Autotomy of appendages is a self-protection mechanism in crustaceans,which is defined as the reflexive loss of a limb in response to predation,competition,or other environmental factors.Single-limb injuries were the m...Autotomy of appendages is a self-protection mechanism in crustaceans,which is defined as the reflexive loss of a limb in response to predation,competition,or other environmental factors.Single-limb injuries were the most common among the species surveyed in the present study,and the chelicerae were the most frequently lost appendages.After autotomy,hormones and signaling pathways are altered.Loss of limbs can affect foraging efficiency,although cheliped loss may be compensated by shifting to alternative prey or using both motor and oral appendages.In heterogeneous species,the loss of the major chelae may affect the selectivity of feeding.Autotomy can affect crustacean growth by reducing size increases at molting and altering the timing of ecdysis.In commercial production,removing chelicerae is an effective strategy to reduce cannibalism,and production of soft-shell crabs can be increased via autotomy.After autotomy,a new limb will regrow through regeneration and molting.This process involves the regulation of hormones,regrowth of nerves,and a number of signaling pathways that include the Wnt/β-catenin signaling pathway and transforming growth factorβsignaling pathway.Crustaceans are somewhat different from vertebrates in terms of regeneration.This review provides theoretical guidance about autotomy and regeneration applied in artificial aquaculture,and we offer several suggestions for future research on autotomy and regeneration in crustaceans.展开更多
Tail autotomy is a defense mechanism used by many lizards to evade predators, but it entails costs. We used the oriental leaf-toed gecko Hemidactylus bowringii as a model animal to evaluate locomotor costs of tail aut...Tail autotomy is a defense mechanism used by many lizards to evade predators, but it entails costs. We used the oriental leaf-toed gecko Hemidactylus bowringii as a model animal to evaluate locomotor costs of tail autotomy. We removed the tail about 5 mm from the tail base from each of the experimental geckos(adult males) initially having intact tails. Tailless experimental geckos and tailed control geckos were measured for overall speed and sprint speed in both vertical and horizontal directions. Overall speed and sprint speed did not differ between tailless and tailed geckos. The influence of locomotor direction on both overall speed and sprint speed was significant, with horizontal speed being greater than vertical speed. The interaction between tail condition and locomotor direction was not significant in overall speed, but was significant in sprint speed. Tailless geckos had faster vertical sprint speed than the tailed individuals. Of the 130 field-caught adults, 59 had previously lost their tails, with most(about 61%) of them shedding their tails near the tail base. Neither the proportion of geckos with tail autotomy nor the frequency distribution of locations of the tail break differed between the sexes. Our data show that tail loss of H. bowringii occurs frequently in nature. However, tail loss does not incur locomotor costs in this gecko.展开更多
Autotomy has evolved independently several times in different animal lineages.It frequently involves immediate functional costs,so regeneration evolved in many instances to restore the functionality of that body part....Autotomy has evolved independently several times in different animal lineages.It frequently involves immediate functional costs,so regeneration evolved in many instances to restore the functionality of that body part.Caudal autotomy is a widespread antipredator strategy in lizards,although it may affect energy storage,locomotion dynamics,or survival in future encounters with predators.Here,we assessed the effect of tail loss on the locomotor performance of wall lizards(Podarcis muralis),as well as the recovery of locomotor functionality of lizards with regenerated tails,and the movement dynamics of shed tails that were either intact or having regenerated portions.Tail loss had no effect on locomotion over unhindered spaces,possibly due to compensation between a negative effect on the stride of front limbs,and a positive effect of losing mass and friction force.We found a clear negative impact of tail loss on locomotion in spaces with interspersed obstacles,in which tailed lizards jumped larger distances when leaving the obstacles.Besides,lizards that used the tail to push off the ground were able to approach the obstacles from further,so that the tail seemed to be useful when used during jumping.Regeneration fully restores lizard’s locomotor capacities,but tail antipredator value,as indicated by the intensity of post-autotomic movements,is only partially retrieved.From these results,we propose that,together with the recovery of post-autotomy antipredator capacities,the restoration of the organismal locomotor performance may have been an important,yet frequently neglected factor in the evolution of lizard’s regeneration ability.展开更多
We used the Chinese skink Eumeces chinensis as a model animal to study the effects of tail loss on reproductive in- vestment and offspring traits. A total of 147 wild-captured adult females were divided into four grou...We used the Chinese skink Eumeces chinensis as a model animal to study the effects of tail loss on reproductive in- vestment and offspring traits. A total of 147 wild-captured adult females were divided into four groups according to their tail con- ditions. Tail breaks occurred most frequently in the proximal portion of the tail and least frequently in the distal portion, with the middle portion in between. This finding suggests that tail breaks occurring in nature often entails substantial energetic costs in E. chinensis where the tail is a major site of energy storage. The proportion of females that laid eggs was higher in females with in- tact or completely regenerated tails than in those with broken tails. Following whole-tail autotomy, the clutch size was reduced by 17%, and the clutch mass was reduced by 14%. Females undergoing substantial tail autotomy reduced reproductive investment, and they did so by reducing the number but not the size of eggs produced. None of the egg and hatchling traits was affected by tail loss. Comparing our data with those reported for other oviparous and viviparous skinks allows us to draw two general conclu- sions： one is that fecundity （clutch or litter size） is affected by tail loss in all species so far studied, whereas offspring size is af- fected by tail loss in some species, but not in others; the other is that the reduction in fecundity following tail loss is more evident in species lacking abdominal fat bodies展开更多
Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve injury.However,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly understood.In thi...Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve injury.However,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly understood.In this study,local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in rats.After 8 weeks of combined treatment,the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection,the mRNA expression of nerve growth factor,a pain marker,in the proximal nerve stump was decreased,the density of regenerated axons was decreased,the thickness of the myelin sheath was increased,and the ratio of unmyelinated to myelinated axons was reduced.Moereover,the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were decreased.The combined treatment exhibited superior effects in these measures to chitin conduit treatment alone.These findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic pain.This study was approved by the Animal Ethics Committee of Peking University People’s Hospital(approval No.2019PHE027)on December 5,2019.展开更多
Many lizard species use caudal autotomy to escape entrapment. Conspicuous coloration may increase the likelihood of being attacked, but if that attack can be directed towards the autotomous tail this may ultimately in...Many lizard species use caudal autotomy to escape entrapment. Conspicuous coloration may increase the likelihood of being attacked, but if that attack can be directed towards the autotomous tail this may ultimately increase the chances of the lizard surviving a predatory attack. We tested the hypothesis that brightly-colored tails function to divert predatory attention away from the head and body using pairs of blue-tailed and all-brown clay model lizards. Predatory bird attacks on the 24 blue-tailed models occurred sooner （P = 0.001） than attacks on the 24 all-brown models, and over 7 days blue-tailed models were attacked more often than all-brown models （P = 0.007）. Blue-tailed models were, however, more frequently attacked on the tail than other parts of the body （P 〈 0.001）, while all-brown models were more frequently attacked on the head and body （P = 0.019） which would be more likely to be fatal for a real lizard. Our results suggest that models with a blue tail were more conspicuous than all-brown models, attracting attacks sooner and more often, but that the attacks were predominantly directed at the tail. It is better for individuals to be attacked unsuccessfully many times, than successfully just once. Having a brightly-colored tail may, therefore, act as a ＇risky decoy＇. Despite increased conspicuousness, a blue tail increases the likelihood that the lizard would be able to effect escape through caudal autotomy rather than being grabbed by the head or body [Current Zoology 60 （3）： 333-337, 2014].展开更多
Neuroma formation after peripheral nerve transection often leads to severe neuropathic pain.Regenerative peripheral nerve interface has been shown to reduce painful neuroma in the clinic.However,no reports have invest...Neuroma formation after peripheral nerve transection often leads to severe neuropathic pain.Regenerative peripheral nerve interface has been shown to reduce painful neuroma in the clinic.However,no reports have investigated the underlying mechanisms,and no comparative animal studies on regenerative peripheral nerve interface and other means of neuroma prevention have been conducted to date.In this study,we established a rat model of left sciatic nerve transfection,and subsequently interfered with the model using the regenerative peripheral nerve interface or proximal nerve stump implantation inside a fully innervated muscle.Results showed that,compared with rats subjected to nerve stump implantation inside the muscle,rats subjected to regenerative peripheral nerve interface intervention showed greater inhibition of the proliferation of collagenous fibers and irregular regenerated axons,lower expressions of the fibrosis markerα-smooth muscle actin and the inflammatory marker sigma-1 receptor in the proximal nerve stump,lower autophagy behaviors,lower expressions of c-fos and substance P,higher expression of glial cell line-derived neurotrophic factor in the ipsilateral dorsal root ganglia.These findings suggested that regenerative peripheral nerve interface inhibits peripheral nerve injury-induced neuroma formation and neuropathic pain possibly via the upregulation of the expression of glial cell line-derived neurotrophic factor in the dorsal root ganglia and reducing neuroinflammation in the nerve stump.展开更多
基金funded by the National Natural Science Foundation of China(Nos.32172993,42106104)the Ningbo Provincial Natural Science Foundation of China(No.202003N4181).
文摘Autotomy of appendages is a self-protection mechanism in crustaceans,which is defined as the reflexive loss of a limb in response to predation,competition,or other environmental factors.Single-limb injuries were the most common among the species surveyed in the present study,and the chelicerae were the most frequently lost appendages.After autotomy,hormones and signaling pathways are altered.Loss of limbs can affect foraging efficiency,although cheliped loss may be compensated by shifting to alternative prey or using both motor and oral appendages.In heterogeneous species,the loss of the major chelae may affect the selectivity of feeding.Autotomy can affect crustacean growth by reducing size increases at molting and altering the timing of ecdysis.In commercial production,removing chelicerae is an effective strategy to reduce cannibalism,and production of soft-shell crabs can be increased via autotomy.After autotomy,a new limb will regrow through regeneration and molting.This process involves the regulation of hormones,regrowth of nerves,and a number of signaling pathways that include the Wnt/β-catenin signaling pathway and transforming growth factorβsignaling pathway.Crustaceans are somewhat different from vertebrates in terms of regeneration.This review provides theoretical guidance about autotomy and regeneration applied in artificial aquaculture,and we offer several suggestions for future research on autotomy and regeneration in crustaceans.
基金supported by grants from Innovative Team Project of Nanjing Normal University(Project No.0319PM0902)Priority Academic Program Development of Jiangsu Higher Education Institutions(CXLX11_0885)to Xiang JI
文摘Tail autotomy is a defense mechanism used by many lizards to evade predators, but it entails costs. We used the oriental leaf-toed gecko Hemidactylus bowringii as a model animal to evaluate locomotor costs of tail autotomy. We removed the tail about 5 mm from the tail base from each of the experimental geckos(adult males) initially having intact tails. Tailless experimental geckos and tailed control geckos were measured for overall speed and sprint speed in both vertical and horizontal directions. Overall speed and sprint speed did not differ between tailless and tailed geckos. The influence of locomotor direction on both overall speed and sprint speed was significant, with horizontal speed being greater than vertical speed. The interaction between tail condition and locomotor direction was not significant in overall speed, but was significant in sprint speed. Tailless geckos had faster vertical sprint speed than the tailed individuals. Of the 130 field-caught adults, 59 had previously lost their tails, with most(about 61%) of them shedding their tails near the tail base. Neither the proportion of geckos with tail autotomy nor the frequency distribution of locations of the tail break differed between the sexes. Our data show that tail loss of H. bowringii occurs frequently in nature. However, tail loss does not incur locomotor costs in this gecko.
基金the Ministry of Infrastructures,Land Use and Environment of the Principality of Asturias Regional Government,for the capture and maintenance of the animals(2017/007429)The authors thank Tania Rodríguez Díaz for her helpful comments on the language.Irene Fernández-Rodríguez was supported by a Severo Ochoa fellowship from the Principality of Asturias(BP16192).
文摘Autotomy has evolved independently several times in different animal lineages.It frequently involves immediate functional costs,so regeneration evolved in many instances to restore the functionality of that body part.Caudal autotomy is a widespread antipredator strategy in lizards,although it may affect energy storage,locomotion dynamics,or survival in future encounters with predators.Here,we assessed the effect of tail loss on the locomotor performance of wall lizards(Podarcis muralis),as well as the recovery of locomotor functionality of lizards with regenerated tails,and the movement dynamics of shed tails that were either intact or having regenerated portions.Tail loss had no effect on locomotion over unhindered spaces,possibly due to compensation between a negative effect on the stride of front limbs,and a positive effect of losing mass and friction force.We found a clear negative impact of tail loss on locomotion in spaces with interspersed obstacles,in which tailed lizards jumped larger distances when leaving the obstacles.Besides,lizards that used the tail to push off the ground were able to approach the obstacles from further,so that the tail seemed to be useful when used during jumping.Regeneration fully restores lizard’s locomotor capacities,but tail antipredator value,as indicated by the intensity of post-autotomic movements,is only partially retrieved.From these results,we propose that,together with the recovery of post-autotomy antipredator capacities,the restoration of the organismal locomotor performance may have been an important,yet frequently neglected factor in the evolution of lizard’s regeneration ability.
基金Acknowledgments This study was supported by grants from the National Science Foundation of China （Project No. 30670281） and the Zhejiang Provincial Department of Education （Project No. Y200908723）. We thank Lai-Gao Luo, Long-Hui Lin, Yan-Fu Qu, Xi-Dong Zhang, Hong Li and Hong-Xia Liu for their help during the research.
文摘We used the Chinese skink Eumeces chinensis as a model animal to study the effects of tail loss on reproductive in- vestment and offspring traits. A total of 147 wild-captured adult females were divided into four groups according to their tail con- ditions. Tail breaks occurred most frequently in the proximal portion of the tail and least frequently in the distal portion, with the middle portion in between. This finding suggests that tail breaks occurring in nature often entails substantial energetic costs in E. chinensis where the tail is a major site of energy storage. The proportion of females that laid eggs was higher in females with in- tact or completely regenerated tails than in those with broken tails. Following whole-tail autotomy, the clutch size was reduced by 17%, and the clutch mass was reduced by 14%. Females undergoing substantial tail autotomy reduced reproductive investment, and they did so by reducing the number but not the size of eggs produced. None of the egg and hatchling traits was affected by tail loss. Comparing our data with those reported for other oviparous and viviparous skinks allows us to draw two general conclu- sions： one is that fecundity （clutch or litter size） is affected by tail loss in all species so far studied, whereas offspring size is af- fected by tail loss in some species, but not in others; the other is that the reduction in fecundity following tail loss is more evident in species lacking abdominal fat bodies
基金the National Natural Science Foundation of China,No.31771322Major R&D Program of National Ministry of Science and Technology of China,No.2018YFB1105504+1 种基金Beijing Natural Science Foundation of China,No.7212121and Shenzhen Science and Technology Plan Project of China,No.JCYJ20190806162205278(all to PXZ).
文摘Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve injury.However,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly understood.In this study,local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in rats.After 8 weeks of combined treatment,the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection,the mRNA expression of nerve growth factor,a pain marker,in the proximal nerve stump was decreased,the density of regenerated axons was decreased,the thickness of the myelin sheath was increased,and the ratio of unmyelinated to myelinated axons was reduced.Moereover,the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were decreased.The combined treatment exhibited superior effects in these measures to chitin conduit treatment alone.These findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic pain.This study was approved by the Animal Ethics Committee of Peking University People’s Hospital(approval No.2019PHE027)on December 5,2019.
文摘Many lizard species use caudal autotomy to escape entrapment. Conspicuous coloration may increase the likelihood of being attacked, but if that attack can be directed towards the autotomous tail this may ultimately increase the chances of the lizard surviving a predatory attack. We tested the hypothesis that brightly-colored tails function to divert predatory attention away from the head and body using pairs of blue-tailed and all-brown clay model lizards. Predatory bird attacks on the 24 blue-tailed models occurred sooner （P = 0.001） than attacks on the 24 all-brown models, and over 7 days blue-tailed models were attacked more often than all-brown models （P = 0.007）. Blue-tailed models were, however, more frequently attacked on the tail than other parts of the body （P 〈 0.001）, while all-brown models were more frequently attacked on the head and body （P = 0.019） which would be more likely to be fatal for a real lizard. Our results suggest that models with a blue tail were more conspicuous than all-brown models, attracting attacks sooner and more often, but that the attacks were predominantly directed at the tail. It is better for individuals to be attacked unsuccessfully many times, than successfully just once. Having a brightly-colored tail may, therefore, act as a ＇risky decoy＇. Despite increased conspicuousness, a blue tail increases the likelihood that the lizard would be able to effect escape through caudal autotomy rather than being grabbed by the head or body [Current Zoology 60 （3）： 333-337, 2014].
基金supported by the Health Commission of Hubei Province Medical Leading Talent Project,No.LJ20200405(to AXY)。
文摘Neuroma formation after peripheral nerve transection often leads to severe neuropathic pain.Regenerative peripheral nerve interface has been shown to reduce painful neuroma in the clinic.However,no reports have investigated the underlying mechanisms,and no comparative animal studies on regenerative peripheral nerve interface and other means of neuroma prevention have been conducted to date.In this study,we established a rat model of left sciatic nerve transfection,and subsequently interfered with the model using the regenerative peripheral nerve interface or proximal nerve stump implantation inside a fully innervated muscle.Results showed that,compared with rats subjected to nerve stump implantation inside the muscle,rats subjected to regenerative peripheral nerve interface intervention showed greater inhibition of the proliferation of collagenous fibers and irregular regenerated axons,lower expressions of the fibrosis markerα-smooth muscle actin and the inflammatory marker sigma-1 receptor in the proximal nerve stump,lower autophagy behaviors,lower expressions of c-fos and substance P,higher expression of glial cell line-derived neurotrophic factor in the ipsilateral dorsal root ganglia.These findings suggested that regenerative peripheral nerve interface inhibits peripheral nerve injury-induced neuroma formation and neuropathic pain possibly via the upregulation of the expression of glial cell line-derived neurotrophic factor in the dorsal root ganglia and reducing neuroinflammation in the nerve stump.
