Enrichment of Y‐Chromosome‐Bearing Bull Spermatozoa by Swim‐up Through a Column

With the advancement of assisted reproductive biotechnologies, preselecting the sex of offspring has become an important goal for cattle and other livestock breeding as well as for research. The aim of this study was to investigate the feasibility of producing enriched pools of X‐ or Y‐chromosome‐bearing sperm by vertical swim‐up through a long, narrow column. Sperm recovered from the top portion of the column was predominantly Y‐bearing (60%, p < 0.05), which were capable of fertilizing matured oocytes and produce significantly more male embryos compared with standard swim‐up protocol.     

补饲马铃薯藤对山羊生长性能、消化率和胴体特征的影响

本研究旨在探讨马铃薯藤饲喂水平对山羊生长性能、养分消化率和胴体特征的影响。试验将平均初始体重为（14.42±0.24）kg的40头山羊随机分为4组,每组5个重复,每个重复2头。T1组仅饲喂干草,T2组饲喂干草+100%马铃薯藤,T3组饲喂干草+50%马铃薯藤+50%浓缩料,T4组饲喂100%浓缩料。在为期10周的饲养试验后屠宰,分析胴体特征。结果：T2～T4组山羊的末重、增重、日增重和饲料效率显著高于T1组（P＜0.05）,其中T1组山羊的日增重和增重均表现出负增长。T2～T4组山羊的干物质、有机物、粗蛋白质和代谢能摄入量均显著高于T1组（P＜0.05）,但T2和T3组山羊中性洗涤纤维摄入量显著高于T1和T4组（P＜0.05）。T2、T3和T4组山羊干物质和有机物表观消化率显著高于T1组（P＜0.05）,T4组山羊粗蛋白表观消化率显著高于T1和T2组（P＜0.05）。T2、T3和T4组山羊屠体重、热胴体重、眼肌面积、可食用内脏和不可食用内脏重量均显著高于T1组（P＜0.05）。T3组山羊的屠宰率显著高于其他组（P＜0.05）。结论：在干草为基础的日粮中添加马铃薯藤可以提高山羊采食量、饲料转换率、养分消化率、屠宰率和胴体特征。 [关键词]马铃薯藤|山羊|生长性能|消化率|胴体特征     

Mercury accumulation trends in Florida Everglades and Savannas Marsh flooded soils

Global and regional increases in atmospheric mercury (Hg) concentrations have previously been identified as the cause of increased mercury accumulation rates in north temperate lakes in Sweden, Wisconsin, and Minnesota. Atmospheric deposition can often account for elevated Hg concentrations in fish from these systems. Mercury levels in sportfish collected from some areas of the Florida Everglades and Savannas Marsh exceed limits that are acceptable for human consumption. Forty five soil cores and soil grab samples were retrieved from the Everglades and Savannas Marsh wetlands. Eighteen sediment cores were dated radiochemically with²¹⁰Pb and¹³⁷Cs using γ-ray spectroscopy to determine modern and historic mercury accumulation rates for these subtropical wetland systems. Recent (“post-1985”) Hg accumulation rates averaged 53 μg m^?2 y^?1 (23 to 141, n=18) corresponding to an average rate increase of 4.9 times (1.6 to 19.1) over those observed around the turn of the century. This accumulation seems to result more from either global or regional atmospheric deposition rather than from lateral transport via overlying surface water. The trends for mercury accumulation match those reported for lakes in Sweden and the northern United States, even though these systems are distinctly different in their climate, vegetational composition, and location. We provide the first data on accumulation of mercury in subtropical wetland systems, and demonstrate the feasibility of radiochemical dating of wetland sediment.     

大比例尺地面数字化测图初试

大比例尺地面数字化测图是一种高效率的作业方式,它可在传统测量方式基础上提高效率几倍甚至几十倍。其基本硬件配置包括全站仪、电子记录手簿、计算机及数字绘图仪等。软件包括野外电子记录手簿和计算机自动仪成图系统。     

The influence of allogeneic cells on the human T and B cell repertoire

Clinical transplantation is often complicated by rejection episodes, in which the immune system of the recipient reacts to the foreign transplantation (HLA) antigens on the graft. This immune response includes humoral and cellular components. In the first, B lymphocytes form antibodies to the HLA alloantigens. In the second, CD8+ T lymphocytes recognize and react to HLA class I antigens, and CD4+ T cells react to HLA class II antigens. The frequency and severity of these rejection episodes can be diminished by immunosuppressive drugs, HLA matching between donor and recipient, and immune modulation by blood transfusion. Effective HLA matching between donor and recipient is not always possible and often not necessary. Insight into the factors that influence the T and B cell repertoire after blood transfusion might lead to new approaches to improve graft survival.