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At least 649 records · Page 36Linked to original sources
PubMed1989

Structural analysis of the uEGF gene in the sea urchin strongylocentrotus purpuratus reveals more similarity to vertebrate than to invertebrate genes with EGF-like repeats.

The gene uEGF, a member of the epidermal growth factor family in the sea urchin Stronglyocentrotus purpuratus, is known to express two transcripts that are regulated developmentally in the embryo. We have partially sequenced several uEGF genomic and cDNA clones. We suggest that the smaller transcript is the result of splicing out an internal region present in the larger mRNA, probably with eight EGF-like repeats. The predicted two uEGF products have a signal peptide followed by an EGF-like repeat and a region with approximately 120 amino acids homologous to domain III in complement component C1s. Following these domains, the short product has 12 tandem EGF-like repeats, whereas the long product has approximately 20 tandem repeats. At the carboxy terminus both products have a region homologous to avidin. Unlike Notch and lin-12, no transmembrane domain was found in uEGF. We also show here that uEGF shares two characteristics with vertebrate members of the EGF family, but not with invertebrate members of the same family. (1) All the EGF-like domains sequenced are represented by single exons. (2) All the introns sequenced follow the first nucleotide of a codon. This supports the hypothesis that the organization of the EGF-like domains in vertebrates and in uEGF derived from a common ancestor. Thus, an alternative molecular datum is provided to support the hypothesis of echinoderm-chordate relationships.

Amino Acid Sequence↗
PubMed1996

Genetic analysis of cholinergic nerve terminal function in invertebrates.

Genetic analysis of nerve terminal function is proving fruitful and studies on invertebrates are making a substantial impact. In this survey, particular emphasis has been placed on cholinergic chemical synaptic transmission. The advanced genetics of Drosophila melanogaster and Caenorhabditis elegans with their rich diversity of behavioural and biochemical mutants is providing new insights into the functions of key molecular components of synapses. A 'space-invader' mutant of Periplaneta americana permits investigations of competition between neurons during synaptogenesis and its impact on neurotransmitter release. The growing importance of the C. elegans genome as a major research resource is emphasized in this survey.

Acetylcholine↗
PubMed2000

Collagenolytic protease preparations from invertebrates: experimental study of acute and chronic toxicity.

Toxicity of active matter of new structure-destroying enzyme preparations containing a complex of collagenolytic proteases from invertebrates (Collagenase from hydrobionts, Polycollagenase-K, Fermenkol) was studied. The absence of acute toxicity in skin application is proved, and LD(50) for intraperitoneal administration to mice and rats were determined. A long-term treatment with clinical doses under various types of application does not affect body weight gain, biochemical indices of the plasma, ECG, diuresis, and urine content.

Animals↗
PubMedDate not supplied

Alzheimer's drug design based upon an invertebrate toxin (anabaseine) which is a potent nicotinic receptor agonist.

Naturally occurring toxins can often serve as useful chemical tools for investigating signalling processes in nervous and other systems. Tetrodotoxin and alpha-bungarotoxin are prime examples of toxins which are widely used in neurobiological research. Some toxins may also become molecular models for designing new drugs. Usually drugs are small, non-peptide molecules, as these display better bioavailability, longer durations of action and are less likely to generate immune responses. The relatively large size and conformational flexibility of peptides and protein toxins makes them more challenging molecular models for rational drug design. This article considers a marine invertebrate toxin, anabaseine, and describes how manipulation of the structure of this alkaloid has provided a drug candidate which selectively stimulates mammalian brain alpha7 nicotinic receptors. Numerous anabaseine analogs were synthesized and subjected to a variety of pharmacological, behavioral and toxcicological tests. This led to the choice of GTS-21 (also known as 3-(2,4-dimethoxybenzylidene)-anabaseine or DMXBA), as a drug candidate for the treatment of Alzheimer's dementia. The chemical and pharmacological properties of GTS-21 are compared with those of the initial lead compound, anabaseine.

Alzheimer Disease↗
PubMed2003

Urochordates carry multiple genes for goose-type lysozyme and no genes for chicken- or invertebrate-type lysozymes.

Genome clones and expressed sequence tags (ESTs) from the ascidian Ciona intestinalis and from the larvacean Oikopleura dioica were analysed for the presence of lysozyme-encoding genes. Two genes were found to potentially code for goose-type lysozymes in Oikopleura, while three or possibly more g-type proteins form the lysozyme complement of C. intestinalis, and at least one of these genes from each species is expressed based on EST data. No genes for chicken- or invertebrate-type lysozymes were found in either urochordate species. Consistent with this finding, extracts of Oikopleura animals possessed hydrolysing activity on bacterial cell walls, and this activity was not inhibited in the presence of a known inhibitor of chicken-type lysozyme. A wide range of isoelectric points for the predicted lysozymes from Ciona (pI 4.4, 6.4 and 9.9) and from Oikopleura (pI 5.0 and 8.0) suggests tissue-specific adaptations as well as specific functional roles of the lysozymes. Comparisons of gene structures, encoded sequences, cysteine residue content and their positions in the proteins indicate that the g-type lysozymes of Ciona intestinalis are more closely related to those of vertebrates than are the g-type lysozymes of Oikopleura. Multiple genes from each species may result from separate and lineage-specific duplications followed by functional specialisation.

Amino Acid Sequence↗
PubMed1999

JAKs and STATs in invertebrate model organisms.

Invertebrate organisms provide systems to elucidate the developmental roles of Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling pathways, thereby complementing research conducted with mammalian cells and animals. Components of the JAK/STAT protein pathway have been identified and characterized in the fruit fly Drosophila melanogaster and the cellular slime mold Dictyostelium discoideum. This review summarizes the molecular and genetic data obtained from these model organisms. In particular, a Drosophila JAK/STAT pathway regulates normal segmentation, cell proliferation, and differentiation, and hyperactivation of the pathway leads to tumor formation and leukemia-like defects. A Dictyostelium STAT regulates the development of stalk cells during the multicellular part of the life cycle. Future research utilizing these organisms should continue to provide insights into the roles and regulation of these proteins and their signaling pathways.

Animals↗
PubMed2006

Driving forces from soil invertebrates to ecosystem functioning: the allometric perspective.

The European soil policy is being focussed towards a more conscious and sustainable use of the soil, taking into account ecological, economical and societal dimensions. Living soil organisms are reliable bioindicators, as they provide the best reflection of the soil system, ecological services and ecosystem functioning therein. These most complex (bio)physical systems indicate, among others, the energy flow. Such processes can be described by rather simple power law relationships. In fact, the average body mass (dry weight) can be seen as an inherent species property, while population density is a much more flexible parameter reflecting ecosystem state. In this study, I review the interactions between these items in relation to feedbacks and conjectured relationships which can be seen as ecological networks. From this novel perspective, allometry can be used as an integrated measure for the anthropogenic influence on landscapes and related food webs. Allometry is, therefore, a perfect surrogate for land use intensity in modelling of field effects for restoration ecology and conservation biology. Robust correlations will be addressed between the density dependence of invertebrates and the ability of soil systems themselves to recover after disturbance. Quantitative indicators of soil community composition and related ecological services are proposed and their application for ecological risk assessment is illustrated.

Animals↗
PubMed2002

Phylogenetic analysis of invertebrate lysozymes and the evolution of lysozyme function.

We isolated and sequenced the cDNAs coding for lysozymes of six bivalve species. Alignment and phylogenetic analysis showed that, together with recently described bivalve lysozymes, the leech destabilase, and a number of putative proteins from extensive genomic and cDNA analyses, they belong to the invertebrate type of lysozymes (i type), first described by Jollès and Jollès (1975). We determined the genomic structure of the gene encoding the lysozyme of Mytilus edulis, the common mussel. We provide evidence that the central exon of this gene is homologous to the second exon of the chicken lysozyme gene, belonging to the c type. We propose that the origin of this domain can be traced back in evolution to the origin of bilaterian animals. Phylogenetic analysis suggests that i-type proteins form a monophyletic family.

Amino Acid Sequence↗
PubMed2003

Gene fishing: the use of a simple protocol to isolate multiple homeodomain classes from diverse invertebrate taxa.

Comparison of relevant gene sequence and functional data is central to understanding the evolution of metazoan development. The conservation of portions of regulatory genes, such as homeoboxes, allows for the design of PCR-based sequence isolation and amplification strategies. Here we describe a simple protocol that uses a degenerate primer pair to isolate a variety of homeobox-containing genes from diverse metazoan taxa. In a nonexhaustive survey, we have isolated 28 gene sequence fragments from 15 taxa, representing eight invertebrate phyla (Mollusca, Echiura, Annelida, Platyhelminth, Acoela, Ctenophora, Cnidaria, and Porifera). Based on BLAST and parsimony analyses, these gene fragments affiliate with several gene groups (PAIRED-like, HOX, and ParaHOX) and several single genes, including pancreas/duodenum homeoboxes (Pdx), empty spiracles (ems/Emx), gastrulation brain homeoboxes (Gbx), hematopoietically expressed homeoboxes (HEX), brain specific homeobox (bsh/BarH1/BarH2), NK-1 (NK-1/s59/slouch), and ladybird (Lbl/Lbe/Lbx). In several cases, these fragments represent the first reported orthologue for the phylum or superphyletic group (i.e., Lophotrochozoa).

Amino Acid Sequence↗
PubMed2004

Comparison of laboratory single species and field population-level effects of the pyrethroid insecticide lambda-cyhalothrin on freshwater invertebrates.

The toxicity of the pyrethroid insecticide lambda-cyhalothrin to freshwater invertebrates has been investigated using data from short-term laboratory toxicity tests and in situ bioassays and population-level effects in field microcosms. In laboratory tests, patterns of toxicity were consistent with previous data on pyrethroids. The midge Chaoborus obscuripes was most sensitive (48- and 96-h EC50 = 2.8 ng/L). Other insect larvae (Hemiptera, Ephemeroptera) and macrocrustacea (Amphipoda, Isopoda) were also relatively sensitive, with 48- and 96-h EC50 values between 10 and 100 ng/L. Generally, microcrustacea (Cladocera, Copepoda) and larvae of certain insect groups (Odonata and Chironomidae) were less sensitive, with 48-h EC50 values higher than 100 ng/L. Mollusca and Plathelminthes were insensitive and were unaffected at concentrations at and above the water solubility (5 microg/L). Generally, the EC50 values based on initial population responses in field enclosures were similar to values derived from laboratory tests with the same taxa. Also, the corresponding fifth and tenth percentile hazard concentrations (HC5 and HC10) were similar (laboratory HC5 = 2.7 ng/L and field HC5 = 4.1 ng/L; laboratory and field HC10 = 5.1 ng/L), at least when based on the same sensitive taxonomic groups (insects and crustaceans) and when a similar concentration range was taken into account. In the three field enclosure experiments and at a treatment level of 10 ng/L, consistent effects were observed for only one population (Chaoborus obscuripes), with recovery taking place within 3 to 6 weeks. The laboratory HC5 (2.7 ng/L) and HC10 (5.1 ng/L) based on acute EC50 values of all aquatic arthropod taxa were both lower than this 10 ng/L, a concentration that might represent the "regulatory acceptable concentration." The HC5 and HC10 values in this study in The Netherlands (based on static laboratory tests with freshwater arthropods) were very similar to those derived from a previous study in the United Kingdom (1.4 and 3.3 ng/L). This suggests that for pesticides like lambda-cyhalothrin, HC5 values based on static laboratory tests may provide a conservative estimate of the potential for community-level effects under field conditions. While these HC5 values are conservative for initial effects, they do not provide information on recovery potential, which may be important for regulatory decision-making.

Animals↗
PubMed1999

Polychlorinated biphenyl- and mercury-associated alterations on benthic invertebrate community structure in a contaminated salt marsh in southeast Georgia.

The community structure of a benthic macroinvertebrate assemblage in a contaminated salt marsh was evaluated as part of an ecological characterization of a former chloralkali production facility in Georgia. Sample locations were chosen based on a gradient of the primary contaminants of concern, total mercury and polychlorinated biphenyls (PCBs), primarily Aroclor 1268. Sediment concentrations of Aroclor 1268 ranged from 2.3 to 150 mg/kg dry weight, while mercury concentrations ranged from 15 to 170 mg/kg dry weight in the study area. Mercury and PCBs were determined to be co-located in the sediments. Total organic carbon composition of the sediments was negatively associated with PCB and mercury concentrations. A total of 29 benthic taxa was identified in 49 samples; replicate samples were taken at each of five sampling locations. Mean infaunal density across all sampling locations was estimated at approximately 61,000 to 234,000 organisms m(-2). Overall, polychaetes comprised 57% of the infaunal community with Manayunkia aestuarina as the dominant species. Oligochaetes, nematodes, crustacea, insects, and gastropods comprised 23.0, 18.0, 1.0, 0.7, and 0.2% of the overall benthic community, respectively. Density estimates of individual species between sampling locations showed no consistent patterns in response to pollutants. However, an analysis of higher taxonomic levels revealed some general trends. In uncontaminated areas, the benthic community was dominated by nematodes and oligochaetes, whereas moderate to highly contaminated areas were dominated by polychaetes and a smaller percentage of oligochaetes and nematodes. A trophic analysis of the same data set revealed that the community shifted from an evenly distributed percentage of surface and subsurface feeders in the uncontaminated areas to a community dominated by surface feeders in the more contaminated locations. Carnivores comprised from 0.13 to 0.90% of the trophic structure, with the percentage of carnivores generally decreasing with increasing contamination. Mercury and PCBs were bioaccumulating in representative marsh benthic invertebrates, presenting a potential source of contaminants to marsh consumers. Tissue PCB and tissue mercury concentrations were positively related to sediment PCB and mercury concentrations, respectively. A standard 14-day toxicity test using the amphipod Leptocheirus plumulosus showed no acute toxicity across the sampling locations.

Animals↗
PubMed2000

Factors controlling the bioaccumulation of mercury, methylmercury, arsenic, selenium, and cadmium by freshwater invertebrates and fish.

Concentrations of mercury (Hg), methylmercury (MMHg), arsenic (As), selenium (Se), and cadmium (Cd) were measured in atmospheric deposition, stream water, and biota in two streams in western Maryland. Overall, concentrations were slightly higher in the water of the lower pH Herrington Creek tributary (HRCT). Bioaccumulation factors were also higher for HRCT compared to Blacklick Run (BLK). MMHg concentrations in biota increased with trophic level and essentially all the Hg was as MMHg in predatory insects and insectivorous/carnivorous fish. Thus, the overall trophic status of the organism was indicated by the %MMHg in its tissues. Levels of As, Se, Cd, and Hg, however, decreased with increasing trophic level. Adsorption of As to the exoskeleton of invertebrates appears to be an important accumulation mechanism. MMHg was distributed evenly throughout crayfish and fish organs, whereas As, Se, Cd, and Hg were found in higher concentrations in detoxifying organs. Concentrations in biota in this study were somewhat elevated compared to other rural sites, but were less than those of point source-contaminated sites. Overall, as atmospheric inputs to the two watersheds were similar, the results of this study show the importance of water chemistry in determining the bioaccumulation of the metals and metalloids into insects. Subsequent transfer to higher trophic levels is related to both the ability of the organisms to depurate and the mode of accumulation, either directly from water or from food.

Animals↗
PubMed2002

Microscale evaluation of the effects of grazing by invertebrates with contrasting feeding modes on river biofilm architecture and composition.

River biofilms are a valuable food resource for many invertebrates. In the present study biofilms were cultivated in a rotating annular bioreactor with river water as sole source of inoculum. The resulting biofilms were then presented to starved snails, ostracods, and mayflies as sole food source. The biofilms were then removed and microscopically examined to determine areas that had been grazed. The grazed and ungrazed areas were marked and analyzed for the effects of grazing using confocal laser scanning microscopy and image analyses. Samples were treated with fluorescent probes for nucleic acids to quantify bacterial biomass and fluor-conjugated lectins to quantify exopolymer, and far red autofluorescence was imaged to quantify algal or photosynthetic biomass. Grazing by snails significantly reduced algal biomass (1.1 +/- 0.6 micro m 3 micro m 2 to 0.02 +/- 0.04 micro m 3 micro m 2), exopolymer (5.3 +/- 3.4 micro m 3 micro m 2 to 0.18 +/- 0.18 micro m 3 micro m 2), and biofilm thickness (154 micro m +/- 50 to 11 micro m +/- 5.2; ANOVA, p < or= 0.05). Although bacterial biomass was influenced by grazing snails the impact was not statistically significant (p <or= 0.05). Ostracods had a significant (p <or= 0.05) impact on the algal biomass and exopolymer but not on bacteria. Mayfly grazing resulted in reduction of biofilm thickness to approximately 40 mm and reductions in all biofilm components with little evidence of selectivity. Thus grazing consistently resulted in a significant reduction in autotrophic biomass and exopolymer with a resultant increased importance of bacterial biomass within the grazed regions. Examination of grazed biofilms after a recovery period in the absence of grazing indicated that grazed regions remained predominantly bacterial after 28 days. A comparison of grazing in diclofop methyl and atrazine contaminated (1 ppb and 10 ppb) versus control biofilms indicated no significant influence of the contaminants on grazing patterns.

Animals↗
PubMedDate not supplied

Platelet aggregation inhibitors from Philippine marine invertebrate samples screened in a new microplate assay.

A new microplate assay for Ca(2+)-induced platelet aggregation as detected by Giemsa dye was used to screen marine invertebrate samples from the Philippines for inhibitors of human platelet aggregation. Out of 261 crude methanol extracts of marine sponges and tunicates, 25 inhibited aggregation at 2 mg/ml. Inhibition of agonist-induced aggregation in an aggregometer was used to confirm results of the microplate assay and to determine the specific mode of inhibition of 2 samples. The marine sponge Xestospongia sp. yielded a xestospongin/araguspongine-type molecule that inhibited collagen-induced aggregation by 87% at 2 micro g/ml, and epinephrine-induced aggregation by 78% at 20 micro g/ml, while the marine sponge Aplysina sp. yielded 5,6-dibromotryptamine, which inhibited epinephrine-induced aggregation by 51% at 20 micro g/ml. In this study we have found that the microplate assay is a simple, inexpensive, yet useful preliminary tool to qualitatively screen a large number of marine samples for antiplatelet aggregation activity.

Adenosine Diphosphate↗
PubMed2005

Toxicity of organic compounds to marine invertebrate embryos and larvae: a comparison between the sea urchin embryogenesis bioassay and alternative test species.

This study investigated the toxic effects of the insecticides lindane and chlorpyrifos, the herbicide diuron, the organometallic antifoulant tributyltin (TBT), and the surfactant sodium dodecyl sulfate (SDS) on the early life stages of Paracentrotus lividus (Echinodermata, Euechinoidea), Ciona intestinalis (Chordata, Ascidiacea), Maja squinado and Palaemon serratus (Arthropoda, Crustacea) in laboratory acute toxicity tests. The assays studied embryogenesis success from fertilized egg to normal larvae in P. lividus (48 h incubation at 20 degrees C) and C. intestinalis (24 h incubation at 20 degrees C), and larval mortality at 24 and 48 h in M. squinado and P. serratus. For P. lividus, the median effective concentrations (EC50) reducing percentages of normal larvae by 50% were: 350 microg l(-1) for chlorpyrifos, 5500 microg l(-1) for diuron, 4277 microg l(-1) for SDS, and 0.309 microg l(-1) for TBT. For C. intestinalis, the EC50 values affecting embryogenesis success were 5666 microg l(-1) for chlorpyrifos, 24,397 microg (l-1) for diuron, 4412 microg l(-1) for lindane, 5145 microg I(-1) for SDS, and 7.1 microg l(-1) for TBT. The median lethal concentrations (LC50) for M. squinado larval survival were 0.84 microg l(-1) (24 h) and 0.79 microg l(-1) (48 h) for chlorpyrifos, 2.23 microg(l(-1) (24 h) and 2.18 microg l(-1) (48 h) for lindane, and 687 microg l(-1) (48 h) for SDS. For P. serratus the LC50 values obtained were 0.35 microg l(-1) (24 h) and 0.22 microg l(-1) (48 h) for chlorpyrifos, 3011 microg l(-1) (24 h) and 3044 microg l(-1) (48 h) for diuron, 5.20 microg l(-1) (24 h) and 5.59 microg l(-1) (48 h) for lindane, and 22.30 microg l(-1) (24 h) and 17.52 microg l(-1) (48 h) for TBT. Decapod larvae, as expected, were markedly more sensitive to the insecticides than sea urchins and ascidians, and SDS was the least toxic compound tested for these organisms. Lowest observed effect concentrations (LOEC) of TBT for sea urchin and ascidian embryos, chlorpyrifos and lindane for crustacean larvae, and SDS, were similar to those found in many coastal areas indicating that there would be a risk to invertebrate embryos and larvae from exposure in the field to these pollutants.

Animals↗
PubMed2006

Relationship between micro-invertebrates and macrophytes in a wetland: Laguna Iberá (Corrientes, Argentina). Implications for water quality monitoring.

From November 2000 to September 2001, eight points in the Iberá lagoon were sampled bimonthly. At each point, pH, temperature and dissolved oxygen were measured and invertebrates were collected from the water around macrophytes by mean of a net of 180 mu m pore size. Four biotic indices were calculated and compared, given similar trends. The total number of taxa shows to be a good and simple indicator of water quality. Averaging indices across points we obtained a good positive correlation between indices and temperature. In this ecosystem, multi-habitat sampling must be used in order to obtain a good estimation of ecological integrity. The total number of taxa can be used for water quality assessment.

Animals↗
PubMed2005

Chemical defense in harvestmen (arachnida, opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators?

Two alkylated 1,4-benzoquinones were identified from the defensive secretion produced by the neotropical harvestman Goniosoma longipes (Gonyleptidae). They were characterized as 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. We tested the effectiveness of these benzoquinone secretions against several predator types, including invertebrates and vertebrates. Different predators were exposed to the harvestmen's gland secretion or to distilled water in laboratory bioassays. Our results indicate that secretions containing the 1,4-benzoquinones released by G. longipes can be an effective defense against predation, and that the effectiveness of the secretion is dependent on the predator type. The scent gland secretion repelled seven ant species, two species of large wandering spiders, and one frog species, but was not an effective defense against an opossum. Our study also demonstrates that the scent gland secretion of G. longipes can work as a chemical shield preventing the approach of three large predatory ants for at least 10 min. The chemical shield may protect the harvestman against successive attacks of the same ant worker and also allow the harvestman to flee before massive ant recruitment. Our data support the suggestion that chemical defenses may increase survival with some but not all potential predators. This variation in defense effectiveness may result from many interacting factors, including the attack strategy, size, learning ability, and physiology of the predators, as well as the chemical nature of the defensive compounds, type of emission, and amount of effluent released by the prey.

Adaptation, Physiological↗
PubMed1991

Cloning of a cDNA that encodes an invertebrate glutamate receptor subunit.

A full-length cDNA which encodes a putative glutamate receptor polypeptide was isolated from the pond snail Lymnaea stagnalis, using a short stretch of exonic sequence and two variants of the polymerase chain reaction. In this first comparison of invertebrate and vertebrate glutamate receptor sequences, the mature molluscan polypeptide, which comprises 898 amino acids and has a predicted Mr of 100,913, displays between 37% and 46% amino-acid identity to the rat ionotropic glutamate receptor subunits, GluR1 to GluR6.

Amino Acid Sequence↗