Field study of cyclic hypoxic effects on gene expression in grass shrimp hepatopancreas.

Grass shrimp, Palaemonetes pugio, are widely used for ecological and toxicological research. They commonly experience cyclic hypoxia in their natural habitats. The response of grass shrimp to laboratory-controlled cyclic hypoxia has been studied in detail, but little is known about how field acclimatized grass shrimp regulate the gene expression and response to cyclic hypoxia.

Effects of pyrene exposure on sheepshead minnow (Cyprinodon variegatus) reproduction.

Polycyclic aromatic hydrocarbons are known to adversely affect survival, growth, and reproduction in many aquatic species. Adult female sheepshead minnow, Cyprinodon varietagus (SHM), were exposed to chronic, low levels of pyrene (12.5, 25, or 50 μg/L nominal concentrations) and the impact on reproductive ability and larval survival was assessed.

Gene expression profile of hepatopancreas from grass shrimp Palaemonetes pugio exposed to cyclic hypoxia.

Estuarine organisms often experience periods of cyclic hypoxia characterized by hypoxia in the early morning and normoxia in the afternoon. Here we examine the genomic responses of grass shrimp, Palaemonetes pugio, exposed to cyclic hypoxia in the laboratory. Differentially expressed genes in the hepatopancreas were determined in cyclic hypoxic vs.

Effects of chronic nanoparticulate silver exposure to adult and juvenile sheepshead minnows (Cyprinodon variegatus).

The use of nanoparticulate silver (AgNP) is increasingly widespread and recently has been shown to have a plausible release route into aquatic environments. To date, relatively little research has examined the effects of AgNP on estuarine fish. The authors present data indicating that chronic exposure to low levels of AgNP induces significant adverse effects in both juvenile and adult sheepshead minnows (Cyprinodon variegarus; SHMs).

Constructing a fish metabolic network model.

We report the construction of a genome-wide fish metabolic network model, MetaFishNet, and its application to analyzing high throughput gene expression data. This model is a stepping stone to broader applications of fish systems biology, for example by guiding study design through comparison with human metabolism and the integration of multiple data types. MetaFishNet resources, including a pathway enrichment analysis tool, are accessible at http://metafishnet.

Linking probe thermodynamics to microarray quantification.

Understanding the difference in probe properties holds the key to absolute quantification of DNA microarrays. So far, Langmuir-like models have failed to link sequence-specific properties to hybridization signals in the presence of a complex hybridization background. Data from washing experiments indicate that the post-hybridization washing has no major effect on the specifically bound targets, which give the final signals.

Generation, analysis and functional annotation of expressed sequence tags from the sheepshead minnow (Cyprinodon variegatus).

Background: Sheepshead minnow (Cyprinodon variegatus) are small fish capable of withstanding exposure to very low levels of dissolved oxygen, as well as extreme temperatures and salinities. It is an important model in understanding the impacts and biological response to hypoxia and co-occurring compounding stressors such as polycyclic aromatic hydrocarbons, endocrine disrupting chemicals, metals and herbicides. Here, we initiated a project to sequence and analyze over 10,000 ESTs generated from the Sheepshead minnow (Cyprinodon variegatus) as a resource for investigating stressor responses.

Bioinformatic analysis of expressed sequence tags from grass shrimp Palaemonetes pugio exposed to environmental stressors.

Six libraries of expressed sequence tags (ESTs) were constructed by suppression subtractive hybridization (SSH) from the grass shrimp, Palaemonetes pugio, exposed to environmental stress: severe (Dissolved Oxygen (DO) 1.5 mg/L) and moderate (DO 2.5 mg/L) chronic hypoxia, cyclic hypoxia (1.

Gene expression profile of grass shrimp Palaemonetes pugio exposed to chronic hypoxia.

DNA microarrays have become an important tool to measure global gene expression changes and genetic pathways involved in response to environmental stressors and toxicants. In this study a cDNA microarray was designed and constructed from six libraries of expressed sequence tags generated in a previous study (Li, T., Brouwer, M.

Beyond Affymetrix arrays: expanding the set of known hybridization isotherms and observing pre-wash signal intensities.

Microarray hybridization studies have attributed the nonlinearity of hybridization isotherms to probe saturation and post-hybridization washing. Both processes are thought to distort 'true' target abundance because immobilized probes are saturated with excess target and stringent washing removes loosely bound targets. Yet the paucity of studies aimed at understanding hybridization and dissociation makes it difficult to align physicochemical theory to microarray results.

A competitive hybridization model predicts probe signal intensity on high density DNA microarrays.

A central, unresolved problem of DNA microarray technology is the interpretation of different signal intensities from multiple probes targeting the same transcript. We propose a competitive hybridization model for DNA microarray hybridization. Our model uses a probe-specific dissociation constant that is computed with current nearest neighbor model and existing parameters, and only four global parameters that are fitted to Affymetrix Latin Square data.

Changes in mitochondrial gene and protein expression in grass shrimp, Palaemonetes pugio, exposed to chronic hypoxia.

Spatial and temporal increases of hypoxia in estuaries are of major environmental concern. Since mitochondria consume most of the oxygen in the cell, we examined the potential role of mitochondrial gene and protein expression in adaptation to chronic hypoxia in the grass shrimp Palaemonetes pugio. Grass shrimp were exposed to DO levels slightly above and below the critical pO(2), 1.

Effects of cyclic hypoxia on gene expression and reproduction in a grass shrimp, Palaemonetes pugio.

Cyclic changes in dissolved oxygen occur naturally in shallow estuarine systems, yet little is known about the adaptations and responses of estuarine organisms to cyclic hypoxia. Here we examine the responses of Palaemonetes pugio, a species of grass shrimp, to cyclic hypoxia (1.5-8 mg/l dissolved oxygen; 4.

Molecular and developmental effects of exposure to pyrene in the early life-stages of Cyprinodon variegatus.

Polycyclic aromatic hydrocarbons (PAHs) have been connected to developmental toxicity in the early life-stages of many species by their ability to bind to the aryl hydrocarbon receptor (AHR), which dimerizes with ARNT (AHR nuclear translocator) to induce transcription of genes such as CYP1A1. ARNT also dimerizes with HIF (hypoxia-inducible factor alpha) to induce transcription of genes such as VEGF (vascular endothelial growth factor), suggesting that PAHs may interfere with transcription of VEGF by competing for ARNT. Herein, we address the molecular and developmental effects of exposures to the weak AHR agonist pyrene on the early life-stages of the sheepshead minnow Cyprinodon variegatus.

Hypoxia-inducible factor, gsHIF, of the grass shrimp Palaemonetes pugio: molecular characterization and response to hypoxia.

Hypoxia-inducible factor 1alpha (HIF-1alpha) is a key transcription factor that controls a variety of cellular and systemic homeostatic responses to hypoxic stress. Expression and function of HIF-1alpha have not been studied in crustaceans, which experience wide fluctuations of oxygen tensions in their aquatic environment. Here we show that an HIF-1alpha homolog, gsHIF, is present in the hypoxia-tolerant grass shrimp Palaemonetes pugio.

Antiestrogens inhibit xenoestrogen-induced brain aromatase activity but do not prevent xenoestrogen-induced feminization in Japanese medaka (Oryzias latipes).

In fish, exposure to estrogen or estrogen-mimicking chemicals (xenoestrogens) during a critical period of development can irreversibly invert sex differentiation. In medaka, a male-to-female reversal upon exposure to a xenoestrogen is accompanied by an increase in brain aromatase expression and activity. However, whether this increase is the direct cause of sex reversal is unknown.

Brain aromatase in Japanese medaka (Oryzias latipes): Molecular characterization and role in xenoestrogen-induced sex reversal.

In female fish estrogen is required for the development of primary and secondary sex characteristics and is derived from the aromatization of androgens by aromatase. There are two isoforms of aromatase in several teleost species, brain and ovarian. The objective of this study was two-fold: clone and sequence the coding and promoter region of brain aromatase in medaka, and determine the effects of exposure to an environmental estrogen (o,p-DDT) on sex determination and brain aromatase transcription and activity.

Rationale for a new generation of indicators for coastal waters.

More than half the world's human population lives within 100 km of the coast, and that number is expected to increase by 25% over the next two decades. Consequently, coastal ecosystems are at serious risk. Larger coastal populations and increasing development have led to increased loading of toxic substances, nutrients and pathogens with subsequent algal blooms, hypoxia, beach closures, and damage to coastal fisheries.

Effects of hypoxia on gene and protein expression in the blue crab, Callinectes sapidus.

Increases in hypoxic conditions are one of the major factors responsible for declines in estuarine habitat quality, yet to date there are no indicators for recognizing populations of estuarine organisms that are suffering from chronic hypoxic stress. Here we test the hypothesis that alterations in gene and protein expression of antioxidant enzymes and other stress-specific proteins can be used as molecular indicators of hypoxic stress. Blue crabs, Callinectes sapidus, were exposed to 2-3 ppm DO for 5 days.

Cloning, sequencing and phylogenetic/phenetic classification of an estrogen receptor alpha (alpha) subtype of sheepshead minnow (Cyprinodon variegatus).

The estrogen receptor (ER) is a key component of the reproductive system of both teleosts and tetrapods. In this study, the sequence and evolutionary relationship of sheepshead minnow (Cyprinodon variegatus) ER were examined. Total RNA from livers of adult laboratory-reared gravid female C.

Replacement of a cytosolic copper/zinc superoxide dismutase by a novel cytosolic manganese superoxide dismutase in crustaceans that use copper (haemocyanin) for oxygen transport.

The blue crab, Callinectes sapidus, which uses the copper-dependent protein haemocyanin for oxygen transport, lacks the ubiquitous cytosolic copper-dependent enzyme copper/zinc superoxide dismutase (Cu,ZnSOD) as evidenced by undetectable levels of Cu,ZnSOD activity, protein and mRNA in the hepatopancreas (the site of haemocyanin synthesis) and gills. Instead, the crab has an unusual cytosolic manganese SOD (cytMnSOD), which is retained in the cytosol, because it lacks a mitochondrial transit peptide. A second familiar MnSOD is present in the mitochondria (mtMnSOD).

Reproductive effects of estrogenic and antiestrogenic chemicals on sheepshead minnows (Cyprinodon variegatus).

Environmental estrogens can activate genes of the reproductive system, such as vitellogenin (VTG), a precursor to egg yolk protein, by activating the estrogen receptor (ER), whereas antiestrogens can inhibit ER activation. Adult lab-reared male sheepshead minnows (Cyprinodon variegatus) were exposed to estrogenic 4-tert-octylphenol (OP) and females to antiestrogenic cadmium (Cd), and the effects on four potential indicators of impaired reproductive function were examined: VTG in F0 male blood as sign of feminization, F0 generation fecundity/fertility, embryonic development/egg hatching/survival rate of F1 generation fry, and F0 gonadal histology. Mean VTG in the control, 11.

p-Nitrophenol and glutathione response in medaka (Oryzias latipes) exposed to MX, a drinking water carcinogen.

When chlorine is introduced into public drinking water for disinfection, it can react with organic compounds in surface waters to form toxic by-products such as 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX). We investigated the effect of exposure to MX on cytochrome P450 2E1 (CYP2E1)-like activity and total glutathione (GSH) in the liver of the small fish model, medaka (Oryzias latipes). The multi-site carcinogen methylazoxymethanol acetate (MAMAc) was the positive control compound.

Role of a copper-specific metallothionein of the blue crab, Callinectes sapidus, in copper metabolism associated with degradation and synthesis of hemocyanin.

We have identified three MT encoding genes in the blue crab: MT-I, inducible by cadmium, zinc and copper; MT-II, inducible by cadmium and zinc; and MT-III, inducible by copper only [Syring et al., Comp. Biochem.

METAL REGULATION AND MOLTING IN THE BLUE CRAB, CALLINECTES SAPIDUS: METALLOTHIONEIN FUNCTION IN METAL METABOLISM.

We recently demonstrated that zinc, copper, and hemocyanin metabolism in the blue crab varies as a function of the molt cycle. To extend these observations, and better delineate metal metabolism in marine crustaceans, we have conducted experiments to determine if environmental temperature and season of the year affect concentrations of hemocyanin and copper in the hemolymph and copper and zinc in the digestive gland. Overwintering, cold water crabs (6°C) had decreased hemocyanin and copper in the hemolymph and normal zinc and copper in the digestive gland with respect to summer crabs collected at 20-30°C.