In vitro maturation of oocytes derived from the brown bear (Ursus arctos)

This study was conducted to determine whether meiotic maturation could be induced in ovarian oocytes from the American brown bear (Ursus arctos), a model for gamete "rescue" techniques for endangered ursids. The bears were euthanized, and their ovaries were transported to the laboratory within 4 h. The mean ovarian size was 2.4 x 1.8 cm (range: 2.0-3.3 x 1.5-2.2 cm). The ovaries obtained from the 2 brown bears yielded 97 oocytes (48.5/female), and 88 (90.7%) of them were morphologically classified as normal quality. Oocytes were in vitro matured at 38.5 C in 5% CO2 for 24 or 48 h in TCM-199 supplemented with 10% FBS, 1 microg/ml estradiol-17beta, and 10 microg/ml FSH. In Exp. 1, morphologic evaluation of matured oocytes was conducted by measuring the diameters of oocytes with a zona pellucida (ZP) or cytoplasm without a ZP. In Exp. 2, activation was induced by applying two 20 microsec DC pulses of 2.0 kV/cm delivered by an Electro Cell Fusion Generator. The activated oocytes were cultured in TCM-199 containing 2 mM of 6-dimethylaminopurine for 4 h, in Charles Rosenkrans (CR) 1 for 3 days and the in CR2 for another 4 days. The diameters of the matured bear oocytes with a ZP and with cytoplasm without a ZP (161.8 +/- 6.0 and 135.3 +/- 7.5 microm, respectively) were significantly (P<0.05) larger than those of bovine oocytes (150.7 +/- 4.9 and 118.7 +/- 7.5 microm). The maturation rates of the bear oocytes were 17.6 and 59.4% at 24 and 48 h of in vitro maturation, the percentage of activated oocytes that developed to the 2 or 4-cell stage was 31.6%; however, no blastocysts were observed. These results indicate that bear oocytes can develop to metaphase II in an in vitro culture system and that activated oocytes can develop to the 2 or 4-cell stages.     

Supracolloidal reaction kinetics of Janus spheres

Clusters in the form of aggregates of a small number of elemental units display structural, thermodynamic, and dynamic properties different from those of bulk materials. We studied the kinetic pathways of self-assembly of "Janus spheres" with hemispherical hydrophobic attraction and found key differences from those characteristic of molecular amphiphiles. Experimental visualization combined with theory and molecular dynamics simulation shows that small, kinetically favored isomers fuse, before they equilibrate, into fibrillar triple helices with at most six nearest neighbors per particle. The time scales of colloidal rearrangement combined with the directional interactions resulting from Janus geometry make this a prototypical system to elucidate, on a mechanistic level and with single-particle kinetic resolution, how chemical anisotropy and reaction kinetics coordinate to generate highly ordered structures.     

论宋代的特奏名制度

宋代科举中的特奏名制度,是中国古代科举制度中一项特殊的制度,值得注意。自太祖后期到真宗朝后期,是特奏名制度逐渐形成的时期。随着特奏名人数的大幅增加,也显露了它的某些弊端,因而在士大夫中要求废除特奏名制度的呼声不断高涨。但终宋之世,特奏名制度仍存而不废,其主要原因,除了最高统治者为贯彻重文抑武、牢笼士人的祖宗家法以外,特奏名本身所作出的某些贡献也是重要原因。     

Ultrathin single-crystalline silver nanowire arrays formed in an ambient solution phase

We report the synthesis of single-crystalline silver nanowires of atomic dimensions. The ultrathin silver wires with 0.4 nanometer width grow up to micrometer-scale length inside the pores of self-assembled calix[4]hydroquinone nanotubes by electro-/photochemical redox reaction in an ambient aqueous phase. The present subnanowires are very stable under ambient air and aqueous environments, unlike previously reported metal wires of approximately 1 nanometer diameter, which existed only transiently in ultrahigh vacuum. The wires exist as coherently oriented three-dimensional arrays of ultrahigh density and thus could be used as model systems for investigating one-dimensional phenomena and as nanoconnectors for designing nanoelectronic devices.     

A direct role for dual oxidase in Drosophila gut immunity

Because the mucosal epithelia are in constant contact with large numbers of microorganisms, these surfaces must be armed with efficient microbial control systems. Here, we show that the Drosophila nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme, dual oxidase (dDuox), is indispensable for gut antimicrobial activities. Adult flies in which dDuox expression is silenced showed a marked increase in mortality rate even after a minor infection through ingestion of microbe-contaminated food. This could be restored by the specific reintroduction of dDuox, demonstrating that this oxidase generates a unique epithelial oxidative burst that limits microbial proliferation in the gut. Thus, oxidant-mediated antimicrobial responses are not restricted to the phagocytes, but rather are used more broadly, including in mucosal barrier epithelia.     

Expression of messenger ribonucleic acid encoding for steroidogenic acute regulatory protein and enzymes, and luteinizing hormone receptor during the spring transitional season in equine follicles

The period of spring transition, from the anovulatory to the ovulatory season, is characterized in many mares by cyclical growth and regression of large dominant follicles. These follicles produce only low concentrations of estradiol and it is thought that acquisition of steroidogenic competence by large follicles during spring transition is prerequisite in stimulating LH prior to first ovulation. In situ hybridization was used to localize and quantify expression of factors that play a key role in follicular steroidogenesis: StAR, P450scc (CYP11A1), P450c17 (CYP17), P450arom (CYP19), and LH receptor (LHr). One ovary was obtained from mares on the day after detection of an actively growing 30 mm transitional anovulatory follicle (defined as the transitional follicle), and the remaining ovary was removed at the third estrus of the breeding season on the day after the preovulatory follicle reached 30 mm in diameter (defined as the preovulatory follicle). Messenger RNAs encoding StAR, CYP11A1, and CYP17 were detected only in theca cells and CYP19 mRNA was confined to the granulosa layer. There was significantly lower expression of mRNAs for the steroidogenic enzymes, StAR (P<0.001) and LHr (P<0.05) in transitional follicles than in preovulatory follicles. In conclusion, large equine follicles during spring transition have low levels of mRNA encoding steroidogenic enzymes, StAR and LHr which will contribute to the steroidogenic incompetence of dominant follicles during spring transition and their subsequent regression.     

Optimum temperature and salinity conditions for growth of green algae <Emphasis Type="Italic">Chlorella ellipsoidea</Emphasis> and <Emphasis Type="Italic">Nannochloris oculata</Emphasis>

ABSTRACT:   The effects of temperature and salinity on growth of green algae Chlorella ellipsoidea and Nannochloris oculata were determined to compare the optimum culture conditions. A four-temperature (15, 20, 25, and 30°C) × three-salinity (10, 20, and 30) factorial design with triplicates was applied. Specific growth rate (SGR), maximum density, and duration to reach maximum density of C. ellipsoidea were significantly affected by both temperature and salinity. The highest SGR was observed in C. ellipsoidea at 25°C and salinity 10, but the maximum density was very low. The highest maximum density was achieved in C. ellipsoidea at 15°C and 10. The slope constant of the linear relationship between semilogarithmic growth of C. ellipsoidea and day of culture was highest at 15°C and 10. The SGR and duration to reach maximum density of N. oculata were significantly affected by both temperature and salinity. However, maximum density of N. oculata was significantly affected by temperature, but not salinity. The highest maximum density was achieved in N. oculata at 25°C and 30, but SGR was significantly lower than that of N. oculata at 25°C and 10. The slope constant of the linear relationship between semilogarithmic growth of N. oculata and day of culture was highest at 25°C and 30. Based on these results, the condition of 15°C and salinity 10 seemed to be optimal for maximum density of C. ellipsoidea , and the condition of 25°C and 10 and 30 for SGR and maximum density for N. oculata , respectively.     

Effect of dietary inclusion of various sources of green tea on growth,body composition and blood chemistry of the juvenile olive flounder, <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

This study was performed to determine the effect of the dietary inclusion of various sources of green tea on growth, body composition and blood chemistry of the olive flounder. Twenty-five juvenile fish were distributed into each of 15 180 l flow-through tanks. Five experimental diets with triplicates were prepared: control, raw leaves, dry leaves, by-product and extract. The 5% various sources (raw leaves, dry leaves and by-product) of green tea were included in the experimental diets at the expense of 5% wheat flour. The extract was diluted with water and mixed with the ingredients to maintain 5% green tea at the same concentration as in the other diets. Weight gain and specific growth rate of fish fed the control diet and experimental diet containing extract were higher than those of fish fed the diets containing raw and dry leaves and by-product. Feed and protein efficiency ratio for fish fed the control diet and diet containing extract was higher than for fish fed the diets containing raw leaves and by-product. The level of low-density lipoprotein (LDL) cholesterol of fish fed the control diet was higher than that of fish fed the other diets containing various sources of green tea. The glutamic oxaloacetic transaminase (GPT) concentration of fish fed the diets containing raw leaves and extract was lower than that of fish fed the control diet. Crude lipid content of liver in fish fed the control diet was higher than that in fish fed the diets containing raw and dry leaves and by-product but was not significantly different from that of fish fed the diet containing extract. Dietary inclusion of extract was the most effective way to improve growth and feed utilization of the olive flounder among the various sources of green tea, and all sources of green tea were effective in lowering serum LDL cholesterol and GPT of the fish.