season was quantified. The analysis of variance (ANOVA) revealed that no significant spatial variations were observed for the physicochemical parameters, whereas seasonal variations were significant. The mean discharge was found to be highest (247.2?×?10³?m³?d^?1) in the midstream drains. Highest mean concentrations of dissolved oxygen (DO) (7.35?mg?L^?1) and nitrate (0.81?mg?L ^?1) were observed during the post-monsoon season followed by the monsoon and pre-monsoon. According to the BIS, WHO and the European standard of water quality (pH, 6.5–8.5; Nitrate, 0–2.5?mg?L^?1;DO, ≥5?mg?L^?1), the results of the respective parameters revealed the BHR system is maintained at high to good water quality, meaning that the BHR system is slightly altered from its pristine environment. The mean concentrations of biological and chemical oxygen demands were found to be high during the monsoon season, revealing that a large quantity of refractory organic matter is transported to the eastern Bay of Bengal from the Ganges.     

Morpho-histological and enzymatic alterations in earthworms Drawida willsi and Lampito mauritii exposed to urea,phosphogypsum and paper mill sludge

The effects of varying concentrations of urea, phosphogypsum and paper mill sludge (PMS) on the morphology, histology, tissue protein content, lipid peroxidation (LPX), activities of lactate dehydrogenase (LDH), acetylcholinesterase (AChE) and catalase in earthworms Drawida willsi and Lampito mauritii have been studied over an exposure period of 24?hr. Integumentary lesions, clitellar swelling and loss of pigmentations were found to be major morpho-pathological changes in the worms. Histology indicated cuticular damage, ruptured epithelium and muscle fibres with accumulation of cellular debris. Lowest tissue protein content (57.02?±?4.02?mg/g tissue) and highest LPX (0.113?±?0.04, 0.137?±?0.08?nmol/mg protein) were noticed in D. willsi at a high concentration of PMS, whereas highest tissue protein content was observed in L. mauritii (115.32?±?7.18?mg/g tissue) with the same treatment. In both the species, LDH activity was minimum at a high concentration of urea (0.172?±?0.02; 0.247?±?0.08?U/mg protein). AChE activity was highest (0.099?±?0.002?U/mg protein) at a high concentration of PMS in D. willsi, whereas catalase activity was the maximum (0.338?±?0.02?U/mg protein) at high concentrations of PMS in L. mauritii. The study indicated that morpho-histological and enzymatic alterations in these earthworms exposed to agrochemicals could be useful biomarkers to evaluate soil toxicity.     

Quantitative relationships among phytoplankton body size classes and production processes in the North Adriatic frontal region

The variation patterns of phytoplankton standing crop and productivity in the North Adriatic frontal region and the relative importance of pico-, nano-, micro-phytoplankton are shown. Data of standing crop (chlorophyll a - Chl a ) and productivity ( 14 C assimilation) and PAR radiation ( w Em m 2 r s m 1 ) were collected during the four oceanographic cruises of the PRISMA II project. Average standing crop and productivity in the study area were 1.41 - 0.42 r mg r m m 3 Chl a and 1.23 - 0.37 r mg r C r m m 3 r h m 1 ; average assimilation number (P/B) was 0.872 - 0.589 r mg r C (mg-Chl a ) m 1 h m 1 and average photosynthetic efficiency (PE) was 0.020 - 0.054 (mg r C(mg-Chl a ) m 1 r h m 1 ) [ w Em m 2 r s m 1 ] m 1 . Phytoplankton biomass and productivity showed significant patterns of variation with the distance from the coast, with increasing depth and decreasing light intensity. The same patterns were shown by the three phytoplankton size classes. The spatio-temporal variations were significantly larger within the microplankton than within the pico- and nano-plankton size classes. Planktonic guilds were dominated by picoplankton, both as standing crop and productivity, in the northern stations (0.539 - 0.21 r mg r m m 3 Chl a and 0.572 - 0.25 r mg r C r m m 3 r h m 1 ) and in those more offshore, while microplankton was more important in the coastal and southern stations (0.727 - 0.58 r mg r m m 3 Chl a and 0.63 - 0.28 r mg r C r m m 3 r h m 1 ). In relative terms, picoplankton accounts for the 53% and 46% of biomass and primary production, while the microplankton account for the 43.6% and 48%. Assimilation number and photosynthetic efficiency did not show spatio-temporal variations but PE was inversely related with PAR radiation for all the size classes. Data suggest that the spatio-temporal patterns observed in this study are affected by the competitive relationships among body size classes in the phytoplankton guilds.     

鱼类镰刀菌的研究Ⅲ：几种药物对鱼类镰刀菌的抑制作用

研究发现制霉素（14．4～16．0mg·L－1）、K制剂（4．0mp·L－1）和孔雀绿（3,0～40mp·L-1）对镰刀菌Fu2和尖F1抑制效果好,而对Fu1-2抑制效果差;优氯净（2．0mg·L－1）能抑制Fu1-2,而不抑制Fu2和尖F1;龙胆紫（1．0mg·L-1）可抑制尖F1,而不抑制Fu2和Fu1-2制霉素对鱼毒性最小,而孔雀绿毒性最大．     

Invasive insect abundance varies across the biogeographic distribution of a native host plant.

Studies of biogeographic variation in species abundances are fundamental to understanding and predicting the impacts of invasive exotic species. We quantified the abundance of the introduced and now invasive biocontrol weevil, Rhinocyllus conicus, on a newly adopted native host plant, Cirsium canescens (Platte thistle), across the plant's distributional range. We used regression and structural equation analyses to examine variation in weevil abundance at 92-108 sites over three years in relation to variation in abiotic and biotic parameters hypothesized to be important in insect or plant dynamics and distribution. We found that R. conicus now occurs throughout the majority of the range of C. canescens, even in the center of the native plant's distribution where its coevolved, targeted weed host (Carduus nutans, musk thistle) is absent. In fact, weevil densities were greater in the center of the native plant's distribution in the Sand Hills formation than in peripheral sand patches closer to areas where the targeted 'exotic thistle is common. None of the macroclimatic variables examined were consistent predictors of the large-scale variation in weevil abundance on C. canescens. In addition to biogeographic position, the only other consistent predictor of weevil densities across sites was the number of flower heads per C. canescens plant. These results exclude the "spillover" hypothesis to explain nontarget feeding on this newly adopted native host species. Instead, the results are consistent with the alternative hypothesis that exotic weevil abundance on C. canescens is related to the local availability of native floral resources. Because C. canescens densities have declined with increases in R. conicus at sites central in the plant's distribution, these results suggest that isolated, peripheral populations of C. canescens are likely to be critical for persistence of Platte thistle. More generally, this study suggests that the persistence of a native species that is impacted by an exotic natural enemy may require preservation of populations in habitats outside the optimal portion of the native species' distribution.     

Long-term adaptive evolution of Shewanella oneidensis MR-1 for establishment of high concentration Cr(VI) tolerance

• Shewanella oneidensis MR-1 was acclimated to grow with Cr(VI) of 190 mg/L. • Whole genomes from 7 populations at different acclimation stages were sequenced. • Gene mutations mainly related to efflux pumps and transporters. • An adaptation mechanism of MR-1 to high concentration of Cr(VI) was proposed. Acclimation is the main method to enhance the productivity of microorganisms in environmental biotechnology, but it remains uncertain how microorganisms acquire resistance to high concentrations of pollutants during long-term acclimation. Shewanella oneidensis MR-1 was acclimated for 120 days with increasing hexavalent chromium (Cr(VI)) concentrations from 10 to 190 mg/L. The bacterium was able to survive from the highly toxic Cr(VI) environment due to its enhanced capability to reduce Cr(VI) and the increased cell membrane surface. We sequenced 19 complete genomes from 7 populations of MR-1, including the ancestral strain, the evolved strains in Cr(VI) environment on days 40, 80 and 120 and their corresponding controls. A total of 27, 49 and 90 single nucleotide polymorphisms were found in the Cr(VI)-evolved populations on days 40, 80 and 120, respectively. Nonsynonymous substitutions were clustered according to gene functions, and the gene mutations related to integral components of the membrane, including efflux pumps and transporters, were the key determinants of chromate resistance. In addition, MR-1 strengthened the detoxification of Cr(VI) through gene variations involved in adenosine triphosphate binding, electron carrier activity, signal transduction and DNA repair. Our results provide an in-depth analysis of how Cr(VI) resistance of S. oneidensis MR-1 is improved by acclimation, as well as a genetic understanding of the impact of long-term exposure of microorganisms to pollution.     

Tolerance and accumulation of lead in Vetiveria zizanioides and its effect on oil production

Experiments were conducted to evaluate lead tolerance and accumulation in vetiver grass Vetiveria zizanioides (L.), grown in hydroponics and a pot study and to examine the effect of lead on vetiver oil production. Elevated concentrations of lead decreased the length of shoots and roots of plants. However, vetiver grown in highly contaminated soils showed no apparent phytotoxicity symptoms. Lead concentrations in the shoots and roots of vetiver plants grown in hydroponics were up to 144 and 19530 mg kg(-1) and those grown in soil were 38 and 629 mg kg(-1), respectively. Lead had an effect on vetiver oil production and composition by stimulating oil yield and the number of its constituents. Oil yield ranged from 0.4-1.3%; the highest yields were found in plants grown in nutrient solution with 100 mg Pb l(-1) for 5 weeks (1.29%) and 7 weeks (1.22%). The number of total constituents of vetiver oil also varied between 47-143 compounds when lead was presentin the growth medium. The highest number (143) was found in plants grown in soil spiked with 1000 mg Pb kg(-1). The predominant compound was khusimol (10.7-18.1%) followed by (E)-isovalencenol (10.3-15.6%). Our results indicated that lead could increase the oil production of vetiver.     

水体Hg~(2+)对中华绒螯蟹肝胰腺和血淋巴酶活性的影响

以中华绒螯蟹(Eriocheir sinensis)作为暴露生物,检测了水体Hg2+对中华绒螯蟹肝胰腺、血淋巴谷丙转氨酶(GPT)、谷草转氨酶(GOT)、碱性磷酸酶(AKP)和酸性磷酸酶(ACP)活性的影响。结果表明,肝胰腺中GPT和GOT活性随水体中Hg2+浓度(0.01～0.30mg·L-1)升高而降低;中华绒螯蟹血淋巴中GPT和GOT活性变化趋于分化,0～0.05mg·L-1暴露组,随Hg2+浓度升高血淋巴GPT活性迅速上升,0.10～0.30mg·L-1暴露组,随Hg2+浓度升高血淋巴GPT活性迅速下降;GOT活性随着水体Hg2+暴露浓度的升高则持续上升,表现出"剂量-效应"正相关;两种组织中AKP和ACP活性随暴露浓度的升高都表现出"低-高-低"的变化趋势,并且最高值均出现在0.05mg·L-1的Hg2+处理组。4种酶活性对水环境中Hg2+反应灵敏,可作为中华绒螯蟹毒理学评价指标以及重金属监测指标。     

Cytochrome P450 1A activity in liver and fixed wavelength fluorescence detection of polycyclic aromatic hydrocarbons in the bile of tongue-fish (Cynoglossus acrolepidotus, Bleeker) in relation to petroleum hydrocarbons in the eastern Gulf of Thailand.

This investigation was conducted in an area of oil spill along the east coast of Thailand to examine the relations among cytochrome P450 1A activity in liver and PAHs in the bile of the tonguefish and petroleum hydrocarbons in the sediments. PAH sediment concentrations in the reference and oil spill areas were 5.03 +/- 0.42 and 0.21 +/- 0.043 microg(-1) dry weight respectively Cytochrome activity in fish liver from oil spill area was 45.40 +/- 3.50 pmoles/ min/mg protein, almost threefold higher than that from the reference sites. Flourescense detection in bile metabolites at the oil spill area, 69.8 +/- 9.9 flourescense unit was significantly higher than that at the reference sites, 22.9 +/- 5.5 and 22.2 +/- 3.5 fluorescence unit. A strong correlation was found among cytochrome P450 1A activity in liver, PAH of bile metabolites and petroleum hydrocarbons. Both cytochrome and bile metabolites activity decreased seaward varying to the distance from the oil polluted area. We concluded that both detections in tonguefish can be regarded as a complementary biomarkers for the exposure of PAHs in tropical marine environments.     

Effects of Al3+ on pollutant removal and extracellular polymeric substances (EPS) under anaerobic,anoxic and oxic conditions

The highest removal efficiencies of COD and TN were achieved under 10 mg/L of Al³⁺. The highest TP removal efficiency occurred under 30 mg/L of Al³⁺. EPS, PS and PN concentrations increased with the addition of Al³⁺. Sludge properties significantly changed with the addition of Al³⁺. Aluminum ions produced by aluminum mining, electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge. They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation, as well as nitrogen and phosphorus removal. In this study, the effects of Al³⁺ on pollutant removal, sludge flocculation and the composition and structure of extracellular polymeric substances (EPS) were investigated under anaerobic, anoxic and oxic conditions. Results demonstrated that the highest chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies were detected for an Al³⁺ concentration of 10 mg/L. In addition, the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al³⁺. The highest removal efficiency of total phosphorus (TP) was achieved at an Al³⁺ concentration of 30 mg/L. The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones. The addition of Al³⁺ promoted the secretion of EPS. Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al³⁺. At the Al³⁺ concentration of 10 mg/L, fulvic acid and tryptophan fluorescence peaks began to appear, while the majority of protein species and the highest microbial activity were also detected. Low Al³⁺ concentrations (<10 mg/L) could promote the removal efficiencies of COD and TN, yet excessive Al³⁺ levels (>10 mg/L) weakened microbial activity. Higher Al³⁺ concentrations (>30 mg/L) also inhibited the release of phosphorus in the anaerobic zone by reacting with PO₄^3-.     

Polyphenol contents of five of medicinal plants from Cameroon and effects of their extracts on antioxidant capacities of human breast cancer cells

The aim of the study was to investigate the antiproliferative properties of extracts of five plants on breast cancer cells (MDA-MB-231) and their effects on antioxidant activities. The total phenol contents of the extracts were determined to establish a correlation to their antiproliferative effects which were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay. Enzymes involved in oxidative stress were also determined. Total polyphenol contents of the five extracts varied from 170 to 440 mg L^?1 of gallic acid per mg of extract with the highest value for the extract of Sida cordifolia. Cell growth inhibition was observed within 24 h, with inhibitory concentration values ranging from 7.3 to 25 mg L^?1 depending on plant extract. At concentrations between 100 and 200 mg L^?1, all the extracts exhibited significant reduction of cell proliferation in time-dependent and linear manner. The activities of superoxide dismutase and catalase of cells treated for 24 h with the extract of S. cordifolia were 3.5 U per mg protein and 8 mole H₂O₂ consumed per min per mg protein higher than those of cells treated with an extract of Viscum album.     

Production of valued materials from squid viscera by subcritical water hydrolysis

Subcritical water hydrolysis was carried out to produce valued materials from squid viscera, the waste product of fish processing industries. The reaction temperatures for hydrolysis of rawand deoiled squid viscera were maintained from 180 to 280 degrees C for5 min. The ratio of material to water forhydrolysis was 1:50. Most of the proteins from deoiled squid viscera were recovered at high temperature. The protein yield in raw squid viscera hydrolyzate decreased with the rise of temperature. The reducing sugar yield was higher at high temperature in subcritical water hydrolysis of both raw and deoiled squid viscera. The highest yield of amino acids in raw and deoiled squid viscera hydrolyzates were 233.25 +/- 3.25 and 533.78 +/- 4.13 mg g(-1) at 180 and 280 degrees C, respectively. Most amino acids attained highest yield at the reaction temperature range of 180-220 degrees C and 260-280 degrees C for raw and deoiled samples, respectively. The recovery of amino acids from deoiled squid viscera was about 1.5 times higher than that of raw squid viscera.