Surface sediments from the Chukchi Sea and adjacent arctic deep sea were investigated for organic carbon and nitrogen isotopes （in δ13Corg and δ15Norg） as well as biogeni＇c silica （BSiO2）. δ13Corg and δ15Norg...Surface sediments from the Chukchi Sea and adjacent arctic deep sea were investigated for organic carbon and nitrogen isotopes （in δ13Corg and δ15Norg） as well as biogeni＇c silica （BSiO2）. δ13Corg and δ15Norg values of surface sediments in the study area fall between the end-member values of marine and terrestrial organic matter from the surrounding lands and seas, their variations reflect the changes of marine productivity and terrestrial supply in the study area. BSiO2 shows a similar distribution pattern with δ13Corg and δ15Norg, and can be used as an indicator of marine productivity. In the central-west Chukchi Sea and the Chukchi Rise, sediments have higher δ13Corg, δ15Norg and BSiO2 values, indicating the region has high marine productivity influenced by the nutrient-rich branches of the Pacific waters. In the coastal zone off northwestern Alaska, δ13Corg and δ15Norg values become lighter, indicating a weakening marine productivity and an increasing terrigenous supply due to the effects of the least nutrient-rich branch of the Pacific waters. In the north and the northeast of the study area （including the Chukchi Plateau, the Canada Basin and the Beaufort shelf）, δ13Corg, δ15Norg and BSiO2 have the lowest values, and the terrigenous organic matter becomes dominant in surface sediments because this region has the longest ice-covered duration, the least nutrient-rich seawater and the increasing supply of terrestrial materials from the Mackenzie River and the northern Alaska under the action of the clockwise Beaufort gyre. Because the subarctic Pacific waters are continuously discharged into the central basin of the Arctic Ocean through the study area, the nutrient pool in the Chukchi Sea can be considered as a typical open system, the ratio of δ15Norg to BSiO2 content show some tracers that the level of nutrient utilization is contrary to nutrient supply and marine productivity formed in seawater.展开更多
The in vitro maturation, fertilization and development of bovine ovary oocytes in two differentcultural systems A and B were studied under the conditions of 38.5℃,5%CO2,95%air and 100%humidity.The maturation rates we...The in vitro maturation, fertilization and development of bovine ovary oocytes in two differentcultural systems A and B were studied under the conditions of 38.5℃,5%CO2,95%air and 100%humidity.The maturation rates were 94.5%and 91.3%,respectively,and the difference wasextremely significant.Frozen semen were thawed and sperm were capacitated with three kinds ofcapacitation agents for fertilization.The pronucleus rates were 76%,65%-68%and 62%respectively.The rates of embryos developed to morula and blastocyst were 19%,16% and 17%respectively.The developmental rates of embryos cocultured with bovine oviductal epithelium cellsand bovine granulosa cells were 25% and 23.4% respectively,with no significant difference. Freshembryos were transplanted into 15 recipicns,and three of them were pregnant and calves were bornin 1990 and 1991.The pregnant rate was 20%.The emryos developed faster before 8-cell stage andslower after 8-cell stage,in vitro than in vivo.展开更多
基金the National Natural Science Foundation of China under contract Nos 40506004 and 40431002.
文摘Surface sediments from the Chukchi Sea and adjacent arctic deep sea were investigated for organic carbon and nitrogen isotopes （in δ13Corg and δ15Norg） as well as biogeni＇c silica （BSiO2）. δ13Corg and δ15Norg values of surface sediments in the study area fall between the end-member values of marine and terrestrial organic matter from the surrounding lands and seas, their variations reflect the changes of marine productivity and terrestrial supply in the study area. BSiO2 shows a similar distribution pattern with δ13Corg and δ15Norg, and can be used as an indicator of marine productivity. In the central-west Chukchi Sea and the Chukchi Rise, sediments have higher δ13Corg, δ15Norg and BSiO2 values, indicating the region has high marine productivity influenced by the nutrient-rich branches of the Pacific waters. In the coastal zone off northwestern Alaska, δ13Corg and δ15Norg values become lighter, indicating a weakening marine productivity and an increasing terrigenous supply due to the effects of the least nutrient-rich branch of the Pacific waters. In the north and the northeast of the study area （including the Chukchi Plateau, the Canada Basin and the Beaufort shelf）, δ13Corg, δ15Norg and BSiO2 have the lowest values, and the terrigenous organic matter becomes dominant in surface sediments because this region has the longest ice-covered duration, the least nutrient-rich seawater and the increasing supply of terrestrial materials from the Mackenzie River and the northern Alaska under the action of the clockwise Beaufort gyre. Because the subarctic Pacific waters are continuously discharged into the central basin of the Arctic Ocean through the study area, the nutrient pool in the Chukchi Sea can be considered as a typical open system, the ratio of δ15Norg to BSiO2 content show some tracers that the level of nutrient utilization is contrary to nutrient supply and marine productivity formed in seawater.
文摘The in vitro maturation, fertilization and development of bovine ovary oocytes in two differentcultural systems A and B were studied under the conditions of 38.5℃,5%CO2,95%air and 100%humidity.The maturation rates were 94.5%and 91.3%,respectively,and the difference wasextremely significant.Frozen semen were thawed and sperm were capacitated with three kinds ofcapacitation agents for fertilization.The pronucleus rates were 76%,65%-68%and 62%respectively.The rates of embryos developed to morula and blastocyst were 19%,16% and 17%respectively.The developmental rates of embryos cocultured with bovine oviductal epithelium cellsand bovine granulosa cells were 25% and 23.4% respectively,with no significant difference. Freshembryos were transplanted into 15 recipicns,and three of them were pregnant and calves were bornin 1990 and 1991.The pregnant rate was 20%.The emryos developed faster before 8-cell stage andslower after 8-cell stage,in vitro than in vivo.
