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PubMed2004

MtDNA sequencing from zooplankton after long-term preservation in buffered formalin.

Molecular genetic analysis of zooplankton has been slowed by the usual practice of preservation and storage of samples in dilute formalin solutions, which are not always adequately buffered for pH. We report here the determination of DNA sequences for Meganyctiphanes norvegica (Crustacea, Euphausiacea) preserved and stored in buffered formalin for up to 25 years. Specifically designed molecular protocols for DNA extraction and PCR amplification yielded valid sequence data for short (approximately 100-200 bp) regions of the mitochondrial cytochrome b (mtCYB) gene for individual euphausiids. Critical aspects of our approach include: extended extraction and proteinase-K digestion to maximize DNA yield; use of protocols requiring short DNA fragments; design of species-specific PCR primers to minimize risks of contamination by exogenous DNA; and comparison with published DNA sequences for the same gene and species. We conclude that the yield of DNA and the success of subsequent molecular analyses depend primarily on the length of time the tissue has been exposed to formalin and the pH of the solution. Zooplankton samples intended for molecular analysis should preferably be preserved and maintained in ethanol or deep-frozen, but long-term storage in buffered formalin does not preclude some types of molecular genetic analysis.

Animals↗
PubMed1978

Light and electron microscopic observations of feeding behavior, nutrition, and reproduction in laboratory cultures of Thalassicolla nucleata.

T. nucleata is a skeletonless, single-celled radiolarian commonly found in ocean surface water. Specimens were cultured in the laboratory in a seawater--antibiotic medium. Feeding experiments show that T. nucleata is omnivorous with preference for crustacea, colorless flagellates, and occasional diatoms. Pigmented algae bearing organic thecae are occasionally consumed, but Dunaliella sp. is rejected. Rhizopodial activity during algal predation is compared to activity during crustacean predation, and evidence for differentiation of function among rhizopodia is presented. Electron microscopic observations and evidence from cytochalasin B treatment support the hypothesis that microfilaments mediate organized rhizopodial streaming. Reproduction is by isospores which resemble those in other spumellarian Radiolaria. Survival time in laboratory culture indicates that T. nucleata has a life span of at least 3 weeks. These findings are discussed in relation to the unique requirements imposed by a pelagic habitat on survival of a single-celled floating organism.

Animals↗
PubMed2006

Biology and ecology of the hydrocoral millepora on coral reefs.

Millepores are colonial polypoidal hydrozoans secreting an internal calcareous skeleton of an encrusting or upright form, often of considerable size. Defensive polyps protruding from the skeleton are numerous and highly toxic and for this reason millepores are popularly known as "stinging corals" or "fire corals." In shallow tropical seas millepore colonies are conspicuous on coral reefs and may be locally abundant and important reef-framework builders. The history of systematic research on the Milleporidae and the sister family Stylasteridae is rich and full with the works of early naturalists beginning with Linnaeus. Seventeen living millepore species are recognised. Marked phenotypic variation in form and structure of colonies is characteristic of the genus Millepora. The first published descriptions of the anatomy and histology of millepores were by H. N. Moseley in one of the Challenger Expedition reports. These original, detailed accounts by Moseley remain valid and, except for recent descriptions of the ultrastructure of the skeleton and skeletogenic tissues, have not needed much modification. Millepores occur worldwide on coral reefs at depths of between 1 and 40 m and their distribution on reefs is generally zoned in response to physical factors. Colonies may be abundant locally on coral reefs but usually comprise <10% of the overall surface cover. Growth rates of colonies are similar to the measured rates of branching and platelike scleractinian corals. Millepores are voracious zooplankton feeders and they obtain part of their nutrition from autotrophic sources, photosynthetic production by symbiotic zooxanthellae. Reproduction in millepores is characterised by alternation of generations with a well-developed polypoid stage that buds off planktonic medusae. Sexual reproduction is seasonal for known species and the medusae have a brief planktonic life. Asexual production is achieved by sympodial growth, the production of new skeleton and soft tissue along a growing edge or branch tip, and by the reattachment, regeneration and repair of damaged or broken colony fragments. The physiological and ecological responses of species of millepores are similar to those of the species of scleractinian corals over a broad range of natural and anthropogenic disturbances. Severe damage to colonies may occur during major storms. Delicately branching species are more susceptible than massive and bladed species. The ability of broken fragments to regenerate can ameliorate the extent of damage. Widespread bleaching and mortality of millepores has been reported during mass bleaching events that have affected many coral reefs. Millepores are often the first to recover after short-term bleaching events. Harmful effects of oil spills, chronic oil pollution and oil-spill detergents have been widely reported for millepores. Although the hydrozoan coenosarc, with its fiercely stinging zooids, does not appear to be an attractive substratum for attachment and settlement of epizooans, a number of sessile and errant forms commonly occur on millepores. These include barnacles, amphipods, tanaid and alpheid crustaceans, polychaetes and gastropods. Burrowing molluscs, polychaetes and crustacea also abound. Many of these species or their close relatives also occur on scleractinian corals. A variety of predators, grazers and fouling organisms occur on millepores. These include errant polychaetes, several coral-feeding fish and a gastropod mollusc. Various invasive green, red and brown algae are widespread, growing on dead branches of millepores and overgrowing live coral tissue. Various "band diseases" associated with microorganisms that appear to cause lesions on millepores and loss of tissue have been documented but are not of widespread occurrence. Infestations of endolithic algae and fungi growing within the skeletons have been reported in a number of millepore species.

Animals↗
PubMed2001

Species-specific elimination of polychlorinated biphenyls in estuarine animals and its impact on residue patterns.

Elimination kinetics of tetra-, penta- and hexachlorobiphenyls (IUPAC Nos. 44, 52, 87, 95, 101, 153) were investigated by laboratory experiments in three species of different phyla: Nereis diversicolor (Polychaeta), Palaemon longirostris (Crustacea) and Platichthys flesus (Pisces). Half-lives were species-specific and structure-dependent. Palaemon longirostris eliminated all components fastest. N. diversicolor was faster than Platichthys flesus except for components 95 and 153. Contrary to the fish species, the two invertebrates contained significant amounts of polar transformation products of No. 52, which had been applied as 14C labelled. Therefore, the faster elimination by Palaemon longirostris and N. diversicolor was assumed to be generally due to increased biotransformation. Elimination was in accordance with polychlorinated biphenyl (PCB) residue patterns obtained from field samples of the species. Congeners with vicinal H atoms in m,p positions were under-represented in Palaemon longirostris and so were congeners with > or = 7 Cl in N. diversicolor, while the PCB residue pattern in Platichthys flesus was similar to that of Clophen A60. By comparing percentages of the experimental congeners in sigma PCB and their elimination half-lives in the three species, it was revealed that residue patterns were also influenced by species-dependent uptake, e.g. feeding habits. Extractable organic matter-based sigma PCB levels increased with trophic levels of the three species.

Animals↗
PubMed2001

Impairment of mysid (Neomysis integer) swimming ability: an environmentally realistic assessment of the impact of cadmium exposure.

Neomysis integer (Crustacea: Mysidacea), a euryhaline member of the hyperbenthos of the upper reaches of European estuaries, has been identified as a suitable animal for assessing the impacts of chemical pollutants on these estuarine regions. In this study, the effect of a 7 day pre-exposure to environmentally relevant concentrations of cadmium (0.5 and 1.0 microg l(-1)) on the swimming behaviour of N. integer was examined using an annular flume. Cadmium speciation at two salinities (1 and 10 per thousand) that dominate these upper estuarine regions was modelled to ensure mysids were exposed to the same concentration of the toxic free-ion at each salinity. There was no significant difference in the swimming behaviour of mysids exposed to the same free-ion cadmium concentration at the two different salinities. At each salinity, exposure to 0.5 microg Cd2+ (aq) l(-1)resulted in fewer mysids moving forward into the current (normal behaviour) at free stream velocities typical of their natural habitat (e.g. 3-9 cm s(-1)) than non cadmium-exposed mysids. At these low current speeds, cadmium-exposed mysids were either able to maintain position or were swept by the current. The same general responses were recorded for mysids exposed to 1.0 microg Cd2+ (aq) l(-1)except that more mysids showed disrupted swimming ability compared with 0.5 microg Cd2+ (aq) l(-1). At higher current speeds (>12 cm s(-1)), current velocity was the dominant factor affecting mysid swimming behaviour and there was no effect of cadmium on mysids maintaining position. Exposure to cadmium also caused significant disruption of the hyperbenthic behaviour of N. integer and more cadmium-exposed individuals were in the water column than control mysids; this result was more variable at 10 per thousand than 1 per thousand. Results indicate that exposure to cadmium concentrations of 0.5 microg Cd2+(aq) l(-1)would result in displacement of N. integer from its optimum region within the estuarine environment. This conclusion would not be achieved from standard LC(50) tests (e.g. 7 day LC50 = 2.95 microg Cd2+ (aq) l(-1)), highlighting the value of behavioural disruption as a sensitive indicator of environmental chemical contamination.

Animals↗
PubMed1999

Tachykinin-related peptides in invertebrates: a review.

Peptides with sequence similarities to members of the tachykinin family have been identified in a number of invertebrates belonging to the mollusca, echiuridea, insecta and crustacea. These peptides have been designated tachykinin-related peptides (TRPs) and are characterized by the preserved C-terminal pentapeptide FX1GX2Ramide (X1 and X2 are variable residues). All invertebrate TRPs are myostimulatory on insect hindgut muscle, but also have a variety of additional actions: they can induce contractions in cockroach foregut and oviduct and in moth heart muscle, trigger a motor rhythm in the crab stomatogastric ganglion, depolarize or hyperpolarize identified interneurons of locust and the snail Helix and induce release of adipokinetic hormone from the locust corpora cardiaca. Two putative TRP receptors have been cloned from Drosophila; both are G-protein coupled and expressed in the nervous system. The invertebrate TRPs are distributed in interneurons of the CNS of Limulus, crustaceans and insects. In the latter two groups TRPs are also present in the stomatogastric nervous system and in insects endocrine cells of the midgut display TRP-immunoreactivity. In arthropods the distribution of TRPs in neuronal processes of the brain displays similar patterns. Also in coelenterates, flatworms and molluscs TRPs have been demonstrated in neurons. The activity of different TRPs has been explored in several assays and it appears that an amidated C-terminal hexapeptide (or longer) is required for bioactivity. In many invertebrate assays the first generation substance P antagonist spantide I is a potent antagonist of invertebrate TRPs and substance P. Locustatachykinins stimulate adenylate cyclase in locust interneurons and glandular cells of the corpora cardiaca, but in other tissues the putative second messenger systems have not yet been identified. The heterologously expressed Drosophila TRP receptors coupled to the phospholipase C pathway and could induce elevations of inositol triphosphate. The structures, distributions and actions of TRPs in various invertebrates are compared and it is concluded that the TRPs are multifunctional peptides with targets both in the central and peripheral nervous system and other tissues, similar to vertebrate tachykinins. Invertebrate TRPs may also be involved in developmental processes.

Animals↗
PubMed2001

Cadmium accumulation in the freshwater isopod Asellus racovitzai: the relative importance of solute and particulate sources at trace concentrations.

A stable isotope tracer technique was used to evaluate the relative importance of particulates and water as respective sources of cadmium (Cd) uptake in the freshwater isopod Asellus racovitzai (Isopoda, Crustacea). 113Cd(NO3)2 was applied to the sediment at a nominal concentration of 20.0 ng g-1, and 114Cd(NO3)2 was added to the overlying water (nominal concentration of 4.4 ng g-1), in the same test systems. Asellids added were either free-ranging on the sediment surface, where they were exposed to both particulate and water sources of Cd, or were enclosed in dialysis 'tubes', 10 cm above the sediment surface, and were therefore exposed to Cd in water only. By analysis of both isotopes, uptake vectors could be determined simultaneously. After 7 days of exposure, average 114Cd concentrations in 'free' asellids were 15.6 +/- 2.0 micrograms/g, compared with 10.4 +/- 1.8 micrograms/g in 'tube'-held asellids (P < 0.05), i.e. at least 60% of accumulated 114Cd was from water. Furthermore, water-spiked 114Cd was accumulated in asellids to tissue concentrations that were more than four-times greater than sediment-spiked 113Cd. When the sediment organic content was increased (20% peat moss), total Cd concentrations in both overlying water and asellids were significantly lower (P < 0.01), compared with the mineral sediment treatments, and Cd accumulation in tube and free asellids was similar. This study shows that water is an important vector of Cd accumulation in A. racovitzai, and factors that lower Cd concentrations in solution (such as increased organic content of sediment), decrease Cd bioaccumulation.

Animals↗
PubMed1999

Subunit composition and N-terminal analysis of arthropod hemocyanins.

Fourteen structural subunits of hemocyanins from two different infraorders of crustacea, brachyura (Maia squinado, Carcinus maenas) and astacidea (Homarus americanus) were isolated and characterized. N-terminal amino acid sequences were determined and compared with known sequences of crustacean and cheliceratan hemocyanins. Relationships between the investigated polypeptide chains were established. The results demonstrate that the degree of identity, calculated from the amino terminal sequences, is lower than that determined from the complete sequences and can be used for reliable characterization of the whole individual subunits. Independent evolution is possible not only for members of different subphyla, but also for those from one infraorder or from the same hemocyanin.

Amino Acid Sequence↗
PubMed1999

Release of digestive enzymes from the crustacean hepatopancreas: effect of vertebrate gastrointestinal hormones.

Vertebrate gastrointestinal hormones were tested on their ability to liberate digestive enzymes from the crustacean midgut gland. CCK-8 (desulfated form), gastrin, bombesin, secretin, and substance P were detected to release enzymes. Maximal concentrations observed were 5 nM CCK for protease release, 1 nM gastrin for protease and 100 nM for amylase release, 100 nM bombesin for protease release, 10 nM secretin for amylase and protease release, and 100 nM substance P for protease release. Unlike in vertebrates, glucagon was unable to stimulate enzyme release in crustaceans, this also applies to the counterpart insulin. These results may support the assumption that Crustacea possess endogenous factors resembling the above mentioned vertebrate hormones, at least in such a way that the appropriate receptors have the capacity to accept these hormones.

Amylases↗
PubMed2000

Phylogenetic analysis of mitochondrial LSU rRNA in oniscids.

The phylogenetic relationships among oniscids (Crustacea, Isodopa) remain contradictory despite numerous morphological studies. We have investigated them using molecular data. Partial sequences of the mitochondrial LSU rRNA gene were obtained from 42 species of aquatic and terrestrial crustaceans from 31 genera. This gene provided well-supported information, notwithstanding the high taxonomic level of this study, indicating a useful amount of variation despite the noise due to multiple substitutions. The phylogenetic inferences demonstrated that a) Crinocheta and Synocheta sections are monophyletic and sister-groups, b) Ligiidae and Tylidae representatives are in a basal position compared to other oniscids, c) Helleria brevicornis, the only representative of the Helleriinae subfamily, has undergone different evolution, d) the relationships between aquatic isopods and ancient groups of Oniscidea are not resolved, probably due to fast radiation not discriminated by the molecular phylogeny.

Animals↗
PubMed2001

Influence of different essential and non-essential metals on MTLP levels in the Copepod Tigriopus brevicornis.

Because of their wide geographic distribution, position in the trophic chain, rapid turnover, huge biomass and role in ocean biogeochemical cycles, copepods are regarded as important marine test species. Tigriopus brevicornis Müller, 1776 is a shallow water benthic marine species (Crustacea, Copepoda Harpacticoida). The toxicity of essential and non-essential metals (Ag, Cd, Cu, Hg, Ni and Zn) to Tigriopus brevicornis was determined by 96-h LC(50) testing. Comparative crustacean 96-h LC(50) data in the literature show that Tigriopus brevicornis is a sensitive species suggesting that copepods are good indicators of minimal lethal concentrations of metals. Groups of 1000 to 1500 adult copepods were exposed for 1 to 14 days to metals at concentrations in water, 3 for each metal, considered realistic in comparison with those encountered in polluted environments and far below lethal concentrations, in order to avoid protein metabolism disturbance. The response of Tigriopus brevicornis in terms of MT induction has been examined in specimens exposed to metals. The induction of these proteins and their implication in detoxificatory mechanisms and trophic transfer are discussed.

Animals↗
PubMed2000

Richness patterns in the parasite communities of exotic poeciliid fishes.

Three species of poeciliids (Gambusia holbrooki, Xiphophorus helleri and X. maculatus) and 15 species of ecologically similar native freshwater fishes (mainly eleotrids, ambassids, melanotaeniids and retropinnids) were examined for parasite richness to investigate parasite flux, qualitative differences, quantitative differences and the structuring factors in parasite communities in the 2 fish types in Queensland, Australia. Theory suggests that poeciliids would harbour depauperate parasite communities. Results supported this hypothesis; poeciliids harboured more species-poor parasite infracommunities and regional faunas than natives (P < 0.0001), despite greater sampling effort for the former. Cluster analysis of presence/absence data for poeciliids and the 6 most-sampled native fishes revealed that parasite communities of the 2 fish groups are qualitatively distinct; the proportion of parasite species with complex life-cycles was lower in poeciliids than in native species, and Myxosporea, Microspora, Coccidia and parasitic Crustacea were all absent from poeciliids. Limited exchange of parasite species has occurred between natives and poeciliids. Logistic ordinal regression analysis revealed that fish origin (exotic or native), environmental disturbance and host sex were all significant determinants of parasite community richness (P < 0.05). Theoretical modelling suggests that poeciliids are at a competitive advantage over native fishes because of their lack of parasites.

Animals↗
PubMed2006

Thermal behaviour of crustaceans.

Specific thermoreceptors or putative multimodal thermoreceptors are not known in Crustacea. However, behavioural studies on thermal avoidance and preference and on the effects of temperature on motor activity indicate that the thermosensitivity of crustaceans may be in the range 0.2-2 degrees C. Work on planktonic crustaceans suggests that they respond particularly to changes in temperature by klinokinesis and orthokinesis. The thermal behaviour of crustaceans is modified by thermal acclimation among other factors. The acclimation of the critical maximum temperature is an example of resistance acclimation, while the acclimation of preference behaviour may be classified as capacity acclimation of some other function. In crustaceans, the use of the concepts stenothermy and eurythermy at the species level is questionable, and it is not possible to divide crustacean species into thermal guilds as suggested for fishes. Thermal preference behaviour contributes to fitness in different ways in different species, often by maximising the aerobic metabolic scope for activity. In crustaceans the peripheral nervous system seems to have retained the capacity for thermosensitivity and thermal acclimation independently of the central nervous system control of behaviour.

Acclimatization↗
PubMed2002

QSAR of ecotoxicological data on the basis of data-driven if-then-rules.

A rather small data matrix of seven chemicals and 17 different ecotoxicological end points is examined by methods of Discrete Mathematics. Especially, the lattice theory and its variant, the Formal Concept Analysis may be an attractive tool to analyze Quantitative Structure Activity Relationships, when a numerical functional approach is not at hand. The central item is the so called concept, which is a pair of subsets: A subset of molecules and a subset of properties which correspond to each other. The concepts are partially ordered due to a subset relation. From this subset relation, if-then-rules are derived, which aim to relate the structure of molecules with their ecotoxicological properties. For example, the following chemical rule is found: Cl --> (2A,2C,2M). That means, all substances considered here having a "-Cl" as structural code have a medium ecotoxicological effect on Daphnia magna, Orconectes immunisare (Crustacea) and on Photobacterium phosphoreum, at least within the training set.

Animals↗
PubMed2003

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). This unique phenomenon occurs in all Crustacea that use haemocyanin for oxygen transport. Molecular phylogeny analysis suggests the MnSOD gene duplication is as old as the origin of the arthropod phylum. cytMnSOD activity in the hepatopancreas changes during the moulting cycle of the crab. Activity is high in intermoult crabs and non-detectable in postmoult papershell crabs. mtMnSOD is present in all stages of the moulting cycle. Despite the lack of cytCu,ZnSOD, crabs have an extracellular Cu,ZnSOD (ecCu,ZnSOD) that is produced by haemocytes, and is part of a large, approx. 160 kDa, covalently-linked protein complex. ecCu,ZnSOD is absent from the hepatopancreas of intermoult crabs, but appears in this tissue at premoult. However, no ecCu,ZnSOD mRNA can be detected, suggesting that the protein is recruited from the haemolymph. Screening of different taxa of the arthropod phylum for Cu,ZnSOD activity shows that those crustaceans that use haemoglobin for oxygen transport have retained cytCu,ZnSOD. It appears, therefore, that the replacement of cytCu,ZnSOD with cytMnSOD is part of an adaptive response to the dynamic, haemocyanin-linked, fluctuations in copper metabolism that occur during the moulting cycle of the crab.

Amino Acid Sequence↗
PubMedDate not supplied

Expression of a homologue of the fushi tarazu (ftz) gene in a cirripede crustacean.

In Metazoa, Hox genes control the identity of the body parts along the anteroposterior axis. In addition to this homeotic function, these genes are characterized by two conserved features: They are clustered in the genome, and they contain a particular sequence, the homeobox, encoding a DNA-binding domain. Analysis of Hox homeobox sequences suggests that the Hox cluster emerged early in Metazoa and then underwent gene duplication events. In arthropods, the Hox cluster contains eight genes with a homeotic function and two other Hox-like genes, zerknullt (zen)/Hox3 and fushi tarazu (ftz). In insects, these two genes have lost their homeotic function but have acquired new functions in embryogenesis. In contrast, in chelicerates, these genes are expressed in a Hox-like pattern, which suggests that they have conserved their ancestral homeotic function. We describe here the characterization of Diva, the homologue of ftz in the cirripede crustacean Sacculina carcini. Diva is located in the Hox cluster, in the same position as the ftz genes of insects, and is not expressed in a Hox-like pattern. Instead, it is expressed exclusively in the central nervous system. Such a neurogenic expression of ftz has been also described in insects. This study, which provides the first information about the Hoxcluster in Crustacea, reveals that it may not be much smaller than the insect cluster. Study of the Diva expression pattern suggests that the arthropod ftz gene has lost its ancestral homeotic function after the divergence of the Crustacea/Hexapoda clade from other arthropod clades. In contrast, the function of ftz during neurogenesis is well conserved in insects and crustaceans.

Amino Acid Sequence↗
PubMedDate not supplied

[The life cycle of Microphallus gracilis Baer, 1943, a parasite of Neomys fodiens in the Pyrenees. Modalities of the transmission of the Digenea in nature (author's transl)].

Microphallus gracilis develops to the sporocyst stage in the digestive gland of the snail Bythinella reyniesii. The xiphidio-cercaria monostomous, anenterous in type, is liberated in water and actively penetrates a Crustacea Gammarus pulex where it encysts. From the point of view of the transmission ecology, the natural focuses of M. gracilis are composed of two different areas: an area where the parasite multiplies coinciding with biotope Bythinella and an area limited to the length of the river where the parasite spreads.

Animals↗
PubMedDate not supplied

[Metazoan parasites of Boops boops (Linnaeus, 1758) (Teleostean Sparidae) in the "Golfe du Lion", faunistic and ecology (author's transl)].

A global study of the Metazoan parasites of Boops boops (L., 1758) have been made in the "golfe du Lion". Fourteen different species (eight Platyhelmintha, one Nematoda and five Crustacea) have been inventorized. Their respective localisation on the hosts, globals and specifics corresponding prevalences as well as their variations according to the size of the fish, and their abundance have been precised. Parasitics associations have also been examined.

Animals↗