Evidence for direct squalene and 2,3-oxidosqualene binding by supernatant protein factor

We present the crystal structures of the SEC14-like domain of supernatant protein factor (SPF) in complex with squalene and 2,3-oxidosqualene. The structures were resolved at 1.75 Å (complex with squalene) and 1.6 Å resolution (complex with 2,3-oxidosqualene), leading in both cases to clear images of the protein/ substrate interactions. Ligand binding is facilitated by removal of the Golgi-dynamics (GOLD) C-terminal domain of SPF, which, as shown in previous structures of the apo-protein, blocked the opening of the binding pocket to the exterior. Both substrates bind into a large hydrophobic cavity, typical of such lipid-transporter family. Our structures report no specific recognition mode for the epoxide group. In fact, for both molecules, ligand affinity is dominated by hydrophobic interactions, and independent investigations by computational models or differential scanning micro-calorimetry reveal similar binding affinities for both ligands. Our findings elucidate the molecular bases of the role of SPF in sterol endo-synthesis, supporting the original hypothesis that SPF is a facilitator of substrate flow within the sterol synthetic pathway. Moreover, our results suggest that the GOLD domain acts as a regulator, as its conformational displacement must occur to favor ligand binding and release during the different synthetic steps.

Isolation, N-glycosylations and Function of a Hyaluronidase-Like Enzyme from the Venom of the Spider Cupiennius salei.

STRUCTURE OF CUPIENNIUS SALEI VENOM HYALURONIDASE Hyaluronidases are important venom components acting as spreading factor of toxic compounds. In several studies this spreading effect was tested on vertebrate tissue. However, data about the spreading activity on invertebrates, the main prey organisms of spiders, are lacking. Here, a hyaluronidase-like enzyme was isolated from the venom of the spider Cupiennius salei. The amino acid sequence of the enzyme was determined by cDNA analysis of the venom gland transcriptome and confirmed by protein analysis. Two complex N-linked glycans akin to honey bee hyaluronidase glycosylations, were identified by tandem mass spectrometry. A C-terminal EGF-like domain was identified in spider hyaluronidase using InterPro. The spider hyaluronidase-like enzyme showed maximal activity at acidic pH, between 40-60°C, and 0.2 M KCl. Divalent ions did not enhance HA degradation activity, indicating that they are not recruited for catalysis. FUNCTION OF VENOM HYALURONIDASES Besides hyaluronan, the enzyme degrades chondroitin sulfate A, whereas heparan sulfate and dermatan sulfate are not affected. The end products of hyaluronan degradation are tetramers, whereas chondroitin sulfate A is mainly degraded to hexamers. Identification of terminal N-acetylglucosamine or N-acetylgalactosamine at the reducing end of the oligomers identified the enzyme as an endo-β-N-acetyl-D-hexosaminidase hydrolase. The spreading effect of the hyaluronidase-like enzyme on invertebrate tissue was studied by coinjection of the enzyme with the Cupiennius salei main neurotoxin CsTx-1 into Drosophila flies. The enzyme significantly enhances the neurotoxic activity of CsTx-1. Comparative substrate degradation tests with hyaluronan, chondroitin sulfate A, dermatan sulfate, and heparan sulfate with venoms from 39 spider species from 21 families identified some spider families (Atypidae, Eresidae, Araneidae and Nephilidae) without activity of hyaluronidase-like enzymes. This is interpreted as a loss of this enzyme and fits quite well the current phylogenetic idea on a more isolated position of these families and can perhaps be explained by specialized prey catching techniques.

Laparoscopic Cerclage as a Treatment Option for Cervical Insufficiency

Background: The traditional surgical treatment for cervical insufficiency is vaginal placement of a cervical cerclage. However, in a small number of cases a vaginal approach is not possible. A transabdominal approach can become an option for these patients. Laparoscopic cervical cerclage is associated with good pregnancy outcomes but comes at the cost of a higher risk of serious surgical complications. The aim of the present study was to evaluate intraoperative and long-term pregnancy outcomes after laparoscopic cervical cerclage, performed either as an interval procedure or during early pregnancy, using a new device with a blunt grasper and a flexible tip. Methods: All women who underwent laparoscopic cervical cerclage for cervical insufficiency in our institution using the Goldfinger® device (Ethicon Endo Surgery, Somerville, NJ, USA) between January 2008 and March 2014 were included in the study. Data were collected from the patients' medical records and included complications during and after the above-described procedure. Results: Eighteen women were included in the study. Of these, six were pregnant at the time of laparoscopic cervical cerclage. Mean duration of surgery was 55 ± 10 minutes. No serious intraoperative or postoperative complications occurred. All patients were discharged at 2.6 ± 0.9 days after surgery. One pregnancy ended in a miscarriage at 12 weeks of gestation. All other pregnancies ended at term (> 37 weeks of gestation) with good perinatal and maternal outcomes. Summary: Performing a laparoscopic cervical cerclage using a blunt grasper device with a flexible tip does not increase intraoperative complications, particularly in early pregnancy. We believe that use of this device, which is characterized by increased maneuverability, could be an important option to avoid intraoperative complications if surgical access is limited due to the anatomical situation. However, because of the small sample size, further studies are needed to confirm our findings.

Structural studies of proteinase entrapment by human alpha 2-macroglobulin using 3-D electron microscopy

Human a2 -macroglobulin ( a2 M; homotetramer, Mr 720 kDa) is an essential scavenger of proteinases in the serum. Each of its four subunits has a ‘bait region’, with cleavage sequences for almost all endo-proteinases, an unusual thiol ester moiety and a receptor-binding domain (RBD). Bait region cleavage in native a2 M ( a2 M-N) by a proteinase results in rapid thiol ester breakage, with a large-scale structural transformation, in which a2 M uniquely entraps the proteinase in a cage-like structure and exposes receptor-binding domains for rapid endocytosis. Transformed a2 M ( a2 M-TR) contains up to two proteinases, which remain active to small substrates. 3-D electron microscopy is optimally suited to study this unusual structural change at resolutions near (1/30) Å−1. ^ The structural importance of the thiol esters was demonstrated by a genetically-engineered a2 M, with the cysteines involved in thiol ester formation mutated to serines, which appeared structurally homologous to a2 M-TR. This demonstrates that the four highly labile thiol esters alone maintain the a2 M-N structure, while the ‘closed trap’ formed by a2 M-TR is a more stable structural form. ^ Half-transformed a2 M ( a2 M-HT), with cleaved bait regions and thiol esters in only two of its four subunits, provides an important structural link between a2 M-N and a2 M-TR. A comparison with a2 M-N showed the two proteinase-entrapping domains were above and below the plane bisecting the long axis. Both a2 M-N and a2 M-TR consist of two dense, oppositely twisted strands with significant interconnections, indicating that the structural change involves a rotation of these strands. In a2 M-HT these strands were partially untwisted with large central openings, revealing the manner in which the proteinase enters the internal cavity of a2 M. ^ In reconstructions of a2 M-N, a2 M-HT and a2 M-TR labeled with a monoclonal Fab, the Fabs were located on distal ends of each constitutive strand, demonstrating an anti-parallel arrangement of the subunits. Separation between the top and bottom pairs of Fabs was nearly the same on all structures, but the pairs were rotated about the long axis. Taken together, these results indicate that upon proteinase cleavage the two strands in a2 M-N separate. The proteinase enters the structure, while the strands re-twist to encage it. In a2 M-TR, which displays receptor-binding arms, more than two subunits are transformed as strands in the transformed half of a2 M-HT were not separated. ^

Proceedings of the 14th Annual Biochemical Engineering Symposium

The Annual Biochemical Engineering Symposium series is devoted to presentations by students on their research topics. The fourteenth event, held in 1984, was organized at the University of Missouri–Columbia. It was attended by the biochemical engineering faculty and the students from Colorado State University, Iowa State University, Kansas State University, University of Missouri–Columbia, University of Missouri–Rolla and Washington University, St. Louis. Contents"Estimation of Product Formation Kinetics and Microbial Yield Parameters for Anaerobic Organic Acid and Solvent Production," M.D. Oner, Kansas State University "Characterization of Soy Protein Texturization in a Complex Bioreactor," J.L. Ibave, Colorado State University "Acid and Solvent Fermentations Using Mixed Cultures," D. Stevens, University of Missouri–Columbia "Preliminary Process Design for Ethanol from Sweet Sorghum Ensilage Feedstock," Keith D. Lange, Colorado State University "Lamella Settlers in Ethanol Fermentation," Yong Jayanata, University of Missouri–Columbia "Bubble Size Distribution in the Down Flow Section of an Air-Lift Column," Snehal A. Patel and C.H. Lee, Kansas State University "The Sensitivity of Plant Cells to Shear Stress," Morris Z. Resenberg and Eric H. Dunlap, Washington University, St. Louis "Estimation of Growth Yield Parameters Associated with Microbial Growth," Hyeon Y. Lee, Kansas State University "Capillary Gas Chromatography of Trimethylsilylated Trisaccharides," Etienne J.M. Selosse, Iowa State University "Subsite Mapping of an Endo-Xylanase Labeled Xylooligo-saccharides," Bernard Y. Tao, Iowa State University "Cellulase Enzyme Recycle," Kate M.V. Baptie, Colorado State University "Non-Homogeneous Poisson Renewal Reward Process for Modelling Enzymatic Hydrolysis of Cellulose," M.M. Gharpuray and L.T. Fan, Kansas State University

Análisis de las características antropométricas del plantel de sub 15 del Club Atlético Juventud de Las Piedras

El objetivo de este trabajo de investigación fue describir y analizar las características antropométricas del plantel sub 15 del Club Atlético Juventud de Las Piedras y relacionarlas con sus posiciones dentro del campo de juego. Para llevar adelante este estudio se tomó una muestra de 24 jugadores de entre 14 y 15 años, ésta estuvo compuesta por 1 arquero, 9 defensas, 10 volantes y 5 delanteros. Las características antropométricas descritas y analizadas fueron las 5 masas del cuerpo: masa muscular, masa de tejido adiposo, masa ósea, masa residual y piel (protocolo de Kerr y Ross), el somatotipo (protocolo de Heat y Carter), además del peso y la talla. Para llevar adelante estos protocolos se necesitó recolectar datos de pliegues, perímetros, diámetros, peso y talla. El paradigma que sustenta esta investigación es el positivista y el modelo de investigación es el cuantitativo. El nivel que alcanza este trabajo es de tipo exploratorio. El somatotipo medio del equipo fue 2,5 - 3,9 - 2,9, que corresponde a la categoría mesomorfo balanceado. Para el puesto de arquero el somatotipo fue 4,3 - 5 - 2,5, endo mesomorfico. Para los defensas 2,6 - 4,1 - 3,2, meso ectomorfico. Para los volantes 2,5 - 3,9 - 3,8, ectomorfo mesomorfo y para los delanteros 2,6 - 4,6 - 2,7, mesomorfo balanceado. El porcentaje de tejido adiposo medio del equipo fue del 29,8 , para el puesto de arquero 34,1, para los defensas 29,1, para los volantes 30,18 y para los delanteros 26,65 . El tejido muscular medio fue de 40, para el puesto de arquero 39,2, para los defensas 41,6, para los volantes 39,4 y para los delanteros 43,1. El peso y la talla media del plantel fueron 58,1 kg. Y 169,1 cm. respectivamente. Para el puesto de arquero 58,8 kg. y 165 cm., para los defensas 61,5 kg. Y 171,3 cm., para los volantes 56,4 kg. Y 169,6 cm. y por último para los delanteros 55,6 kg. Y 163,3 cm. Como conclusiones podemos afirmar que el porcentaje de masa muscular encontrado en el plantel estuvo por debajo de la media si los comparamos con equipos de igual edad de la República Argentina, no se encontraron grandes diferencias en cuanto al peso y la talla entre las distintas 3 posiciones dentro del campo de juego, a no ser por los defensas que presenta mayor estatura y mayor peso. El puesto de arquero presenta mayor porcentaje de masa grasa. Como recomendaciones finales para futuras investigaciones se proponen entre otras indagar acerca de posibles causas que influyen en el perfil antropométrico actual de los deportistas evaluados y plantear aspectos dirigidos a optimizar el mismo, realizar un perfil completo de los deportistas y llevar adelante un estudio acerca del estado nutricional de los deportistas

Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community

Little is known concerning the effect of CO2 on phytoplankton ecophysiological processes under nutrient and trace element-limited conditions, because most CO2 manipulation experiments have been conducted under elements-replete conditions. To investigate the effects of CO2 and iron availability on phytoplankton ecophysiology, we conducted an experiment in September 2009 using a phytoplankton community in the iron limited, high-nutrient, low-chlorophyll (HNLC) region of the Bering Sea basin . Carbonate chemistry was controlled by the bubbling of the several levels of CO2 concentration (180, 380, 600, and 1000 ppm) controlled air, and two iron conditions were established, one with and one without the addition of inorganic iron. We demonstrated that in the iron-limited control conditions, the specific growth rate and the maximum photochemical quantum efficiency (Fv/Fm) of photosystem (PS) II decreased with increasing CO2 levels, suggesting a further decrease in iron bioavailability under the high-CO2 conditions. In addition, biogenic silica to particulate nitrogen and biogenic silica to particulate organic carbon ratios increased from 2.65 to 3.75 and 0.39 to 0.50, respectively, with an increase in the CO2 level in the iron-limited controls. By contrast, the specific growth rate, Fv/Fm values and elemental compositions in the iron-added treatments did not change in response to the CO2 variations, indicating that the addition of iron canceled out the effect of the modulation of iron bioavailability due to the change in carbonate chemistry. Our results suggest that high-CO2 conditions can alter the biogeochemical cycling of nutrients through decreasing iron bioavailability in the iron-limited HNLC regions in the future.

Análisis de las características antropométricas del plantel de sub 15 del Club Atlético Juventud de Las Piedras

El objetivo de este trabajo de investigación fue describir y analizar las características antropométricas del plantel sub 15 del Club Atlético Juventud de Las Piedras y relacionarlas con sus posiciones dentro del campo de juego. Para llevar adelante este estudio se tomó una muestra de 24 jugadores de entre 14 y 15 años, ésta estuvo compuesta por 1 arquero, 9 defensas, 10 volantes y 5 delanteros. Las características antropométricas descritas y analizadas fueron las 5 masas del cuerpo: masa muscular, masa de tejido adiposo, masa ósea, masa residual y piel (protocolo de Kerr y Ross), el somatotipo (protocolo de Heat y Carter), además del peso y la talla. Para llevar adelante estos protocolos se necesitó recolectar datos de pliegues, perímetros, diámetros, peso y talla. El paradigma que sustenta esta investigación es el positivista y el modelo de investigación es el cuantitativo. El nivel que alcanza este trabajo es de tipo exploratorio. El somatotipo medio del equipo fue 2,5 - 3,9 - 2,9, que corresponde a la categoría mesomorfo balanceado. Para el puesto de arquero el somatotipo fue 4,3 - 5 - 2,5, endo mesomorfico. Para los defensas 2,6 - 4,1 - 3,2, meso ectomorfico. Para los volantes 2,5 - 3,9 - 3,8, ectomorfo mesomorfo y para los delanteros 2,6 - 4,6 - 2,7, mesomorfo balanceado. El porcentaje de tejido adiposo medio del equipo fue del 29,8 , para el puesto de arquero 34,1, para los defensas 29,1, para los volantes 30,18 y para los delanteros 26,65 . El tejido muscular medio fue de 40, para el puesto de arquero 39,2, para los defensas 41,6, para los volantes 39,4 y para los delanteros 43,1. El peso y la talla media del plantel fueron 58,1 kg. Y 169,1 cm. respectivamente. Para el puesto de arquero 58,8 kg. y 165 cm., para los defensas 61,5 kg. Y 171,3 cm., para los volantes 56,4 kg. Y 169,6 cm. y por último para los delanteros 55,6 kg. Y 163,3 cm. Como conclusiones podemos afirmar que el porcentaje de masa muscular encontrado en el plantel estuvo por debajo de la media si los comparamos con equipos de igual edad de la República Argentina, no se encontraron grandes diferencias en cuanto al peso y la talla entre las distintas 3 posiciones dentro del campo de juego, a no ser por los defensas que presenta mayor estatura y mayor peso. El puesto de arquero presenta mayor porcentaje de masa grasa. Como recomendaciones finales para futuras investigaciones se proponen entre otras indagar acerca de posibles causas que influyen en el perfil antropométrico actual de los deportistas evaluados y plantear aspectos dirigidos a optimizar el mismo, realizar un perfil completo de los deportistas y llevar adelante un estudio acerca del estado nutricional de los deportistas

Análisis de las características antropométricas del plantel de sub 15 del Club Atlético Juventud de Las Piedras

El objetivo de este trabajo de investigación fue describir y analizar las características antropométricas del plantel sub 15 del Club Atlético Juventud de Las Piedras y relacionarlas con sus posiciones dentro del campo de juego. Para llevar adelante este estudio se tomó una muestra de 24 jugadores de entre 14 y 15 años, ésta estuvo compuesta por 1 arquero, 9 defensas, 10 volantes y 5 delanteros. Las características antropométricas descritas y analizadas fueron las 5 masas del cuerpo: masa muscular, masa de tejido adiposo, masa ósea, masa residual y piel (protocolo de Kerr y Ross), el somatotipo (protocolo de Heat y Carter), además del peso y la talla. Para llevar adelante estos protocolos se necesitó recolectar datos de pliegues, perímetros, diámetros, peso y talla. El paradigma que sustenta esta investigación es el positivista y el modelo de investigación es el cuantitativo. El nivel que alcanza este trabajo es de tipo exploratorio. El somatotipo medio del equipo fue 2,5 - 3,9 - 2,9, que corresponde a la categoría mesomorfo balanceado. Para el puesto de arquero el somatotipo fue 4,3 - 5 - 2,5, endo mesomorfico. Para los defensas 2,6 - 4,1 - 3,2, meso ectomorfico. Para los volantes 2,5 - 3,9 - 3,8, ectomorfo mesomorfo y para los delanteros 2,6 - 4,6 - 2,7, mesomorfo balanceado. El porcentaje de tejido adiposo medio del equipo fue del 29,8 , para el puesto de arquero 34,1, para los defensas 29,1, para los volantes 30,18 y para los delanteros 26,65 . El tejido muscular medio fue de 40, para el puesto de arquero 39,2, para los defensas 41,6, para los volantes 39,4 y para los delanteros 43,1. El peso y la talla media del plantel fueron 58,1 kg. Y 169,1 cm. respectivamente. Para el puesto de arquero 58,8 kg. y 165 cm., para los defensas 61,5 kg. Y 171,3 cm., para los volantes 56,4 kg. Y 169,6 cm. y por último para los delanteros 55,6 kg. Y 163,3 cm. Como conclusiones podemos afirmar que el porcentaje de masa muscular encontrado en el plantel estuvo por debajo de la media si los comparamos con equipos de igual edad de la República Argentina, no se encontraron grandes diferencias en cuanto al peso y la talla entre las distintas 3 posiciones dentro del campo de juego, a no ser por los defensas que presenta mayor estatura y mayor peso. El puesto de arquero presenta mayor porcentaje de masa grasa. Como recomendaciones finales para futuras investigaciones se proponen entre otras indagar acerca de posibles causas que influyen en el perfil antropométrico actual de los deportistas evaluados y plantear aspectos dirigidos a optimizar el mismo, realizar un perfil completo de los deportistas y llevar adelante un estudio acerca del estado nutricional de los deportistas

X-ray fotos of 10 sediment cores from the Baltic Sea

Various types of trace fossils have been studied on radiographs of sediment cores from the Western Baltic since the early nineteen sixties. lnvestigations on the endo- und epifauna including their habitats and population densities carried out independently by biologists helped to identify the processes of their formation and classify the structures. Biogenic traces are ubiquitous in both sandy and muddy sediments of the Great Belt, where the bottom waters are weil oxygenated through inflows from the North Sea (through Kattegat-Skagerrak). Almost all types of bioturbation structures encountered in the Kiel Bay are also observed in a variety of shapes and forms, and can be considered as representative for the Western Baltic area. Polychaetes, bivalves and echinoderms were recorded at the sediment surface of the cores, and also in living positions in the sediment. The different types of burrows having distint outlines ('trace fossis'), and those having indistinct outlines ('biodeformational strctures'), and their varying abundance encountered in the area have been linked, wherever possible, to the sediment type, and to the macro-benthos.

Working on a baseline for the Kongsfjorden food web: production and properties of macroalgal particulate organic matter (POM), supplementary material

Macroalgae, in particular kelps, produce a large amount of biomass in Kongsfjorden, which is to a great extent released into the water in an annual cycle. As an example, the brown alga Alaria esculenta loses its blade gradually, 3 ± 0.8 % of the blade area per day (August 2012), thereby adding to the pool of particulate organic matter (POM) in the fjord. Upon release small thallus pieces are "aging" in that they are prone to leaching and serving as substrate for microorganisms, thus turning into palatable food for suspension and bottom feeders. In order to define a macroalgal baseline for the Kongsfjorden food web, stable isotopes d14C and d15N were measured in individuals of A. esculenta, Saccharina latissima and Laminaria digitata directly sampled after collection and in artificially produced POM (aPOM) of A. esculenta that was allowed to age under experimental conditions. In aPOM from this species sampled in August 2012 the C/N ratios decreased between d1 and d8 of a 14-day culture period in parallel to the fading photosynthetic activity of the algal fragments as demonstrated by use of an Imaging-PAM. Microscopic observations of the aPOM in August 2012 and 2013 revealed the frequent occurrence of small brown algal endo- and epiphytes. First feeding experiments with Mysis oculata (Mysids) and Hiatella arctica (Bivalves) showed that these species can ingest macroalgal POM. The importance of kelp-derived POM for the food web is subject of the current research.

Elevated CO2 affects the behavior of an ecologically and economically important coral reef fish

We tested the effect of near-future CO2 levels (= 490, 570, 700, and 960 µatm CO2) on the olfactory responses and activity levels of juvenile coral trout, Plectropomus leopardus, a piscivorous reef fish that is also one of the most important fisheries species on the Great Barrier Reef, Australia. Juvenile coral trout reared for 4 weeks at 570 µatm CO2 exhibited similar sensory responses and behaviors to juveniles reared at 490 µatm CO2 (control). In contrast, juveniles reared at 700 and 960 µatm CO2 exhibited dramatically altered sensory function and behaviors. At these higher CO2 concentrations, juveniles became attracted to the odor of potential predators, as has been observed in other reef fishes. They were more active, spent less time in shelter, ventured further from shelter, and were bolder than fish reared at 490 or 570 µatm CO2. These results demonstrate that behavioral impairment of coral trout is unlikely if pCO2 remains below 600 µatm; however, at higher levels, there are significant impacts on juvenile performance that are likely to affect survival and energy budgets, with consequences for predator-prey interactions and commercial fisheries.

(Supplement) Groundwater quality in Lahore Pakistan: emphasis on Arsenic and Fluoride levels

The dataset provides detailed information on the study that was conducted in Lahore's 7 major towns. The sample was taken from 472 tubewells and analyzed for major cations and anions using APHA 2012 techniques as explained herein. Besides, E.coli determination was done to check for microbial contamination. The data includes results from PHREEQC modeling of As(III)/ As(V) species and saturation indices as well as Aquachem's computed hydrochemical water facies. The WHO (2011) and EPA standards included in Aquachem identified the parameters that where in violation. Bicarbonates dominated the groundwater types with 50.21% of the samples exceeding the EPA maximum permissible limit of 250 mg/L in drinking water. Similarly, 30.51% of the samples had TDS values greater than 500 mg/L while 85.38 % of the samples exceed 10 µg/L threshold limit value of arsenic. Also, instances of high magnesium hazard values were observed which requires constant assessment if the groundwater is used for irrigation. Higher than 50% MH values are detrimental to crops which may reduce the expected yields. The membrane filtration technique using m-Endo Agar indicated that 3.59% samples had TNC (too numerous to count) values for E.coli while 5.06% showed values higher than 0 cfu/ 100 ml acceptable value in drinking water. Any traces of E-coli in a groundwater sample indicate recent fecal contamination. Such outcomes signify presence of enteric pathogens. If the groundwater is not properly dosed with disinfectants it may cause harm to human health. It is concluded that more studies are needed and proper groundwater management implement to safeguard the lives of communities that depend solely on groundwater in the city.

Seawater carbonate chemistry and phytoplankton and eubacterial community compositions in the northwest subarctic Pacific

On-deck CO2-Fe-manipulated incubation experiments were conducted using surface seawater collected from the Western Subarctic Gyre of the NW Pacific in the summer of 2008 to elucidate the impacts of ocean acidification and Fe enrichment on the abundance and community composition of phytoplankton and eubacteria in the study area. During the incubation, excluding the initial period, the mean partial pressures of CO2 in non-Fe-added bottles were 230, 419, 843, and 1124 µatm, whereas those in Fe-added treatments were 152, 394, 791, and 1008 µatm. Changes in the abundance and community composition of phytoplankton were estimated using HPLC pigment signatures with the program CHEMTAX and flow cytometry. A DGGE fingerprint technique targeting 16S rRNA gene fragments was also used to estimate changes in eubacterial phylotypes during incubation. The Fe addition induced diatom blooms, and subsequently stimulated the growth of heterotrophic bacteria such as Roseobacter, Phaeobacter, and Alteromonas in the post-bloom phase. In both the Fe-limited and Fe-replete treatments, concentrations of 19'-hexanoyloxyfucoxanthin, a haptophyte marker, and the cell abundance of coccolithophores decreased at higher CO2 levels (750 and 1000 ppm), whereas diatoms exhibited little response to the changes in CO2 availability. The abundances of Synechococcus and small eukaryotic phytoplankton (<10 µm) increased at the higher CO2 levels. DGGE band positions revealed that Methylobacterium of Alphaproteobacteria occurred solely at lower CO2 levels (180 and 380 ppm) during the post-bloom phase. These results suggest that increases in CO2 level could affect not only the community composition of phytoplankton but also that of eubacteria. As these microorganisms play critical roles in the biological carbon pump and microbial loop, our results indicate that the progression of ocean acidification can alter the biogeochemical processes in the study area.