The dynamic changes of stable isotopic ratios of carbon and nitrogen in suspended and sedimented particulate organic matter during a phytoplankton bloom

The dynamic changes of carbon and nitrogen stable isotopic ratios in suspended and sedimented particulate matter were observed together with many other chemical and biological properties during a phytoplankton bloom induced by nutrient addition in a controlled ecosystem enclosure (CEE, about 70 m3) in Saanich Inlet, British Columbia, Canada. Both of the stable isotopic ratios of carbon (δ13C) and nitrogen (δ15N) in suspended particulate organic matter showed characteristic patterns of variations in surface water during the bloom. The δ13C of suspended particulate matter increased with the growth of phytoplankton population and decreased gradually after the depletion of NO3− and NO2−. The δ15N of suspended particulate matter was very low soon after the beginning of phytoplankton bloom, but the value increased rapidly with the decrease in NO3− and NO2−, and reached maximal value following nutrient depletion, after which the δ15N remained high until the end of the experiment. In order to understand such variations of δ13C and δ15N, we made the mass and isotopic balance models of carbon and nitrogen for the upper layer of the CEE, and simulated the temporal variations of δ13C and δ15N of particulate organic matter using them in connection with several hypotheses on the isotope fractionations associated with the uptake of inorganic substrates by phytoplankton. While neither change in the dissolved inorganic carbon (i.e., its isotope ratio and/or molecular CO2 concentration) nor the phytoplankton species compositions can well explain the variation of δ13C, this variation can be well simulated considering the effect of change in the specific production rate of particulate organic carbon. On the other hand, the variations of δ15N can be clearly understood by a first-order isotope fractionation model under the assumption of large isotopic fractionation during the assimilation of NO3− and NO2− by phytoplankton. The particulate organic matter produced in the nutrient controlled phytoplankton bloom can be classified into three phases from an isotopic viewpoint: (I) the early stage of the phytoplankton bloom when NO3− plus NO2− were still in excess in sea water (high δ13C but low δ15N), (II) the late stage of the bloom when NO3− plus NO2− had just been depicted (high δ13C and high δ15N) and (III) the steady state phase, a few days after the depletion of NO3− plus NO2− (low δ13C but high δ15N). The cooperative variation of δ13C and δ15N in the suspended and sedimented particulate organic matter was also demonstrated

Postazacitidine clone size predicts long-term outcome of patients with myelodysplastic syndromes and related myeloid neoplasms

Azacitidine is a mainstay of therapy for MDS-related diseases. The purpose of our study is to elucidate the effect of gene mutations on hematological response and overall survival (OS), particularly focusing on their post-treatment clone size. We enrolled a total of 449 patients with MDS or related myeloid neoplasms. They were analyzed for gene mutations in pre- (n=449) and post- (n=289) treatment bone marrow samples using targeted-capture sequencing to assess the impact of gene mutations and their post-treatment clone size on treatment outcomes. In Cox proportional hazard modeling, multi-hit TP53 mutation (HR, 2.03; 95% CI, 1.42-2.91; P<.001), EZH2 mutation (HR, 1.71; 95% CI, 1.14-2.54; P=.009), and DDX41 mutations (HR, 0.33; 95% CI, 0.17-0.62; P<.001), together with age, high-risk karyotypes, low platelet, and high blast counts, independently predicted OS. Post-treatment clone size accounting for all drivers significantly correlated with International Working Group (IWG)-response (P<.001, trend test), except for that of DDX41-mutated clones, which did not predict IWG-response. Combined, IWG-response and post-treatment clone size further improved the prediction of the original model and even that of a recently proposed molecular prediction model, IPSS-M (c-index, 0.653 vs 0.688; P<.001, likelihood ratio test). In conclusion, evaluation of post-treatment clone size, together with pre-treatment mutational profile as well as IWG-response have a role in better prognostication of azacitidine-treated myelodysplasia patients

The Physics of the B Factories

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C

Source of organic matter in the sinking particles collected from the Pacific Sector of the Antarctic Ocean by sediment trap experiment

Sediment trap experiment was conducted at Stn. 3 (61°34.1′S, 150°23.3′E) in the Pacific Sector of the Antarctic Ocean for 23 days from December 20,1983 to January 13,1984. Sinking particles from 630,1430 and 3230m depths, suspended particles from 1,30,80 and 500m depths and bottom sediment were analyzed for hydrocarbons, which consisted of n-alkanes with the carbon atoms ranging from 14 to 32 (n-alkane, n-C_-C_), heneicosahexaene (n-C_), isoprenoid hydrocarbons and branched C_ and cyclic C_ alkenes (br-C_ and c-C_). Hydrocarbons were quantified by gas chromatography and identified and/or elucidated by combined gas chromatography and mass spectrometry. Isoprenoid hydrocarbons consisted of squalene, pristane and phytane, while branched C_ and C_ alkenes were composed of br-C_, br-C_, br-C_ (isomer of br-C_), c-C_ and c-C_. Hydrocarbon composition was characteristic to each of the particle and sediment samples. Thus, the hydrocarbon composition gives us a clue to clarify the source of organic matter in the sinking particles collected from the intermediate and deep waters. Heneicosahexaene widely occurring in diatoms and coccolithophores, was found in the suspended and sinking particles, indicating that organic matter in the sinking particles was derived from diatoms and/or coccolithophores living in the surface waters. br-C_ and C_ alkenes commonly found in the fecal pellets, were abundant in the sinking particles collected from the intermediate through deep waters. Thus, these findings indicate that large part of the organic materials in the sinking particles are derived from phytoplankton growing in the surface waters through fecal pellets of zooplankton. Occurrence of br-C_ and C_ alkenes even in the suspended particles of the euphotic layers indicates that these particles are contaminated by zooplankton fecal pellets and/or their debris. Further discussions will be conducted on the source materials of the sinking particles on the basis of the hydrocarbon compositions of the suspended and sinking particles

Organic compounds of the suspended particles in the Pacific Sector of the Southern Ocean

Particulate matter was collected from the ocean areas of the West Pacific and the Pacific Sector of the Antarctic Ocean (32°N-65°S, 125°-160°E) during the cruise of T. S. UMITAKA MARU of Tokyo University of Fisheries in 1980-1981. The samples were analyzed for organic carbon and nitrogen, carbohydrate, amino acids including free and combined forms, lipid and chlorophylls. Detailed analyses of fatty acids of the particulate samples were conducted to clarify their ecological significance in the Antarctic Ocean. Characteristic features of particulate organic matter in the Antarctic Ocean are as follows. 1) Particulate organic carbon (POC) and nitrogen (PON) collected from the surface waters of the western Pacific and Antarctic Oceans were determined as the ranges of 25.4-150μgC/l and 3.50-25.2μgC/l respectively. POC and PON are distributed with relatively low values in the western Pacific Ocean, while much higher level of the values was observed in the Antarctic Ocean. Regional variabilities of the values occurred to a great extent. 2) Particulate matter collected from the Antarctic Ocean was analyzed for carbohydrate, amino acid and lipid, which accounted for 18.6-40.3%, 11.1-16.5% and 22.7-37.8% of POC respectively. Lipid materials were much abundant in the particulate matter collected from the oceanic area south of the Antarctic Divergence. 3) Fatty acids with carbon atoms ranging from 14 to 24 were detected in the particulate matter from the Antarctic Ocean and were quantified by gas chromatography. The ratio of unsaturated fatty acids with carbon atoms of 16,18 and 20 to total fatty acids tended to increase toward Antarctica. These unsaturated fatty acids accounted for more than 40% of total fatty acids of the particulate matter from the oceanic area south of the Antarctic Divergence. 4) Fecal pellet of Euphausia superba and its feed, Dunaliella tertiolecta were analyzed for fatty acids to elucidate their ecological significance in the Antarctic Ocean. The results obtained indicated that algal fatty acids and amino acids were digested exclusively by the zooplankton. Unsaturated fatty acids with carbon atoms of 16 and 18 accounted for more than 80% of total loss of the fatty acids during the digestion processes of algal organic matter by the zooplankton. These findings strongly suggested that unsaturated fatty acids must be one of the most ecologically significant organic materials in the Antarctic Ocean

Distribution of particulate organic materials in the Pacific and Indian Sectors of the Antarctic Ocean in the austral summer

Particulate matter was collected from the surface through deep water layers at 31 hydrographic stations along the four transects in the Pacific sector and one transect in the Indian sector of the Antarctic Ocean. The particulate matter was analyzed for organic carbon (POC), amino acid, carbohydrate and lipid contents. The Pacific sector was divided into three water masses, each of which was subdivided into three water layers. The average POC concentrations among the three water masses ranged from 55.6 to 82.0μgC/l in the surface water layer (0-100m), the value tending to decrease with depth to 24.5-47.1 and 19.2-40.4μgC/l in the intermediate (125-200m) and deep (300-1500m) water layers, respectively. The values are lower than those reported in the most productive oceanic areas, but higher than those reported in low latitude areas and comparable to those reported in middle latitude areas in the Pacific and Atlantic Oceans. Along the transect in the Indian sector, the average POC concentration was 237μgC/l in the surface water layer. This high concentration of POC was assumed to give rise to the spring phytoplankton blooming in this region. The percentages of amino acid-, carbohydrate- and lipid-carbons in POC were determined. The percentages of amino acid- and lipid-carbons in POC increased southward to the areas where the dichothermal water was observed. Significantly high percentages of amino acid-carbon in POC were found for the particulate matter suspended in the water layer above the cold water mass. On the other hand, high values for the particulate lipid were obtained in and below the cold water mass. It was concluded that the protein-rich particulate matter was distributed in the water layer above the cold water mass, while lipid-rich particulate matter was localized in the cold water mass. The high concentration of the glycolipid and relatively low concentrations of both the simple lipid and the phospholipid were characteristics of the particulate matter suspended in the dichothermal water. Mechanisms of these characteristic distributions of the particulate amino acid and lipid were discussed