Estimating Areal Production of Intertidal Microphytobenthos based on Spatio-Temporal Community Dynamics and Laboratory Measurements

Guo Ying Du,정익교 한국해양과학기술원 2009 Ocean science journal Vol.44 No.4

In situ Microphytobenthic community dynamics were combined with laboratory measurement of predominant species by fluorescence methods to estimate the areal primary production. Field investigation of community dynamics of microphytobenthos (MPB) was conducted from August 2006 to August 2007 in intertidal flats of the Nakdong River estuary, Korea. MPB Biomass varied between 0.47 and 16.58 μg cm−3 in the surface 1 cm sediment, with two dominant diatom species, Amphora coffeaeformis and Navicula sp., occupying average 77.2 ± 14.9% of total number of MPB cells. The biomass was higher in the slightly muddy sand sites than that in the sand site, and showed different pattern of seasonal variation. The profile of vertical distribution of biomass was an exponential decrease trend with depth in sediments. The biomass proportions in the uppermost 3 mm were 57.6% and 37.8% with and without the presence of biofilm, respectively. The two dominant species were cultured in laboratory, and their photosynthetic parameters, rETRmax (relative maximum electron transport rate), α (light utilization coefficient) and Ek (light saturation parameter) were derived from rETR (relative ETR)-irradiance curves by Imaging- PAM (pulse amplitude modulated) fluorometry. The rETR-irradiance curves showed no significant difference of photosynthetic activities between the two species. The areal potential production ranged from 0.74 to 2.22 g C m−2 d−1. In situ Microphytobenthic community dynamics were combined with laboratory measurement of predominant species by fluorescence methods to estimate the areal primary production. Field investigation of community dynamics of microphytobenthos (MPB) was conducted from August 2006 to August 2007 in intertidal flats of the Nakdong River estuary, Korea. MPB Biomass varied between 0.47 and 16.58 μg cm−3 in the surface 1 cm sediment, with two dominant diatom species, Amphora coffeaeformis and Navicula sp., occupying average 77.2 ± 14.9% of total number of MPB cells. The biomass was higher in the slightly muddy sand sites than that in the sand site, and showed different pattern of seasonal variation. The profile of vertical distribution of biomass was an exponential decrease trend with depth in sediments. The biomass proportions in the uppermost 3 mm were 57.6% and 37.8% with and without the presence of biofilm, respectively. The two dominant species were cultured in laboratory, and their photosynthetic parameters, rETRmax (relative maximum electron transport rate), α (light utilization coefficient) and Ek (light saturation parameter) were derived from rETR (relative ETR)-irradiance curves by Imaging- PAM (pulse amplitude modulated) fluorometry. The rETR-irradiance curves showed no significant difference of photosynthetic activities between the two species. The areal potential production ranged from 0.74 to 2.22 g C m−2 d−1.

Temporal variation in the vertical distribution of microphytobenthos in intertidal flats of the Nakdong River estuary, Korea

Du, Guo Ying,Son, Moonho,An, Soonmo,Chung, Ik Kyo Elsevier 2010 Estuarine, coastal and shelf science Vol.86 No.1

<P><B>Abstract</B></P><P>The vertical distribution of microphytobenthos (MPB) was investigated in intertidal flats of the Nakdong River estuary over different temporal periods. The MPB biomass were measured as chlorophyll <I>a</I> concentration in the sediment, and monitored at two different depth scales. From August 2006 to August 2007, monthly sampling was carried out at four sites to a depth of 10cm. The vertical distribution exhibited an exponential decline with depth and the slope was closely related to sediment composition and MPB biomass in the surface sediment. The two slightly muddy sand (5–25% mud, <63μm) sites presented similar trends of seasonal variation to a sediment depth of 10cm, and no statistical difference was observed in their initial values and the slope of the exponential curves applied to each data set. The site with higher mud content also had higher surface biomass, and the fitted exponential curve had a larger slope than sites with more sand content. The seasonal variations of phaeo-pigments compared to chlorophyll <I>a</I> revealed higher grazing stress on the MPB in summer at the three slightly muddy sand sites, and low grazing stress all year around at the sand (<5% mud) site. In January, April and October 2007, and January 2008, diurnal sampling was conducted at hourly intervals at one slightly muddy sand site. The investigation in January 2007 which was conducted at 1cm intervals to a depth of 10cm sediment showed the migration mainly existed in the upper 1cm. The other diurnal sampling was undertaken to a 1cm depth at 0.5mm intervals. An evident migratory rhythm was present, with migration up to the surface during daytime emersion and down into deeper sediment during night and high tide submersion. Migrating cells could reach sediments as deep as 6 or even 10mm. When the visible thick biofilms formed, the migratory rhythm changed by keeping higher biomass at the surface even at night and during high tide submersion. Generally, the MPB surface biomass was an important factor in structuring the MPB vertical distribution. The vertical distribution to depths of 10cm was closely related to the sediment composition over the long term, while the MPB migration influenced the vertical distribution over the short term in the top 1cm of the sediment.</P>

Effect of light and sediment grain size on the vertical migration of benthic diatoms

Du, Guo Ying,Oak, Jung-Hyun,Li, Hongbo,Chung, Ik-Kyo The Korean Society of Phycology 2010 ALGAE Vol.25 No.3

Using chlorophyll fluorescence, the vertical migration of benthic diatoms responding to light intensity and affected by sediment grain size was studied. Minimal fluorescence ($F_o$) of surface sediment was measured by imaging pulse amplitude modulated (Imaging-PAM) fluorometer, and used to monitor diatom biomass variation in surface sediments. The test diatoms, Amphora coffeaeformis (C. Agardh) K$\ddot{u}$tzing and Cylindrotheca closterium (Ehrenberg) Reimann & Lewin, migrated to the sediment surface under irradiance from 50 to 500 ${\mu}mol$ photons $m^{-2}s^{-1}$. However, the diatoms exhibited no evident increase of surface biomass under dark conditions, and even showed slightly decrease of surface biomass under irradiances over 1,000 ${\mu}mol$ photons $m^{-2}s^{-1}$. The light intensity inducing the maximum surface migration of A. coffeaeformis was 100 ${\mu}mol$ photons $m^{-2}s^{-1}$, while the light intensity producing the same effect for C. closterium was 250 ${\mu}mol$ photons $m^{-2}s^{-1}$. C. closterium showed higher motility than A. coffeaeformis. Faster diatom surfacing was observed in larger grain size sediments (125-335 ${\mu}m$) than smaller ones (63-125 ${\mu}m$). This study confirmed the significant influence of light as a main triggering factor behind migration, indicated the distinct effect of different sediment grain size, and highlighted the species-specific migratory ability.

Effect of light and sediment grain size on the vertical migration of benthic diatoms

Guo Ying Du,옥정현,Hongbo Li,정익교 한국조류학회I 2010 ALGAE Vol.25 No.3

Using chlorophyll fluorescence, the vertical migration of benthic diatoms responding to light intensity and affected by sediment grain size was studied. Minimal fluorescence (Fo) of surface sediment was measured by imaging pulse amplitude modulated (Imaging-PAM) fluorometer, and used to monitor diatom biomass variation in surface sediments. The test diatoms, Amphora coffeaeformis (C. Agardh) Kützing and Cylindrotheca closterium (Ehrenberg) Reimann & Lewin,migrated to the sediment surface under irradiance from 50 to 500 μmol photons m-2 s-1. However, the diatoms exhibited no evident increase of surface biomass under dark conditions, and even showed slightly decrease of surface biomass under irradiances over 1,000 μmol photons m-2 s-1. The light intensity inducing the maximum surface migration of A. coffeaeformis was 100 μmol photons m-2 s-1, while the light intensity producing the same effect for C. closterium was 250μmol photons m-2 s-1. C. closterium showed higher motility than A. coffeaeformis. Faster diatom surfacing was observed in larger grain size sediments (125-335 μm) than smaller ones (63-125 μm). This study confirmed the significant influence of light as a main triggering factor behind migration, indicated the distinct effect of different sediment grain size,and highlighted the species-specific migratory ability.

Migratory Responses of Benthic Diatoms to Light and Temperature Monitored by Chlorophyll Fluorescence

Guo Ying Du,Wen Tao Li,Hongbo Li,정익교 한국식물학회 2012 Journal of Plant Biology Vol.55 No.2

As an important adaptation for survival in the sediments of intertidal flats, benthic diatoms move up and down in response to a wide range of environmental stimuli. We investigated the vertical migration of two diatoms—Cylindrotheca closterium (Agradh) Kützing (B-25) and Nitzschia sp. (B-3)—under different combinations of light intensity and temperature conditions. An imaging pulse amplitude modulated (PAM) fluorometer was used to measure the minimum fluorescence (F0) in order to monitor variations in diatom biomass in surface sediments. Rapid light curves (RLCs) were applied to assess their photosynthetic activities. Both species had increased motility under higher temperatures, with the longer valved C. closterium being twice as fast as the shorter valved Nitzschia sp. The former was also influenced by exposure to light intensities of 100 or 250 μmol m−2 s−1, whereas the latter was not. Consequently, no light/temperature interaction effect was associated with the vertical migration of Nitzschia sp., perhaps because of its lower photosynthetic capacity and smaller cell size. Therefore, we conclude that motile benthic diatoms exhibit species-specific responses to light and temperature due to differences in their photosynthetic capability and morphological characteristics.

Study on crystallization kinetics and curing mechanism of the multiple heavy metals in slag glass-ceramics

Yongsheng Du,Ying Wei,Zhicheng Zheng,Yuhang Guo,Hongxia Zhang,Leibo Deng,Hua Chen,Ming Zhao 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.2

In this paper, manganese-containing blast furnace slag (MBFS) was used as the main raw material and Cr2O3 was used asthe nucleating agent to prepare MBFS glass-ceramic by melting method. The influence of multiple heavy metal ions on thecrystallization characteristics, physical and chemical properties of glass-ceramic was studied by adding CuO and ZnO, and theexistence of multiple heavy metal ions in glass-ceramic and its curing effect were determined. The results showed that Cr wasthe key element for crystallization of glass-ceramic, which can enable volume crystallization to occur. The glass-ceramics withdiopside as the main crystalline phase had excellent comprehensive physical and chemical properties. The results of TCLPheavy metal leaching experiments also confirmed that spinel crystal wrapped by diopside and glass phase can produce anexcellent solidification effect on multiple heavy metals.

Constituents from Zhuyeqing Liquor with hepatoprotective effect on alcohol-induced HepaG 2 toxicity

Hong-Ying Gao,Guo-Yu Li,Hang-Yu Wang,Jian Huang,Xiao-Wei Du,Ying Han,Li-Fei Wang,Jin-Hui Wang 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.5

An unprecedented new skeleton compound (1R,10R, 11S)-10,11-dimethyl-4-formyl-2,9-dioxa-bicyclo [5.4.0]undeca-4,6-dien-3-one (1), monoterpenoids and monoterpeneglycoside picrocrocinic ester (2), epijasminoside B (3) and 60 -O-(3-methoxyl-4-hydroxyl-coumaroyl)-epijasminoside B (4),along with 26 known compounds, were obtained fromZhuyeqing Liquor. These compounds were identified mainlyby analyzing their NMR, HR-ESI–MS and CD data. The isolatedcompounds were screened against alcohol induced HepaG2 toxicity for hepatoprotective assay. Compounds 10, 19,21 and 26 displayed the highest potency against alcoholinduced HepaG 2 toxicity with the cell viability ratio 41.21,56.91, 67.69 and 70.32 % respectively.

Study on the structure of reduced graphene oxide prepared by different reduction methods

Xiang Xu,Zhu Ying,Gao Changqin,Du Han,Guo Chunwen 한국탄소학회 2022 Carbon Letters Vol.32 No.2

The reduced graphene oxide (rGO) has attracted more and more attention in recent years. How to choose a suitable reduction method to prepare rGO is a critical problem in the preparation of graphene composites. In this work, the differences of rGO reduced by thermal, microwave, Ultraviolet (UV) and reducing agent were studied. The reduction degree and functional groups of rGO were compared by SEM, XPS, Raman, FTIR and TGA. Thermal can remove most of the oxygen-containing groups of graphene oxide (GO) and the thermal reduction is the most effective reduction method. UV light can directly act on the unstable oxygen-containing groups, and its reduction efficiency is second only to thermal reduction. The efficiency of chemical reduction is not as good as that of UV reduction, because the reducing agent only act on the surface of GO. Microwave reduction is a mild thermal reduction with the lowest efficiency, but the residual oxygen-containing groups increase the hydrophilicity of rGO. To sum up, this work studies that rGO prepared by different reduction methods has different characteristics, which provides a reference for selecting appropriate reduction methods to prepare graphene composites with better properties.

In Vitro and In Vivo Immunomodulatory Activity of Okra (Abelmoschus esculentus L.) Polysaccharides

Huricha Chen,Hanwei Jiao,Ying Cheng,Kailian Xu,Xiaoxiao Jia,Qiaoyun Shi,Shiyu Guo,Manchuriga Wang,Li Du,Fengyang Wang 한국식품영양과학회 2016 Journal of medicinal food Vol.19 No.3

Crude okra (Abelmoschus esculentus L.) polysaccharide (RPS) was obtained by water extraction and alcohol precipitation. Three purified fractions of RPS, designated RPS-1, RPS-2, and RPS-3, were fractioned by diethylaminoethyl (DEAE)-cellulose chromatography. Their molecular weights, monosaccharide compositions, infrared (Fourier transform infrared [FT-IR]) spectra, and nuclear magnetic resonance (NMR) spectra were analyzed. Their immunomodulatory activity was evaluated with an in vitro cell model (RAW264.7 cells). In vivo immunomodulatory activity of RPS-2 was evaluated in normal and cyclophosphamide-induced immunosuppressed mice. The results showed that the molecular weights of RPS-1, RPS-2, and RPS-3 were 600, 990, and 1300 kDa, respectively. RPS-1 and RPS-2 were mainly composed of galactose, rhamnose, galacturonic acid, and glucuronic acid, while RPS-3 was mainly composed of galactose, rhamnose, galacturonic acid, glucuronic acid, and glucose. FT-IR and NMR spectrum data indicated a rhamnogalacturonan I characteristic of polysaccharide. Both RPS and its purified fractions RPS-1, RPS-2, and RPS-3 significantly increased RAW264.7 cell proliferation, nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression, and tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-10 secretion (P < .05). The purified fraction RPS-2 also increased the spleen index, splenocyte proliferation, and cytokine secretion in vivo. These results indicate that okra polysaccharides may potentially serve as novel immunomodulators.

Chemical Constituents from the Aerial Parts of Isodon coetsa and their Cytotoxicity

Wei Zhao,Jian Xin Pu,Xue Du,Yong Zhao,Fei He,Hai Bo Zhang,Yong Bo Xue,Wei Lie Xiao,Han Dong Sun,Ying Li Wu,Guo Qiang Chen 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.12

Three new compounds (1-3), including a neolignan, a triterpenoid, and a diterpenoid, together with twenty known compounds (4-23), were isolated from the aerial parts of Isodon coetsa. Their structures and relative configurations were elucidated on the basis of spectroscopic data. Compounds 1, 3, 5-9, 11-13, 16-17, and 19-23 were evaluated for their cytotoxicity against HT-29, BEL-7402, and SK-OV-3 human tumor cell lines. Compound 7 showed significant inhibitory effects on all three types of cells, with IC50 values of 2.52, 3.06, 2.14 μM, respectively.