Genetics of whitefish and vendace in England and Wales

Proportion of loci polymorphic ( P ) and mean heterozygosity per locus ( H _exp) were P = 0.130 and H _exp= 0.096 for C. albula from the English Lake District and P = 0.217 and H _exp= 0.046 for C. lavaretus from the English Lake District and Llyn Tegid, Wales in 1991–2. Significant deviation from the Hardy-Weinberg model was observed at the superoxide dismutase ( sSOD* ) locus in C. albula from Bassenthwaite Lake. This could have been due to chance, to the Wahlund effect or to selection. Genetic distances between the two species were consistent with their taxonomy and genetic differentiation was much greater for the C. lavaretus populations than for the two geographically close C. albula stocks. Llyn Tegid C. lavaretus showed unique alleles at two loci and conservation of fish in this lake is therefore of great importance. Red Tarn C. lavaretus differed most from other Lake District populations probably due to founder effects from early stocking events and/or from selection due to the high altitude of this lake.     

Impact Assessment of an Independent Agency for Animal Health in England

The applicability of a stochastic model was explored to assess the impact of a new independent agency for animal health in England in terms of the cost of animal disease outbreaks. The new agency was proposed to take responsibility for animal disease management in England. The stochastic model estimates the likelihood that the proposed new agency would face animal disease outbreaks of major and minor magnitude; and how many outbreaks of each magnitude, within its first 30 years of operation. Large variability in the potential total cost of the new agency was attributable to the possibility of an outbreak of an unknown major disease, although Bluetongue, Foot and Mouth Disease, and Avian Influenza were also influential. The results show that if the new agency reduces disease costs by even 0.5%, this could benefit society by an estimated £21 million per year. The stochastic approach offers a method for dealing with uncertainties in any continuing deliberations regarding the proposed new agency, resulting in a potential annual gain of £73 million ranging to an annual loss of £144 million.     

Endocrine Toxicants and Reproductive Success in Fish

There is compelling evidence on a global scale for compromised growth and reproduction, altered development, and abnormal behaviour in feral fish that can be correlated or in some cases causally linked with exposure to endocrine disrupting chemicals (EDCs). Attributing cause and effect relationships for EDCs is a specific challenge for studies with feral fish as many factors including food availability, disease, competition and loss of habitat also affect reproduction and development. Even in cases where there are physiological responses of fish exposed to EDCs (e.g., changes in reproductive hormone titres, vitellogenin levels), the utility of these measures in extrapolating to whole animal reproductive or developmental outcomes is often limited. Although fish differ from other vertebrates in certain aspects of their endocrinology, there is little evidence that fish are more sensitive to the effects of EDCs. Therefore, to address why endocrine disruption seems so widespread in fish, it is necessary to consider aspects of fish physiology and their environment that may increase their exposure to EDCs. Dependence on aquatic respiration, strategies for iono-osmotic regulation, and maternal transfer of contaminants to eggs creates additional avenues by which fish are exposed to EDCs. This paper provides an overview of responses observed in feral fish populations that have been attributed to EDCs and illustrates many of the factors that need consideration in evaluating the risks posed by these chemicals.     

Geography of Invasion in Mountain Streams: Consequences of Headwater Lake Fish Introductions

The introduction of fish into high-elevation lakes can provide a geographic and demographic boost to their invasion of stream networks, thereby further endangering the native stream fauna. Increasingly, remaining populations of native salmonids are concentrated in fragmented headwater refugia that are protected by physical or biological barriers from introduced fishes that originate in the pervasive source populations established at lower elevations. Although fish introduced near mainstem rivers frequently encounter obstacles to upstream dispersal, such as steep slopes or falls, we found that brook trout (Salvelinus fontinalis) dispersed downstream through channel slopes of 80% and 18-m-high falls. Thus, headwater lake stocking provides source populations that may be capable of invading most downstream habitats, including headwater refugia of native fishes. The extent of additional area invasible from lakes, beyond that invasible from downstream, depends on the geography of the stream network, particularly the density and distribution of headwater lakes and their location relative to barriers inhibiting upstream dispersal. In the thermal and trophic environments downstream of lakes, fish commonly grow faster and thus mature earlier and have higher fecundity-at-age than their counterparts in other high-elevation streams. The resulting higher rates of population growth facilitate invasion. Larger body sizes also potentially aid the fish in overcoming barriers to invasion. Trout introductions to high-elevation headwater lakes thus pose disproportionately large risks to native fishes—even when the place of introduction may appear to be spatially dissociated from populations of the native species. Mapping the potential invasible area can help to establish priorities in stocking and eradication efforts. Received 28 March 2000; accepted 9 February 2001.     

Immunotoxicity Biomarkers in Fish: Development,Validation and Application for Field Studies and Risk Assessment

Imunocompetence is usually monitored using a tiered approach that is based upon several parameters including immunopathology, immune function, and host resistance. Through the efforts of numerous investigations, well-characterized immune assays validated in rodents for their sensitivity and reproducibility in assessing xenobiotic-induced immunotoxicity are currently available. Recently, many of these same endpoints have been utilized in non-mammalian species as indicators to predict chemical-induced immunotoxicity. In this laboratory, immune assays that measure immunopathology, antibody-forming cell response to T-dependent antigens, lymphocyte proliferation, macrophage function, antioxidant activity, and host resistance against infectious bacteria have been employed successfully to assess metal-, pesticide-, aromatic hydrocarbon-, and mixture-induced immunotoxicity in laboratory-reared Japanese medaka (Oryzias latipes). These same assays have also proven successful in feral fish populations for predicting risk(s) associated with habitation in contaminated aquatic environments. For example, smallmouth bass (Micropterus dolomieu) collected from a polychlorinated biphenyl-contaminated site had reduced phagocyte function, oxyradical production, and antioxidant levels (compared to reference fish), while circulating leukocyte profiles and lymphocyte proliferation by splenic T-cells were altered in organochlorine-exposed walleye (Stizostedium vitreum vitreum). Results of the aforementioned studies demonstrate that immune assays developed and validated in a laboratory fish model can be successfully applied to feral fish populations to predict the toxicological hazards associated with exposure to immunomodulating aquatic pollutants.     

Predictive Assessment of Fish Health and Fish Kills in the Neuse River Estuary Using Elicited Expert Judgment

Declining fish health and the occurrence of large fish kills are some of the more publicly meaningful indicators of water quality in the impaired Neuse River Estuary, North Carolina. It is generally believed that such problems are caused by the widespread depletion of dissolved oxygen—an indirect result of anthropogenic nutrient pollution. However, the development of scientific simulation models to predict how improvements in oxygen conditions will improve the health of fish and reduce the frequency of fish kills has proven elusive. As a pragmatic solution to this problem, the expert opinion of estuarine fisheries scientists in possession of relevant data and experience was elicited. The relations between joint and conditional probabilities were exploited to translate quantities that are normally hard to assess into quantities that can be drawn more directly from the experiential knowledge of the experts. A combined model of expert opinion was constructed as an influence diagram, and Monte Carlo simulation was used to generate predictions of fish health and fish kills in the Neuse River Estuary under current and improved oxygen conditions. Full model results are expressed as probability distributions, capturing the effects of natural variability and knowledge uncertainty—both contributors to total ecological risk.     

An Ecological Risk Assessment of Formaldehyde

A multi-tiered environmental risk assessment of formaldehyde determined the possibility of harmful effects on organisms in certain environmental compartments in Canada. A review of the relevant information indicates that biota are exposed to formaldehyde primarily in air and, to a lesser extent, in water. Worst-case scenarios predict that the estimated exposure values likely to be encountered in Canada for water and air are not expected to exceed estimated no-effects values. Therefore, the environmental risks associated with concentrations of formaldehyde likely to be found in Canada are low.     

Seasonal Variation of Boron and Fluoride in Tilapia nilotica from an Egyptian Fish Farm in Relation to Human Health Hazard Assessment

This study evaluated the seasonal accumulation of boron and fluoride in different tissues of a common edible fish, Tilapia nilotica, from an Egyptian fish farm as well as their hazard to human health. Among all the determined fish tissues, brain, liver, and bone were the ones that accumulated the highest boron and fluoride contents. Interestingly, flesh tissue showed the lowest boron and fluoride concentrations (0.30 ± 0.06 and 2.50 ± 1.57 μg/g, respectively). Statistical analyses using Pearson correlation matrix and multiple regression procedures indicated that boron accumulation was highest amongst flesh, liver, brain, and bone tissues. Additionally, fluoride content in water affects its abundance in the different fish tissues: flesh, gills, bone, and skin. Human hazard assessment of fluoride and boron from water, sediment, and fish flesh tissue was studied using calculations that considered chronic daily intake from water, sediment, and fish; chronic exposure from dermal contact and ingestion of water; and fish as well as a single acute human dose. These calculations indicated that the consumption of Tilapia nilotica is still safe as regards boron intake, but for fluoride, it may pose a hazard to human health in the long term.     

An Ecological Risk Assessment of Phenol in the Aquatic Environment

A probabilistic ecological risk assessment of phenol was undertaken to determine the risks posed to biota as a result of phenol release to the Canadian environment. A three-tiered approach was used to estimate risks, with progressively more realistic assumptions being applied at each tier. In Canada, the major sources of phenol are municipal wastewater treatment plants, pulp, paper and wood products mills, steel and metal products facilities and refineries. Thus, the highest exposures will occur in receiving waters near these point sources, primarily due to the short half-life of phenol in the aquatic environment. Sensitive aquatic organisms include salmonids (e.g., rainbow trout Oncorhynchus mykiss) and amphibians (e.g., leopard frog Rana pipiens). The results of the risk assessment indicate that species are exposed to elevated levels of phenol near point sources, but these levels represent only a minor risk to aquatic biota.     

Fish as Bioreactors: Transgene Expression of Human Coagulation Factor VII in Fish Embryos

A plasmid containing human coagulation factor VII (hFVII) complementary DNA regulated by a cytomegalovirus promoter was microinjected into fertilized eggs of zebrafish, African catfish, and tilapia. The active form of hFVll was detected in the fish embryos by various assays. This positive expression of human therapeutic protein in fish embryos demonstrates the possibility of exploitation of transgenic fish as bioreactors.     

Overview of Fish Consumption Rates in the United States

Contaminants that accumulate in fish may pose health risks and have raised concerns among consumers. Contaminated finfish and shellfish are possible routes of human exposure to toxic chemicals. Fish advisories are established to protect local populations from the consumption of contaminated commercial and non-commercially caught fish. Children, women of childbearing age, and subsistence fishermen or other highly exposed individuals who for socioeconomic or cultural reasons consume more fish than the general population are among the populations of concern from the ingestion of contaminated fish. Estimating exposure to a toxic chemical among fish-consuming populations requires knowledge about intake rates of fish and shellfish. Data on fish consumption rates come from various sources, including national, state, and local government studies. Although these data have their limitations, they serve as a source for deriving fish consumption rates that may be used by exposure assessors. Data on specific populations of concern are critical. Studies presented here show that ethnicity, age, and geographical region play an important role in fishing behavior and consumption. Results from studies on Native American populations show that this ethnic group eats fish at a higher rate than recreational anglers. This article summarizes data on fish consumption for various populations and provides a framework for evaluating data from these studies for exposure assessment applications.     

Cloning of Fish Enzymes and Other Fish Protein Genes

ABSTRACT:?

Fish metabolism needs special enzymes that have maximum activity at very different conditions than their mammalian counterparts. Due to the differences in activity, these enzymes, especially cold-adapted proteases, could be used advantageously for the production of some foods. In addition to the enzymes, this review describes some other unique fish polypeptides such as antifreeze proteins, fluorescent proteins, antitumor peptides, antibiotics, and hormones, that have already been cloned and used in food processing, genetic engineering, medicine, and aquaculture. Recombinant DNA technology, which allows these biological molecules to be cloned and overexpressed in microorganisms is also described, highlighting innovative applications. The expected impact of cloning fish proteins in different fields of technology is discussed.     

Assessment of pollution impact on aquatic microbial communities based on DNA hybridization and protozoan identification: preliminary method development and comparison

Common methods of assessing the biological impact of point source discharge involve a census of organisms above and below the discharge. The identification and enumeration of organisms necessary for this approach can be time consuming and costly. When microbial communities are used, identification and enumeration are often impossible because the majority of species are identifiable only when cultured and most native species cannot be cultured. As such, little is known about the response of nonculturable aquatic microbial communities to anthropogenic changes. We isolated aquatic microbial DNA from colonized artificial substrates in two streams receiving industrial waste. DNA was isolated from the microbial communities upstream and downstream of the discharges and the similarity of these communities were compared by DNA-DNA hybridization. These novel estimates of impact were compared to more conventional estimates based on a component of the microbial communities that could be readily identified, the protozoans. Protozoan species were identified and similarity between upstream and downstream stations was assessed using Jaccard's similarity index.In the Roanoke River, protozoan species richness was significantly lower at the downstream station. Both Jaccard's coefficients and DNA hybridizations indicated that upstream communities were more similar to each other than with the downstream site. However, these differences were not significant. Estimates of community similarity from Jaccard's coefficients and DNA hybridizations were not correlated. In Peak Creek, protozoan species richness was significantly lower at the downstream station. Jaccard's coefficients and DNA hybridizations were not significantly higher within upstream stations than between upstream and downstream stations. The two similarity measures were not correlated. Problems in this preliminary study included small sample sizes and highly variable background on hybridization membranes resulting from the use of nonradioactive DNA probe label and detection methods. Alternative approaches using radioisotopes or COT curves may be more viable means of making molecular methods a useful tool in impact assessment.     

Cervical screening in England and Wales: its effect has been underestimated

Opinions about cervical screening in the UK tend to follow one of two negative lines of thought. The first is that cervical cancer is a rare disease, and too much time and effort are spent on screening. The second is that it has been relatively ineffective, since incidence of invasive carcinoma did not fall until the NHS Cervical Screening Programme (NHSCSP) was introduced in 1988, although it fell by 40% since then. This paper presents publicly available data to demonstrate that neither of these views is true. Registrations of invasive carcinoma of the uterine cervix and carcinoma in situ in England and Wales between 1971 and 1996 show that a substantially increased risk of disease in women born since 1940 has been reversed, almost certainly by greatly improved screening. Cervical carcinoma is now a rare disease because most cases are prevented before they become invasive, mostly by screening young women, aged 20-40, before the decade of life when symptomatic cervical carcinoma most frequently presents.     

Effect of Fish Oil and Coconut Oil on Antioxidant Defence System and Lipid Peroxidation in Rat Liver

Diets high in fish oil containing polyunsaturated fatty acids of the n-3 family. have been suggested to decrease the risk of cardiovascular disease. However these lipids are highly susceptible to oxidative deterioration. In order to investigate the influence of n-3 fatty acids on oxidative status, the effect of feeding rats with fish oil or cocunut oil diets was studied by measuring different parameters related to an oxidative free radical challenge. Synthetic diets containing 15% (w/v) fish oil or coconut oil were used to feed growing rats for 4 weeks. As compared to control diet, the fish oil containing diet produced a significant decrease of cholesterol and triglyceride concentration in serum. however there was a significant increase in lipid peroxidation products. In addition, in fish oil fed animals, there was also a decrease in vitamin E and A concentration. Furthermore, the rate of lipid peroxidation in isolated microsomes was three fold higher in rats fed fish oil as compared to rats with coconut oil diet. No significant differences between the two experimental groups were observed in superoxide dismutase (SOD) and phospholipid hydroperoxide glutathione peroxidase (PHGPX) activities. However, there was a decrease in glutathione peroxidase (GPX) activity. These results suggest that fish oil feeding at an amount compatible with human diet, although decreasing plasma lipids, actually challenge the antioxidant defence system, thus increasing the susceptibility of tissues to free radical oxidative damage.     

17β-雌二醇对剑尾鱼卵黄蛋白原的诱导研究

目的研究17β-雌二醇(E2)暴露对雄性剑尾鱼(Xiphophorus helleri)卵黄蛋白原(vitellogenin,Vtg)诱导作用作为环境风险评价(ERA)的有效生物学标记的可行性。方法以E2诱导的剑尾鱼雄性个体的整体匀浆液为材料,采用Sephacryl S-300凝胶过滤层析柱和QSepharose阴离子交换柱从剑尾鱼体内提纯Vtg。结果确定了被纯化的剑尾鱼Vtg在4%~7.5%Native PAGE电泳中相对分子质量为540×103。4%~7.5%Native PAGE电泳后的凝胶分别利用苏丹黑B进行脂蛋白染色、高碘酸-Schiff试剂进行糖蛋白染色和甲基绿进行磷蛋白染色,表明剑尾鱼Vtg是一种富含糖、脂、磷的蛋白。结论表明雄性剑尾鱼卵黄蛋白原的诱导变化可作为环境风险评价(ERA)的有效生物学标记。     

Exposure Assessment of Pharmaceuticals and Their Metabolites in the Aquatic Environment: Application to the French Situation and Preliminary Prioritization

Low levels of pharmaceuticals have been detected in many countries in surface waters. As a wide range of pharmaceuticals can reach aquatic environments, a selection of molecules to survey is the first step before implementing a monitoring program. We used a simple equation to calculate Predicted Environmental Concentrations (PECs), adapted from the European Medicine Agency model used for the Environmental Risk Assessment (ERA) of human pharmaceutical. Excretion fractions for pharmaceuticals were determined for 76 compounds. Using year 2004 French drug consumption data, we determined aquatic PECs for 112 parent molecules and several metabolites. Considering excretion fractions of pharmaceuticals can lead to drastically reduce predicted concentrations reaching the aquatic environment and help to target environmentally relevant pharmaceuticals and metabolites. Calculated PECs using the described methodology are consistent with French field measurements. The simple model for calculating PECs can be used as a valuable estimation of the exposure. Risk quotient ratios were also calculated. Due to the lack of ecotoxicological data, the use of PEC/PNEC ratios is not enough informative to prioritize pharmaceuticals likely to pose a risk for surface waters. Alternative ways to prioritize risk to pharmaceuticals, combining PEC, pharmacological, and ecotoxicological data available from the literature, should be implemented.     

Ecological aspects of water quality regulation in England and Wales

The paper describes the regulatory functions of a new body set up in England and Wales for the management of water pollution, the National Rivers Authority. It outlines proposals for a new water quality classification scheme incorporating biological monitoring as an integral part, and describes other areas of pollution control where biology could be used with advantage. The derivation of statutory water quality objectives as a new concept in the management of natural waters is described, together with an indication of some of the legal mechanisms available to the NRA to ensure that the objectives are met.     

Issues in Exposure and Dose Assessment for Epidemiology and Risk Assessment

Epidemiologic studies have been effective in identifying human environmental and occupational hazards. However, most epidemiologic data has been difficult to use in quantitative risk assessments because of the vague specification of exposure and dose. Toxicologic animal studies have used applied doses (quantities administered, or exposures with fixed duration) and well characterized end points to determine effects. However, direct use of animal data in human risk assessment has been limited by uncertainties in the extrapolation. The applied dose paradigm of toxicology is not suited for cross species extrapolation, nor for use in epidemiology as a dose metric because of the complexity of human exposures. Physiologically based pharmacokinetic (PBPK) modeling can estimate the time course of tissue concentrations in humans, given an exposure-time profile, and it has been used for extrapolating findings from animals to humans. It is proposed that human PBPK modeling can be used in appropriately designed epidemiologic studies to estimate tissue concentrations. Secondly, tissue time courses can be used to form dose metrics based on the type and time course of adverse effects. These dose metrics will strengthen the determination of epidemiologic dose-response relationships by reducing misclassification. Findings from this approach can be readily integrated into quantitative risk assessment.