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Gregg T. Nagle – One of the best experts on this subject based on the ideXlab platform.

  • Conservation of the egg-laying hormone neuropeptide and Attractin pheromone in the spotted sea hare, Aplysia dactylomela.
    Peptides, 2009
    Co-Authors: Scott F Cummins, Gregg T. Nagle, Parinyaporn Nuurai, Bernard M. Degnan

    Abstract:

    In the marine opisthobranch mollusc, Aplysia, secreted peptides and proteins play an essential role in egg laying and mate attraction. Aplysia californica egg laying is initiated by secretion of the egg-laying hormone (ELH) peptide while mate attraction is made possible by protein pheromones, such as Attractin, released into the surrounding seawater with the egg cordon. In this study, we investigated the existence of similar egg-laying hormone and Attractin products in the spotted sea hare, Aplysia dactylomela, a species that is widely distributed in almost all tropical and temperate oceans, including Australia’s Great Barrier Reef. Immunological analysis revealed that an ELH-like transmitter is present within bag cell somata and processes of the abdominal ganglion. A molecular genetic approach found that the ELH precursor mRNA is synthesized in the abdominal ganglia and encodes a 36-residue peptide (dELH) that is cleaved from the prohormone prior to secretion. It is most closely related to A. californica and A. brasiliana ELH (91.7% identical). We also found that A. dactylomela synthesize an Attractin pheromone in the albumen gland that is released during egg laying. The gene encodes a 58-residue mature protein that is 74.9% similar to A. californica Attractin. We demonstrate that an increase in seawater temperature can disrupt Attractins higher order interactions, such as those with the pheromone temptin, and accelerates Attractin degradation. Together, these findings further expands our understanding of pheromone intermolecular interactions and presents an opportunity for further study of how increases in sea water temperature may affect this important marine communication system.

  • Characterization of Aplysia Alb-1, a candidate water-borne protein pheromone released during egg laying.
    Peptides, 2007
    Co-Authors: Scott F Cummins, Bernard M. Degnan, Gregg T. Nagle

    Abstract:

    Pheromones are known to be important to the innate behavior of marine animals. Attraction in Aplysia involves the long-distance water-borne protein pheromones Attractin, enticin, temptin and seductin, which are released from the albumen gland during egg laying. Other pheromones are predicted to act in concert with these pheromones, but their identities are unknown. To identify additional pheromone candidates, we employed differential library screening of an albumen gland cDNA library, RT-PCR, recombinant protein expression, rhinophore contraction bioassays and immunocytochemistry. Alb-1 is expressed in the Aplysia californica albumen gland and encodes a novel protein that does not share significant sequence identity with any proteins in the database. RT-PCR analysis detected Alb-1 transcripts in the albumen gland, exocrine atrial gland and ovotestis. The Alb-1 precursor has a signal peptide sequence followed by a predicted 101-residue protein sequence containing eight cysteine residues. Recombinant protein expression, RP-HPLC, microsequence analysis and MALDI mass spectrometry analyses demonstrated that mature recombinant Alb-1 was processed at a paired basic residue site to generate an N-terminal and C-terminal protein fragment; this was consistent with immunoblot observations on purified albumen gland extracts. In rhinophore contraction (twitch) bioassays, the recombinant N-terminal protein induced rhinophore contractions whereas the C-terminal protein did not. An antibody generated to the N-terminal protein was used for immunocytochemical and immunoblot analyses and demonstrated that this protein is present in albumen gland secretory cells, egg cordons and egg eluates. Overall, the data suggest that Alb-1 may be processed in the albumen gland and that the Alb-11–56 protein released during egg laying may serve a pheromonal function in concert with Attractin, enticin, temptin and seductin.

  • Aplysia temptin – the ‘glue’ in the water-borne Attractin pheromone complex.
    The FEBS journal, 2007
    Co-Authors: Scott F Cummins, Gregg T. Nagle, Jonathan V Sweedler, Bernard M. Degnan, Fang Xie, Melissa R. De Vries, Suresh P. Annangudi, Milind Misra, Catherine H Schein

    Abstract:

    Temptin, a component of the complex of water-borne protein pheromones that stimulate attraction and mating behavior in the marine mollusk Aplysia, has sequence homology to the epidermal growth factor (EGF)-like domains of higher organisms that mediate protein-cell surface contact during fertilization and blood coagulation. In this work, recombinant temptin for structural and functional studies was produced in Escherichia coli using a cold shock promoter and purified by RP-HPLC. CD spectra confirmed a predominantly beta-sheet structure. Two disulfide bonds were determined via limited proteolysis and MS. One internal disulfide (Cys57-Cys77) was predicted from initial alignments with class I EGF-like domains; the second, between Cys18 and Cys103, could protect temptin against proteolysis in seawater and stabilize its interacting surface. A three-dimensional model of temptin was prepared with our MPACK suite, based on the Ca2+-binding, EGF-like domain of the extracellular matrix protein fibrillin. Two temptin residues, Trp52 and Trp79, which align with cysteine residues conserved in fibrillins, lie adjacent to and could stabilize the disulfide bonds and a proposed metal-binding loop. The water-borne pheromone Attractin in egg cordon eluates is complexed with other proteins. Docking results with our model and the NMR structure of Attractin suggest that one face of temptin interacts with the pheromone, perhaps controlling its access to the cellular receptors. Gel shifts confirmed that temptin complexes with wild-type Attractin. These results indicate that temptin, analogous to the role of fibrillin in controlling transforming growth factor-beta concentration, modulates pheromone signaling by direct binding to Attractin.

Scott F Cummins – One of the best experts on this subject based on the ideXlab platform.

  • Identification of an Attractin-like pheromone in the mucus-secreting hypobranchial gland of the abalone Haliotis asinina linnaeus.
    Journal of Shellfish Research, 2010
    Co-Authors: Chitraporn Kuanpradit, Scott F Cummins, Bernard M. Degnan, Prapee Sretarugsa, Peter J. Hanna, Prasert Sobhon, Jittipan Chavadej

    Abstract:

    Pheromones are chemicals used to communicate between animals of the same species, and are thought to be used by most marine animals. With limited vision, abalone primarily sense their world chemically, and pheromones may play an important role in settlement, attraction, recognition, alarm, and reproduction. Despite this, there has been no detailed investigation into pheromone substances, both in their precise biochemical nature or pheromonal function. In this study, we investigated the presence of pheromonelike substances from the hypobranchial gland of the abalone Haliotis asinina using bioassays, immunohistochemistry, Western blotting, and reverse-phase high-performance liquid chromatography (RP-HPLC). The hypobranchial gland of many prosobranchial marine molluscs has been classified as a sex auxiliary gland releasing unknown substances during spawning. In our study, cephalic tentacle assays demonstrated that the cell extracts of the hypobranchial gland contain chemical cues that are sensed by conspecifics. An antibody against the sea slug “Attractin” pheromone was used as a probe to localize a similar protein in the mucin-secreting cells of the epithelial lining the hypobranchial gland of both male and female abalone. The approximate molecular weight of this abalone Attractin-like protein is 30 kDa in both males and females. Fractionation of hypobranchial gland extracts by C5 RP-HPLC could not selectively purify this protein, and no sex-specific differences were observed. We predict that the Attractin-like protein could be one of a number of important proteins involved in maturation, aggregation, and/or spawning behavior of abalone. In future research, additional hypobranchial gland components will be tested further for these types of behavior.

  • Conservation of the egg-laying hormone neuropeptide and Attractin pheromone in the spotted sea hare, Aplysia dactylomela.
    Peptides, 2009
    Co-Authors: Scott F Cummins, Gregg T. Nagle, Parinyaporn Nuurai, Bernard M. Degnan

    Abstract:

    In the marine opisthobranch mollusc, Aplysia, secreted peptides and proteins play an essential role in egg laying and mate attraction. Aplysia californica egg laying is initiated by secretion of the egg-laying hormone (ELH) peptide while mate attraction is made possible by protein pheromones, such as Attractin, released into the surrounding seawater with the egg cordon. In this study, we investigated the existence of similar egg-laying hormone and Attractin products in the spotted sea hare, Aplysia dactylomela, a species that is widely distributed in almost all tropical and temperate oceans, including Australia’s Great Barrier Reef. Immunological analysis revealed that an ELH-like transmitter is present within bag cell somata and processes of the abdominal ganglion. A molecular genetic approach found that the ELH precursor mRNA is synthesized in the abdominal ganglia and encodes a 36-residue peptide (dELH) that is cleaved from the prohormone prior to secretion. It is most closely related to A. californica and A. brasiliana ELH (91.7% identical). We also found that A. dactylomela synthesize an Attractin pheromone in the albumen gland that is released during egg laying. The gene encodes a 58-residue mature protein that is 74.9% similar to A. californica Attractin. We demonstrate that an increase in seawater temperature can disrupt Attractins higher order interactions, such as those with the pheromone temptin, and accelerates Attractin degradation. Together, these findings further expands our understanding of pheromone intermolecular interactions and presents an opportunity for further study of how increases in sea water temperature may affect this important marine communication system.

  • Characterization of Aplysia Alb-1, a candidate water-borne protein pheromone released during egg laying.
    Peptides, 2007
    Co-Authors: Scott F Cummins, Bernard M. Degnan, Gregg T. Nagle

    Abstract:

    Pheromones are known to be important to the innate behavior of marine animals. Attraction in Aplysia involves the long-distance water-borne protein pheromones Attractin, enticin, temptin and seductin, which are released from the albumen gland during egg laying. Other pheromones are predicted to act in concert with these pheromones, but their identities are unknown. To identify additional pheromone candidates, we employed differential library screening of an albumen gland cDNA library, RT-PCR, recombinant protein expression, rhinophore contraction bioassays and immunocytochemistry. Alb-1 is expressed in the Aplysia californica albumen gland and encodes a novel protein that does not share significant sequence identity with any proteins in the database. RT-PCR analysis detected Alb-1 transcripts in the albumen gland, exocrine atrial gland and ovotestis. The Alb-1 precursor has a signal peptide sequence followed by a predicted 101-residue protein sequence containing eight cysteine residues. Recombinant protein expression, RP-HPLC, microsequence analysis and MALDI mass spectrometry analyses demonstrated that mature recombinant Alb-1 was processed at a paired basic residue site to generate an N-terminal and C-terminal protein fragment; this was consistent with immunoblot observations on purified albumen gland extracts. In rhinophore contraction (twitch) bioassays, the recombinant N-terminal protein induced rhinophore contractions whereas the C-terminal protein did not. An antibody generated to the N-terminal protein was used for immunocytochemical and immunoblot analyses and demonstrated that this protein is present in albumen gland secretory cells, egg cordons and egg eluates. Overall, the data suggest that Alb-1 may be processed in the albumen gland and that the Alb-11–56 protein released during egg laying may serve a pheromonal function in concert with Attractin, enticin, temptin and seductin.

Catherine H Schein – One of the best experts on this subject based on the ideXlab platform.

  • Aplysia temptin – the ‘glue’ in the water-borne Attractin pheromone complex.
    The FEBS journal, 2007
    Co-Authors: Scott F Cummins, Gregg T. Nagle, Jonathan V Sweedler, Bernard M. Degnan, Fang Xie, Melissa R. De Vries, Suresh P. Annangudi, Milind Misra, Catherine H Schein

    Abstract:

    Temptin, a component of the complex of water-borne protein pheromones that stimulate attraction and mating behavior in the marine mollusk Aplysia, has sequence homology to the epidermal growth factor (EGF)-like domains of higher organisms that mediate protein-cell surface contact during fertilization and blood coagulation. In this work, recombinant temptin for structural and functional studies was produced in Escherichia coli using a cold shock promoter and purified by RP-HPLC. CD spectra confirmed a predominantly beta-sheet structure. Two disulfide bonds were determined via limited proteolysis and MS. One internal disulfide (Cys57-Cys77) was predicted from initial alignments with class I EGF-like domains; the second, between Cys18 and Cys103, could protect temptin against proteolysis in seawater and stabilize its interacting surface. A three-dimensional model of temptin was prepared with our MPACK suite, based on the Ca2+-binding, EGF-like domain of the extracellular matrix protein fibrillin. Two temptin residues, Trp52 and Trp79, which align with cysteine residues conserved in fibrillins, lie adjacent to and could stabilize the disulfide bonds and a proposed metal-binding loop. The water-borne pheromone Attractin in egg cordon eluates is complexed with other proteins. Docking results with our model and the NMR structure of Attractin suggest that one face of temptin interacts with the pheromone, perhaps controlling its access to the cellular receptors. Gel shifts confirmed that temptin complexes with wild-type Attractin. These results indicate that temptin, analogous to the role of fibrillin in controlling transforming growth factor-beta concentration, modulates pheromone signaling by direct binding to Attractin.

  • Newly identified water-borne protein pheromones interact with Attractin to stimulate mate attraction in Aplysia.
    Peptides, 2005
    Co-Authors: Scott F Cummins, Amy E. Nichols, Catherine H Schein, Gregg T. Nagle

    Abstract:

    The water-borne protein Attractin is a potent sex pheromone involved in forming and maintaining mating and egg-laying aggregations in the marine mollusk Aplysia. Binary blends of Attractin and either enticin, temptin, or seductin, three other Aplysia protein pheromones, stimulate mate attraction. The four pheromones are thought to act in concert during egg-laying. The new data presented here show that: (1) the water-borne odor of non-laying Aplysia brasiliana further increases the attractiveness of Attractin and of eggs in T-maze bioassays. This suggests that individual Aplysia release additional factors that enhance the effects of Attractin, enticin, temptin, and seductin during egg-laying; (2) the N-terminal region of enticin aligns well with the conserved epidermal growth factor (EGF)-like domain of mammalian reproductive proteins known as fertilins, which may mediate intercellular adhesion interactions between eggs and sperm; (3) temptin, according to fold recognition servers, may also have an EGF-like fold. Enticin and temptin also have conserved metal binding sequences that may play a role in their signaling behavior. These results suggest that aspects of mammalian egg-sperm interactions (fertilins) may have evolved from pheromonal signaling mechanisms. We also review the structure, expression, localization, release, and behavioral actions of Attractin, enticin, temptin, and seductin.

  • Molluscan Attractins, a family of water-borne protein pheromones with interspecific attractiveness.
    Peptides, 2005
    Co-Authors: Scott F Cummins, Catherine H Schein, Werner Braun, Gregg T. Nagle

    Abstract:

    The marine mollusk Aplysia releases the water-borne pheromone Attractin during egg laying. This small protein stimulates the formation and maintenance of mating and egg-laying aggregations. Attractin has been characterized from five Aplysia species: A. californica, A. brasiliana, A. fasciata, A. vaccaria, and A. depilans. We describe here the isolation of Attractin from Bursatella leachii, and show that it belongs to the same protein family. The pattern of residue conservation, especially the six invariant cysteines, suggests that all of these Attractins have a common fold. The nuclear magnetic resonance solution structure of A. californica Attractin contains two antiparallel α-helices, the second of which contains the heptapeptide sequence IEECKTS that has been implicated in Attractin function. Synthetic peptides containing this IEECKTS region are attractive, and mutating surface exposed charged residues within this region of Attractin abolishes Attractin activity. This suggests that the second helix is an essential part of the receptor-binding interface. In contrast to the peptide pheromonal attractants in amphibians, which are species specific, the Attractins are, to our knowledge, the first water-borne peptide or protein pheromone family in invertebrates and vertebrates that are not species specific.