Deep-sea mussels of the subfamily Bathymodiolinae are common and numerically dominant species widely distributed in cold seeps and hydrothermal vents.During long-time evolution,deep-sea mussels have evolved to be well...Deep-sea mussels of the subfamily Bathymodiolinae are common and numerically dominant species widely distributed in cold seeps and hydrothermal vents.During long-time evolution,deep-sea mussels have evolved to be well adapted to the local environment of cold seeps and hydrothermal vents by various ways,especially by establishing endosymbiosis with chemotrophic bacteria.However,biological processes underlying the establishment and maintenance of symbiosis between host mussels and symbionts are largely unclear.In the present study,Gigantidas platifrons genes possibly involved in the symbiosis with methane oxidation symbionts were identified and characterized by Lipopolysaccharide(LPS)pull-down and in situ hybridization.Five immune related proteins including Toll-like receptor 2(TLR2),integrin,vacuolar sorting protein(VSP),matrix metalloproteinase 1(MMP1),and leucine-rich repeat(LRR-1)were identified by LPS pull-down assay.These five proteins were all conserved in either molecular sequences or functional domains and known to be key molecules in host immune recognition,phagocytosis,and lysosome-mediated digestion.Furthermore,in situ hybridization of LRR-1,TLR2 and VSP genes was conducted to investigate their expression patterns in gill tissues of G.platifrons.Consequently,LRR-1,TLR2,and VSP genes were found expressed exclusively in the bacteriocytes of G.platifrons.Therefore,it was suggested that TLR2,integrin,VSP,MMP1,and LRR-1 might be crucial molecules in the symbiosis between G.platifrons and methane oxidation bacteria by participating in symbiosis-related immune processes.展开更多
The digestive gland of the apple snail Pomacea canaliculata lodges two types of pigmented corpuscles(identified as C and K corpuscles)which has been proposed as endosymbiont/s.Both corpuscular types are always present...The digestive gland of the apple snail Pomacea canaliculata lodges two types of pigmented corpuscles(identified as C and K corpuscles)which has been proposed as endosymbiont/s.Both corpuscular types are always present in the digestive gland of adult snails,they are released into the tubuloacinar lumen and are later expelled in the feces.On their part,hatchlings lack any C or K corpuscles in the digestive gland as well as in their feces,whereas C corpuscles appear in both the gland and feces within one week after hatching.Hence,it is possible that the detritivorous hatchlings acquire the putative C-endosymbiont from feces in the sediments where they live,i.e.through‘lateral’or‘horizontal’transmission.This possibility was put to test in an experiment in which we prevented any lateral transmission,by a 7-days aseptic culture,with no food,of aseptically obtained hatchlings.At the end of the experiment,we observed that most juveniles had survived the culture period,and hence the digestive glands and feces of survivors were studied by light microscopy of resin embedded,toluidine blue-stained sections.All studied glands and fecal samples showed C corpuscles.It is concluded that lateral transmission of the endosymbiont,if any,is not indispensable for the acquisition of the endosymbiont by hatchlings.展开更多
Mutualisms are cooperative interactions between members of different species. We focus on obligate mutualism, where each species cannot survive without the other. From a theoretical aspect, obligate mutualism is simil...Mutualisms are cooperative interactions between members of different species. We focus on obligate mutualism, where each species cannot survive without the other. From a theoretical aspect, obligate mutualism is similar to the relationship between male and female. Empirical data indicate a sex-ratio selection: male and female have a specific ratio in their population sizes. In the present paper, we apply lattice model to obligate mutualism between two species, and present a theory of “ratio selection” which is a generalization of sex-ratio selection. Computer simulations are carried out by two methods: local and global interactions. In the former, interactions occur between neighbouring cells, while in the latter they occur between any pair of cells. Simulations in both interactions show the so-called Allee effect: both species can survive, when both densities are large in some extent. However, we find a large difference between local and global simulations. In the case of local interaction, restriction for survival is found to be extremely severe compared to global interaction. Both species require a proper ratio for their sustainability. This result leads to the theory of ratio selection: when interaction occurs locally, the ratio of both species is uniquely determined. We discuss that the ratio selection explains not only the evolution of endosymbionts from free-living ancestors but also the evolution from endosymbionts to organelles.展开更多
Microbial symbioses have had profound impacts on the evolution of animals.Conversely,changes in host biology may impact the evolutionary trajectory of symbionts themselves.Blattabacterium cuenoti is present in almost ...Microbial symbioses have had profound impacts on the evolution of animals.Conversely,changes in host biology may impact the evolutionary trajectory of symbionts themselves.Blattabacterium cuenoti is present in almost all cockroach species and enables hosts to subsist on a nutrient-poor diet.To investigate if host biology has impacted Blattabacterium at the genomic level,we sequenced and analyzed 25 genomes from Australian soil-burrowing cockroaches(Blaberidae:Panesthiinae),which have undergone at least seven separate subterranean,subsocial transitions from above-ground,wood-feeding ancestors.We find at least three independent instances of genome erosion have occurred in Blattabacterium strains exclusive to Australian soil-burrowing cockroaches.These shrinkages have involved the repeated inactivation of genes involved in amino acid biosynthesis and nitrogen recycling,the core role of Blattabacterium in the host-symbiont relationship.The most drastic of these erosions have occurred in hosts thought to have transitioned underground the earliest relative to other lineages,further suggestive of a link between gene loss in Blattabacterium and the burrowing behavior of hosts.As Blattabacterium is unable to fulfill its core function in certain host lineages,these findings suggest soil-burrowing cockroaches must acquire these nutrients from novel sources.Our study represents one of the first cases,to our knowledge,of parallel host adaptations leading to concomitant parallelism in their mutualistic symbionts,further underscoring the intimate relationship between these two partners.展开更多
The legume-rhizobium symbiosis represents the most important system for terrestrial biological nitrogen fixation on land.Efficient nitrogen fixation during this symbiosis depends on successful rhizobial infection and ...The legume-rhizobium symbiosis represents the most important system for terrestrial biological nitrogen fixation on land.Efficient nitrogen fixation during this symbiosis depends on successful rhizobial infection and complete endosymbiosis,which are achieved by complex cellular events including cell-wall remodeling,cytoskeletal reorganizations,and extensive membrane expansion and trafficking.In this review,we explore the dynamic remodeling of the plant-specific cell wall-membrane system-cytoskeleton(WMC)continuum during symbiotic nitrogen fixation.We focus on key processes linked to efficient nitrogen fixation,including rhizobial uptake,infection thread formation and elongation,rhizobial droplet release,cytoplasmic bridge formation,and rhizobial endosymbiosis.Additionally,we discuss the advanced techniques for investigating the cellular basis of root-nodule symbiosis and provide insights into the unsolved mysteries of robust symbiotic nitrogen fixation.展开更多
Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioen...Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for chan- nels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple stra- tegies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.展开更多
The stability of cnidarian-dinoflagellate endosymbioses is dependent upon communication between the host gastrodermal cell and the symbionts housed within it. Although the molecular mechanisms remain to be elucidated,...The stability of cnidarian-dinoflagellate endosymbioses is dependent upon communication between the host gastrodermal cell and the symbionts housed within it. Although the molecular mechanisms remain to be elucidated, existing evidence suggests that the establishment of these endosymbioses may involve the sorting of membrane proteins. The present study examined the role of host gastrodermal membranes in regulating symbiont （genus Symbiodinium） photosynthesis in the stony coral Euphyllia glabrescens. In comparison with the photosynthetic behavior of Symbiodinium in culture, the Symbiodinium populations within isolated symbiotic gastrodermal cells （SGCs） exhibited a significant degree of photo-inhibition, as determined by a decrease in the photochemical efficiency of photosystem II （Fv/Fm）. This photo-inhibition coincided with increases in plasma membrane perturbation and oxidative activity in the SGCs. Membrane trafficking in SGCs was examined using the metabolism of a fluo- rescent lipid analog, N-[5-（5,7-dimethyl boron dipyrromethene difluoride）-l-pentanoyl]-D-erythro-Sphingosylpbosphoryl- choline （BODIPY-Sphingomyelin or BODIPY-SM）. Light irradiation altered both membrane distribution and trafficking of BODIPY-SM, resulting in metabolic changes. Cholesterol depletion of the SGC plasma membranes by methyl-13-cyclodextrin retarded BODIPY-SM degradation and further augmented Symbiodinium photo-inhibition. These results indicate that Symbio- dinium photo-inhibition may be related to perturbation of the host gastrodermal membrane, providing evidence for the pivotal role of host membrane trafficking in the regulation of this environmentally important coral-dinoflagellate endosymbiosis.展开更多
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22050303)the Key Research Program of Frontier Sciences,CAS(No.ZDBS-LY-DQC032)+2 种基金the National Key Research and Development Program of China(No.2018YFC0310800)the National Natural Science Foundation of China(No.41906103)the Taishan Scholars Project to SUN Song。
文摘Deep-sea mussels of the subfamily Bathymodiolinae are common and numerically dominant species widely distributed in cold seeps and hydrothermal vents.During long-time evolution,deep-sea mussels have evolved to be well adapted to the local environment of cold seeps and hydrothermal vents by various ways,especially by establishing endosymbiosis with chemotrophic bacteria.However,biological processes underlying the establishment and maintenance of symbiosis between host mussels and symbionts are largely unclear.In the present study,Gigantidas platifrons genes possibly involved in the symbiosis with methane oxidation symbionts were identified and characterized by Lipopolysaccharide(LPS)pull-down and in situ hybridization.Five immune related proteins including Toll-like receptor 2(TLR2),integrin,vacuolar sorting protein(VSP),matrix metalloproteinase 1(MMP1),and leucine-rich repeat(LRR-1)were identified by LPS pull-down assay.These five proteins were all conserved in either molecular sequences or functional domains and known to be key molecules in host immune recognition,phagocytosis,and lysosome-mediated digestion.Furthermore,in situ hybridization of LRR-1,TLR2 and VSP genes was conducted to investigate their expression patterns in gill tissues of G.platifrons.Consequently,LRR-1,TLR2,and VSP genes were found expressed exclusively in the bacteriocytes of G.platifrons.Therefore,it was suggested that TLR2,integrin,VSP,MMP1,and LRR-1 might be crucial molecules in the symbiosis between G.platifrons and methane oxidation bacteria by participating in symbiosis-related immune processes.
文摘The digestive gland of the apple snail Pomacea canaliculata lodges two types of pigmented corpuscles(identified as C and K corpuscles)which has been proposed as endosymbiont/s.Both corpuscular types are always present in the digestive gland of adult snails,they are released into the tubuloacinar lumen and are later expelled in the feces.On their part,hatchlings lack any C or K corpuscles in the digestive gland as well as in their feces,whereas C corpuscles appear in both the gland and feces within one week after hatching.Hence,it is possible that the detritivorous hatchlings acquire the putative C-endosymbiont from feces in the sediments where they live,i.e.through‘lateral’or‘horizontal’transmission.This possibility was put to test in an experiment in which we prevented any lateral transmission,by a 7-days aseptic culture,with no food,of aseptically obtained hatchlings.At the end of the experiment,we observed that most juveniles had survived the culture period,and hence the digestive glands and feces of survivors were studied by light microscopy of resin embedded,toluidine blue-stained sections.All studied glands and fecal samples showed C corpuscles.It is concluded that lateral transmission of the endosymbiont,if any,is not indispensable for the acquisition of the endosymbiont by hatchlings.
文摘Mutualisms are cooperative interactions between members of different species. We focus on obligate mutualism, where each species cannot survive without the other. From a theoretical aspect, obligate mutualism is similar to the relationship between male and female. Empirical data indicate a sex-ratio selection: male and female have a specific ratio in their population sizes. In the present paper, we apply lattice model to obligate mutualism between two species, and present a theory of “ratio selection” which is a generalization of sex-ratio selection. Computer simulations are carried out by two methods: local and global interactions. In the former, interactions occur between neighbouring cells, while in the latter they occur between any pair of cells. Simulations in both interactions show the so-called Allee effect: both species can survive, when both densities are large in some extent. However, we find a large difference between local and global simulations. In the case of local interaction, restriction for survival is found to be extremely severe compared to global interaction. Both species require a proper ratio for their sustainability. This result leads to the theory of ratio selection: when interaction occurs locally, the ratio of both species is uniquely determined. We discuss that the ratio selection explains not only the evolution of endosymbionts from free-living ancestors but also the evolution from endosymbionts to organelles.
基金supported by the Australian Research Council(grant no.FT160100463)。
文摘Microbial symbioses have had profound impacts on the evolution of animals.Conversely,changes in host biology may impact the evolutionary trajectory of symbionts themselves.Blattabacterium cuenoti is present in almost all cockroach species and enables hosts to subsist on a nutrient-poor diet.To investigate if host biology has impacted Blattabacterium at the genomic level,we sequenced and analyzed 25 genomes from Australian soil-burrowing cockroaches(Blaberidae:Panesthiinae),which have undergone at least seven separate subterranean,subsocial transitions from above-ground,wood-feeding ancestors.We find at least three independent instances of genome erosion have occurred in Blattabacterium strains exclusive to Australian soil-burrowing cockroaches.These shrinkages have involved the repeated inactivation of genes involved in amino acid biosynthesis and nitrogen recycling,the core role of Blattabacterium in the host-symbiont relationship.The most drastic of these erosions have occurred in hosts thought to have transitioned underground the earliest relative to other lineages,further suggestive of a link between gene loss in Blattabacterium and the burrowing behavior of hosts.As Blattabacterium is unable to fulfill its core function in certain host lineages,these findings suggest soil-burrowing cockroaches must acquire these nutrients from novel sources.Our study represents one of the first cases,to our knowledge,of parallel host adaptations leading to concomitant parallelism in their mutualistic symbionts,further underscoring the intimate relationship between these two partners.
基金National Natural Science Foundation of China for Z.K.(grant nos.31925003,32230007,32241045)and X.Z.(grant no.32000142).
文摘The legume-rhizobium symbiosis represents the most important system for terrestrial biological nitrogen fixation on land.Efficient nitrogen fixation during this symbiosis depends on successful rhizobial infection and complete endosymbiosis,which are achieved by complex cellular events including cell-wall remodeling,cytoskeletal reorganizations,and extensive membrane expansion and trafficking.In this review,we explore the dynamic remodeling of the plant-specific cell wall-membrane system-cytoskeleton(WMC)continuum during symbiotic nitrogen fixation.We focus on key processes linked to efficient nitrogen fixation,including rhizobial uptake,infection thread formation and elongation,rhizobial droplet release,cytoplasmic bridge formation,and rhizobial endosymbiosis.Additionally,we discuss the advanced techniques for investigating the cellular basis of root-nodule symbiosis and provide insights into the unsolved mysteries of robust symbiotic nitrogen fixation.
文摘Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for chan- nels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple stra- tegies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.
基金The present study is dedicated to the memory of our mentor Professor Richard E.Pagano (1944 2010)supported by the National Science Council of Taiwan (Grant No.NSC 98-2311-B-291-001-MY3).
文摘The stability of cnidarian-dinoflagellate endosymbioses is dependent upon communication between the host gastrodermal cell and the symbionts housed within it. Although the molecular mechanisms remain to be elucidated, existing evidence suggests that the establishment of these endosymbioses may involve the sorting of membrane proteins. The present study examined the role of host gastrodermal membranes in regulating symbiont （genus Symbiodinium） photosynthesis in the stony coral Euphyllia glabrescens. In comparison with the photosynthetic behavior of Symbiodinium in culture, the Symbiodinium populations within isolated symbiotic gastrodermal cells （SGCs） exhibited a significant degree of photo-inhibition, as determined by a decrease in the photochemical efficiency of photosystem II （Fv/Fm）. This photo-inhibition coincided with increases in plasma membrane perturbation and oxidative activity in the SGCs. Membrane trafficking in SGCs was examined using the metabolism of a fluo- rescent lipid analog, N-[5-（5,7-dimethyl boron dipyrromethene difluoride）-l-pentanoyl]-D-erythro-Sphingosylpbosphoryl- choline （BODIPY-Sphingomyelin or BODIPY-SM）. Light irradiation altered both membrane distribution and trafficking of BODIPY-SM, resulting in metabolic changes. Cholesterol depletion of the SGC plasma membranes by methyl-13-cyclodextrin retarded BODIPY-SM degradation and further augmented Symbiodinium photo-inhibition. These results indicate that Symbio- dinium photo-inhibition may be related to perturbation of the host gastrodermal membrane, providing evidence for the pivotal role of host membrane trafficking in the regulation of this environmentally important coral-dinoflagellate endosymbiosis.
