Zhonghui Liu - Academia.edu (original) (raw)

Papers by Zhonghui Liu

Neuroreport, Jan 2, 2016

Activin A, a member of the transforming growth factor β superfamily, plays an important role in t... more Activin A, a member of the transforming growth factor β superfamily, plays an important role in the central nervous system as a neurotrophic and neuroprotective factor. The hypothalamic paraventricular nucleus (PVN) in the central nervous system is characterized as an important integrative site to regulate arterial pressure (AP). However, whether activin A in the PVN is involved in the regulation of AP is not well characterized. This study aimed to determine the effect of activin A on AP in the PVN in rats. The results showed that activin βA, activin type IIA and IIB receptors (ActRIIA and ActRIIB), and Smad2 and Smad3 mRNA expressions were detectable in the PVN of WKY rats by reverse-transcription PCR, and the expression of ActRIIA protein in the PVN was further confirmed by immunohistochemical staining. A microinjection of angiotensin II (AngII) (0.1 nmol/100 nl) or activin A (2 ng/100 nl) into the PVN increased AP significantly in WKY rats (P<0.05). Moreover, activin A (5 ng/m...

Geochimica Et Cosmochimica Acta, 2008

The alkenone unsaturation index U K 0 37 has been applied to reconstruct past temperature changes... more The alkenone unsaturation index U K 0 37 has been applied to reconstruct past temperature changes in both marine and lacustrine systems. However, few studies have addressed whether the relative abundance of the C 37:4 alkenone to the total C 37 production (%C 37:4 ) can reflect surface salinity changes in lacustrine systems. Here we present long-chain C 37 alkenone distribution patterns in surface sediments from Lake Qinghai, China. Surface sediments were sampled over a large range of surface salinity changes (1.7-25 g/l) within Lake Qinghai and its surrounding lakes, while temperature differences at these sampling locations should be relatively small. We have found that %C 37:4 varies from 15% to 49% as surface salinity decreases. We tentatively describe this %C 37:4 -salinity link with a general linear regression: %C 37:4 = 53.4 (±7.8) À 1.73 (±0.45) · S (n = 28, r 2 = 0.62), although step-wise %C 37:4 changes in response to salinity variation may exist. U K 0 37 values vary between 0.10 and 0.16 at these sites and the inferred range of lake water temperature changes is $2-3°C, suggesting that U K 0 37 largely reflects temperature signal across a large salinity range, consistent with previous findings that U K 0 37 can indicate temperature changes over a large diversity of environmental settings. We have also found that U K 0 37 values are correlated with salinity changes (r 2 = 0.4), and thus cannot exclude potential temperature effect on %C 37:4 and salinity effect on U K 0 37 in this study. However, even extreme estimates of temperature differences within the lake are still unable to explain the observed %C 37:4 changes. We therefore suggest that %C 37:4 could be used to infer past lake salinity changes at a regional scale.

Geochimica Et Cosmochimica Acta Supplement, Jul 1, 2008

In general, long-and short-term global temperature changes are commonly ascribed to parallel chan... more In general, long-and short-term global temperature changes are commonly ascribed to parallel changes in pCO2. Support for this CO2-climate relationship can be found in the decline in alkenone-based pCO2 estimates from the mid-Eocene to the Miocene, which generally ...

International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience, 2015

Journal of Asian Earth Sciences, 2015

Central China has experienced stronger summer monsoon during warm periods such as Marine Isotope ... more Central China has experienced stronger summer monsoon during warm periods such as Marine Isotope Stages (MIS) 1 and 3, and weaker summer monsoon during cool periods such as MIS 2. The evolution history of Dajiuhu subalpine peatland in central China can help investigate how the expansion and shrinkage of peatland were associated with monsoonal strength over the last glacial-interglacial cycle. Here we apply bulk organic carbon and molecular biomarkers (hopane and n-alkane) to reconstruct the evolution history for the Dajiuhu peatland over the past 40,000 yr. The results indicate fluctuations between lacustrine and peat-like deposition during MIS 3, steady lacustrine deposition during MIS 2, and peatland initiation and expansion during MIS 1 in the Dajiuhu peatland. Therefore, at the glacial-interglacial scale, warmer summer and cooler winter conditions in interglacial periods are crucial to trigger peat deposition, whereas reduced evaporation in glacial period instead of decreased monsoonal-driven precipitation would have played a predominant role in the regional effective moisture balance. However, within the Holocene (MIS 1), monsoonal precipitation changes appear to be the main controller on millennial-scale variations of water-table level of the Dajiuhu peatland.

The last major climatic transition in Earth's history occurred between the Pliocene and Plei... more The last major climatic transition in Earth's history occurred between the Pliocene and Pleistocene epochs. This transition witnessed a substantial increase in the variance of Earth's climate in response to changes in orbital obliquity at ˜3 Ma, approximately coincident with the onset of Northern Hemisphere glaciation. A recent theory suggests that the start of this transition also marks a fundamental shift in the ocean's heat budget from a state of local equilibrium prior to ˜3 Ma, to a state in which heat absorbed in low latitude upwelling zones is balanced by heat removed at high latitudes after ˜3 Ma. In this remotely balanced state, changes in the distribution of high latitude insolation due to changes in orbital obliquity can be communicated from the high to low latitudes via the thermocline. To evaluate this theory, we use the alkenone organic proxy on sediments from Ocean Drilling Program (ODP) Site 846 (3° S, 91° ºW) in the Eastern Equatorial Pacific (EEP), documenting orbital scale variations in sea surface temperature (SST) and productivity in the largest upwelling zone on Earth over the past 5 Myrs. Our Uk'37 temperature record shows that SST decreased by ˜1° C/Myrs from a high of 28° C in the early Pliocene to a low of 20° C in the late Pleistocene. A dramatic increase in paleoproductivity occurred ˜3 Ma followed by a sharp decline ˜1.5 Ma. Evolutive spectral analysis of sea surface indices and benthic oxygen isotope data from ODP Site 846 show that before 1 Ma all three proxies were dominated by obliquity variations and that these variations were modulated by the 1.2 Myr obliquity envelope. Evolutionary cross-spectra further indicate that in the obliquity band, the phase relationships between these three climatic indices remain essential constant throughout the entire 5 Myr interval, with EEP SST and paleoproductivity essentially in phase and both of these proxies leading benthic delta 18O by ˜4 kyrs. The constancy of phase between SST, paleoproductivity, and ice volume implies that the physical mechanisms governing the climate of the EEP have persisted for at least the past 5 Myrs and that the high latitudes and the tropics were linked at least 2 Myrs before the onset of Northern Hemisphere glaciation. These results do not rule out a major reorganization of the sources and sinks of the Earth's heat budget, but suggest that if it occurred, it took place prior to 5 Ma. However, the EEP was not entirely unaffected by the onset of Northern Hemisphere glaciation. The major increase in productivity and cooling of SST at ˜3 Ma suggest a dramatic strengthening of the EEP upwelling system at this time.

Quaternary Research, 2015

We investigate the distribution of archaeal lipids in a 5.8-m-long sedimentary core recovered fro... more We investigate the distribution of archaeal lipids in a 5.8-m-long sedimentary core recovered from Lake Qinghai to extract regional hydroclimate and temperature signals since the last deglaciation for this important region. The paleohydrology was reconstructed from the relative abundance of thaumarchaeol (%thaum) and the archaeol and caldarchaeol ecometric (ACE) index. The %thaum-inferred lake-level record was extended to deglaciation, showing three periods (11.9-13.0, 14.1-14.7 and 15.1-17.2 cal ka BP) with relatively higher lake levels than those during the early Holocene. The ACE record demonstrates three periods (10.6-11.2, 13.2-13.4 and 17.4-17.6 cal ka BP) of elevated salinity when the lake was shallow. Filtered TEX 86 record based on archaeal lipid distributions corresponded to relatively higher lake levels, implying that a certain lake size is required for using the TEX 86 paleothermometer. At 1-4 cal ka BP, the reconstructed temperature fluctuated significantly and correlated negatively with inferred lake level, indicating that lake temperature and hydrological change might be coupled during this period. We attribute this co-variance to the importance of summer temperature in controlling evaporation for this arid/semi-arid region. Moreover, our results indicate that archaeal lipids have potential in reconstructing paleoclimate patterns from lacustrine sedimentary cores, but the data should be interpreted with care.

IET Signal Processing, 2014

ABSTRACT Chaotic compressive sensing is a nonlinear framework for compressive sensing. Along the ... more ABSTRACT Chaotic compressive sensing is a nonlinear framework for compressive sensing. Along the framework, this paper proposes a chaotic analog-to-information converter, chaotic modulation, to acquire and reconstruct band-limited sparse analog signals at sub-Nyquist rate. In the chaotic modulation, the sparse signal is randomized through state modulation of continuous-time chaotic system and one state output is sampled as compressive measurements. The reconstruction is achieved through the estimation of the sparse coefficients with principle of chaotic impulsive synchronization and Lp-norm regularized nonlinear least squares. The concept of supreme local Lyapunov exponents (SLLE) is introduced to study the reconstructablity. It is found that the sparse signals are reconstructable, if the largest SLLE of the error dynamical system is negative. As examples, the Lorenz system and Liu system excited by the sparse multi-tone signals are taken to illustrate the principle and the performance.

Cellular & molecular immunology, 2009

Macrophages play critical roles in innate immune and acquired immune via secreting pro-inflammato... more Macrophages play critical roles in innate immune and acquired immune via secreting pro-inflammatory mediators, phagocytosing microorganisms and presenting antigens. Activin A, a member of transforming growth factor beta (TGF-beta) superfamily, is produced by macrophages and microglia cells. In this study, we reported a direct effect of activin A as a pro-inflammatory factor on mouse macrophage cell line RAW264.7 cells. Our data revealed that activin A could not only increase IL-1 beta and IL-6 production from RAW264.7 cells, but also promote pinocytic and phagocytic activities of RAW264.7 cells. In addition, activin A obviously up-regulated MHC II expression on the surface of RAW264.7 cells, whereas did not influence MHC I expression. Activin A also enhanced CD80 expression, which is a marker of activated macrophages, but did not influence RAW264.7 cell proliferation. These data suggest that activin A may regulate primary macrophage-mediated innate and acquired immune response via p...

Nature Geoscience, 2015

Precipitation in low latitudes is primarily controlled by the position of the intertropical conve... more Precipitation in low latitudes is primarily controlled by the position of the intertropical convergence zone, which migrates from south to north seasonally. The Little Ice Age (defined as AD 1400-1850) was associated with low solar irradiance and high atmospheric aerosol concentrations as a result of several large volcanic eruptions. The mean position of the intertropical convergence zone over the western Pacific has been proposed to have shifted southwards during this interval, which would lead to relatively dry Little Ice Age conditions in the northern extent of the intertropical convergence zone and wet conditions around its southern limit. However, here we present a synthesis of palaeo-hydrology records from the Asian-Australian monsoon area that documents a rainfall distribution that distinctly violates the expected pattern. Our synthesis instead documents a synchronous retreat of the East Asian Summer Monsoon and the Australian Summer Monsoon into the tropics during the Little Ice Age, a pattern supported by the results of our climate model simulation of tropical precipitation over the past millennium. We suggest that this pattern over the western Pacific is best explained by a contraction in the latitudinal range over which the intertropical convergence zone seasonally migrates during the Little Ice Age. We therefore propose that rather than a strict north-south migration, the intertropical convergence zone in this region may instead expand and contract over decadal to centennial timescales in response to external forcing.

PLOS ONE, 2015

Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role ... more Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14 C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment.