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PubMed2002

A DNA-based method for identification of krill species and its application to analysing the diet of marine vertebrate predators.

Accurate identification of species that are consumed by vertebrate predators is necessary for understanding marine food webs. Morphological methods for identifying prey components after consumption often fail to make accurate identifications of invertebrates because prey morphology becomes damaged during capture, ingestion and digestion. Another disadvantage of morphological methods for prey identification is that they often involve sampling procedures that are disruptive for the predator, such as stomach flushing or lethal collection. We have developed a DNA-based method for identifying species of krill (Crustacea: Malacostraca), an enormously abundant group of invertebrates that are directly consumed by many groups of marine vertebrates. The DNA-based approach allows identification of krill species present in samples of vertebrate stomach contents, vomit, and, more importantly, faeces. Utilizing samples of faeces from vertebrate predators minimizes the impact of dietary studies on the subject animals. We demonstrate our method first on samples of Adelie penguin (Pygoscelis adeliae) stomach contents, where DNA-based species identification can be confirmed by prey morphology. We then apply the method to faeces of Adelie penguins and to faeces of the endangered pygmy blue whale (Balaenoptera musculus brevicauda). In each of these cases, krill species consumed by the predators could be identified from their DNA present in faeces or stomach contents.

Animals↗
PubMed1993

[Contribution to the study of Microphallidae travassos, 1920 (Trematoda). XLV. Description of Maritrema feliui n. sp., parasite of shrews (Mammals) in Spain].

The authors describe and illustrate the morphology of the adult stage of Maritrema feliui n. sp. (Trematoda Microphallidae) obtained from the intestine of the shrew Crocidura russula (Hermann, 1780), definitive host of the fluke present in the estuary of the river Llobregat (Catalonia, Spain). The larval stages are found in two hosts obtained from the area: 1) Mercuria confusa (Frauenfeld) [= Pseudamnicola similis (Draparnaud)] (Mollusca: Hydrobiidae), and 2) Gammarus aequicauda (Martynov) (Crustacea: Amphipoda). The adult stage is anatomically related to the Maritrema with a mean size of the body, two equal suckers, a short oesophagus and long caeca, and a short and transversal cirrus pouch with a smooth and filiform cirrus. According to morphological and geographical affinities, the authors propose the synonymies of 1) Maritrema "opisthometra" sensu Bridgman et al., 1972 with M. chiriacae Deblock, 1975; 2) Maritrema longiforme Kifune et al., 1972, with Maritrema laricola Ching, 1963. Besides Maritreminoides congjiangensis Chiu et Gu, 1981 is transferred into the genus Quasimaritrema Deblock, 1973 according to Maritreminoides Rankin is invalidated.

Animals↗
PubMed2002

Molecular phylogenetic evidence for the independent evolutionary origin of an arthropod compound eye.

Eyes often take a central role in discussions of evolution, with debate focused on how often such complex organs might have evolved. One such debate is whether arthropod compound eyes are the product of single or multiple origins. Here we use molecular phylogeny to address this long-standing debate and find results favoring the multiple-origins hypothesis. Our analyses of DNA sequences encoding rRNA unequivocally indicate that myodocopids--the only Ostracoda (Crustacea) with compound eyes--are nested phylogenetically within several groups that lack compound eyes. With our well-supported phylogeny, standard maximum likelihood (ML) character reconstruction methods significantly reconstruct ancestral ostracods as lacking compound eyes. We also introduce a likelihood sensitivity analysis, and show that the single-origin hypothesis is not significantly favored unless we assume a highly asymmetric model of evolution (one favoring eye loss more than 30:1 over gain). These results illustrate exactly why arthropod compound eye evolution has remained controversial, because one of two seemingly very unlikely evolutionary histories must be true. Either compound eyes with detailed similarities evolved multiple times in different arthropod groups or compound eyes have been lost in a seemingly inordinate number of arthropod lineages.

Animals↗
PubMed2002

The molecular basis of the coloration mechanism in lobster shell: beta-crustacyanin at 3.2-A resolution.

The binding of the carotenoid astaxanthin (AXT) in the protein multimacromolecular complex crustacyanin (CR) is responsible for the blue coloration of lobster shell. The structural basis of the bathochromic shift mechanism has long been elusive. A change in color occurs from the orange red of the unbound dilute AXT (lambda(max) 472 nm in hexane), the well-known color of cooked lobster, to slate blue in the protein-bound live lobster state (lambda(max) 632 nm in CR). Intriguingly, extracted CR becomes red on dehydration and on rehydration goes back to blue. Recently, the innovative use of softer x-rays and xenon derivatization yielded the three-dimensional structure of the A(1) apoprotein subunit of CR, confirming it as a member of the lipocalin superfamily. That work provided the molecular replacement search model for a crystal form of the beta-CR holo complex, that is an A(1) with A(3) subunit assembly including two bound AXT molecules. We have thereby determined the structure of the A(3) molecule de novo. Lobster has clearly evolved an intricate structural mechanism for the coloration of its shell using AXT and a bathochromic shift. Blue/purple AXT proteins are ubiquitous among invertebrate marine animals, particularly the Crustacea. The three-dimensional structure of beta-CR has identified the protein contacts and structural alterations needed for the AXT color regulation mechanism.

Amino Acid Sequence↗
PubMed1993

Food allergy. Manifestations, evaluation, and management.

Allergic reactions to food are more common among infants and children but occur in adults as well. Foods that are most often implicated in allergic reactions are eggs, cow's milk, nuts, wheat, soy products, whitefish, and crustacea. Gastrointestinal, respiratory tract, and dermatologic symptoms, as well as systemic anaphylaxis, may develop. In addition to history taking and physical examination, the workup may include skin testing, the radioallergosorbent test, and double-blind oral food challenge. Avoidance of offending antigens is the most important aspect of treatment. If exposure occurs, antihistamines and epinephrine may be needed for treatment of an acute reaction.

Adult↗
PubMed2004

Novel source of semicarbazide: levels of semicarbazide in cooked crayfish samples determined by LC/MS/MS.

Nitrofuran antibiotics were previously used in animal healthcare but are now prohibited. Semicarbazide is a breakdown product of 5-nitrofurazone and protein-bound semicarbazide is used as a marker residue for the illegal use of 5-nitrofurazone. However, the presence of the prohibited semicarbazide has been reported in some food items of animal origin. A novel observation is reported that semicarbazide can be detected in Finnish crayfish samples, i.e. crustacea, never medicated with nitrofurazone. The origin of the semicarbazide is presently unknown. Positive identification was undertaken by liquid chromatography coupled with tandem mass spectrometry detection. The level of semicarbazide was determined as the protein-bound form as well as the total amount of semicarbazide in the sample. The average levels of total semicarbazide and the protein-bound form were 4.2 and 0.5 ng g(-1) fresh crayfish meat, respectively. All the tested samples (n = 18) contained traces of semicarbazide, the highest amount being 12 ng g(-1) fresh crayfish meat.

Animals↗
PubMedDate not supplied

Lead, cadmium and mercury contents in average Spanish market basket diets from Galicia, Valencia, Andalucía and Madrid.

This study was undertaken in order to monitor the intake of lead, cadmium and mercury in different geographical areas of Spain. The intakes of four populations were estimated from their habitual diets and compared with the Provisional Tolerable Weekly Intake (PTWI) or the Acceptable Daily Intake (ADI) to estimate the health risk of toxicity. Representative market basket diets from four areas, Galicia, Valencia, Andalucía and Madrid, were collected and their contents of cadmium, lead and mercury determined. The number of different foodstuffs used in each area (64, 67, 71 and 73) was based on the number of foods providing 95% of the total energy intake. Data on the contribution of food groups to the total daily intake of heavy metals were also obtained. The daily amounts of lead in the diets were between 37 and 521 micrograms/day, the Madrid population having the highest average intake of this metal and exceeding the PTWI, because of the vegetables and cereals consumed. The average total dietary cadmium intakes--provided mainly by fish including crustacea and molluscs--were about 25-45% of the PTWI. The intake of mercury, which is mainly provided by the fish group (66-90%), was about 9-17% of the PTWI.

Cadmium↗
PubMedDate not supplied

Aspergillus flavus-induced chitosanase in germinating corn and peanut seeds: A. flavus mechanism for growth dominance over associated fungi and concomitant aflatoxin production.

Chitosanase, a new class of enzymes with antifungal properties was induced by toxigenic Aspergillus flavus in both germinating corn and peanut seeds. The enzyme was partially purified and fractioned by SDS-Polyacrylamide Gel Electrophoresis activity and copolymerized with chitosan or glycolchitosan as substrate, then quantified by scanning densitometry and a 2-dimensional analysis software program. Chitosanase enzyme was markedly induced by toxigenic A. flavus growing in germinating corn and peanut seeds, as compared to control (water) which showed the lowest activity (almost nil in corn). However, chitosanase induction was higher in seeds treated with chitosan from crustacea. Overall, enzyme activity was higher in peanut than in corn seeds. However, electrophoresed gels from peanut treated with A. flavus or water showed more polypeptides (three and one, respectively) than gels from corn seeds, which only showed one polypeptide for both A. flavus and water treatment. The enzyme molecular weight was estimated to be between 36,000 and 45,000.

Aflatoxins↗
PubMed2004

Recruitment in the field of Balanus improvisus and Mytilus edulis in response to the antifouling cyclopeptides barettin and 8,9-dihydrobarettin from the marine sponge Geodia barretti.

In this field investigation the two cyclopeptides, isolated from the marine sponge Geodia barretti Bowerbank (Geodiidae, Astrophorida), are shown to be very efficient in preventing recruitment of the barnacle Balanus improvisus (Cirripedia, Crustacea) and the blue mussel Mytilis edulis (Protobranchia, Lamellibranchia) when included in different marine paints. These brominated cyclopeptides, named barettin and 8,9-dihydrobarettin were incorporated in different non-toxic coatings. The substances were used in the concentrations 0.1 and 0.01% in all treatments. The most efficient paint was a SPC polymer. This paint, in combination with barettin and 8,9-dihydrobarettin, reduced the recruitment of B. improvisus by 89% (barettin, 0.1%) and by 67% (8,9-dihydrobarettin, 0.1%) as compared to control panels. For M. edulis, the reduction of recruitment was 81% with barettin (0.1%) and 72% with 8,9-dihydrobarettin (0.1%) included in the SPC paint. This indicates that the two compounds from G. barretti could provide non-toxic alternatives as additives in antifouling paints, since the heavy metal-based marine paints are to be replaced.

Animals↗
PubMed2005

Larval development and post-settlement metamorphosis of the barnacle Balanus albicostatus Pilsbry and the serpulid polychaete Pomatoleios kraussii Baird: Impact of a commonly used antifouling biocide, Irgarol 1051.

AbstractThe impact of a commonly-used antifouling algicide, Irgarol 1051, on the larval development and post-settlement metamorphosis of the barnacle, Balanus albicostatus Pilsbry (Crustacea: Cirripedia), and the larval metamorphosis of a serpulid polycheate, Pomatoleios kraussii Baird, was evaluated. In the case of B. albicostatus, larval mortality increased with an increase in the concentration of Irgarol 1051, and there was a shift in the larval stage targeted from advanced instars to early instars. Nauplii that survived to the cyprid instar stage when reared in the presence of Irgarol 1051 showed prolonged instar and total naupliar duration when compared to the controls. The post-settlement metamorphosis of cyprids significantly varied with Irgarol concentration and also with biofilm age. One and 2-d-old untreated biofilms showed higher metamorphosis when compared to 5-d-old biofilms. However, when the biofilms that promoted cyprid metamorphosis were treated with Irgarol 1051 at low concentrations, metamorphosis rates decreased. Cyprids were prevented from metamorphosing completely by biofilms treated at the highest concentration of Irgarol 1051. Inhibition of metamorphosis was also observed in the case of competent polychaete larvae when exposed to Irgarol 1051 compared to those exposed to metamorphosis inducers such as 3-iso-butyl-1-methylxanthine (IBMX) and natural biofilms. Identification of the pathway(s) that caused the promotory biofilms to become toxic when exposed to Irgarol 1051 is discussed.

1-Methyl-3-isobutylxanthine↗
PubMed2005

Evidence for multiple reversals of asymmetric mutational constraints during the evolution of the mitochondrial genome of metazoa, and consequences for phylogenetic inferences.

Mitochondrial DNA (mtDNA) sequences are comonly used for inferring phylogenetic relationships. However, the strand-specific bias in the nucleotide composition of the mtDNA, which is thought to reflect assymetric mutational constraints, combined with the important compositional heterogeneity among taxa, are known to be highly problematic for phylogenetic analyses. Here, nucleotide composition was compared across 49 species of Metazoa (34 arthropods, 2 annelids, 2 molluscs, and 11 deuterosomes), and analyzed for a mtDNA fragment including six protein-coding genes, i.e., atp6, atp8, cox1, cox2, cox3, and nad2. The analyses show that most metazoan species present a clear strand assymetry, where one strand is biased in favor of A and C, whereas the other strand has reverse bias, i.e. in favor of T and G. the origin of this strand bias can be related to assymetric mutational constraints involving deaminations of A and C nucleotides during the replication and/or transcription processes. The analyses reveal that six unrelated genera are characterized by a reversal of the usual strand bias, i.e., Argiope (Araneae), Euscorpius (Scorpiones), Tigrioupus (Maxillopoda), Branchiostoma (Cephalochordata) Florometra (Echinodermata), and Katharina (Mollusca). It is proposed that assymetric mutational constraints have been independantly reversed in these six genera, through an inversion of the control region, i.e., the region that contains most regulatory elements for replication and transcription of the mtDNA. We show that reversals of assymetric mutational constraints have dramatic consequences on the phylogenetic analyses, as taxa characterized by reverse strand bias tend to group together due to long-branch attraction artifacts. We propose a new method for limiting this specific problem in tree reconstruction under the Bayesian approach. We apply our method to deal with the question of phylogenetic relationships of the major lineages of Arthropoda, This new approach provides a better congruence with nuclear analyses based on mtDNA sequences, our data suggest that Chelicerata, Crustacea, Myriapoda, Pancrustacea, and Paradoxopoda are monophyletic.

Animals↗
PubMedDate not supplied

Physiology of immunity in the water flea Daphnia magna: environmental and genetic aspects of phenoloxidase activity.

In an attempt to understand the ecological correlates of immunocompetence in Daphnia magna (Crustacea, Cladocera), we tested for variation in immune function in relation to feeding conditions, host conditions, and host genotype. We investigated both phenotypic (environmental dependent and condition dependent) as well as genotypic aspects of the prophenoloxidase activating system (Pro-POAS), which has been described as a key factor in invertebrate immunity. Daphnia magna is an ideal study system to disentangle phenotypic and genetic variation because females can reproduce clonally. Well-fed Daphnia showed higher phenoloxidase (PO) activity than Daphnia kept at a low food level. Wounding provoked a higher level of PO activity, indicating that the Pro-POAS was condition dependent. Further, we found clonal variation in PO activity among four clones of D. magna isolated from four different populations. The same four clones were tested for their resistance to the bacterial pathogen Pasteuria ramosa. High resistance corresponded to high PO activity. Our results suggest adaptive variation in PO activity and suggest that its expression is costly. These costs may influence the evolution of the PO activity level and the maintenance of its genotypic variation.

Animals↗
PubMedDate not supplied

Diurnal variation and effects of feeding on blood glucose in the giant tiger prawn, Penaeus monodon.

Previous studies on crustacea have demonstrated significant diurnal rhythms in blood glucose. However, glucose concentration in the blood of food-deprived Penaeus monodon, held in indoor or outdoor tanks, did not exhibit a diurnal rhythm under photoperiods of 8 h light and 16 h darkness (8L: 16D) or under a 13.5L: 9.5D photoperiod, with simulated or natural full moon conditions. Prawns held on photoperiods of constant light, 20L : 4D, 16L : 8D, 12L : 12D, 8L : 16D, 4L : 20D, or continuous darkness did not have significantly different mean blood glucose levels. Mean blood glucose levels varied between 0.77 and 1.39 mmol/L, depending on conditions. Pronounced and significant increases in blood glucose levels occurred within 20 min of feeding, with peak levels after 100 min. The rise in blood glucose level observed after feeding was independent of the eyestalks, and hence putative crustacean hyperglycaemic hormone, and was not from endogenous carbohydrate stores. Under appropriately controlled conditions, blood glucose concentrations can be used as an index of nutritional status in penaeid prawns.

Animals↗
PubMed1979

Enzyme polymorphism and cyclic parthenogenesis in Daphnia magna. I. Selection and clonal diversity.

Genotype frequencies and fecundities were recorded over a period of two years for three polymorphic enzyme loci (Est, Mdh and Got) in a parthenogenetic natural population of Daphnia magna Straus (Crustacea: Cladocera). There was a large excess of heterozygotes at each locus, and some nonrandom association between loci, although 29 different three-locus genotypes were detected. There were small but significant changes in genotype frequencies that did not follow any clear seasonal cycles or overall trends, and the genotypes often differed significantly in fecundity, although the direction of the difference was not constant. These fitness differences were probably not attributable to the specific loci studied.--Models of balancing selection are of two types: segregation-balanced (e.g., heterosis) and competition-balanced (e.g., frequency dependence). Only the latter type can stabilize diversity in a clonal population. The observed selection was not heterotic, but it is not certain that it was stabilizing either. Clonal competition did not lead to victory by a single, fittest clone; genotypic diversity remained high.

Animals↗
PubMed1979

Enzyme polymorphism and cyclic parthenogenesis in Daphnia magna. II. Heterosis following sexual reproduction.

Cyclical parthenogenesis exaggerates the force of selection relative to recombination and will therefore enhance interlocus effects. Observations of electrophoretic variation in a natural population of Daphnia magna Straus (Crustacea: Cladocera) are interpreted in this light. Sexual reproduction led to Hardy-Weinberg equilibrium, but heterozygote excesses rapidly developed at each of three observed loci during subsequent parthenogenesis. Homozygote fecundity was often lower than that of heterozygotes; this may have been the cause of some of the observed frequency changes. The superior fitness of the enzyme heterozygotes does not imply that selection was necessarily acting on the enzyme loci thermselves, since apparent heterosis is the expected result of linkage disequilibrium.

Animals↗
PubMedDate not supplied

Disparity in population differentiation of sex-linked and autosomal variation in sibling species of the Jaera albifrons (Isopoda) complex.

The genetic variation at four enzyme loci is described for 22 populations of three Jaera species--J. albifrons, J. ischiosetosa, and J. praehirsuta--in the J. albifrons complex (Crustacea, Isopoda) in Denmark. The variation at three of the loci is similar, with the allele frequency spectra close to each other in all three species. An evolutionary tree based on the variation at these three loci revealed that the populations from the different species are completely intermixed in the tree. This was supported by hierarchical F-statistics where the between-species component was zero. At a fourth locus, Gpi (glucose phosphate isomerase), the species differ substantially. This locus is sex linked in J. ischiosetosa, but in the two other species, J. albifrons and J. praehirsuta, it is either found on autosomes or is sex linked with a high recombination rate between the locus and the centromere. An evolutionary tree for this locus partitions the populations into separate groups and a hierarchical F-statistic has a between-species component of about 50%. The results are attributed to introgression with a higher rate for autosomes than for sex chromosomes.

Animals↗
PubMed1990

Tissue specificity of tropomyosin from the crayfish, Cambarus clarki.

The molecular heterogeneity and tissue specificity of crustacean tropomyosin were investigated, using muscle and nonmuscle tissues from the crayfish, Cambarus clarki. In muscle, three types of tropomyosin isoforms were found on two-dimensional gel electrophoresis. One of them was specific to cardiac muscle, and the other two were shared by skeletal and visceral muscles. In nonmuscle tissues, four types of isoforms were found on two-dimensional gel electrophoresis and in immunoreplica tests using an antiserum against crayfish skeletal muscle tropomyosin. Two of them were common to the muscle isoforms, but the other two were not detected in muscles. Furthermore, nonmuscle tissues contained several peculiar isoforms, the electrophoretic mobilities of which were considerably higher than those of the other isoforms mentioned above. When tropomyosin was purified from the mid-gut gland, these isoforms with high mobilities were found in the crude tropomyosin preparation. These results showed that the crayfish tropomyosin was heterogeneous and that the isoforms were distributed in a tissue-specific manner, like vertebrate tropomyosin. However, the results did not coincide with those of our previous study on horseshoe crab tropomyosin, which showed molecular heterogeneity but no tissue specificity. In view of the difference in the isoform distributions between the two major groups (Crustacea and Merostomata) of Arthropoda, the significance of the tissue specificity of tropomyosin isoforms was discussed.

Animals↗
PubMed2001

Diplopod hemocyanin sequence and the phylogenetic position of the Myriapoda.

Hemocyanins are copper-containing respiratory proteins of the Arthropoda that have so far been thoroughly investigated only in the Chelicerata and the Crustacea but have remained unstudied until now in the Myriapoda. Here we report the first sequence of a myriapod hemocyanin. The hemocyanin of Spirostreptus sp. (Diplopoda: Spirostreptidae) is composed of two distinct subunits that are arranged in a 6 x 6 native molecule. The cloned hemocyanin subunit cDNA codes of for a polypeptide of 653 amino acids (75.5 kDa) that includes a signal peptide of 18 amino acids. The sequence closely resembles that of the chelicerate hemocyanins. Molecular phylogenetic analyses reject with high statistical confidence the integrity of the Tracheata (i.e., Myriapoda + Insecta) but give conflicting results on the position of the myriapod hemocyanin. While distance matrix and maximum-likelihood methods support a basal position of the Spirostreptus hemocyanin with respect to the other hemocyanins, parsimony analysis suggests a sister group relationship with the chelicerate hemocyanins. The latter topology is also supported by a unique shared deletion of an alpha-helix. A common ancestry of Myriapoda and Chelicerata should be seriously considered.

Amino Acid Sequence↗