Total and methyl mercury in small marine biota caught off the Coast of Chennai,India

Abstract

This study reports the concentrations of total mercury and methyl mercury in sixteen families of marine biota caught off the coast of Kasimedu in Chennai, India, an important but understudied fish landing region. These included the commonly caught croakers, carangids, rays, goat fish, anchovies, crabs, and prawns. There was no correlation between total mercury or methyl mercury with fish length or mass. All concentrations were lower than the Food Safety and Standards Authority of India limits (total mercury = 500?μg/kg; methyl mercury = 250?μg/kg). Some values were above screening levels (total mercury >40?μg/kg wet weight) when considering possible adverse effects in predatory fish that consume the analyzed biota.

Abbreviations: dw: dry weight; MeHg: methyl mercury; THg: total mercury; ww: wet weight     

Seasonal ovarian cycle in freshwater teleost, Labeo rohita (Ham.) in Tarai region of Uttaranchal

Seasonal ovarian cycle, based on histophysiological changes, and correlative variations in liver were studied in an Indian major carp, Labeo rohita reared in captivity under ambient environmental conditions in Tarai region of Uttaranchal. The oocyte features used for marking ovarian cycle included nuclear-ooplasmic ratio, yolk vesicle incorporation into ooplasm, number and size of nucleolus and differentiation of follicular layer. Based on these features the ovarian cycle in L. rohita was divided into five phases i.e. resting, preparatory, pre-spawning, spawning and post-spawning/regression. The resting and preparatory phases were characterized by the dominating presence of chromatin-nucleolar and yolk-vesicle stage oocytes. The pre-spawning phase ovary was marked by the prevalence of yolk globule stage oocytes having cortical alveoli and differentiating follicular wall. The oocytes containing densely packed yolk-granules and large masses of yolk vesicles and also exhibiting germinal vesicle movement (GVM) signified the ovary of spawning phase. The ovary in regression phase contained pre-ovulatory atretic oocytes and significant number of oogonia. The histophysiological changes in liver showing augmented biosynthetic activity during preparatory and pre-spawning phases seemed well correlated with the gonadal development. The increasing water temperature and day-length apparently was favourable for the gonadal development in L. rohita.     

Relationship between growth and biochemical indices in laboratory-reared juvenile Japanese flounder (Paralichthys olivaceus), and its application to wild fish

In order to estimate growth rates based on biochemical indices of the liver of wild Japanese flounder (Paralichthys olivaceus), juveniles were reared at six ration levels (0, 0.5, 2, 4, 6 and 8% body weight day⁻¹) in the laboratory for 14 days, and the relationship between their growth rates and biochemical indices (RNA/DNA, protein/DNA, triglyceride/DNA, phospholipid/DNA and cathepsin D activities) were determined. Positive and approximately linear relationships were seen between growth rates and the indices of RNA/DNA, protein/DNA and phospholipid/DNA. The triglyceride/DNA ratio decreased with increasing growth rates up to approximately 1% body weight day⁻¹, then increased linearly with increasing growth rates. There was no significant correlation between growth rates and cathepsin D activity, and the highest values were obtained in the starved fish. Compared with laboratory-reared specimens, wild specimens of similar sizes were found to have significantly larger livers. The RNA/DNA, protein/DNA and phospholipid/DNA ratios of wild specimens fell in a broad range between ration groups of reared juveniles. The protein/DNA ratios of wild specimens were low and outside the range of the reared juveniles at six ration levels. In contrast, the levels of cathepsin D activity of wild fish were highest compared to the reared fish. Estimated growth rates of wild fish from the RNA/DNA, protein/DNA and phospholipid/DNA regressions obtained from the rearing experiment were 1.66, −1.74 and 0.10% day⁻¹, respectively. Based on our results, the RNA/DNA index may be regarded as the most valid and reliable growth estimator. It is noted that the larger liver size, the lower liver protein/DNA ratio and the unexpectedly high level of cathepsin D activities of wild specimens found in this study may reflect the different metabolic conditions of fish reared in the laboratory compared to those collected in the field. Received: 29 February 2000 / Accepted: 26 August 2000     

DLL-1菌对甲基对硫磷农药的降解作用及其降解机理

研究了假单胞菌 (DLL - 1)在水溶液介质中降解甲基对硫磷的性能与影响因素及其降解机理。结果表明 ,当菌体浓度为 10 5个·ml-1时 ,即发生快速的降解作用 ,3h时 ,降解率达 88.5 %。在pH为 5 .0、7.0和 9.0条件下 ,DLL - 1菌均产生对甲基对硫磷农药的高效降解作用。采用气相色谱 -质谱联用技术与离子色谱法 ,测定了DLL - 1菌 -甲基对硫磷作用过程产生的中间产物和最终产物 ,表明对硝基苯酚为主要中间产物 ,且DLL - 1菌能将其进一步降解为NO2 -和NO3 -。     

甲基对硫磷降解菌DLL-1的分离、鉴定及降解性研究

从长期施用甲基对硫磷的污染土壤中分离到一株能以甲基对硫磷为唯一碳源生长且能将其完全矿化的细菌 Ｄ Ｌ Ｌ－ １ ,经鉴定,为邻单胞菌（ Ｐｌｅｓｉｏｍｏｎａｓ ｓｐ ．） ．该菌株３ ｈ 内对５０ ｍｇ／ Ｌ甲基对硫磷的降解率为９３ ％ ,２４ｈ 内对５０ ｍｇ／ Ｌ甲基对硫磷的降解率为９５ ％ 以上．在葡萄糖铵盐培养基中, Ｄ Ｌ Ｌ１ 对甲基对硫磷的耐受浓度和降解速度均增大．降解曲线表明延滞期内,菌体依靠上一生长阶段分泌的酶类对甲基对硫磷进行降解,一旦菌体开始生长,则检测不到中间代谢产物对硝基苯酚的存在．生长情况和粗酶液试验均显示 Ｄ Ｌ１ 优良的降解性状     

Short-term and long-term survival studies in Rana tigrina tadpoles with reference to methyl parathion toxicity

Toxicity of methyl parathion was studied on survival of Rana tigrina tadpoles. The LC50 values for short-term (upto 96 h) and long term studies (hatching to froglet) were determined. The LC50 values for 96 h and the total larval period were 4.36 and 1.30 ppm respectively. The toxicity of methyl parathion enchanced in relation to increase in concentration and duration. Teratological defects such as scoliosis and failure in emergence of fore limb were noticed. Safe levels were calculated for short-term (0.1 ppm) and long-term (0.03 ppm) studies. The present work stresses the neccessity of long term study especially for the developing amphibians.     

Fenvalerate-induced macromolecular changes in the catfish,Clarias batrachus

The effects of sublethal concentration of fenvalerate on DNA, RNA, RNA/DNA ratio and protein contents were estimated in gill and kidney tissues of an air breathing fish, Clarias batrachus. Fenvalerate reduced the DNA content in gill, whereas it did not produce any significant effect on DNA in kidney. This tissue-specific change in DNA content may be due to differential effects of fenvalerate or its metabolite(s) on synthesis and/degradation of DNA in gill and kidney cells of the fish. RNA and protein contents declined substantially in both the tissues in response to fenvalerate treatment. However, RNA/DNA ratio remains unchanged. It indicates that decrease in protein content in response to fenvalerate treatment might have been brought about by reduce rate of translation of messenger (mRNA) without a decrease in concentration of ribosomes.     

Glutathione S-transferase activity in rats exposed to methyl parathion

Methyl parathion is an organophosphate insecticide that has been used in agriculture and the domestic sector for several years. This pesticide and others, arriving through different processes, exert significant effects on water quality with serious consequences for environmental and human health. The main objective of this study was to investigate the changes of Glutathione S-transferase enzyme activity in methyl parathion exposed rat tissues. For this purpose, wistar rats (Rattus norvegicus) were injected intraperitoneally with 7 mg kg^?1 dose of methyl parathion, while corn oil was applied to control groups in the same way. The liver, kidneys, brain and small intestine were quickly removed after 0, 2, 4, 8, 16, 32, 64, and 72 hours of injection of methyl parathion and the glutathione S-transferase activity was determined in these tissues. As a result it was seen that glutathione S-transferase activity increases in all tissues in the group of male and female rats to which methyl parathion was given. The increase of glutathione S-transferase activity may be a result of methyl parathion's toxic effect because it is one of the most important enzymes of detoxification metabolism.     

Electrochemical determination of methyl parathion using a modified electrode

Electrochemical studies of pesticides using various electrode systems attain prominence in recent years because of their application in trace determinations. Cyclic voltammetric studies of methyl parathion on a glassy carbon electrode at various pH in 50% aqueous ethanol medium were carried out. Influence of pH led to the selection of pH 1.0 as the best pH for the electroanalysis of methyl parathion. The number of electrons transferred was determined using controlled potential coulometry. On the basis of the results a probable reduction mechanism was proposed. Cyclic voltammetric studies of methyl parathion using polypyrrole deposited and sodium montmorillonite clay modified electrodes in the presence of cetyl trimethyl ammonium bromide were carried out. The clay-modified electrode and the reduction peak around ?0.2?V were selected for stripping analysis owing to their maximum current response. The experimental parameters were optimized using the differential pulse stripping mode. A calibration plot was made. The determination limit and standard deviations were arrived. The applicability of the method was also verified in a sample soil analysis.     

Sol-gel immobilisation of methyl parathion degrading bacteria isolated from agricultural areas of Pakistan

The following areas are discussed in this paper: immobilisation of bacterial consortium in sol-gel; methyl parathion degradation and bioremediation applications; evaluation of indigenous bacterial isolates of contaminated soils. Bacterial strains were isolated from agricultural areas of Pakistan which were contaminated with methyl parathion. A bacterial consortium of seven (out of 64) Enterobacteriaceae isolates including Citrobacter, Enterobacter and Proteus vulgaris capable of degrading methyl parathion (enzyme activity ranging 410–675 mU mL^?1 for individual isolates and 982 mU/mL for consortium) was selected and subsequently immobilised in tetraethyl orthosilicate (TEOS) and sodium-silicate-based sol-gel matrices. Cell viability of suspended and immobilised bacterial consortium was monitored using a minimal salt medium supplemented with methyl parathion. The results indicate that sol-gel immobilisation can be helpful to increase the shelf life of methyl parathion degrading bacterial strains along with preservation of biological activity for bioremediation applications in field.     

鱼类肝脏微粒体对于硫代磷酸酯类杀虫剂活化代谢率的种间差异(Species-Related Difference of Liver Microsomes of Fish in Activation of Organothiophosphorus Insecticides)

为了弄清鱼类肝脏微粒体细胞色素P450s(CYPs)对于硫代磷酸酯类杀虫剂活化代谢率的种间差别,选用斑马鱼Brachydanio rerio、麦穗鱼Pseudorasbora parva、剑尾鱼Xiphophorus helleri、篮鳃太阳鱼Leponus macrohirus四种鱼作为受试生物,选用对硫磷、马拉硫磷、毒死蜱三种硫代磷酸酯类杀虫剂作为受试药剂,以外源乙酰胆碱酯酶(AchE)的抑制率为指标,在离体状态下间接测量了杀虫剂活化代谢物的相对生成量.离体试验表明,对于对硫磷,活化代谢物生成量的高低顺序为:斑马鱼、剑尾鱼、麦穗鱼>太阳鱼(p<0.05),最高的麦穗鱼和最低的太阳鱼之间相差10.0倍;对于马拉硫磷和毒死蜱,活化代谢物生成量的高低顺序均为:剑尾鱼>太阳鱼>斑马鱼、麦穗鱼(p<0.05),最高的剑尾鱼和最低的麦穗鱼之间的分别相差66.9和137倍.毒性测定表明,对于对硫磷、马拉硫磷和毒死蜱,四种鱼96hLC50之间的最大差别分别是45、18和77倍.对马拉硫磷而言,96hLC50的种间差异特征与活化代谢物生成量的种间差异特征比较吻合,而对于对硫磷和毒死蜱而言,两者之间的吻合度较低.研究证实了肝脏CYP在活化硫代磷酸酯杀虫剂方面具有明显的种间差异,同时也证实仅以活化代谢物的离体生成量这一指标来衡量鱼类对于硫代磷酸酯杀虫剂的敏感性,其结论可能会较大幅度地偏离生测结果.尽管如此,本研究证实在所测的鱼类当中,斑马鱼属于CYP活性较低的鱼种,而这一特性很可能是造成斑马鱼对于硫代磷酸酯杀虫剂的敏感性偏低的重要原因.     

UV-C light-enhanced photo-Fenton oxidation of methyl parathion

The photodegradation of aqueous solutions containing 0.2 mM methyl parathion has been studied through the optimization of the [H₂O₂]/[Fe³⁺] ratio in a Fe³⁺/H₂O₂/UV-C flow system of 1.3 L capacity. The decay kinetics and TOC abatement have been analyzed for the experiments performed at pH 3.0 and room temperature. All experiments lead to the total methyl parathion destruction after a few minutes, following a pseudo-first-order decay kinetics. Total mineralization can be reached after 120 min at the optimum ratio found, due to the synergistic effect of the very oxidizing hydroxyl radical (^·OH) produced via the Fenton reagent and the effective photodecarboxylation at 253.7 nm.     

Influence of sublethal ammonia toxicity on some physiological parameters of Labeo rohita (Hamilton-Buchanan) fingerlings

Fingerlings of Labeo rohita subjected to sublethal unionized ammonia (0.132mg/l) for 30 days exhibited significant changes. Increase in haemoglobin, haematocrit, plasma cortisol, plasma glucose, plasma cholesterol and plasma lactic acid levels whereas, decrease in plasma chloride, liver and muscle glycogen, hepatosomatic index and DNA/RNA ratio of muscles with stable plasma protein was observed. Metabolic recovery was not observed within 30 days of exposure.     

Resistenzadaptation bei gehemmeter Proteinbiosynthese. Versuche mit Actinomycin D an dem Fisch Rhodeus amarus

Rhodeus amarus acclimated to 10° or 20°C die at 31.7° or 36.4°C, respectively (cessation of operculum movements). After raising the adaptation temperature (AT) from 10° to 20°C, adaptation is complete after 8 days. The toxicity of actinomycin D, injected intraperitoneally, is AT-dependent (e.g. at 5°C, LD_{50–7 days}=0.8 μg/g fish; at 25°C, LD_{50–7 days}=0.35 μg/g fish). In the following experiments 0.5 μg actinomycin/g fish were used. After actinomycin-injection, RNA-values in white dorsal muscle decreased about 50% within 12 h and the values of control individuals were finally attained after 16 days. Following an AT-change from 10° to 20°C, DNA-values in the white dorsal muscle increased about 10%, RNA-values about 30%, within 12 h. However, in fish injected intraperitoneally with actinomycin, no increase in DNA or RNA was noticed. Actinomycin injection per se causes increased heat resistance. This process lasts 10 days. If AT is raised now from 10° to 20°C, the new resistance level is reached later. The control fish gain resistance at a rate of about 1 C°/day during the first days after the temperature change. Actinomycin-treated individuals, however, exhibit an increase of 0.25 C°/day. Inhibition of resistance adaptation due to proteinbiosynthesis-inhibitors supports the view that protein synthesis is of importance for adjustments in heat resistance of intact animals.

     

Effect of curacron toxicity on the total serum protein content of Cyprinus carpio

An experiment was conducted on freshwater fish Cyprinus carpio to study the effect of the pesticide curacron on total serum protein. Curacron is an organophosphate pesticide and used by the farmers to protect their crops. This pesticide reaches the aquatic ecosystem by direct or indirect means and affects aquatic fauna. LC50 for curacron for C. carpio was calculated by the log-dose/probit regression line method and found to be 0.38?ppm at 96?h. Three sub-lethal concentrations (0.1, 0.01, and 0.001?mL?L^?1) were selected to expose the fish for 1, 7, 14, and 21days. Changes in total serum protein were observed at all pesticide concentrations and exposure periods. Total serum protein was decreased from control. At 1 and 7 days, the decrease was quantitative at all concentrations, while at 14 and 21 days, the fall was significant at all concentrations. Hence, human population may be at risk by consuming these contaminated fish.     

Study by evolution of nucleic acid content of prepuberal growth in the shrimp Crangon vulgaris

Growth of the shrimp Crangon vulgaris was studied by following the evolution of its nucleic acid concentration and total content. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) analysis were effected on homogenates of whole shrimps. Cell multiplication was estimated from evolution of total DNA content, and cell size increment from evolution of fresh weight: DNA ratio. DNA puric bases ratio and RNA monoribonucleotides percentages were constant throughout the investigation period. A decrease in DNA concentration was observed from 50 to 20 M/g dry defatted weight (DDP), when fresh weight increases from 40 to 570 mg. This decrease was more marked in the first half of the period studied (prepuberal phase). The DNA content in the whole shrimp increases with fresh weight without slowing down at sexual maturity. However, at the beginning of the prepuberal phase the cell-multiplication rate seems to be graduated rather than continuous; this is still to be explained. Cell size, calculated from fresh weight: DNA ratio, increases until the shrimp weighs 300 mg; beyond this weight, cell increment proceeds much more slowly. The weight gain of shrimps throughout the growth period studied is mainly attributable to hyperplasia — which occurs constantly — while hypertrophy insures only 21% weight increment in the largest shrimps. As protein content, RNA content is a linear function of shrimp weight. RNA:DNA ratio evolution is similar to that of cell size and protein content. We suggest that cells have attained a physiological balance when shrimps reach a weight of 300 mg.     

金矿区中国林蛙体内DNA甲基化水平

采集金矿附近山区河流水质、沉积物和当地两栖类动物中国林蛙样品,应用高效液相色谱仪测定污染区和对照区林蛙体内各组织器官的胞嘧啶(c)和5-甲基胞嘧啶(5-mc)含量,探讨因金矿开采引起的汞污染以及对林蛙体内组织器官DNA甲基化水平的变化,研究汞胁迫下,两栖类动物体内分子水平的影响。结果表明:金矿开采区河流水质和沉积物已受到甲基汞污染,污染区林蛙体内甲基汞含量远高于对照区;林蛙体内各组织器官中DNA甲基化水平发生不同的变化:污染区林蛙肝脏和皮肤中DNA甲基化水平高于对照区,肌肉和脑干DNA甲基化水平低于对照区;雄性林蛙肝脏和脑干DNA甲基化水平高于雌性,肌肉和皮肤DNA甲基化水平却低于雌性。以上结果说明汞胁迫下,中国林蛙体内组织器官DNA甲基化水平可以发生一定的变化,环境中重金属汞离子进入林蛙体内含量的不同,可以促进或抑制其体内甲基化水平的变化,引起基因毒性作用。     

两株联合降解甲基一六○五菌的分离及其特性研究

从农药厂污泥中分离得到一个降解甲基一六○五的混合菌群,该菌群由两种菌 Ｍ６ 和 Ｐ３ 组成,初步鉴定均为假单胞菌属（ ｐｓｅｕｄｍｏｎａｓ ．ｓｐ） ． Ｍ６ 菌具有一硫代磷酸酯键水解酶,能够催化甲基一六○五水解为对硝基酚, Ｐ３ 具有对硝基酚降解能力． Ｍ６ 和 Ｐ３ 各自均不能彻底矿化甲基一六○五． Ｍ６ 与 Ｐ３ 混和可以彻底降解甲基一六○五．质粒消除实验表明, Ｓ Ｄ Ｓ、吖啶橙（ Ｏ Ａ） 、丝裂霉素及几种消除剂混和处理均不能使 Ｍ６ 和 Ｐ３ 丧失一六○五水解和对硝基酚降解能力,质粒检测发现在 Ｍ６ 中检测到质粒条带,而 Ｐ３ 中未检测到质粒条带     

Identification of a sensitive index during fish bioassay of an azo dye methyl red (untreated and treated)

Acute and chronic toxicity of methyl red (untreated) was examined on a freshwater fish Poecilia reticulata, using indices viz; mortality, reduction in RBC counts and their morphological abnormality (poikilocytosis and anisocytosis). Similar studies (acute toxicity) were also made in physicochemically and biologically treated methyl red. Data comparison of these four indices revealed poikilocytosis as the most sensitive index, since it measured higher toxicity of methyl red when fish mortality was either minimum at its low concentration (5 ppm) during both acute and chronic toxicity or even nil in the biologically treated 100 ppm methyl red, during acute toxicity. Mortality was next to poikilocytosis though it ranked 1st at higher concentration of methyl red during acute toxicity. The reduction in RBC counts however, was found to be the most sensitive parameter only in case of prolonged exposure (4 weeks) to 5 ppm methyl red. Amongst the four indices used for quantifying toxicity; anisocytosis was found to be the least expressive. Based on these findings we recommend quantification of data on fish mortality and poikilocytosis during acute toxicity whereas reduction in RBC counts and poikilocytosis during chronic exposure to methyl red.     

Monitoring toxicity of an azo dye methyl red and a heavy metal Cu,using plant and animal bioassays

Toxicities of an azo dye methyl red and a heavy metal copper (Cu) were quantified, using growth and mortality as end points, in four plant species and three animal species by subjecting them to short-term (4 days for animals, 10 days for plants) static bioassays. Lemna aequinoctialis Welwitch (EC₅₀: 7–16 ppm) was found to be the most sensitive species for methyl red, Ceratophyllum demersum L. (EC₅₀: 25 ppm) and Lactuca sativa L. (EC₅₀: 56 ppm) were intermediate, while Oryza sativa L. shows reduction in seedling vigor (9–27%) of <50%, being the least sensitive amongst the tested plant species. Methyl red toxicity is almost 3–5-fold higher in growing medium (pH = 5.8–6.0), even at high nutrient levels, while Cu toxicity is higher in nutrient-poor alkaline medium at alkaline pH (8.3–8.7; EC₅₀: Ceratophyllum = 104–200 ppb; Lemna = 100–170 ppb) compared to nutrient-rich acidic medium (pH = 5.4–5.7; EC₅₀: Ceratophyllum = 2600–3175 ppb; Lemna = 4350–4715 ppb). Rice tolerance (EC₅₀: 6500 ppb) was found to be higher than hydrophytes while lettuce was most tolerant to Cu. Fish sensitivity toward the test chemicals was almost parallel to Ceratophyllum and Lemna [Gambusia affinis Baird and Gerard (LC₅₀: 250 ppb for Cu) and Poecilia reticulata Peters (LC₅₀: 24 ppm for methyl red)]. Similar to the plants, dye toxicity increased markedly (LC₅₀: 7 ppm) in the acidic medium (pH = 6.0). Amongst the tested organisms, Daphnia was found to be most sensitive to methyl red (EC₅₀: 6 ppm) while its sensitivity to Cu (EC₅₀: 230 ppb) was similar to hydrophytes and fish. Initially, the combination of dye and Cu (at their sublethal concentrations) had additive effects in duckweed, while dye concentration ruled afterward. These results indicate that hydrophytes and animals are equally sensitive toward the test chemicals. Dye toxicity in hydrophytes and fish was pH dependent, while in the case of Cu, it is related to the nutrient status of the growth medium of plants.