To understand the mechanisms of starfish regeneration, the arms of adult starfish Asterias rollestoni Bell were amputated and their regeneration patterns and cellular mechanisms were studied.It was found that cells in...To understand the mechanisms of starfish regeneration, the arms of adult starfish Asterias rollestoni Bell were amputated and their regeneration patterns and cellular mechanisms were studied.It was found that cells in the outer epidermis and inner parietal peritoneum near the end of the stump began to dedifferentiate 4 d after amputation. The dedifferentiated cells in the outer epidermis proliferated,migrated to the wound site and formed a thickened pre-epidermis which would then re-differentiate gradually into ma-ture epidermis.The new parietal peritoneum formed on the coelomic side of wound might be from the curvely elongated parietal peritoneum, resulting from the dedifferentiated and proliferated cells by extension. Afterwards, the proliferated cells made the outer epidermis and inner parietal peritoneum invaginate into the interior dermis and formed blastema-like structures together with induced dedifferentiated dermal cells. Most interestingly, the arm regeneration in A. rollestoni was achieved synchronously by de novo arm-bud formation and growth, and arm-stump elongation. The crucial aspects of arm-bud formation included cell dedifferentiation, proliferation and migration, while those of arm-stump elongation included cell dedifferentiation, proliferation, invagination, and arm-wall-across blastema-like structure formation. The unique pattern and cellular mechanisms of amputated arm regeneration make it easier to understand the rapid regeneration process of adult starfish. This study may lay solid foundations for the research into mo-lecular mechanisms of echinoderm regeneration.展开更多
Through the analysis of 86 valid questionnaires and twice follow-up interviews connected with twice MBI-ESs for the three chosen participants, this study shows that： 1） The job burnout syndrome of English teachers i...Through the analysis of 86 valid questionnaires and twice follow-up interviews connected with twice MBI-ESs for the three chosen participants, this study shows that： 1） The job burnout syndrome of English teachers in secondary schools is not very serious; 2） There＇s no significant difference between male and female teachers, between teachers in junior and senior middle schools or between teachers in key and average schools, but teachers with more teaching experience can often find a sense of personal achievement; 3） The causes of English teachers＇ job burnout in secondary schools lie in external factors, such as unreasonable school policy, student-management pressure, exam pressure, etc. and internal factors, such as knowledge exhaustion, lacking self-adjustment, etc.展开更多
基金supported by the funds for Natural Science Research from the Bureau of Science and Technology of Qingdao(04-2-JZ-8)
文摘To understand the mechanisms of starfish regeneration, the arms of adult starfish Asterias rollestoni Bell were amputated and their regeneration patterns and cellular mechanisms were studied.It was found that cells in the outer epidermis and inner parietal peritoneum near the end of the stump began to dedifferentiate 4 d after amputation. The dedifferentiated cells in the outer epidermis proliferated,migrated to the wound site and formed a thickened pre-epidermis which would then re-differentiate gradually into ma-ture epidermis.The new parietal peritoneum formed on the coelomic side of wound might be from the curvely elongated parietal peritoneum, resulting from the dedifferentiated and proliferated cells by extension. Afterwards, the proliferated cells made the outer epidermis and inner parietal peritoneum invaginate into the interior dermis and formed blastema-like structures together with induced dedifferentiated dermal cells. Most interestingly, the arm regeneration in A. rollestoni was achieved synchronously by de novo arm-bud formation and growth, and arm-stump elongation. The crucial aspects of arm-bud formation included cell dedifferentiation, proliferation and migration, while those of arm-stump elongation included cell dedifferentiation, proliferation, invagination, and arm-wall-across blastema-like structure formation. The unique pattern and cellular mechanisms of amputated arm regeneration make it easier to understand the rapid regeneration process of adult starfish. This study may lay solid foundations for the research into mo-lecular mechanisms of echinoderm regeneration.
文摘Through the analysis of 86 valid questionnaires and twice follow-up interviews connected with twice MBI-ESs for the three chosen participants, this study shows that： 1） The job burnout syndrome of English teachers in secondary schools is not very serious; 2） There＇s no significant difference between male and female teachers, between teachers in junior and senior middle schools or between teachers in key and average schools, but teachers with more teaching experience can often find a sense of personal achievement; 3） The causes of English teachers＇ job burnout in secondary schools lie in external factors, such as unreasonable school policy, student-management pressure, exam pressure, etc. and internal factors, such as knowledge exhaustion, lacking self-adjustment, etc.
