Biological Bulletin | Page 2

K S Harms, A V Hesketh, L R Page
Pyramidellids are tiny ectoparasitic gastropods with highly derived feeding structures for piercing and sucking. We attempted to resolve homology controversies about unique pyramidellid feeding structures by examining foregut development through larval and metamorphic stages, using sections for light and electron microscopy. We anticipated that, like many marine invertebrate larvae, post-metamorphic structures would differentiate extensively in late larvae to speed metamorphic transition. Previous studies of gastropods suggested that development of juvenile feeding structures in larvae was facilitated by foregut subdivision into dorsal and ventral developmental modules, and spatial uncoupling of these modules may have facilitated adaptive radiation in neogastropods...
December 2019: Biological Bulletin
Shumpei Yamakawa, Yoshiaki Morino, Masanao Honda, Hiroshi Wada
No abstract text is available yet for this article.
December 2019: Biological Bulletin
Gabriel A Delgado, Robert A Glazer, Nancy J Brown-Peterson
In the Florida Keys, queen conchs ( Lobatus gigas ) occur in two spatially distinct regions: nearshore in habitats immediately adjacent to the shoreline and offshore in habitats along the reef tract south of the islands. Our previous research demonstrated that adult conchs nearshore are not reproductively active, showing deficiencies in their gonadal condition compared to their offshore counterparts. Because sexual development in gastropods is controlled by hormones secreted by the cerebral ganglia, we hypothesized that the reproductive deficiencies seen in nearshore queen conchs involved the cerebral ganglia...
December 2019: Biological Bulletin
S T Abdel-Raheem, Jonathan D Allen
Animals that reside, reproduce, and develop in nearshore habitats are often exposed to strong fluctuations in abiotic conditions, including temperature and salinity. We studied the developmental response of the sand dollar Dendraster excentricus to increased temperature and reduced salinity at levels comparable to those induced by summer freshwater input into the San Juan Archipelago, Washington. We observed that embryos exposed to temperature and salinity stress exhibited polyembryony (the splitting of one embryo into multiple independent individuals), and we subsequently tested the competency of twin and normal embryos to reach metamorphosis...
December 2019: Biological Bulletin
Lisa A Cameron
No abstract text is available yet for this article.
December 2019: Biological Bulletin
Christopher D Wells, Larry G Harris
Failed invasions can be a key component for understanding and controlling introduced populations because understanding mechanisms behind failures can improve effective controls. In 2000, the non-native sea anemone Sagartia elegans was first found in Salem, Massachusetts, and it recolonized each summer. No individuals of S. elegans have been found after 2010, despite intensive search efforts. A mismatch between the species' thermal tolerance and winter water temperature is the most likely mechanism for this failed invasion...
December 2019: Biological Bulletin
Eduardo M García-Roger, Esther Lubzens, Diego Fontaneto, Manuel Serra
An in-depth look at the basic aspects of dormancy in cyclic parthenogenetic organisms is now possible thanks to research efforts conducted over the past two decades with rotifer dormant embryos. In this review, we assemble and compose the current knowledge on four central themes: (1) distribution of dormancy in animals, with an overview on the phylogenetic distribution of embryo dormancy in metazoans, and (2) physiological and cellular processes involved in dormancy, with a strong emphasis on the dormant embryos of cyclically parthenogenetic monogonont rotifers; and discussions of (3) the selective pressures and (4) the evolutionary and population implications of dormancy in these animals...
October 2019: Biological Bulletin
Benni Winding Hansen
Long-lasting embryonic dormancy in invertebrates defies our understanding of what constitutes life because, for example, eggs of some copepods can delay hatching for decades or even centuries. Copepods, often millimeter-sized crustaceans, are some of the most numerous multicellular organisms on earth and are key organisms in most aquatic food webs. Some important free-living marine and estuarine species overwinter or oversummer by arrested embryogenesis in dormancy. The present contribution discusses the complex mechanisms behind embryonic dormancy by compiling knowledge from the 42 calanoid copepods from the superfamily Centropagoidea with well-described embryonic dormancy, which has been of scientific interest for decades...
October 2019: Biological Bulletin
Elise Skottene, Ann M Tarrant, Anders J Olsen, Dag Altin, Bjørn Henrik Hansen, Marvin Choquet, Rolf Erik Olsen, Bjørn M Jenssen
Calanus finmarchicus and Calanus glacialis are keystone zooplankton species in North Atlantic and Arctic marine ecosystems because they form a link in the trophic transfer of nutritious lipids from phytoplankton to predators on higher trophic levels. These calanoid copepods spend several months of the year in deep waters in a dormant state called diapause, after which they emerge in surface waters to feed and reproduce during the spring phytoplankton bloom. Disruption of diapause timing could have dramatic consequences for marine ecosystems...
October 2019: Biological Bulletin
Ann M Tarrant
No abstract text is available yet for this article.
October 2019: Biological Bulletin
Julie A Reynolds
Dormancy is evolutionarily widespread and can take many forms, including diapause, dauer formation, estivation, and hibernation. Each type of dormancy is characterized by distinct features; but accumulating evidence suggests that each is regulated by some common processes, often referred to as a common "toolkit" of regulatory mechanisms, that likely include noncoding RNAs that regulate gene expression. Noncoding RNAs, especially microRNAs, are well-known regulators of biological processes associated with numerous dormancy-related processes, including cell cycle progression, cell growth and proliferation, developmental timing, metabolism, and environmental stress tolerance...
October 2019: Biological Bulletin
Alexandra A Mushegian, Kévin Tougeron
Dormancy and diapause are key adaptations in many organisms, enabling survival of temporarily or seasonally unsuitable environmental conditions. In this review, we examine how our understanding of programmed developmental and metabolic arrest during diapause intersects with the increasing body of knowledge about animal co-development and co-evolution with microorganisms. Host-microbe interactions are increasingly understood to affect a number of metabolic, physiological, developmental, and behavioral traits and to mediate adaptations to various environments...
October 2019: Biological Bulletin
Kristina Øie Kvile, Carin Ashjian, Rubao Ji
Diapause at depth is considered an integral part of the life cycle of Calanus copepods, but few studies have focused on the Arctic species Calanus glacialis and Calanus hyperboreus . By analyzing a large set of pan-arctic observational data compiled from multiple sources, we show that Arctic Calanus has a broad depth distribution in winter, indicating that diapause at depth is a facultative strategy. Both species' vertical distributions tend to deepen in winter and to be deeper and broader with increasing bottom depth, while individuals are aggregated closer to the sea floor in shallow areas...
October 2019: Biological Bulletin
Robert E Steele, Megan D Updegrove, Sara A Kirolos, Lucas Mowery, Daniel E Martínez, Peter J Bryant
Despite the fact that Hydra has been studied for more than 200 years, we know surprisingly little about its life history. We show that Hydra vulgaris embryos hatch sporadically over a period ranging from a few days to nine months. We also report, for what seems to be the first time, the presence of Hydra in a vernal pool. Phylogenetic analysis and sexual crossing show that this Hydra is a member of the cosmopolitan Vulgaris clade and is not reproductively isolated from other members of the clade. Our findings lead us to hypothesize that Hydra evolved in an unstable freshwater habitat in which survival required that its life cycle include the use of a bet-hedging reproductive strategy and the formation of an embryo that is desiccation resistant and that can remain dormant for long periods of time...
October 2019: Biological Bulletin
Petra H Lenz, Vittoria Roncalli
Post-embryonic diapause in copepods is an adaptation that allows species in the copepod family Calanidae to thrive in high-latitude environments by transforming a short spring phytoplankton bloom into large numbers of lipid-rich individuals capable of surviving a long period of starvation. The copepods, with their high-energy lipid reservoirs, are a critical food source for higher trophic levels, making the Calanidae a key component of high-latitude marine ecosystems. The physiological ecology of the developmental program remains poorly understood...
October 2019: Biological Bulletin
Tigran P Norekian, Colin O Hermans, Richard A Satterlie
The pteropod mollusc Clione limacina is a feeding specialist, preying on shelled pteropods of the genus Limacina . Specialized prey-capture structures, called buccal cones, are hydraulically everted from within the mouth to capture the prey. Once captured, the prey is manipulated so the shell opening is over the mouth of Clione . Analyses of high-speed cine sequences of prey capture suggest that the mouth is actively opened rather than passively forced open by buccal cone eversion. The inflated buccal cones are initially straight and form a wide angle (maximum, 113°) prior to prey contact...
August 2019: Biological Bulletin
Mark A Messerli, M Jahir Raihan, Brian M Kobylkevich, Austin C Benson, Kristi S Bruening, Michael Shribak, Joshua J C Rosenthal, Joel J Sohn
The pen, or gladius, of the squid is an internalized shell. It serves as a site of attachment for important muscle groups and as a protective barrier for the visceral organs. The pen's durability and flexibility are derived from its unique composition of chitin and protein. We report the characterization of the structure, development, and composition of pens from Doryteuthis pealeii . The nanofibrils of the polysaccharide β-chitin are arranged in an aligned configuration in only specific regions of the pen...
August 2019: Biological Bulletin
Liam B Doonan, Steven Lynham, Catherine Quinlan, Spike C Ibiji, Carlos E Winter, Gabriel Padilla, Adrian Jaimes-Becerra, André C Morandini, Antonio C Marques, Paul F Long
In this quantitative proteomics study we determined the variety and relative abundance of toxins present in enriched preparations of two nematocyst types isolated from the primary tentacles of the adult medusa stage of the hydrozoan Olindias sambaquiensis . The two nematocyst types were microbasic mastigophores and microbasic euryteles, and these were recovered from the macerated tentacle tissues by using a differential centrifugation approach. Soluble protein extracts from these nematocysts were tagged with tandem mass tag isobaric labels and putative toxins identified using tandem mass spectrometry coupled with a stringent bioinformatics annotation pipeline...
August 2019: Biological Bulletin
Jan A Pechenik, Morgan Levy, Jonathan D Allen
Marine invertebrate larvae have often been reared in artificial rather than natural seawater, either for convenience or to avoid potentially confounding effects of unknown contaminants. This study sought to determine the impact of artificial seawater on various aspects of development for three marine invertebrate species. We examined the impact of Instant Ocean on growth, survival, and fecundity of the deposit-feeding polychaete Capitella teleta at 2 salinities: 24 and 34 ppt; the impact on survival, growth rate, and time to metamorphic competence for the slipper limpet Crepidula fornicata ; and the impact on larval growth for the sea star Asterias forbesi ...
August 2019: Biological Bulletin
Maram N A Almegbel, Emery A Rowe, Fatmah N Alnaser, Mark Yeager, Neil W Blackstone
Metabolic activation can have a profound impact, for instance, by more than compensating for the lower resting metabolic rates of large organisms compared to smaller ones. In some animals, activity can easily be judged by the rate of muscle-driven movement. In sessile organisms, however, judging activity is less straightforward, although feeding often results in metabolic activation. Two colonial cnidarians were examined in this context, using entirely lab-grown material to remove any artifactual effects of experimental manipulations...
August 2019: Biological Bulletin
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