Showing papers by "Ocean University of China published in 2005"

Caspase family proteases and apoptosis.

Abstract: Apoptosis, or programmed cell death, is an essential physiological process that plays a critical role in development and tissue homeostasis. The progress of apoptosis is regulated in an orderly way by a series of signal cascades under certain circumstances. The caspase-cascade system plays vital roles in the induction, transduction and amplification of intracellular apoptotic signals. Caspases, closely associated with apoptosis, are aspartate-specific cysteine proteases and members of the interleukin-1beta-converting enzyme family. The activation and function of caspases, involved in the delicate caspase-cascade system, are regulated by various kinds of molecules, such as the inhibitor of apoptosis protein, Bcl-2 family proteins, calpain, and Ca2+. Based on the latest research, the members of the caspase family, caspase-cascade system and caspase-regulating molecules involved in apoptosis are reviewed.

A model for the diffuse attenuation coefficient of downwelling irradiance

Abstract: [1] The diffuse attenuation coefficient for downwelling irradiance (Kd) is an important parameter for ocean studies. For the vast ocean the only feasible means to get fine-scale measurements of Kd is by ocean color remote sensing. At present, values of Kd from remote sensing are estimated using empirical algorithms. Such an approach is insufficient to provide an understanding regarding the variation of Kd and contains large uncertainties in the derived values. In this study a semianalytical model for Kd is developed based on the radiative transfer equation, with values of the model parameters derived from Hydrolight simulations using the averaged particle phase function. The model is further tested with data simulated using significantly different particle phase functions, and the modeled Kd are found matching Hydrolight Kd very well (∼2% average error and ∼12% maximum error). Such a model provides an improved interpretation about the variation of Kd and a basis to more accurately determine Kd (especially using data from remote sensing).

Diffuse attenuation coefficient of downwelling irradiance: An evaluation of remote sensing methods

Abstract: coastal waters, with Kd(490) ranging from � 0.04 to 4.0 m � 1 . The derived values are compared with the data calculated from in situ measurements of the vertical profiles of downwelling irradiance. The comparisons show that the two standard methods produced satisfactory estimates of Kd(l) in oceanic waters where attenuation is relatively low but resulted in significant errors in coastal waters. The newly developed semianalytical method appears to have no such limitation as it performed well for both oceanic and coastal waters. For all data in this study the average of absolute percentage difference between the in situ measured and the semianalytically derived Kd is � 14% for l = 490 nm and � 11% for l = 443 nm.

Haemolysins in Vibrio species

Abstract: Many Vibrio species are pathogenic to humans, and/or marine vertebrates and invertebrates. The pathogenic species produce various virulence factors including enterotoxin, haemolysin, cytotoxin, protease, lipase, phospholipase, siderophore, adhesive factor and/or haemagglutinins. Haemolysin, which is an exotoxin that lyses erythrocyte membranes with the liberation of haemoglobin, is arguably the most widely distributed toxin among pathogenic vibrios and exerts various roles in the infection process. Haemolysins act on erythrocytes membranes thus lysing the cells which leads to the freeing up of the iron-binding proteins namely haemoglobin, transferrin and lactoferrin. This iron can then be picked up by various siderophores, and is subsequently taken up through receptors in the cell membrane. In many cases, the pore-forming activity of haemolysin is not restricted to erythrocytes, but extends to a wide range of other cell types including mast cells, neutrophils, and polymorphonuclear cells, and enhances virulence by causing tissue damage. There are four representative haemolysin families in Vibrio spp., including the TDH (thermostable direct haemolysin) family, the HlyA (E1 Tor haemolysin) family, the TLH (thermolabile haemolysin) family and the d-VPH (thermostable haemolysin) family. Some haemolysins, for example, TDH of Vibrio parahaemolyticus and HlyA of Vibrio cholerae have been studied extensively, and are closely associated with virulence. However, the role of some haemolysins, e.g. TLH and d-VPH are unclear, and await the outcome of further research. 2. INTRODUCTION

Linolenic Acid-Modified Chitosan for Formation of Self-Assembled Nanoparticles

Abstract: Chitosan was modified by coupling with linolenic acid through the 1-ethyl-3-(3-dimethylaminopropyyl)carbodiimide-mediated reaction The degree of substitution was measured by 1H NMR, and it was 18%, ie, 18 linolenic acids group per 100 anhydroglucose units The critical aggregation concentration (CAC) of the self-aggregate of hydrophobically modified chitosan was determined by measuring the fluorescence intensity of the pyrene as a fluorescent probe The CAC value in phosphate-buffered saline (PBS) solution (pH 74) was 5 × 10-2 mg/mL The average particle size of self-aggregates of hydrophobically modified chitosan in PBS solution (pH 74) was 2108 nm with a unimodal size distribution ranging from 100 to 500 nm A transmission electron microscopy study showed that the formation of near spherical shape nanoparticles had enough structural integrity The loading ability of hydrophobically modified chitosan (LA-chitosan) was investigated by using bovine serum albumin (BSA) as a model protein Self-aggre

Novel synthesis of copper nanoparticles: influence of the synthesis conditions on the particle size

Abstract: This paper presents a novel method for the preparation of copper nanoparticles by reducing CuSO4 with hydrazine in ethylene glycol under microwave irradiation. The influences of reaction parameters such as molar ratios of N2H4?H2O /CuSO4 and NaOH/CuSO4, heating method and reaction temperature on the particle size and composition of powder were investigated by x-ray diffractometry (XRD), transmission electron microscopy (TEM) and particle size analysis. Well-dispersed copper nanopowder with a diameter of about 15?nm was obtained in the absence of a protective polymer.

Understanding the origins of interannual thermocline variations in the tropical Indian Ocean

Abstract: [1] Based on the data analysis of the 1000 hPa wind, SST and SSH anomalies, it is revealed that the atmospheric variations associated with Indian Ocean Dipole (IOD, or referred as Indian Ocean Zonal Dipole Mode, IOZDM) consist of a pair of anticyclones closely north and south of the equator with accompanying intense equatorial easterly anomalies, while the atmospheric variations related to El Nino/Southern Oscillation (ENSO) include a strong anticyclone in the southeastern tropical Indian Ocean (TIO) at higher latitudes with strong along-shore wind anomalies near Java-Sumatra coast. The different atmospheric forcing patterns lead to the fact that oceanic thermocline variations associated with IOD/IOZDM are more closely confined to the region north of 10°S, while ENSO-induced thermocline variations are dominant south of 10°S.

Partial replacement of fishmeal by soybean meal in diets for juvenile cobia (Rachycentron canadum)

Abstract: An 8-week feeding experiment was conducted in floating cages (1.5 x 1.0 x 2.0 m) to determine the potential use of defatted soybean meal (roasted and solvent-extracted) as a partial replacement of fishmeal in the isonitrogenous (approximately 450 g kg(-1) CP crude protein) diet for juvenile cobia with an initial average weight of about 8.3 g. Diets were formulated to include 0, 100, 200, 300, 400, 500 and 600 g kg(-1) (diets D0, D10, D20, D30, D40, D50 and D60, respectively) of fishmeal protein being substituted by defatted soybean meal without methionine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fishmeal protein was increased from 400 g kg(-1) to 500 g kg(-1), and the D60 diet was the lowest in all groups. These results indicate that up to 400 g kg(-1) of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by the replacement level of fishmeal protein being substituted by defatted soybean meal, when the replacement level of fishmeal protein was 200 g kg(-1) (diet, D20), FCR was the lowest and PER was the highest. There were no significant differences in the moisture, lipid, crude protein and ash content in whole body and muscle, while lipid content in liver increased as the dietary soybean meal replacement levels increased. There were significant differences in haemoglobin, haematocrit, red blood cell, plasma glucose and triglyceride concentration in fish fed diets with different soybean meal replacement levels. Results of this trial indicated that the optimum level of fishmeal protein replacement with defatted soybean meal, determined by quadratic regression analysis was 189.2 g kg(-1), on the basis of maximum weight gain.

Electrical and magnetic properties of polyaniline/Fe3O4 nanostructures

Abstract: We report on electrical and magnetic properties of polyaniline (PANI) nanotubes (∼150 nm in diameter) and PANI/Fe 3 O 4 nanowires (∼140 nm in diameter) containing Fe 3 O 4 nanoparticles with a typical size of 12 nm. These systems were prepared by a template-free method. The conductivity of the nanostructures is 10 −1 –10 −2 S/cm; and the temperature dependent resistivity follows a ln ρ∼T −1/2 law. The composites (6 and 20 wt% of Fe 3 O 4 ) show a large negative magnetoresistance compared with that of pure PANI nanotubes and a considerably lower saturated magnetization ( M s =3.45 emu/g at 300 K and 4.21 emu/g at 4 K) compared with the values measured from bulk magnetite ( M s =84 emu/g) and pure Fe 3 O 4 nanoparticles ( M s =65 emu/g). AC magnetic susceptibility was also measured. It is found that the peak position of the AC susceptibility of the nanocomposites shifts to a higher temperature (>245 K) compared with that of pure Fe 3 O 4 nanoparticles (190–200 K). These results suggest that interactions between the polymer matrix and nanoparticles take place in these nanocomposites.

Periphytic ciliate colonization: annual cycle and responses to environmental conditions

Abstract: Glass slides were used as artificial substrates for collecting periphytic ciliates from scallop-farming waters of Jiaozhou Bay near Qingdao (China) over a period of 1 yr. A total of 37 ciliate species, about half of which belong to the orders Hypotrichida and Cyrtophorida, were identi- fied using living observation and silver impregnation methods. Peaks of ciliate abundance and bio- mass occurred in November, mainly due to the suctorian Corynophrya lyngbyi, while sessile per- itrichs (especially Pseudovorticella sinensis, Zoothamnium duplicatum and Z. plumula) dominated the ciliate communities during August. Vagile ciliates had low abundance and biomass despite accounting for a large proportion of the species richness. Almost no typical periphytic ciliates were detected in the winter months (from January to March). Twelve dominant species showed clear succession over the year and were found to correlate with a variety of environmental variables. Uni- variate and multivariate analyses were performed in order to explore the relationship between ciliate community and environmental conditions (temperature, salinity, pH, dissolved inorganic nitrogen, soluble reactive phosphate, dissolved oxygen, chlorophyll a, turbidity). Diversity and evenness indices were found to be relatively independent of physico-chemical factors, whereas species richness and the ratio of biomass to abundance were strongly related to nutrients. Multivariate ana- lyses revealed that temperature, nutrients and salinity may best explain the changes in community structure of ciliates colonizing the glass slides.

A Barotropic Envelope Rossby Soliton Model for Block–Eddy Interaction. Part I: Effect of Topography

Abstract: A new forced envelope Rossby soliton model in an equivalent barotropic beta-plane channel is proposed to describe the interaction between an incipient block (planetary scale) and short synoptic-scale eddies This model is based on two assumptions, motivated by observations that (i) there exists a zonal scale separation between the planetary-scale and synoptic-scale waves and (ii) that the range of synoptic-scale zonal wavenumber is comparable to the planetary-scale zonal wavenumber These assumptions allow an analytical treatment The evolution of the planetary-scale block under the influence of synoptic-scale eddies is described by a forced nonlinear Schrodinger equation that is solved numerically, while the feedback of block development on the preexisting synoptic-scale eddies is derived analytically It is shown that the planetary-scale projection of the nonlinear interaction between synoptic-scale eddies is the most important contributor to the amplification and decay of the planetary-scale b