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PubMed1995

Nitric oxide synthase in invertebrates.

The gas nitric oxide is now recognized as an important signalling molecule that is synthesized from L-arginine by the enzyme nitric oxide synthase. This enzyme can be localized by different methods, including immunocytochemistry and the histochemical reaction for NADPH diaphorase. It has been demonstrated in various vertebrate cells and tissues, and recently several studies dealing with the production of nitric oxide in invertebrates have been published. Diploblastic animals, flatworms and nematodes seem to lack NADPH diaphorase activity but it has been found in the rest of the phyla studied. The most frequently reported sites for the production of nitric oxide are the central and peripheral nervous systems and, in primitive molluscs, the muscle cells. In insects, it has also been described in the Malpighian tubules. The roles of nitric oxide in invertebrates are closely related to the physiological actions described in vertebrates, namely, neurotransmission, defence, and salt and water balance. The recent cloning of the first nitric oxide synthase from an invertebrate source could open interesting avenues for further studies.

Animals↗

PubMed1990

Structure of an invertebrate gene encoding cytoplasmic intermediate filament (IF) proteins: implications for the origin and the diversification of IF proteins.

The structure of the single gene encoding the cytoplasmic intermediate filament (IF) proteins in non-neuronal cells of the gastropod Helix aspersa is described. Genomic and cDNA sequences show that the gene is composed of 10 introns and 11 exons, spanning greater than 60 kb of DNA. Alternative RNA processing accounts for two mRNA families which encode two IF proteins differing only in their C-terminal sequence. The intron/exon organization of the Helix rod domain is identical to that of the vertebrate type III IF genes in spite of low overall protein sequence homology and the presence of an additional 42 residues in coil 1b of the invertebrate sequence. Intron position homology extends to the entire coding sequence comprising both the rod and tail domains when the invertebrate IF gene is compared with the nuclear lamin LIII gene of Xenopus laevis presented in the accompanying report of Döring and Stick. In contrast the intron patterns of the tail domains of the invertebrate IF and the lamin genes differ from those of the vertebrate type III genes. The combined data are in line with an evolutionary descent of cytoplasmic IF proteins from a nuclear lamin-like progenitor and suggest a mechanism for this derivation. The unique position of intron 7 in the Helix IF gene indicates that the archetype IF gene arose by the elimination of the nuclear localization sequence due to the recruitment of a novel splice site. The presumptive structural organization of the archetype IF gene allows predictions with respect to the later diversification of metazoan IF genes. Whereas models proposing a direct derivation of neurofilament genes seem unlikely, the earlier speculation of an mRNA transposition mechanism is compatible with current results.

Amino Acid Sequence↗

PubMed1989

Extracellular matrix of sea urchin and other marine invertebrate embryos.

The extracellular matrix surrounding the sea urchin embryo (outer ECM) contains fibers and granules of various sizes which are organized in recognizable patterns as shown by ultrastructural studies, particularly stereoimaging techniques. The use of the ruthenium red method for retaining and staining the ECM, with modifications of the Luft (Anatomical Record 171:347-368, 1971) method for invertebrate embryos, allows for the clarification of certain structures, particularly fiber compaction in the interzonal region, and microvillus-associated bodies. The inner ECM in the sea urchin embryo includes the basal lamina and blastocoel matrix. Stereoimages show that the fibers which are loosely distributed in the blastocoel matrix become compacted around the periphery of the blastocoel to form the basal lamina. The ruthenium red method was also used on a number of marine invertebrate embryos and larvae, representing different phyla, to facilitate comparisons between their surface coats. The similarities observed in the specimens shown suggest that ECMs are widely found on marine invertebrate eggs, embryos, and larvae, and that they resemble vertebrate ECMs and may, therefore, have similar functions.

Animals↗

PubMed2006

Toxicity of nitrite to three species of freshwater invertebrates.

Nitrite is a compound with a high toxicity to aquatic animals. Several anthropogenic pollution sources are increasing the concentrations of this component of the nitrogen cycle. Despite this toxicity, there is little available literature on its effects on freshwater invertebrates. Laboratory bioassays were performed to obtain data on the lethal effects of nitrite to three species of freshwater invertebrates: the planarian Polycelis felina and the amphipods Echinogammarus echinosetosus and Eulimnogammarus toletanus. The LC(50), LC(10), and LC(0.01) values (mg/L NO(2)--N) at 24, 48, 72, and 96 h were calculated for each species. E. toletanus and E. echinosetosus were the most sensitive species, with 96 h LC(50) values of 2.09 and 2.59 mg/L NO(2)--N, respectively. In contrast, the planarian P. felina showed a higher tolerance to nitrite, with a 96 h LC(50) value of 60.0 mg/L NO(2)--N. The obtained results were compared with the reported nitrite data for other freshwater invertebrates. This study may contribute to a more appropriate assessment of the ecological risk of this compound in freshwater ecosystems.

Amphipoda↗

PubMed1992

Dispositions of junctional feet in muscles of invertebrates.

The structure and disposition of the feet occupying the junctions between sarcoplasmic reticulum (SR) and surface membrane/transverse tubules were studied in muscles from a variety of invertebrates. Feet were imaged by rotary shadowing of isolated junctional SR vesicles and by filtering of micrographs from grazing views of the junction in thin sections. The overall size and shape of invertebrate feet is the same as that of feet in skeletal and cardiac muscle of vertebrates. However, the arrangement of feet in invertebrate muscles differs from that in vertebrates. These findings are discussed in terms of known variations in properties of excitation-contraction coupling of the two phyla.

Animals↗

PubMed2002

C6-like and C3-like molecules from the cephalochordate, amphioxus, suggest a cytolytic complement system in invertebrates.

The mammalian immune system has cytotoxic mechanisms, both cellular and humoral, that destroy the membrane integrity of target cells. The main effector molecules of these cytolytic mechanisms-perforin, used by killer lymphocytes, and the membrane attack complex (MAC) components of the complement system-share a unique module called the MAC/perforin module. Until now, both immunological cytotoxicity and the MAC/perforin module have been reported only in jawed vertebrates. Here, we report the identification of a protein containing the MAC/perforin module from the invertebrate cephalochordate, amphioxus ( Branchiostoma belcheri), using expressed sequence tag (EST) analysis of the notochord. The deduced amino acid sequence of this molecule is most similar to the primary structure of human complement component C6 and is designated AmphiC6. AmphiC6 shares a unique modular structure, including the MAC/perforin module, with human C6 and other MAC components. Another EST clone predicts the presence of a thioester-containing protein with the closest structural similarity to vertebrate C3 (therefore designated AmphiC3). AmphiC3 retains most of the functionally important residues of vertebrate C3 and is shown by phylogenetic analysis to be derived directly from the common ancestor of vertebrate C3, C4, and C5. Only opsonic activity has been assigned to the invertebrate complement system until now. Therefore, this is the first molecular evidence for complement-mediated immunological cytotoxicity in invertebrates.

Amino Acid Sequence↗

PubMed1999

Development and application of a high-performance liquid chromatography screening method for aromatic compounds in invertebrate tissues

Contamination of marine invertebrates by aromatic compounds (ACs) can occur from a variety of environmental sources, both natural and anthropogenic. Invertebrate species bioaccumulate ACs because they metabolize and eliminate them at a much slower rate than do vertebrates, such as fish. We have developed a high-performance liquid chromatography (HPLC) UV fluorescence screening method that measures ACs in invertebrate tissues. Screening methods have proven to be useful in response to environmental emergencies (e.g., oil spills) and in environmental monitoring because they are more rapid and less expensive than detailed analyses. This method was validated using three species of bivalves and lobster hepatopancreas and tail muscle as test samples. The AC screening method at naphthalene, phenanthrene, and benzo[a]pyrene wavelength pairs showed good correlation to GC/MS results. The method was also used successfully in response to the North Cape oil spill, off Narragansett, Rhode Island.http://link.springer-ny. com/link/service/journals/00244/bibs/37n2p220.html

Journal Article↗

PubMed2003

Damaging UV radiation and invertebrate predation: conflicting selective pressures for zooplankton vertical distribution in the water column of low DOC lakes.

In nature most organisms have to manage conflicting demands of food gathering, predator avoidance, and finding a favorable abiotic environment (oxygen, temperature, etc.) in order to maximize their fitness. In the vertical water column of lakes with high solar ultraviolet radiation (UV) and invertebrate predators, zooplankton face two particularly strong and conflicting selective pressures. During daylight hours invertebrate predators often induce an upward vertical migration of zooplankton prey while potentially damaging UV forces a downward migration. We used 2.2 m long columns suspended vertically in a lake to conduct 2x2 factorial experiments to examine patterns of depth selection behavior by zooplankton in the presence and absence of both the invertebrate predator Chaoborus and UV. We hypothesized that Chaoborus and UV both affect the distribution of zooplankton and a combination of both factors would lead to a narrowing of depth distribution. We found that when Chaoborus were present zooplankton tended to be distributed at shallower depths in the columns, while in the presence of UV they exhibited a deeper distribution. Chaoborus themselves were always found near the bottom of the columns regardless of the UV treatment. Simultaneous exposure to predators and UV resulted in a peak of zooplankton (especially Daphnia catawba) distribution at intermediate depths. In a significant number of cases, depth range was narrowed in response to Chaoborus, UV, or both.

Animals↗

PubMed1989

Adrenergic receptor homologies in vertebrate and invertebrate species examined by DNA hybridization.

The deduced protein sequences of the mammalian adrenergic receptors (ARs) suggest that these proteins have evolved by several ancient gene duplication events. To investigate in what species these events may have occurred DNA fragments encoding the family of adrenergic receptors from human (beta 1AR and alpha 2AR) and hamster (beta 2AR and alpha 1AR) were used to detect homologous sequences in other vertebrates, invertebrates and unicellular organisms by Southern blot hybridization analysis. Sequences homologous to hamster beta 2AR were detected in lower vertebrates, invertebrates and Dictyostelium, but not in yeast or bacteria. Within vertebrates, sequences strongly homologous to human beta 1AR and human platelet alpha 2AR were confined to the higher vertebrates only. In the invertebrates, only Drosophila contained sequences homologous to hamster alpha 1AR. Our results suggest that non-mammalian species may contain receptors homologous to the mammalian adrenergic receptors and that the sequences homologous to human beta 2AR have been the most strongly conserved.

Animals↗

PubMedDate not supplied

Immunocytochemical demonstration of vertebrate peptides in invertebrates: the homology concept.

During the last years many positive immunocytochemical reactions have been described in invertebrates using antisera to vertebrate regulatory peptides. However, due to the specificity problems associated with immunocytochemistry, the significance of the majority of these findings remains unclear, as so far only a few of the substances causing the immunoreactions in invertebrates have been isolated. It is proposed that comparing the localizations of "vertebrate" peptides in different and not closely related species of an invertebrate group may give a clue to the physiological relevance of the immunoreactive substances.

Animals↗

PubMed1991

Purification and biochemical characterization of an invertebrate interleukin 1.

Interleukin 1 (IL-1) is a major immunoregulatory protein released by macrophages with many host defense related properties. That IL-1 has been found in the invertebrates attests to its importance in homeostasis. The first step in comparing the vertebrate protein to its invertebrate correlate is to purify the protein to study. We have purified to homogeneity IL-1 isolated from the coelomic fluid of the starfish Asterias forbesi. The IL-1 had isoelectric points of 7.4, 5.4 and 4.8. The pI 4.8 species had a molecular weight of 22,000 and the pI 7.4 and 5.4 species both had Mr of 17,000. Higher Mr forms were also found. These molecules were biologically active in the human melanoma A375 cytotoxicity assay for IL-1, and were also able to stimulate murine dermal fibroblast proliferation, protein synthesis, and PGE2 production. The pI 4.8 and 5.4 forms were purified to homogeneity and the amino acid composition was determined. The pI 4.8 and 5.4 species were purified more than 200-fold to specific activities of 3 x 10(6) and 1 x 10(6) units mg-1, respectively. The pI 7.4 form was isolated and partial N-terminal sequence analysis was performed. The similarities of molecular weight, isoelectric points and biological properties between vertebrate and invertebrate IL-1 show that it is an important, evolutionarily stable host defense molecule.

Amino Acid Sequence↗

PubMed1993

HIV gp120 alteration of DAMA and IL-1 alpha induced chemotaxic responses in human and invertebrate immunocytes.

The effects of a synthetic peptide fragment of human immunodeficiency virus gp120 (HIV gp120) on opioid (D-ala2-D-met5 enkephalinamide; DAMA) and interleukin-1 (IL-1) induced chemotactic responses in human granulocytes and monocytes and invertebrate (Mytilus edulis) immunocytes were studied. Both DAMA and IL-1 increased the velocity of cell migration from both species and the response is chemotactic (e.g. directed). Non-treated control cells move randomly or not at all. The addition of gp120 to DAMA or IL-1 treated human granulocytes or monocytes results in a slower movement which is chemokinetic (loss of directionality or random) in nature. A similar phenomenon occurs in the invertebrate immunocytes. If gp120 alone is added, it inhibits the movement of spontaneously active human granulocytes and Mytilus edulis immunocytes. In contrast, it stimulates chemokinesis of spontaneously active human monocytes. These responses occur immediately after addition of the peptide. Based on experiments with the selective calcium channel antagonist nimodipine, it appears that the gp120 causes its effects by irreversible binding to a calcium channel. Our results suggest a universal inhibitory mechanism is occurring since the invertebrate immunocytes must recognize HIV gp120 peptide to result in this effect, possibly through a CD4 or other type of surface determinant.

Animals↗

PubMed1992

Invertebrate GABA and glutamate receptors: molecular biology reveals predictable structures but some unusual pharmacologies.

Determination of the sequences of invertebrate gamma-aminobutyric acid (GABA)-gated and glutamate-gated receptor/ion channels, through the application of recombinant DNA methods, is not just an academic exercise to effect evolutionary comparisons with the sequences of the corresponding vertebrate receptors. The isolation of DNA clones would provide the tools to investigate the exact locations and functional properties of these neurotransmitter receptors within simple nervous systems. In addition, since GABA receptors, at least, have been suggested to be the targets of certain pesticides, the availability of invertebrate receptor cDNAs might provide the agrochemical industry with the basis for 'high-throughput' screening methods for novel pesticidal compounds. Recently, the isolation of molluscan and Drosophila GABA receptor and glutamate receptor cDNAs, and the pharmacological properties of a GABA receptor expressed from one of these clones, have been reported. These studies should stimulate further research into the electrophysiology and pharmacology of native invertebrate ion channel proteins.

Animals↗

PubMed1989

The effects of road and bridge construction on the bank-root macrobenthic invertebrates of a Southern Nigerian stream.

A comparative study was conducted at three stations on a fourth order Nigerian stream to evaluate the effects of a road and bridge construction on the macrobenthic invertebrates of the bank-root biotope. Siltation and sedimentation appear to be the important factors affecting macroinvertebrates. At station 2, the construction site, there was a considerable reduction in the occurrence and abundance of invertebrate taxa; different groups of invertebrates showed varying responses to perturbational stress; the taxa richness, general diversity and evenness were also low. Irregular fluctuations in diversity and evenness suggested that the benthic community of station 2 was less stable than those of upstream and downstream stations. The concentrated dominance of Ephemeroptera and Coleoptera at station 2, despite low diversity, reflected the ability of a few tolerant taxa to occur there in high abundance. Faunal comparisons of the three stations confirmed the perturbational stress caused by construction activities.

Journal Article↗

PubMed1984

The characterization of invertebrate troponin C.

TNCs from lobster, mussel, and squid migrated with rabbit TNC at an apparent mol. wt of 18,000. Electrophoretic mobilities in the presence or absence of Ca2+ were compared: the electrophoretic mobility of rabbit TNC was greater in the presence of Ca2+ than it its absence, but all invertebrate TNCs tested migrated identically, whether Ca2+ was present or not. The Ca2+-binding capacity of invertebrate TNCs was only one Ca2+ ion per molecule. The alpha-helix contents in the presence or absence of Ca2+ were compared: rabbit TNC changed by a value of 16% and invertebrate TNCs by 4%. Antibodies to loligo TNC did not cross-react with rabbit TNC, but did interact with their molluscan TNCs.

Animals↗

PubMed1986

Presence of O6-methylguanine acceptor protein in the tissues of different classes of vertebrates and invertebrates.

We have measured the ability of extracts of tissues from several species of mammals, birds, reptiles, amphibia and fish to demethylate adducts of O6-methylguanine in exogenous DNA by transfer of the methyl group to an acceptor protein. Our study also encompassed tissues from a smaller number of invertebrates, from arthropods, molluscs and annelids. The vertebrate tissues used were liver, brain, spleen and kidney. In the case of the invertebrates we sampled liver, neural tissue, gonads, digestive tract and hepatopancreas. There was no consistent change in the amount of acceptor activity per unit of protein or DNA going from cold-blooded to warm-blooded vertebrates. Liver invariably had the highest amount; this finding was not unexpected since metabolic processes in the liver are high, and good cellular protective mechanism important. Inter-class comparisons within the vertebrates are highly speculative, and hindered by the fact that there is little information on carcinogenesis in animals other than rodents and humans. O6-methylguanine acceptor activity was found in all the invertebrate tissues tested. The amounts were variable, 0.003-0.0051 fmol/micrograms cellular DNA, but the values fell within the range of those found in the tissues of vertebrates.

Amphibians↗

PubMed1994

The effect of troponin C substitution on the Ca(2+)-sensitive ATPase activity of vertebrate and invertebrate myofibrils by troponin Cs with various numbers of Ca(2+)-binding sites.

The effect of four different classes of troponin C with different numbers of Ca(2+)-binding sites was investigated on the Ca(2+)-activation profiles of the ATPase of troponin C-depleted myofibrils prepared from vertebrate fast skeletal (rabbit), vertebrate cardiac (bovine) and invertebrate crustacean tail striated (crayfish, lobster) muscles. Troponin C from vertebrate sources [fast skeletal (rabbit, chicken) with four Ca(2+)-binding sites, and cardiac (bovine, chicken) with three Ca(2+)-binding sites] activated the Ca(2+)-ATPase of troponin C-depleted myofibrils from the vertebrate skeletal or cardiac muscles, but did not activate the invertebrate troponin C-depleted crustacean myofibrils. On the other hand, two kinds of crustacean (crayfish, lobster) troponin C with two Ca(2+)-binding sites activated only crustacean troponin C-depleted myofibrils. One invertebrate molluscan (Akazara scallop) troponin C with one Ca(2+)-binding site did not activate the Ca(2+)-ATPase of the troponin C-depleted myofibrils from either vertebrate or crustacean striated muscles. The results obtained from the four kinds of combinations of troponin C and troponin C-depleted myofibrils from vertebrate skeletal and cardiac muscles demonstrated that the characteristic cooperativity of the Ca(2+)-activation profiles of both vertebrate skeletal and cardiac myofibrils was determined by the skeletal or cardiac origin of troponin C molecules, irrespective of the animal species, and the Ca(2+)-affinity of the myofibrillar ATPase was related to the skeletal or cardiac origin of both the troponin C and myofibrils. These findings indicated that each of the four classes of troponin C has its own characteristic Ca(2+)-activation profile for each kind of myofibril examined in the present study.

Animals↗

PubMed1995

NO-synthase: what can research on invertebrates add to what is already known?

The present study attempts to review presently known data regarding the distribution of nitric oxide (NO) synthase and the function of NO in invertebrate species. NO is synthesized from L-arginine by the enzyme NO-synthase, and activates guanylate cyclase which in turn leads to an increase in levels of cGMP in target cells. Major contributions to the knowledge of NO as a messenger molecule in invertebrates have been made by NADPH-diaphorase histochemistry and biochemical assays. These techniques suggest the presence of a L-arginine/NO pathway in a variety of tissues, thus implicating multiple roles for NO in invertebrates.

Animals↗