Fluoride bioaccumulation in the signal crayfish Pacifastacus leniusculus (Dana) as suitable bioindicator of fluoride pollution in freshwater ecosystems

Fluoride bioaccumulation in the signal crayfish Pacifastacus leniusculus (Dana) was examined through field and laboratory studies, considering in the latter the effects of several biotic and abiotic factors: water chloride content, developmental stage, sex, and tissue. The potential use of P. leniusculus as bioindicator of fluoride pollution in freshwater ecosystems was also assessed by testing the capability of juvenile crayfish to release fluoride during depuration periods. After discussing the obtained results, we concluded that: (1) fluoride pollution by industrial effluents may significantly increase the fluoride content in signal crayfish inhabiting polluted freshwater ecosystems; (2) although high chloride levels in the aquatic medium may significantly reduce the fluoride content in signal crayfish exposed to fluoride pollution conditions, fluoride bioaccumulation can still occur in significant amounts; (3) sex does not seem to be an important biotic factor affecting fluoride bioaccumulation in signal crayfish; (4) in contrast, the type of tissue is an important biotic factor affecting fluoride bioaccumulation in signal crayfish, with the exoskeleton accumulating more fluoride than the muscle, in absolute terms, but with the muscle accumulating more fluoride than the exoskeleton, in relative terms (in relation to pre-effluent/control values); (5) the developmental stage seems to be another important biotic factor affecting fluoride bioaccumulation in signal crayfish, with juveniles being able to accumulate fluoride more rapidly than adults under fluoride pollution conditions; (6) although, during depuration periods, signal crayfish may significantly release fluoride, they can still retain significant amounts of the fluoride previously bioaccumulated during exposure periods. We can overall conclude that fluoride bioaccumulation in signal crayfish may be used as suitable bioindicator of fluoride pollution in those freshwater ecosystems where it is already present. However, this notable capability to accumulate and retain fluoride poses a potential risk to human health when signal crayfish from fluoride polluted areas are consumed.     

蚕豆叶片SOD活性监测大气SO2污染的可行性研究

 本文从实验室熏气和野外大气暴露两方面对利用蚕豆叶片SOD活性评价和监测大气SO2污染的可行性进行了研究。低浓度SO2(0.1312、0.2601mg·m-3)处理,引起叶片SOD活性升高,一定时间后,SOD活性趋于稳定,且0.2601mg·m-3SO2处理时,SOD活性较高,表现出SOD活性增量与SO2浓度相关,为利用SOD活性监测和评价SO2污染提供了可能性。大气暴露试验结果表明SOD活性与大气硫酸盐化速率存在极显著的相关性。利用SOD活性和大气硫酸盐化速率分别对大气SO2污染程度进行了评价,结果基本一致,并根据SOD活性估测了大气硫酸盐化速率,符合程度较高,置信分析表明估测结果可信。以上结果表明,利用蚕豆叶片SOD活性监测和评价大气SO2污染是可行的。     

Internal intensity standards for heme protein UV resonance Raman studies: excitation profiles of cacodylic acid and sodium selenate.

We examine the utility of SO4(2-), ClO4-, cacodylic acid, and SeO4(2-) as internal intensity standards for Raman spectral measurements of protein structure. We find that 0.1 M SO4(2-) and ClO4- perturb the protein tertiary structure of aquomethemoglobin (met-Hb) and its fluoride (met-HbF) and azide (met-HbN3) complexes. Changes occur for the tryptophan near-UV absorption bands, the iron spin state is altered, and the fluoride ligand affinity decreases. Concentrations of ClO4- and SO4(2-) as low as 0.1 M suppress the met-HbF quaternary R----T transition induced by the allosteric effector inositol hexaphosphate (IHP). In contrast, similar concentrations of cacodylic acid and SeO4(2-) show little effect on the hemoglobin tertiary or quaternary protein structures or upon the R----T transition induced by IHP. We measure the Raman cross sections of cacodylic acid and SeO4(2-) between 218 and 514.5 nm and find that for UV excitation they are ca. 5-fold larger than ClO4- or SO4(2-). Thus, cacodylic acid and selenate can be used at lower concentrations. Cacodylic acid and SeO4(2-) are superior Raman internal intensity standards for protein structural studies.     

Solvent effects on substrate and phosphate interactions with the (Na+ + K+)-ATPase

(Na+ + K+)-ATPase activity of a dog kidney enzyme preparation was markedly inhibited by 10-30% (v/v) dimethyl sulfoxide (Me2SO) and ethylene glycol (Et(OH)2); moreover, Me2SO produced a pattern of uncompetitive inhibition toward ATP. However, K+-nitrophenylphosphatase activity was stimulated by 10-20% Me2SO and Et(OH)2 but was inhibited by 30-50%. Me2SO decreased the Km for this substrate but had little effect on the Vmax below 30% (at which concentration Vmax was then reduced). Me2SO also reduced the Ki for Pi and acetyl phosphate as competitors toward nitrophenyl phosphate but increased the Ki for ATP, CTP and 2-O-methylfluorescein phosphate as competitors. Me2SO inhibited K+-acetylphosphatase activity, although it also reduced the Km for that substrate. Finally, Me2SO increased the rate of enzyme inactivation by fluoride and beryllium. These observations are interpreted in terms of the E1P to E2P transition of the reaction sequence being associated with an increased hydrophobicity of the active site, and of Me2SO mimicking such effects by decreasing water activity: (i) primarily to stabilize the covalent E2P intermediate, through differential solvation of reactants and products, and thereby inhibiting the (Na+ + K+)-ATPase reaction and acting as a dead-end inhibitor to produce the pattern of uncompetitive inhibition; inhibiting the K+-acetylphosphatase reaction that also passes through an E2P intermediate; but not inhibiting (at lower Me2SO concentrations) the K+-nitrophenylphosphatase reaction that does not pass through such an intermediate; and (ii) secondarily to favor partitioning of Pi and non-nucleotide phosphates into the hydrophobic active site, thereby decreasing the Km for nitrophenyl phosphate and acetyl phosphate, the Ki for Pi and acetyl phosphate in the K+-nitrophenylphosphatase reaction, accelerating inactivation by fluoride and beryllium acting as phosphate analogs, and, at higher concentrations, inhibiting the K+-nitrophenylphosphatase reaction by stabilizing the non-covalent E2.P intermediate of that reaction. In addition, Me2SO may decrease binding at the adenine pocket of the low-affinity substrate site, represented as an increased Ki for ATP, CTP and 3-O-methylfluorescein phosphate.     

氟污染区绿化树种的选择

前言凡使用含氟矿石(如冰晶石、磷矿石等)作原料的工厂,在碾磨、加热、酸化等过程中,以及利用含氟化合物作为接触剂、助熔剂的各种工艺过程的生产中,都会散发出大量的含氟废气与粉尘污染环境,给农林业生产及人     

大气氟污染对达乌尔黄鼠及其环境的影响

本文研究大气氟污染对达乌尔黄鼠及其环境的影响。研究区内的钢厂为大气氟污染的点源。在研究区内选6个取样点,分别取黄鼠大腿骨骨样、植物样和土样。 黄鼠大腿骨骨灰、植物和土壤的含氟量是随与污染源的距离和方向的不同而变化的,离污染源愈远各样品的含氟量愈低。污染源西北方向,靠近污染源的取样点污染特别严重。但是,黄鼠体重与其大腿骨骨灰含氟量间没有明显相关。黄鼠可认为是对氟污染的“耐干扰种”。 在研究区内,氟污染对植物群落的种类、生物量和群落的多样性没有明显地影响。大腿骨骨灰和植物含氟量间存在一定的回归关系,其关系式为Y=27.16X~1.02。     

构树钟乳体毛的发育及钟乳体成分研究

构树(Broussonetis Papyrifea)幼茎、芽、叶的表面具钟乳体毛。它是一长圆锥状单细胞毛,基部有无管漏斗状基座包裹,腔内有呈轮纹状沉积的钟乳体。钟乳体毛发生很早,自芽的第3幼叶(自叶原基数起)开始发生。原表皮细胞进行不均等的垂周分裂,其小的发育成表皮细胞,大的发育成钟乳体毛。基座由原表皮细胞垂周及横分裂而形成。其内钟乳体发育较迟,要等叶长至6cm,宽4—5cm时,才从毛尖或毛尖之下侧壁处开始沉积。构树钟乳体成分中含硫酸钙,这可能正是构树积累硫的速度快,净化大气中有害的SO2气体和可能抗SO2污染很强的原因。对筛选和培育抗SO2毒气更强的植物提供了参考。     

大气污染对珠江三角洲森林及土壤影响的初步研究

于1998年4月至1999年3月采用定点测定和面上调查相结合的方法,开展大气污染对珠江三角洲森林生长及其土壤酸碱性的肥力特性的影响研究。初步结果表明：大气污染引起珠江三角洲的地区发生大面积、高频率的酸雨,主要的污染物有SO、NOx、悬浮颗粒物等;随着污染程度的增大,森林土壤pH值降低,SO4^2-和AI^3 质量浓度增大;马尾松、湿地松叶片叶绿素含量降低,生长衰退甚至死亡;但不同树种对大气污染敏感程度不同,种植马占相思比马尾松更能增加林地对酸雨缓冲力和提高土壤肥力。     

二氧化硫代谢衍生物对大鼠海马CA1区神经元钠电流的影响

实验采用全细胞膜片钳技术 ,研究了SO2 代谢衍生物亚硫酸钠和亚硫酸氢钠 (两者分子比为 3∶1)对大鼠海马CA1区神经元钠电流的影响。结果表明 ,SO2 代谢衍生物可剂量依赖性地增大钠电流 ,剂量为 10和 10 0μmol/L时 ,钠电流分别增大 5 0 .5 9± 19.0 8%和 82 .0 6± 18.5 1%(n =15 ) ;此外还与电压呈依赖性关系 ,但不具有频率依赖性 ;10 μmol/LSO2 代谢衍生物不影响钠电流的激活过程 ,却非常显著地影响其失活过程 ,作用前后的半数失活电压分别为 - 6 9.71± 4.6 7和 - 5 3.2 7± 4.95mV (n =10 ,P <0 .0 1) ,但不改变失活曲线的斜率因子。实验结果提示 ,SO2 衍生物具有类似神经毒物的作用 ,大气SO2 污染可能与一些中枢神经系统疾病的发生有关。