The highly speciose gekkonid genus Cnemaspis Strauch,1887 is polyphyletic,with three distantly related and geographically isolated clades from Africa,South Asia(SA),and Southeast Asia.At present,there are 85 known spe...The highly speciose gekkonid genus Cnemaspis Strauch,1887 is polyphyletic,with three distantly related and geographically isolated clades from Africa,South Asia(SA),and Southeast Asia.At present,there are 85 known species within SA Cnemaspis,although the number continues to increase rapidly with focused surveys and rigorous taxonomic work.Recent studies have provided valuable insights into the diversity and evolutionary history of SA Cnemaspis;however,most of these studies lack sufficient sampling in the Western Ghats(WG),where the genus has its greatest diversity.We addressed this research gap by conducting extensive sampling across the WG and re-examining museum specimens,thus providing a systematic account of various extant Cnemaspis species along with their distribution and natural history.We described 12 new species and a southern WG endemic clade of SA Cnemaspis.Ten of the newly described species are endemic to the forests of the southern WG.We also identified 10 well-supported subclades that can be separated across morphological,geographic,and phylogenetic axes.A time-calibrated phylogeny and ancestral area reconstructions confirmed the Paleocene origin of SA Cnemaspis in the WG and provide insights into its evolutionary history and biogeography.The discovery of multiple endemic and deeply divergent lineages further highlights the evolutionary significance of the WG for lizards.展开更多
The low intrinsic growth capacity of neurons and an injury-induced inhibitory milieu are major contributo rs to the failure of sensory and motor functional recovery following spinal cord injury.Heat shock transcriptio...The low intrinsic growth capacity of neurons and an injury-induced inhibitory milieu are major contributo rs to the failure of sensory and motor functional recovery following spinal cord injury.Heat shock transcription factor 1(HSF1),a master regulator of the heat shock response,plays neurogenetic and neuroprotective roles in the damaged or diseased central nervous system.However,the underlying mechanism has not been fully elucidated.In the present study,we used a gecko model of spontaneous nerve regeneration to investigate the potential roles of gecko HSF1(gHSF1) in the regulation of neurite outgrowth and inflammatory inhibition of macrophages following spinal cord injury.gHSF1 expression in neurons and microglia at the lesion site increased dramatically immediately after tail amputation.gHSF1 ove rexpression in gecko primary neuro ns significantly promoted axonal growth by suppressing the expression of suppressor of cytokine signaling-3,and fa cilitated neuro nal survival via activation of the mitogen-activated extracellular signal-regulated kinase/extracellular regulated protein kinases and phosphatidylinositol 3-kinase/protein kinase B pathways.Furthermore,gHSF1 efficiently inhibited the macrophagemediated inflammatory response by inactivating 1kappa B-alpha/NF-kappaB signaling.Our findings show that HSF1 plays dual roles in promoting axonal regrowth and inhibiting leukocyte inflammation,and provide new avenues of investigation for promoting spinal co rd injury repair in mammals.展开更多
Reptiles are the most morphologically and physiologically diverse tetrapods,with the squamates having the most diverse habitats.Lizard is an important model system for understanding the role of visual ecology,phylogen...Reptiles are the most morphologically and physiologically diverse tetrapods,with the squamates having the most diverse habitats.Lizard is an important model system for understanding the role of visual ecology,phylogeny and behavior on the structure of visual systems.In this study,we compared three opsin genes(RH2,LWS and SWS1)among 49 reptile species to detect positively selected genes as well as amino acid sites.Our results indicated that visual opsin genes have undergone divergent selection pressures in all lizards and RH2 and LWS suffered stronger positive selection than SWS1.Twelve positively selected sites were picked out for RH2 and LWS.Moreover,many diagnostic sites were found between geckos and non-gecko lizards,most of which were located near the positively selected sites and some of them have already been reported to be responsible for significant shifts of the wavelength of maximum absorption(λ_(max)).The results indicated that the gecko lineage accelerated the evolution of these genes to adapt to the dim-light environment or nocturnality as well as the switch between nocturnality and diurnality.展开更多
Geckos can move quickly in various environments by efficiently controlling their complex adhesive toe pads.The locomotion behaviours observed in the attachment-detachment(A-D)cycle of their toe pads in response to cha...Geckos can move quickly in various environments by efficiently controlling their complex adhesive toe pads.The locomotion behaviours observed in the attachment-detachment(A-D)cycle of their toe pads in response to changes in their environment should be studied to understand the adaptive behavioural characteristics of such toe pads.The lack of systematic research on the entire A-D cycle,including the release,swing,contact,and adhesion stages,limits the comprehension of the adhesive locomotion mechanism.The A-D cycle of Gekko gecko that facilitates the foot locomotion on inclined and vertical surfaces was investigated to clarify the locomotion behaviours in different stages.Results show that the change trends of foot locomotor angles(yaw and pitch)during the entire A-D cycle remain unchanged in response to various substrates.The bending angles(fore 41°;hind 51°)and contact time percentages(fore 7.42%;hind 7.44%)in the contact stage as well as the forefoot angle ranges(yaw:163.09°;pitch:308.68°)in the A-D cycle also remain constant across all substrates.These invariant foot locomotion behaviours during the swing and contact stages suggest that the foot behaviours are weakly related to the forces acting on the foot,which change according to the environment.Furthermore,the forefoot and hindfoot have different anatomical structure and functional demands,thus,the angle range of forefoot locomotion is larger than that of hindfoot locomotion,and the pitch angle change trend of the forefoot is opposite to that of the hindfoot.The diverse and complex locomotion control of the adhesive toe pads for various environments is reduced by the consistent behaviours in the gecko’s A-D cycle,such as the constant postures in the swing and contact stages.This study provides insight into the adhesive locomotion mechanism of geckos and can facilitate further research on the effective design and control of adhesion robots.展开更多
Adhesion achieved through feet setae is fundamental for gecko agilely maneuvering.Although diverse hypotheses have been proposed,none of them thoroughly explains the setae function,implying a kind of hybrid-mechanism-...Adhesion achieved through feet setae is fundamental for gecko agilely maneuvering.Although diverse hypotheses have been proposed,none of them thoroughly explains the setae function,implying a kind of hybrid-mechanism-based adhesion in geckos.In addition to van der Waals interactions and capillary force,the electrostatic attraction that emerges from triboelectrification was suggested as a component of setae adhesion.Nevertheless,the contribution by electrostatic attraction to the total setae attachment is still controversial.In this study,we analyzed the occurrence of electrostatic attraction at gecko setae through experiments and model analyses.By touching the substrates with only~1/70th of the foot area,freely wall-climbing geckos developed tribocharge at their feet setae with a density of~277 pC/mm^(2),generating electrostatic attractions with a strength of~4.4 mN/mm^(2).From this perspective,the adhesion driven by triboelectrification could account for about 1%of total adhesion.Model analyses at spatula level indicated a similar result showing that the electrostatic force might account for~3%of the adhesion that facilitates wall-climbing in geckos.The low contribution of the electrostatic force partly explains why geckos always face difficulty in maneuvering onto those substrates(e.g.,teflon)where they could easily develop tribocharge but difficultly generate van der Waals force.However,long-range electrostatic forces may play other roles in a distance range where the van der Waals interaction cannot function.These findings not only add to our understanding of the mechanism of gecko adhesion,but also will help us advance gecko-inspired fibular adhesives.展开更多
Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to s...Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.展开更多
Soft actuators are inherently flexible and compliant,traits that enhance their adaptability to diverse environments and tasks.However,their low structural stiffness can lead to unpredictable and uncontrollable complex...Soft actuators are inherently flexible and compliant,traits that enhance their adaptability to diverse environments and tasks.However,their low structural stiffness can lead to unpredictable and uncontrollable complex deformations when substantial force is required,compromising their load-bearing capacity.This work proposes a novel method that uses gecko setae-inspired adhesives as interlayer films to construct a layer jamming structure to adjust the stiffness of soft actuators.The mechanical behavior of a single tilted microcylinder was analyzed using the energy method to determine the adhesion force of the adhesives.The gecko-inspired adhesive was designed under the guidance of the adhesion force model.Testing under various loads and directions revealed that the tilted characteristic of microcylinders can enhance the adhesion force in its grasping direction.The adhesive demonstrated excellent adhesion performance compared to other typical adhesives.A tunable stiffness actuator using gecko setae-inspired adhesives(TSAGA),was developed with these adhesives serving as interlayer films.The stiffness model of TSAGA was derived by analyzing its axial compression force.The results of stiffness test indicate that the adhesives serve as interlayer films can adjust the stiffness in response to applied load.TSAGA was compared with other typical soft actuators in order to evaluate the stiffness performance,and the results indicate that TSAGA exhibits the highest stiffness and the widest tunable stiffness range.This demonstrates the superior performance of the setae-inspired adhesives as interlayer films in terms of stiffness adjustment.展开更多
A new species of gekkonid,Gekko liui sp.nov.,is described based on six specimens from Dazhou Island,Wanning City,Hainan,China.This new species is distinguished from its congeners by significant genetic divergence(>...A new species of gekkonid,Gekko liui sp.nov.,is described based on six specimens from Dazhou Island,Wanning City,Hainan,China.This new species is distinguished from its congeners by significant genetic divergence(>4.6% in the mitochondrial ND2 gene) and morphological characters,including a small body size(SVL 48.92– 56.67 mm,n = 6),nares in contact with rostral scale,37–42 interorbital scales between anterior corners of the eyes,140–148 ventral scales from mental to cloacal slit,103–118 midbody scale rows,34– 39 ventral scale rows,10–11 subdigital lamellae on the first toe and 12–13 on the fourth toe,webbing present in the fingers and toes,with tubercles on the dorsal surface of the tail,20–23 precloacal pores in males,and dorsal surface of body with six or seven large dark and brown bicolor bands between the nape and sacrum.The discovery of this new species brings the number of Gekko(subgenus Japonigekko) species in China to 23 and in Hainan Province to 4.展开更多
The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deci...The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.展开更多
Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein...Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein-coding, 2 ribosomal and 22 transfer RNA genes. The mt genome of Gekko is similar to most of the vertebrates in gene components, order, orientation, tRNA structures, low percentage of guanine and high percentage of thymine, and skews of base GC and AT. Base A was preferred at third codon positions for protein genes is similar to amphibians and fishes rather than amnion vertebrates. The standard stop codes (TAA) present only in three protein genes, less than those of most vertebrates. Transfer RNA genes range in length from 63 to 76 nt, their planar structure present characteristic clover leaf, except for tRNA-Cys and tRNA-Ser (AGY) because of lacking the D arm.展开更多
Karst habitats are hotspots of diversity and endemism. Their naturally fragmented distributions across broad geographic landscapes have led to the complex array of smaller evolutionary ecosystems that present unique c...Karst habitats are hotspots of diversity and endemism. Their naturally fragmented distributions across broad geographic landscapes have led to the complex array of smaller evolutionary ecosystems that present unique challenges from a conservation perspective.Comprehensivebiodiversity assessments of karst habitats have revealed that these ecosystems contain an almost unparalleled level of endemism, and many site-restricted species remain undescribed, thus posing considerable challenges for effective conservation management.Small rock-dwelling species, such as geckos, may be particularly prone to such isolation. In this paper, we discuss one such genus, i.e.,Hemiphyllodactylus, and explore its diversity across karst landforms in Yunnan Province, southwestern China. Based on morphological and genetic data, we describe two new species of Hemiphyllodactylus from karst habitats in Simao District and Yanshan County. A phylogenetic tree for Hemiphyllodactylus was constructed using 1?039 base pairs(bp) of the mitochondrial NADH dehydrogenase subunit 2 gene(ND2). The Simao and Yanshan specimens can be distinguished from all other congeners within their respective subclades based on uncorrected genetic pairwise distances greater than 6.3% and 4.3%respectively, as well as significant morphological differences. The discovery and description of these two new species brings the total number of described Hemiphyllodactylus species in China to 14and indicates many more undescribed species from unsurveyed karst regions await discovery.Our findings suggest that karst ecosystems in Yunnan support a higher diversity of Hemiphyllodactylus than previously known.This study also highlights the importance of karst ecosystems as refugia for sitespecific endemic species and the need for heightened conservation efforts.展开更多
Polyacrylamide gel electrophoreses for malate dehydrogenase (Mdh) and beta-esterase (β-Est) isoenzymes were conducted for biochemical differentiation between two Stenodactylus gekkonid species inhabiting North Sinai ...Polyacrylamide gel electrophoreses for malate dehydrogenase (Mdh) and beta-esterase (β-Est) isoenzymes were conducted for biochemical differentiation between two Stenodactylus gekkonid species inhabiting North Sinai of Egypt. Total lipids and proteins of liver and muscle tissues in both species were also analyzed. A total of three Mdh isoforms were recorded in the analysis, in which the activity of Mdh-2 and Mdh-3 seemed to be higher in S. petrii than in S. sthenodactylus. This high activity could be supported by the significant increase in the total lipids and proteins in liver and muscle tissues of the species. It may thus be reasonable to suppose that S. petrii is more active, energetic and adaptable in the desert habitat than S. sthenodactylus. β-Est showed six fractions in S. petrii and only one fraction in S. sthenodactylus. It is therefore noticeable that β-Est is more highly expressed in S. petrii than in S. sthenodactylus.展开更多
基金This study was supported by the Critical Ecosystem Partnership Fund(Western Ghats)DBT-IISc Partnership Programme and Ministry of Environment,Forests,and Climate Change(MoEFCC)Singinawa Conservation Foundation,and Rufford Small Grant。
文摘The highly speciose gekkonid genus Cnemaspis Strauch,1887 is polyphyletic,with three distantly related and geographically isolated clades from Africa,South Asia(SA),and Southeast Asia.At present,there are 85 known species within SA Cnemaspis,although the number continues to increase rapidly with focused surveys and rigorous taxonomic work.Recent studies have provided valuable insights into the diversity and evolutionary history of SA Cnemaspis;however,most of these studies lack sufficient sampling in the Western Ghats(WG),where the genus has its greatest diversity.We addressed this research gap by conducting extensive sampling across the WG and re-examining museum specimens,thus providing a systematic account of various extant Cnemaspis species along with their distribution and natural history.We described 12 new species and a southern WG endemic clade of SA Cnemaspis.Ten of the newly described species are endemic to the forests of the southern WG.We also identified 10 well-supported subclades that can be separated across morphological,geographic,and phylogenetic axes.A time-calibrated phylogeny and ancestral area reconstructions confirmed the Paleocene origin of SA Cnemaspis in the WG and provide insights into its evolutionary history and biogeography.The discovery of multiple endemic and deeply divergent lineages further highlights the evolutionary significance of the WG for lizards.
基金supported by the National Natural Science Foundation of China,No.31871211 (to YJunW)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。
文摘The low intrinsic growth capacity of neurons and an injury-induced inhibitory milieu are major contributo rs to the failure of sensory and motor functional recovery following spinal cord injury.Heat shock transcription factor 1(HSF1),a master regulator of the heat shock response,plays neurogenetic and neuroprotective roles in the damaged or diseased central nervous system.However,the underlying mechanism has not been fully elucidated.In the present study,we used a gecko model of spontaneous nerve regeneration to investigate the potential roles of gecko HSF1(gHSF1) in the regulation of neurite outgrowth and inflammatory inhibition of macrophages following spinal cord injury.gHSF1 expression in neurons and microglia at the lesion site increased dramatically immediately after tail amputation.gHSF1 ove rexpression in gecko primary neuro ns significantly promoted axonal growth by suppressing the expression of suppressor of cytokine signaling-3,and fa cilitated neuro nal survival via activation of the mitogen-activated extracellular signal-regulated kinase/extracellular regulated protein kinases and phosphatidylinositol 3-kinase/protein kinase B pathways.Furthermore,gHSF1 efficiently inhibited the macrophagemediated inflammatory response by inactivating 1kappa B-alpha/NF-kappaB signaling.Our findings show that HSF1 plays dual roles in promoting axonal regrowth and inhibiting leukocyte inflammation,and provide new avenues of investigation for promoting spinal co rd injury repair in mammals.
基金Financial support was provided by the National Natural Science Foundation of China(NSFC)(Grant No.31672269,31000949 to J.YAN)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJA330001 to P.LI)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP,PPZY2015B117)。
文摘Reptiles are the most morphologically and physiologically diverse tetrapods,with the squamates having the most diverse habitats.Lizard is an important model system for understanding the role of visual ecology,phylogeny and behavior on the structure of visual systems.In this study,we compared three opsin genes(RH2,LWS and SWS1)among 49 reptile species to detect positively selected genes as well as amino acid sites.Our results indicated that visual opsin genes have undergone divergent selection pressures in all lizards and RH2 and LWS suffered stronger positive selection than SWS1.Twelve positively selected sites were picked out for RH2 and LWS.Moreover,many diagnostic sites were found between geckos and non-gecko lizards,most of which were located near the positively selected sites and some of them have already been reported to be responsible for significant shifts of the wavelength of maximum absorption(λ_(max)).The results indicated that the gecko lineage accelerated the evolution of these genes to adapt to the dim-light environment or nocturnality as well as the switch between nocturnality and diurnality.
基金supported by the National Key R&D program of China (2019YFB1309600)National Natural Science Foundation of China (51975283).
文摘Geckos can move quickly in various environments by efficiently controlling their complex adhesive toe pads.The locomotion behaviours observed in the attachment-detachment(A-D)cycle of their toe pads in response to changes in their environment should be studied to understand the adaptive behavioural characteristics of such toe pads.The lack of systematic research on the entire A-D cycle,including the release,swing,contact,and adhesion stages,limits the comprehension of the adhesive locomotion mechanism.The A-D cycle of Gekko gecko that facilitates the foot locomotion on inclined and vertical surfaces was investigated to clarify the locomotion behaviours in different stages.Results show that the change trends of foot locomotor angles(yaw and pitch)during the entire A-D cycle remain unchanged in response to various substrates.The bending angles(fore 41°;hind 51°)and contact time percentages(fore 7.42%;hind 7.44%)in the contact stage as well as the forefoot angle ranges(yaw:163.09°;pitch:308.68°)in the A-D cycle also remain constant across all substrates.These invariant foot locomotion behaviours during the swing and contact stages suggest that the foot behaviours are weakly related to the forces acting on the foot,which change according to the environment.Furthermore,the forefoot and hindfoot have different anatomical structure and functional demands,thus,the angle range of forefoot locomotion is larger than that of hindfoot locomotion,and the pitch angle change trend of the forefoot is opposite to that of the hindfoot.The diverse and complex locomotion control of the adhesive toe pads for various environments is reduced by the consistent behaviours in the gecko’s A-D cycle,such as the constant postures in the swing and contact stages.This study provides insight into the adhesive locomotion mechanism of geckos and can facilitate further research on the effective design and control of adhesion robots.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.51435008,51705247,and 31601870)a Jiangsu Educational Innovation Program(Grant No.KYLX16_0327).
文摘Adhesion achieved through feet setae is fundamental for gecko agilely maneuvering.Although diverse hypotheses have been proposed,none of them thoroughly explains the setae function,implying a kind of hybrid-mechanism-based adhesion in geckos.In addition to van der Waals interactions and capillary force,the electrostatic attraction that emerges from triboelectrification was suggested as a component of setae adhesion.Nevertheless,the contribution by electrostatic attraction to the total setae attachment is still controversial.In this study,we analyzed the occurrence of electrostatic attraction at gecko setae through experiments and model analyses.By touching the substrates with only~1/70th of the foot area,freely wall-climbing geckos developed tribocharge at their feet setae with a density of~277 pC/mm^(2),generating electrostatic attractions with a strength of~4.4 mN/mm^(2).From this perspective,the adhesion driven by triboelectrification could account for about 1%of total adhesion.Model analyses at spatula level indicated a similar result showing that the electrostatic force might account for~3%of the adhesion that facilitates wall-climbing in geckos.The low contribution of the electrostatic force partly explains why geckos always face difficulty in maneuvering onto those substrates(e.g.,teflon)where they could easily develop tribocharge but difficultly generate van der Waals force.However,long-range electrostatic forces may play other roles in a distance range where the van der Waals interaction cannot function.These findings not only add to our understanding of the mechanism of gecko adhesion,but also will help us advance gecko-inspired fibular adhesives.
基金supported by the National Key Research&Development Program of China(Grant No.2020YFB1313504)the State Key Laboratory of Mechanics and Control for Aerospace Structures of Nanjing University of Aeronautics and Astronautics.
文摘Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.
基金supported by Jiangsu Special Project for Frontier Leading Base Technology(Grant Nos.BK20192004)Fundamental Research Funds for Central Universities(Grant Nos.B240201190)+3 种基金Changzhou Social Development Science and Technology Support Project(Grant Nos.CE20225037)Changzhou Science and Technology Project(Grant Nos.CM20223014)Suzhou Key Industrial Technology Innovation Forward-Looking Application Research Project(Grant Nos.SYG202143)Changzhou Science and Technology Project(Grant Nos.CJ20241061).
文摘Soft actuators are inherently flexible and compliant,traits that enhance their adaptability to diverse environments and tasks.However,their low structural stiffness can lead to unpredictable and uncontrollable complex deformations when substantial force is required,compromising their load-bearing capacity.This work proposes a novel method that uses gecko setae-inspired adhesives as interlayer films to construct a layer jamming structure to adjust the stiffness of soft actuators.The mechanical behavior of a single tilted microcylinder was analyzed using the energy method to determine the adhesion force of the adhesives.The gecko-inspired adhesive was designed under the guidance of the adhesion force model.Testing under various loads and directions revealed that the tilted characteristic of microcylinders can enhance the adhesion force in its grasping direction.The adhesive demonstrated excellent adhesion performance compared to other typical adhesives.A tunable stiffness actuator using gecko setae-inspired adhesives(TSAGA),was developed with these adhesives serving as interlayer films.The stiffness model of TSAGA was derived by analyzing its axial compression force.The results of stiffness test indicate that the adhesives serve as interlayer films can adjust the stiffness in response to applied load.TSAGA was compared with other typical soft actuators in order to evaluate the stiffness performance,and the results indicate that TSAGA exhibits the highest stiffness and the widest tunable stiffness range.This demonstrates the superior performance of the setae-inspired adhesives as interlayer films in terms of stiffness adjustment.
基金supported by Hainan Wanning Dazhou Island Marine Ecosystem National Natural Reserve Project: Survey of Terrestrial Animal Resources。
文摘A new species of gekkonid,Gekko liui sp.nov.,is described based on six specimens from Dazhou Island,Wanning City,Hainan,China.This new species is distinguished from its congeners by significant genetic divergence(>4.6% in the mitochondrial ND2 gene) and morphological characters,including a small body size(SVL 48.92– 56.67 mm,n = 6),nares in contact with rostral scale,37–42 interorbital scales between anterior corners of the eyes,140–148 ventral scales from mental to cloacal slit,103–118 midbody scale rows,34– 39 ventral scale rows,10–11 subdigital lamellae on the first toe and 12–13 on the fourth toe,webbing present in the fingers and toes,with tubercles on the dorsal surface of the tail,20–23 precloacal pores in males,and dorsal surface of body with six or seven large dark and brown bicolor bands between the nape and sacrum.The discovery of this new species brings the number of Gekko(subgenus Japonigekko) species in China to 23 and in Hainan Province to 4.
基金funded by The National Key R&D Program of China(2023YFC2205600)Open Project of Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.,Ltd.(YY-F805202312005)+1 种基金HIT Youth Scientist Laboratory Project,Postdoctoral Fellowship Program of CPSF(GZB20230259)the China Postdoctoral Science Foundation(2023TQ0133)(2023M731288).
文摘The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.
文摘Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein-coding, 2 ribosomal and 22 transfer RNA genes. The mt genome of Gekko is similar to most of the vertebrates in gene components, order, orientation, tRNA structures, low percentage of guanine and high percentage of thymine, and skews of base GC and AT. Base A was preferred at third codon positions for protein genes is similar to amphibians and fishes rather than amnion vertebrates. The standard stop codes (TAA) present only in three protein genes, less than those of most vertebrates. Transfer RNA genes range in length from 63 to 76 nt, their planar structure present characteristic clover leaf, except for tRNA-Cys and tRNA-Ser (AGY) because of lacking the D arm.
基金supported by the National Natural Science Foundation of China (U1602265,Mapping Karst Biodiversity in Yunnan)Strategic Priority Research Program of the Chinese Academy of Sciences (CAS)(XDA20050202)+2 种基金High-End Foreign Experts Program of Yunnan Province (Y9YN021B01,Yunnan Bioacoustic Monitoring Program)CAS 135 Program (2017XTBG-T03)Chinese Academy of Sciences Southeast Asia Biodiversity Research Center Fund (Y4ZK111B01)。
文摘Karst habitats are hotspots of diversity and endemism. Their naturally fragmented distributions across broad geographic landscapes have led to the complex array of smaller evolutionary ecosystems that present unique challenges from a conservation perspective.Comprehensivebiodiversity assessments of karst habitats have revealed that these ecosystems contain an almost unparalleled level of endemism, and many site-restricted species remain undescribed, thus posing considerable challenges for effective conservation management.Small rock-dwelling species, such as geckos, may be particularly prone to such isolation. In this paper, we discuss one such genus, i.e.,Hemiphyllodactylus, and explore its diversity across karst landforms in Yunnan Province, southwestern China. Based on morphological and genetic data, we describe two new species of Hemiphyllodactylus from karst habitats in Simao District and Yanshan County. A phylogenetic tree for Hemiphyllodactylus was constructed using 1?039 base pairs(bp) of the mitochondrial NADH dehydrogenase subunit 2 gene(ND2). The Simao and Yanshan specimens can be distinguished from all other congeners within their respective subclades based on uncorrected genetic pairwise distances greater than 6.3% and 4.3%respectively, as well as significant morphological differences. The discovery and description of these two new species brings the total number of described Hemiphyllodactylus species in China to 14and indicates many more undescribed species from unsurveyed karst regions await discovery.Our findings suggest that karst ecosystems in Yunnan support a higher diversity of Hemiphyllodactylus than previously known.This study also highlights the importance of karst ecosystems as refugia for sitespecific endemic species and the need for heightened conservation efforts.
文摘Polyacrylamide gel electrophoreses for malate dehydrogenase (Mdh) and beta-esterase (β-Est) isoenzymes were conducted for biochemical differentiation between two Stenodactylus gekkonid species inhabiting North Sinai of Egypt. Total lipids and proteins of liver and muscle tissues in both species were also analyzed. A total of three Mdh isoforms were recorded in the analysis, in which the activity of Mdh-2 and Mdh-3 seemed to be higher in S. petrii than in S. sthenodactylus. This high activity could be supported by the significant increase in the total lipids and proteins in liver and muscle tissues of the species. It may thus be reasonable to suppose that S. petrii is more active, energetic and adaptable in the desert habitat than S. sthenodactylus. β-Est showed six fractions in S. petrii and only one fraction in S. sthenodactylus. It is therefore noticeable that β-Est is more highly expressed in S. petrii than in S. sthenodactylus.
