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At least 217 records · Page 12Linked to original sources

PubMed1998

The ecotoxicological significance of genotoxicity in marine invertebrates.

Attention is drawn to the goals of genetic ecotoxicology, in particular, the need to relate genotoxicity in individuals to population and community level consequences. The evidence for pollutant-induced genotoxicity in marine invertebrates is reviewed. Neoplasia is apparently rare in marine invertebrates and only limited evidence is available to suggest that chemical genotoxins act as causative agents. It is unknown why marine invertebrates exhibit low tumour incidences and are much more tolerant of ionising radiation than their vertebrate counterparts. The importance of the genotoxic disease syndrome is highlighted. Disentangling phenotypic manifestations of genotoxic damage and that due to direct metabolic toxicity provides a major challenge for the future. Further work is required to assess the significance of interspecific and interindividual variability in susceptibility to genotoxicity, especially with regard to the evolution of resistant populations and communities of marine organisms at contaminated sites. Only by addressing the issues highlighted above can proper risk assessments of genotoxic agents be performed to minimise threats to human and ecosystem health.

Animals↗

PubMed2002

Fecundity and life-history strategies in marine invertebrates.

The reproductive strategies of an organism play a major role in the dynamics of the population and the biogeography and continuity of the species. Numerous processes are involved in reproduction leading to the production of offspring. Although diverse processes are involved in oogenesis (the production of eggs) and spermatogenesis (the production of sperm), the basic patterns of gametogenesis are similar amongst invertebrates, with the proliferation and differentiation of germ cells leading to the final production of mature gametes. The production of gametes, especially eggs, is energetically expensive, and therefore strongly sensitive to selective pressures. An organism can ingest and assimilate a limited amount of energy from the environment. The different ways by which energy is allocated to growth and reproduction in order to maximize fitness forms the basis of the differing life-history strategies that have developed in marine invertebrates. Fecundity is defined as the number of offspring produced by a female in a determined time period. The term fecundity needs to be explicitly defined in each study in order to obtain the maximum information from the data analysed. Because of the variety of egg production patterns found among marine invertebrates, a wide range of methodologies has been developed to quantify fecundity. These include direct egg counts in brooding species, spawning induction in live individuals and histological studies of preserved material. Specific considerations need to be taken into account for colonial organisms, because of their modular organization. The production of eggs requires an optimal allocation of energy into growth and reproduction for the maximization of parental fitness. Fecundity is central in studies of life-history theory and in the development of life-history models because it is directly related to energy allocation and partitioning. There are important relationships and trade-offs between fecundity and other life-history traits, such as egg size, female size and age, age at first reproduction, reproductive effort and residual reproductive value. These trade-offs, together with morpho-functional constraints and genetic variation determine the evolution of life histories through natural selection. Fecundity is a highly plastic character within the limits defined by the bioenergetics and life-history strategy of the organism. Egg production is affected mainly by environmental factors such as food quantity and quality, temperature or presence of toxic elements in the habitat. The differences in fecundity found among closely related species from different biogeographical locations reflect, at least in part, the differing environmental conditions of their habitat.

Adaptation, Physiological↗

PubMed2003

Invertebrate biomarkers: links to toxicosis that predict population decline.

The application of biochemical measurements that can be used as individual biomarkers of impaired biological function in invertebrates is reviewed to evaluate whether biochemical biomarkers of aquatic invertebrates can predict changes in natural populations. Biomarkers that measure toxic effects at the molecular level (e.g., the inhibition of brain acetylcholinesterase activity by organophosphorus pesticides) have been shown to provide rapid quantitative predictions of a toxic effect upon individuals in laboratory studies. Such biomarkers should not be used as a replacement for conventional aquatic monitoring techniques, but should be applied as supplementary approaches for demonstrating links between sublethal biochemical and adverse effects in natural populations in field studies. The research challenge for using biomarker measurements in aquatic invertebrates is to predict effects at the population level from effects at the individual level measured upon individuals collected in the field.

Acetylcholinesterase↗

PubMed2004

Metabolism of monoamines in invertebrates: the relative importance of monoamine oxidase in different phyla.

A review of the occurrence of monoamine oxidase activity in invertebrates is presented. In contrast to vertebrates, invertebrates use a variety of enzymatic routes to metabolise monoamines. These routes include N-acetylation, gamma-glutamyl conjugation, sugar conjugation, sulphation, beta-alanyl conjugation as well as oxidative deamination. Some of these enzymatic routes appear to be strictly catabolic whereas others result in metabolites used for structural and pigmentation purposes. The development of the various catabolic routes for monoamines in different groups of invertebrates may be dependent on the physical requirements of the diverse excretory organs used by these animals.

Animals↗

PubMed2001

Bioaccumulation of heavy metals in terrestrial invertebrates.

In this literature study, accumulation data of metals in terrestrial invertebrates were collected and compared (Arthropoda and Lumbricidae). Based on total soil concentrations and body concentrations, regression equations were calculated for each metal (Cd, Cu, Pb and Zn) and each taxonomic group. We also tried to find out whether or not accumulation levels of metals in Lumbricidae are representative for all of the studied terrestrial invertebrates. Taxonomic groups could be ordered according to the extent of metal accumulation. Significant differences in accumulation levels of a factor 2-12 were found between taxonomic groups. Overall, metal concentrations were high in Isopoda and low in Coleoptera. The concentrations in Lumbricidae were in between. It should be kept in mind that the data for Lumbricidae were mainly derived from laboratory experiments, while the data for other groups were derived from field studies. The internal Pb, Cd and Cu concentration increased with the soil concentration for most taxonomic groups in the order Pb > Cd > Cu. Body concentrations of Zn were quite constant over a range of soil concentrations. The differences in accumulation level between taxonomic groups show the relevance of including detailed information on feeding behaviour in risk assessment for invertebrate-eating animals.

Animals↗

PubMed2002

Environmental and functional limits to muscular exercise and body size in marine invertebrate athletes.

Many similarities exist between the key characteristics of muscular metabolism in marine invertebrates and those found in vertebrate striated muscle, even though there are important phosphagens and glycolytic end products that differ between groups. Lifestyles and modes of locomotion also vary extremely among invertebrates thereby shaping the pattern of exercise metabolism. In accordance with the limited availability of integrated ecological and physiological information the present paper reports recent progress in the exercise physiology of cephalopods, which are characterized by high rates of aerobic and anaerobic energy turnover during high velocity hunts or escapes in their pelagic environment, and a sipunculid worm, which mostly uses anaerobic resources during extended marathon-like digging excursions in the hypoxic marine sediment. Particular attention is paid to how lifestyle and oxygen availability in various marine environments shapes the use and rates of aerobic and anaerobic metabolism and acidosis as they depend on activity levels and energy saving strategies. Whereas aerobic scope and, accordingly, use of ambient oxygen by blood oxygen transport and skin respiration is maximized in some squids, aerobic scope is very small in the worm and anaerobic metabolism readily used upon muscular activity. Until recently, it was widely accepted that the glycolytic end product octopine, produced in the musculature of these invertebrates, acted as a weak acid and so did not compromise acid-base balance. However, it has now been demonstrated that octopine does cause acidosis. Concomitant study of tissue energy and acid-base status allows to evaluate the contribution of glycolysis, pH and free ADP accumulation to the use of the phosphagen and to the delayed drop in the Gibb's free energy change of ATP hydrolysis. The analysis reveals species specific capacities of these mechanisms to support exercise beyond the anaerobic threshold. During high intensity anaerobic exercise observed in squid, the levels of ATP free energy change finally fall to critical minimum levels contributing to fatigue. Maintenance of sufficiently high energy levels is found at low but extended rates of anaerobic metabolism as observed in the long term digging sipunculid worm. The greatest aerobic and anaerobic performance levels are seen in squid inhabiting the open ocean and appear to be made possible by the uniform and stable physicochemical parameters (esp. high O(2) and low CO(2) levels) that characterize such an environment. It is suggested that at least some squid operate at their functional and environmental limits. In extremely different environments, both the worm and the squids display a tradeoff between oxygen availability, temperature, performance level and also, body size.

Aerobiosis↗

PubMed1998

The fate of organic xenobiotics in aquatic ecosystems: quantitative and qualitative differences in biotransformation by invertebrates and fish.

Biotransformation of natural and man-made foreign compounds (xenobiotics) proceeds via introduction of a functional group (phase I metabolism) and subsequent attachment of a polar moiety to the group (phase II metabolism). The biotransformation fate of xenobiotics depends on the activities, complement and inducibility of the biotransformation enzymes. Previous analysis of the dependence of in vivo rates of biotransformation on tissue parent compound concentration for marine invertebrates revealed that hydrocarbons are metabolised more slowly than xenobiotics already containing functional groups, and crustaceans metabolise both types of xenobiotics faster than molluscs (Livingstone D.R., Persistent pollutants in marine ecosystems, pp. 3-34, Pergamon, Oxford). Use of the same approach showed that fish metabolise pentachlorophenol (PCP) and benzo[a]pyrene (BaP) faster than certain aquatic invertebrates, viz. rates of biotransformation to total metabolites (pmol min-1 g-1 wet wt.) at a tissue parent compound concentration of 10 nmol g-1 were, respectively, 19.2 +/- 3.7 (Carassius auratus) and 4.8 +/- 6.6 (molluscan species) (PCP), and 19.1 +/- 6.3 (fish species) and 2.1 +/- 0.2 (crustacean species) (BaP). The higher rate of biotransformation of BaP in fish is consistent with higher levels of total cytochrome P450 and inducible cytochrome P4501A (CYP1A) activity. The similar rate of metabolism of a hydrocarbon (BaP) (requires initial metabolism by cytochrome P450) and a functional group compound (PCP) by fish may also be due to the high levels of cytochrome P450, compared with the situation in invertebrates where rate-limiting cytochrome P450 may be responsible for the lower rates of hydrocarbon compared with functional group compound metabolism.

Animals↗

PubMed1999

An assessment of the genotoxic impact of the Sea Empress oil spill by the measurement of DNA adduct levels in selected invertebrate and vertebrate species.

The grounding of the Sea Empress oil tanker resulted in the release of 72,000 tonnes of crude oil into Milford Haven, Wales, UK. Our initial studies indicated that this contamination resulted in elevated levels of DNA adducts in one of the area's native marine species Lipophrys pholis [B.P. Lyons, J.S. Harvey, J.M. Parry, An initial assessment of the genotoxic impact of the Sea Empress oil spill by the measurement of DNA adduct levels in the intertidal teleost Lipophrys pholis, Mutat. Res. 390 (1997) 263-268]. These original studies were extended and the genotoxic impact of the oil contamination was investigated in the invertebrates Halichondria panicea and Mytilus edulis, along with the vertebrate fish species L. pholis, Pleuronectes platessa and Limanda limanda. DNA adduct levels were assessed in these species over a period of 2-17 months after the incident. The studies indicate differences in the impact of acute oil contamination upon vertebrate and invertebrate species. The oil contamination did not induce any detectable elevations in adduct levels in the invertebrate species H. panicea and M. edulis. In contrast, the oil contamination did appear to induce adducts in the vertebrate teleost species L. pholis, P. platessa and Lim. limanda. Despite some difficulties in sampling, the data obtained 12-17 months after the spill suggested that the affected species recovered from the oil contamination. While the studies indicate that the genetic impact of the oil contamination was less severe than might have been expected, it remains possible that the DNA adducts detected in the teleosts could lead to genetic changes in these species in the future.

Animals↗

PubMed2001

Toxicity of coelomic fluid of the earthworm Eisenia foetida to vertebrates but not invertebrates: probable role of sphingomyelin.

The coelomic fluid (CF) of the earthworm Eisenia foetida exhibits a wide variety of biological activities. We found that the CF was not toxic to 42 species, belonging to seven invertebrate phyla, almost all in aquatic adults and larvae exposed to CF. Eleven teleostean species tested died in 0.2-1% CF mostly between 10 and 120 min and the effects were dose-dependent. Tadpoles of the toad Bufo japonicus formosus died in 0.4-2% CF between 80 and 225 min depending upon size, with larger tadpoles surviving longer. Before dying, all experimental tadpoles developed curled and shrunken tails. The Okinawa tree lizard, soft-shelled turtle, Japanese quail, mouse and rat all died after i.v. injection of CF (above 20 microl/kg). Thus, CF was not toxic to invertebrates, but toxic to vertebrates. After heating, CF lost its toxicity to fish, tadpoles and mice. Both CF and lysenin incubated with sphingomyelin-liposomes (SM-liposomes) were no longer toxic, suggesting the involvement of SM in the toxicity. Lysenin, which is a constituent of CF and known to bind specifically to sphingomyelin, exhibited toxicity similar to that of CF. Thus, lysenin in CF is probably responsible for the toxic effects of CF by binding to SM in vertebrate tissues. The bodies of invertebrates might contain little or no SM, while those of vertebrates do contain SM. The coelomic fluid of the earthworm Pheretima communissima has no toxicity to mouse.

Animals↗

PubMedDate not supplied

Axonal mRNAs: functional significance in vertebrates and invertebrates.

Sorting of defined mRNA species to distinct cytoplasmic regions is observed throughout the animal kingdom in many cell types, including neurons. During the past years, mRNA localization to dendrites of nerve cells has been characterized in detail. The functional role of these transcripts appears to be obvious: Since dendrites are equipped with the basic translational machinery, certain proteins are likely to be synthesized on-site. Targeting of mRNAs to the axon of vertebrate neurons is less well understood. Even though some vertebrate nerve cells such as goldfish Mauthner neurons seem to have ribosomes within the axonal compartment, evidence for ongoing local translation is still preliminary. In most differentiated mammalian neurons the axon is thought to lack mRNAs and a protein synthesizing machinery. Although a few nerve cell types harbour substantial amounts of distinct mRNA species within the axonal domain, their functional significance has remained elusive until today. Recent evidence suggests that mRNA transport to neurites including the future axon and local translation might play a role in nerve cell maturation. mRNA targeting to the axon of young neurons is strictly correlated with differentiation. It is no longer observed in fully matured neurons. Finally, for many years invertebrate neurons have served as model systems to investigate axonal mRNA transport and its physiological relevance. There is no doubt that protein synthesis does take place in the axonal domain. However, it has to be considered that invertebrate neurons develop only one type of neurite, referred to as the axon. These axons are different when compared with those of vertebrate nerve cells since they combine characteristics of dendrites and axons. In fact, current evidence supports the view that the axonal mRNAs in invertebrate nerve cells have functions comparable to those of transcripts residing in the dendrites of vertebrate neurons.

Animals↗

PubMed2001

Ageing and the nervous system: insights from studies on invertebrates.

Ageing can have profound effects on the post-mitotic organ of behaviour, the brain. As yet the precise causes of these deleterious effects are unknown. However, clear insights into the putative mechanisms and consequences of ageing in the CNS have been achieved through the use of invertebrate models. It is now clear that ageing alters the endogenous properties of neurones, their morphology, the efficacy of the connections that the neurones make with their targets and may even lead to neurone loss. While the precise mechanisms underlying these changes are presently unclear clues from post-mitotic organisms such as C. elegans have provided putative targets which are currently being investigated. It is clear to date that the age-induced changes in CNS function observed in invertebrates are conserved in mammalian species and that further work on invertebrates may provide informative insights in to the mechanisms of neuronal ageing.

Aging↗

PubMed2002

Chemical defense of early life stages of benthic marine invertebrates.

Accurate knowledge of factors affecting the survival of early life stages of marine invertebrates is critically important for understanding their population dynamics and the evolution of their diverse reproductive and life-history characteristics. Chemical defense is an important determinant of survival for adult stages of many sessile benthic invertebrates, yet relatively little consideration has been given to chemical defenses at the early life stages. This review examines the taxonomic breadth of early life-stage chemical defense in relation to various life-history and reproductive characteristics, as well as possible constraints on the expression of chemical defense at certain life stages. Data on the localization of defensive secondary metabolites in larvae and the fitness-related consequences of consuming even a small amount of toxic secondary metabolites underpin proposals regarding the potential for Müllerian and Batesian mimicry to occur among marine larvae. The involvement of microbial symbionts in the chemical defense of early life stages illustrates its complexity for some species. As our knowledge of chemical defenses in early life stages grows, we will be able to more rigorously examine connections among phylogeny, chemical defenses, and the evolution of reproductive and life-history characteristics among marine invertebrates.

Adaptation, Physiological↗

PubMed2004

Doubling the estimate of invertebrate biomass in a rainforest canopy.

Forest canopies represent the functional interface between 90% of the Earth's terrestrial biomass and the atmosphere and include some of the most threatened of all terrestrial ecosystems. However, we lack even a basic understanding of how the biomass of plants and animals is distributed throughout forest canopies, even though this information is vital for estimating energy flow, carbon cycling, resource use and the transfer of materials within this ecosystem. Here we measure the biomass of invertebrates living in a common rainforest epiphyte, describe a striking relationship between fern size and the biomass of animals within the ferns, and reveal that one large epiphyte may contain an invertebrate biomass similar to that found in the whole of the rest of the tree crown on which it is growing. Using these data, we show that including the fauna of these epiphytes--a neglected component in rainforest ecosystems--can more than double our estimate of the total invertebrate biomass in an entire rainforest canopy.

Animals↗

PubMed2004

Invertebrates as a source of emerging human pathogens.

Despite their importance, little is known about the origins of many emerging human pathogens. However, given the age and current predominance of invertebrates, it is likely that bacteria-invertebrate interactions are not only a present source of human pathogens but have also shaped their evolution. Pathogens of invertebrate and unicellular organisms represent an extensive reservoir of bacterial strains equipped with virulence factors that evolved to overcome the innate immune responses of their hosts. This reservoir might represent a source of new human pathogenic strains and might also foster the spread of novel virulence factors into existing human commensal or pathogenic bacteria. This article examines the available evidence for this concept by examining pairs of closely related bacteria, one of which is benign, but insect associated, and one of which is a human pathogen.

Animals↗

PubMed1999

Invertebrates versus vertebrates innate immunity: In the light of evolution.

Invertebrates use a nonadaptive, innate immunity, the expression of germline encoded receptors, to identify the allogeneic and xenogeneic attributes. Vertebrates also have the capacity to express ontogenically related adaptive immunity which is a somatically selected gene rearrangement process. Several commonly accepted generalizations are utilized to explain the enigmatic lack of the adaptive immunity in invertebrates. All point to the primitive nature of the innate immunity and the primitive organization of the body plan and the life history patterns of invertebrates. Seven of the most common generalizations are reviewed and confuted by virtue of a biased literature presentation. Subsequently, three evolutionary puzzles are raised and the accepted paradigm that the vertebrate immunity is pathogenically directed is further challenged. This leads to an alternative idea suggesting that preserving the individuality against the threat of invading conspecific cells might have been the original function of the immune system. This ancient system has been co-opted later on to serve as a defence mechanism against pathogens. The secondary role arose in the form of a multiplicity of newly developed phenomena, one of them being the vertebrate adaptive immunity. This proposal is supported by the fact that vertebrates still exhibit two distinct but common types of naturally occurring transplantation events (natural chimerism) and by a variety of recent studies, providing evidence for the crucial role of the vertebrate's innate immunity in signalling and triggering the acquired effector mechanisms.

Adaptation, Physiological↗

PubMed2006

Ion regulation in invertebrates: molecular and integrative aspects.

The subject of ion regulation in invertebrates is discussed, using a variety of invertebrate model species and approaches that range from the whole-organism level to tissue, subcellular, and molecular levels to illustrate the future direction of the field. These organisms inhabit a variety of aquatic, freshwater, and terrestrial environments, showing specific adaptations to each environment. This overview discusses mechanisms of metal detoxification and the presence of Cl-ATPase in marine organisms to avoid excess intracellular Cl(-); Ca(2+) regulation and endocrine aspects of adaptations to transitional (semiterrestrial) environments; adaptations to Ca(2+)-poor freshwater, particularly the reabsorption of Ca(2+) through specific transporters found in the urine; and finally, ionoregulatory mechanisms for life on land, such as Ca(2+) conservation during molting in isopods and the presence of K(+) channels in insect Malpighian tubules. Convergent mechanisms for dealing with similar problems in dissimilar habitats are discussed, taking into consideration that invertebrates will continue to serve as model systems for the evolution of ionoregulation in different habitats.

Adaptation, Physiological↗

PubMed1998

Immunology of human implantation: from the invertebrates' point of view.

Pregnancies in outbred mammals may be regarded as successfully developed homografts. One of the hypotheses that attempts to answer the enigma of why the fetus is not rejected (fetal-maternal relationships are based on reciprocal expressions of foreign transplantation antigens) claims for the existence of possible evolutionary links between invertebrate allorecognition and mammalian implantation, based on some cellular similarities. This essay further discusses the possible evolutionary perspectives between vertebrates and invertebrates alloimmunities from a different viewpoint. We discuss similarities between natural transplantation in colonial marine invertebrates, which are followed by chimerism and a state of tolerance, and two natural transplantation events in the mammalian systems which both have records for prolonged chimerism and tolerance: the phenomenon of dizygotic twin fusions and the situation of fetal cells implantation. Earlier comparative evolutionary perspectives are revisited.

Animals↗

PubMed1991

Endothelin-like immunoreactivity in the nervous system of invertebrates and fish.

There have been no reports on the distribution of immunoreactive endothelin (ir-ET) in lower vertebrates and invertebrates, except for our previous studies on the nereid Neanthes diversicolor and the earthworm Eisenia foetida. In the present study, we found ET-like immunoreactivity in five species of invertebrates and two species of fish with antiserum against synthetic endothelin-1 (ET-1). Immunoreactive perikarya and nerve fibers were observed in the central nervous system of the slug Limax marginatus, the freshwater snail Indoplanorbis exustus, and the mussel Mytilus edulis in mollusks, the field cricket Gryllus bimaculatus in insects, and the tube tunicate Ciona intestinalis in protochordates. In the medaka, Oryzias latipes, ir-ET was found in the hypothalamoneurohypophysial system, the caudal neurosecretory system, the gill, and the kidney. Immunoreactive cells were also found in the mucous gland of the slug and in the adenohypophysis of the lamprey, Lampetra japonica. The wide distribution of ET-like substances in invertebrates and fish provides evidence for the case that ET found in mammals has a long evolutionary history.

Animals↗