ALBERT

Description: Phytoplankton productivity and community structure in the East China Sea (ECS) play an important role in marine ecology and carbon cycle, but both have been changing rapidly in response to recent oceanic and atmospheric circulation changes. However, the lack of long-term records of phytoplankton productivity and community structure variability in the region hinders our understanding of natural forcing mechanisms. Here, we use the phytoplankton biomarker (brassicasterol, dinosterol and alkenones) contents as well as the ratios between these biomarkers in three sediment cores from the ECS shelf to reconstruct the spatiotemporal variations of productivity and community of diatoms, dinoflagellates and coccolithophores during the Holocene, respectively. During 9–7 ka, the ECS shelf was characterized by low phytoplankton productivity with low coccolithophore contribution, caused by the oligotrophic condition mainly owing to the restricted Kuroshio Current (KC) intrusion under low sea-level conditions, thus the lack of nutrient input. Phytoplankton productivity generally increased during 7–4.6 ka, in response to the initial intrusion of the Yellow Sea Warm Current (YSWC, a branch of the KC), bringing nutrient from the subsurface KC to the upper layer of the ECS for phytoplankton growth. Phytoplankton productivity continuously increased during 4.6–1 ka, due to an enhanced circulation system (YSWC and Yellow Sea Coastal Current (YSCC)) driven by strong East Asia Winter Monsoon (EAWM). Significantly, high alkenone contents and coccolithophore contribution in the eastern core F11A was associated with its location closer to the warm and saline YSWC, which was suitable for coccolithophore growth. Beyond diagenetic processes which could partly account for higher biomarker contents near core tops, elevated phytoplankton productivity during the last 1 ka might be induced by more nutrient supply from the intensified circulation system driven by enhanced KC and anthropogenic activities. The latter also resulted in high dinoflagellate proportions in all three cores. These temporal and spatial changes of phytoplankton productivity and community structure in the ECS during the Holocene corresponded to different mechanisms by the air-sea interaction, providing insights into distinguishing natural forcing and anthropogenic influences on marine ecology.

Description: In this study, organic geochemical analyses of two sediment cores (BL16 and LV63–23) recovered from the western Bering Sea were carried out to examine the sea-ice variability and its relationship to phytoplankton community evolution over the past century. Bulk stable organic carbon isotopic composition (δ13CTOC) showed pronounced depletion on the northern shelf since the late 1970s, indicating greater terrigenous organic matter (OM) under warming during recent decades. Variation in sedimentary OM in the southward core was closely associated with marine primary productivity and regional deposition processes. Arctic sea-ice proxy IP25 throughout the two cores with different temporal profile patterns demonstrated sea-ice presence with the spatiotemporal variability across the study area over the past century. The phytoplankton marker-IP25 index (PIP25), a proxy for estimating semi-quantitatively sea-ice concentrations, reflected a decreased sea-ice cover with more distinct interannual fluctuations between 0.7 and 0.2 (especially in core BL16) after the late 1970s, coinciding with the recent warming scenario. Increased concentrations of phytoplankton biomarkers (brassicasterol and dinosterol) and their ratios as well as the PIP25 record in core BL16 indicated a synchronous variability of reduced sea-ice cover with the enhancement of phytoplankton productivity since the late 1970s. These results suggested a coupled interaction of the sea-ice condition and planktonic ecosystem in the north Bering shelf. Our results also revealed recent (since the 2000s) spatial heterogeneity in sea-ice coverage between the northern and southern parts of the Bering Sea.

Description: Millennial scale variations of terrigenous provenance in marine realm are closely related to regional environment and climate changes. Therefore, a wealth of information of past environment and climate can be constrained via fingerprinting sediment provenance. The Sea of Japan is a unique marginal sea in the North Pacific due to its high sill and distinct thermohaline circulation. The modern hydrography in the Sea of Japan is mainly affected by the East Asian Monsoon and Tsushima Warm Current, one branch of the Kuroshio Current. The Sea of Japan communicates with neighboring seas through four shallow and narrow straits, indicating great effects of global eustatic sea level change on its environment over glacial-interglacial cycles. Here we examine the terrigenous provenance in fine-grained fraction (〈63 μm) of core KCES1, located near one end of the Tsushima Strait of the Sea of Japan over the last 48 ka, using radiogenic isotopes of strontium (Sr) and neodymium (Nd). Our data suggest that the terrigenous provenance in core KCES1 was mainly derived from the Yangtze River after 7 ka and a mixture of Yangtze and Yellow Rivers during the last glacial and deglacial periods. Notably, pronounced negative excursions of εNd values at HS1 were attributed to minor additions of unradiogenic Nd contribution from China-Korea cratonic hinterland. A binary mixing model further reveals that 〉85% terrigenous material is derived from the Yangtze and Yellow Rivers over the last 48 ka. Moreover, abrupt variations in sediment provenance occurred at ~18 ka and ~ 7 ka, which coincide with variations in oceanic surface circulation and deep ventilation recorded in the Sea of Japan. We suggest that paleo-Tsushima Warm Current invaded into the Sea of Japan with reopening of the Tsushima Strait at HS1 and the Tsushima Warm Current substantially entered the Sea of Japan after 7 ka due to intensified Kuroshio Current and rising eustatic sea level. The inflow of Tsushima Warm Current gives rise to a range of changes in surface hydrography, deep ventilation, ecological communities and productivity and sediment texture. The combination of fluxes of paleo-rivers and the intensity of Kuroshio Current, which are closely tied to the eustatic sea level and the East Asian Monsoon, plays a key role in controlling the variations in sediment provenance in the Ulleung Basin. Our study provides unique insight into the tight coupling between changes in sediment provenance and oceanic environment over the last 48 ka in the Sea of Japan.

Description: The Kuroshio Current (KC) is the northward branch of the North Pacific subtropical gyre (NPG) and exerts influence on the exchange of physical, chemical, and biological properties of downstream regions in the Pacific Ocean. Resolving long-term changes in the flow of the KC water masses is, therefore, crucial for advancing our understanding of the Pacific's role in global ocean and climate variability. Here, we reconstruct changes in KC dynamics over the past 20 ka based on grain-size spectra, clay mineral, and Sr–Nd isotope constraints of sediments from the northern Okinawa Trough. Combined with published sediment records surrounding the NPG, we suggest that the KC remained in the Okinawa Trough throughout the Last Glacial Maximum. Together with Earth-System-Model simulations, our results additionally indicate that KC intensified considerably during the early Holocene (EH). The synchronous establishment of the KC “water barrier” and the modern circulation pattern during the EH highstand shaped the sediment transport patterns. This is ascribed to the precession-induced increase in the occurrence of La Niña-like state and the strength of the East Asian summer monsoon. The synchronicity of the shifts in the intensity of the KC, Kuroshio extension, and El Niño/La Niña-Southern Oscillation (ENSO) variability may further indicate that the western branch of the NPG has been subject to basin-scale changes in wind stress curl over the North Pacific in response to low-latitude insolation. Superimposed on this long-term trend are high-amplitude, large century, and millennial-scale variations during last 5 ka, which are ascribed to the advent of modern ENSO when the equatorial oceans experienced stronger insolation during the boreal winter.

Description: Major shifts in ocean circulation are thought to be responsible for abrupt changes in temperature and atmospheric CO2 during the last deglaciation, linked to variability in meridional heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2 rise, including enhanced diatom production in regions such as the tropical Atlantic. However, it remains unclear as to whether this diatom production was driven by enhanced wind-driven upwelling or density-driven vertical mixing, or by elevated thermocline concentrations of silicic acid supplied to the surface at a constant rate. Here, we demonstrate that silicic acid supply at depth in the NE Atlantic was enhanced during the abrupt climate events of the deglaciation. We use marine sediment archives to show that an increase in diatom production during abrupt climate shifts could only occur in regions of the NE Atlantic where the deep supply of silicic acid could reach the surface. The associated changes are indicative of enhanced regional wind-driven upwelling and/or weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced thermocline concentrations of silicic acid suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling.

Description: Abstract 4886 Detection of high molecular weight light chain oligomers in urinary exosomes of patients with AL amyloidosis. Background Exosomes are microvesicles that are part of the multivesicular body (MVB) pathway. They are created by the inward budding of the cell surface membrane and contain both surface bound membrane proteins and cytosolic proteins which can be used to identify the cell of origin. Immunoglobulin light chain amyloidosis (AL) occurs as the result of amyloid formation by the misfolding of monoclonal light chains (LC) and deposition of these amyloid fibrils in various soft tissues. This reaction requires the organization of the monoclonal LC's into protofibrils which are then weave into amyloid fibrils. This study was undertaken to determine whether urinary exosomes of glomerular origin contain intermediate species of amyloid formation. Method Urine samples from patients with AL, light chain deposition disease (LCDD), multiple myeloma (MM) and monoclonal clonal gammopathy of undetermined significance (MGUS) were collected. Urinary exosomes were isolated and separated into fractions by gradient centrifugation. Western blots were performed on the urinary exosome fractions using anti-kappa or anti-lambda antibodies. Glomerular fractions were identified using antibodies directed toward podocin. Results Urine samples were collected from 5 patients with AL, 2 from LCDD, 1 from MM and 1 MGUS. On the Western blot, immunoglobulin LC were seen in all exosomal fractions in patients with AL amyloidosis, LCDD, MM but not MGUS which is similar to normal controls (not shown). In patients with AL, oligomeric species were found in the highest concentrations in fraction 4 and 5 (Figure 1). Fraction 4 and 5 were also stained for podocin, a glomerular protein (not shown). The highest molecular weight species was ∼250 kd which corresponds to a LC decamer. High molecular weight species were also identified in 1 of 2 LCDD patients corresponding to a tetramer. The band was identified in fraction 10 which had polycystin-1 expression suggesting a tubular origin. No high molecular weight LC species was found in patients with MM or MGUS. Conclusion Our study found high molecular weight LC species corresponding to the intermediates involved in protofibril formation in urinary exosomes of patients with AL. Smaller (tetramer) high molecular weight LC species were also found in a patient with LCDD but not in patients with MM and MGUS. Not only were the high molecular weight LC species found exclusively in the diseases characterized by deposition of LC aggregates, they were also found in the segments of the nephron where the deposits were expected: glomerulus for AL and tubular epithelium for LCDD. This is consistent with our current understanding of the pathogenic mechanisms of these diseases. We believe urinary exosomes are a powerful tool in the study of diseases involving self-aggregation of monoclonal proteins. It has tremendous potential in both diagnostic and scientific research in this area. Disclosures Gertz: celgene: Honoraria; millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Description: Chromosomal translocations (CTs) between immunoglobulin (Ig) genes and the BCL6 proto-oncogene are frequently associated with diffuse large B-cell lymphomas (DLBCLs) and follicular lymphomas (FLs) and are implicated in the development of these lymphomas. However, whether Ig/BCL6 translocation per se is sufficient to drive malignant transformation is not clear. To understand the biology of Ig/BCL6-translocated cells prior to their malignant transformation, we developed a system capable of detecting 1 to 3 Igμ/BCL6 CT cells in 1 million mixed cells through the detection of chimeric Iμ-BCL6E2 and BCL6E1-Cμ1 transcripts that reflect reciprocal Igμ/BCL6 translocations. The chimeric transcripts that existed in the vast majority of normal lymphoid tissues are due to Igμ/BCL6 CT and were not generated from trans-splicing. Both Iμ-BCL6E2 and BCL6E1-Cμ1 transcripts were coexpressed in the same cell populations. The Ig/BCL6 recombination junctions themselves were isolated from B-cell subpopulations expressing the Iμ-BCL6 transcripts. The appearance of Igμ/BCL6 CT was associated with cells expressing germinal center but not naive B-cell markers. This study shows that Ig/BCL6 translocations occur in germinal center–stage B cells in healthy humans, and that Ig/BCL6 CTs per se are not likely sufficient to cause the malignant transformation in the context of human B cells.

Description: VEGF induces vascular permeability (VP) in ischemic diseases and cancer, leading to many pathophysiological consequences. The molecular mechanisms by which VEGF acts to induce hyperpermeability are poorly understood and in vivo models that easily facilitate real-time, genetic studies of VP do not exist. In the present study, we report a heat-inducible VEGF transgenic zebrafish (Danio rerio) model through which VP can be monitored in real time. Using this approach with morpholino-mediated gene knock-down and knockout mice, we describe a novel role of phospholipase Cβ3 as a negative regulator of VEGF-mediated VP by regulating intracellular Ca2+ release. Our results suggest an important effect of PLCβ3 on VP and provide a new model with which to identify genetic regulators of VP crucial to several disease processes.