Alkaline phosphatases are non-specific phosphomonoesterases that are distributed widely in species ranging from bacteria to man. This study has concentrated on the tissue-nonspecific alkaline phosphatase from arctic shrimps (shrimp alkaline phosphatase, SAP). Originating from a cold-active species, SAP is thermolabile and is used widely in vitro, e.g. to dephosphorylate DNA or dNTPs, since it can be inactivated by a short rise in temperature. Since alkaline phosphatases are zinc-containing enzymes, a multiwavelength anomalous dispersion (MAD) experiment was performed on the zinc K edge, which led to the determination of the structure to a resolution of 1.9 A. Anomalous data clearly showed the presence of a zinc triad in the active site, whereas alkaline phosphatases usually contain two zinc and one magnesium ion per monomer. SAP shares the core, an extended beta-sheet flanked by alpha-helices, and a metal triad with the currently known alkaline phosphatase structures (Escherichia coli structures and a human placental structure). Although SAP lacks some features specific for the mammalian enzyme, their backbones are very similar and may therefore be typical for other higher organisms. Furthermore, SAP possesses a striking feature that the other structures lack: surface potential representations show that the enzyme's net charge of -80 is distributed such that the surface is predominantly negatively charged, except for the positively charged active site. The negatively charged substrate must therefore be directed strongly towards the active site. It is generally accepted that optimization of the electrostatics is one of the characteristics related to cold-adaptation. SAP demonstrates this principle very clearly.
We investigated the deep-sea fossil record of benthic ostracodes during periods of rapid climate and oceanographic change over the past 20,000 years in a core from intermediate depth in the northwestern Atlantic. Results show that deep-sea benthic community "collapses" occur with faunal turnover of up to 50% during major climatically driven oceanographic changes. Species diversity as measured by the Shannon-Wiener index falls from 3 to as low as 1.6 during these events. Major disruptions in the benthic communities commenced with Heinrich Event 1, the Inter-Allerød Cold Period (IACP: 13.1 ka), the Younger Dryas (YD: 12.9-11.5 ka), and several Holocene Bond events when changes in deep-water circulation occurred. The largest collapse is associated with the YD/IACP and is characterized by an abrupt two-step decrease in both the upper North Atlantic Deep Water assemblage and species diversity at 13.1 ka and at 12.2 ka. The ostracode fauna at this site did not fully recover until approximately 8 ka, with the establishment of Labrador Sea Water ventilation. Ecologically opportunistic slope species prospered during this community collapse. Other abrupt community collapses during the past 20 ka generally correspond to millennial climate events. These results indicate that deep-sea ecosystems are not immune to the effects of rapid climate changes occurring over centuries or less.
The crustacean hyperglycaemic hormones (cHHs) are multifunctional neuropeptides that play a central role in the physiology of crustaceans. A partial cDNA coding for cHH of the Norway lobster, Nephrops norvegicus, was cloned; this cDNA was fused to glutathione- S-transferase (GST) to obtain a recombinant fusion protein that was used to raise a rabbit antiserum and to perform a biological assay. The specificity of the purified antibody was demonstrated by means of Western blotting. To validate the specificity of the purified antibody to the cHH of N. norvegicus and its cross-reactivity with other species, we performed standard immunocytochemistry of the eyestalk on: (1) paraffin sections of the decapod species N. norvegicus, Munida rugosa and Astacus leptodactylus and of the stomatopod Squilla mantis; (2) semithin resin sections of N. norvegicus and Palaemon elegans; (3) ultrathin sections of N. norvegicus sinus gland (transmission electron microscopy studies). The pattern of immunoreactivity shown by N. norvegicus eyestalk sections conforms to distribution, relative amount and ultrastructural features of cHH-containing neurons and nerve endings as reported in the previous literature. In all the crustacean species examined, the antibody marks precisely the X organ-sinus gland complex and unspecific staining is completely lacking. In addition, its specific cross-reaction by immunoprecipitation depletes shrimp eyestalk extract of hyperglycaemic activity in an in vivo bioassay. The results obtained show a cHH-specific molecular recognition despite the fact that the species tested belong to systematic groups increasingly remote in the phylogenetic tree. The antibody could be used for advancing our knowledge on cHH activity in a variety of crustacean species, e.g. for monitoring reproductive and stress conditions.
Material from Spitsbergen (Norway) collected by Spitzenberger (1996) was reinvestigated. A new genus Arctocypris and a new species Arctocypris. fuhrmanni n. gen. n. sp. are described in the present paper. A key to the genera of the subfamily Eucypridinae is provided. At the moment Arctocypris n. gen. comprises four species: Arctocypris arctica (Olofsson, 1918) comb. nov.; A. dulcifons (Diebel & Pietrzeniuk, 1969) comb. nov.; A. foveata (Delorme, 1968) comb. nov. and Arctocypris fuhrmanni n. gen., n. sp.
Activated carbon (AC) has long been associated with the capacity to effectively remove organic substances from aquatic and sediment matrices; however, its use in remediation purposes has drawn some concern due to possible impacts on benthic communities. Within the inner Oslofjord, the use of AC has been well documented for reducing the risks associated with dioxins or dioxin-like compounds from contaminated areas. However, benthic surveys performed on areas treated with AC have revealed that the abundance of organisms inhabiting these areas can be reduced significantly in the subsequent years following treatment. The reason for the reduction in the benthic communities is currently unknown, and therefore, an integrated approach to assess the effects of 2 different forms of AC (biogenic and petrogenic) on benthic organisms has been performed. A battery of 3 different benthic organisms with different feeding and life-cycle processes has been used encompassing sediment surface feeders, sediment ingestors, and sediment reworkers. Results of the tests indicated that although AC is not acutely toxic at concentrations up to 1000 mg/L, there may be physical effects of the substance on benthic dwelling organisms at environmentally relevant concentrations of AC at remediated sites.
As aquaculture production and the consumption of aquaculture products increase, the possibility of contracting zoonotic infections from either handling or ingesting these products also increases. The principal pathogens acquired topically from fish or shellfish through spine/pincer puncture or open wounds are Aeromonas hydrophila, Edwardsiella tarda, Mycobacterium marinum, Streptococcus iniae, Vibrio vulnificus and V. damsela. These pathogens, which are all indigenous to the aquatic environment, have also been associated with disease outbreaks in food fish. Outbreaks are often related to management factors, such as the quality and quantity of nutrients in the water and high stocking density, which can increase bacterial loads on the external surface of the fish. As a result, diseased fish are more likely to transmit infection to humans. This review provides an account of human cases of zoonoses throughout the world from the principal zoonotic pathogens of fish and shellfish.
To trace the biomagnification of organochlorines in marine food chains near Svalbard, which may lead to the high organochlorine concentrations in top predators from the area, we compared concentrations and patterns of organochlorines in selected taxa. The pelagic crustaceans, Calanus spp. (copepods), Thysanoessa spp. (euphausiids), Parathemisto libellula (amphipod), and the fish species, Boreogadus saida (polar cod) and Gadus morhua (cod) were selected to represent the lower trophic levels in the food web. Four seabird species were chosen at the higher trophic levels, Uria lomvia (Brünnich's guillemot), Cepphus grylle (black guillemot), Rissa tridactyla (black-legged kittiwake) and Larus hyperboreus (glaucous gull). We found low concentrations of the organochlorines sigma hexachlorocyclohexanes (sigma HCHs), hexachlorobenzene (HCB), sigma Chlordanes, sigma DDTs and sigma polychlorinated biphenyls (sigma PCBs) in crustaceans (11-50 ng g-1 lipid wt.) and fish (15-222 ng g-1 lipid wt.). In seabirds, the organochlorine concentrations biomagnified one to three orders of magnitude dependent on species and compound class. Glaucous gulls had the highest concentrations of all organochlorines. The organochlorine levels in all taxa except glaucous gull were comparable to those recorded in similar species in the Canadian Arctic. The organochlorine pattern changed from crustaceans and fish to seabirds. Moving up the food chain, the relative contribution of sigma HCHs, HCB and sigma Chlordanes decreased, and the relative contribution of sigma DDTs, sigma PCBs, persistent compounds and metabolites increased. The results reflected trophic transfer of organochlorines along the food chain as well as different elimination potentials due to direct diffusion in crustaceans and fish, and higher contaminant metabolic activity in seabirds.
Levels of polybrominated dibenzo-p-dioxins (PBDDs) were measured in marine fish, mussels, and shellfish. PBDDs were nondetectable in samples from freshwater environments, and their levels were successively higher in samples from the marine environments of the Bothnian Bay and Bothnian Sea, the West Coast of Sweden, and the Baltic Proper. In Baltic Proper littoral fish the levels of PBDDs generally exceeded those of their chlorinated analogues (PCDDs). This is alarming as some Baltic fish species already are contaminated by chlorinated dioxins to such an extent that they cannot be sold on the European market. By comparing spatial trends in PBDD and PCDD distributions, and PBDD patterns in fish, mussels, and algae, we show that the PBDDs are probably produced naturally, and we propose a route for their biosynthesis. We further show that the levels of PBDDs are high (ng/g wet weight) in mussels, and that the levels increase over time. Finally, we discuss the possibility that the PBDDs have adverse biological effects, and that the levels are increasing as a result of global warming and eutrophication.
Comment In: Environ Sci Technol. 2007 May 1;41(9):3033-417539497
The aim of this study was to investigate the microbial quality of whole Norway lobster (Nephrops norvegicus) and Norway lobster tails to optimize handling conditions. This was done by assessing the total viable count (TVC) and characterizing the dominant microbiota. The cultivable microorganisms were quantified via classical microbiological plating methods. To characterize as many bacterial species present as possible, we performed advanced molecular identification techniques (PCR-DGGE). The initial TVC of fresh Norway lobster meat was high (3.0 log cfu/g) as compared to fish. No significant difference between whole Norway lobster and Norway lobster tails could be found during the storage period. From day 6 of storage, a significant difference between Plate Count Agar (PCA) and Marine Agar (MA) was observed. The microbiota of Norway lobster was dominated by members of the Gram-negative genera such as Psychrobacter spp., Pseudoalteromonas spp., Pseudomonas spp., Luteimonas spp., and Aliivibrio spp. From these bacteria, mainly Psychrobacter spp. and Pseudomonas spp. remained present until the end of the storage period. These are known spoilage organisms in fishery products. Other known spoilage organisms of crustaceans such as Photobacterium spp. could not be identified.
Causes of macroevolutionary trends in body size, such as Cope's Rule, the tendency of body size to increase over time, remain poorly understood. We used size measurements from Cenozoic populations of the ostracode genus Poseidonamicus, in conjunction with phylogeny and paleotemperature estimates, to show that climatic cooling leads to significant increases in body size, both overall and within individual lineages. The magnitude of size increase due to Cenozoic cooling is consistent with temperature-size relationships in geographically separated modern populations (Bergmann's Rule). Thus population-level phenotypic evolution in response to climate change can be an important determinant of macroevolutionary trends in body size.