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
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
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
A gecko's habitat possesses a wide range of climbing slopes that pose a number of postural challenges for climbing lo- comotion. Few studies have examined the relationship between the lateral bending of the trunk of ...A gecko's habitat possesses a wide range of climbing slopes that pose a number of postural challenges for climbing lo- comotion. Few studies have examined the relationship between the lateral bending of the trunk of a gecko and other aspects of locomotion when climbing. In this paper, three-dimensional reaction forces and high-speed videos of Gekko geckos moving on different slopes are used to reveal how the lateral bending of the animal's trunk responds to changing slopes. The results of such observations indicate that the minimum bending radius continually decreases with an increase in the slope, illustrating that the degree of bending of the trunk becomes significantly greater. Moreover, a lateral bending mechanical model is used to show the interrelation between the lateral bending in the frontal plane and the sagittal deformation of the trunk caused by gravity. Taken together, these results have advanced our understanding of the role of lateral bending of vertebrates when climbing on a slope.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
Since the commencement of climbing robots,the moving ability of climbing robots has continuously lagged far behind that of climbing animal.A primary cause is the insufficient understanding of how animals govern their ...Since the commencement of climbing robots,the moving ability of climbing robots has continuously lagged far behind that of climbing animal.A primary cause is the insufficient understanding of how animals govern their climbing locomotion.To reveal the mechanism of vertical locomotion and enhance the performance of climbing robots,we have measured the reaction forces acting on climbing geckos and recorded the locomotor behaviors synchronously.The coordinates of reference points were regressed to analyze kinematic feature factors.Meanwhile,the data of reaction forces were further processed by fast Fourier transform and wavelet transform to acquire time-frequency domain characteristics.The results show a good agreement between the reaction forces and the locomotor behaviors in time-frequency domain;the main locomotor frequency of trunk in fore-aft direction is twice that in lateral direction;the excellent adhesion system of geckos enables them to climbing up vertical substrate with not onIy a very tiny impact in time scale but also not easily identifiable characteristics in frequency-domain.Above research will help deepen our understanding of the climbing locomotion,and provide a more precise prototype for the design of gecko-like robot.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
The excellent climbing performance of the gecko is inspiring engineers and researchers for the design of artificial systems aimed at moving on vertical surfaces. Climbing robots could perform many useful tasks such as...The excellent climbing performance of the gecko is inspiring engineers and researchers for the design of artificial systems aimed at moving on vertical surfaces. Climbing robots could perform many useful tasks such as surveillance, inspection, repair, cleaning, and exploration. This paper presents and discusses the design, fabrication, and evaluation of two climbing robots which mimic the gait of the gecko. The first robot is designed considering macro-scale operations on Earth and in space. The second robot, whose motion is controlled using shape memory alloy actuators, is designed to be easily scaled down for micro-scale applications. Proposed bionic systems can climb up 65 degree slopes at a speed of 20 mm·s^-1.展开更多
Climbing robots are of potential use for surveillance, inspection and exploration in different environments. In particular, the use of climbing robots for space exploration can allow scientists to explore environments...Climbing robots are of potential use for surveillance, inspection and exploration in different environments. In particular, the use of climbing robots for space exploration can allow scientists to explore environments too challenging for traditional wheeled designs. To adhere to surfaces, biomimetic dry adhesives based on gecko feet have been proposed. These biomimetic dry adhesives work by using multi-scale compliant mechanisms to make intimate contact with different surfaces and adhere by using Van der Waals forces. Fabrication of these adhesives has frequently been challenging however, due to the difficulty in combining macro, micro and nanoscale compliance. We present an all polymer foot design for use with a hexapod climbing robot and a fabrication method to improve reliability and yield. A high strength, low-modulus silicone, TC-5005, is used to form the foot base and microscale fibres in one piece by using a two part mold. A macroscale foot design is produced using a 3D printer to produce a base mold, while lithographic definition of microscale fibres in a thick photoresist forms the 'hairs' of the polymer foot. The adhesion of the silicone fibres by themselves or attached to the macro foot is examined to determine best strategies for placement and removal of feet to maximize adhesion. Results demonstrate the successful integration of micro and macro compliant feet for use in climbing on a variety of surfaces.展开更多
This paper presents a kinematic analysis of the locomotion of a gecko,and experimental verification of the kinematic model.Kinematic analysis is important for parameter design,dynamic analysis,and optimization in biom...This paper presents a kinematic analysis of the locomotion of a gecko,and experimental verification of the kinematic model.Kinematic analysis is important for parameter design,dynamic analysis,and optimization in biomimetic robot research. The proposed kinematic analysis can simulate,without iteration,the locomotion of gecko satisfying the constraint conditions that maintain the position of the contacted feet on the surface.So the method has an advantage for analyzing the climbing motion of the quadruped mechanism in a real time application.The kinematic model of a gecko consists of four legs based on 7-degrees of freedom spherical-revolute-spherical joints and two revolute joints in the waist.The motion of the kinematic model is simulated based on measurement data of each joint.The motion of the kinematic model simulates the investigated real gecko's motion by using the experimental results.The analysis solves the forward kinematics by considering the model as a combination of closed and open serial mechanisms under the condition that maintains the contact positions of the attached feet on the ground. The motions of each joint are validated by comparing with the experimental results.In addition to the measured gait,three other gaits are simulated based on the kinematic model.The maximum strides of each gait are calculated by workspace analysis.The result can be used in biomimetic robot design and motion planning.展开更多
A new species of gekkonid,Hemiphyllodactylus dupanglingensis sp.nov.,is described based on six specimens from Hunan Province,China.The new species is phylogenetically close to H.zugi,H.hongkongensis,H.dushanensis,and ...A new species of gekkonid,Hemiphyllodactylus dupanglingensis sp.nov.,is described based on six specimens from Hunan Province,China.The new species is phylogenetically close to H.zugi,H.hongkongensis,H.dushanensis,and H.huishuiensis,and can be distinguished from its congeners by the following combination of cha racters:9-11 chin scales;postmental scales enlarged;9-12 infralabials,11-14 supralabials;14-16 dorsal scales and 10-11 ventral scales longitudinally arranged at the midbody contained with one eye diameter;a manual lamellar formula of 4-4-5-4 or 4-5-5-4 and a pedal lamellar formula of 4-5-5-5 or 5-6-6-4;21-25 continuous precloacal and femoral pores in males.展开更多
OBJECTIVE To explore the role of gecko crude peptides(GCPs)in the proliferation,apoptosis,migration and lymphangiogenesis of human hepatocellular carcinoma cells(Hep G2)and human lymphaticendothelial cells(HLECs)in vi...OBJECTIVE To explore the role of gecko crude peptides(GCPs)in the proliferation,apoptosis,migration and lymphangiogenesis of human hepatocellular carcinoma cells(Hep G2)and human lymphaticendothelial cells(HLECs)in vitro.METHODS The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay was used to evaluate the anti-proliferative effect of GCPs and si RNA-VEGF-C on Hep G2 cells,Hoechst 33258 staining and flow cytometry were performed to analyze cycle and apoptosis.The migration and invasion ability of cells were assayed by transwell chamber experiment and wound-healing assay.The protein and m RNA expressions of vascular endothelial growth factor-C(VEGF-C)and CXC chemokine receptor-4(CXCR4)were detected by q-PCR,immunofluorescence,Western blot.The protein expressions of the extracellular signal regulated kinase(ERKI/2),c-Jun N-terminal kinase(JNK),p38-mitogen activated protein kinases(p38 MAPK),serine/threonine kinase(Akt)and phosphatidylinositol-3-kinase(PI3K)were detected by western blot.The anti-lymphangiogenesis effect of GCPs on the HLECs was analyzed using an in vitro tube-formation assay.The protein and m RNA expressions of vascular endothelial growth factor receptor-3(VEGFR-3)and stromal cell-derived factor-1(SDF-1)were detected by q-PCR,Western blot.RESULTS GCPs and si RNA-VEGF-C inhibited Hep G2 proliferation,invasion and migration,and the most obvious inhibitory effect was both synergistic effects.Thus,GCPs suppressed HLECs proliferation,migration and tubelike structure formationin a dose-dependent manner,and had inhibitory effect of tumor-induced lymphangiogenesis in vitro.Additionally,we found that GCPs and si RNA-VEGF-C decreased the expressions of MMP-2,MMP-9,VEGF-C,CXCR4,phospho-ERK1/2,phospho-P38,phospho-JNK and PI3K in Hep G2 cells.Moreover,GCPs had a dose-dependent depressive effecton the expressions of VEGFR-3,SDF-1 in HLECs.CONCLUSION The low expression of VEGF-C mediated by si RNA-VEGF-C and GCPs inhibit tumor proliferation,invasion and migrationby suppressing the MAPK signaling pathway through reduced levels of VEGF-C,and GCPs inhibit tumor lymphangiogenesis by suppressing the CXCR4/SDF-1 signaling pathway through suppressed VEGF-C/VEGFR-3.展开更多
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 work was supported by the National Natural Science Foundation of China (Grant No. 61175105 and 51435008), the Doctoral Fund of Ministry of Education of China (Grant No. 20123218110031) and the Funda- mental Research Funds for the Central Universities (Grant No. CXZZI 1_0198 and BCXJ10 10).
文摘A gecko's habitat possesses a wide range of climbing slopes that pose a number of postural challenges for climbing lo- comotion. Few studies have examined the relationship between the lateral bending of the trunk of a gecko and other aspects of locomotion when climbing. In this paper, three-dimensional reaction forces and high-speed videos of Gekko geckos moving on different slopes are used to reveal how the lateral bending of the animal's trunk responds to changing slopes. The results of such observations indicate that the minimum bending radius continually decreases with an increase in the slope, illustrating that the degree of bending of the trunk becomes significantly greater. Moreover, a lateral bending mechanical model is used to show the interrelation between the lateral bending in the frontal plane and the sagittal deformation of the trunk caused by gravity. Taken together, these results have advanced our understanding of the role of lateral bending of vertebrates when climbing on a slope.
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the National Natural Science Foundation of China(Grant Nos.31601870 and 51435008)the Natural Science Foundation of Jiangsu Province,China(Grant No.SBK20160800).
文摘Since the commencement of climbing robots,the moving ability of climbing robots has continuously lagged far behind that of climbing animal.A primary cause is the insufficient understanding of how animals govern their climbing locomotion.To reveal the mechanism of vertical locomotion and enhance the performance of climbing robots,we have measured the reaction forces acting on climbing geckos and recorded the locomotor behaviors synchronously.The coordinates of reference points were regressed to analyze kinematic feature factors.Meanwhile,the data of reaction forces were further processed by fast Fourier transform and wavelet transform to acquire time-frequency domain characteristics.The results show a good agreement between the reaction forces and the locomotor behaviors in time-frequency domain;the main locomotor frequency of trunk in fore-aft direction is twice that in lateral direction;the excellent adhesion system of geckos enables them to climbing up vertical substrate with not onIy a very tiny impact in time scale but also not easily identifiable characteristics in frequency-domain.Above research will help deepen our understanding of the climbing locomotion,and provide a more precise prototype for the design of gecko-like robot.
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.
文摘The excellent climbing performance of the gecko is inspiring engineers and researchers for the design of artificial systems aimed at moving on vertical surfaces. Climbing robots could perform many useful tasks such as surveillance, inspection, repair, cleaning, and exploration. This paper presents and discusses the design, fabrication, and evaluation of two climbing robots which mimic the gait of the gecko. The first robot is designed considering macro-scale operations on Earth and in space. The second robot, whose motion is controlled using shape memory alloy actuators, is designed to be easily scaled down for micro-scale applications. Proposed bionic systems can climb up 65 degree slopes at a speed of 20 mm·s^-1.
文摘Climbing robots are of potential use for surveillance, inspection and exploration in different environments. In particular, the use of climbing robots for space exploration can allow scientists to explore environments too challenging for traditional wheeled designs. To adhere to surfaces, biomimetic dry adhesives based on gecko feet have been proposed. These biomimetic dry adhesives work by using multi-scale compliant mechanisms to make intimate contact with different surfaces and adhere by using Van der Waals forces. Fabrication of these adhesives has frequently been challenging however, due to the difficulty in combining macro, micro and nanoscale compliance. We present an all polymer foot design for use with a hexapod climbing robot and a fabrication method to improve reliability and yield. A high strength, low-modulus silicone, TC-5005, is used to form the foot base and microscale fibres in one piece by using a two part mold. A macroscale foot design is produced using a 3D printer to produce a base mold, while lithographic definition of microscale fibres in a thick photoresist forms the 'hairs' of the polymer foot. The adhesion of the silicone fibres by themselves or attached to the macro foot is examined to determine best strategies for placement and removal of feet to maximize adhesion. Results demonstrate the successful integration of micro and macro compliant feet for use in climbing on a variety of surfaces.
基金supported by the Brain Korea 21 Project and SNU-IAMD.
文摘This paper presents a kinematic analysis of the locomotion of a gecko,and experimental verification of the kinematic model.Kinematic analysis is important for parameter design,dynamic analysis,and optimization in biomimetic robot research. The proposed kinematic analysis can simulate,without iteration,the locomotion of gecko satisfying the constraint conditions that maintain the position of the contacted feet on the surface.So the method has an advantage for analyzing the climbing motion of the quadruped mechanism in a real time application.The kinematic model of a gecko consists of four legs based on 7-degrees of freedom spherical-revolute-spherical joints and two revolute joints in the waist.The motion of the kinematic model is simulated based on measurement data of each joint.The motion of the kinematic model simulates the investigated real gecko's motion by using the experimental results.The analysis solves the forward kinematics by considering the model as a combination of closed and open serial mechanisms under the condition that maintains the contact positions of the attached feet on the ground. The motions of each joint are validated by comparing with the experimental results.In addition to the measured gait,three other gaits are simulated based on the kinematic model.The maximum strides of each gait are calculated by workspace analysis.The result can be used in biomimetic robot design and motion planning.
基金supported by the National Natural Science Foundation of China(Grant No.31472021)the Project for Endangered Wildlife Investigation,Supervision and Industry Regulation of the National Forestry and Grassland Bureau of China(No.2019072-HN-001)。
文摘A new species of gekkonid,Hemiphyllodactylus dupanglingensis sp.nov.,is described based on six specimens from Hunan Province,China.The new species is phylogenetically close to H.zugi,H.hongkongensis,H.dushanensis,and H.huishuiensis,and can be distinguished from its congeners by the following combination of cha racters:9-11 chin scales;postmental scales enlarged;9-12 infralabials,11-14 supralabials;14-16 dorsal scales and 10-11 ventral scales longitudinally arranged at the midbody contained with one eye diameter;a manual lamellar formula of 4-4-5-4 or 4-5-5-4 and a pedal lamellar formula of 4-5-5-5 or 5-6-6-4;21-25 continuous precloacal and femoral pores in males.
基金supported by Medical Science and Technology Research Project of Henan Province(142102310031)
文摘OBJECTIVE To explore the role of gecko crude peptides(GCPs)in the proliferation,apoptosis,migration and lymphangiogenesis of human hepatocellular carcinoma cells(Hep G2)and human lymphaticendothelial cells(HLECs)in vitro.METHODS The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay was used to evaluate the anti-proliferative effect of GCPs and si RNA-VEGF-C on Hep G2 cells,Hoechst 33258 staining and flow cytometry were performed to analyze cycle and apoptosis.The migration and invasion ability of cells were assayed by transwell chamber experiment and wound-healing assay.The protein and m RNA expressions of vascular endothelial growth factor-C(VEGF-C)and CXC chemokine receptor-4(CXCR4)were detected by q-PCR,immunofluorescence,Western blot.The protein expressions of the extracellular signal regulated kinase(ERKI/2),c-Jun N-terminal kinase(JNK),p38-mitogen activated protein kinases(p38 MAPK),serine/threonine kinase(Akt)and phosphatidylinositol-3-kinase(PI3K)were detected by western blot.The anti-lymphangiogenesis effect of GCPs on the HLECs was analyzed using an in vitro tube-formation assay.The protein and m RNA expressions of vascular endothelial growth factor receptor-3(VEGFR-3)and stromal cell-derived factor-1(SDF-1)were detected by q-PCR,Western blot.RESULTS GCPs and si RNA-VEGF-C inhibited Hep G2 proliferation,invasion and migration,and the most obvious inhibitory effect was both synergistic effects.Thus,GCPs suppressed HLECs proliferation,migration and tubelike structure formationin a dose-dependent manner,and had inhibitory effect of tumor-induced lymphangiogenesis in vitro.Additionally,we found that GCPs and si RNA-VEGF-C decreased the expressions of MMP-2,MMP-9,VEGF-C,CXCR4,phospho-ERK1/2,phospho-P38,phospho-JNK and PI3K in Hep G2 cells.Moreover,GCPs had a dose-dependent depressive effecton the expressions of VEGFR-3,SDF-1 in HLECs.CONCLUSION The low expression of VEGF-C mediated by si RNA-VEGF-C and GCPs inhibit tumor proliferation,invasion and migrationby suppressing the MAPK signaling pathway through reduced levels of VEGF-C,and GCPs inhibit tumor lymphangiogenesis by suppressing the CXCR4/SDF-1 signaling pathway through suppressed VEGF-C/VEGFR-3.