The water snail Pomacea canaliculata retracts the discoidal and multi-layered operculum to protect the soft body from being attacked by predators,and releases it when threats lifted.However,the duration of the opercul...The water snail Pomacea canaliculata retracts the discoidal and multi-layered operculum to protect the soft body from being attacked by predators,and releases it when threats lifted.However,the duration of the operculum retraction is usually less than that of the operculum protraction.In this paper,we elucidate the biological compliant mechanism of the operculum.By using confocal laser scanning microscopy,we find that the operculum has compliant sandwiched layers between hard layers.The layered structure results in a compliant mechanism with a bidirectional stiffness for the locking and unlocking processes of the operculum.A mathematical model is derived to rationalize the bidirectional stiffness mechanism of the operculum.In addition,we carry out the experiments on the locking and unlocking processes.The experimental results show that the locking tension is about two-fifths of the unlocking tension of the operculum.Moreover,based on the mechanical properties of the operculum with the layered structure,we designed an operculum-inspired structure,which may have a variety of potential applications in combined driving patterns.展开更多
文摘目的研究茶黄素调节Snail/Slug信号通路对口腔鳞癌(OSCC)细胞增殖、凋亡和上皮间质转化的影响。方法采用MTT法检测25、50、100、150、175 mg/L茶黄素处理的人OSCC细胞SCC-25存活率,筛选出茶黄素的合适作用浓度。体外培养SCC-25细胞并构建OSCC移植瘤模型,分为对照组、茶黄素低剂量组、茶黄素高剂量组、茶黄素高剂量+空载组、茶黄素高剂量+Snail过表达组。采用实时荧光定量PCR与免疫印迹检测各组细胞Snail、Slug表达;采用MTT法与流式细胞术分别检测各组细胞增殖、凋亡;采用细胞划痕与Transwell侵袭实验分别检测各组SCC-25细胞迁移、侵袭;采用免疫印迹检测各组SCC-25细胞凋亡及上皮间质转化相关蛋白表达;检测各组裸鼠肿瘤体积、肿瘤质量。结果与对照组相比,茶黄素低剂量组、茶黄素高剂量组细胞存活率、迁移率、侵袭数、Snail mRNA及蛋白表达、Slug m RNA及蛋白表达、Bcl-2、N-cadherin蛋白表达、裸鼠肿瘤质量及体积均降低(P<0.05),细胞凋亡率、Bax、ZO-1及E-cadherin蛋白表达均升高(P<0.05),高剂量茶黄素作用更强。与茶黄素高剂量组相比,茶黄素高剂量+空载组各指标差异无统计学意义(P>0.05);过表达Snail可逆转茶黄素对细胞及裸鼠各指标的影响。结论茶黄素可下调Snail/Slug通路蛋白表达,从而抑制OSCC细胞的上皮间质转化、增殖、迁移及侵袭,促使其凋亡,并可延缓裸鼠移植瘤的生长。
基金supported by National Natural Science Foundation of China(Grant No.52275298,and No.51905556)Pandeng Plan of Guangdong Province(Grant No.52910001,and No.11220004)Shenzhen Science and Technology Program(Grant No.GXWD2021B03,No.20220817165030002,and No.ZDSYS20210623091808026).
文摘The water snail Pomacea canaliculata retracts the discoidal and multi-layered operculum to protect the soft body from being attacked by predators,and releases it when threats lifted.However,the duration of the operculum retraction is usually less than that of the operculum protraction.In this paper,we elucidate the biological compliant mechanism of the operculum.By using confocal laser scanning microscopy,we find that the operculum has compliant sandwiched layers between hard layers.The layered structure results in a compliant mechanism with a bidirectional stiffness for the locking and unlocking processes of the operculum.A mathematical model is derived to rationalize the bidirectional stiffness mechanism of the operculum.In addition,we carry out the experiments on the locking and unlocking processes.The experimental results show that the locking tension is about two-fifths of the unlocking tension of the operculum.Moreover,based on the mechanical properties of the operculum with the layered structure,we designed an operculum-inspired structure,which may have a variety of potential applications in combined driving patterns.