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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 116 (1997), S. 104-112 
    ISSN: 1432-1106
    Keywords: Key words Blink reflex ; Orbicularis oculi ; Clonidine ; Yohimbine ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Neurophysiological studies of the blink reflex to supraorbital nerve stimulation were conducted in eight alert, adult male cats. The cat, like other mammals, shows both short-latency (R1) and long-latency (R2) orbicularis oculi electromyographic (OOemg) components. Measures of OOemg latency, duration, integrated area, and maximum amplitude (MA) were obtained at a stimulus magnitude of 1.5×R2 threshold. The mean (±SE) minimal latencies for R1 and R2 were 8.26±0.85 and 22.97±1.53 ms, respectively. On average, R1 MA was larger than R2 MA. R1 and R2 area measures were similar. Three stimulus paradigms were tested. In a paired-stimulus paradigm, the interstimulus interval (ISI) was randomly varied from 100 to 1200 ms. Ratios were constructed for the OOemg area and MA by dividing the test response by the conditioning response. In this paradigm, although a significant linear relationship was observed only between ISI and R2 MA, conditioning effects were noted on both R1 and R2 area and MA test responses at several ISIs. In a habituation paradigm, both R2 and R1 showed habituation at stimulus frequencies from 0.5 to 2 Hz. In a stimulus-response paradigm, stimulus magnitude was randomly varied between threshold and 2×threshold. In this paradigm, OOemg area and MA of both R1 and R2 were linearly related to stimulus magnitude. Neither the systemically administered centrally acting α2-adrenergic antagonist yohimbine nor agonist clonidine had significant effects on blink reflex parameters, habituation, or the paired-stimulus paradigm. Overall, these results suggest that there are important similarities in the control and modulation of the R1 and R2 components of the blink reflex to supraorbital nerve stimulation in cats.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. 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: Oceans 122 (2017): 1901–1926, doi:10.1002/2016JC012306.
    Description: Photosynthetic conversion of inline image to organic carbon and the transport of this carbon from the surface to the deep ocean is an important regulator of atmospheric inline image. To understand the controls on carbon fluxes in a productive region impacted by upwelling, we measured biological productivity via multiple methods during a cruise in Monterey Bay, California. We quantified net community production and gross primary production from measurements of inline image/Ar and inline image triple isotopes ( inline image), respectively. We simultaneously conducted incubations measuring the uptake of 14C, inline image, and inline image, and nitrification, and deployed sediment traps. At the start of the cruise (Phase 1) the carbon cycle was at steady state and the estimated net community production was 35(10) and 35(8) mmol C m−2 d−1 from inline image/Ar and 15N incubations, respectively, a remarkably good agreement. During Phase 1, net primary production was 96(27) mmol C m−2 d−1 from C uptake, and gross primary production was 209(17) mmol C m−2 d−1 from inline image. Later in the cruise (Phase 2), recently upwelled water with higher nutrient concentrations entered the study area, causing 14C and inline image uptake to increase substantially. Continuous inline image/Ar measurements revealed submesoscale variability in water mass structure and likely productivity in Phase 2 that was not evident from the incubations. These data demonstrate that inline image/Ar and inline image incubation-based NCP estimates can give equivalent results in an N-limited, coastal system, when the nonsteady state inline image fluxes are negligible or can be quantified.
    Description: Funding for this work was provided by NSF awards OCE-1060840 to R.H.R. Stanley, OCE-1129644 to D.P. Nicholson, OCE-1357042 to F.P. Chavez, NASA award NNX14AI06G to M.R. Fewings, the David and Lucile Packard Foundation through their generous annual donation to the Monterey Bay Aquarium Research Institute, an Ocean Ventures Fund award from the WHOI Academic Programs Office to CC Manning, and graduate scholarships from NSERC and CMOS to CC Manning.
    Description: 2017-09-11
    Keywords: Marine productivity ; Carbon cycle ; Dissolved gases
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2019-03-05
    Description: The cyanobacteria Prochlorococcus and Synechococcus are important marine primary producers. We explored their distributions and covariance along a physico-chemical gradient from coastal to open ocean waters in the Northeastern Pacific Ocean. An inter-annual pattern was delineated in the dynamic transition zone where upwelled and eastern boundary current waters mix, and two new Synechococcus clades, Eastern Pacific Clade (EPC) 1 and EPC2, were identified. By applying state-of-the-art phylogenetic analysis tools to bar-coded 16S amplicon datasets, we observed higher abundance of Prochlorococcus high-light I (HLI) and low-light I (LLI) in years when more oligotrophic water intruded farther inshore, while under stronger upwelling Synechococcus I and IV dominated. However, contributions of some cyanobacterial clades were proportionally relatively constant, e.g. Synechococcus EPC2. In addition to supporting observations that Prochlorococcus LLI thrive at higher irradiances than other LL taxa, the results suggest LLI tolerate lower temperatures than previously reported. The phylogenetic precision of our 16S rRNA gene analytical approach and depth of bar-coded sequencing also facilitated detection of clades at low abundance in unexpected places. These include Prochlorococcus at the coast and Cyanobium-related sequences offshore, although it remains unclear whether these came from resident or potentially advected cells. Our study enhances understanding of cyanobacterial distributions in an ecologically important eastern boundary system. © 2014 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.
    Type: Article , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2019-03-05
    Description: Particles in aquatic environments host distinct communities of microbes, yet the evolution of particlespecialized taxa and the extent to which specialized microbial metabolism is associated with particles is largely unexplored. Here, we investigate the hypothesis that a widely distributed and uncultivated microbial group - the marine group II euryarchaea (MGII) - interacts with living and detrital particulate organic matter (POM) in the euphotic zone of the central California Current System. Using fluorescent in situ hybridization, we verified the association of euryarchaea with POM. We further quantified the abundance and distribution of MGII 16S ribosomal RNA genes in size-fractionated seawater samples and compared MGII functional capacity in metagenomes from the same fractions. The abundance of MGII in free-living and 〈3 μm fractions decreased with increasing distance from the coast, whereas MGII abundance in the 0.8-3 lm fraction remained constant. At several offshore sites, MGII abundance was highest in particle fractions, indicating that particle-attached MGII can outnumber free-living MGII under oligotrophic conditions. Compared with free-living MGII, the genome content of MGII in particleassociated fractions exhibits an increased capacity for surface adhesion, transcriptional regulation and catabolism of high molecular weight substrates. Moreover, MGII populations in POM fractions are phylogenetically distinct from and more diverse than free-living MGII. Eukaryotic phytoplankton additions stimulated MGII growth in bottle incubations, providing the first MGII net growth rate measurements. These ranged from 0.47 to 0.54 d-1. However, MGII were not recovered in wholegenome amplifications of flow-sorted picoeukaryotic phytoplankton and heterotrophic nanoflagellates, suggesting that MGII in particle fractions are not physically attached to living POM. Collectively, our results support a linkage between MGII ecophysiology and POM, implying that marine archaea have a role in elemental cycling through interactions with particles. © 2015 International Society for Microbial Ecology. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
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