Coherence between solar activity and the East Asian winter monsoon variability in the past 8000 years from Yangtze River-derived mud in the East China Sea

AMS(14)C dating and grain-size analysis for Core PC-6, located in the middle of a mud area on the inner shelf of the East China Sea (ECS), were used to rebuild the Holocene history of the East Asian winter monsoon (EAWM). The 7.5-m core recorded the history of environmental changes during the postglacial transgression. The core's mud section (the upper 450 cm) has been formed mainly by suspended sediment delivered from the Yangtze River mouth by the ECS Winter Coastal Current (ECSWCC) since 7.6 kyr BP. Using a mathematical method called "grain size vs. standard deviatioW', we can divide the Core PC-6's grain-size distribution into two populations at about 28 mu m. The fine population (< 28 mu m) is considered to be transported by the ECSWCC as suspended loads. Content of the fine population changes little and represents a stable sedimentary environment in accord with the present situation. Thus, variation of mean grain-size from the fine population would reflect the strength of ECSWCC, which is mainly controlled by the East Asian winter monsoon. Abrupt increasing mean grain size in the mud section is inferred to be transported by sudden strengthened ECSWCC, which was caused by the strengthened EAWM. Thus, the high resolution mean grain-size variation might serve as a proxy for reconstruction of the EAWM. A good correlation between sunspot change and the mean grain-size of suspended fine population suggests that one of the primary controls on centennial- to decadal-scale changes of the EAWM in the past 8 ka is the variations of sun irradiance, i.e., the EAWM will increase in intensity when the number of sunspots decreases. Spectral analyses of the mean grain-size time series of Core PC-6 show statistically significant periodicities centering on 2463, 1368, 128, 106, 100, 88-91, 7678, and 70-72 years. The EAWM and the East Asian summer monsoon (EASM) agree with each other well on these cycles, and the East Asian Monsoon (EAM) and the Indian Monsoon also share in concurrent cycles in Holocene, which are in accord with the changes of the sun irradiance. (c) 2005 Elsevier B.V. All rights reserved.

Preparation, structural characterization and in vitro antitumor activity of kappa-carrageenan oligosaccharide fraction from Kappaphycus striatum

Oligosaccharides were prepared through mild hydrochloric acid hydrolysis of kappa-carrageenan from Kappaphycus striatum to compare the antitumor activity with carrageenan polysaccharides. Oligosaccharide fractions were isolated by gel permeation chromatography and the structure of fraction 1 (F1) was studied by using negative- ion electrospray ionization-mass spectrometry (ESI-MS), and H-1 and C-13-NMR spectrometry. The in vitro antitumor effects in three human neoplastic cell lines (KB, BGC, and Hela) of polysaccharides and F1 were investigated. The bioassay results showed that F1 exhibited relatively higher antitumor activity against the three cancer cells than polysaccharides.

Morphology and Molecular Phylogeny of Trimyema koreanum n. sp., a Ciliate from the Hypersaline Water of a Solar Saltern

A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293 parts per thousand) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 x 13 mu m in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.).

In vivo antioxidant activity of polysaccharide fraction from Porphyra haitanesis (Rhodephyta) in aging mice

Sulfated polysaccharide fraction F2 from Porphyra haitanesis (Rhodephyta) showed inhibitory effect on the in vitro lipid peroxidation. In the present study, the age-related changes in the antioxidant enzyme activity, lipid peroxidation, and total antioxidant capacity (TAOC) in different organs in mice were investigated and the in vivo antioxidant effect of F2 in aging mice was checked. Increased endogenous lipid peroxidation and decreased TAOC were observed in aging mice. Intraperitoneal administration of F2 significantly decreased the lipid peroxidation in a dose-dependent manner. F2 treatment increased TAOC and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in all the organs tested in aging mice. It is concluded that the sulfated polysaccharide fraction F2 can be used in compensating the decline in TAOC and the activities of antioxidant enzymes and thereby reduces the risks of lipid peroxidation. (C) 2003 Elsevier Science Ltd. All rights reserved.

岱海岩芯沉积的粒度组成与湖区全新世降水变化历史

Sediment cores DH99a and DH99b recovered in the central part of Daihai Lake in north-central China were analysed at 2- to 4-crn intervals for grain-size distribution. Grain-size distributions of the lake sediments are inferred to be a proxy for past changes in East Asian monsoon precipitation, such that greater silt-size percentage and higher median grain size reflect increased monsoonal precipitation rates. The grain-size record of Daihai Lake sediments spanning the last ca 11,000 yr indicates that the monsoonal precipitation in the lake region can be divided into three stages: the Early, Middle and Late Holocene. During the Early Holocene before ca 7900 cal yr BP, the median grain size (Md) and the silt-fraction content were relatively low and constant, suggesting relatively low precipitation over the lake region. The Middle Holocene between ca 7900 and 3100 cal yr BP was marked by intensified and highly variable monsoonal precipitation, as indicated by high and variable Md values and silt contents of the lake sediments. During this period, average precipitation rate gradually increased from ca 7900 to 6900 cal yr BP, displayed intense oscillations between ca 6900 and 4400 cal yr BP, and exhibited a decreasing trend while fluctuating from ca 4400 to 3100 cal yr BP Although generally high during the Middle Holocene, both the Md and the silt content assumed distinctly low values at the short intervals of ca 6500-6400, 6000-5900, 5700-5600, 4400-4200 cal yr BP, implying that monsoonal precipitation might have been significantly reduced during these intervals. During the Late Holocene since ca 3100 cal yr BP, grain-size values suggest that precipitation decreased. However, during the Late Holocene, relatively higher Md values and silt contents occurring between ca 1700 to 1000 cal yr BP may denote an intensification of hydrological cycles in the lake area. Changes in the East Asian monsoonal precipitation were not only directly linked with the changing seasonality of solar insolation resulting from progressive changes in the Earth's orbital parameters, but also may have been closely related to variations in the temperature and size of the Western Pacific Warm Pool, in the intensity of the El Nino-Southern Oscillation, and in the path and strength of the North Equatorial Current in the western Pacific.