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Climate change driven ocean acidification and hypercapnia may have a negative impact on fertilization in marine organisms because of the narcotic effect these stressors exert on sperm. In contrast, warmer, less viscous water may have a positive influence on sperm swimming speed and so ocean warming may enhance fertilization. To address questions on future vulnerabilities we examined the interactive effects of near-future ocean warming and ocean acidification/hypercapnia on fertilization in intertidal and shallow subtidal echinoids (Heliocidaris erythrogramma, H. tuberculata, Tripneustes gratilla, Centrostephanus rodgersii), an asteroid (Patiriella regularis) and an abalone (Haliotis coccoradiata). Batches of eggs from multiple females were fertilized by sperm from multiple males in all combinations of three temperature and three [Formula omitted] treatments. Experiments were placed in the setting of projected near-future conditions for southeast Australia, an ocean change hot spot. There was no significant effect of warming and acidification on the percentage of fertilization. These results indicate that fertilization in these species is robust to temperature and [Formula omitted] fluctuation. This may reflect adaptation to the marked fluctuation in temperature and pH that characterises their shallow water coastal habitats. Efforts to identify potential impacts of ocean change to the life histories of coastal marine invertebrates are best to focus on more vulnerable embryonic and larval stages because of their long time in the water column where seawater chemistry and temperature have a major impact on development., Author(s): Maria Byrne [sup.1] , Natalie A. Soars [sup.2] , Melanie A. Ho [sup.2] , Eunice Wong [sup.2] , David McElroy [sup.2] , Paulina Selvakumaraswamy [sup.2] , Symon A. Dworjanyn [...]

Extreme summertime flood events are expected to become more frequent in European rivers due to climate change. In temperate areas, where winter floods are common, extreme floods occurring in summer, a period of high physiological activity, may seriously impact floodplain ecosystems. Here we report on the effects of the 2002 extreme summer flood on flora and fauna of the riverine grasslands of the Middle Elbe (Germany), comparing pre-and post-flooding data collected by identical methods. Plants, mollusks, and carabid beetles differed considerably in their response in terms of abundance and diversity. Plants and mollusks, displaying morphological and behavioral adaptations to flooding, showed higher survival rates than the carabid beetles, the adaptation strategies of which were mainly linked to life history. Our results illustrate the complexity of responses of floodplain organisms to extreme flood events. They demonstrate that the efficiency of resistance and resilience strategies is widely dependent on the mode of adaptation. Key words: carabid beetles; extreme event; flood; floodplain; grassland; mollusks; resilience; resistance; river Elbe; vegetation.

Tools from metabolic scaling and food web theory were used to construct a general model of carbon flux by litter and soil invertebrates. The flux model was used to explore the energetic basis of invertebrate abundance and predicted that abundance should (1) scale linearly with net primary production; (2) be related to the body mass of animals as a power function, with an exponent between -0.65 and -0.85; (3) be related to the average body temperature of animals according to the Boltzmann factor, with an activation energy between 0.27 and 0.79 eV; and (4) decrease by a factor of 0.05 to 0.15 across trophic levels due to gross production efficiency of prey. Model predictions were generally supported by a global data set on invertebrate abundance that was amassed during the International Biological Programme, indicating that fundamental energetic principles explain a large degree of variation in invertebrate abundance across the globe. Key words: abundance; arthropods; body mass; body temperature; International Biological Programme; invertebrates; metabolic scaling theory; net primary production; trophic level.

I. Introduction A. Why study invertebrate muscles, genes, and proteins? B. Invertebrate and vertebrate phylogeny C. Scope of review and literature database II. Review of Vertebrate Muscle Specific Proteins III. [...]

The copepod Paramacrochiron maximum was found in high numbers (up to 5,675 copepods/medusa) on the oral arms of the scyphozoan Catostylus mosaicus. This association was considered to be commensalism for the following reasons: P. maximum (Lichomolgidae) was abundant on the medusae (approximately 805 copepods/kg of medusae) and very rare in the water column (approximately 5.99 x 10-4 copepods/kg of water); copepodites and adults of the symbiont were present on the host; the copepods were on the medusae both day and night, at different times (nine occasions between March 1999 and May 2000) and diffferent locations (Botany Bay and Lake Illawarra, NSW, Australia). Over 40 taxa of plankton were found on the oral arms of C. mosaicus (including protists, cnidarians, polychaetes, molluscs, a wide range of holoplanktonic and meroplanktonic crustaceans, chaetognaths and fish eggs). These taxa were abundant in the water column and we concluded that they were prey. Symbiotic amphipods and carangid fishes were found with medusae. We conclude that there is a symbiotic association between P. maximum and C. mosaicus and care should be taken not to confound these copepods with the prey of C. mosaicus. Poecilostomid copepods are well known for consuming mucus and feeding is likely to be a major reason for the association., Introduction The nature of interactions between scyphozoans and invertebrates can vary greatly (Kingsford et al. 2000). There are examples of parasitism (Phillips et al. 1969), commensalism (Bruce 1988) and predator-prey [...]

Invertebrate prey have been shown to select suboptimal resource patches in the face of predation (the food-predation risk trade-off). The foraging strategy used by a predator and the environmental context under which an interaction occurs potentially mediates prey responses to predators. Here, I determined whether season, predator presence or alternative prey availability affected prey patch use when faced with a sit-and-wait predator from streams in southern Maine. In addition, instantaneous mortality rates and predator movement behavior were assessed as possible mechanisms explaining patch use by prey in different seasons. In the absence of predators, prey did not show any preference for substrate patches based on particle size. But, depending on prey type and season, substrate position in streams had a significant effect on prey survival. Mayflies survived most in summer when pebble substrates were located upstream whereas caddisfiy survival was highest when pebble substrates were located downstream in winter. Season and taxa significantly affected instantaneous mortality rates, suggesting this predator responded differently to available prey in each season. Predators changed ambush positions in the streams significantly more during winter than during summer, both with and without prey present. The presence of caddisflies in mixed-prey trials reduced consumption of mayflies in summer, but increased their mortality in winter. Increased movement behavior of predators in winter may have led to greater encounters with prey, thus increasing winter mortality. Collectively, these data reveal season can influence the outcome of predator-prey interactions. Environmental context, as well as predation mode, is critical to predicting predation effects in macroinvertebrate communities. Further studies of the seasonal changes in organism-specific behavior are needed to evaluate the importance of biotic interactions in structuring stream communities.

The ecophysiology of cold tolerance in many terrestrial invertebrate animals is based on water and its activity at low temperatures, affecting cell, tissue and whole organ ism functions. The normal [...]

We here describe the cloning and characterization of the functionally active Drosophila melanogaster (Drm) FMRFamide receptor, which we designated as DrmFMRFa-R. The full-length ORF of a D. melanogaster orphan receptor, CG 2114 (Berkeley Drosophila Genome Project), was cloned from genomic DNA. This receptor is distantly related to mammalian thyroid-stimulating hormone-releasing hormone receptors and to a set of Caenorhabditis elegans orphan receptors. An extract of 5,000 central nervous systems from the related but bigger flesh fly, Neobellieria bullata (Neb), was used to screen cells expressing the orphan receptor. Successive purification steps, followed by MS, revealed the sequence of two previously uncharacterized endogenous peptides, APPQPSDNFIRFamide (Neb-FIRFamide) and pQPSQDFMRFamide (Neb-FMRFamide). These are reminiscent of other insect FMRFamide peptides, having neurohormonal as well as neurotransmitter functions. Nanomolar concentrations of the Drm FMRFamides (DPKQDFMRFamide, TPAEDFMRFamide, SDNFMRFamide, SPKQD-FMRFamide, and PDNFMRFamide) activated the cognate receptor in a dose-dependent manner. To our knowledge, the cloned DrmFMRFa-R is the first functionally active FMRFamide G protein-coupled receptor described in invertebrates to date.

The kelp Laminaria hyperborea provides a habitat for a diverse invertebrate community. Invertebrate abundance is particularly high in the kelp holdfasts and associated with epiphytes on the stipes. We investigated colonisation patterns of this fauna on artificial substrata (holdfast and epiphyte mimics) exposed for short time periods in the kelp forest in two seasons, summer and late autumn. Within 7 days, 99 taxa common on natural kelp substratum colonised the artificial substrata in large numbers, demonstrating high mobility and indicating that there may be a rapid exchange of individuals and species among algae. Gastropods and amphipods were the most abundant colonisers. In summer, a specific 'epiphyte fauna' could be distinguished from a 'holdfast fauna', and species associated with epiphytes were significantly more abundant on the artificial substrata. Colonisation was more rapid in summer than in late autumn, which may be related to animal population density. The high dispersal rate can facilitate the interaction with other communities and with higher trophic levels in the kelp-forest food web.

FMRFamide and FMRFamide-related neuropeptides are extremely widespread and abundant in invertebrates and have numerous important functions, Here, we have cloned a Drosophila orphan receptor, and stably expressed it in Chinese hamster ovary cells. Screening of a peptide library revealed that the receptor reacted with high affinity to FMRFamide (E[C.sub.50], 6 x [10.sup.-9] M). The intrinsic Drosophila FMRFamide peptides are known to be synthesized as a large preprohormone, containing at least 13 related FMRFamide peptides (8 distinct FMRFamides). Screening of these intrinsic Drosophila FMRFamides showed that the receptor had highest affinity to Drosophila FMRFamide-6 (PDNFMRFamide) (E[C.sup.50], 9 x [10.sup.-10] M), whereas it had a somewhat lower affinity to Drosophila FMRFamide-2 (DPKQDFMRFamide) (E[C.sub.50], 3 x [10.sup.-9] M) and considerably less affinity to the other Drosophila FMRFamide-related peptides. To our knowledge, this article is the first report on the molecular identification of an invertebrate FMRFamide receptor.

We describe two applications of a recently introduced system for very precise, continuous measurement of water oxygen saturation. Oxygen microoptodes (based on the dynamic fluorescence quenching principle) with a tip diameter of ~50[micro]m, an eight-channel optode array, an intermittent flow system, and online data registration were used to perform two types of experiments. The metabolic activity of Antarctic invertebrates (sponges and scallops) was estimated in respiration experiments, and, secondly, oxygen saturation inside living sponge tissue was determined in different flow regimes. Even in long-term experiments (several days) no drift was detectable in between calibrations. Data obtained were in excellent correspondence with control measurements performed with a modified Winkler method. Antarctic invertebrates in our study showed low oxygen consumption rates, ranging from 0.03-0.19 [cm.sup.3] [O.sub.2] [h.sup.-1] [ind.sup.-1]. Oxygen saturation inside living sponge specimens was affected by flow regime and culturing conditions of sponges. Our results suggest that oxygen optodes are a reliable tool for oxygen measurements beyond the methodological limits of traditional methods.

Silicon is essential for some plants, diatoms, and sponges but, in higher animals, its endogenous regulation has not been demonstrated. Silicate ions may be natural ligands for aluminum and here we show that, in the freshwater snail (Lymnaea stagnalis), intracellular silicon seems specifically up-regulated in response to sublethal aluminum exposure. X-ray microanalysis showed that exposure of snails to low levels of aluminum led to its accumulation in lysosomal granules, accompanied by marked up-regulation of silicon. Increased lysosomal levels of silicon were a specific response to aluminum because cadmium and zinc had no such effect. Furthermore, intra-lysosomal sulfur from metallothionein and other sulfur-containing ligands was increased after exposure to cadmium and zinc but not aluminum. To ensure that these findings indicated a specific in vivo response, and not ex vivo formation of hydroxy-aluminosilicates (HAS) from added aluminum (555 [micro]g/ liter) and water-borne silicon (43 [micro]g/liter), two further studies were undertaken. In a ligand competition assay the lability of aluminum (527 [micro]g/liter) was completely unaffected by the presence of silicon (46 [micro]g/liter), suggesting the absence of HAS. In addition, exogenous silicon (6.5 mg/liter), added to the water column to promote formation of HAS, caused a decrease in lysosomal aluminum accumulation, showing that uptake of HAS would not explain the loading of aluminum into lysosomal granules. These findings, and arguments on the stability, lability, and kinetics of aluminum-silicate interactions, suggest that a silicon-specific mechanism exists for the in vivo detoxification of aluminum, which provides regulatory evidence of silicon in a multicellular organism.

After infection with the digenetic trematode Echinostoma paraensei, hemolymph of the snail Biomphalaria glabrata contains lectins comprised of 65-kDa subunits that precipitate polypeptides secreted by E. paraensei intramoiluscan larvae. Comparable activity is lacking in hemolymph of uninfected snails. Three different cDNAs with sequence similarities to peptides derived from the 65-kDa lectins were obtained and unexpectedly found to encode fibrinogen-related proteins (FREPs). These FREPs also contained regions with sequence similarity to Ig superfamily members. B. glabrata has at least five FREP genes, three of which are expressed at increased levels after infection. Elucidation of components of the defense system of B. glabrata is relevant because this snail is an intermediate host for Schistosoma mansoni, the most widely distributed causative agent of human schistosomiasis. These results are novel in suggesting a role for invertebrate FREPs in recognition of parasite-derived molecules and also provide a model for investigating the diversity of molecules functioning in nonself-recognition in an invertebrate.

Recent work shows that glial cells in species throughout the animal kingdom appear to contribute to the functioning of the neurones and are equipped to receive signals from them. However, the detailed mechanisms of the signalling and its role in vivo are generally unclear. Parts of some invertebrate nervous systems are particularly favourable for addressing these problems, and the four preparations that have been studied most intensively are the subject of this review. Between the giant axons and their Schwann glial cells in squid and crayfish, within snail brain, and in leech ganglion, there appear to be multiple, and in some cases very complex, signalling pathways, whose precise functions remain to be elucidated. In bee retina only a single signal to the gila has been demonstrated, and its function appears to be to activate transfer of metabolic substrates to the photoreceptor neurones. Trends Neurosci. (1996) 19, 358-362

Recent studies on the mechanisms of neuronal connectivity in both vertebrate and invertebrate systems suggest that chemotactic factors play an important role in neuronal target recognition. Neurons select a unique target from a set of diverse cell types based on the expression of recognition molecules. A molecular approach proposes that cell surface and secreted proteins control target specificity. A biochemical approach proposes that specific receptors on the growth cone of axons translate signals that determine neuronal movements and responses.

Laboratory experiments varying gamete concentrations and gamete age demonstrated significant reductions in fertilization success of the starfish Acanthaster planci (L.) with decreasing sperm concentration and increasing age of both eggs and sperm. The effect of aging in sperm was faster than that of eggs, and the speed of sperm aging increased with increasing dilution of sperm. Fertilization success was high over a wide range of sperm: egg ratios but declined rapidly at ratios less than 50, particularly at low sperm concentrations. A. planci gametes aged more slowly, and the loss of fertilizing capacity of sperm with dilution (the respiratory dilution effect) was far less, than in sea urchins. These characteristics provide a mechanism for enhanced fertilization success at given sperm concentrations and at greater distances and times from the point of gamete release, and may explain the higher fertilization rates achieved over longer distances in the wild by A. planci relative to sea urchins. Gametes would remain competent for longer periods at more dilute concentrations and so better achieve long-distance fertilization. Gametes obtained at the end of the breeding season were qualitatively different from those obtained early in the breeding season and showed reduced fertilization success for a given combination of variables, and different fertilization dynamics.

A review of body odor-mediated behaviors of hermit crabs, predatory gastropods, barnacle larvae and brachyuran crabs includes a model based on the hypothesis that all the behaviors are mediated by a similar chemical detection mechanism. A key assumption is behaviors evolved due to a selective advantage conferred by detection of information in body odors. In the model, exogenous trypsin-like proteases digest structural proteins to generate neutral-basic peptides. The receptor is postulated to have resulted from a point mutation in a trypsin-like membrane protein. Transduction of the binding event is via second messenger mediated pathways. Examples of body odors functioning as cues, allomones and pheromones are presented. The model is supported by a review of structure-function studies employing synthetic neutral basic peptides and studies with other macromolecules.

Specialized glands that release formed secretions of a complex structure are known from several invertebrate phyla. A novel type of such an extrusive organ has been detected in the newly described Antarctic entoproct Loxosomella brochobola Emschermann, 1993 and is reported here. The specialized extrusive organs known from other invertebrates are generally unicellular, but these entoproctan glands are multicellular organs. The structured secretion of these glands is an extracellular product homologous to the body cuticle and is discharged in long sticky, hollow threads. In evolutionary convergence to the glutinant spirocysts of the Anthozoa, these threads are assumed - like set out single lime-twigs - to trap larger prey organisms inaccessible to the ciliary feeding current of the entoproct. Specialized glands of this kind have not been known previously in Entoprocta. This 'invention' by a nanoplankton feeder must be seen as a specific adaptation to life in an environment that is poor in nanoplankton. L. brochobola was found exclusively on the inner, abfrontal surface of the tube-shaped, calcareous colonies of the bryozoon Porella malouinensis and shares this microhabitat only with some smaller predators, such as the hydrozoan Halecium sp.; no other ciliary feeders are present.

Studies regarding invertebrate cDNA clones for gamma aminobutyric acid (GABA) and glutamate receptors are relatively few compared to those conducted for vertebrates. In 1991 however, two GABA receptor polypeptides and two glutamate receptor polypeptides were isolated from the mollusc Lymnaea stagnalis and the insect Drosophila melanogaster. These, combined with discoveries of one of the clone's pharmacological properties, are expected to contribute significantly to further research concerning invertebrate ion channel protein electrophysiology and phramacology.

3,4-Dihydroxyphenylalanine (DOPA) occurs transiently in nature as a free or peptide-bound amino acid. It is probably universally distributed in tissues and fluids of invertebrates. DOPA is a highly versatile metabolite, participating in neuroendocrine, immune, and reproductive functions, as well as in the formation of such products as bioadhesives, silks, integuments, and pigments. The mechanism by which DOPA is formed from tyrosine or peptidyl tyrosine remains to be determined in most cases. Future advances in DOPA chemistry may lead to a better understanding of the resonance between structural and sensory functions in animals.

Hemoglobins, found in members of almost all invertebrate phyla, display an extraordinary diversity of form and function. Although some are intracellular with chains and assemblies similar in size to those of vertebrates, others are giant extracellular proteins with masses as large as 8,000 kilodaltons. Two very different strategies have evolved for the stabilization of these large molecules. The first is the formation of both intra- and inter- chain disulfide bonds that effectively immobilize segments of the protein, and the second is the evolution by gene duplication of multi-domain chains with from two to eighteen myoglobin-like, heme-containing domains in a single polypeptide that may be as large as 260 kilodaltons. The genes for vertebrate globins have a characteristic two-intron, three-exon structure. The gene encoding chain c of the hemoglobin of the earthworm Lumbricus terrestris has precisely the same organization and splice junction positions. This shows that these positions have been conserved for at least 600 million years, the estimated time of divergence of annelids and the ancestor to chordates. The gene encoding a hemoglobin (leghemoglobin) of higher plants shows exactly the same splice junctions as in the globin genes of vertebrates except that the middle exon is split by an additional intron which is believed to have been lost early in animal evolution. The occurrence of hemoglobins in diverse higher plants suggests that they might be present in all plants albeit at very low concentrations and perhaps serving an enzymatic function. Hemoglobin, broadly defined as a heme-containing protein capable of reversible combination with oxygen, also occurs in bacteria and fungi. The discovery of a bacterial hemoglobin that is 26% identical with lupin leghemoglobin indicates a procarvotic origin. The possibility that hemoglobin may have evolved from a cytochrome is suggested by the presence of hemoglobins in the yeast, Candida, and the bacterium, Alcaligenes, that contain both heme and flavin. They must therefore have evolved by the fusion of the genes for two different proteins. However, the possible homology of the heme domains with plant or animal hemoglobins remains to be determined. The lactic dehydrogenase of yeast, cytochrome [b.sub.5], is also a soluble flavoheme protein with a heme domain that is homologous with mammalian cytochrome [b.sub.5]. Globin may have evolved in part from a member of the cytochrome [b.sub.5] family, but if so, the event must have occurred so early that only a borderline perhaps random correspondence of amino acid sequences remains.

The statistical approach to test the significance of phylogeographic subdivisions and assess the power to detect the genetic isolation by distance pattern was used to understand the specific case of hydrothermal vent invertebrates. The low statistical power associated with the sampling effort explained the failures to detect evidence for isolation-by-distance (IBD) and the simulation methods proposed could also find potential application for testing the significance of inferred phylogeographic gaps in other species.

The bioaccumulation of chromium and selenium at dangerous levels in the invertebrate prey of lesser as well as greater scaup in north America has led to the decline of the scaup populations.

Heart rate of invertebrates when exposed to predator and nonpredator threat is presented. Impact of the physical environment in such a situation is discussed. Aequipecten opercularis, a juvenile queen scallop, and Asterias rubens, a common starfish is used as proxies for the experiment.

Since the discovery that methyl farnesoate (MF), the unepoxidated form of the insect juvenile hormone (JHIII), is produced by mandibular organs of numerous crustaceans, extensive evidence has accumulated that this compound appears to perform similar functions in the Crustacea as JH performs in insects. A major function of MF appears to be in enhancing reproductive maturation. This was first shown by indirect experimentation with eyestalk ablation, which augmented MF production. Subsequently, direct treatments of several species of crustacea with MF showed that reproductive maturation was enhanced. A second function of MF, similar to that of the JH of insects, is in the maintenance of juvenile morphology. This is especially true in the late larval transformations into juveniles, where MF plays an inhibitory role, as well as during the transformation of juveniles into adults. These results were inferred from eyestalk removal experiments. In the case of the larval-juvenile transition, inhibitory results were also obtained with MF by direct hormone treatments. However, the transition from very early larval stages, such as one nauplius stage proceeding to the next, which in many cases also involves morphogenetic changes, may be occurring in the presence of MF. Indeed, MF appears to be stimulatory to early postembryonic larval stages of Crustacea. Again, this function of MF in Crustacea appears to be similar to functions of JH in early postembryonic insects. However, it should be pointed out that there are many more 'early' stages in Crustacea than there are in insects, and very few of these cases have been investigated. When considering the animal kingdom and larval metamorphosis, the question may be raised whether there are other members of the JH family regulating metamorphosis and reproduction. One plausible example appears to be among certain annelids. The trochophores of Capitella respond to various juvenoids, but are most responsive, within one hour, to MF and eicosatrienoic acid. This latter compound is present also in adult annelids, where it has been named 'Sperm Maturation Factor,' since it seems to function in the maturation of sperm in Arenicola. Therefore, eicosanoids perform in annelids two functions performed in insects by JHs. In conclusion, it seems that there are morphogenesis promoting responses to JHs in early larval development in crustaceans, annelids, and possibly other forms, which differ from those MF effects in later larvae of Crustacea where MF retards morphogenesis. Such early responses as noted here have recently also been described for insects. Furthermore, it is clear that the polyunsaturated 8,11,14-eicosatrienoic and aracidonic acids seem to be juvenoids, and appear to function as such in annelids, and may also be functionally active in insects and crustaceans. It seems reasonable to conclude therefore that new and novel juvenoids exist, while others still await discovery.

Cell cycle progression and cell division are sensitive to hypoxia in Drosophila melanogaster embryos. Am J Physiol Regulatory Integrative Comp Physiol 280: R1555-R1563, 2001.--We and others recently demonstrated that Drosophila melanogaster embryos arrest development and embryonic cells cease dividing when they are deprived of [O.sub.2]. To further characterize the behavior of these embryos in response to [O.sub.2] deprivation and to define the [O.sub.2]-sensitive checkpoints in the cell cycle, embryos undergoing nuclear cycles 3-13 were subjected to [O.sub.2] deprivation and examined by confocal microscopy under control, hypoxic, and reoxygenation conditions. In vivo, real-time analysis of embryos carrying green fluorescent protein-kinesin demonstrated that cells arrest at two major points of the cell cycle, either at the interphase (before DNA duplication) or at metaphase, depending on the cell cycle phase at which [O.sub.2] deprivation was induced. Immunoblot analysis of embryos whose cell divisions are synchronized by inducible String (cdc25 homolog) demonstrated that cyclin B was degraded during low [O.sub.2] conditions in interphase-arrested embryos but not in those arrested in metaphase. Embryos resumed cell cycle activity within ~20 min of reoxygenation, with very little apparent change in cell cycle kinetics. We conclude that there are specific points during the embryonic cell cycle that are sensitive to the [O.sub.2] level in D. melanogaster. Given the fact that [O.sub.2] deprivation also influences the growth and development of other species, we suggest that similar hypoxia-sensitive cell cycle checkpoints may also exist in mammalian cells. green fluorescent protein-kinesin; cell cycle arrest; [O.sub.2] deprivation; invertebrates; metaphase; S phase

Wolbachia are a widespread group of bacteria that commonly found in insects, isopods, arachnids and nematodes. These cytoplasmically inherited bacteria cause a number of alterations in host reproduction, including induction of sperm-egg incompatibility, parthenogenesis, feminization of genetic males, and male-killing. These alterations enhance transmission of the bacteria within host populations. Wolbachia may also have evolved mutualistic interactions with hosts. These bacteria are capable of moving between distantly related host taxa by mechanisms that are as yet unclear. It has been proposed that these bacteria may play a role in rapid speciation in invertebrates; however, this view is controversial. Information is presented on the evolutionary biology of these fascinating bacteria. In addition, theoretical and empirical studies relating to the possible role or Wolbachia in host speciation is discussed.

Muscle can serve a role in stabilization to rapid perturbations. Intrinsic muscle properties may result in a stabilizing response acting before reflexes, hence termed a preflex (Loeb and Brown, 1996). To investigate the stabilizing properties of muscle, we measured mechanical impedance of two leg muscles used by the cockroach, Blaberus discoidalis. Experiments consisted of ramp stretches (0.5-4%; 0.1-5 lo/sec) and sinusoidal length oscillations (5-150 Hz; 0.5% strain; muscle length 90-130% lo) that were imposed on active as well as relaxed muscles. The force response to perturbations in relaxed muscle was a significant fraction (10-50%) of that observed in active muscle. Impedance (delta force/delta length) of relaxed muscle doubled over the range of frequencies, whereas it increased 5-fold with a 40% increase in muscle length. The tangent of phase angle ranged from 0.2-0.6, indicating significant damping. The contribution of leg muscles toward rejecting perturbations could be substantial and in part due to passive mechanisms. The relative importance of active and passive preflexes to stability will require a multiple muscle model which includes moment arms to yield apparent joint stiffness and damping. ONR N00014-98-1-0669.

In shallow-water marine invertebrates, osmotic balance depends on organic osmolytes, usually free amino acids such as glycine, alanine, taurine. Recently we showed that muscles of some deep-sea crustaceans, anemones, squid and bivalves are dominated by trimethylamine oxide (Kelly and Yancey, Biol. Bull. 196:18, 1999). We have now examined other deep-sea invertebrates. In vestimentiferan vestiment tissue, hydrothermalvent Riftia were dominated by hypotaurine (an antioxidant) and cold-seep Lamellibrachia were dominated by N-methyltaurine (up to 190 mmol/kg wet wt.), identified by HPLC and NMR. Muscles of four sea cucumber, one sea urchin and two gastropod species had high contents of scyllo-inositol (up to 90 mmol/kg wet wt.), identified by HPLC and GC-MS. To our knowledge none of these solutes have previously been reported at high levels in any organism, and the inositol is the first major carbohydrate osmolyte reported for a marine invertebrate. We thank C. Fisher and G. Somero for samples. Supported by the M.J. Murdock Charitable Trust and The University of Otago.

Nitric oxide is not just the free radical gas that scientists once regarded it as. Rich radox chemistry of the diatomic NO gives this molecule the functional flexibility to interact with both metal and non-metal components of biological molecules and thereby allow for allosteric control. Many of the basic discoveries linking NO to biological systems have arisen from structure-function relationships in hemoglobin (Hb). For example by analogy with Hb Lou Ignarro in a now-classic papers on NO proposed that the activation of soluble guanylate cyclase occurs via a NO-driven planar shift of the iron in the enzyme's heme. Other proteins involved in NO biology are hame proteins where NO coordination plays an essential function so Hb can be regarded as a microcosm of NO biology. Invertebrates provide an opportunity to explore alternate functions or perhaps the original functions of Hbs. Modern oxygen carriers might have arisen as metalloproteins having the primary focus of NO metabolism rather than reversible oxygen binding. Newly discovered aspects of Hb function relate to the signaling and control processes that nitric oxide shows in biological systems. The comparative approach to these processes has played an important role in their elucidation.

The family of gonadotropin-releasing hormones (GnRHs) has been considered a vertebrate preserve until recently when new members were discovered in protochordates and GnRHlike immunoreactivity (GnRH-IR) was detected in neurons and extracts from molluscs. We provide evidence that such peptides exist and are biologically active in representatives of the lowest invertebrates in which neurons are identifiable. Two GnRH-like peptides were extracted by HPLC-RIA from the sea pansy R. koellikeri and found to mimic mammalian and chicken II GnRHs in causing an inhibition of peristaltic contractions, an activity which involves the circular musculature in the sea pansy. As GnRH-IR neurons were found to innervate the circular musculature of the body wall in the sea pansy and in the starlet anemone Nematostella vectensis, we suggest that GnRH-like peptides are involved in the modulation of peristalsis in these anthozoans. Supported by NSERC of Canada.

Symposia held to review cell volume regulation (CVR) after osmotic stress often distinguish between `invertebrate' and `vertebrate' topics. This implies differences in the way `invertebrate' cells go about their business. However, it is now obvious that CVR mechanisms are very similar from species to species, even from Kingdom to Kingdom. Implying differences in CVR mechanisms based on phylogeny is misleading. Generally, CVR in all cell types is accomplished by the regulation of two general categories of osmolytes: inorganic ions, usually [K.sup.+] and [CI.sup.-], and low molecular weight organic compounds, usually certain amino acids and quaternary ammonium compounds. The difference in who regulates what does not depend upon the presence or absence of a backbone, but instead upon the type of osmotic environment that a cell expects (in an evolutionary sense) to encounter. To illustrate this, we will compare the hypoosmotically induced mechanism of taurine efflux from RBC's of the bivalve, Noetia ponderosa, probably the best understood `invertebrate' cell type in this regard, and taurine efflux from a variety of `vertebrate' cells.

In free-spawning marine invertebrates, the egg represents the maternal energetic investment per offspring. Energetic content of eggs is positively correlated with egg size interspecifically. Therefore, egg size has been frequently used as an index of egg energetic content and is a central theme in marine invertebrate life history theory. The eggs of a number of invertebrate phyla are surrounded by extracellular structures. The best studied of these structures are the jelly coats of echinoderm eggs. These coats are composed of a network of polysaccharide fibers and glycoproteins. Jelly coats may constitute a substantial component of the energetic investment per offspring. Despite this, the energetic in jelly coats has never been reported. We measured the energetic content of Arbacia punctulata eggs with and without jelly coats. Jelly coats of unhydrated eggs comprised 1/3 of the combined egg and jelly coat volume. Mean energetic content of eggs with jelly coats was 0.0040 joules and 0.0032 joules without jelly coats. Thus, jelly coats comprise approximately 20o/S of the combined egg and jelly coat energy content. Comparative data with other echinoid species will be presented and the implications of these findings for marine invertebrate life history discussed.

A population of benthic, platyctene ctenophores previously recorded only from the Caribbean was studied in Spring 1994. V. multiformis occurred in dense patches (to 10,000 ind./m sq) on several species of algae on floating docks. Animals 2-20 mm diam deployed tentacles up to 60x the body length, forming a dense 'population filter' that appeared capable of exerting substantial predation pressure on plankton communities. In a 2.5-d experiment, a mean ingestion rate of 10 Artemia/ctenophore/h supported an individual growth rate of 27%/day, indicating that high feeding and growth rates are possible when prey are available. The size frequency distribution of ctenophores collected from algal substrates was strongly dominated by small individuals, possibly resulting from the tendency of this species to fragment and regenerate. Dramatic reductions in ctenophore populations corresponded to substantial reductions in salinity during heavy rains. Rapid recovery from such depletions was likely accomplished by fragmentation and asexual reproduction, although large animals also contained sexual embryos in late spring. I thank G.C. Fiedler and C. McGeorge for lab and field assistance.

Simple physical principles of engineering design of axial support in flexible cylindrical bodies will be used to frame a notion of possible sequences of evolutionary events leading from polyps and worms to arthropods, echinoderms, and vertebrates. Similarities in design of axes of bodies and appendages will be indicated. How pliant and rigid materials interact harmoniously in axial locomotion is a matter of structural design principles that differ at different size levels. Backbone-like structures in invertebrates will be interpreted in terms of their accompanying muscle structures. How these structures are made from fibrous materials will be a central issue.

Insulin was discovered in 1922 as the causative factor for a human metabolic disorder (diabetes mellitus), but it was recognized early that the hormone had a broad phylogenetic distribution. By the mid 1970s, primary structures of insulins from all classes of vertebrates had been obtained, including cyclostomes. More recently, the application of recombinant DNA techniques have identified insulin-like genes in invertebrates, including insects, molluscs and nematodes. These findings make it likely that insulin-like molecules are present in all metazoa. However, it is apparent that during evolution insulin has undergone changes in both structure and function. In particular, insulin acts primarily as a growth factor in invertebrates and a metabolic regulatory hormone in vertebrates. We will review here the structural features which have been conserved or changed in the vertebrate/invertebrate insulin genes and present a hypothesis on its functional evolution from a growth factor to a metabolic regulatory hormone.