DNA strand breaks in grass shrimp embryos exposed to highway runoff sediments and sediments with coal fly ash

Embryo production was reduced in female grass shrimp exposed to sediments with added coal fly ash and to sediments collected from an estuarine station containing high PAH concentrations due to its proximity to a highway storm drain. Grass shrimp embryos exposed to pore water from the high PAH and high metal sediments showed both reduced hatching and increases in DNA strand breaks (comet assay). Sediments with added coal fly ash had high concentrations of vanadium and selenium which may have contributed to effects similar to those observed with sediments with high PAH. The embryo pore water bioassay (hatching/DNA strand breaks) gave results comparable to those observed for reproduction effects (reduced embryo production/embryo hatching) with female grass shrimp exposed to whole sediment.     

Effects of genotoxic compounds on DNA and development of early and late grass shrimp embryo stages

Early and late developmental stages of grass shrimp embryos were exposed to different concentrations of two genotoxicants, 2-methyl-1,4-naphthoquinone (MNQ) and 4-nitroquinoline-N-oxide (NQO). DNA strand breaks were assessed by the comet assay while embryo development effects were determined by % of embryos hatching. Early embryo stage embryos were significantly more sensitive to genotoxicants than late stages. For example, all stage 4 embryos failed to hatch at 1 microM NQO while 95% of stage 8 hatched at this concentration. High DNA tail moments, which are a measure of the number of DNA strand breaks, were found in late stage embryos exposed to genotoxicants. Early stage embryo development was effected by low concentrations of genotoxicants but no changes were observed in DNA tail moments. We suggest that high DNA moments in late embryo stages reflect high DNA repair activity, while early stages may lack a fully developed DNA repair system.     

Comet assays to assess DNA damage and repair in grass shrimp embryos exposed to phototoxicants

Exposure of grass shrimp (Palaemonetes pugio) embryos to four compounds (anthracene, pyrene, alpha-terthienyl, methylene blue) along with solar exposure resulted in extensive DNA strand damage using the comet assay. DNA tail moments of embryos exposed to these chemicals in the dark ranged from 1.8 to 4.3, while exposure to chemicals and solar resulted in tail moments of 14.3-15.3. Reduction of DNA tail moments when solar exposed embryos were transferred to the dark, suggested DNA repair systems were active. The comet assay can be used to follow both DNA damage and repair following exposure to phototoxic chemicals.     

Histopathological changes in grass shrimp exposed to chromium, pentachlorophenol and dithiocarbamates

This report deals with the histopathological/ultrastructural changes in various tissues of grass shrimp (Palaemonetes pugio) exposed to hexavalent chromium, pentachlorophenol (PCP) and two dithiocarbamate formulations: Aquatreat DNM-30® (15 % sodium dimethyl dithiocarbamate plus 15 % disodium ethylene bis-dithiocarbamate) and Busan-85® (50 % potassium dimethyl dithiocarbamate). The pathological alterations induced by dithiocarbamates and PCP were most severe and first evident in the gills. Of the biocides tested, the dithiocarbamates caused the most extensive branchial damage—the so-called black gill syndrome, involving early melanization and eventual lamellar truncation. Hexavalent chromium, on the other hand, did not induce marked changes in the gills, but it caused invasive melanized cuticular lesions (particularly at the articulations of the pereiopods, pleopods and abdominal segments). Additionally, chromium caused apparent labyrinth hypoactivity in the antennal glands, whereas the dithiocarbamates seemed to induce labyrinth hyperactivity. Hepatopancreatic histopathology was more severe in shrimp exposed to chromium and PCP than in dithiocarbamate-exposed shrimp. The apparent mitotic activity in the hepatopancreas was increased in Aquatreat-exposed shrimp and suppressed in chromium-exposed shrimp; many mitotic figures in the latter case were abnormal. All four compounds caused varying degrees of midgut epithelial hypertrophy, cytoplasmic vacuolization and diminution of basal tubular endoplasmic reticulum, but only PCP caused widespread rupture of midgut epithelial cell apices. Additional notable ultrastructural anomalies included: mitochondrial compartmentalization in PCP-exposed shrimp; mitochondrial fusion in dithiocarbamate-exposed shrimp; and unusual intranuclear inclusions in different tissues of chromium-exposed shrimp. These pathological changes point to differences in the mechanisms of pollutant toxicity and indicate their potential use in the biological monitoring of aquatic pollutants.     

过硫酸氢钾复合物对对虾养殖底泥硝化作用、氨氧化微生物丰度和群落结构的影响

采用在模拟池塘中投放过硫酸氢钾复合物（KMPS）进行对比实验的方法,探究KMPS对养殖底质硝化作用的影响。通过对氨氮和亚硝态氮含量的检测,探究对不同时期氮素转化的影响,低频率高剂量投放组中的氨氮和亚硝态氮含量显著降低,而高频率低剂量组中氨氮和亚硝态氮的含量显著上升。高频率低剂量KMPS的投放使氨氧化古菌（AOA）和氨氧化细菌（AOB）丰度降低,而低频率高剂量KMPS的投放不会造成丰度降低,而且还表现出部分时期AOB丰度的上升。进一步对群落结构进行分析发现KMPS的投放使AOA群落中Nitrosopumilu属相对丰度降低,Nitrososphaera属的相对丰度上升,这种相对丰度的变化与KMPS的投放方式无关;但AOB群落受到KMPS投放方式的影响,低频率高剂量的KMPS投放下AOB群落优势属相对丰度显著提高。以上结果均说明低频率高剂量KMPS的投放起到了促进底质硝化作用的效果。同时,可为KMPS用于对虾养殖池塘底质改良开辟一个新的途径。     

DNA strand breaks (comet assay) and embryo development effects in grass shrimp (Palaemonetes pugio) embryos after exposure to genotoxicants.

Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development.     

Interactive effects of UV, benzo[alpha] pyrene, and cadmium on DNA damage and repair in embryos of the grass shrimp Paleomonetes pugio

We examined the link between DNA strand breaks and hatching rates in grass shrimp, (Paleomonetes pugio), embryos exposed to 0.2 microM benzo[alpha] pyrene (BP), 5 microM cadmium (Cd) and 330 kJ/m(2) UV light, either alone or together. After exposure, embryos were transferred to clean seawater with or without 5 microM Cd. Hatching rates and DNA strand breaks (Comet Assay) were determined. DNA lesions caused by exposure to BP, UV light, or BP/cadmium were rapidly repaired and were not associated with any effects on hatching. Exposure to Cd after exposure to BP or UV did not affect embryological development or DNA repair. Exposure to BP/UV resulted in a high level of DNA lesions which were slowly repaired. Exposure to cadmium following BP/UV exposure inhibited hatching and DNA repair. Adducts formed during exposure to BP/UV exposure may be difficult to excise or may saturate the nucleotide excision repair system.     

DNA/RNA提取及处理方法对评价沉积物中纤毛虫分子多样性的影响

环境DNA(eDNA)技术结合高通量测序已广泛应用于评价微型生物多样性与群落构成。相较于eDNA,RNA在环境中易降解,环境RNA(eRNA)可更准确地反映群落近期生命活性状态。理论上,基于eRNA检获的生物多样性要低于eDNA检获的总体多样性。但前期已发表研究显示同一站点eDNA获得的多样性低于eRNA检获量,推测可能原因包括:1)样本量不同;2)RNA中存在DNA污染。为验证假设,本研究以陆架区2个站位沉积物中的纤毛虫为实验对象,系统性比较4种DNA/RNA提取方法:DNA直接提取(0.9 g沉积物),大样本量DNA直接提取(2 g), DNA洗脱法(2 g), RNA直接提取法(2g);以及3种RNA提取后的处理方法:无DNA酶反转录,含DNA酶反转录,先纯化RNA再反转录。研究结果表明,大样本量(2 g)DNA直接提取法所检获的可操作分类单元(OTUs)约为小样本量(0.9 g)的2倍。相同样本量下, DNA洗脱法检获的OTUs最多,而DNA直接提取检获的OTUs低于有/无DNA酶反转检获的数量,先纯化再反转录所获得OTUs最少。就群落构成而言, DNA洗脱法和RNA纯化可有效...     

Dietary transfer of fluoranthene from an estuarine oligochaete (Monopylephorus rubroniveus) to grass shrimp (Palaemonetes pugio): Influence of piperonyl butoxide

The objective of this study was to determine the potential for dietary transfer of sediment-associated fluoranthene from tubificid oligochaetes (Monopylephorus rubroniveus) to grass shrimp (Palaemonetes pugio). Grass shrimp, either in the presence or absence of sublethal waterborne concentrations of the metabolic inhibitor, piperonyl butoxide (PBO), were fed fluoranthene-dosed oligochaetes for 5-days. All grass shrimp bioaccumulated fluoranthene; however, bioaccumulation was 3X higher in the presence of PBO. Trophic transfer coefficients (TTCs) were 0.02 and 0.01 in the presence and absence of PBO, respectively. Following the 5-day accumulation period, shrimp in both treatments were allowed to depurate for 3 days. Depuration rates were significantly higher in PBO-exposed shrimp. These results demonstrated that sediment-associated fluoranthene can be transferred through the diet from oligochaetes to grass shrimp, and the presence of PBO enhanced fluoranthene bioaccumulation. However, the comparatively low TTCs suggest that biomagnification of fluoranthene in estuarine food webs is low.     

北极河流径流对北冰洋环流的影响

北极河流径流是北冰洋淡水的最大来源,其变化会对北冰洋中的诸多过程有重要影响。本文基于全球高分辨率海洋-海冰耦合模式的模拟结果,研究北冰洋温盐、海冰以及环流对北极河流径流的敏感性。通过对比有气候态北极河流径流输入的控制实验结果和径流完全关闭的敏感性实验结果,研究发现北极径流对北冰洋温度、盐度、海冰以及海洋环流等有显著的影响。关闭北极河流径流后,在河口附近的陆架上温度降低、盐度升高,且导致500 m深度处温度下降以及盐度升高;河口附近的陆架处,海冰密集度与海冰厚度增加。关闭北极河流径流也对北冰洋内的环流有影响:由于缺少来自欧亚大陆的北极径流的输入,穿极漂流与东格陵兰流流速减小且盐度增加;关闭北极径流导致近岸海表面高度降低,沿欧亚陆架的北冰洋边界流减弱,白令海入流增强。通过对比关闭北极径流实验与控制实验的温度和盐度剖面,发现关闭北极径流后大西洋层温度降低,各陆架海盐跃层的梯度减小,盐跃层厚度减小。     

枝管藻多糖对久效磷暴露水体中鱼类保护作用的研究

以金鱼(Carassius auratus)体内超氧化物歧化酶(Superoxide dismutase，SOD)活力、乙酰胆碱酯酶(Acetylcholinesteras，AChE)活力变化为指标，观察了枝管藻多糖对久效磷暴露的水体中鱼类生理功能的影响。结果表明：用枝管藻多糖灌胃鲫鱼15d，枝管藻多糖能显著降低久效磷对鱼类体内SOD活力的诱导和有效阻止久效磷对鱼类中枢神经系统AChE活性的抑制，具有拮抗久效磷农药对鱼类毒害的作用。     

Effects of contaminated sediments and sediment-exposed effluent water on an estuarine fish: Acute toxicity

The Elizabeth River is Virginia's most heavily populated, industrialized and contaminated subestuary. Its sediments contain the residues of wastes discharged for several hundred years. To examine some of the effects of sediment from a particularly noxious location, we chose the spot (Leiostomus xanthurus), a bottom-feeding sciaenid and naturally occurring spring-summer migrant of the river whose juveniles adapt readily to laboratory conditions. Spot from the Ware River, a nearby uncontaminated reference subestuary, were placed in two 380 liter (100 USgal), flow-through tanks (70 each). One tank contained Elizabeth River sediments contaminated with PAHs. The second tank contained uncontaminated sediment from the York River as a control. 13 spot each were placed in two aquaria that received the overflow from the sediment-containing tanks. Animals from the reference estuary were examined and processed to provide baseline information.Results obtained to date show the following: (1) spot experimentally exposed to contaminated sediment developed penetrating integumental lesions within 8 days after exposure began and later severe fin and gill erosion; (2) their hematocrits were significantly reduced and no weight gain occurred; (3) pancreatic and liver alterations were observed in some of the chemically stressed fish; (4) control fish exhibited no fin erosion or integumental lesions; (5) control fish showed no hematocrit or growth reduction; and (6) dead fish were first observed in the contaminated-sediment tank after 8 days while no control fish died. Clearly, one or more factors associated with Elizabeth River sediments and/or water closely associated with those sediments (probably the heavy concentrations of PAHs) are capable of causing serious injury, disease and death in experimental spot populations.     

Differences in the effects of mercury on predator avoidance in two populations of the grass shrimp Palaemonetes pugio

Adult Palaemonetes pugio were collected from two tidal creek systems, Piles Creek (PC), a mercury polluted estuary, and Big Sheepshead Creek (BSC), a relatively pristine creek. Adult killifish (Fundulus heteroclitus), a natural predator of P. pugio, were obtained from BSC. For each test, ten treated (0·01 mg/liter mercuric chloride (HgCl), or 0·01 mg/liter methylmercuric chloride (MeHg)), or control shrimp here introduced into a tank containing three fish. The time between capture of the first and second BSC HgCl treated shrimp was significantly faster (P < 0·05), as was the time between the first and second capture (P < 0·05) of MeHg treated BSC shrimp when compared with their respective controls. In addition, significantly more (P < 0·025) BSC HgCl treated shrimp were captured after 120 min. No significant difference existed between control and HgCl treated PC shrimp; however, significantly more PC MeHg treated shrimp were captured after 60 (P < 0·05) min when compared with their respective controls. These data suggest that PC shrimp, subjected to mercury in their natural environment, are more tolerant to the sublethal effects of both HgCl and MeHg. These data also suggest that behavioral studies can be very sensitive assays for determining the effects of sublethal concentrations of toxicants on populations of organisms.     

多环芳烃对鱼类生殖机能的影响

本文综述了近年来多环芳烃(含有两个苯环以上的有机化学污染物)对鱼类生殖机能影响的研究。重点介绍了多环芳烃对鱼类相关激素水平、卵黄蛋白原的生成以及生殖成功的影响。并对其可能的作用机制和途径进行了分析，提出了进一步研究的方向。     

丰年虫粉虾苗幼体饲料对日本对虾溞状幼体的影响

本文就丰年虫粉虾苗幼体饲料(OG)对日本对虾溞状幼体的影响进行试验初步得出，OG饲养效果优于日本车元饲料，从溞状幼体1期至糠虾幼体1期的转化率提高9.2％，且转化时间缩短了0.5d，幼体活力好.文中还就相关的问题进行了讨论.     

Effects of irradiance on excystment of tintinnids from marine sediments

The effects of irradiance on the excystment of tintinids from marine sediments were examined by incubating sediment samples in filtered seawater under various light levels. The total incidence of tintinnid excystment over five days was significantly less at low irradiance at and less than 2.5 E m^–2sec^–1 comparing to that at higher irradiance, at and more than 6.9 E m^–2sec^–1 (p<0.01), indicating that excystment of tintinnids is inhibited under low irradiance conditions. These results imply that water depth, disturbance of surface sediments and vertical mixing of water influence the excystment of tintinnids in coastal areas because these factors determine the light levels to which the tintinnid cysts are exposed.     

不同生物量的乳酸杆菌对对虾养殖池3种常见优势微藻的影响

在实验室条件下,分别把对虾养殖池常见优势种——微绿球藻（Nannochloropsis oculata）、隐藻（Cryptomonas erosa）和颤藻（Oscillatoria）与乳酸杆菌（Lactobacillusspp.）在对虾养殖水体中共同培养,研究不同生物量的乳酸杆菌对3种微藻的影响.实验分4组,乳酸杆菌分C1（10^3cells/cm^3）组、C2（10^4cells/cm^3）组、C3（10^5cells/cm^3）组、C4（10^6cells/cm^3）组四个浓度.结果表明：不同生物量的乳酸杆菌对不同微藻的影响有很大差异.C1（10^3cells/cm^3）乳酸杆菌对微绿球藻的生长没有明显的影响,对隐藻和颤藻生长有明显的抑制作用.C2（10^4cells/cm^3）乳酸杆菌对微绿球藻和隐藻生长有明显的促进作用,对颤藻生长有明显的抑制作用.C3（10^5cells/cm^3）乳酸杆菌对隐藻生长有明显的抑制作用,对颤藻的生长有明显的促进作用.C4（10^6cells/cm^3）乳酸杆菌对微绿球藻和颤藻生长有较明显的促进作用,对隐藻生长有微弱的抑制作用.无论是抑制作用还是促进作用,这种作用都随实验时间的延长而减弱.     

Copper bioavailability to marine bivalves and shrimp: Relationship to cupric ion activity

Studies were performed to determine the effects of dissolved substances present in natural seawater and sediment on the bioavailability of added Cu⁺². Whole clams Macoma inquinata and shrimp, Pandalus danae, were exposed to four concentrations of Cu in a flow-through seawater system. Bioaccumulation of Cu was reduced in shrimp, Pandalus danae, clams, M. inquinata, and excised clam gills, Protothaca staminea, exposed to an aged, compared with an unaged, Cu-seawater solution. This is thought to be due to slow complexation of the Cu by dissolved substances present in natural seawater. In a static system, with added sediment, more than 50% of the added Cu⁺² became bound to the organic fraction of the sediment and was unavailable to suspension feeding clams, Protothaca staminea. In contrast, deposit feeding clams, Macoma inquinata, placed in the sediment approximately doubled in Cu body burden within two months.Complexed Cu appears to be less bioavailable than ionic Cu and hence measurements of ionic and weakly complexed Cu by differential pulse anodic stripping voltametry provide a better prediction of bioavailable Cu than conventional measurements of total Cu-seawater concentrations.