SEARCH · PubMed Health

Results for “Invertebrates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

PubMed2001

Gene transfer and plasmid instability within pilot-scale sewage filter beds and the invertebrates that live in them.

The environmental plasmid pQKH6 was transferred conjugatively between strains of Pseudomonas putida at mean frequencies of up to 8.4x10(-4) within pilot-scale sewage filter beds. This frequency was 10-fold higher than that reported previously for this environment and was probably due to seasonal temperature changes. Many (45%) of the plasmids isolated subsequently from the filter beds had restriction fragment length polymorphism (RFLP) profiles that differed from that expected for pQKH6. RFLP analysis revealed structural rearrangements occurring within a particularly restriction-site-rich region of the plasmid. Although no evidence was obtained showing the indigenous invertebrate populations within the filter beds to influence the rate of gene transfer, pQKH6 was transferred with frequencies of up to 1.6x10(-2) within the guts of the filter-bed-dwelling Sylvicola fenestralis larvae during laboratory experiments. This transfer was strongly influenced by donor to recipient ratios. Laboratory experiments also showed that Serratia fonticola survived better within invertebrate guts than P. putida. This evidence, along with experiments showing that S. fonticola could participate in pQKH6 transfer within filter-bed biofilm, identify this bacterium as a better model than P. putida for examining the effect of invertebrates on gene transfer.

Journal Article↗

PubMed1983

Freezing resistance in intertidal invertebrates.

Intertidal invertebrates survive exposures to temperatures as low as -20 degrees C by tolerating the presence of tissue ice. This resistance to freezing is influenced by such factors as the time and temperature of exposure, the rate of cooling during tissue ice formation, the temperature and salinity of the seawater to which the animals have adapted, and the oxygen content of tissues. Freezing injury appears to result primarily from extracellular ice formation, although for certain smaller invertebrates that cool at rates exceeding 0.4 degrees C min-1 during tissue ice formation, intracellular ice formation may be the cause of freezing injury. Extracellular ice formation is a dehydration stress, and injury resulting from extracellular ice appears to involve membrane damage resulting from the loss of a critical amount of cellular water. Physiological mechanisms that lower the temperatures at which extracellular ice causes injury are dependent on factors that either (a) "bind" a certain fraction of intracellular water and thus reduce the amount of water lost during freezing, or (b) increase the resistance of cells to greater quantities of tissue ice. Certain structural components and glycoproteins have been isolated from an intertidal mollusk that can impede or prevent the formation of ice. However, a quantitative relationship between these components and freezing resistance has not been established. The resistance to greater quantities of tissue ice appears to be associated with low levels of tissue oxygen and with anaerobic metabolism. A rise in blood calcium concentration following a shift from aerobic to anaerobic metabolism can account for part of the increased resistance of an intertidal mollusk to greater quantities of tissue ice, while membrane changes and factors that reduce the toxic effects of oxygen may also be involved. The possibility that oxygen is associated with injury resulting from extracellular ice formation in intertidal invertebrates deserves further investigation.

Adaptation, Physiological↗

PubMed2004

Invertebrates yield a plethora of atypical guanylyl cyclases.

Invertebrate model systems have a long history of generating new insights into neuronal signaling systems. This review focuses on cyclic GMP signaling and describes recent advances in understanding the properties and functions of guanylyl cyclases in invertebrates. The sequencing of three invertebrate genomes has provided a complete catalog of the guanylyl cyclases in C. elegans, Drosophila, and the mosquito Anopheles gambiae. Using this data and that from cloned guanylyl cyclases in Manduca sexta, C. elegans, and Drosophila, plus predictions and models from vertebrate guanylyl cyclases, evidence is presented that there is a much broader array of properties for these enzymes than previously realized. In addition to the classic homodimeric receptor guanylyl cyclases, C. elegans has at least two receptor guanylyl cyclases that are predicted to require heterodimer formation for activity. Soluble guanylyl cyclases are generally recognized as being obligate heterodimers that are activated by nitric oxide (NO). Some of the soluble guanylyl cyclases in C. elegans may heterodimeric, but all appear to be insensitive to NO. The beta2 soluble guanylyl cyclase subunit in mammals and similar ones in Manduca and Drosophila are active in the absence of additional subunits and there is evidence that Drosophila and Anopheles also express an additional subunit that enhances this activity.

Amino Acid Sequence↗

PubMed2006

Offspring size effects mediate competitive interactions in a colonial marine invertebrate.

Over the past 30 years, numerous attempts to understand the relationship between offspring size and fitness have been made, and it has become clear that this critical relationship is strongly affected by environmental heterogeneity. For marine invertebrates, there has been a long-standing interest in the evolution of offspring size, but there have been very few empirical and theoretical examinations of post-metamorphic offspring size effects, and almost none have considered the effect of environmental heterogeneity on the offspring size/fitness relationship. We investigated the post-metamorphic effects of offspring size in the field for the colonial marine invertebrate Botrylloides violaceus. We also examined how the relationship between offspring size and performance was affected by three different types of intraspecific competition. We found strong and persistent effects of offspring size on survival and growth, but these effects depended on the level and type of intraspecific competition. Generally, competition strengthened the advantages of increasing maternal investment. Interestingly, we found that offspring size determined the outcome of competitive interaction: juveniles that had more maternal investment were more likely to encroach on another juvenile's territory. This suggests that mothers have the previously unrecognized potential to influence the outcome of competitive interactions in benthic marine invertebrates. We created a simple optimality model, which utilized the data generated from our field experiments, and found that increasing intraspecific competition resulted in an increase in predicted optimal size. Our results suggest that the relationship between offspring size and fitness is highly variable in the marine environment and strongly dependent on the density of conspecifics.

Animals↗

PubMed2004

Lymnaea EGF and gigantoxin I, novel invertebrate members of the epidermal growth factor family.

In this review, we compare the sequence and structural relationships of two epidermal growth factor (EGF) family related proteins that have recently been discovered in invertebrate species. The first is L-EGF, a secreted growth factor from the gastropod mollusk Lymnaea stagnalis. The second is a peptide toxin (Gigantoxin I), isolated from the sea anenome Stichodactyla giganteus, which can paralyze crabs. L-EGF and Gigantoxin I share striking sequence similarity with mammalian erbB1 receptor ligands, including most of the essential receptor binding sites. Intriguingly, L-EGF's tertiary structure resembles more the structure of the EGF-like domain of coagulation factors. That is, the secondary and tertiary structure of L-EGF indicates the presence of a double-stranded beta-sheet but also suggests that this protein, in contrast to all other erbB1 ligands, contains a calcium-binding domain. One of the most remarkable features of L-EGF and Gigantoxin I however, is the indication that these protein are synthesized as non-membrane bound secreted peptides. This feature sets L-EGF and Gigantoxin I apart from all other members of the EGF family or EGF-like proteins identified thus far. We discuss sequence similarities and dissimilarities in the light of indications that, despite the more than 600 million years of phylogenetic distance separating both these invertebrates from mammals, Gigantoxin I and L-EGF retain some affinity for the mammalian erbB-family of receptors. Considering that mammalian EGF and its family members are frequently implicated in neoplastic diseases, the increasing number of identified and characterized invertebrate EGF family members may provide valuable leads in the design of erbB receptor antagonists.

Animals↗

PubMed1993

Detection of a type IX collagen-related mRNA in an invertebrate, the marine annelid Nereis virens.

Fibrous and non-fibrous collagens have been described in both vertebrate and invertebrate animals. However, there has been limited characterization of non-fibrous collagens and their corresponding genes in invertebrate animals. In the present study we have used as a probe an avian cDNA clone which encompasses the COL3, NC3 and part of the COL2 domain of the collagen alpha 3(IX) subunit. This probe hybridized to mRNA obtained from the cuticle and body of the marine annelid, Nereis virens. Northern blot hybridization exhibited an mRNA of ca. 7.5-8 kilobases which in situ hybridization shows to be most abundant over cuticle-associated cells. Dot-blot hybridization, comparing cuticle mRNA and body mRNA, indicates that this collagen mRNA is five times more abundant in the cuticle. The composite data suggest evolutionary conservation, in both vertebrate and invertebrate animals, of a non-fibrillar collagen.

Animals↗

PubMed2005

An ancient role for a prokineticin domain in invertebrate hematopoiesis.

Hemopoietic development requires firm control of cell proliferation and differentiation. Although recent research has revealed conserved function of transcription factors and signaling pathways regulating lineage commitment in hemopoietic development in Drosophila melanogaster and vertebrates, little is known about hemopoietic cytokines among the invertebrate phyla. In the present study, we show that differentiation and growth of hemopoietic stem cells in vitro from an invertebrate, Pacifastacus leniusculus, require an endogenous cytokine-like factor, astakine, containing a prokineticin (PK) domain. Astakine induces a strong hematopoiesis response in live animals. An astakine homologue was also found in the shrimp, Penaeus monodon. So far, PK domains are only identified in vertebrates, in which they, for example, direct angiogenic growth. Our finding of the first PK-like cytokine characterized from any invertebrate provides novel information concerning the evolution of growth factors and blood cell development.

Amino Acid Sequence↗

PubMed2000

Metallothioneins in terrestrial invertebrates: structural aspects, biological significance and implications for their use as biomarkers.

During the last few years the subject of metallothioneins (MTs) in terrestrial invertebrates has gained increasing attention. One reason for this may be that terrestrial invertebrates provide new insights into the biological diversity of MTs, with the potential of discovering alternative models of structural and functional relationships. Four groups of terrestrial invertebrates have been studied in detail, namely nematodes, insects, snails and earthworms, with the present article focusing on MTs from the latter two groups. Snails are interesting because they possess distinct MT isoforms involved in different metal-specific tasks. In the Roman snail (Helix pomatia), for example, one isoform is predominantly expressed in the midgut gland, accounting for the accumulation, binding and detoxification of cadmium. The second isoform, which is present in the snail's mantle, is substantially different regarding its primary structure. Furthermore, it binds nearly exclusively copper, and thus is probably involved in the homeostatic regulation of essential trace elements. Earthworm MTs merit our attention because of another peculiarity: they seem to be much more unstable than snail MTs, particularly under conventional conditions of preparation. The cDNA of the brandling worm (Eisenia foetida), for instance, codes for a putative MT, which is about twice the size of the actual protein. The isolated MT peptide binds four Cd2+ ions and represents a one-domain MT entity that is stable and functional in vitro. This strongly suggests that earthworm MTs are either posttranslationally modified, or subjected to enzymatic cleavage during preparation. Both snail and earthworm MTs are inducible by metal exposure, especially by cadmium, thus supporting the idea of using them as potential biomarkers for environmental metal pollution. Whilst snail MTs have already been tested in this respect with some success, the use of earthworm MTs as biomarkers still remains to be evaluated, especially in the light of the unknown significance of their posttranslational instability.

Amino Acid Sequence↗

PubMed2002

Cyclic nitric oxide release by human granulocytes, and invertebrate ganglia and immunocytes: nano-technological enhancement of amperometric nitric oxide determination.

BACKGROUND: Various tissues from vertebrates and invertebrates respond to external signal molecules by rapid release of nitric oxide (NO) mediated by constitutive nitric oxide synthase. MATERIAL/METHODS: Invertebrate immunocytes were collected from maintained stock and human granulocytes were isolated from leukocyte-enriched blood obtained from the Long Island Blood Services. The invertebrate ganglionic tissue was either extracted or exposed for ex vivo and in vivo evaluation. Nitric oxide release was measured using a newly developed NO-selective nanoprobe, exhibiting enhanced sensitivity. RESULTS: Evaluation of NO release from the pedal ganglia of the marine bivalve, Mytilus edulis, demonstrated in vitro release of NO that fluctuated from 969 to 1003 pM, with a mean change in NO of 35 pM/cycle and a mean cycle time of approximately 4 minutes. Basal release of NO/cycle from the ganglia in vivo was increased significantly to approximately 65 pM (P<0.05) with an increase in cycle time to approximately 7 minutes. Exposure of the ganglia to morphine in vivo resulted in a significant increase in NO release and a lack of NO pulsations. The fluctuation in NO release from immunocytes of Mytilus edulis was approximately 27 pM per cycle with a cycle time of 4 minutes whereas human granulocytes release fluctuated approximately 23 pM with a cycle time of 6 minutes. CONCLUSIONS: These data demonstrate that basal release of NO from various tissues is released in a cyclic manner and the cycle time and magnitude is subject to regulation by external stimuli.

Animals↗

PubMed2006

Determination of diphacinone residues in Hawaiian invertebrates.

A reversed-phase ion-pair liquid chromatographic analysis combined with a solid-phase extraction clean-up method is used to assess the quantity of diphacinone residue found in invertebrates. Three invertebrate species are exposed to commercially available diphacinone-fortified bait used for rat control. The invertebrate samples are collected, frozen, and shipped to the laboratory. The samples are homogenized after cryogenic freezing. A portion of the homogenized samples are extracted with acidified chloroform-acetone, followed by cleanup with a silica solid-phase extraction column. Diphacinone is detected by UV absorption at 325 nm after separation by the chromatographic system. The method limit of detection (MLOD) for snail and slug samples averaged 0.055 and 0.066 mg/kg, respectively. Diphacinone residues in snail tissue ranges from 0.83 to 2.5 mg/kg for Oxychilus spp. The mean recoveries from snails at 0.20 and 2.0 are 97 +/- 21% and 84 +/- 6%. Diphacinone residues in slug tissue ranges from 1.3 to 4.0 mg/kg for Deroceras laeve and < MLOD to 1.8 mg/kg for Limax maximus, respectively. The mean recoveries from slugs at 0.20 and 2.0 mg/kg are 91% +/- 15% and 86% +/- 5%.

Animals↗

PubMed1989

A broad evaluation of B.t.i. for black fly (Diptera: Simuliidae) control in a Michigan river: efficacy, carry and nontarget effects on invertebrates and fish.

Efficacy for black fly control, carry and nontarget effects of B.t.i. (Teknar HP-D), applied in the Betsie River, Michigan, were studied in June 1988. Black fly mortality was high (approximately 100%) for a 2,200 m stretch downstream from the application site, declined to 30% at 3,200 m, and was nil at 4,500 m. Drift of black flies greatly increased after application at a downstream site, but did not change at an upstream site. There were no detectable nontarget effects of B.t.i. application on: 1) invertebrate macro- or micro-drift; 2) numbers of invertebrates in benthic Surber samples; 3) mortality or feeding of drifting and nondrifting insects; 4) growth or mortality of caged Stenomena sp. larvae; 5) invertebrate functional group composition; 6) mortality or weight change of caged rock bass; or 7) fish numbers, species composition, length-weight (rock bass only) relationships or rock bass diet. Sampling of Rheotanytarsus sp. midges on natural substrates indicated low (27%) mortality owing to B.t.i. at only 100 m downstream from the application site, with negligible mortality at all other downstream and upstream sites. This information, combined with no pronounced changes in numbers of midges in macro-drift after application, indicated that midge populations were not adversely affected by B.t.i. in the study.

Analysis of Variance↗

PubMed1989

Invertebrate mucous secretions: functional alternatives to vertebrate paradigms.

Invertebrates use mucus in a far broader spectrum of functions than do vertebrates. Examples include: 1. Navigation. The slime trails of grastropods often contain directional information that is used in homing, mating, and predation. 2. Defense. Many invertebrates coat themselves with slippery, distasteful mucus secretions to ward off predators. 3. Desiccation resistance. Limpets and terrestrial snails use a thin barrier of dry mucus as a mechanism for minimizing desiccation. 4. Structural support. Mucus functions as a tensile structural element in feeding nets and mating ropes. A preliminary analysis of these structures indicates that tensile stiffnesses of 10(4)-10(5) N/m2 may be common. 5. Food. The production of mucus can account for up to 80% of the total energy expenditure of some invertebrates. Mucus is often used as a food source, and in some cases is used to enhance the growth of food items. 6. Locomotion. The adhesive locomotion of gastropods is dependent on the unusual mechanical properties of pedal mucus. These properties may set limits to the size and speed of snails and slugs.

Animals↗

PubMed1987

Slugs and snails and opiate tales: opioids and feeding behavior in invertebrates.

There is accumulating evidence that opioid systems are involved in the regulation of fundamental behavioral and physiological processes in invertebrates. Feeding is a basic physiological function that is essential for maintaining homeostasis. Results of studies examining the feeding responses of molluscs and arthropods treated with various opiate agonists and antagonists indicate that delta, kappa, mu, and possibly sigma opioid systems differentially and selectively mediate the components of their natural feeding behavior. Moreover, it appears that at an early evolutionary stage the mu and kappa systems have developed to selectively affect the components of feeding behavior associated with the acquisition and ingestion of food. In addition, evidence suggests that neuropeptides that have been proposed as possible endogenous antagonists of opioid-mediated feeding in mammals may also be involved in the control of feeding in invertebrates. This indicates that there may be an interplay of opioid agonists and antagonists in the regulation of feeding and satiation in invertebrates analogous to that proposed for vertebrates. Moreover, these findings indicate that opioid influences on feeding have been conserved through evolution.

Animals↗

PubMed1987

Consistent synchronization and circaseptennian (about-7-yearly) modulation of circannual gonadal index rhythm of three marine invertebrates.

A circannual rhythm in mean gonadal weight, expressed as percentage of overall body weight, is quantified by cosinor and linear-nonlinear least-squares rhythmometry in three marine invertebrates. Data series from the purple sea urchin (Strongylocentrotus purpuratus), a mollusk, the black chiton (Katharina tunicata), and the ochre sea star (Pisaster ochraceus), exhibiting circannual periods of 368, 361, and 365 days, have relatively tight 95% limits of 356-387, 356-367, and 359-371 days, respectively, when scrutinized by nonlinear least-squares rhythmometry. These limits overlap a precise year (365.25 days). This findings supports the occurrence of a 1 year-synchronized circannual rhythm in these marine invertebrates. For the ochre sea star, the about-yearly timing of greatest gonadal weight in relation to body mass, analyzed for a circannual rhythm by the fitting of a 1-year cosine to the data, remains virtually identical within 30 years. The 95% confidence intervals of the acrophase for mean gonadal weight (as percentage of body weight), range from March 3 to April 12 in the 1950s and from March 8 to April 12 in the 1980s. A MESOR (midline-estimating statistic of rhythm) difference may relate to geographic factors (Pacific Grove, California, from January 1954 to December 1958 vs. Terrace Point near Santa Cruz, California, from December 1978 to June 1985) that in turn may reflect a different food supply and/or temporal factors, e.g., it may result from changes in the ecology of the sea. A possible circaseptennian rhythm is only suspected in the data from the ochre star (P = 0.14); it is rigorously described for the purple sea urchin (P less than 0.001) and also detected in the black chiton (P = 0.029) in time series covering 9.5 years, from September 1953 to April 1963 for the purple sea urchin and from January 1957 to September 1966 for the black chiton. Least-squares rhythmometry (with trial periods between 1 and 15 years in 6-month increments) resolves the two (circannual and circaseptennian) components concomitantly below the 3% level of statistical significance. Nonlinear least-squares rhythmometry validates a period of 7.01 years for the purple sea urchin, although within broad 95% limits (ranging from 5.58 to 10.41 years). The life span of these marine invertebrates is not determined. One deals with a population rhythm sampled with serial independence.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1984

Isolation and characterization of two myoactive neuropeptides: further evidence of an invertebrate peptide family.

The neuropeptide proctolin acts as a neuromuscular co-transmitter in insect skeletal muscle. As a prelude to determining whether other peptides may function in a similar way, we are attempting to isolate and characterize the chemical nature of new myoactive neuropeptides in insects. We examined the corpus cardiacum, a major insect neurosecretory structure of the American cockroach (Periplaneta americana), using a skeletal muscle bioassay and high pressure liquid chromatography fractionation and identified two myoactive factors, MI and MII. They are synthesized in the corpus cardiacum and released from it into the blood by a calcium-dependent mechanism. Amino acid and fast atom bombardment-mass spectroscopy analysis show that MI and MII are structurally related octapeptides representing the major secreted products of the cockroach corpus cardiacum. Both MI and MII are also present in the CNS and in the gut, indicating transmitter as well as hormonal functions in the cockroach. A survey in other species indicates MI may be present in invertebrates other than insects, but neither was found in the rat. The MI and MII peptides have clear chemical affinities to two previously described invertebrate peptides, locust adipokinetic hormone and crustacean red pigment concentrating hormone, as well as sharing biological activity with these peptides. Our results provide further evidence for the existence of a large family of structurally related peptides with divergent functions in a variety of invertebrate types.

Animals↗

PubMed1988

Monoclonal antibodies to the molluscan small cardioactive peptide SCPB: immunolabeling of neurons in diverse invertebrates.

We reported a development of murine monoclonal antibodies to a molluscan small cardioactive peptide (SCPB) and their application to immunolabeling of neurons in several molluscan and arthropod species. In vitro stimulations of mouse lymphocytes with SCPB conjugated to a carrier protein yielded exclusively IgM class antibodies; in vivo stimulation resulted in generation of both IgM and IgG classes of antibodies. Monoclonal antibodies of the IgM class labeled identified SCP-containing neuron B11 in the frozen sections of the buccal ganglia of Tritonia diomedia. These antibodies failed to stain any neurons in whole mount preparations. A monoclonal antibody of IgG1 subclass selectively labeled neurons in both frozen sections and whole mount preparations of diverse invertebrate species. Thus, neurons B11, B12, and GE1 and several other neurons of the buccal and gastroesophageal ganglia of T. diomedia bound the antibody, and a similar pattern of immunolabeling was found in the closely related gastropod Tritonia festiva. We also observed SCPB-like immunoreactivity in the central neurons of other nudibranch and pulmonate molluscs and in examples of insect (Acheta domesticus and Tehrmobia domestica) and crustacean (Semibalanus cariosus) classes of the Arthropoda. Our results suggest a specific pattern of distribution of SCPB-like immunoreactivity in the gastropod nervous system and a broad occurrence of SCPB-like antigenicity in the diverse invertebrates.

Animals↗

PubMedDate not supplied

On the molecular origins of thermal noise in vertebrate and invertebrate photoreceptors.

Retinal photoreceptors generate discrete electrical events in the dark indistinguishable from those evoked by light and the resulting dark signals limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature dependent and in both vertebrate and invertebrate photoreceptors require activation energies usually in the range of 23 to 28 kcal mol-1. Recent molecular orbital studies and pH experiments on horseshoe crabs (Limulus) suggest that the thermal isomerization of a relatively unstable form of rhodopsin, one in which the Schiff-base linkage between the chromophore and protein is unprotonated, is responsible for thermal noise. This mechanism is examined in detail and compared to other literature models for photoreceptor noise. We conclude that this two-step process is likely to be the principal source of noise in all vertebrate and invertebrate photoreceptors. This model predicts that the rate of photoreceptor noise will scale in proportion to 10- xi, where xi is the pKa of the Schiff base proton on the retinyl chromophore. Nature minimizes photoreceptor noise by selecting a binding site geometry which shifts the pKa of the Schiff base proton to > 16, a value significantly larger than the pKa of the chromophore in bacteriorhodopsin (pKa approximately 13) or model protonated Schiff bases in solution (pKa approximately 7).

Animals↗

PubMed2006

Evolution and development of neural circuits in invertebrates.

Developmental mechanisms can shed light on how evolutionary diversity has arisen. Invertebrate nervous systems offer a wealth of diverse structures and functions from which to relate development to evolution. Individual homologous neurons have been shown to have distinct roles in species with different behaviors. In addition, specific neurons have been lost or gained in some phylogenetic lineages. The ability to address the neural basis of behavior at the cellular level in invertebrates has facilitated discoveries showing that species-specific behavior can arise from differences in synaptic strength, in neuronal structure and in neuromodulation. The mechanisms involved in the development of neural circuits lead to these differences across species.

Animals↗