Proteomics: Applications and Advances 18.5 Environment 485
Part C | 18.5
for Mercury Research stated that commercially important seafood such as lobster, tuna, and swordfish have
muscle mercury concentrations (0:220:95 ppm, wet
weight (ww)) that exceed the consumption guideline of
one meal per month [18.69]. Since information regarding the molecular mechanisms of mercury neurotoxicity in fish is scarce, Berg et al. [18.68] conducted a proteomic study of Atlantic cod (Gadus morhua) brain
tissue from fish exposed to methylmercury (MeHg)
for 2 weeks after being injected intraperitoneally with
MeHg at a concentration of 0:5 or 2 mg=kg. Although
many of the proteins that were significantly expressed
in response to MeHg had already been shown to respond to MeHg in mammals, confirming the validity of
the data, the study also identified a number of proteins
that have critically important, nervous system-specific
functions that had never been associated with MeHg.
These proteins included pyridoxal kinase (essential for
the synthesis of several neurotransmitters), G protein
(coupled to neurotransmitter receptors), nicotinamide
phosphoribosyl-transferase (protects against axonal degeneration), dihydropyrimidinase-like 5 (axon guidance and regeneration), septin (dendrite development),
phosphatidylethanolamine binding protein (precursor
for hippocampal cholinergic neurostimulating peptide)
and protein phosphatase 1 (control of brain recovery by
synaptic plasticity) [18.68]. Not only has the data obtained from this study proved invaluable in confirming
the involvement of a number of molecular processes associated with MeHg exposure and toxicity, but it also
identified proteins that had not been investigated in the
context of MeHg accumulation, which may prove invaluable as biomarkers of MeHg contaminated fish.
Endocrine disrupting compounds (EDC) are a diverse group of anthropogenic chemicals that are occurring in ever increasing concentrations in the marine environment. EDCs, thought to be responsible for
the significant decline in many populations of aquatic
species in a number of geographical locations worldwide [18.70], can be defined as [18.71]:
an exogenous substance or mixture that alters the
function(s) of the endocrine system and consequently causes adverse health effects in an intact
organism or its progeny or (sub)populations.
EDCs interfere with hormonal function by binding to cytoplasmic oestrogen receptors and consequently, have been shown to affect sexual development,
growth, osmoregulation, stress, and immune responses
in fish [18.70, 72, 73]. Although the concentrations of
nonylphenol mixtures (NPs) and bisphenol A (BPA)
detected in polluted environments are much lower
(<10 g=L) than the median effective concentrations
(EC 50 ) of these compounds for marine invertebrates
such as adult Mytilus edulis and the adult cnidarian Hydra vulgaris (30 mg NPs/L [18.74] and 6:9 mg
BPA/L [18.75], respectively), environmental concentrations of EDCs have been reported to affect the more
susceptible larval stages of marine organisms [18.76].
Indeed, many invertebrate larvae settle on benthic diatoms that have been shown to biomagnify EDCs to
levels greater than those in the environment, making
them more likely to be harmful to the larval stage of
marine organisms [18.77].
Since not much information is available regarding the effect of EDCs on marine invertebrate larvae,
and since many of the life cycles of these animals
include larval settlement and ingestion of benthic diatoms, Liu et al. [18.76] used a proteomic approach
to investigate the effect of NPs and BPA on larval Haliotis diversicolor supertexta (a commercially
important abalone from Taiwan). The study showed
that toxicity of the EDCs towards the abalone larvae
increased due to EDC accumulation by the diatom
Navicula incerta that was used as a settlement substrate in the experimental setup. Larval proteins affected
by EDC exposure function in ATP synthesis (downregulated), the stress and defence response (up-regulated), metabolism, signal transduction (up-regulated),
cytoskeleton (mostly down-regulated), and cilia formation (down-regulated) [18.76]. Consequently, Liu
et al. [18.76] suggested that inhibition of ATP synthesis, actin, ˇ-tubulin, and cilia formation protein could
explain the malformations observed during embryogenesis and consequent failure of metamorphosis in
Haliotis diversicolor supertexta larvae settled on Navicula incerta exposed to EDCs.
18.5.3 Population Proteomics
Marine fish populations are under severe pressure due
to over-exploitation in conjunction with the effects of
climate change and pollution, and consequently, it is
becoming increasingly important that fish populations
be accurately defined and characterized if wild fisheries
and fish biodiversity are to be sustained and protected.
Indeed, a United Nations report states that more than
two-thirds of the world’s fisheries have been overfished
or fully harvested, and more than one third is in a state
of decline due to lost habitats, increasing pollution levels, and climate change [18.78]. Although traditional
population studies of marine fish have been conducted
Part C | 18.5
for Mercury Research stated that commercially important seafood such as lobster, tuna, and swordfish have
muscle mercury concentrations (0:220:95 ppm, wet
weight (ww)) that exceed the consumption guideline of
one meal per month [18.69]. Since information regarding the molecular mechanisms of mercury neurotoxicity in fish is scarce, Berg et al. [18.68] conducted a proteomic study of Atlantic cod (Gadus morhua) brain
tissue from fish exposed to methylmercury (MeHg)
for 2 weeks after being injected intraperitoneally with
MeHg at a concentration of 0:5 or 2 mg=kg. Although
many of the proteins that were significantly expressed
in response to MeHg had already been shown to respond to MeHg in mammals, confirming the validity of
the data, the study also identified a number of proteins
that have critically important, nervous system-specific
functions that had never been associated with MeHg.
These proteins included pyridoxal kinase (essential for
the synthesis of several neurotransmitters), G protein
(coupled to neurotransmitter receptors), nicotinamide
phosphoribosyl-transferase (protects against axonal degeneration), dihydropyrimidinase-like 5 (axon guidance and regeneration), septin (dendrite development),
phosphatidylethanolamine binding protein (precursor
for hippocampal cholinergic neurostimulating peptide)
and protein phosphatase 1 (control of brain recovery by
synaptic plasticity) [18.68]. Not only has the data obtained from this study proved invaluable in confirming
the involvement of a number of molecular processes associated with MeHg exposure and toxicity, but it also
identified proteins that had not been investigated in the
context of MeHg accumulation, which may prove invaluable as biomarkers of MeHg contaminated fish.
Endocrine disrupting compounds (EDC) are a diverse group of anthropogenic chemicals that are occurring in ever increasing concentrations in the marine environment. EDCs, thought to be responsible for
the significant decline in many populations of aquatic
species in a number of geographical locations worldwide [18.70], can be defined as [18.71]:
an exogenous substance or mixture that alters the
function(s) of the endocrine system and consequently causes adverse health effects in an intact
organism or its progeny or (sub)populations.
EDCs interfere with hormonal function by binding to cytoplasmic oestrogen receptors and consequently, have been shown to affect sexual development,
growth, osmoregulation, stress, and immune responses
in fish [18.70, 72, 73]. Although the concentrations of
nonylphenol mixtures (NPs) and bisphenol A (BPA)
detected in polluted environments are much lower
(<10 g=L) than the median effective concentrations
(EC 50 ) of these compounds for marine invertebrates
such as adult Mytilus edulis and the adult cnidarian Hydra vulgaris (30 mg NPs/L [18.74] and 6:9 mg
BPA/L [18.75], respectively), environmental concentrations of EDCs have been reported to affect the more
susceptible larval stages of marine organisms [18.76].
Indeed, many invertebrate larvae settle on benthic diatoms that have been shown to biomagnify EDCs to
levels greater than those in the environment, making
them more likely to be harmful to the larval stage of
marine organisms [18.77].
Since not much information is available regarding the effect of EDCs on marine invertebrate larvae,
and since many of the life cycles of these animals
include larval settlement and ingestion of benthic diatoms, Liu et al. [18.76] used a proteomic approach
to investigate the effect of NPs and BPA on larval Haliotis diversicolor supertexta (a commercially
important abalone from Taiwan). The study showed
that toxicity of the EDCs towards the abalone larvae
increased due to EDC accumulation by the diatom
Navicula incerta that was used as a settlement substrate in the experimental setup. Larval proteins affected
by EDC exposure function in ATP synthesis (downregulated), the stress and defence response (up-regulated), metabolism, signal transduction (up-regulated),
cytoskeleton (mostly down-regulated), and cilia formation (down-regulated) [18.76]. Consequently, Liu
et al. [18.76] suggested that inhibition of ATP synthesis, actin, ˇ-tubulin, and cilia formation protein could
explain the malformations observed during embryogenesis and consequent failure of metamorphosis in
Haliotis diversicolor supertexta larvae settled on Navicula incerta exposed to EDCs.
18.5.3 Population Proteomics
Marine fish populations are under severe pressure due
to over-exploitation in conjunction with the effects of
climate change and pollution, and consequently, it is
becoming increasingly important that fish populations
be accurately defined and characterized if wild fisheries
and fish biodiversity are to be sustained and protected.
Indeed, a United Nations report states that more than
two-thirds of the world’s fisheries have been overfished
or fully harvested, and more than one third is in a state
of decline due to lost habitats, increasing pollution levels, and climate change [18.78]. Although traditional
population studies of marine fish have been conducted