Automated enumeration by computer digitization of age-0 weakfish Cynoscion regalis scale circuli

There has been extensive use of daily otolith growth increments in age and growth ·studies of age-O fishes (Campana and Neilson 1985). Recently, the daily ageing method has been extended to scales (Szedlmayer et al. In press). However, visually counting increments is tedious, time consuming, and subject to human error (Rice 1987). In an effort to automate the counting of increments or daily circuli in scales of age-O juvenile weakfish Cynoscion regalis, a microcomputer-based system was used to digitize the video image of a scale, store the light intensities from a radial transect, and count circuli

Aerobic anoxygenic phototrophic bacteria and their roles in marine ecosystems

Aerobic anoxygenic phototrophic bacteria (AAPB) are characterized by the following physiological and ecological features. A mother AAPB cell can unusually divide into 3 daughter cells and looks like a "Y" during the division. AAPB cells sometimes adhere together forming a free-floating population. Most of the known AAPB species are obligately aerobic. Bacteriochlorophyll a (BChl a) is the only photosynthetic pigment in AAPB, and the number of BChl a molecules in an AAPB cell is much less than that in an anaerobic phototrophic bacterial cell, while the accessorial pigments carotenoids in AAPB are abundant in concentration and diverse in species. In addition to the common magnesium containing BChl a, a zinc-containing BChla was also seen in AAPB. AAPB have light harvesting complex I but usually lack light harvesting complex II. Although AAPB featur in photosynthesis, their growth is not necessarily light-dependent. There is a mechanism controlling the photosynthesis approach. AAPB are widely distributed in marine environments especially in oligotrophic oceans accounting for a substantial portion of the total biomass and playing a unique role in the cycle of carbon and other biogenic elements. Besides the contribution to primary production, AAPB also have great potentials in bioremediation of polluted environments. Studies on AAPB would be of great value in understanding the evolution of photosynthesis and the structure and function of marine ecosystems

Small-volume potentiometric titrations: EPR investigations of Fe-S cluster N2 in mitochondrial complex

EPR-based potentiometric titrations are a well-established method for determining the reduction potentials of cofactors in large and complex proteins with at least one EPR-active state. However, such titrations require large amounts of protein. Here, we report a new method that requires an order of magnitude less protein than previously described methods, and that provides EPR samples suitable for measurements at both X- and Q-band microwave frequencies. We demonstrate our method by determining the reduction potential of the terminal [4Fe-4S] cluster (N2) in the intramolecular electron-transfer relay in mammalian respiratory complex I. The value determined by our method, Em7 = − 158 mV, is precise, reproducible, and consistent with previously reported values. Our small-volume potentiometric titration method will facilitate detailed investigations of EPR-active centres in non-abundant and refractory proteins that can only be prepared in small quantities

RAPID : research on automated plankton identification

Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 2 (2007): 172-187.When Victor Hensen deployed the first true plankton1 net in 1887, he and his colleagues were attempting to answer three fundamental questions: What planktonic organisms are present in the ocean? How many of each type are present? How does the plankton’s composition change over time? Although answering these questions has remained a central goal of oceanographers, the sophisticated tools available to enumerate planktonic organisms today offer capabilities that Hensen probably could never have imagined.This material is based upon work supported by the National Science Foundation under Grants OCE-0325018, OCE-0324937, OCE-0325167 and OCE-9423471, and the European Union under grants Q5CR-2002-71699, MAS3-ct98-0188, and MAS2-ct92-0015

Capturing Single Cell Genomes of Active Polysaccharide Degraders: An Unexpected Contribution of Verrucomicrobia

Microbial hydrolysis of polysaccharides is critical to ecosystem functioning and is of great interest in diverse biotechnological applications, such as biofuel production and bioremediation. Here we demonstrate the use of a new, efficient approach to recover genomes of active polysaccharide degraders from natural, complex microbial assemblages, using a combination of fluorescently labeled substrates, fluorescence-activated cell sorting, and single cell genomics. We employed this approach to analyze freshwater and coastal bacterioplankton for degraders of laminarin and xylan, two of the most abundant storage and structural polysaccharides in nature. Our results suggest that a few phylotypes of Verrucomicrobia make a considerable contribution to polysaccharide degradation, although they constituted only a minor fraction of the total microbial community. Genomic sequencing of five cells, representing the most predominant, polysaccharide-active Verrucomicrobia phylotype, revealed significant enrichment in genes encoding a wide spectrum of glycoside hydrolases, sulfatases, peptidases, carbohydrate lyases and esterases, confirming that these organisms were well equipped for the hydrolysis of diverse polysaccharides. Remarkably, this enrichment was on average higher than in the sequenced representatives of Bacteroidetes, which are frequently regarded as highly efficient biopolymer degraders. These findings shed light on the ecological roles of uncultured Verrucomicrobia and suggest specific taxa as promising bioprospecting targets. The employed method offers a powerful tool to rapidly identify and recover discrete genomes of active players in polysaccharide degradation, without the need for cultivation

Analysis of apparent optical properties and ocean color models using measurements of seawater constituents in New England continental shelf surface waters

Author Posting. © American Geophysical Union, 2004. 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 109 (2004): C03026, doi:10.1029/2003JC001977.We used budgets of absorption (a), scattering (b), and backscattering (bb) for particles and chromophoric dissolved organic matter (CDOM) to investigate sources of seasonal variations in apparent optical properties (AOPs) of New England continental shelf surface waters. Spectral a, b, and bb budgets for particles were estimated from flow cytometric measurements of eukaryotic pico/nanophytoplankton, Synechococcus, heterotrophic prokaryotes, detritus, and minerals; AOPs were modeled with Hydrolight radiative transfer software. For late summer and spring, our modeled values of the diffuse attenuation coefficient (Kd) and remote sensing reflectance (Rrs) were on average within 15% and 9%, respectively, of independent measurements. This close agreement allowed us to examine how different seawater constituents contributed to AOP variability. Higher values of Kd in the spring, compared to summer, were due to higher absorption by eukaryotic phytoplankton (aeuk) and CDOM (aCDOM), which coincided with higher nutrient levels and less stratified conditions than in the summer. Differences in the spectral shape of Rrs between the seasons were caused by a combination of differences in aeuk, aCDOM, and bb from non-phytoplankton particles (minerals and detritus combined). For non-phytoplankton bb the major seasonal difference was a higher inverse wavelength dependence in the summer due to the effects of small organic detritus. We applied two semianalytical ocean color models to our data, in order to evaluate whether the assumptions and parameterizations inherent in these models are applicable for New England shelf waters. We show how differences between observed and modeled chlorophyll a specific phytoplankton absorption, aCDOM, and non-phytoplankton bb cause errors in chlorophyll a concentration and IOPs retrieved from reflectance inversion models.Financial support was provided by ONR grants N00014-95-1-0333 and N00014-96-1-0965 (H. Sosik and R. Olson), NASA grants NAGW- 517, NAG5-7538, and NAG5-8868, and a NASA Earth System Science Fellowship (R. Green)

Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition

A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems