Experimental evidence that ovary and oviducal gland extracts influence male agonistic behavior in squids

Author Posting. © Marine Biological Laboratory, 2004. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 206 (2004): 1-3.Recent investigations of sensory and behavioral cues that initiate sexual selection processes in the squid Loligo pealeii have determined that egg capsules deposited on the substrate provide a strong visual and chemotactile stimulus to males, even in the absence of females (1, 2, 3). The visual stimulus of egg capsules attracts males to the eggs, and when the males touch the eggs, they encounter a chemical stimulus that leads to highly aggressive fighting behavior. We have recently demonstrated that egg capsule extracts implanted in artificial egg capsules elicit this aggressive behavior (4). In this communication, we present evidence that the salient chemical factor originates in the ovary and perhaps the oviducal gland of the female reproductive tract

Male Accessory Gland Protein Reduces Egg Laying in a Simultaneous Hermaphrodite

Seminal fluid is an important part of the ejaculate of internally fertilizing animals. This fluid contains substances that nourish and activate sperm for successful fertilization. Additionally, it contains components that influence female physiology to further enhance fertilization success of the sperm donor, possibly beyond the recipient's optimum. Although evidence for such substances abounds, few studies have unraveled their identities, and focus has been exclusively on separate-sex species. We present the first detailed study into the seminal fluid composition of a hermaphrodite (Lymnaea stagnalis). Eight novel peptides and proteins were identified from the seminal-fluid-producing prostate gland and tested for effects on oviposition, hatching and consumption. The gene for the protein found to suppress egg mass production, Ovipostatin, was sequenced, thereby providing the first fully-characterized seminal fluid substance in a simultaneous hermaphrodite. Thus, seminal fluid peptides and proteins have evolved and can play a crucial role in sexual selection even when the sexes are combined

Melt generation, crystallization, and extraction beneath segmented oceanic transform faults

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): B11102, doi:10.1029/2008JB006100.We examine mantle melting, fractional crystallization, and melt extraction beneath fast slipping, segmented oceanic transform fault systems. Three-dimensional mantle flow and thermal structures are calculated using a temperature-dependent rheology that incorporates a viscoplastic approximation for brittle deformation in the lithosphere. Thermal solutions are combined with the near-fractional, polybaric melting model of Kinzler and Grove (1992a, 1992b, 1993) to determine extents of melting, the shape of the melting regime, and major element melt composition. We investigate the mantle source region of intratransform spreading centers (ITSCs) using the melt migration approach of Sparks and Parmentier (1991) for two end-member pooling models: (1) a wide pooling region that incorporates all of the melt focused to the ITSC and (2) a narrow pooling region that assumes melt will not migrate across a transform fault or fracture zone. Assuming wide melt pooling, our model predictions can explain both the systematic crustal thickness excesses observed at intermediate and fast slipping transform faults as well as the deeper and lower extents of melting observed in the vicinity of several transform systems. Applying these techniques to the Siqueiros transform on the East Pacific Rise we find that both the viscoplastic rheology and wide melt pooling are required to explain the observed variations in gravity inferred crustal thickness. Finally, we show that mantle potential temperature Tp = 1350°C and fractional crystallization at depths of 9–15.5 km fit the majority of the major element geochemical data from the Siqueiros transform fault system.This research was supported by WHOI Academic Programs Office (PMG), NSF grants OCE-0649103 and OCE-0623188 (MDB), and the Charles D. Hollister Endowed Fund for Support of Innovative Research at WHOI (J.L.)

Candidate chemoreceptor subfamilies differentially expressed in the chemosensory organs of the mollusc Aplysia

<p>Abstract</p> <p>Background</p> <p>Marine molluscs, as is the case with most aquatic animals, rely heavily on olfactory cues for survival. In the mollusc <it>Aplysia californica</it>, mate-attraction is mediated by a blend of water-borne protein pheromones that are detected by sensory structures called rhinophores. The expression of G protein and phospholipase C signaling molecules in this organ is consistent with chemosensory detection being via a G-protein-coupled signaling mechanism.</p> <p>Results</p> <p>Here we show that novel multi-transmembrane proteins with similarity to rhodopsin G-protein coupled receptors are expressed in sensory epithelia microdissected from the <it>Aplysia </it>rhinophore. Analysis of the <it>A. californica </it>genome reveals that these are part of larger multigene families that possess features found in metazoan chemosensory receptor families (that is, these families chiefly consist of single exon genes that are clustered in the genome). Phylogenetic analyses show that the novel <it>Aplysia </it>G-protein coupled receptor-like proteins represent three distinct monophyletic subfamilies. Representatives of each subfamily are restricted to or differentially expressed in the rhinophore and oral tentacles, suggesting that they encode functional chemoreceptors and that these olfactory organs sense different chemicals. Those expressed in rhinophores may sense water-borne pheromones. Secondary signaling component proteins Gα_q, Gα_i, and Gα_oare also expressed in the rhinophore sensory epithelium.</p> <p>Conclusion</p> <p>The novel rhodopsin G-protein coupled receptor-like gene subfamilies identified here do not have closely related identifiable orthologs in other metazoans, suggesting that they arose by a lineage-specific expansion as has been observed in chemosensory receptor families in other bilaterians. These candidate chemosensory receptors are expressed and often restricted to rhinophores and oral tentacles, lending support to the notion that water-borne chemical detection in <it>Aplysia </it>involves species- or lineage-specific families of chemosensory receptors.</p

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The Egg-Laying Hormone Family: Precursors, Products, and Functions

Volume: 177Start Page: 210End Page: 21

Behavioral Characterization of Attractin, a Water-Borne Peptide Pheromone in the Genus Aplysia

Volume: 205Start Page: 16End Page: 2

Conservation of the egg-laying hormone neuropeptide and attractin pheromone in the spotted sea hare, Aplysia dactylomela

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