208 research outputs found
\u3ci\u3e A new species of Foza Reed & Cumberlidge, 2006, From Northern Madagascar \u3c/i\u3e
Oceanographic and biological influences on recruitment of benthic invertebrates to hard substrata on the Oregon shelf
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Estuarine, Coastal and Shelf Science 208 (2018): 1-8, doi:10.1016/j.ecss.2018.04.037.The number of anthropogenic substrata in the ocean – structures like oil rigs and offshore
renewable energy generators – is increasing. These structures provide hard-bottom habitat in
areas previously dominated by sand or mud, so they have the potential to alter species
distributions or serve as “stepping-stones” between other hard-bottom habitats. It is thus
important to understand what factors influence the composition and abundance of benthic fauna
recruiting at these sites. We examined recruitment to hard substrata (fouling panels) deployed on
sand at various distances from a large rocky reef (~60 m isobath) on the southern Oregon coast
in 2014 – 2015. Recruitment was dominated by the acorn barnacle Hesperibalanus hesperius.
For the majority of the study period in 2014, an anti-cyclonic eddy was present near the
deployment sites. However, anomalously high recruitment of H. hesperius during August – early
October 2014 coincided with dissipation of the eddy, slower bottom currents, and a positive
convergence index, suggesting that H. hesperius larvae from the adjacent area may have been
accumulated and retained near our study sites. Other sessile species, including hydroids and
bryozoans, recruited to the fouling panels in low abundances, and most of these species have
long-range dispersal and fast growth. Mobile invertebrates observed on the fouling panels
included gastropods and nudibranchs, most of which also have long-range dispersal and fast
growth, and are predators as adults. Thus, a community with two trophic levels assembled on the
fouling panels in a relatively short time period (<12 weeks). None of the common hard-bottom
species from the adjacent rocky reef recruited to the panels, suggesting that there is a specialized
assemblage of species that can exploit hard-bottom habitats surrounded by sandy plains. Our
results raise many questions about the influences of dispersal and oceanographic conditions on
recruitment to hard substrata.This material is based upon work supported by the National Science Foundation Graduate
Research Fellowship Program under Grant No. DGE-0829517. YL is partially supported by the Dr. George
Grice Postdoctoral Scholarship from Woods Hole Oceanographic Institution, with support from
NSF grant #1634965
New collections of freshwater crabs from northern Madagascar, with the description of a new species of Foza Reed & Cumberlidge, 2006 (Brachyura, Potamonautidae), and comments on their conservation status
Chromatin Composition Is Changed by Poly(ADP-ribosyl)ation during Chromatin Immunoprecipitation
Chromatin-immunoprecipitation (ChIP) employs generally a mild formaldehyde cross-linking step, which is followed by isolation of specific protein-DNA complexes and subsequent PCR testing, to analyze DNA-protein interactions. Poly(ADP-ribosyl)ation, a posttranslational modification involved in diverse cellular functions like repair, replication, transcription, and cell death regulation, is most prominent after DNA damage. Poly(ADP-ribose)polymerase-1 is activated upon binding to DNA strand-breaks and coordinates repair by recruitment or displacement of proteins. Several proteins involved in different nuclear pathways are directly modified or contain poly(ADP-ribose)-interaction motifs. Thus, poly(ADP-ribose) regulates chromatin composition. In immunofluorescence experiments, we noticed artificial polymer-formation after formaldehyde-fixation of undamaged cells. Therefore, we analyzed if the formaldehyde applied during ChIP also induces poly(ADP-ribosyl)ation and its impact on chromatin composition. We observed massive polymer-formation in three different ChIP-protocols tested independent on the cell line. This was due to induction of DNA damage signaling as monitored by γH2AX formation. To abrogate poly(ADP-ribose) synthesis, we inhibited this enzymatic reaction either pharmacologically or by increased formaldehyde concentration. Both approaches changed ChIP-efficiency. Additionally, we detected specific differences in promoter-occupancy of tested transcription factors as well as the in the presence of histone H1 at the respective sites. In summary, we show here that standard ChIP is flawed by artificial formation of poly(ADP-ribose) and suppression of this enzymatic activity improves ChIP-efficiency in general. Also, we detected specific changes in promoter-occupancy dependent on poly(ADP-ribose). By preventing polymer synthesis with the proposed modifications in standard ChIP protocols it is now possible to analyze the natural chromatin-composition
Desperate planktotrophs : decreased settlement selectivity with age in competent eastern oyster Crassostrea virginica larvae
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 599 (2018): 93-106, doi:10.3354/meps12653.For larvae of benthic marine invertebrate species, settlement from planktonic to benthic
life is a critical transition. The “desperate larva” concept describes the tendency of larvae to
accept suboptimal settlement habitats as they age. We quantified swimming behavior in
planktotrophic larvae of the eastern oyster, Crassostrea virginica, to determine whether
settlement behaviors, such as swimming downward and remaining on the bottom, increased with
age and whether these ontogenetic changes were more apparent in larvae exposed to suboptimal
conditions than to preferred conditions (settlement cue absent or present, respectively). In two
experiments, the proportion of competent larvae remaining near the bottom of experimental
flasks (indicating settlement) increased with larval age, but only in larvae that were not exposed
to the settlement cue. This result is consistent with the hypothesis that larvae encountering
suboptimal habitat become “desperate” (i.e. more likely to settle) as they age. Exploratory
behaviors, such as upward swimming, meandering, or helices, were expected to decrease with
age, especially in the absence of the settlement cue, but this pattern was detected in only one of
the five swimming metrics tested (helices in downward swimming larvae). Surprisingly, pre-competent larvae exhibited settlement behavior when exposed to the cue, raising the question of
whether a response at this stage would have positive or negative consequences. Acceptance of
suboptimal settlement habitats by aging larvae may increase the resilience of a species by
allowing populations to persist in variable environmental conditions.Funding was provided by NSF grant OCE-0850419, NOAA Sea Grant
NA14OAR4170074, grants from WHOI Coastal Ocean Institute, discretionary WHOI funds, a
WHOI Ocean Life Fellowship to LSM, a WHOI Summer Student Fellowship to EH, and a
WHOI Postdoctoral Scholarship to KSM
Language in the Mathematics Classroom: An introduction to the papers and presentations within ETC 7
Research considering the role of language in the teaching and learning of mathematics continues to grow and develop, drawing on a range of theoretical, methodological and pedagogical approaches. In this introduction, we detail the discussions had and issues raised at the 7th ERME Topic Conference as a result of the bringing together of the theoretical perspectives, foci and findings of the papers presented that are included in these proceedings. These rich discussions also raised new challenges for those researching language and mathematics and identified new possibilities for the future work of the Mathematics and Language thematic working group. Keywords: Language and mathematics, multilingual contexts, meaning-making, interaction<br/
Language in the Mathematics Classroom: An introduction to the papers and presentations within ETC 7
Invertebrate communities on historical shipwrecks in the western Atlantic : relation to islands
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 566 (2017): 17-29, doi:10.3354/meps12058.Shipwrecks can be considered island-like habitats on the seafloor. We investigated the fauna of eight historical shipwrecks off the east coast of the U.S. to assess whether species distribution patterns on the shipwrecks fit models from classical island theory. Invertebrates on the shipwrecks included both sessile (sponges, anemones, hydroids) and motile (crustaceans, echinoderms) species. Invertebrate communities were significantly different among wrecks. The size and distance between wrecks influenced the biotic communities, much like on terrestrial islands. However, while wreck size influenced species richness (alpha diversity), distance to the nearest wreck influenced community composition (beta diversity). Alpha and beta diversity on the shipwrecks were thus influenced by different abiotic factors. We found no evidence of either nested patterns or non-random co-occurrence of morphotypes, suggesting that the taxa on a given shipwreck were randomly selected from the available taxon pool. Species present on the shipwrecks generally had one of two reproductive modes: most motile or solitary sessile species had long-duration planktotrophic larvae, while most encrusting or colonial sessile species had short-duration lecithotrophic larvae and underwent asexual reproduction by budding as adults. Short-duration larvae may recruit to their natal shipwreck, allowing them to build up dense populations and dominate the wreck surfaces. A high degree of dominance was indeed observed on the wrecks, with up to 80% of the fauna being accounted for by the most common species alone. By comparing the shipwreck communities to known patterns of succession in shallow water, we hypothesize that the shipwrecks are in a stage of mid-succession.This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-0829517. Funding for this project was supplied by the Bureau of Ocean Energy Management (BOEM), under contract to CSA Ocean Sciences, Inc. (contract M10PC00100) in partnership with the National Oceanographic 377 Partnership Program
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