The Experts below are selected from a list of 1512 Experts worldwide ranked by ideXlab platform
Peiyuan Qian - One of the best experts on this subject based on the ideXlab platform.
-
exploring the regulatory role of nitric oxide no and the no p38mapk cgmp pathway in larval settlement of the bryozoan bugula Neritina
Biofouling, 2018Co-Authors: Xiao-xue Yang, Yu Zhang, Yue Him Wong, Gen Zhang, Peiyuan QianAbstract:The bryozoan Bugula Neritina is a cosmopolitan marine fouling species that causes major fouling problems in sub-tropical waters. Settlement of B. Neritina larvae can be triggered without an obvious external cue. Here, the negative regulatory role of nitric oxide (NO) during larval settlement of B. Neritina was demonstrated to be mediated by cyclic guanosine monophosphate (cGMP). Although the regulatory role of the NO-p38 MAPK signaling axis in larval settlement was not evident, inhibition of nitric oxide synthase (NOS) led to the deactivation of p38 MAPK. Exclusive localization of NO and NO signaling components in sensory-related organs of the larvae is consistent with its signal transduction function in metamorphosis. Overall, this study provides new insights into the regulatory roles of the NO-p38MAPK/cGMP pathway in B. Neritina settlement.
-
Exploring the regulatory role of nitric oxide (NO) and the NO-p38MAPK/cGMP pathway in larval settlement of the bryozoan Bugula Neritina
Biofouling, 2018Co-Authors: Xiao-xue Yang, Yu Zhang, Yue Him Wong, Zhang, Peiyuan QianAbstract:The bryozoan Bugula Neritina is a cosmopolitan marine fouling species that causes major fouling problems in sub-tropical waters. Settlement of B. Neritina larvae can be triggered without an obvious external cue. Here, the negative regulatory role of nitric oxide (NO) during larval settlement of B. Neritina was demonstrated to be mediated by cyclic guanosine monophosphate (cGMP). Although the regulatory role of the NO-p38 MAPK signaling axis in larval settlement was not evident, inhibition of nitric oxide synthase (NOS) led to the deactivation of p38 MAPK. Exclusive localization of NO and NO signaling components in sensory-related organs of the larvae is consistent with its signal transduction function in metamorphosis. Overall, this study provides new insights into the regulatory roles of the NO-p38MAPK/cGMP pathway in B. Neritina settlement.
-
A novel assessment of the traction forces upon settlement of two typical marine fouling invertebrates using PDMS micropost arrays
The Company of Biologists, 2018Co-Authors: Kang Xiao, Peiyuan Qian, Xiao-xue Yang, Wen-bin Cao, Cu-huang Rong, Lian-guo Chen, Wei-jia Wen, Yu ZhangAbstract:Marine biofouling poses a severe threat to maritime and aquaculture industries. To prevent the attachment of marine biofouling organisms on man-made structures, countless cost and effort was spent annually. In particular, most attention has been paid on the development of efficient and environmentally friendly fouling-resistant coatings, as well as larval settlement mechanism of several major biofouling invertebrates. In this study, polydimethylsiloxane (PDMS) micropost arrays were utilized as the settlement substrata and opposite tractions were identified during early settlement of the barnacle Amphibalanus amphitrite and the bryozoan Bugula Neritina. The settling A. amphitrite pushed the periphery microposts with an average traction force of 376.2 nN, while settling B. Neritina pulled the periphery microposts with an average traction force of 205.9 nN. These micropost displacements are consistent with the body expansion of A. amphitrite during early post-settlement metamorphosis stage and elevation of wall epithelium of B. Neritina during early pre-ancestrula stage, respectively. As such, the usage of micropost array may supplement the traditional histological approach to indicate the early settlement stages or even the initiation of larval settlement of marine fouling organisms, and could finally aid in the development of automatic monitoring platform for the real-time analysis on this complex biological process
-
in silico prediction of neuropeptides peptide hormone transcripts in the cheilostome bryozoan bugula Neritina
PLOS ONE, 2016Co-Authors: Yue Him Wong, Peiyuan Qian, Gen ZhangAbstract:The bryozoan Bugula Neritina has a biphasic life cycle that consists of a planktonic larval stage and a sessile juvenile/adult stage. The transition between these two stages is crucial for the development and recruitment of B. Neritina. Metamorphosis in B. Neritina is mediated by both the nervous system and the release of developmental signals. However, no research has been conducted to investigate the expression of neuropeptides (NP)/peptide hormones in B. Neritina larvae. Here, we report a comprehensive study of the NP/peptide hormones in the marine bryozoan B. Neritina based on in silico identification methods. We recovered 22 transcripts encompassing 11 NP/peptide hormone precursor transcript sequences. The transcript sequences of the 11 isolated NP precursors were validated by cDNA cloning using gene-specific primers. We also examined the expression of three peptide hormone precursor transcripts (BnFDSIG, BnILP1, BnGPB) in the coronate larvae of B. Neritina, demonstrating their distinct expression patterns in the larvae. Overall, our findings serve as an important foundation for subsequent investigations of the peptidergic control of bryozoan larval behavior and settlement.
-
In Silico Prediction of Neuropeptides/Peptide Hormone Transcripts in the Cheilostome Bryozoan Bugula Neritina
PloS one, 2016Co-Authors: Yue Him Wong, Zhang, Peiyuan QianAbstract:The bryozoan Bugula Neritina has a biphasic life cycle that consists of a planktonic larval stage and a sessile juvenile/adult stage. The transition between these two stages is crucial for the development and recruitment of B. Neritina. Metamorphosis in B. Neritina is mediated by both the nervous system and the release of developmental signals. However, no research has been conducted to investigate the expression of neuropeptides (NP)/peptide hormones in B. Neritina larvae. Here, we report a comprehensive study of the NP/peptide hormones in the marine bryozoan B. Neritina based on in silico identification methods. We recovered 22 transcripts encompassing 11 NP/peptide hormone precursor transcript sequences. The transcript sequences of the 11 isolated NP precursors were validated by cDNA cloning using gene-specific primers. We also examined the expression of three peptide hormone precursor transcripts (BnFDSIG, BnILP1, BnGPB) in the coronate larvae of B. Neritina, demonstrating their distinct expression patterns in the larvae. Overall, our findings serve as an important foundation for subsequent investigations of the peptidergic control of bryozoan larval behavior and settlement.
Nicole B. Lopanik - One of the best experts on this subject based on the ideXlab platform.
-
influence of symbiont produced bioactive natural products on holobiont fitness in the marine bryozoan bugula Neritina via protein kinase c pkc
Marine Biology, 2016Co-Authors: Meril Mathew, Nicole B. Lopanik, Kayla I Bean, Yvette Tematetiagueu, Adrian Caciula, Ion I Mandoiu, Alexander ZelikovskyAbstract:Marine invertebrates are a major source of bioactive natural products, many of which are produced by associated microbes. These compounds protect the invertebrate host against predators, competitors, or pathogens by affecting the cellular processes of the host’s adversary, but knowledge about the interaction of the host itself with these symbiont-produced natural products is limited. For example, larvae of the marine bryozoan, Bugula Neritina, are defended from predation by the bryostatins, polyketides synthesized by its uncultured endosymbiont, “Candidatus Endobugula sertula.” Bryostatins are potent modulators of the eukaryotic signaling protein, protein kinase C (PKC) that is involved in many cellular processes. In this study, we investigated how host reproduction responds to the absence of the symbiont and symbiont-produced bryostatins in colonies after antibiotic curing and in colonies with naturally reduced symbiont titers. The fecundity of the symbiont-reduced B. Neritina colonies was significantly decreased, suggesting that host reproduction is dependent on the symbiont, and/or the bryostatins they produce. To assess the role of PKC in this response, Western blot analysis of protein extracts from symbiotic and symbiont-reduced B. Neritina colonies revealed a difference in bryostatin-activated conventional PKCs, but none for bryostatin-independent PKCs. Similar results were observed for PKCs in symbiotic and naturally occurring symbiont-reduced colonies, as well as in the model invertebrate, Caenorhabditis elegans, exposed to bryostatin, suggesting that the bryostatins potentially modulate PKC activity in symbiotic B. Neritina and bryostatin-exposed C. elegans. Analysis of the B. Neritina transcriptome led to the identification of five PKC isozymes. Since PKCs have been reported to be involved in regulation of reproductive processes and oocyte maturation in various organisms, the findings of this study suggest that the symbiont-produced bryostatins are an important cue for reproduction in the host B. Neritina via PKC activation.
-
latitudinal variation of a defensive symbiosis in the bugula Neritina bryozoa sibling species complex
PLOS ONE, 2014Co-Authors: Jonathan Linneman, Grace Limfong, Darcy Paulus, Nicole B. LopanikAbstract:Mutualistic relationships are beneficial for both partners and are often studied within a single environment. However, when the range of the partners is large, geographical differences in selective pressure may shift the relationship outcome from positive to negative. The marine bryozoan Bugula Neritina is a colonial invertebrate common in temperate waters worldwide. It is the source of bioactive polyketide metabolites, the bryostatins. Evidence suggests that an uncultured vertically transmitted symbiont, “Candidatus Endobugula sertula”, hosted by B. Neritina produces the bryostatins, which protect the vulnerable larvae from predation. Studies of B. Neritina along the North American Atlantic coast revealed a complex of two morphologically similar sibling species separated by an apparent biogeographic barrier: the Type S sibling species was found below Cape Hatteras, North Carolina, while Type N was found above. Interestingly, the Type N colonies lack “Ca. Endobugula sertula” and, subsequently, defensive bryostatins; their documented northern distribution was consistent with traditional biogeographical paradigms of latitudinal variation in predation pressure. Upon further sampling of B. Neritina populations, we found that both host types occur in wider distribution, with Type N colonies living south of Cape Hatteras, and Type S to the north. Distribution of the symbiont, however, was not restricted to Type S hosts. Genetic and microscopic evidence demonstrates the presence of the symbiont in some Type N colonies, and larvae from these colonies are endowed with defensive bryostatins and contain “Ca. Endobugula sertula”. Molecular analysis of the symbiont from Type N colonies suggests an evolutionarily recent acquisition, which is remarkable for a symbiont thought to be transmitted only vertically. Furthermore, most Type S colonies found at higher latitudes lack the symbiont, suggesting that this host-symbiont relationship is more flexible than previously thought. Our data suggest that the symbiont, but not the host, is restricted by biogeographical boundaries.
-
ontogeny of a symbiont produced chemical defense in bugula Neritina bryozoa
Marine Ecology Progress Series, 2006Co-Authors: Nicole B. Lopanik, Nancy M Targett, Niels LindquistAbstract:The larvae of the arborescent bryozoan Bugula Neritina are chemically defended against predators by unpalatable secondary metabolites called bryostatins. Bryostatins, polyketide- derived secondary compounds, are produced by the bacterial symbiont 'Candidatus Endobugula sertula', which is present throughout all life stages of B. Neritina. Crude extracts of larval and all juve- nile stages of B. Neritina significantly reduced pinfish feeding (p < 0.003). Extract unpalatability is due to high bryostatin concentrations. As B. Neritina increases in age after larval settlement and metamor- phosis, palatability increases as bryostatin concentrations decrease precipitously. Extracts of brood- ing portions of adult colonies reduced pinfish feeding by a significant 54% (p = 0.008), whereas ex- tracts of non-brooding portions of the same colonies resulted in a non-significant 20% decline in feeding (p = 0.125). Our data suggest that the different life stages of B. Neritina employ alternate de- fensive strategies. The mobile, short-lived larvae and early-stage juveniles are defended from preda- tors by having deterrent levels of bryostatins; in contrast, the older juveniles and adults, which are clonal and relatively long-lived, may be defended largely by high levels of structural material (i.e. chitin and carbonate). Predation pressure on the vulnerable larval stage of B. Neritina appears in part to have driven selection for the development and maintenance of the symbiotic relationship between B. Neritina and Ca. Endobugula sertula whereby the larvae are chemically defended by symbiont- produced bryostatins.
-
isolation of two polyketide synthase gene fragments from the uncultured microbial symbiont of the marine bryozoan bugula Neritina
Applied and Environmental Microbiology, 2006Co-Authors: Nicole B. Lopanik, Nancy M Targett, Niels LindquistAbstract:"Candidatus Endobugula sertula," the uncultured microbial symbiont of the bryozoan Bugula Neritina, produces ecologically and biomedically important polyketide metabolites called bryostatins. We isolated two gene fragments from B. Neritina larvae that have high levels of similarity to polyketide synthase genes. These gene fragments are clearly associated with the symbiont and not with the host.
-
Structure of bryostatin 20: A symbiont-produced chemical defense for larvae of the host bryozoan, Bugula Neritina
Journal of Natural Products, 2004Co-Authors: Nicole B. Lopanik, Kirk R. Gustafson, Niels LindquistAbstract:Larvae of the marine bryozoan Bugula Neritina are defended against potential predators by high concentrations of bryostatins, which are produced by a bacterial symbiont of the bryozoan. From the larvae of B. Neritina, three bryostatins, bryostatin 10 (1), the novel bryostatin 20 (2), and an as yet uncharacterized bryostatin, were isolated that were unpalatable to fish. These deterrent bryostatins represent the first example from the marine environment of a microbial symbiont producing an antipredator defense for its host. The structure of bryostatin 20 (2) was determined by spectral comparison with previously described bryostatins.
Margo G. Haygood - One of the best experts on this subject based on the ideXlab platform.
-
localization of candidatus endobugula sertula and the bryostatins throughout the life cycle of the bryozoan bugula Neritina
The ISME Journal, 2007Co-Authors: Seana K Davidson, Koty H. Sharp, Margo G. HaygoodAbstract:‘Candidatus Endobugula sertula,’ the uncultivated γ-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.
-
candidatus endobugula glebosa a specific bacterial symbiont of the marine bryozoan bugula simplex
Applied and Environmental Microbiology, 2004Co-Authors: Grace E Lim, Margo G. HaygoodAbstract:The bryozoans Bugula Neritina and Bugula simplex harbor bacteria in the pallial sinuses of their larvae as seen by electron microscopy. In B. Neritina, the bacterial symbiont has been characterized as a gamma-proteobacterium, “Candidatus Endobugula sertula.” “Candidatus E. sertula” has been implicated as the source of the bryostatins, polyketides that provide chemical defense to the host and are also being tested for use in human cancer treatments. In this study, the bacterial symbiont in B. simplex larvae was identified by 16S rRNA-targeted PCR and sequencing as a gamma-proteobacterium closely related to and forming a monophyletic group with “Candidatus E. sertula.” In a fluorescence in situ hybridization, a 16S ribosomal DNA probe specific to the B. simplex symbiont hybridized to long rod-shaped bacteria in the pallial sinus of a B. simplex larva. The taxonomic status “Candidatus Endobugula glebosa” is proposed for the B. simplex larval symbiont. Degenerate polyketide synthase (PKS) primers amplified a gene fragment from B. simplex that closely matched a PKS gene fragment from the bryostatin PKS cluster. PCR surveys show that the symbiont and this PKS gene fragment are consistently and uniquely associated with B. simplex. Bryostatin activity assays and chemical analyses of B. simplex extracts reveal the presence of compounds similar to bryostatins. Taken together, these findings demonstrate a symbiosis in B. simplex that is similar and evolutionarily related to that in B. Neritina.
-
evidence for the biosynthesis of bryostatins by the bacterial symbiont candidatus endobugula sertula of the bryozoan bugula Neritina
Applied and Environmental Microbiology, 2001Co-Authors: Seana K Davidson, Scott W Allen, Christine Anderson, Margo G. HaygoodAbstract:The marine bryozoan, Bugula Neritina, is the source of the bryostatins, a family of macrocyclic lactones with anticancer activity. Bryostatins have long been suspected to be bacterial products. B. Neritina harbors the uncultivated gamma proteobacterial symbiont “Candidatus Endobugula sertula.” In this work several lines of evidence are presented that show that the symbiont is the most likely source of bryostatins. Bryostatins are complex polyketides similar to bacterial secondary metabolites synthesized by modular type I polyketide synthases (PKS-I). PKS-I gene fragments were cloned from DNA extracted from the B. Neritina-“E. sertula” association, and then primers specific to one of these clones, KSa, were shown to amplify the KSa gene specifically and universally from total B. Neritina DNA. In addition, a KSa RNA probe was shown to bind specifically to the symbiotic bacteria located in the pallial sinus of the larvae of B. Neritina and not to B. Neritina cells or to other bacteria. Finally, B. Neritina colonies grown in the laboratory were treated with antibiotics to reduce the numbers of bacterial symbionts. Decreased symbiont levels resulted in the reduction of the KSa signal as well as the bryostatin content. These data provide evidence that the symbiont E. sertula has the genetic potential to make bryostatins and is necessary in full complement for the host bryozoan to produce normal levels of bryostatins. This study demonstrates that it may be possible to clone bryostatin genes from B. Neritina directly and use these to produce bryostatins in heterologous host bacteria.
-
identification of sibling species of the bryozoan bugula Neritina that produce different anticancer bryostatins and harbor distinct strains of the bacterial symbiont candidatus endobugula sertula
The Biological Bulletin, 1999Co-Authors: Seana K Davidson, Margo G. HaygoodAbstract:Although the cosmopolitan marine bryozoan Buga chemotype M lacks bryostatins with the octa-2,4- dienoate substituent. B. Neritina contains a symbiotic y-pro- teobacterium "Cundidutus Endobugula sertula," and it has been proposed that bryostatins may be synthesized by bac- terial symbionts. In this study, B. Neritina populations along the California coast were sampled for genetic variation and bryostatin content. Colonies that differ in chemotype also differ genetically by 8% in the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene; this difference is sufficient to suggest that the chemotypes represent different species. Each species contains a distinct strain of "E. sertula" that differs at four nucleotide sites in the small subunit ribo- somal RNA (SSU rRNA) gene. These results indicate that the chemotypes have a genetic basis rather than an environ- mental cause. Gene sequences from an Atlantic sample matched sequences from the California chemotype M col- onies, suggesting that this type may be cosmopolitan due to transport on boat hulls.
-
identification of sibling species of the bryozoan bugula Neritina that produce different anticancer bryostatins and harbor distinct strains of the bacterial symbiont candidatus endobugula sertula
The Biological Bulletin, 1999Co-Authors: Seana K Davidson, Margo G. HaygoodAbstract:Although the cosmopolitan marine bryozoan Bugula Neritina is recognized as a single species, natural products from this bryozoan vary among populations. B. Neritina is the source of the anticancer drug candidate bryostatin 1, but it also produces other bryostatins, and different populations contain different bryostatins. We defined two chemotypes on the basis of previous studies: chemotype O contains bryostatins with an octa-2,4-dienoate substituent (including bryostatin 1), as well as other bryostatins; chemotype M lacks bryostatins with the octa-2,4-dienoate substituent. B. Neritina contains a symbiotic gamma-proteobacterium "Candidatus Endobugula sertula," and it has been proposed that bryostatins may be synthesized by bacterial symbionts. In this study, B. Neritina populations along the California coast were sampled for genetic variation and bryostatin content. Colonies that differ in chemotype also differ genetically by 8% in the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene; this difference is sufficient to suggest that the chemotypes represent different species. Each species contains a distinct strain of "E. sertula" that differs at four nucleotide sites in the small subunit ribosomal RNA (SSU rRNA) gene. These results indicate that the chemotypes have a genetic basis rather than an environmental cause. Gene sequences from an Atlantic sample matched sequences from the California chemotype M colonies, suggesting that this type may be cosmopolitan due to transport on boat hulls.
Yue Him Wong - One of the best experts on this subject based on the ideXlab platform.
-
transcriptomic analysis of the mode of action of the candidate anti fouling compound di 1h indol 3 yl methane dim on a marine biofouling species the bryozoan bugula Neritina
Marine Pollution Bulletin, 2020Co-Authors: Lu Zhang, Yu Zhang, Kailing Wang, Yue Him WongAbstract:Abstract Di(1H-indol-3-yl)methane (DIM) was previously suggested to be an environmentally friendly antifouling compound, but it was also reported that the compound was highly stable in natural seawater. The present study reported that 3 h DIM treatments at 4 μg mL−1 or higher concentration and 12 h DIM treatments at 2 μg mL−1 or higher concentration induced significant larval mortality and metamorphic abnormality in the bryozoan Bugula Neritina. The bioassay results correlated with the dose-dependent up-regulation of HSP family proteins, pro-apoptotic proteins, ubiquitination protein, and the dose-dependent down-regulation of anti-apoptotic genes and developmental genes. Unexpectedly, genes involved in fatty acid biosynthesis and protein synthesis were up-regulated in response to DIM treatment, but, in general, the effects of DIM on B. Neritina larvae were comparable to that reported in human cancer cell lines. DIM also induced changes in steroid hormone biosynthesis genes in B. Neritina larvae, leading to the concern that DIM might have long-term effects on marine lives. Overall, the present study suggested that application of DIM to the bryozoan larvae would trigger a major transcriptomic response, which might be linked to the observed larval mortality and abnormality. We suggest that application of DIM as an antifouling ingredient should be proceeded with great cautions.
-
exploring the regulatory role of nitric oxide no and the no p38mapk cgmp pathway in larval settlement of the bryozoan bugula Neritina
Biofouling, 2018Co-Authors: Xiao-xue Yang, Yu Zhang, Yue Him Wong, Gen Zhang, Peiyuan QianAbstract:The bryozoan Bugula Neritina is a cosmopolitan marine fouling species that causes major fouling problems in sub-tropical waters. Settlement of B. Neritina larvae can be triggered without an obvious external cue. Here, the negative regulatory role of nitric oxide (NO) during larval settlement of B. Neritina was demonstrated to be mediated by cyclic guanosine monophosphate (cGMP). Although the regulatory role of the NO-p38 MAPK signaling axis in larval settlement was not evident, inhibition of nitric oxide synthase (NOS) led to the deactivation of p38 MAPK. Exclusive localization of NO and NO signaling components in sensory-related organs of the larvae is consistent with its signal transduction function in metamorphosis. Overall, this study provides new insights into the regulatory roles of the NO-p38MAPK/cGMP pathway in B. Neritina settlement.
-
Exploring the regulatory role of nitric oxide (NO) and the NO-p38MAPK/cGMP pathway in larval settlement of the bryozoan Bugula Neritina
Biofouling, 2018Co-Authors: Xiao-xue Yang, Yu Zhang, Yue Him Wong, Zhang, Peiyuan QianAbstract:The bryozoan Bugula Neritina is a cosmopolitan marine fouling species that causes major fouling problems in sub-tropical waters. Settlement of B. Neritina larvae can be triggered without an obvious external cue. Here, the negative regulatory role of nitric oxide (NO) during larval settlement of B. Neritina was demonstrated to be mediated by cyclic guanosine monophosphate (cGMP). Although the regulatory role of the NO-p38 MAPK signaling axis in larval settlement was not evident, inhibition of nitric oxide synthase (NOS) led to the deactivation of p38 MAPK. Exclusive localization of NO and NO signaling components in sensory-related organs of the larvae is consistent with its signal transduction function in metamorphosis. Overall, this study provides new insights into the regulatory roles of the NO-p38MAPK/cGMP pathway in B. Neritina settlement.
-
HSP90 regulates larval settlement of the bryozoan Bugula Neritina through the nitric oxide pathway.
The Journal of Experimental Biology, 2018Co-Authors: Xiao-xue Yang, Yu Zhang, Yue Him WongAbstract:ABSTRACT The larvae of many sessile marine invertebrates go through a settlement process, during which planktonic larvae attach to a substrate and metamorphose into sessile juveniles. Larval attachment and metamorphosis (herein defined as ‘settlement’) are complex processes mediated by many signalling pathways. Nitric oxide (NO) signalling is one of the pathways that inhibits larval settlement in marine invertebrates across different phyla. NO is synthesized by NO synthase (NOS), which is a client of the molecular chaperone heat shock protein 90 (HSP90). In the present study, we provide evidence that NO, a gaseous messenger, regulates larval settlement of Bugula Neritina . By using pharmacological bioassays and western blotting, we demonstrated that NO inhibits larval settlement of B. Neritina and that NO signals occur mainly in the sensory organ of swimming larvae. The settlement rate of B. Neritina larvae decreased after heat shock treatment. Inhibition of HSP90 induced larval settlement, and attenuated the inhibition of NO donors during larval settlement. In addition, the expression level of both HSP90 and NOS declined upon settlement. These results demonstrate that HSP90 regulates the larval settlement of B. Neritina by interacting with the NO pathway.
-
The regulatory role of arginine kinase during larval settlement of the bryozoan Bugula Neritina
Marine Biology, 2018Co-Authors: Yu Zhang, Xiao-xue Yang, Yue Him WongAbstract:Larval attachment and metamorphosis, also collectively known as settlement, plays an important role in the life history of marine invertebrates with biphasic life cycle. Bugula Neritina can settle on any substrate without substrate selection. This complex transformation usually involves an active selection process, while the larval decision to settle is regulated by both exogenous and endogenous factors. This study focuses on the involvement of arginine kinase (AK), an important enzyme that regulates energy metabolism in marine invertebrates, during larval settlement of the bryozoan Bugula Neritina. We reveal that AK was highly expressed in the swimming larvae of B. Neritina, while its expression was down-regulated post-attachment. When treated with AK inhibitors, the larval settlement rate was significantly decreased. In addition, the immunostaining results indicated that AK was mainly localized to the neuro-muscular cord in swimming larvae. Overall, our results suggest the involvement of AK in regulating larval settlement of B. Neritina.
Seana K Davidson - One of the best experts on this subject based on the ideXlab platform.
-
localization of candidatus endobugula sertula and the bryostatins throughout the life cycle of the bryozoan bugula Neritina
The ISME Journal, 2007Co-Authors: Seana K Davidson, Koty H. Sharp, Margo G. HaygoodAbstract:‘Candidatus Endobugula sertula,’ the uncultivated γ-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.
-
evidence for the biosynthesis of bryostatins by the bacterial symbiont candidatus endobugula sertula of the bryozoan bugula Neritina
Applied and Environmental Microbiology, 2001Co-Authors: Seana K Davidson, Scott W Allen, Christine Anderson, Margo G. HaygoodAbstract:The marine bryozoan, Bugula Neritina, is the source of the bryostatins, a family of macrocyclic lactones with anticancer activity. Bryostatins have long been suspected to be bacterial products. B. Neritina harbors the uncultivated gamma proteobacterial symbiont “Candidatus Endobugula sertula.” In this work several lines of evidence are presented that show that the symbiont is the most likely source of bryostatins. Bryostatins are complex polyketides similar to bacterial secondary metabolites synthesized by modular type I polyketide synthases (PKS-I). PKS-I gene fragments were cloned from DNA extracted from the B. Neritina-“E. sertula” association, and then primers specific to one of these clones, KSa, were shown to amplify the KSa gene specifically and universally from total B. Neritina DNA. In addition, a KSa RNA probe was shown to bind specifically to the symbiotic bacteria located in the pallial sinus of the larvae of B. Neritina and not to B. Neritina cells or to other bacteria. Finally, B. Neritina colonies grown in the laboratory were treated with antibiotics to reduce the numbers of bacterial symbionts. Decreased symbiont levels resulted in the reduction of the KSa signal as well as the bryostatin content. These data provide evidence that the symbiont E. sertula has the genetic potential to make bryostatins and is necessary in full complement for the host bryozoan to produce normal levels of bryostatins. This study demonstrates that it may be possible to clone bryostatin genes from B. Neritina directly and use these to produce bryostatins in heterologous host bacteria.
-
identification of sibling species of the bryozoan bugula Neritina that produce different anticancer bryostatins and harbor distinct strains of the bacterial symbiont candidatus endobugula sertula
The Biological Bulletin, 1999Co-Authors: Seana K Davidson, Margo G. HaygoodAbstract:Although the cosmopolitan marine bryozoan Buga chemotype M lacks bryostatins with the octa-2,4- dienoate substituent. B. Neritina contains a symbiotic y-pro- teobacterium "Cundidutus Endobugula sertula," and it has been proposed that bryostatins may be synthesized by bac- terial symbionts. In this study, B. Neritina populations along the California coast were sampled for genetic variation and bryostatin content. Colonies that differ in chemotype also differ genetically by 8% in the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene; this difference is sufficient to suggest that the chemotypes represent different species. Each species contains a distinct strain of "E. sertula" that differs at four nucleotide sites in the small subunit ribo- somal RNA (SSU rRNA) gene. These results indicate that the chemotypes have a genetic basis rather than an environ- mental cause. Gene sequences from an Atlantic sample matched sequences from the California chemotype M col- onies, suggesting that this type may be cosmopolitan due to transport on boat hulls.
-
identification of sibling species of the bryozoan bugula Neritina that produce different anticancer bryostatins and harbor distinct strains of the bacterial symbiont candidatus endobugula sertula
The Biological Bulletin, 1999Co-Authors: Seana K Davidson, Margo G. HaygoodAbstract:Although the cosmopolitan marine bryozoan Bugula Neritina is recognized as a single species, natural products from this bryozoan vary among populations. B. Neritina is the source of the anticancer drug candidate bryostatin 1, but it also produces other bryostatins, and different populations contain different bryostatins. We defined two chemotypes on the basis of previous studies: chemotype O contains bryostatins with an octa-2,4-dienoate substituent (including bryostatin 1), as well as other bryostatins; chemotype M lacks bryostatins with the octa-2,4-dienoate substituent. B. Neritina contains a symbiotic gamma-proteobacterium "Candidatus Endobugula sertula," and it has been proposed that bryostatins may be synthesized by bacterial symbionts. In this study, B. Neritina populations along the California coast were sampled for genetic variation and bryostatin content. Colonies that differ in chemotype also differ genetically by 8% in the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene; this difference is sufficient to suggest that the chemotypes represent different species. Each species contains a distinct strain of "E. sertula" that differs at four nucleotide sites in the small subunit ribosomal RNA (SSU rRNA) gene. These results indicate that the chemotypes have a genetic basis rather than an environmental cause. Gene sequences from an Atlantic sample matched sequences from the California chemotype M colonies, suggesting that this type may be cosmopolitan due to transport on boat hulls.
-
biology of the bryostatins in the marine bryozoan bugula Neritina symbiosis cryptic speciation and chemical defense
California Sea Grant College Program, 1999Co-Authors: Seana K DavidsonAbstract:Author(s): Davidson, Seana K. | Abstract: This dissertation investigates the identity and function of a bacterial symbiont described in the marine bryozoan Bugula Neritina by R.M. Woollacott in 1981. B. Neritina is the source of bryostatins, unique cytotoxins suspected to have a bacterial source, and is considered a single species throughout its cosmopolitan temperate range. Bryostatins found from different collections of B. Neritina vary, and only certain populations produce bryostatins that possess an octa-2,4-dienoate substituent. In this dissertation the bacterial symbionts of the larvae are identified by small subunit ribosomal rRNA {SSU) gene sequences and named "Candidatus Endobugula sertula." The variable regions of these genes were used to design oligonucleotides specific to the symbiont. These specific oligonucleotides were used for in situ hybridization to the bacteria in the pallial sinus to confirm the origin of the sequence, and for specific amplification of symbiont SSU rRNA genes by PCR. Then the mitochondrial cytochrome c oxidase subunit I gene was used to identify two distinct species of B. Neritina each harboring a different symbiont as determined by SSU rRNA sequence. Variation in the bryostatin profiles is associated with this genetic difference. Only one B. Neritina/"E. sertula" association can produce bryostatins with an octa-2,4-dienoate substituent (bryostatins 1-3, 12 and 15). In order to elucidate the possible involvement of the symbiont in production of bryostatins, experiments were conducted to eliminate "E. sertula" from R. Neritina to determine whether B. Neritina can continue to grow normally without the symbiont, and/or continue to produce equivalent levels of bryostatins. Symbiont levels were estimated using a symbiont-specific PCR assay, then bryostatin activity levels were compared between control and treated B. Neritina colonies. When symbiont levels were greatly reduced, bryostatin activity declined by approximately 50%. Genetic evidence was discovered that indicates "E. sertuld" has the potential to synthesize complex polyketides like bryostatin. Finally evidence was gathered to address the hypothesis that bryostatins serve as defensive compounds for the bryozoan host. The distribution of bryostatins in the colonies is suggestive of a defense, and it was found that predatory nudibranchs of B. Neritina sequester bryostatins and concentrate them in their egg ribbons. In summary, the symbiont's most likely function is to provide a chemical defense, bryostatins, for the host.
