The posterior silk gland （PSG） of silkworm is an important organ where fibroin is synthesized and secreted exclusively. Because fibroin constitutes 75-80% of the silk filament, the mechanism governing fibroin secret...The posterior silk gland （PSG） of silkworm is an important organ where fibroin is synthesized and secreted exclusively. Because fibroin constitutes 75-80% of the silk filament, the mechanism governing fibroin secretion, quality and yield of cocoon can be elucidated by the study on the PSG. Using two-dimensional gel electrophoresis （2-DE） and image analysis system, the changes in the protein composition in the PSG cell were investigated on the day 1 （D1） and day 4 （D4） in the 5th instar stage from five different strains of silkworm （Bombyx mori）. While differences at protein level between days and strains were far less than those observed at the gene level using EST analysis. The change trends in protein composition from D1 to D4 were diverse among the different strains. The results suggest that the secretion of fibroin is regulated by multiple proteins. The site of regulation and the proteins responsible for the regulation vary with the strain, which leads to differences between strains in the capacity of fibroin secretion in the PSG cell.展开更多
目的系统分析中国成年人群中食物频率问卷(food frequency questionnaire,FFQ)的信效度研究现状,为进一步推广应用FFQ提供参考依据。方法基于中国知网、万方数据知识服务平台、维普数据库、PubMed、Embase,系统检索1992年至2021年12月...目的系统分析中国成年人群中食物频率问卷(food frequency questionnaire,FFQ)的信效度研究现状,为进一步推广应用FFQ提供参考依据。方法基于中国知网、万方数据知识服务平台、维普数据库、PubMed、Embase,系统检索1992年至2021年12月的所有中国成年人群FFQ信效度研究文献,文献筛查、评价和数据提取后进行Meta分析。结果最终纳入30篇文献,样本量范围为22-1623名。FFQ食物清单数目为25-172种,5项研究报告了针对FFQ建立相应的食物成分表以计算营养素摄入量,但大多数研究仍然缺乏FFQ设计、实施及数据处理标准化流程的详细说明。总体看,FFQ评估膳食因素的平均信度较好(合并效应值>0.4)。在效度检验中,FFQ对比24小时膳食回顾(24-hour dietary recall,24HR)的相关系数合并效应值:营养素为0.46(95%置信区间(confidence interval,CI):0.39-0.52),食物组为0.43(95%CI:0.36-0.50);对比膳食记录法(dietary record,DR):营养素为0.36(95%CI:0.30-0.42),食物组为0.45(95%CI:0.37-0.52)。FFQ食物清单数量、回忆时间框、研究设计质量、是否调整能量或校正个体内差异均可影响FFQ的效度结果。此外,单一水平看,营养素中维生素B1,食物组中薯类、禽肉、坚果、食用油和盐的测量有效性相对较差。结论中国成年人群FFQ设计及信效度研究结果存在一定差异,整体具有中等可接受的信效度水平,提示FFQ在大型人群研究中开展膳食评估具有良好的应用价值。同时FFQ应用的规范化标准流程仍然需要完善与统一,亟待更多的研究优化规范及推广使用。展开更多
文摘The posterior silk gland （PSG） of silkworm is an important organ where fibroin is synthesized and secreted exclusively. Because fibroin constitutes 75-80% of the silk filament, the mechanism governing fibroin secretion, quality and yield of cocoon can be elucidated by the study on the PSG. Using two-dimensional gel electrophoresis （2-DE） and image analysis system, the changes in the protein composition in the PSG cell were investigated on the day 1 （D1） and day 4 （D4） in the 5th instar stage from five different strains of silkworm （Bombyx mori）. While differences at protein level between days and strains were far less than those observed at the gene level using EST analysis. The change trends in protein composition from D1 to D4 were diverse among the different strains. The results suggest that the secretion of fibroin is regulated by multiple proteins. The site of regulation and the proteins responsible for the regulation vary with the strain, which leads to differences between strains in the capacity of fibroin secretion in the PSG cell.
