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Agglutinins in body fluids from several invertebrate and vertebrate (fish) species demonstrated a rare specificity in reacting differently with erythrocytes from human females and males. The body fluids from these animals may provide readily available reagents to study the little known sex-specific components on cell surfaces.
The authors give an annotated list of venomous Invertebrates occurring off Tunisian seas. They point out the action of their venom, the injuries about man, and different therapeutic and prophylactic methods. They conclude that the Cnidaria are the most abundant and most dangerous.
We describe "universal" DNA primers for polymerase chain reaction (PCR) amplification of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 11 invertebrate phyla: Echinodermata, Mollusca, Annelida, Pogonophora, Arthropoda, Nemertinea, Echiura, Sipuncula, Platyhelminthes, Tardigrada, and Coelenterata, as well as the putative phylum Vestimentifera. Preliminary comparisons revealed that these COI primers generate informative sequences for phylogenetic analyses at the species and higher taxonomic levels.
Infectious disease is the single most devastating problem in mollusc and shrimp aquaculture. Pathogens causing the greatest problems have been identified as viruses, prokaryotes, and protozoans. Two approaches employing methods of biotechnology have been proposed to prevent, manage, and control mollusc and shrimp diseases. The first is development of a diagnostic scheme for detection and identification of pathogens, using molecular probes. This offers the opportunity for prophylactic measures to be taken. Molecular probes have been prepared for the major pathogens of molluscs, but in the case of shrimp pathogens, only a few are available. Monoclonal antibodies have also been prepared and are used in immunodiagnosis, e.g., immunofluorescence detection. Such diagnostic tools are relatively new to aquaculture, but have enormous potential. A second approach to the control of disease in marine invertebrates, notably shrimp, involves use of genetically transformed strains resistant to specific pathogens. Pathogen-resistant transgenic animals have been developed, but such research has only just begun for molluscs and shrimp. Transfection methods applied to mollusc and shrimp embryos have been successful, with preliminary data showing efficiency of heterologous promoters in controlling expression of reporter genes. Other transformation systems also show promise, including transposable elements and densoviruses.
Glial cells in invertebrates have been known for a long time, however, a systematic analysis of the development and the role of these cells has been missing. In the last few years, the development of new markers and the identification of genes specifically expressed in glial cells have shed some light on the mechanisms leading to gliogenesis in Drosophila melanogaster. The organisation of glial cells in the central and in the peripheral nervous system has been described and the origin of some of these cells has also been assessed. Lineage studies have shown that glial cells display different mechanisms of differentiation depending on their position in the nervous system. In some cases, glial differentiation seems intimately associated with neurogenesis, as has already been shown in the vertebrate peripheral nervous system. This suggests that similar developmental mechanisms have been conserved during evolution and that Drosophila can be used as a model system to study glial differentiation in vertebrates.
In most deuterostome eggs, a transient increase in the intracellular free calcium concentration (Cai) occurs after fertilization and is essential for egg activation. How one spermatozoo triggers this calcium signal remains an enigma. In the light of our own results, we suggest a model, leading to the calcium signal and common to invertebrate and mammalian systems, where phosphorylation on tyrosine and phospholipase C gamma (PLC gamma) are interconnected pathways stimulated by a multimolecular complex involving integrins.
Invertebrate visual transduction involves a second messenger cascade process that leads to an increase in membrane conductance. The identity of the second messenger that gates the light-dependent channels is presently a major focus of attention. Cyclic GMP, inositol trisphosphate and Ca2+ are the most likely candidates for being such a messenger in the species studied so far. Here we review the available evidence for each of these molecules.
The beta-thymosins are distributed throughout the vertebrate phyla, and all known vertebrate beta-thymosins bind actin monomers. To determine whether beta-thymosin-like peptides function as actin-binding proteins in invertebrates, we fractionated perchloric acid extracts of the gonads of both the sea urchin, Arbacia punctulata, and the scallop, Argopecten irradians, and screened the fractions for proteins which could be crosslinked to actin. In each case a peptide was isolated which crosslinks to actin from both rabbit skeletal muscle and scallop cross-striated adductor muscle; both peptides were sequenced and each was found to consist of 40 amino acid residues, compared with 41-43 residues for the vertebrate beta-thymosins. The sequences of the scallop and sea urchin beta-thymosins are 80% identical to each other, 75% identical to residues 1-40 of thymosin beta4, and 72-80% identical to residues 1-40 of other vertebrate beta-thymosins. The sea urchin peptide was found to inhibit actin polymerization and nucleotide exchange. The affinity of the sea urchin peptide for rabbit muscle actin is apparently lower than that of thymosin beta4, since about twice the concentration of sea urchin peptide is required to give inhibition of actin polymerization or nucleotide exchange equivalent to thymosin beta4.
6-dimethylaminopurine (6-DMAP), a potent protein kinase inhibitor, drives most cells into an interphasic stage. Experiments were undertaken with oocytes from three marine invertebrate species, i.e., Mytilus edulis, Spisula solidissima, and Strongylocentrotus droebachiensis, wherein oocytes were arrested at different phases of meiosis. 6-DMAP induced a continuous DNA synthesis in meiotic cells, whereas it allowed a single round of DNA replication in treated mitotic cells, regardless of species considered. The effects of 6-DMAP were accompanied in all cases by rephosphorylation on tyrosine of the p34cdc2 homolog, the M-phase promoting factor (MPF) catalytic subunit. The fact that 6-DMAP overcomes the inhibitory control of replication during meiosis suggests that this process depends upon protein phosphorylation, while DNA synthesis regulation in mitotic cells relies on 6-DMAP-insensitive events.
Peptidylglycine alpha-hydroxylating monooxygenase (PHM), an enzyme involved in formation of neuropeptides with a C-terminal amide functionality in mammals and amphibians, was isolated from the head of an invertebrate, the honeybee, Apis mellifera, and purified 220-fold in 1% overall yield. The bee PHM has a molecular weight of 71,000, is membrane associated but can be solubilized with a detergent (n-octyl-beta-D-glucopyranoside), and cross-reacts with rabbit antibodies generated toward bacterially expressed rat PHM. In the presence of copper, oxygen, and ascorbic acid, the enzyme hydroxylates model tripeptides such as dansyl-L-Phe-L-Phe-Gly on the methylene carbon of the glycine residue with retention of configuration. Using this tripeptide as substrate, the Km is 1.7 microM and the Vmax is 2.3 nmol.micrograms-1.h-1. Treatment of the insect PHM with D-Phe-L-Phe-D-vinylglycine, a substrate analogue and mechanism-based inactivator of PHM from pig pituitary, results in irreversible loss of activity. The diastereomeric analogue, D-Phe-L-Phe-L-vinylglycine, is only a competitive inhibitor (IC50 = 320 microM).
Ageing is a complex phenomenon which remains a major challenge to modern biology. Although the evolutionary biology of ageing is well understood, the mechanisms that limit lifespan are unknown. The isolation and analysis of single-gene mutations which extend lifespan (Age mutations) is likely to reveal processes which influence ageing. Caenorhabditis elegans is the only metazoan in which Age mutations have been identified. The Age mutations not only prolong life, but also confer a complex array of other phenotypes. Some of these phenotypes provide clues to the evolutionary origins of these genes while others allude to mechanisms of lifespan-extension. Many of the Age genes interact and share a second common phenotype, that of stress resistance. Rather than invertebrate ageing being determined by a 'clock mechanism', a picture is emerging of ageing as a non-adaptive process determined, in part, by resistance to intrinsic stress mediated by stress-response genes.
Bow-shaped particle arrays on the P-faces of the photoreceptor terminals R1-R6 in the lamina ganglionaris of the house fly represent the presynaptic sites of chemically mediated multiple-contact synapses (Shaw and Stowe, '82, Saint Marie and Carlson, '82). A particle array consists of two polar patches of regularly arranged particles and a central patch of irregularly arranged ones. Corresponding to these P-face arrays, the receptor E-faces have lattices of pits opposite the polar patches, and pits and some particles at the center. The presynaptic particle array corresponds in its dimensions to the electron-dense bar found in thin sections. The center-to-center spacing of the regularly arranged particles agrees with the spacing of striations found in the bar overlying the two polar elements of the postsynaptic tetrad. The elements in the two medial postsynaptic positions are hyperpolarizing monopolar cells L1 and L2, which show a strip of P-face particles within an otherwise bare postsynaptic membrane enclosed by a ridge, and a bare E-face. Comparison with other invertebrate synapses reveals two types of organization of postsynaptic membranes. IMPs fracture with the postsynaptic P-face in GABAergic and/or inhibitory synapses and with the E-face in glutaminergic and/or excitatory synapses; the fly photoreceptor synapse thus fits in the former category.
The endostyle of invertebrate chordates is a pharyngeal organ that is thought to be homologous with the follicular thyroid of vertebrates. Although thyroid-like features such as iodine-concentrating and peroxidase activities are located in the dorsolateral part of both ascidian and amphioxus endostyles, the structural organization and numbers of functional units are different. To estimate phylogenetic relationships of each functional zone with special reference to the evolution of the thyroid, we have investigated, in ascidian and amphioxus, the expression patterns of thyroid-related transcription factors such as TTF-2/FoxE4 and Pax2/5/8, as well as the forkhead transcription factors FoxQ1 and FoxA. Comparative gene expression analyses depicted an overall similarity between ascidians and amphioxus endostyles, while differences in expression patterns of these genes might be specifically related to the addition or elimination of a pair of glandular zones. Expressions of Ci-FoxE and BbFoxE4 suggest that the ancestral FoxE class might have been recruited for the formation of thyroid-like region in a possible common ancestor of chordates. Furthermore, coexpression of FoxE4, Pax2/5/8, and TPO in the dorsolateral part of both ascidian and amphioxus endostyles suggests that genetic basis of the thyroid function was already in place before the vertebrate lineage.
This study examined the temporal component of pentachlorobenzene lethal body residues among three freshwater invertebrates. Also, using previous fluoranthene data allowed a more detailed examination of the role of biotransformation in lethal body residues and comparisons of lethal residues across chemical classes. Time-dependent toxicity of fluoranthene and pentachlorobenzene were compared among Hyalella azteca, Chironomus tentans, and Diporeia spp. Lethal body residues required for 50% mortality (LR50) were not constant and decreased with exposure time for all species. Fluoranthene was most toxic to C. tentans with LR50 values of 0.38 micromol x g(-1) at 2 d to 0.15 micromol x g(-1) at 10 d and least toxic to Diporeia spp. with values of 9.97 micromol x g(-1) at 10 d to 3.67 micromol x g(-1) at 28 d. The LR50 values for H. azteca were intermediate and ranged from 2.25 micromol x g(-1) at 5 d to 0.56 micromol x g(-1) at 28 d. Pentachlorobenzene LR50 values were less variable among species and ranged from 1.20 micromol x g(-1) at 4 d to 0.81 micromol x g(-1) at 10 d for C. tentans, 5.0 micromol x g(-1) at 20 d and 2.75 micromol x g(-1) at 28 d for Diporeia spp., and 1.51 micromol x g(-1) at 4 d and 0.71 micromol x g(-1) at 28 d for H. azteca. When LR50 values for fluoranthene and pentachlorobenzene were compared at steady state, the lethal residues for the amphipod species were within the range expected for nonpolar narcotic chemicals (anesthetics); however, C. tentans was more sensitive to fluoranthene than pentachlorobenzene, confirming our previous hypothesis that biotransformation of fluoranthene likely produces a metabolite(s) acting by some specific mechanism of action. The information collected from this study allows a greater understanding of residue-response relationships, specifically relative species sensitivities.
Sperm are attracted by chemical substances which are released by the egg. This process is called chemotaxis. Several molecules that are involved in chemotactic signaling of sperm from marine invertebrates are described and a model of the signaling pathway is presented. We discuss the motor response during chemotaxis and propose a model of the navigation strategy of sperm.
Immunoglobulin E (IgE)-mediated food allergy to crustaceans and mollusks is relatively common and affected individuals typically react to a range of different species. The only known major allergen of shrimp was first described over 20 years ago and later identified as the muscle protein tropomyosin. This protein may be useful as a defined and relevant diagnostic marker for allergic sensitization to invertebrate foods. In order to generate an assay reagent suitable for this purpose, tropomyosin from the shrimp Penaeus aztecus (Pen a 1) was produced as a recombinant protein in Escherichia coli and characterized with respect to IgE antibody binding properties in comparison to natural shrimp tropomyosin. Hexahistidine-tagged rPen a 1 accumulated as a predominantly soluble protein in the E. coli expression host and a two-step chromatographic procedure provided a high yield of pure and homogeneous protein. rPen a 1 displayed chromatographic and folding characteristics similar to those of purified natural shrimp tropomyosin. Serum preincubation with serial protein dilutions revealed similar capacity of recombinant and natural tropomyosin to compete with immobilized shrimp extract for IgE binding. rPen a 1 was further shown to extensively and specifically compete for IgE binding to extracts of other crustacean species, house dust mite and German cockroach.
This article describes a novel application of contrast-enhanced MR microscopy to trace nerve cells and pathways through small invertebrate brains. Using the cuttlefish Sepia officinalis (Cephalopoda) as a model, the cells and pathways of one of the brain nerves were labeled with paramagnetic cobalt(II) ions by conventional centripetal cobalt iontophoresis. In MR microscopy, the cobalt-labeled cell bodies and pathways became hypointense in 9.4 T spin echo images. Their course and distribution were identical with those seen with conventional histological techniques after cobalt sulphide precipitation (with or without subsequent silver intensification). Magn Reson Med 45:575-579, 2001.
We have isolated a cDNA clone from the honeybee brain encoding a dopamine receptor, AmDop2, which is positively coupled to adenylyl cyclase. The transmembrane domains of this receptor are 88% identical to the orthologous Drosophila D2 dopamine receptor, DmDop2, though phylogenetic analysis and sequence homology both indicate that invertebrate and vertebrate D2 receptors are quite distinct. In situ hybridization to mRNA in whole-mount preparations of honeybee brains reveals gene expression in the mushroom bodies, a primary site of associative learning. Furthermore, two anatomically distinct cell types in the mushroom bodies exhibit differential regulation of AmDop2 expression. In all nonreproductive females (worker caste) and reproductive males (drones) the receptor gene is strongly and constitutively expressed in all mushroom body interneurons with small cell bodies. In contrast, the large cell-bodied interneurons exhibit dramatic plasticity of AmDop2 gene expression. In newly emerged worker bees (cell-cleaning specialists) and newly emerged drones, no AmDop2 transcript is observed in the large interneurons whereas this transcript is abundant in these cells in the oldest worker bees (resource foragers) and older drones. Differentiation of the mushroom body interneurons into two distinct classes (i.e., plastic or nonplastic with respect to AmDop2 gene expression) indicates that this receptor contributes to the differential regulation of distinct neural circuits. Moreover, the plasticity of expression observed in the large cells implicates this receptor in the behavioral maturation of the bee.