Bryostatin enhancement of memory in Hermissenda

Lymnaea stagnalis as model for translational neuroscience research: From pond to bench

The purpose of this review is to illustrate how a reductionistic, but sophisticated, approach based on the use of a simple model system such as the pond snail Lymnaea stagnalis (L. stagnalis), might be useful to address fundamental questions in learning and memory. L. stagnalis, as a model, provides an interesting platform to investigate the dialog between the synapse and the nucleus and vice versa during memory and learning. More importantly, the "molecular actors" of the memory dialogue are well-conserved both across phylogenetic groups and learning paradigms, involving single- or multi-trials, aversion or reward, operant or classical conditioning. At the same time, this model could help to study how, where and when the memory dialog is impaired in stressful conditions and during aging and neurodegeneration in humans and thus offers new insights and targets in order to develop innovative therapies and technology for the treatment of a range of neurological and neurodegenerative disorders.

Bryostatin Effects on Cognitive Function and PKCɛ in Alzheimer's Disease Phase IIa and Expanded Access Trials

Bryostatin 1, a potent activator of protein kinase C epsilon (PKCɛ), has been shown to reverse synaptic loss and facilitate synaptic maturation in animal models of Alzheimer’s disease (AD), Fragile X, stroke, and other neurological disorders. In a single-dose (25 μg/m²) randomized double-blind Phase IIa clinical trial, bryostatin levels reached a maximum at 1-2 h after the start of infusion. In close parallel with peak blood levels of bryostatin, an increase of PBMC PKCɛ was measured (p = 0.0185) within 1 h from the onset of infusion. Of 9 patients with a clinical diagnosis of AD, of which 6 received drug and 3 received vehicle within a double-blind protocol, bryostatin increased the Mini-Mental State Examination (MMSE) score by +1.83±0.70 unit at 3 h versus –1.00±1.53 unit for placebo. Bryostatin was well tolerated in these AD patients and no drug-related adverse events were reported. The 25 μg/m² administered dose was based on prior clinical experience with three Expanded Access advanced AD patients treated with bryostatin, in which return of major functions such as swallowing, vocalization, and word recognition were noted. In one Expanded Access patient trial, elevated PKCɛ levels closely tracked cognitive benefits in the first 24 weeks as measured by MMSE and ADCS-ADL psychometrics. Pre-clinical mouse studies showed effective activation of PKCɛ and increased levels of BDNF and PSD-95. Together, these Phase IIa, Expanded Access, and pre-clinical results provide initial encouragement for bryostatin 1 as a potential treatment for AD.

Bryostatin and its synthetic analog, picolog rescue dermal fibroblasts from prolonged stress and contribute to survival and rejuvenation of human skin equivalents

Skin health is associated with the day-to-day activity of fibroblasts. The primary function of fibroblasts is to synthesize structural proteins, such as collagen, extracellular matrix proteins, and other proteins that support the structural integrity of the skin and are associated with younger, firmer, and more elastic skin that is better able to resist and recover from injury. At sub-nanomolar concentrations (0.03-0.3 nM), bryostatin-1 and its synthetic analog, picolog (0.1-10 nM) sustained the survival and activation of human dermal fibroblasts cultured under the stressful condition of prolonged serum deprivation. Bryostatin-1 treatment stabilized human skin equivalents (HSEs), a bioengineered combination of primary human skin cells (keratinocytes and dermal fibroblasts) on an extracellular matrix composed of mainly collagen. Fibroblasts activated by bryostatin-1 protected the structural integrity of HSEs. Bryostatin-1 and picolog prolonged activation of Erk in fibroblasts to promote cell survival. Chronic stress promotes the progression of apoptosis. Dermal fibroblasts constitutively express all components of Fas associated apoptosis, including caspase-8, an initiator enzyme of apoptosis. Prolong bryostatin-1 treatment reduced apoptosis by decreasing caspase-8 and protected dermal fibroblasts. Our data suggest that bryostatin-1 and picolog could be useful in anti-aging skincare, and could have applications in tissue engineering and regenerative medicine.

Securamine Derivatives from the Arctic Bryozoan Securiflustra securifrons

Bryozoans belonging to the Flustridae family have proven to be a rich source of structurally unique secondary metabolites. As part of our continuing search for bioactive secondary metabolites from Arctic marine invertebrates, the organic extract of Securiflustra securifrons was examined. This resulted in the isolation of three new halogenated, hexacyclic indole-imidazole alkaloids, securamines H-J (1-3), together with the previously reported compounds securamines C (4) and E (5). The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR and analysis of HRMS data. Through NMR and HRMS analysis, we were also able to prove that 1, 2, 4, and 5, when dissolved in MeOH, were converted into their corresponding artifacts, the securamine MeOH adducts m1, m2, m4, and m5. When redissolved in a non-nucleophilic solvent, the native variants were re-formed. We also found that 3 was a MeOH addition product of a native variant. Even though the structures of several securamines have been reported, their bioactivities were not examined. The securamines displayed various degrees of cytotoxicity against the human cancer cell lines A2058 (skin), HT-29 (colon), and MCF-7 (breast), as well as against nonmalignant human MRC-5 lung fibroblasts. Compounds 1, 2, and 5 were found to be active, with IC₅₀ values against the cancer cell lines ranging from 1.4 ± 0.1 to 10 ± 1 μM. The cytotoxicity of 1 was further evaluated and found to be time-dependent.

Conformation-activity relationships of polyketide natural products

Polyketides represent an important class of secondary metabolites that interact with biological targets connected to a variety of disease-associated pathways. Remarkably, nature's assembly lines, polyketide synthases, manufacture these privileged structures through a combinatorial mixture of just a few structural units. This review highlights the role of these structural elements in shaping a polyketide's conformational preferences, the use of computer-based molecular modeling and solution NMR studies in the identification of low-energy conformers, and the importance of conformational analogues in probing the bound conformation. In particular, this review covers several examples wherein conformational analysis complements classic structure-activity relationships in the design of biologically active natural product analogues.

Molecular regulation of synaptogenesis during associative learning and memory

Synaptogenesis plays a central role in associative learning and memory. The biochemical pathways that underlie synaptogenesis are complex and incompletely understood. Nevertheless, research has so far identified three conceptually distinct routes to synaptogenesis: cell-cell contact mediated by adhesion proteins, cell-cell biochemical signaling from astrocytes and other cells, and neuronal signaling through classical ion channels and cell surface receptors. The cell adhesion pathways provide the physical substrate to the new synaptic connection, while cell-cell signaling may provide a global or regional signal, and the activity-dependent pathways provide the neuronal specificity that is required for the new synapses to produce functional neuronal networks capable of storing associative memories. These three aspects of synaptogenesis require activation of a variety of interacting biochemical pathways that converge on the actin cytoskeleton and strengthen the synapse in an information-dependent manner. This article is part of a Special Issue titled SI: Brain and Memory.

Synthesis of a des-B-ring bryostatin analogue leads to an unexpected ring expansion of the bryolactone core

A convergent synthesis of a des-B-ring bryostatin analogue is described. This analogue was found to undergo an unexpected ring expansion of the bryolactone core to generate the corresponding 21-membered macrocycle. The parent analogue and the ring-expanded product both displayed nanomolar binding affinity for PKC. Despite containing A-ring substitution identical to that of bryostatin 1 and displaying bryostatin-like biological function, the des-B-ring analogues displayed a phorbol-like biological function in cells. These studies shed new light on the role of the bryostatin B-ring in conferring bryo-like biological function to bryostatin analogues.

PKC activators enhance GABAergic neurotransmission and paired-pulse facilitation in hippocampal CA1 pyramidal neurons

Bryostatin-1, a potent agonist of protein kinase C (PKC), has recently been found to enhance spatial learning and long-term memory in rats, mice, rabbits and the nudibranch Hermissenda, and to exert profound neuroprotective effects on Alzheimer's disease (AD) in transgenic mice. However, details of the mechanistic effects of bryostatin on learning and memory remain unclear. To address this issue, whole-cell recording, a dual-recording approach and extracellular recording techniques were performed on young (2-4months) Brown-Norway rats. We found that bath-applied bryostatin-1 significantly increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). The firing rate of GABAergic interneurons significantly was also increased as recorded with a loosely-attached extracellular recording configuration. Simultaneous recordings from communicating cell pairs of interneuron and pyramidal neuron revealed unique activity-dependent properties of GABAergic synapses. Furthermore, the bryostatin-induced increase of the frequency and amplitude of IPSCs was blocked by methionine enkephalin which selectively suppressed the excitability of interneurons. Pretreatment with RO-32-0432, a relatively specific PKCα antagonist, blocked the effect of bryostatin on sIPSCs. Finally, bryostatin increased paired-pulse ratio of GABAergic synapses that lasted for at least 20min while pretreatment with RO-32-0432 significantly reduced the ratio. In addition, 8-[2-(2-pentyl-cyclopropylmethl)-cyclopropyl]-octanoic acid (DCP-LA), a selective PKCε activator, also increased the frequency and amplitude of sIPSCs. Taken together, these results suggest that bryostatin enhances GABAergic neurotransmission in pyramidal neurons by activating the PKCα & ε-dependent pathway and by a presynaptic mechanism with excitation of GABAergic interneurons. These effects of bryostatin on GABAergic transmissions and modifiability may contribute to the improvement of learning and memory previously observed to be induced by bryostatin.

Protein kinase C mediates memory consolidation of taste avoidance conditioning in Lymnaea stagnalis

In Lymnaea stagnalis, in order to obtain a 10 min short-term memory (STM) of taste avoidance conditioning (TAC) at least 10 paired presentations of a conditioned stimulus (CS), sucrose, and an unconditioned stimulus (US), tactile stimulation to the animal's head, are required. Pre-exposure of snails to the protein kinase C (PKC) α and ε activator bryostatin (Bryo) facilitated STM formation in that only 5 paired CS-US trials were required. Typically 20 paired presentations of the CS-US are required for formation of STM and LTM. However, 20 paired presentations do not result in STM or LTM if snails are pre-incubated with a PKC inhibitor, Ro-32-0432. We also found that LTM lasting longer than 48 h was acquired with Bryo incubation for 45 min even after termination of the conditioning paradigm. These data suggest that activation of the α and ε isozymes of PKC is crucially involved in the formation of LTM and provide further support for a mechanism that has been conserved across the evolution of species ranging from invertebrate molluscs to higher mammals.

Marine natural products: bryostatins in preclinical and clinical studies

CONTEXT

Bryostatins represent an important group of pharmaceutically promising substances. These compounds are produced by commensal microorganisms naturally occurring in marine invertebrates, mainly in bryozoans. The most frequently investigated substance is bryostatin-1, which is a highly oxygenated macrolide with a polyacetate backbone.

OBJECTIVE

The aim of this work was to summarize documented preclinical and clinical effects of bryostatin-class compounds.

METHODS

A literature search was made of Medline and Web of Science databases in 2012.

RESULTS AND CONCLUSION

Our review showed that bryostatins are potent agonists of protein kinase C. In addition to this, their significant antineoplastic activity against several tumor types has also been established and described. Bryostatin's anticancer activity has been proved against various cancer types. Moreover, significant results have been achieved by using bryostatin-1 in combination with other therapies, including combination with vaccine testing. Concerning other important properties that bryostatins possess, their ability to sensitize some resistant cells to chemotherapy agents, or immunoactivity and further stimulating growth of new neural connections, and enhancing effect on long-term memory are worth mentioning. In particular, some new bryostatin analogs could represent potential therapeutic agent for the treatment of cancer and other diseases in future.

Adduct formation in liquid chromatography-triple quadrupole mass spectrometric measurement of bryostatin 1

Bryostatin 1, a potential anti-Alzheimer drug, is effective at subnanomolar concentrations. Measurement is complicated by the formation of low m/z degradation products and the formation of adducts with various cations, which make accurate quantitation difficult. Adduct formation caused the sample matrix or mobile phase to partition bryostatin 1 into products of different mass. Degradation of the 927 [M+Na](+) ion to a 869m/z product was strongly influenced by ionization conditions. We validated a bryostatin 1 assay in biological tissues using capillary column HPLC with nanospray ionization (NSI) in a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode. Adduct formation was controlled by adding 1mM acetic acid and 0.1mM sodium acetate to the HPLC buffer, maximizing the formation of the [M+Na](+) ion. Efficient removal of contaminating cholesterol from the sample during solvent extraction was also critical. The increased sensitivity provided by NSI and capillary-bore columns and the elimination of signal partitioning due to adduct formation and degradation in the ionization source enabled a detection limit of 1×10(-18)mol of bryostatin 1 and a LLOQ of 3×10(-18)mol from 1μl of sample. Bryostatin 1 at low pmol/l concentrations enabled measurement in brain and other tissues without the use of radioactive labels. Despite bryostatin 1's high molecular weight, considerable brain access was observed, with peak brain concentrations exceeding 8% of the peak blood plasma concentrations. Bryostatin 1 readily crosses the blood-brain barrier, reaching peak concentrations of 0.2nM, and specifically activates and translocates brain PKCɛ.

Critical period of memory enhancement during taste avoidance conditioning in Lymnaea stagnalis

The present study investigated the optimal training procedure leading to long-lasting taste avoidance behavior in Lymnaea. A training procedure comprising 5 repeated pairings of a conditional stimulus (CS, sucrose), with an unconditional stimulus (US, a tactile stimulation to the animal's head), over a 4-day period resulted in an enhanced memory formation than 10 CS-US repeated pairings over a 2-day period or 20 CS-US repeated pairings on a single day. Backward conditioning (US-CS) pairings did not result in conditioning. Thus, this taste avoidance conditioning was CS-US pairing specific. Food avoidance behavior was not observed following training, however, if snails were immediately subjected to a cold-block (4°C for 10 min). It was critical that the cold-block be applied within 10 min to block long-term memory (LTM) formation. Further, exposure to the cold-block 180 min after training also blocked both STM and LTM formation. The effects of the cold-block on subsequent learning and memory formation were also examined. We found no long lasting effects of the cold-block on subsequent memory formation. If protein kinase C was activated before the conditioning paradigm, snails could still acquire STM despite exposure to the cold-block.

Lead Diversification through a Prins-Driven Macrocyclization Strategy: Application to C13-Diversified Bryostatin Analogues

The design, synthesis, and biological evaluation of a novel class of C13-diversified bryostatin analogues are described. An innovative and general strategy based on a Prins macrocyclization-nucleophilic trapping cascade was used to achieve late-stage diversification. In vitro analysis of selected library members revealed that modification at the C13 position of the bryostatin scaffold can be used as a diversification handle to regulate biological activity.

Biological profile of the less lipophilic and synthetically more accessible bryostatin 7 closely resembles that of bryostatin 1

The bryostatins are a group of 20 macrolides isolated by Pettit and co-workers from the marine organism Bugula neritina. Bryostatin 1, the flagship member of the family, has been the subject of intense chemical and biological investigations due to its remarkably diverse biological activities, including promising indications as therapy for cancer, Alzheimer's disease, and HIV. Other bryostatins, however, have attracted far less attention, most probably due to their relatively low natural abundance and associated scarcity of supply. Among all macrolides in this family, bryostatin 7 is biologically the most potent protein kinase C (PKC) ligand (in terms of binding affinity) and also the first bryostatin to be synthesized in the laboratory. Nonetheless, almost no biological studies have been carried out on this agent. We describe herein the total synthesis of bryostatin 7 based on our pyran annulation technology, which allows for the first detailed biological characterizations of bryostatin 7 with side-by-side comparisons to bryostatin 1. The results suggest that the more easily synthesized and less lipophilic bryostatin 7 may be an effective surrogate for bryostatin 1.

Medicinal benefits of marine invertebrates: sources for discovering natural drug candidates

Marine invertebrates are one of the major groups of organisms, which could be diversified under the major taxonomic groups of Porifera, Cnidaria, Mollusca, Arthropoda, Echinodermata, and many other minor phyla. To date, range of medicinal benefits and a significant number of marine natural products (MNPs) have been discovered from marine invertebrates. Seafood diet from edible marine invertebrates such as mollusks and crustaceans has been linked with various medicinal benefits to improve human health. Among marine invertebrates, spongers from phylum Porifera is the most dominant group responsible for discovering large number of MNPs, which have been used as template to develop therapeutic drugs. MNPs isolated from invertebrates have shown wide range of therapeutic properties including antimicrobial, antioxidant, antihypertensive, anticoagulant, anticancer, anti-inflammatory, wound healing and immune modulator, and other medicinal effects. Therefore, marine invertebrates are rich sources of chemical diversity and health benefits for developing drug candidates, cosmetics, nutritional supplements, and molecular probes that can be supported to increase the healthy life span of human.

Activation of protein kinase C isozymes for the treatment of dementias

Memories are much more easily impaired than improved. Dementias, a lasting impairment of memory function, occur in a variety of cognitive disorders and become more clinically dominant as the population ages. Protein kinase C is one of the "cognitive kinases," and plays an essential role in both memory acquisition and maintenance. Deficits in protein kinase C (PKC) signal cascades in neurons represent one of the earliest changes in the brains of patients with Alzheimer's disease (AD) and other types of memory impairment, including those related to cerebral ischemia and ischemic stroke. Inhibition or impairment of PKC activity results in compromised learning and memory, whereas an appropriate activation of certain PKC isozymes leads to an enhancement of learning and memory and/or antidementic effects. In preclinical studies, PKC activators have been shown to increase the expression and activity of PKC isozymes, thereby restoring PKC signaling and downstream activity, including stimulation of neurotrophic activity, synaptic/structural remodeling, and synaptogenesis in the hippocampus and related cortical areas. PKC activators also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation and support anti-apoptotic processes in the brain. These observations strongly suggest that PKC pharmacology may represent an attractive area for the development of effective cognition-enhancing therapeutics for the treatment of dementias.

FEATURES

Natural Products in the Drug Discovery Programmes in Alzheimer's: Impacts and Prospects.

Advancement of chitosan based nanoparticles for present and future interests.

Algal Tranformations for Enhanced Metabolite Production and Pathway Manipulation.

Design, synthesis, and evaluation of potent bryostatin analogs that modulate PKC translocation selectivity

Modern methods for the identification of therapeutic leads include chemical or virtual screening of compound libraries. Nature's library represents a vast and diverse source of leads, often exhibiting exquisite biological activities. However, the advancement of natural product leads into the clinic is often impeded by their scarcity, complexity, and nonoptimal properties or efficacy as well as the challenges associated with their synthesis or modification. Function-oriented synthesis represents a strategy to address these issues through the design of simpler and therefore synthetically more accessible analogs that incorporate the activity-determining features of the natural product leads. This study illustrates the application of this strategy to the design and synthesis of functional analogs of the bryostatin marine natural products. It is specifically directed at exploring the activity-determining role of bryostatin A-ring functionality on PKC affinity and selectivity. The resultant functional analogs, which were prepared by a flexible, modular synthetic strategy, exhibit excellent affinity to PKC and differential isoform selectivity. These and related studies provide the basic information needed for the design of simplified and thus synthetically more accessible functional analogs that target PKC isoforms, major targets of therapeutic interest.

PKC activator therapeutic for mild traumatic brain injury in mice

Traumatic brain injury (TBI) is a frequent consequence of vehicle, sport and war related injuries. More than 90% of TBI patients suffer mild injury (mTBI). However, the pathologies underlying the disease are poorly understood and treatment modalities are limited. We report here that in mice, the potent PKC activator bryostatin1 protects against mTBI induced learning and memory deficits and reduction in pre-synaptic synaptophysin and post-synaptic spinophylin immunostaining. An effective treatment has to start within the first 8h after injury, and includes 5 × i.p. injections over a period of 14 days. The treatment is dose dependent. Exploring the effects of the repeated bryostatin1 treatment on the processing of the amyloid precursor protein, we found that the treatment induced an increase in the putative α-secretase ADAM10 and a reduction in β-secretase activities. Both these effects could contribute towards a reduction in β-amyloid production. These results suggest that bryostatin1 protects against mTBI cognitive and synaptic sequela by rescuing synapses, which is possibly mediated by an increase in ADAM10 and a decrease in BACE1 activity. Since bryostatin1 has already been extensively used in clinical trials as an anti-cancer drug, its potential as a remedy for the short- and long-term TBI sequelae is quite promising.

The participation of NMDA receptors, PKC, and MAPK in the formation of memory following operant conditioning in Lymnaea

Background

Memory is the ability to store, retain, and later retrieve information that has been learned. Intermediate term memory (ITM) that persists for up to 3 h requires new protein synthesis. Long term memory (LTM) that persists for at least 24 h requires: DNA transcription, RNA translation, and the trafficking of newly synthesized proteins. It has been shown in a number of different model systems that NMDA receptors, protein kinase C (PKC) and mitogen activated protein kinase (MAPK) are all involved in the memory formation process.

Results

Here we show that snails trained in control conditions are capable of forming, depending on the training procedure used, either ITM or LTM. However, blockage of NMDA receptors (MK 801), inhibition of PKC (GF109203X hydrochloride) and MAPK activity (UO126) prevent the formation of both ITM and LTM.

Conclusions

The injection of either U0126 or GF109203X, which inhibit MAPK and PKC activity respectively, 1 hour prior to training results in the inhibition of both ITM and LTM formation. We further found that NMDA receptor activity was necessary in order for both ITM and LTM formation.

New approaches to the total synthesis of the bryostatin antitumor macrolides

In this Focus Review, we give an overview of various bryostatin total syntheses. We also discuss the synthesis of various bryostatin analogues and their biological activity. Work reviewed includes that of Masamune, Evans, Nishiyama and Yamamura, Hale and Manaviazar, Trost, Wender, Keck, Burke, Thomas, and Krische. Our coverage is primarily for the period 2001-2009, since detailed reviews already exist on bryostatin total synthesis work and biology up to this time.

Reduction of beta-amyloid levels by novel protein kinase C(epsilon) activators

Isoform-specific protein kinase C (PKC) activators may be useful as therapeutic agents for the treatment of Alzheimer disease. Three new epsilon-specific PKC activators, made by cyclopropanation of polyunsaturated fatty acids, have been developed. These activators, AA-CP4, EPA-CP5, and DHA-CP6, activate PKCepsilon in a dose-dependent manner. Unlike PKC activators that bind to the 1,2-diacylglycerol-binding site, such as bryostatin and phorbol esters, which produce prolonged down-regulation, the new activators produced sustained activation of PKC. When applied to cells expressing human APPSwe/PS1delta, which produce large quantities of beta-amyloid peptide (Abeta), DCP-LA and DHA-CP6 reduced the intracellular and secreted levels of Abeta by 60-70%. In contrast to the marked activation of alpha-secretase produced by PKC activators in fibroblasts, the PKC activators produced only a moderate and transient activation of alpha-secretase in neuronal cells. However, they activated endothelin-converting enzyme to 180% of control levels, suggesting that the Abeta-lowering ability of these PKCepsilon activators is caused by increasing the rate of Abeta degradation by endothelin-converting enzyme and not by activating nonamyloidogenic amyloid precursor protein metabolism.

Neuroprotective versus tumorigenic protein kinase C activators

Protein kinase C (PKC) activators possess potent neurotrophic and neuroprotective activity, thus indicating potential applications in treating neurodegenerative diseases, stroke and traumatic brain injury. Although some activators, such as bryostatin and gnidimacrin, have been tested as antitumor agents, others, such as phorbol esters, are potent tumor promoters. All PKC activators downregulate PKC at high concentrations and long application times. However, tumorigenic activators downregulate certain PKC isozymes, especially PKCdelta, more strongly. Tumorigenic activators possess unique structural features that could account for this difference. At concentrations that minimize PKC downregulation, PKC activators can improve long-term memory, reduce beta-amyloid levels, induce synaptogenesis, promote neuronal repair and inhibit cell proliferation. Intermittent, low concentrations of structurally specific, non-tumorigenic PKC activators, therefore, could offer therapeutic benefit for a variety of neurologic disorders.

Chemical defenses: from compounds to communities

Marine natural products play critical roles in the chemical defense of many marine organisms and in some cases can influence the community structure of entire ecosystems. Although many marine natural products have been studied for biomedical activity, yielding important information about their biochemical effects and mechanisms of action, much less is known about ecological functions. The way in which marine consumers perceive chemical defenses can influence their health and survival and determine whether some natural products persist through a food chain. This article focuses on selected marine natural products, including okadaic acid, brevetoxins, lyngbyatoxin A, caulerpenyne, bryostatins, and isocyano terpenes, and examines their biosynthesis (sometimes by symbiotic microorganisms), mechanisms of action, and biological and ecological activity. We selected these compounds because their impacts on marine organisms and communities are some of the best-studied among marine natural products. We discuss the effects of these compounds on consumer behavior and physiology, with an emphasis on neuroecology. In addition to mediating a variety of trophic interactions, these compounds may be responsible for community-scale ecological impacts of chemically defended organisms, such as shifts in benthic and pelagic community composition. Our examples include harmful algal blooms; the invasion of the Mediterranean by Caulerpa taxifolia; overgrowth of coral reefs by chemically rich macroalgae and cyanobacteria; and invertebrate chemical defenses, including the role of microbial symbionts in compound production.

Localization of 'Candidatus Endobugula sertula' and the bryostatins throughout the life cycle of the bryozoan Bugula neritina

'Candidatus Endobugula sertula,' the uncultivated gamma-proteobacterial symbiont of the marine bryozoan Bugula neritina, synthesizes bryostatins, complex polyketides that render B. neritina larvae unpalatable to predators. Although the symbiosis is well described, little is known about the locations of 'E. sertula' or the bryostatins throughout larval settlement, metamorphosis and early development. In this study, we simultaneously localized 'E. sertula' and the bryostatins in multiple stages of the B. neritina life cycle, using a novel bryostatin detection method based on its known ability to bind mammalian protein kinase C. Our results suggest that the bryostatins are deposited onto the exterior of B. neritina larvae during embryonic development, persist on the larval surface throughout metamorphosis and are shed prior to cuticle formation. During metamorphosis, 'E. sertula' remains adhered to the larval pallial epithelium and is incorporated into the preancestrula cystid tissue layer, which ultimately develops into a bud and gives rise to the next zooid in the colony. Colocalization of bryostatin signal with aggregates of 'E. sertula' in buds of ancestrulae suggested new synthesis of bryostatins in ancestrulae. In adult B. neritina colonies, symbiont microcolonies were observed in the funicular cords of rhizoids, which likely result in asexual transmission of 'E. sertula' to regenerated colonies. Furthermore, bryostatin signal was detected on the surface of the rhizoids of adult B. neritina colonies. Through simultaneous localization of the bryostatins and the 'E. sertula,' we determined how 'E. sertula' is transmitted, and identified shifts in bryostatin localization throughout the life cycle of the host B. neritina.