Distribution by Scientific Domains

Terms modified by Gills

  • gill arch
  • gill cell
  • gill disease
  • gill epithelium
  • gill filament
  • gill lamella
  • gill na+
  • gill net
  • gill slit
  • gill tissue

  • Selected Abstracts

    Mountain resort planning and development in an era of globalization by Thomas A. Clark, Alison Gill and Rudi Hartmann (eds), Cognizant Communication Corporation, New York.

    No. of pages: xi + 348.
    No abstract is available for this article. [source]

    Rethinking Social Security in Latin America

    Indermit Gill
    In the past decade, many Latin American governments have radically restructured their old age income security systems, following the lead of Chile, which undertook its major pension reform in 1981. The defining characteristic of the reforms has been a shift in the basis of public pensions from social to individual responsibility: instead of the widely used system that "collectivized" or pooled the risk of being without the capacity to earn while aged, numerous countries in the region have adopted a system that relies on individual savings accounts. The reforms have maintained a role for a modified version of public pooling; this combination of individual and social savings to finance pensions is known as the "multipillar" approach. This article is based on a report prepared for the Office of the Chief Economist of the Latin America and Caribbean Region of the World Bank (Gill, Packard and Yermo, 2004).1 The report recognizes that the system of individual accounts, the essential aspect of the reform, has been a necessary and positive development, and one that is consistent with the economics of insurance and social welfare objectives. Beyond this recognition, however, the results of reform are much more complex. Each country has implemented its own version of the multipillar system. The article therefore draws on country evidence in order to determine: How has the new approach to public pensions in Latin America fared? In particular, have the changes left workers and their families in reform countries better off? The first section provides a brief description of the reforms. The second discusses the main macroeconomic concerns and effects. The third describes the impact on coverage levels, and other social welfare implications. The fourth evaluates the stagnation of coverage levels and presents various possible explanations. The fifth makes specific proposals to improve the multipillar pension system in Latin America. The last section concludes. [source]

    An evaluation of the radial part of numerical integration commonly used in DFT

    Aisha El-Sherbiny
    Abstract Recently, Gill and Chien introduced a new radial quadrature for multiexponential integrands (MultiExp grid) to deal with the radial part of the numerical integration. In this article, the MultiExp grid is studied and used to integrate the charge density. The MultiExp grid, along with an optimal pruning scheme, performed very well both in terms of accuracy and efficiency compared to other radial mappings commonly used in Density Functional Theory. © 2004 Wiley Periodicals, Inc. J Comput Chem 11: 1378,1384, 2004 [source]

    Functional morphology of the sonic apparatus in the fawn cusk-eel Lepophidium profundorum (Gill, 1863)

    JOURNAL OF MORPHOLOGY, Issue 11 2007
    Michael L. Fine
    Abstract Recent reports of high frequency sound production by cusk-eels cannot be explained adequately by known mechanisms, i.e., a forced response driven by fast sonic muscles on the swimbladder. Time to complete a contraction-relaxation cycle places a ceiling on frequency and is unlikely to explain sounds with dominant frequencies above 1 kHz. We investigated sonic morphology in the fawn cusk-eel Lepophidium profundorum to determine morphology potentially associated with high frequency sound production and quantified development and sexual dimorphism of sonic structures. Unlike other sonic systems in fishes in which muscle relaxation is caused by internal pressure or swimbladder elasticity, this system utilizes antagonistic pairs of muscles: ventral and intermediate muscles pull the winglike process and swimbladder forward and pivot the neural arch (neural rocker) above the first vertebra backward. This action stretches a fenestra in the swimbladder wall and imparts strain energy to epineural ribs, tendons and ligaments connected to the anterior swimbladder. Relatively short antagonistic dorsal and dorsomedial muscles pull on the neural rocker, releasing strain energy, and use a lever advantage to restore the winglike process and swimbladder to their resting position. Sonic components grow isometrically and are typically larger in males although the tiny intermediate muscles are larger in females. Although external morphology is relatively conservative in ophidiids, sonic morphology is extremely variable within the family. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source]

    Discussion on the paper by Barndorff-Nielsen, Gill and Jupp

    Article first published online: 28 OCT 200

    Men of Uncertainty: The Social Organization of Day Laborers in Contemporary Japan.

    Kalman Applbaum
    Men of Uncertainty: The Social Organization of Day Laborers in Contemporary Japan. Tom Gill. Albany: State University of New York Press, 2001. 263 pp. [source]

    Some alternatives in the statistical analysis of sickness absence

    Albert Navarro
    Abstract Purpose Sickness absence (SA) is a commonly used outcome in occupational health cohort studies. Without the use of statistical techniques that take into account that SA is a recurrent event, the probability of obtaining biased estimates of the effects related to SA is very high. The objective of this article is to examine the application of marginal models, comparing them to count-based models, when the outcome of interest is SA. Methods By re-sampling the data of a reference study, 1,000 samples of 1,200 individuals were generated. In each of these samples, the coefficients of two factors were estimated by fitting various models: Poisson, Negative Binomial, standard Cox model for a first occurrence, Andersen,Gill and Prentice,Williams,Peterson. Results In general, differences among the models are observed in the estimates of variances and coefficients, as well as in their distribution. Specifically, the Poisson model estimates the greatest effect for both coefficients (IRR,=,1.17 and IRR,=,1.60), and the Prentice,Williams,Peterson the least effect (HR,=,1.01 and HR,=,1.26). Conclusions Whenever possible, the instantaneous form of analysis should be used for occurrences of a recurrent event. Collection of study data should be organized in order to permit recording of the most complete information possible, particularly regarding event occurrences. This should allow the presence of within-individual heterogeneity and/or occurrence dependency to be studied, and would further permit the most appropriate model to be chosen. When there is occurrence dependence, the choice of a model using the specific baseline hazard seems to be appropriate. Am. J. Ind. Med. 52:811,816, 2009. © 2009 Wiley-Liss, Inc. [source]

    Proportional Intensity Models Robustness with Overhaul Intervals

    Shwu-Tzy Jiang
    Abstract The class of semi-parametric proportional intensity (PI) models applies to recurrent failure event modeling for a repairable system with explanatory variables (covariates). Certain repairable systems (e.g. aircraft and electrical power generating plants) experience a substantial period of downtime due to performing maintenance (i.e. major overhaul) at scheduled intervals or following a major failure. Other systems (e.g. emergency power units) experience extended periods of non-operating dormancy. These discontinuities in observation time have potential effects on the accuracy of estimation for covariate effects, particularly where calendar time is the life metric. This paper examines the robustness of two PI methods (Prentice,Williams,Peterson gap time (PWP-GT) and Andersen,Gill (AG)) as a function of the overhaul or dormancy duration. The PWP-GT model proves to perform well for sample size of 60 (30 per level of a class covariate), constant or moderately decreasing/increasing rate of occurrence of failures, and relative overhaul (dormancy) durations less than half of the immediately preceding interval between failures. The AG model performs consistently well for a small sample size of 20 (10 per level of a class covariate) for homogeneous Poisson processes, regardless of the relative overhaul (dormancy) duration. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A Gill,Matsuno-type mechanism explains the tropical Atlantic influence on African and Indian monsoon rainfall

    F. Kucharski
    Abstract Recent studies using coupled atmosphere,ocean models have shown that the tropical Atlantic has a significant impact on the Indian monsoon. In this article, the observational basis for this teleconnection is examined and the physical mechanism responsible for bridging sea-surface temperatures (SSTs) in the Atlantic and precipitation over India is investigated with idealized atmospheric general circulation model (AGCM) experiments in which constant SST anomalies are prescribed and ,switched on' in the tropical Atlantic region. A simple Gill,Matsuno-type quadrupole response is proposed to explain the teleconnection between the tropical Atlantic and the Indian basin, with an enforcement of the eastward response likely due to nonlinear interactions with the mean monsoon circulation. The simplicity of this mechanism suggests the reproducibility of this result with a broad range of AGCMs. Copyright © 2009 Royal Meteorological Society [source]

    Relationships between fish and supralittoral vegetation in nearshore marine habitats

    Tamara N. Romanuk
    Abstract 1.This study was conducted to determine whether there were significant differences in the species richness and community composition of fish assemblages in coastal nearshore habitats with differing compositions of supralittoral vegetation. 2.We sampled fish assemblages and conducted supralittoral vegetation surveys at 27 beaches on the west coast of Vancouver Island, British Columbia. Thirteen of the beaches had supralittoral vegetation characteristic of old-growth coastal forests and 14 had been previously subjected to logging or other disturbances. 3.Physical features (e.g. substrate, salinity, etc.) were recorded at each beach to determine whether there were significant associations between supralittoral vegetation and beach characteristics as well as between beach characteristics and fish assemblages. 4.Across all 27 beaches, 1832 individuals of 31 species of nearshore fish were collected, primarily juvenile cottids and salmonids. Mean species richness did not differ between beaches with old-growth versus secondary-growth supralittoral vegetation; however, a higher cumulative number of species was found at beaches with old-growth supralittoral vegetation. 5.Canonical Correspondence Analysis (CCA) showed that beach characteristics and supralittoral vegetation were not significantly associated. Separate CCA for fish associations with beach characteristics and fish associations with supralittoral vegetation explained ,55% of the variance in fish assemblage composition, suggesting that fish assemblage composition is significantly affected by substrate, submerged vegetation, and physico-chemical conditions as well as by the community composition of vegetation in adjacent supralittoral habitats. 6.Specifically, we found associations between supralittoral vegetation and penpoint gunnels (Apodichthys flavidus Girard), tidepool sculpins (Oligocottus maculosus Girard), Pacific staghorn sculpins (Leptocottus armatus Girard), arrow gobies (Clevelandia ios Jordan and Gilbert), shiner perch (Cymatogaster aggregata Gibbons) and kelp perch (Brachyistius frenatus Gill). Juvenile chum (Oncorhynchus keta Walbaum) and coho (Oncorhynchus kisutch Walbaum) salmon were strongly associated with supralittoral vegetation characteristic of mature coastal forests such as mosses and western red cedar (Thuja plicata) suggesting that some nearshore fish species may be affected by processes originating in terrestrial ecosystems. 7.Our results suggest that some nearshore fish species may be affected by removal of supralittoral vegetation. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    BOOK REVIEWS: Accountants' Truth: Knowledge and Ethics in the Financial World by,Matthew Gill

    David Gilchrist
    No abstract is available for this article. [source]

    Adding magnesium to the silver-gill binding model for rainbow trout (Oncorhynchus mykiss)

    Melissa L. Schwartz
    Abstract Rainbow trout (Oncorhynchus mykiss; 2,17 g) were exposed to approximately 0.1 ,M silver as AgNO3 for 3 to 4 h in synthetic, ion-poor water (20 ,M Ca, 100 ,M Na, 150 ,M Cl, pH 7) to which was added Mg, Ca, or thiosulfate (S2O3). Gills were extracted and assayed for Ag using graphite furnace atomic absorption spectrophotometry. Up to 210 mM Mg (four fold the concentration of Mg in seawater) did not reduce accumulation of Ag by trout gills. The conditional equilibrium stability constant (K) for Mg at silver-binding sites on the gills was calculated to be log KMg-gillAg = 3.0, or approximately half-as-strong binding as for Ca at these sites. The inclusion of the Mg-gill stability constant into the original Ag-gill binding model increases the flexibility of the model, although the competitive effects of Mg are only important in sodium-poor systems. [source]

    Structure, function and evolution of the gas exchangers: comparative perspectives

    JOURNAL OF ANATOMY, Issue 4 2002
    J. N. Maina
    Abstract Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that ,necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost,benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural,functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices , water or air , within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water,air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. [source]

    Ultrastructural Characterization of Gills in Juveniles of the Argentinian Silverside, Odontesthes bonariensis (Valenciennes, 1835) (Teleostei: Atheriniformes)

    F. A. Vigliano
    Summary An ultrastructural study was performed on the gills of juvenile Argentinian silverside, Odontesthes bonariensis. The gills are composed of two sets of four holobranchs and, in turn, each holobranch consists of a gill arch and two rows of caudolaterally projecting branchial filaments. From the dorsal and ventral surfaces of each filament, branchial lamellae radiate out as foldings of the epithelial layer. Gill rakers are present on each of the gill arches, on the anteromedial side of the arch opposite to the filaments. Gill rakers, gill arches and branchial filaments are covered by a stratified epithelium, whereas branchial lamellae essentially consist of a thin epithelial envelope containing capillaries. In the stratified epithelium, mucous cells, rodlet cells, granular cells, pavement epithelial cells and mitochondria-rich cells are identified. The thin epithelium that lines the lamellae comprises two cell types, outer and inner epithelial cells, and the capillary walls on the inside of the epithelial envelope are defined by pillar cells. The ultrastructure of all these cell types is described and our findings are discussed in light of the existing data on fish gill morphology. In the gills of juvenile Argentinian silverside is of particular interest the characteristics showed by mitochondria-rich cells, such as their arrangement in clusters of 2,3 cells and their small and depressed surface in contact with the aquatic milieu, features which strongly resemble those of euryhaline species. [source]

    P56 Occupational protein contact dermatitis from shiitake mushrooms

    CONTACT DERMATITIS, Issue 3 2004
    Renata Kaminska
    Case report:, A 54-year-old woman, with no family or personal history of atopy, developed skin symptoms and cough after she had been cultivating shiitake mushrooms for 12 months. The patient reported dermatitis on the backs of her hands, fingers and on her wrists, after 1 or 2 days of being in contact with shiitake mushrooms. The skin lesions and cough disappeared entirely during the holidays. Result: Prick tests to common inhalant allergens, molds and flours were negative, with the exception of D. farinae (3 mm). The prick-to-prick test was positive for shiitake gill (3 mm), shiitake stalk (3 mm) and dry shiitake (8 mm ps). The histamine wheal was 5,7 mm. Control prick tests with shiitake on 5 nonexposed subjects were negative. An open test was performed with shiitake on the flexor side of the upper arm. Within 20 minutes a positive reaction appeared comprising two wheals and flare reactions. Patch test with shiitake gave a strong toxic reaction in 2 days, which continued to diminish on days 3 and 4. Conclusion: Contact urticaria is the clinical skin symptom of immediate allergy, but repeated exposure may lead to protein contact dermatitis. However, our patient has not had urticaria symptoms from shiitake, although the prick-to-prick and open tests were positive. To our knowledge, this is the first report of protein contact dermatitis from shiitake in a patient with a positive immediate skin reaction and negative patch test result. [source]

    Developmental changes in the modulation of respiratory rhythm generation by extracellular K+ in the isolated bullfrog brainstem

    Rachel E. Winmill
    Abstract This study tested the hypothesis that voltage-dependent, respiratory-related activity in vitro, inferred from changes in [K+]o, changes during development in the amphibian brainstem. Respiratory-related neural activity was recorded from cranial nerve roots in isolated brainstem,spinal cord preparations from 7 premetamorphic tadpoles and 10 adults. Changes in fictive gill/lung activity in tadpoles and buccal/lung activity in adults were examined during superfusion with artificial CSF (aCSF) with [K+]o ranging from 1 to 12 mM (4 mM control). In tadpoles, both fictive gill burst frequency (fgill) and lung burst frequency (flung) were significantly dependent upon [K+]o (r2 > 0.75; p < 0.001) from 1 to 10 mM K+, and there was a strong correlation between fgill and flung (r2 = 0.65; p < 0.001). When [K+]o was raised to 12 mM, there was a reversible abolition of fictive breathing. In adults, fictive buccal frequency (fbuccal), was significantly dependent on [K+]o (r2 = 0.47; p < 0.001), but [K+]o had no effect on flung (p > 0.2), and there was no significant correlation between fbuccal and flung. These data suggest that the neural networks driving gill and lung burst activity in tadpoles may be strongly voltage modulated. In adults, buccal activity, the proposed remnant of gill ventilation in adults, also appears to be voltage dependent, but is not correlated with lung burst activity. These results suggest that lung burst activity in amphibians may shift from a "voltage-dependent" state to a "voltage-independent" state during development. This is consistent with the hypothesis that the fundamental mechanisms generating respiratory rhythm in the amphibian brainstem change during development. We hypothesize that lung respiratory rhythm generation in amphibians undergoes a developmental change from a pacemaker to network-driven process. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 278,287, 2003 [source]

    Phylogenetic comparison of spicule networks in cryptobranchiate dorid nudibranchs (Gastropoda, Euthyneura, Nudibranchia, Doridina)

    ACTA ZOOLOGICA, Issue 4 2008
    Brian K. Penney
    Abstract Many dorid nudibranchs possess large numbers of calcareous spicules in their mantle, gill, rhinophores and foot. However, the arrangements of these structures and their differences among taxa are poorly known. Spicule networks were stained with Alizarin red and compared among 12 species of cryptobranchiate dorid nudibranchs and four outgroups. Three general types of networks were found: a cobweb-like, unbraced framework of one or few spicules per side; a ramifying system of thick, spiculated tracts; and a lattice-like arrangement of distinct radial and circumferential tracts. The Discodorididae species investigated shared a cobweb-like network and papillae supported by a ring of spicules, while the Porostomata showed consistent characters leading to a lattice-like network with larger spicules in the central notum. The Dorididae studied were not cohesive, but each species shared characters with the aforementioned groups. Therefore, spicule network form may provide new characters to help resolve the phylogeny of Doridina. [source]

    Evaluation of river water genotoxicity using the piscine micronucleus test

    Serap Ergene
    Abstract The Berdan River, which empties into the Mediterranean Sea on the east coast of Turkey, receives discharges of industrial and municipal waste. In the present study, the in vivo piscine micronucleus (MN) test was used to evaluate the genotoxicity of water samples collected from different locations along the Berdan River. Nile tilapia (Oreochromis niloticus) were exposed in the laboratory for 2, 4, and 6 days, and micronuclei were evaluated in peripheral blood erythrocytes, gill cells, and caudal fin epithelial cells. A single dose of 5 mg/L cyclophosphamide was used as a positive control. In addition to micronuclei, nuclear abnormalities (NAs), such as binucleated cells and blebbed, notched, and lobed nuclei, were assessed in the erythrocytes, and chemical analyses were carried out to determine the amount of heavy metals in the water samples. MN and NA frequencies were significantly elevated (up to 2- to 3-fold) in fish exposed to river water samples taken downstream of potential discharges, and the elevated responses in gill and fin cells were related to the concentration of heavy metals in the water. MN frequencies (expressed as micronucleated cells/1,000 cells), in both treated and untreated fish, were greatest in gill cells (range: 0.80,3.70), and generally lower in erythrocytes (range: 0.50,2.80), and fin cells (range: 0.45,1.70). The results of this study indicate that the Berdan River is contaminated with genotoxic pollutants and that the genotoxicity is related to the discharge of wastes into the river water. Environ. Mol. Mutagen., 2007. © 2007 Wiley-Liss, Inc. [source]

    Molecular cloning of CYP1A gene and its expression by benzo(a)pyrene from goldfish (Carassius auratus)

    Seung-Min Oh
    Abstract We cloned and sequenced the cytochrome P450 1A (CYP1A) gene from goldfish (Carassius auratus). It has a 1581 bp open reading frame that encodes a 526 amino acid protein with a theoretical molecular weight of 59.02 kDa. The CYP1A amino acid sequence clusters in a monophyletic group with other fish CYP1As, and more closely related to zebrafish CYP1A (91% identity) than to other fish CYP1As. Exposure to benzo(a)pyrene (BaP) by intraperitoneal injection increased biliary BaP metabolites and liver CYP1A gene expression. BaP exposure also increased CYP1A gene expression in extrahepatic organs, including intestine, and gill, which are sensitive to aqueous and dietary exposure to Arylhydrocarbon receptor (AhR) agonists. Therefore, goldfish CYP1A identified in this study offers basic information for further research related to biomarker use of CYP1A of goldfish. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source]

    Levels of transaminases, alkaline phosphatase, and protein in tissues of Clarias gariepienus fingerlings exposed to sublethal concentrations of cadmium chloride

    Babu Velmurugan
    Abstract The freshwater fish, Clarias gariepienus fingerlings, were exposed to sublethal concentrations (1.7 and 3.4 mg/L) of cadmium chloride for 12 days. Aspartate aminotransferase (AAT), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total protein levels were assayed in the gill, brain, and muscle of the fish at regular intervals of 6 and 12 days. The activities of AAT, ALT, and ALP of the treated fishes increased significantly in all the tissues compared with the control fish. Protein level in all the tissues showed a significant decrease in comparison to unexposed controls throughout the experimental periods. These results revealed that cadmium chloride effects the intermediary metabolism of C. gariepienus fingerlings and that the assayed enzymes can work as good biomarkers of contamination. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source]

    Cadmium tolerance in the Nile tilapia (Oreochromis niloticus) following acute exposure: Assessment of some ionoregulatory parameters

    Sofia Garcia-Santos
    Abstract The Nile tilapia (Oreochromis niloticus) can tolerate very high levels of waterborne cadmium. It has one of the highest 96 h LC50 recorded for a freshwater teleost fish (14.8 mg/L Cd; hardness 50 mg/L CaCO3). Cadmium is known to perturb ion balance in teleost fishes. However, in an acute time course experiment, plasma Na+ concentrations were unaffected, and plasma Ca2+ values only decreased after 96 h exposure in a dose-independent manner. Branchial Na+/K+ -ATPase activity and ,-subunit protein level expression in crude gill homogenates were not affected by Cd exposure during this period. Branchial chloride cell numbers, identified as Na+/K+ -ATPase immunoreactive cells using immunohistochemistry, decreased 24 h after exposure but recovered thereafter. Histopathological changes did not follow a consistent pattern of variation with exposure time, and the alterations noted in gill epithelium were basically nonspecific to cadmium. Because of its tolerance, it can be concluded that the tilapia O. niloticus would not be a suitable test organism to evaluate sublethal toxicity of cadmium and the realistic impact of this pollutant in the environment. However, it certainly could contribute significantly to our understanding of the toxic mechanism of cadmium exposure in aquatic organisms. This is the first work to investigate the effect of waterborne pollutants on Na+/K+ -ATPase ,-subunit protein expression in fish gills. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 33,46, 2006. [source]

    Investigation of histopathological and cytogenetic effects on Lepomis gibbosus (Pisces: Perciformes) in the Çine stream (Ayd,n/Turkey) with determination of water pollution

    Yücel Ba, lu Koca
    Abstract Water quality and the distribution of some heavy metals in three different organs of Lepomis gibbosus from the Çine Stream were studied. Also, histopathological changes in gill, liver, and muscle tissue were examined at light microscopical level. Micronucleus (MN) formation in fish erytrocytes, as an indicator of chromosomal damage, has been increasingly used to detect the genotoxic potential of environmental contaminants. The frequency of MN was examined from samples of fish from the Çine Stream and a control group. MN frequency was higher in fish samples caught from the Çine Stream than that in the control group. The chemicals ammonia, nitrite, nitrate, orthophosphate, and sulphate were determined as parameters that possibly affect the gill, liver, and muscle morphology. Zn was the most accumulated metal in tissues as well as in water. Maximum metal accumulation occured in both liver and gills. For histopathological examinations, samples of gills, liver, and muscle tissues of L. gibbosus were studied by using light microscopy. In this study, a significant decrease in mean length of primary and secondary lamellae were observed. Moreover, cellular proliferation developed with secondary lamellae fusion, ballooning degenerations or club deformation of secondary lamellae, as well as distribution of necrotic, hyperplastic and clavate secondary lamellae. In the liver, altered staining, swollen and ruptured parenchymal cells, loss of cord structure, reduce of glycogen in hepatocytes, and vacuolar structure filled with cellular debris and many dark particles were seen. In muscle tissue, focal necrosis, cellular dissolution, and a decline or loss of striatation in muscle fibres were found. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 560,571, 2005. [source]

    Seasonal dynamics of the hepatotoxic microcystins in various organs of four freshwater bivalves from the large eutrophic lake Taihu of subtropical China and the risk to human consumption

    Jun Chen
    Abstract So far, little is known on the distribution of hepatotoxic microcystin (MC) in various organs of bivalves, and there is no study on MC accumulation in bivalves from Chinese waters. Distribution pattern and seasonal dynamics of MC-LR, -YR and -RR in various organs (hepatopancreas, intestine, visceral mass, gill, foot, and rest) of four edible freshwater mussels (Anodonta woodiana, Hyriopsis cumingii, Cristaria plicata, and Lamprotula leai) were studied monthly during Oct. 2003,Sep. 2004 in Lake Taihu with toxic cyanobacterial blooms in the summer. Qualitative and quantitative determinations of MCs in the organs were done by LC,MS and HPLC. The major toxins were present in the hepatopancreas (45.5,55.4%), followed by visceral mass with substantial amount of gonad (27.6,35.5%), whereas gill and foot were the least (1.8,5.1%). The maximum MC contents in the hepatopancreas, intestine, visceral mass, gill, foot, and rest were 38.48, 20.65, 1.70, 0.64, 0.58, and 0.61 ,g/g DW, respectively. There were rather good positive correlation in MC contents between intestines and hepatopancreas of the four bivalves (r = 0.75,0.97, p < 0.05). There appeared to be positive correlations between the maximum MC content in the hepatopancreas and the ,13C (r = 0.919) or ,15N (r = 0.878) of the foot, indicating that the different MC content in the hepatopancreas might be due to different food ingestion. A glutathione (GSH) conjugate of MC-LR was also detected in the foot sample of C. plicata. Among the foot samples analyzed, 54% were above the provisional WHO tolerable daily intake (TDI) level, and the mean daily intakes from the four bivalves were 8,23.5 times the TDI value when the bivalves are eaten as a whole, suggesting the high risk of consuming bivalves in Lake Taihu. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 572,584, 2005. [source]

    Histopathological alterations in the edible snail, Babylonia areolata (spotted babylon), in acute and subchronic cadmium poisoning

    P. Tanhan
    Abstract Histopathological alterations in 6- to 8-month-old juvenile spotted babylon, Babylonia areolata, from acute and subchronic cadmium exposure were studied by light microscopy. The 96-h LC50 value of cadmium for B. areolata was found to be 3.35 mg/L, and the maximum acceptable toxicant concentration (MATC) was 1.6 mg/L. Snails were exposed to 3.35 and 0.08 mg/L (5% of MATC) of cadmium for 96 h and 90 days, respectively. After exposure the gill, the organs of the digestive system (proboscis, esophagus, stomach, digestive gland, and rectum), and the foot were analyzed for cadmium accumulation. The results showed that most digestive organs had a high affinity for cadmium. The main target organ was the stomach, which could accumulate on average 1192.18 ,g/g dry weight of cadmium. Cadmium was shown to accumulate to a lesser extent in the digestive gland, gill, rectum, esophagus, proboscis, and foot. Histopathological alterations were observed in the gill and digestive organs (proboscis, esophagus, stomach, and rectum). The study showed that the stomach and gill were the primary target organs of both acute and subchronic exposure. Gill alterations included increased size of mucous vacuoles, reduced length of cilia, dilation and pyknosis of nuclei, thickening of basal lamina, and accumulation of hemocytes. The epithelial lining of the digestive tract showed similar alterations such as increased size of mucous vacuoles, reduced length of cilia, and dilation of nuclei. In addition, fragmentation of the muscle sheath was observed. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 142,149, 2005. [source]

    Hydrocarbon-induced changes to metabolic and detoxification enzymes of the Australian crimson-spotted rainbowfish (Melanotaenia fluviatilis)

    Carmel A. Pollino
    Abstract The toxicity of petroleum hydrocarbons to marine aquatic organisms has been widely investigated; however, the effects on freshwater environments have largely been ignored. Selected biomarkers were measured in a freshwater species, the crimson-spotted rainbowfish (Melanotaenia fluviatilis). Fish were exposed to either a water-accommodated fraction (WAF) of crude oil or a dispersed crude oil water-accommodated fraction (DCWAF) for 3 days and were depurated for 14 days. Generally, biomarkers were altered following the short-term exposures but recovered after 14 days of depuration. Metabolic enzymes measured in gill tissue were citrate synthase and lactate dehydrogenase (LDH). As a result of WAF and DCWAF exposures, citrate synthase and LDH activities increased. Enzyme activities returned to control levels following depuration. Subsequent to the WAF exposure, hepatic ethoxyresorufin- O -deethylase (EROD) activity levels were higher than controls and they returned to control levels during depuration. For the DCWAF exposure, EROD was induced by a TPH (total petroleum hydrocarbons) concentration of 14.5 mg/L; however, after depuration the 14.5 mg/L TPH group had lower EROD activity than did controls. There were no changes in liver- to body-weight ratios or the histopathological organization of gill or liver tissues. As the majority of biomarkers returned to control levels after 14 days of depuration, rainbowfish were able to recover from short-term exposures to crude oil and dispersed crude oil. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 21,28, 2003. [source]

    Effects of salinity on copper accumulation in the common killifish (Fundulus heteroclitus)

    Jonathan Blanchard
    Abstract Results of laboratory and field studies have demonstrated that salinity influences the accumulation of copper. The present study is, to our knowledge, the first to examine the effect of salinity on copper accumulation in a teleost fish across a comprehensive range of salinity from freshwater to seawater. This was done in an effort to identify potential target tissues and differences in chemical interactions across salinities that will aid in the development of a seawater biotic ligand model (BLM) for copper. Killifish (Fundulus heteroclitus) were acclimated to five salinities (0, 5, 11, 22, and 28 ppt) and exposed to three copper concentrations (0 [nominal], 30, and 150 ,g L,1), yielding 15 treatment groups. Fish from each group were sampled for tissue copper analysis at 0, 4, 12, and 30 d postexposure. Whole-body and liver accumulations were highest at lower salinities. The liver accounted for 57 to 86% of the whole-body copper even though it accounted for less than 4% of the body mass. Similarly, the gill accumulated more copper at lower salinities, whereas the intestine generally accumulated more copper at higher salinities. Speciation calculations indicate that CuCO3 likely accounts for much of the accumulation, possibly with some contributions from CuOH+ and Cu(OH)2. The free ion, Cu2+, does not appear to be associated with copper accumulation. However, the differences in physiology and in the concentrations of competing cations across salinities suggest that speciation alone cannot explain accumulation. The present findings may have implications for future development of a BLM for saline environments by identifying potential target tissues. [source]

    Molecular cloning of cytochrome P4501A cDNA of medaka (Oryzias latipes) and messenger ribonucleic acid regulation by environmental pollutants

    Jisung Ryu
    Abstract The sequence of cytochrome P4501A (CYP1A) cDNA of medaka (Oryzias latipes) was determined, and its messenger ribonucleic acid (mRNA) regulation by ,-naphthoflavone (,NF) was evaluated. The determined cDNA sequence contained 2,349 base pairs (bp), and the open reading frame contained a total of 1,563 bp encoding 521 predicted amino acids. The induction of CYP1A mRNA in medaka was evaluated using reverse transcription,polymerase chain reaction. The concentration,dependent induction of CYP1A mRNA in the liver was observed after exposure to ,NF at nominal concentrations of 20, 100, and 500 ,g/ L for 2 d. Time-dependent changes of CYP1A mRNA levels were also observed in the liver, gill, gut, and caudal fin tissues of medaka exposed to 100 ,g/L of ,NF for 7 d. Our results showed that the degree of CYP1A mRNA induction in the gill, gut, and caudal fin after exposure to ,NF was relatively higher than that in the liver, possibly because of low basal levels of CYP1A mRNA in the gill, gut, and caudal fin of nonexposed fish. The induction of medaka CYP1A mRNA was also observed after exposure to an environmental sample, landfill leachate. The CYP1A mRNA inductions in the gill, gut, and caudal fin were also higher than that in the liver as shown in the ,NF-treated groups. These results show that CYP1A mRNA determination in the gill, gut, and caudal fin, which are in direct contact with the polluted water, may become a useful method for monitoring CYP1A-inducible chemicals. [source]

    cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata

    FEBS JOURNAL, Issue 19 2005
    Shuo Li
    Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca2+ -binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca2+ -dependent electrophoretic shift, Ca2+ -binding activity and significant Ca2+ -induced conformational changes. Ca2+ -dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism. [source]

    Hygrocybe rigelliae (Velen.) E.Ludwig comb. nov. und Hygrocybe roseascens sp. nova, eine nahestehende Art aus der Untergattung Cuphophyllus (Agaricales, Hygrophoraceae, Tricholomataceae),

    FEDDES REPERTORIUM, Issue 1-2 2004
    E. Ludwig
    Die Literatur zu Hygrophorus rigelliaeVelen. wird diskutiert, die Art wird zu Hygrocybe umkombiniert. Eine eng verwandte, neue Spezies , Hygrocybe roseascens , mit (nach Entwässerung) auffallenden rosa Tönen auf dem teilweise schuppigen Hut, 1,4-sporigen Basidien und kleinen, (sub)globosen Sporen wird beschrieben. Die Unterschiede zu anderen Arten werden diskutiert. Eine Tafel mit Habituszeichnungen und den mikroskopischen Merkmalen wird beigegeben. Eine Farbtafel der neuen Art wird im Band III meines Pilzkompendiums veröffentlicht werden, steht aber bereits jetzt im Internet unter ("Pilzbilder") zur Verfügung. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Hygrocybe rigelliae (Velen.) E.Ludwig comb. nov. and Hygrocybe roseascens sp. nova, a tiny related species from the subspecies Cuphophyllus (Agaricales, Hygrophoraceae, Tricholomataceae) The literature on Hygrophorus rigelliaeVelen. is studied and the species is transferred to Hygrocybe. A related tiny wax gill, Hygrocybe roseascens, likewise belonging to subgenus Cuphophyllus is described as a new one. It is characterised by partly squamulose pileus with conspicuously pinkish hues when dry, 1,4-spored basidia and small, (sub)globose spores. The differences between the new species and similar taxa are discussed. A plate with drawings of its habit and microscopic features is given. A coloured plate will be published in Vol. III of my "Pilzkompendium" but is already available at ("Pilzbilder"). [source]

    Flavobacterium columnare chemotaxis to channel catfish mucus

    Phillip H. Klesius
    Abstract Flavobacterium columnare is a Gram-negative pathogen of many species of wild and cultured fish. Isolates from diseased channel catfish belong to either genomovar I or II. Genomovar II isolates were found to be more virulent than genomovar I isolates. The objective of the present study was to determine whether differences exist in the chemotactic response of these genomovars to mucus obtained from the skin, gills and intestines of healthy channel catfish using the capillary chemotaxis assay. Mucus from the skin and gill induced a greater chemotactic response by F. columnare than mucus from the intestine. Sixty percent of mucus from the skin of individual catfish yielded a positive chemotactic response from F. columnare. Finally, skin mucus induced a greater chemotactic response in genomovar II F. columnare than in genomovar I F. columnare isolates. The data indicate that mucus from channel catfish results in a chemotactic response by F. columnare. This positive chemotactic response may be an important first step for F. columnare colonization of channel catfish skin or gills. Although the role that chemotaxis plays in the virulence of F. columnare is not fully defined, the chemotactic response of genomovar ll isolates suggests that chemotaxis is associated with virulence. [source]