Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings,we analyzed two planar computational models and three 3D computational models with cambered co...Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings,we analyzed two planar computational models and three 3D computational models with cambered corrugation based on the finite element method.It is shown that the vein size in different zones is proportional to the magnitude of the vein internal force when the wing structure is subjected to uniform out-of-plane transverse loading.The membrane contributes little to the flexural stiffness of the planar wing models,while exerting an immense impact upon the stiffness of the 3D wing models with cambered corrugation.If a lumped mass of 10% of the wing is fixed on the leading edge close to the wing tip,the wing fundamental fre-quency decreases by 10.7%～13.2%;if a lumped mass is connected to the wing via multiple springs,the wing fundamental fre-quency decreases by 16.0%～18.0%.Such decrease in fundamental frequency explains the special function of the wing pterostigma in alleviating the wing quivering effect.These particular features of dragonfly wings can be mimicked in the design of new-style reticulately stiffening thin-walled roof systems and flapping wings in novel intelligent aerial vehicles.展开更多
Mitogen-activated protein kinase （MAPK） cascades are universal signal transduction modules present in all eukaryotes. In plants, MAPK cascades were shown to regulate cell division, developmental processes, stress re...Mitogen-activated protein kinase （MAPK） cascades are universal signal transduction modules present in all eukaryotes. In plants, MAPK cascades were shown to regulate cell division, developmental processes, stress responses, and hormone pathways. The subgroup A of Arabidopsis MAPKs consists of AtMPK3, AtMPK6, and AtMPK10. AtMPK3 and AtMPK6 are activated by their upstream MAP kinase kinases （MKKs） AtMKK4 and AtMKK5 in response to biotic and abiotic stress. In addition, they were identified as key regulators of stomatal development and patterning. AtMPKIO has long been considered as a pseudo-gene, derived from a gene duplication of AtMPK6. Here we show that AtMPKIO is expressed highly but very transiently in seedlings and at sites of local auxin maxima leaves. MPK10 encodes a functional kinase and interacts with the upstream MAP kinase kinase （MAPKK） AtMKK2. mpklO mutants are delayed in flowering in long-day conditions and in continuous light. Moreover, cotyledons of mpk10 and mkk2 mutants have reduced vein complexity, which can be reversed by inhibiting polar auxin transport （PAT）. Auxin does not affect AtMPKIO expression while treatment with the PAT inhibitor HFCA extends the expression in leaves and reverses the mpklO mutant phenotype. These results suggest that the AtMKK2-AtMPK10 MAPK module regulates venation complexity by altering PAT efficiency.展开更多
基金Project supported by the National Natural Science Foundation of China(No. 50408022)the Visiting Scholarship from the Future Academic Star Project of Zhejiang Universitythe Scientific Research Foundation for the Returned Overseas Chinese Scholars,MOE and Zhejiang Province,China
文摘Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings,we analyzed two planar computational models and three 3D computational models with cambered corrugation based on the finite element method.It is shown that the vein size in different zones is proportional to the magnitude of the vein internal force when the wing structure is subjected to uniform out-of-plane transverse loading.The membrane contributes little to the flexural stiffness of the planar wing models,while exerting an immense impact upon the stiffness of the 3D wing models with cambered corrugation.If a lumped mass of 10% of the wing is fixed on the leading edge close to the wing tip,the wing fundamental fre-quency decreases by 10.7%～13.2%;if a lumped mass is connected to the wing via multiple springs,the wing fundamental fre-quency decreases by 16.0%～18.0%.Such decrease in fundamental frequency explains the special function of the wing pterostigma in alleviating the wing quivering effect.These particular features of dragonfly wings can be mimicked in the design of new-style reticulately stiffening thin-walled roof systems and flapping wings in novel intelligent aerial vehicles.
文摘Mitogen-activated protein kinase （MAPK） cascades are universal signal transduction modules present in all eukaryotes. In plants, MAPK cascades were shown to regulate cell division, developmental processes, stress responses, and hormone pathways. The subgroup A of Arabidopsis MAPKs consists of AtMPK3, AtMPK6, and AtMPK10. AtMPK3 and AtMPK6 are activated by their upstream MAP kinase kinases （MKKs） AtMKK4 and AtMKK5 in response to biotic and abiotic stress. In addition, they were identified as key regulators of stomatal development and patterning. AtMPKIO has long been considered as a pseudo-gene, derived from a gene duplication of AtMPK6. Here we show that AtMPKIO is expressed highly but very transiently in seedlings and at sites of local auxin maxima leaves. MPK10 encodes a functional kinase and interacts with the upstream MAP kinase kinase （MAPKK） AtMKK2. mpklO mutants are delayed in flowering in long-day conditions and in continuous light. Moreover, cotyledons of mpk10 and mkk2 mutants have reduced vein complexity, which can be reversed by inhibiting polar auxin transport （PAT）. Auxin does not affect AtMPKIO expression while treatment with the PAT inhibitor HFCA extends the expression in leaves and reverses the mpklO mutant phenotype. These results suggest that the AtMKK2-AtMPK10 MAPK module regulates venation complexity by altering PAT efficiency.
