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N -methyl-D-aspartate receptor (NMDAR) encephalitis is the most common subtype of autoimmune encephalitis characterized by a complex neuropsychiatric syndrome usually including memory impairment. Patients develop an intrathecal immune response against NMDARs with antibodies that presumably bind to the amino-terminal domain of the GluN1 subunit. The therapeutic response to immunotherapy is often delayed. Therefore, new therapeutic approaches for fast neutralization of NMDAR antibodies are needed. Here, we developed fusion constructs consisting of the Fc part of immunoglobulin G and the amino-terminal domains of either GluN1 or combinations of GluN1 with GluN2A or GluN2B. Surprisingly, both GluN1 and GluN2 subunits were required to generate high-affinity epitopes. The construct with both subunits efficiently prevented NMDAR binding of patient-derived monoclonal antibodies and of patient CSF containing high-titre NMDAR antibodies. Furthermore, it inhibited the internalization of NMDARs in rodent dissociated neurons and human induced pluripotent stem cell-derived neurons. Finally, the construct stabilized NMDAR currents recorded in rodent neurons and rescued memory defects in passive-transfer mouse models using intrahippocampal injections. Our results demonstrate that both GluN1 and GluN2B subunits contribute to the main immunogenic region of the NMDAR and provide a promising strategy for fast and specific treatment of NMDAR encephalitis, which could complement immunotherapy. [ABSTRACT FROM AUTHOR]

Burkholderia encompasses a group of ubiquitous Gram-negative bacteria that includes numerous saprophytes as well as species that cause infections in animals, immunocompromised patients, and plants. Some species of Burkholderia produce colored, redox-active secondary metabolites called phenazines. Phenazines contribute to competitiveness, biofilm formation, and virulence in the opportunistic pathogen Pseudomonas aeruginosa, but knowledge of their diversity, biosynthesis, and biological functions in Burkholderia is lacking. In this study, we screened publicly accessible genome sequence databases and identified phenazine biosynthesis genes in multiple strains of the Burkholderia cepacia complex, some isolates of the B. pseudomallei clade, and the plant pathogen B. glumae. We then focused on B. lata ATCC 17760 to reveal the organization and function of genes involved in the production of dimethyl 4,9-dihydroxy-1,6-phenazinedicarboxylate. Using a combination of isogenic mutants and plasmids carrying different segments of the phz locus, we characterized three novel genes involved in the modification of the phenazine tricycle. Our functional studies revealed a connection between the presence and amount of phenazines and the dynamics of biofilm growth in flow cell and static experimental systems but at the same time failed to link the production of phenazines with the capacity of Burkholderia to kill fruit flies and rot onions. [ABSTRACT FROM AUTHOR]

Upper water column dynamics in the eastern Arabian Sea were reconstructed in order to investigate changes in the activity of the South Asian / Indian monsoon during the early Pleistocene (c. 1.5–2.7 Ma). We used planktic foraminiferal assemblage records combined with isotopic (δ18O and δ13C) data, Mg/Ca-based sea surface temperatures and seawater δ18O records to estimate changes in surface water conditions at International Ocean Discovery Program (IODP) Site U1457. Our records indicate two distinct regimes of monsoon-induced changes in upper water structure during the periods c. 1.55–1.65 Ma and c. 1.85–2.7 Ma. We infer that a more stratified upper water column and oligotrophic mixed layer conditions prevailed during the period 1.85–2.7 Ma, which may be due to overall weaker South Asian / Indian winter (NE) and summer (SW) monsoon circulations. The period 1.55–1.65 Ma was characterized by enhanced eutrophication of the mixed layer, which was probably triggered by intensified winter (NE) monsoonal winds. The long-term trend in hydrographic changes during 1.55–1.65 Ma appears to be superimposed by short-term variations, probably reflecting glacial/interglacial changes. We suggest that an intensification of the South Asian / Indian winter monsoon circulation occurred between ∼1.65 Ma and 1.85 Ma, which is most likely due to the development of strong meridional and zonal atmospheric circulations (i.e. Walker Circulation and Hadley Circulation) because of strong equatorial East–West Pacific temperature gradients. [ABSTRACT FROM AUTHOR]

Sediment depositional patterns along the upper continental slope of the northern South China Sea (SCS) have been studied using two sediment cores (GeoB16601-6, 20°09.07'N, 116°14.38'E, 1012 m water depth and GeoB16602-4, 18°57.12'N, 113°42.64'E, 951 m water depth) recovered during RV SONNE Cruise SO-221 "INVERS". Sediment cores were analyzed for bulk sediment element composition by X-Ray Fluorescence (XRF) core scanning and clay mineral assemblage by X-Ray Diffraction (XRD). The bulk sediment element and the clay mineral compositions of the two cores suggest similar depositional patterns between 50 kyr BP and ~29 kyr BP, and ~14 kyr BP to present, but a clear difference in depositional patterns during the last glacial and deglacial (~29-14 kyr BP) when sea level was below-90 m. Between ~29-14 kyr BP, a higher kaolinite percentage in core GeoB16602-4 in comparison to core GeoB16601-6 is interpreted to reflect a higher contribution of clay supplied by the Pearl River to core site GeoB16602-4. In contrast, core GeoB16601-6 received less Pearl River supplied clayeymaterial during the same period. When the sea levelwas below-90mduring the last glacial lowstand, the detrital fine-grained materials supplied by the Pearl River were mostly transported by coastal currents to the southwest, resulting in a higher contribution of Pearl River discharged material at site GeoB16602-4 than at site GeoB16601-6. We suggest that sea-level induced modifications of the land-ocean distribution together with changes in the palaeo-physiographic conditions, such as the proximity of the palaeo-rivers to the individual core sites might be responsible for the different sediment depositional patterns in the study area. Thus, the overriding control of sea-level induced changes on the sediment depositional environment might mask climate-related changes in sediment depositional pattern in the northern SCS. [ABSTRACT FROM AUTHOR]

Abstract: The Australian–Indonesian monsoon has a governing influence on the agricultural practices and livelihood in the highly populated islands of Indonesia. However, little is known about the factors that have influenced past monsoon activity in southern Indonesia. Here, we present a ∼6000 years high-resolution record of Australian-Indonesian summer monsoon (AISM) rainfall variations based on bulk sediment element analysis in a sediment archive retrieved offshore northwest Sumba Island (Indonesia). The record suggests lower riverine detrital supply and hence weaker AISM rainfall between 6000 yr BP and ∼3000 yr BP compared to the Late Holocene. We find a distinct shift in terrigenous sediment supply at around 2800 yr BP indicating a reorganization of the AISM from a drier Mid Holocene to a wetter Late Holocene in southern Indonesia. The abrupt increase in rainfall at around 2800 yr BP coincides with a grand solar minimum. An increase in southern Indonesian rainfall in response to a solar minimum is consistent with climate model simulations that provide a possible explanation of the underlying mechanism responsible for the monsoonal shift. We conclude that variations in solar activity play a significant role in monsoonal rainfall variability at multi-decadal and longer timescales. The combined effect of orbital and solar forcing explains important details in the temporal evolution of AISM rainfall during the last 6000 years. By contrast, we find neither evidence for volcanic forcing of AISM variability nor for a control by long-term variations in the El Niño-Southern Oscillation (ENSO). [Copyright &y& Elsevier]

Abstract: We use new and published data to discuss the East Asian winter monsoon (EAWM) development and the relationship between the EAWM and the East Asian summer monsoon (EASM) since the Last Glacial Maximum (LGM) with special emphasis on the Holocene. The depth of the mixed layer in the northern South China Sea (SCS) is strongly modulated by the seasonal reversing monsoon winds with deeper vertical mixing during the winter monsoon season and less mixing during the summer monsoon season. Reconstructing the relative depth of the mixed layer thus represents a sensitive diagnostic variable of past changes in the EAWM strength. We derived estimates of the vertical thermal structure from the difference (∆T) in Mg/Ca-based temperatures between surface- (Globigerinoides ruber) and thermocline-dwelling (Pulleniatina obliquiloculata) planktonic foraminifera, and the temperature difference between alkenone and P. obliquiloculata in core MD05-2904 located in the northern SCS. Our ∆T estimates suggest enhanced upper water column mixing due to strengthened EAWM winds during the last glacial, consistent with other marine and terrestrial records as well as model simulations that also suggest a dominance of the cold and dry northwesterly winter monsoon system during the last glacial. Our ∆T estimates reveal that the EAWM was weaker during the Holocene compared to the last glacial. We find that EAWM and EASM changes show an inverse behaviour during the last glacial that is consistent with previous studies but co-varied during the Holocene. It can be inferred from these findings that the variability of the East Asian monsoon during the Holocene is more complex than the simple anti-phase relationship between summer and winter monsoon as assumed previously. The early-mid Holocene strengthening of both the EAWM and the EASM is most likely attributed to the higher summer insolation that resulted in a stronger seasonal contrast. [Copyright &y& Elsevier]

Abstract: The present study is the first study on the stable oxygen isotope composition of the photosynthetic calcareous-walled dinoflagellate species Thoracosphaera heimii off NW Africa during the last 45,000yr. T. heimii based temperature estimates of sediment core GeoB 8507-3 were compared with those obtained from the stable oxygen isotopes of the planktic foraminifera Globigerina bulloides and Globigerinoides ruber (pink), and the Mg/Ca ratio of G. ruber (pink). We show that the isotopic composition of T. heimii and the temperature estimates based on the equation for inorganically precipitated calcite provide comparable results to those obtained from G. ruber (pink) isotopes and Mg/Ca ratios with exception of the Early Holocene and the Younger Dryas. The recently proposed palaeotemperature equation of Zonneveld et al. (2007), however, provides unrealistic temperature reconstructions that are about 16°C lower than those based on planktic foraminifera. Thus, this equation needs to be revised. The difference between T. heimii and G. bulloides isotopic and temperature reconstructions can be ascribed to differences in the ecology of both species, especially with regard to their depth habitat and/or seasonal production in the research area. All temperature proxies suggest comparable conditions during the last glacial and Holocene. Small differences between the reconstructed temperature values of T. heimii and the other proxies can be explained by differences in seasonal production of the individual species. The relatively low temperatures recorded by T. heimii at about 15,000 to 8,000yr BP are interpreted to reflect an increase in duration and/or intensity of the upwelling in the vicinity of the core site in comparison to the last glacial, with an abrupt and strong decrease of upwelling intensity and/or duration during the Early Holocene and the Younger Dryas. [Copyright &y& Elsevier]

Abstract: The monsoon system represents one of the basic elements of global atmospheric circulation. Its evolution and variability over long periods of geologic time play a significant role in our understanding of global climate. In this study, we focus on the Late Miocene interval from 10Ma to 6Ma, a period of postulated profound ecological and environmental shifts in East and South Asia. The combined approach of measuring planktonic foraminiferal Mg/Ca ratios and stable oxygen isotopes from Ocean Drilling Program (ODP) Site 1146 enabled us to reconstruct temperature independent seawater δ 18O (i.e. proxy for sea surface salinity) variations in order to reconstruct the hydrography in the northern South China Sea. Located offshore the Pearl (Zhujiang) River, or its predecessor, the location of ODP Site 1146 is considered to provide a most sensitive record for detecting potential changes in freshwater input/river run-off as a result of changes in continental humidity, and hence changes in East Asian summer monsoon (EASM) climate. Local seawater δ 18O reconstructions reveal that monsoon development during the Late Miocene can be regarded as an abrupt weakening in the EASM around 7.5Ma. We suggest that an EASM weakening was most likely the driving force for decreasing aridity in East and South Asia at 8–6Ma, leading to widespread ecosystem changes in East and South Asia. [Copyright &y& Elsevier]

Abstract: Quantifying the spatial and temporal sea surface temperature (SST) and salinity changes of the Indo-Pacific Warm Pool is essential to understand the role of this region in connection with abrupt climate changes particularly during the last deglaciation. In this study we reconstruct SST and seawater δ 18O of the tropical eastern Indian Ocean for the past 40,000years from two sediment cores (GeoB 10029-4, 1°30′S, 100°08′E, and GeoB 10038-4, 5°56′S, 103°15′E) retrieved offshore Sumatra. Our results show that annual mean SSTs increased about 2–3°C at 19,000years ago and exhibited southern hemisphere-like timing and pattern during the last deglaciation. Our SST records together with other Mg/Ca-based SST reconstructions around Indonesia do not track the monsoon variation since the last glacial period, as recorded by terrestrial monsoon archives. However, the spatial SST heterogeneity might be a result of changing monsoon intensity that shifts either the annual mean SSTs or the seasonality of G. ruber towards the warmer or the cooler season at different locations. Seawater δ 18O reconstructions north of the equator suggest fresher surface conditions during the last glacial and track the northern high-latitude climate change during the last deglaciation. In contrast, seawater δ 18O records south of the equator do not show a significant difference between the last glacial period and the Holocene, and lack Bølling-Allerød and Younger Dryas periods suggestive of additional controls on annual mean surface hydrology in this part of the Indo-Pacific Warm Pool. [Copyright &y& Elsevier]

Abstract: Variations in clay mineral composition of sediment cores from the margin and continental slope of the Sunda Shelf (southern South China Sea, SE Asia) covering the past 17,000 yr reflect changing influences of sediment sources together with clay mineral partitioning processes in shallow waters. We identify the deglacial sea level rise as the principal factor driving these changes. During the late glacial, high values of kaolinite are interpreted to reflect a higher contribution of clays from soils that have formed on the exposed Sunda Shelf and in the southern archipelagos of Indonesia. At this time core sites were located in close proximity to the mouths of the Sunda Shelf palaeo-drainage systems on the emerged shelf (“Sundaland”). The progressive landward displacement of the coastline and breakdown of these vast drainage systems during deglaciation led to a decrease in influence of the kaolinite-rich southern sources. When the coastline had retreated closely to its present-day position in mid-Holocene times, the former dominance of southern sources was replaced by a stronger influence of illite-rich sources (e.g. Borneo). The overriding control of sea level changes on the clay mineral distribution patterns precludes a definite climatic interpretation of clay mineral data in terms of climatic/monsoonal changes in such highly dynamic sedimentary environment. [Copyright &y& Elsevier]

Abstract: Sea surface temperatures (SSTs), reconstructed from two Globigerinoides ruber (white) morphotypes (G. ruber sensu stricto, (s.s.); G. ruber sensu lato, ( s.l.)) Mg/Ca and alkenones (UK′ 37) from core MD01-2390 from the tropical South China Sea (SCS) during the last deglaciation reveal a proxy-dependent discrepancy in the temporal pattern of the deglacial warming. Alkenone data suggest that the deglacial warming is punctuated by a decrease in temperature between ∼17 and 15ka BP, corroborating previously published alkenone UK′ 37 SST records from the southern SCS. Within dating uncertainties, this cooling is coeval with the Heinrich Event 1 (H1) time interval in the North Atlantic region, underscoring the imprints of northern hemisphere forcing on tropical SCS ocean temperatures. The deglacial UK′ 37 SST minimum is also paralleled by a maximum in G. ruber morphotype-specific δ18O. G. ruber Mg/Ca SST estimates suggest a morphotype-specific record of SSTs during the time interval of H1. Whereas G. ruber s.s. imply a continuous warming starting around 18ka BP without any marked response to H1, G. ruber s.l.-based Mg/Ca SST estimates reveal a cooling around ∼17–15ka BP similar to the H1 interval cooling seen in the alkenone SST record. Similar proxy-dependent differences in deglacial surface water warming have been recorded in the eastern equatorial Pacific, implying a common pattern on both sides of the tropical Pacific Ocean. We submit that this discrepancy could be due to differences in seasonality of planktonic foraminifera G. ruber morphotypes and alkenone-producing algae. [Copyright &y& Elsevier]

Abstract: Sea-surface temperature (SST) estimates in the sediment core MD01-2390 based on planktonic foraminiferal species abundances using five different transfer function techniques suggest nearly unchanged or unusually higher temperatures in the tropical southern South China Sea (SCS) during the Last Glacial Maximum (LGM) relative to modern temperatures. These results are in contrast to substantial cooling of 2–5 °C inferred by geochemical (Uk'' 37, Mg/Ca ratios) and terrestrial proxies from the western tropical Pacific region. Using multivariate statistics we show that the glacial southern SCS harboured unique planktonic foraminiferal assemblages that have no modern analogs. Analyses of faunal variation through the core reveal that planktonic foraminiferal assemblages responded to temperature changes inferred from Mg/Ca data but that this signal is subdued by superimposed variations in the relative abundance of Pulleniatina obliquiloculata and Neogloboquadrina pachyderma (dextral). These species occur in glacial samples at proportions that are not observed in the calibration data set. The glacial high abundance of N. pachyderma (dextral) are interpreted to reflect a seasonal (winter) inflow of cold surface water from the northeast via the Bashi Strait due to the combined effects of an intensified winter monsoon, a southward shift of the polar front and the eastward migration of the Kuroshio Current. In contrast, processes controlling the high relative abundances of P. obliquiloculata during the LGM may be unique to the southern SCS. We propose a scenario involving a stronger (winter) mixing or enhanced upwelling due to an intensified winter monsoon that prevented shallow-dwelling, warm indicators to establish larger populations during the LGM. Our results indicate that a no-analog behaviour of planktonic foraminifera faunas is responsible for the warm glacial conditions in this part of the western Pacific warm pool as implied by foraminiferal transfer functions and that a more significant surface cooling in the region as implied by terrestrial and geochemical (Mg/Ca ratios; alkenone unsaturation index) marine proxies is a more likely scenario. [Copyright &y& Elsevier]

Abstract: Changes in the local freshwater budget over the last 22,000 years have been estimated from a sediment core located in the southern South China Sea (SCS) using a combined approach of Mg/Ca and oxygen isotopes on the planktonic foraminifera Globigerinoides ruber (white) sensu stricto (s.s.). Core MD01-2390 (06°28,12N, 113°24,56E; water depth 1591m) is located near the glacial paleo-river mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers that drained the exposed Sunda Shelf. The δ 18Oseawater record reveals lower average values (−0.96±0.18‰) during the Last Glacial Maximum (LGM) when compared with modern values (−0.54±0.18‰). Low salinity during the LGM is interpreted to reflect a higher freshwater contribution due to a greater proximity of the core site to the mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers at that time. A general deglacial increasing trend in salinity due to the progressive landward displacement of the coastline during deglacial shelf flooding is punctuated by several short-term shifts towards higher and lower salinity that are likely related to abrupt changes in the intensity of the East Asian summer monsoon. Thus, the deglacial δ 18Oseawater changes reflect the combined effects of sea-level-induced environmental changes on the shelf (e.g. phases of retreat and breakdown of the shelf drainage systems) and East Asian monsoon climate change. Lower salinity than at present during the Early Holocene may be attributed to an increase in summer monsoonal precipitation that is corroborated by previous marine and terrestrial studies that report a Preboreal-Early Holocene monsoon optimum in the Asian monsoon region. [Copyright &y& Elsevier]

Deglacial sedimentation on the outer Sunda Shelf, the shelf margin and slope shows a close correlation with the stages of flooding of the emerged shelf. It is mainly controlled by the relationship between shelf paleo-physiography and changes in sea level and sediment supply. Based on the sedimentological and geochemical variability at five sites along a transect across the outer shelf and the continental slope covering the last 20 000 years, four intervals of significant depositional changes are identified. The first reorganization in the sedimentation regime, which was established during sea-level lowstand, is associated with the drowning of the lower course of the North Sunda River between 16.5 and 14.5 ka. During and following the rapid rise in sea level at 14.5–14 ka, sedimentation on the slope is characterized by an accelerated decrease in the supply of terrigenous material, associated with the flooding of the middle part of the paleo-valley. This abrupt change in sedimentation is followed by a period of gradual decrease of terrigenous supply to the slope, when the surrounding plains of the river valley were flooded (14–8.5 ka). The final change occurred between ca. 8.5 and 6 ka, when the coastline reached its modern position, and modern sedimentary patterns are established. This change probably marks the end of reworking by transgression. Given the synchroneity of sedimentological changes along the transect across the Sunda Shelf and into the deep sea with the environmental shifts on the central shelf, sedimentation on the margin and slope appears to be mainly controlled by the interrelationship of sea level, shelf paleo-physiography and sediment supply. Moreover, the records display lateral changes through time associated with stages of the deglacial transgression, which mask any potential sedimentological variability due to changes in precipitation, vegetation or atmospheric circulation. This fact cautions the interpretation of near-shore sedimentary records as unequivocal recorders of local climate change (e.g. SE Asian monsoon), and highlights the need to include variations in shelf physiography and sea level in future paleoceanographic studies. [Copyright &y& Elsevier]

Background: The COVID-19 pandemic is caused by the betacoronavirus SARS-CoV-2. In November 2021, the Omicron variant was discovered and immediately classified as a variant of concern (VOC), since it shows substantially more mutations in the spike protein than any previous variant, especially in the receptor-binding domain (RBD). We analyzed the binding of the Omicron RBD to the human angiotensin-converting enzyme-2 receptor (ACE2) and the ability of human sera from COVID-19 patients or vaccinees in comparison to Wuhan, Beta, or Delta RBD variants.Methods: All RBDs were produced in insect cells. RBD binding to ACE2 was analyzed by ELISA and microscale thermophoresis (MST). Similarly, sera from 27 COVID-19 patients, 81 vaccinated individuals, and 34 booster recipients were titrated by ELISA on RBDs from the original Wuhan strain, Beta, Delta, and Omicron VOCs. In addition, the neutralization efficacy of authentic SARS-CoV-2 wild type (D614G), Delta, and Omicron by sera from 2× or 3× BNT162b2-vaccinated persons was analyzed.Results: Surprisingly, the Omicron RBD showed a somewhat weaker binding to ACE2 compared to Beta and Delta, arguing that improved ACE2 binding is not a likely driver of Omicron evolution. Serum antibody titers were significantly lower against Omicron RBD compared to the original Wuhan strain. A 2.6× reduction in Omicron RBD binding was observed for serum of 2× BNT162b2-vaccinated persons. Neutralization of Omicron SARS-CoV-2 was completely diminished in our setup.Conclusion: These results indicate an immune escape focused on neutralizing antibodies. Nevertheless, a boost vaccination increased the level of anti-RBD antibodies against Omicron, and neutralization of authentic Omicron SARS-CoV-2 was at least partially restored. This study adds evidence that current vaccination protocols may be less efficient against the Omicron variant. [ABSTRACT FROM AUTHOR]

The integrated effects of the Western Pacific Warm Pool (WPWP) and the Kuroshio Current (KC) on the thermal evolution of the subtropical northwestern Pacific during the Holocene have remained elusive. This study presents new δ18O and Mg/Ca ratio records of subsurface-dwelling planktonic foraminifera Pulleniatina obliquiloculata at Site A7 in the Okinawa Trough to reconstruct thermocline-water evolution since the last deglaciation (∼18 ka) and further explore the effects of the WPWP and the KC dynamics throughout the Holocene. The Mg/Ca-based thermocline-water temperature (TWT) record displays a long-term cooling trend of ∼3 °C since the middle Holocene (∼7 ka), with a similar trend with that in the WPWP. Furthermore, two major thermocline warming events occurred with an amplitude of ∼2–3 °C in the early (∼11.8–9.5 ka) and middle (∼8–6.5 ka) Holocene, respectively. Both events are comparable with those in the WPWP. Besides, our TWT record had nine Holocene rapid cooling events with amplitudes of ∼1–2 °C around 1.7, 3.2, 4.4, 6.0, 7.2, 7.5, 8.2, 8.9, and 10 ka, respectively. The cooling events were also identified in the temperature records of the thermocline and/or intermediate waters in the WPWP within the chronological uncertainties. The comparability of these temperature records between both regions reveals that the dynamic KC transmitted thermal signals of the WPWP thermocline/intermediate waters into the Okinawa Trough on centennial to multi-millennial timescales, highlighting a crucial role of the WPWP in influencing subtropical ocean thermodynamics and climate in the Holocene. • Thermocline temperature record was reconstructed in the Okinawa Trough since 18 ka. • A mid- to late Holocene thermocline cooling trend and two major EH & MH thermocline warming events in the Okinawa Trough. • Thermal signals of the WPWP were transmitted by the KC on centennial to multi-millennial timescales in the Holocene. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) and seawater δ 18 O sw records were generated from sediment cores located in the southern Bay of Bengal (SBOB) and the northeastern Arabian Sea (NEAS) to understand glacial to Holocene changes in the hydrography of these regions. This was accomplished through the use of paired δ 18 O and Mg/Ca measurements in planktic foraminifera ( Globigerinoides ruber ) from two sediment cores; SK157-14 in the SBOB (lat. 5°11′N; long. 90°05′E; water-depth 3306 m) and SK148-21 in the NEAS (lat. 21°29′N, long. 67°01′E; water-depth 1900 m). The results suggest significant changes in SST and δ 18 O sw since last glacial period. The glacial SSTs in the SBOB and the NEAS were lower by ~ 2–2.5 °C relative to the Holocene. The deglacial period in both cores is characterized by significant variations in SSTs and seawater δ 18 O sw . The Dansgaard-Oeschger (DO) cycles and Heinrich events are strongly expressed in SST and δ 18 O sw records of the SBOB core. These records support a strong control of atmospheric-oceanic changes in the northern high latitude on thermal state of the SBOB. The SST time series in both these regions indicates a sudden and abrupt increase in temperature at the end of last glacial maximum. The SST time series in the NEAS core SK 148-21 reveals an intensification of the northeast monsoon during the last glacial maximum. [ABSTRACT FROM AUTHOR]

The East Australian Current (EAC) is the western boundary current of the South Pacific Subtropical Gyre that transports warm tropical waters to higher southern latitudes and significantly impacts the climate of Australia and New Zealand. Modern observations show that the EAC has strengthened with rising global temperatures. However, little is known about the pre‐industrial variability of the EAC and the forcing mechanisms. Planktic foraminifera Globigerinoides ruber (white) Mg/Ca‐based sea surface temperature reconstructions offshore northeastern Australia between 15° and 26°S reveal an increase by ∼1.2°C after ∼1400 CE. We infer that the increase in temperature is related to a stronger EAC heat transport that is likely driven by a strengthening of the Southern Hemisphere subtropical gyre circulation due to a progressive shift of the Southern annular mode toward its positive phase and of El Niño‐Southern Oscillation toward more El Niño‐like conditions. Plain Language Summary: The East Australian Current (EAC) transports large amounts of heat out of the Western Pacific Warm Pool into the subtropics and subpolar regions, thereby regulating the local and global climate. The few existing reconstructions of past changes in transport and temperature of the EAC are contradictory resulting in a knowledge gap in long‐term variability of the southwest Pacific currents, which in turn hampers a reliable projection of future tropical and subtropical climate development. We use sea surface temperature reconstructions along the EAC path off northeastern Australia to estimate changes in the EAC heat transport over the past 4,000 years and its potential driving mechanisms. Our results reveal an increase in temperature after ∼1400 CE, which we relate to an intensification of the EAC strength. The strengthening of the EAC after ∼1400 CE is likely associated with a strengthening of the Southern Hemisphere subtropical gyre circulation due to a progressive shift of the Southern annular mode toward its positive phase and of El Niño‐Southern Oscillation toward more El Niño‐like conditions. Key Points: Mg/Ca‐based sea surface temperature reconstructions reveal an intensification of the East Australian Current (EAC) after ∼1400 CEA stronger EAC is likely driven by strengthening of the Southern Hemisphere subtropical gyre due to a Southern Annular Mode shift toward its positive phaseMore El Niño‐like conditions may also strengthen the EAC by an equatorward shift of the South Equatorial Current bifurcation latitude [ABSTRACT FROM AUTHOR]

Global atmospheric circulation experienced drastic changes during the Middle Miocene climate transition (MMCT∼14.7–13.0 Ma) possibly related to the glaciation on West-Antarctica. Palaeoceanographic reconstructions have found that upwelling in the western Arabian Sea due to summer South Asian monsoon (SAM) winds likely occurred since ∼14.7 Ma, with fully modern-like monsoonal wind patterns after the end of the MMCT at around ∼13 Ma. Whether the changes in monsoonal circulation since ∼14.7 Ma are also associated with upper ocean hydrographic changes in the eastern Arabian Sea (EAS) is currently not known for the middle Miocene. To this end, the difference in Mg/Ca-based temperatures (ΔT°C) of surface-dwelling with lower mixed layer/thermocline-dwelling and sub-thermocline-dwelling planktic foraminifera was reconstructed to estimate the upper ocean thermal gradient at Site NGHP-01-01 A in the EAS and thus changes in the upper surface water column structure, i.e., mixed layer depth (MLD) and the depth of thermocline (DOT). The Mg/Ca-temperature estimates from the upper mixed layer down to the sub-thermocline show a prominent cooling trend between ∼14.2 Ma and 13.2 Ma. The upper water column reconstructions reveal weaker mixing, a shallower thermocline, and therefore a well stratified upper water column in the EAS after ∼14.2 Ma. We suggest that the weaker mixing and shallower thermocline in the EAS after ∼14.2 Ma are most likely due to an intensification of the summer SAM. A strong salinity stratification and/or the formation of a barrier layer (BL) because of increased SAM rainfall and advection of low salinity water may also have contributed to a weaker mixing and shallower thermocline in the EAS during the investigated time period. The change in the upper ocean hydrography in the EAS after ∼14.2 Ma fits well into the emerging picture of monsoonal-driven upper ocean hydrographic changes in the equatorial and northern Indian Ocean due to an intensification of the summer SAM since ∼14.7 Ma. • Cooling of the mixed layer and sub-thermocline in the eastern Arabian Sea (EAS) between ∼14.2 Ma and 13.2 Ma • Weaker mixing, a shallower thermocline, and a well stratified upper water column occurred in the EAS after ∼14.2 Ma • A shallower thermocline in the EAS after ∼14.2 Ma is most likely due to an intensification of the summer SAM • A strong salinity stratification due to stronger summer SAM rainfall may also have contributed to a shallower thermocline • Results support monsoonal-driven hydrographic changes in the Arabian Sea due to an intensified summer SAM since ∼14.7 Ma [ABSTRACT FROM AUTHOR]

The development of antibody therapies against SARS-CoV-2 remains a challenging task during the ongoing COVID-19 pandemic. All approved therapeutic antibodies are directed against the receptor binding domain (RBD) of the spike, and therefore lose neutralization efficacy against emerging SARS-CoV-2 variants, which frequently mutate in the RBD region. Previously, phage display has been used to identify epitopes of antibody responses against several diseases. Such epitopes have been applied to design vaccines or neutralize antibodies. Here, we constructed an ORFeome phage display library for the SARS-CoV-2 genome. Open reading frames (ORFs) representing the SARS-CoV-2 genome were displayed on the surface of phage particles in order to identify enriched immunogenic epitopes from COVID-19 patients. Library quality was assessed by both NGS and epitope mapping of a monoclonal antibody with a known binding site. The most prominent epitope captured represented parts of the fusion peptide (FP) of the spike. It is associated with the cell entry mechanism of SARS-CoV-2 into the host cell; the serine protease TMPRSS2 cleaves the spike within this sequence. Blocking this mechanism could be a potential target for non-RBD binding therapeutic anti-SARS-CoV-2 antibodies. As mutations within the FP amino acid sequence have been rather rare among SARS-CoV-2 variants so far, this may provide an advantage in the fight against future virus variants. [ABSTRACT FROM AUTHOR]

SUMMARY: Food allergies are a major health issue worldwide. Modern breeding techniques such as genome editing via CRISPR/Cas9 have the potential to mitigate this by targeting allergens in plants. This study addressed the major allergen Bra j I, a seed storage protein of the 2S albumin class, in the allotetraploid brown mustard (Brassica juncea). Cotyledon explants of an Indian gene bank accession (CR2664) and the German variety Terratop were transformed using Agrobacterium tumefaciens harboring binary vectors with multiple single guide RNAs to induce either large deletions or frameshift mutations in both Bra j I homoeologs. A total of 49 T0 lines were obtained with up to 3.8% transformation efficiency. Four lines had large deletions of 566 up to 790 bp in the Bra j IB allele. Among 18 Terratop T0 lines, nine carried indels in the targeted regions. From 16 analyzed CR2664 T0 lines, 14 held indels and three had all four Bra j I alleles mutated. The majority of the CRISPR/Cas9‐induced mutations were heritable to T1 progenies. In some edited lines, seed formation and viability were reduced and seeds showed a precocious development of the embryo leading to a rupture of the testa already in the siliques. Immunoblotting using newly developed Bra j I‐specific antibodies revealed the amount of Bra j I protein to be reduced or absent in seed extracts of selected lines. Removing an allergenic determinant from mustard is an important first step towards the development of safer food crops. Significance Statement: Mustard is a significant elicitor of allergic reactions to food. The major allergen in brown mustard (Brassica juncea) is Bra j I, a 2S albumin seed storage protein. This is the first report of genome editing in B. juncea, and we mutated up to all four gene copies in this tetraploid plant resulting in plants with reduced levels or absence of Bra j I protein. [ABSTRACT FROM AUTHOR]

• Succession from offshore archives to distinguish pollen signature of salt marshes. • Wetland expansions at Pearl River estuary closely linked with rapid sea-level rises. • Palaeoecological data suggest resilience of coastal wetlands to sea-level rises. • Marine pollen records may indicate the long-term coastal wetlands history. The response of coastal wetlands to future sea-level rise remains uncertain. Palaeoecological data are essential to constrain the still conflicting ecological models. However, obtaining detailed palaeo-coastal stratigraphic records before Holocene is often difficult due to repeated Quaternary marine transgression-regressions. Here we utilize pollen data from a deep-sea sedimentary archive in northern South China Sea to explore the historical behavior of coastal wetlands at a large river estuary over the last 140-kyr. A recurrent wetland (Cyperaceae)-pioneer species (Selaginella)-zonal forest (Pinus) succession throughout the last glacial-interglacial cycle implies a coastal salt marsh origin of the Cyperaceae pollen. Comparing with global sea-level reconstructions, the increases in Cyperaceae pollen abundance, and hence the expansions of coastal salt marsh, were found to be closely linked with rapid large-scale sea-level rises. This finding indicates a resilience of coastal wetlands to future sea-level rise, and highlights the probable importance of conventionally ignored horizontal adaptability in long-term survival of coastal wetlands. Overall, marine pollen records provide an opportunity to supplement existing palaeoecological observations of coastal wetlands during the Quaternary. [ABSTRACT FROM AUTHOR]

Abstract: Millennial-scale variations of the East Asian winter monsoon (EAWM) remain elusive due to sparse and controversial reconstructions. By compiling a variety of alkenone-based sea surface temperature (SST) estimates, we find that the west–east SST gradient in the southern South China Sea (SCS) well documents the temporal dynamics of the winter “cold tongue” off the southern Vietnam and by inference, variations in the EAWM intensity over the past 26ka. Our results reveal that the winter “cold tongue” SSTs were significantly colder during Heinrich event 1 and the Younger Dryas event, resulting in an increased west–east SST gradient in the southern SCS due to a strengthened EAWM. Within dating uncertainties, an intensified EAWM during cold stadials was coeval with the shutdown or a reduction in strength of the Atlantic meridional overturning circulation (AMOC), exhibiting a strong linkage between the AMOC and the EAWM system. The west–east SST gradient also indicates an enhanced EAWM during the early Holocene, which may be induced by postglacial ice-sheet dynamics and a strong seasonal contrast in solar insolation. Our findings suggest that the EAWM was probably modulated by a complex interplay between the AMOC, solar insolation and ice-sheet dynamics on sub-orbital time scales. [ABSTRACT FROM AUTHOR]

Abstract: The Late Pliocene is thought to be characterized by the simultaneous intensification of both the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM). However, the evolution of the EASM during the Pliocene remains still controversial and only little is known about the dynamics of the EASM during the Pliocene on orbital time scales. Here we use clay mineral assemblages in sediments from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea (SCS) to obtain proxy records of past changes in the EASM climate during the Pliocene. Provenance analysis suggests that illite, chlorite and kaolinite originated mainly from the Mekong River drainage area. Smectite was derived mainly from the Indonesian islands. The kaolinite/illite ratio and the chemical index of alteration (CIA) of siliciclastic sediments allowed us to reconstruct the history of chemical weathering and physical erosion of the Mekong River drainage area and thus, the evolution of the EASM during the Pliocene. Our clay minerals proxy data suggests a stronger EASM during the Early Pliocene than during the Late Pliocene. We propose that the long-term evolution of the EASM has been driven by global cooling rather than the uplift of the Tibetan Plateau. Spectral analysis of kaolinite/illite ratio displays a set of strong periodicities at 100ka, 30ka, 28ka, 25ka, and 22ka, with no clear obliquity-related signal. Our study suggests that the Pliocene EASM intensity on orbital time scales is not only controlled by the Northern Hemisphere summer insolation, but also strongly influenced by equatorial Pacific ENSO-like ocean–atmosphere dynamics. [Copyright &y& Elsevier]

Abstract: Surface and thermocline conditions of the eastern tropical Indian Ocean were reconstructed through the past glacial–interglacial cycle by using Mg/Ca and alkenone-paleothermometry, stable oxygen isotopes of calcite and seawater, and terrigenous fraction performed on sediment core GeoB 10038-4 off SW Sumatra (∼6°S, 103°E, 1819m water depth). Results show that annual mean surface and thermocline temperatures varied differently and independently, and suggest that surface temperatures have been responding to southern high-latitude climate, whereas the more variable thermocline temperatures were remotely controlled by changes in the thermocline temperatures of the North Indian Ocean. Except for glacial terminations, salinity proxies indicate that changing intensities of the boreal summer monsoon did not considerably affect annual mean conditions off Sumatra during the past 133,000years. Our results do not show a glacial–interglacial pattern in the thermocline conditions and reject a linear response of the tropical Indian Ocean thermocline to mid- and high-latitude climate change. Alkenone-based surface temperature estimates varied in line with the terrigenous fraction of the sediment and the East Asian winter monsoon proxy records at the precession band suggestive of monsoon (sea level) to be the dominant control on alkenone temperatures in the eastern tropical Indian Ocean on sub-orbital (glacial–interglacial) timescales. [Copyright &y& Elsevier]

The integrated effects of ocean‐atmosphere dynamics on the temperature evolution in the western North Pacific marginal seas have remained elusive. In order to study mechanisms controlling southern Yellow Sea (YS) temperature changes, bottom water temperature (BWT) changes were reconstructed for the last 8.8 kyr by using the TEXL86 index, which archives temperature signal of the winter season Yellow Sea Warm Current. Our results reveal a series of abrupt multi‐centennial to millennial scale BWT changes (∼1°C), superimposed on a gradual long‐term cooling (>3°C) trend starting from ∼5 ka to the present. The YS BWT changes are positively correlated with subsurface water temperature changes in the Western Pacific Warm Pool (WPWP). The Western Pacific Warm Pool subsurface water cooling signal was most likely transmitted by the Kuroshio Current into the southern YS, highlighting the role of WPWP in influencing thermodynamics of the extratropical regions during the Holocene. Plain Language Summary: The Yellow Sea (YS) is a semi‐closed marginal sea located in the northwestern Pacific Ocean. During the winter season, the Yellow Sea Warm Current (YSWC) is driven by northwesterly winds, flowing into the southern YS along the west flank of the central trough. The YSWC, a continuation of the Kuroshio Current, brings warm equatorial Pacific water into the YS, leading to milder winters in the surrounding coastal cities compared with other cities on the same latitude in China. The YSWC is sensitive to changes in ocean‐atmosphere dynamics. However, its evolution during the Holocene is not well understood. We reconstruct the winter season temperature changes of the YSWC during the last 8.8 kyr. We found warm temperatures during the mid‐Holocene (8.8‐5 ka) and a gradual cooling trend over the last 5 kyr, which coincides with subsurface water temperature changes in the Western Pacific Warm Pool (WPWP). We suggest that the tropical subsurface water temperature changes of the WPWP are most likely transmitted via the Kuroshio Current into the YS. Our results shed new light on our understanding of the role played by the WPWP water masses in regulating subtropical ocean dynamics and climate during the mid‐to‐late Holocene. Key Points: The temperature evolution of the winter season Yellow Sea Warm Current was reconstructed over the past 8.8 kyrAbrupt multi‐centennial to millennial scale changes are superimposed on a gradual cooling trend starting from ∼5 ka to the presentWestern Pacific Warm Pool subsurface water cooling signal was transmitted by the Kuroshio Current into the southern Yellow Sea [ABSTRACT FROM AUTHOR]

Pteropods are marine holoplanktonic gastropods inhabiting epipelagic and mesopelagic waters with a wide distribution from tropical to polar regions. However, their ontogeny and calcification depth/habitat depth are not well understood. To this end, we analyzed the stable oxygen isotopic composition of five pteropod species (Diacavolinia angulata , Diacavolinia longirostris , Heliconoides inflatus , Limacina bulimoides and Telodiacria quadridentata) from two multicores recovered offshore north-eastern Australia between 15°S and 26°S in the Coral Sea. We applied the Limacina dissolution index (LDX) to evaluate the preservation status of the pteropods, which revealed very good to moderate aragonite preservation at both locations. Comparison of the pteropod shell oxygen isotopic composition with predicted aragonite equilibrium oxygen isotope values implies calcification depths of 50 ± 20 m for D. longirostris and 75 ± 30 m for D. angulata , suggesting that they predominantly calcify in the mixed layer during austral summer. The apparent calcification depths of T. quadridentata and H. inflatus at 90 ± 30 m and 120 ± 30 m at both sites indicate a year-round, lower mixed layer and upper thermocline habitat depth, respectively, while T. quadridentata appear to calcify at temperatures above 22 °C. The calcification depth of L. bulimoides is deeper (100 ± 15 m) at the northern station and shallower (75 ± 30 m) at the southern station that might also hint to a temperature control. The relative narrow calcification depth ranges of the investigated pteropod species in the Coral Sea bolster their potential for reconstructing past ocean conditions at the mixed layer and thermocline. • Calcification depth estimates of five pteropod species in the Coral Sea using shell stable oxygen isotopes • Moderate to good preservation of pteropod shells in the Coral Sea • D. angulata and D. longirostris calcify within the mixed layer in the Coral Sea • H. inflatus and L. bulimoides calcify within the thermocline • T. quadridentata has a more variable habitat depth, ranging from the mixed layer to the lower thermocline [ABSTRACT FROM AUTHOR]

Antibodies are essential tools for therapy and diagnostics. Yet, production remains expensive as it is mostly done in mammalian expression systems. As most therapeutic IgG require mammalian glycosylation to interact with the human immune system, other expression systems are rarely used for production. However, for neutralizing antibodies that are not required to activate the human immune system as well as antibodies used in diagnostics, a cheaper production system would be advantageous. In our study, we show cost-efficient, easy and high yield production of antibodies as well as various secreted antigens including Interleukins and SARS-CoV-2 related proteins in a baculovirus-free insect cell expression system. To improve yields, we optimized the expression vector, media and feeding strategies. In addition, we showed the feasibility of lyophilization of the insect cell produced antibodies. Furthermore, stability and activity of the antibodies was compared to antibodies produced by Expi293F cells revealing a lower aggregation of antibodies originating from High Five cell production. Finally, the newly established High Five expression system was compared to the Expi293F mammalian expression system in regard of yield and costs. Most interestingly, all tested proteins were producible in our High Five cell expression system what was not the case in the Expi293F system, hinting that the High Five cell system is especially suited to produce difficult-to-express target proteins. [ABSTRACT FROM AUTHOR]

A 1108.6 m long core was recovered at Site U1457 located on the Indus Fan in the Laxmi Basin of the eastern Arabian Sea during IODP Expedition 355. Shipboard examinations defined five lithologic units (I to V) of the lower Paleocene to Holocene sedimentary sequence. In this study, δ13C values of sedimentary organic matter (SOM) confirm the differentiation of the lithologic units and further divide units III and IV into two subunits (1 and 2). Based on the underlying assumption that the SOM is decided primarily by a mixture of marine and terrestrial origins, δ13CSOM values at Site U1457 provide information on the terrestrial catchment conditions since late Miocene time. Low δ13CSOM values from late Miocene to late Pleistocene times are similar (c. −22.0 ‰) for the most part, reflecting a consistent contribution of terrestrial organic matter from the catchment areas characterized by dominant C3 land plants. Significantly lower δ13CSOM values (c. −24.0 ‰) in Unit III-2 (∼8 to ∼7 Ma) might be due to a greater input of C3 terrestrial organic matter. The increase in δ13CSOM values at ∼7 Ma and the appearance of high δ13CSOM values (c. −18.0 ‰) within Unit III-1 (∼7 to ∼2 Ma) indicate that C4 biomass overwhelmed the terrestrial catchment environment as a result of enhanced terrestrial aridity in the Himalayan foreland. The three-end-member simple mixing model, estimating the relative contributions of SOM from terrestrial C3 and C4 plants and marine phytoplankton, supports our interpretation of the distribution of C3 and C4 land plants in the terrestrial catchment environment. [ABSTRACT FROM AUTHOR]

International Ocean Discovery Program Expedition 355 drilled Sites U1456 and U1457 in Laxmi Basin (eastern Arabian Sea) to document the impact of the South Asian monsoon on weathering and erosion of the Himalaya. We revised the chronostratigraphic framework for these sites using a combination of biostratigraphy, magnetostratigraphy and strontium isotope stratigraphy. The sedimentary section at the two sites is similar and we divided it into six units bounded by unconformities or emplaced as a mass-transport deposit (MTD). Unit 1 underlies the MTD, and is of early–middle Miocene age at Site U1456 and early Paleocene age at Site U1457. An unconformity (U1) created by emplacement of the MTD (unit 2) during the late Miocene Epoch (at c. 9.83–9.69 Ma) separates units 1 and 2 and is identified by a marked change in lithology. Unit 3 consists of hemipelagic sediment with thin interbeds of graded sandstone of late Miocene age, separated from unit 4 by a second unconformity (U2) of 0.5–0.9 Myr duration. Unit 4 consists of upper Miocene interbedded mudstone and sandstone and hemipelagic chalk deposited between c. 8 and 6 Ma. A c. 1.4–1.6 Myr hiatus (U3) encompasses the Miocene–Pliocene boundary and separates unit 4 from unit 5. Unit 5 includes upper Pliocene – lower Pleistocene siliciclastic sediment that is separated from unit 6 by a c. 0.45 Myr hiatus (U4) in the lower Pleistocene sediments. Unit 6 includes a thick package of rapidly deposited Pleistocene sand and mud overlain by predominantly hemipelagic sediment deposited since c. 1.2 Ma. [ABSTRACT FROM AUTHOR]

Abstract Surface and thermocline conditions of the Western Pacific Warm Pool (WPWP) reflect changes in regional and basin scale ocean and atmosphere circulations and in turn may affect climate globally. Previous studies suggest that a range of factors influences the WPWP on different timescales, however the precise forcings and mechanisms are unclear. Combining surface and thermocline records from sediment cores offshore Papua New Guinea we explore the influence of local and remote processes on the WPWP in response to astronomical forcing and changing glacial-interglacial boundary conditions over the past 110 kyr. We find that thermocline temperatures change with variations in Earth's obliquity with higher temperatures coinciding with high obliquity, which is attributed to variations in subduction and advection of the South Pacific Tropical Water. In contrast, rainfall variations associated with meridional migrations of the Intertropical Convergence Zone are primarily driven by changes in insolation due to precession. Records of bulk sedimentary Ti/Ca and foraminiferal Nd/Ca indicate an additional influence of obliquity, which, however, cannot unambiguously be related to changes in precipitation. Finally, our results suggest a thermocline deepening during the Last Glacial Maximum (LGM). A compilation of available proxy records illustrates a dipole-like pattern of LGM thermocline depth anomalies with a shoaling (deepening) in the northern (southern) WPWP. A comparison of the proxy compilation with an ensemble of Paleoclimate Model Intercomparison Project (PMIP) climate model simulations reveals that the spatial pattern of LGM thermocline depth anomalies is mainly attributable to a contraction of the Pacific Walker circulation on its western side. Highlights • Orbital control on precipitation over/off Papua New Guinea. • Thermocline off Papua New Guinea is influenced by obliquity-driven changes in SPTW advection. • LGM thermocline deepening associated with a contraction of the Pacific Walker cell. [ABSTRACT FROM AUTHOR]

Precipitation isotope reconstructions derived from speleothems and plant waxes are important archives for understanding hydroclimate dynamics. Their climatic significance in East Asia, however, remains controversial. Here we present terrestrial plant-wax stable hydrogen isotope ( δ D wax ) records over periods covering the last four interglacials and glacial terminations from sediment cores recovered from the northern South China Sea (SCS) as an archive of regionally-integrated precipitation isotope changes in Southeast China. Combined with previous precipitation isotope reconstructions from China, we find that the SCS δ D wax and Southwest-Central China stalagmite δ 18 O records show relatively enriched and depleted isotopic values, respectively, during interglacial peaks; but relatively similar isotopic variations during most sub-interglacials and glacial periods over the past 430 thousand years. During interglacial peaks, strong summer insolation should have intensified the convection intensity, the isotopic fractionation along moisture trajectories and the seasonality, which are all in favor of causing isotopically-depleted rainfall over the East Asian monsoon regime. These effects in combination with a relatively high proportion of Indian Ocean- versus Pacific-sourced moisture influx should have resulted in strongly depleted precipitation isotopes (stalagmite δ 18 O) over most parts of China. However, Southeast China should have been affected by a relatively low ratio of Indian Ocean- versus Pacific-sourced moisture influx, which dominated over effects yielding depleted precipitation isotopes and led to enriched precipitation isotopes ( δ D wax ). It is thus concluded that glacial boundary conditions and insolation forcing are the two most important factors for causing regional differences in precipitation isotope compositions over subtropical East Asia on orbital timescales. [ABSTRACT FROM AUTHOR]

El Niño/Southern Oscillation (ENSO) events and latitudinal shifts of the Intertropical Convergence Zone (ITCZ) cause large scale hydrologic changes in the western tropical Pacific (WTP). However, there is still a debate on the role of ENSO and ITCZ shifts on the hydroclimate in the WTP and their linkage to Northern Hemisphere climate change on glacial-interglacial timescales. For that reason, we present ice volume-corrected seawater δ 18 O (δ 18 O sw-ice , a proxy for salinity) and sea surface temperature (SST) records from IMAGES Core MD06-3047B recovered from the northern WTP to investigate the hydroclimate in the WTP during the last 700 kyr. Planktic foraminifera Globigerinoides ruber based Mg/Ca-SST and δ 18 O sw-ice records reveal distinct glacial-interglacial variations. The δ 18 O sw-ice record shows that our study site is characterized by fresher conditions and thus higher precipitation during glacials than during interglacials. Our results are in good agreement with numerical model simulations, which also suggest a glacial freshening in the northern WTP. A glacial freshening of the WTP is most likely related to a substantial weakening of the Atlantic Meridional Overturning Circulation (AMOC) and/or exposure of the Maritime Continent due to sea level changes which resulted in an enhanced Pacific Walker circulation and/or southward shift of the ITCZ. In addition, SST records from the WTP and the eastern tropical Pacific (ETP) suggest an enhanced tropical Pacific zonal SST gradient and thus La Niña-like conditions, which may have contributed to fresher conditions in the WTP during glacial periods. Besides, our rainfall record is in antiphase to the Chinese speleothem δ 18 O records, supporting the idea of an opposing trend in precipitation changes between the WTP and East Asia on orbital timescales. [ABSTRACT FROM AUTHOR]

Climate phenomena like the monsoon system, El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are interconnected via various feedback mechanisms and control the climate of the Indian Ocean and its surrounding continents on various timescales. The eastern tropical Indian Ocean is a key area for the interplay of these phenomena and for reconstructing their past changes and forcing mechanisms. Here we present records of upper ocean thermal gradient, thermocline temperatures (TT) and relative abundances of planktic foraminifera in core SO 189-39KL taken off western Sumatra (0°47.400′ S, 99°54.510′ E) for the last 8 ka that we use as proxies for changes in upper ocean structure. The records suggest a deeper thermocline between 8 ka and ca 3 ka compared to the late Holocene. We find a shoaling of the thermocline after 3 ka, most likely indicating an increased occurrence of upwelling during the late Holocene compared to the mid-Holocene which might represent changes in the IOD-like mean state of the Indian Ocean with a more negative IOD-like mean state during the mid-Holocene and a more positive IOD-like mean state during the past 3 ka. This interpretation is supported by a transient Holocene climate model simulation in which an IOD-like mode is identified that involves an insolation-forced long-term trend of increasing anomalous surface easterlies over the equatorial eastern Indian Ocean. [ABSTRACT FROM AUTHOR]

The response of the tropical climate in the Indian Ocean realm to abrupt climate change events in the North Atlantic Ocean is contentious. Repositioning of the intertropical convergence zone is thought to have been responsible for changes in tropical hydroclimate during North Atlantic cold spells, but the dearth of high-resolution records outside the monsoon realm in the Indian Ocean precludes a full understanding of this remote relationship and its underlying mechanisms. Here we show that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean. Our results are based on new, high-resolution sea surface temperature and seawater oxygen isotope records of well-dated sedimentary archives from the tropical eastern Indian Ocean for the past 45,000 years, combined with climate model simulations of Atlantic circulation slowdown under Marine Isotope Stages 2 and 3 boundary conditions. Similar conditions in the east and west of the basin rule out a zonal dipole structure as the dominant forcing of the tropical Indian Ocean hydroclimate of millennial-scale events. Results from our simulations and proxy data suggest dry conditions in the northern Indian Ocean realm and wet and warm conditions in the southern realm during North Atlantic cold spells. [ABSTRACT FROM AUTHOR]

Tests of planktic foraminifera are important tracers for reconstructing past oceanic environments. It is essential to have accurate information of the habitat depth of the planktic foraminiferal species whose isotopic and elemental signatures are being used to infer past climatic and oceanographic conditions. The planktic foraminifera species Dentoglobigerina altispira is a very common component of Miocene and Pliocene tropical to warm subtropical planktic foraminiferal assemblages but different findings exist about the habitat depth of this species from shallow to deep water. For that reason, comparative stable carbon and oxygen isotope analyses of four coexisting planktic foraminifera species from National Gas Hydrate Program Expedition Site 01 (Site NGHP-01-01A) were performed in order to reconstruct the habitat depth of D. altispira in the eastern Arabian Sea for the middle Miocene (~16–12.5 Ma). The D. altispira oxygen isotope values are on average higher than those of the shallow water reference species Trilobatus sacculifer and Globigerinoides obliquus , but still significantly lower than those for the deeper dwelling species Dentoglobigerina venezuelana. This suggests that D. altispira inhabited a deeper habitat depth than the estimated habitat depth for modern T. sacculifer in the eastern Indian Ocean (~50 m). Paired D. altispira and T. sacculifer Mg/Ca data reveal lower Mg/Ca and thus colder temperatures for D. altispira than for T. sacculifer , also suggesting that D. altispira calcified at a greater water depth than T. sacculifer. The data of this study suggest that D. altispira inhabited the lower mixed layer and/or upper thermocline in the eastern Arabian Sea during the middle Miocene. • Habitat depth of the planktic foraminifera Dentoglobigerina altispira in the eastern Arabian Sea during the middle Miocene. • Dentoglobigerina altispira inhabited the lower mixed layer and/or upper thermocline. • Dentoglobigerina altispira may be used in combination with shallow dwellers to reconstruct upper water column stratification. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the Strontium/Calcium (Sr/Ca) ratio, and the carbon and oxygen isotopic compositions of coccoliths are investigated in three different grain-size fractions (<20 μm, 15–5 μm, <5 μm) of 17 surface sediment samples from the Equatorial and South Atlantic. The results are compared to environmental parameters in order to assess the factors controlling the observed coccolith geochemical patterns. Isotopic and geochemical composition of coccolith species in surface sediment samples from the South Atlantic greatly varies according to the different grain-size fractions. However, even if the absolute values show a great offset, the general trends are comparable. The δ18O values show a decreasing trend with increasing temperature. The δ13C and Sr/Ca ratio are mainly influenced by productivity of coccolithophores, which is in turn controlled by different factors, such as temperature, nutrient supply and productivity of other phytoplankton groups. Dilution and dissolution are negligible factors in these open marine samples. Therefore, coccolith abundance in bulk sediment is the best approximation for productivity of coccolithophores. The various coccolith species fractionate Sr differently, as is best shown by the 5–15 μm fraction where three species (Calcidiscus leptoporus, Helicosphaera carteri and Coccolithus pelagicus) predominantly occur. [Copyright &y& Elsevier]

Abstract: We present a new high precision analytical method for the determination of Mg/Ca and Sr/Ca ratios in carbonates using an inductively coupled plasma quadrupole mass spectrometer (ICP-QMS) with a 650-W cold plasma technique and a desolvation introduction system. Signal intensities are detected in pulse-counting mode and Mg/Ca and Sr/Ca ratios are calculated directly from intensity ratios of 24Mg/43Ca and 86Sr/43Ca using external matrix-matched standards for every 4–5 samples to correct for instrumental mass discrimination and low-frequency ratio drift. Significant matrix effect of Ca content on Mg/Ca determination (−0.018 Mg/Ca (mmol/mol)/[Ca] (ppm)), can be overcome by diluting [Ca] to 6–8 ppm in the sample solution or using an empirical correction. The Sr/Ca ratio affects the Mg/Ca determination, with a factor of −0.32% Mg/Ca per mmol/mol. This is mainly caused by the influence of doubly charged 86Sr, which biases the intensity measurement of the 43Ca+ ion beam. This effect results in a trivial offset of less than 0.1% on Mg/Ca measurements for Quaternary foraminiferal and coral samples. The internal precision of our method ranges from 0.1 to 0.2%. Replicate measurements made on standards and samples show long-term external uncertainties (2σ) of Mg/Ca=0.84% and Sr/Ca=0.49%. The minimum sample size requirement is only 3.5 μg of carbonate. The application of this newly developed technique on the planktonic foraminifera Globigerinoides ruber from a core recovered in the southern South China Sea yields a glacial–interglacial difference in sea surface temperature (SST) of 3 °C. Three-year coral Sr/Ca data suggest that the seasonal SST ranged from 22.6–23.8 °C in winter to 26.9–27.9 °C in summer in Nanwan, south Taiwan, during 2000–2002. The coral-Sr/Ca inferred SSTs in 2002 match well with instrumental records, which demonstrates the validity of this ICP-QMS method. [Copyright &y& Elsevier]

Variations in thermoclinal conditions play an important role in the evolution of the Western Pacific Warm Pool (WPWP) and in connecting the tropical and extratropical regions of the Pacific Ocean. However, secular thermoclinal changes in the northwestern part of the WPWP and their forcing mechanisms are not yet well understood, particularly on orbital timescales. In this study, we report thermoclinal variation at Site MD06-3047 B in the western Philippine Sea over the last 700 kyr. Our data show that variations in thermocline temperature and salinity in the study area were correlated with changes in Earth's obliquity, with warmer and saltier (colder and fresher) thermocline waters corresponding to high (low) Earth-axial obliquity. At high obliquity, increases in thermocline temperature and salinity may have been linked to advection of warm North Pacific tropical water. In the study area, a lower (higher) vertical temperature gradient in the upper water column suggests a deeper (shallower) thermocline during glacials (interglacials). The main factor leading to thermoclinal deepening during glacials was strengthening of the East Asian winter monsoon (EAWM), and more La Niña-like conditions may have contributed to concurrent subsurface warming and thus thermoclinal deepening. In-phase thermoclinal deepening in the northern and peri-equatorial southern WPWP during glacial stages may have been triggered by changes in glacial boundary conditions, such as increased ice sheet thickness, through intensification of the EAWM and strengthening of the tropical Trade Winds. • Analysis of thermocline dynamics in northwestern tropical Pacific since 700 ka. • Minimal glacial-interglacial changes in thermocline temperature and salinity. • Obliquity-paced thermocline changes linked to NPTW influences. • Glacial thermocline deepening linked to EAWM and stronger Walker Circulation. • Thermocline deepening across WPWP due to intensified Northern Hemisphere glaciation. [ABSTRACT FROM AUTHOR]

To identify environmental causes for past changes in vegetation in subtropical East Asia, we present carbon isotope compositions of plant-wax n -alkanes and provide estimates of the C 4 -plant contribution across the past four glacial terminations and interglacials, based on cores recovered from the northern South China Sea. Our results show a comparable C 4 -plant contribution between the Last Glacial Maximum (LGM) and the Holocene. An increase of the C 4 -plant contribution by 15–20% is found for Terminations IV, II and I relative to subsequent interglacial peaks, coeval with an expansion of Cyperaceae and Poaceae. In contrast, Termination V reveals a lower C 4 -plant contribution than Marine Isotope Stage (MIS) 11c. The data exhibit a long-term trend, with a stepwise increase of the C 4 -plant contribution across interglacials MIS 11c, 9e, 7e and 1. We suggest that no substantial changes in humidity levels over glacial-interglacial cycles occurred facilitating a similar C 3 /C 4 -plant ratio for the LGM and the Holocene. Instead, deglacial sea-level rises caused an extensive development of floodplains and wetlands on the exposed continental shelf, providing habitats for the spread of C 4 sedges and grasses. The progressive subsidence of Chinese coastal areas and the broadening of the continental shelf over the late Quaternary explains the nearly absence of C 4 plant occurrence during Termination V and a gradual increase of the C 4 -plant contribution across interglacial peaks. Taken together, changes in coastal environments should be considered when interpreting marine-based vegetation reconstructions from subtropical Asia. • High-resolution plant-wax δ13C records for past four interglacials and glacial terminations. • C 4 -plant expansions on the exposed continent shelf occurred over glacial terminations. • Changes in coastal environments rather than climate cause alterations of vegetation composition. • Progressive broadening of the continental shelfs explains long-term vegetation changes. [ABSTRACT FROM AUTHOR]