Tachypleus tridentatus,a critical biological resource used in Limulus Amebocyte Lysate(LAL),has experienced a sharp decline that is attracting global attention.Although artificial husbandry and breeding are promising ...Tachypleus tridentatus,a critical biological resource used in Limulus Amebocyte Lysate(LAL),has experienced a sharp decline that is attracting global attention.Although artificial husbandry and breeding are promising strategies for promoting the proliferation of T.tridentatus,technological research is still in its infancy.Studying the behavioral characteristics during the reproductive period is crucial for identifying the environmental requirements of T.tridentatus.In this study,the behaviors of adult T.tridentatus were recorded continuously in an artificial aquaculture environment using underwater cameras.The behavior of adult T.tridentatus is mainly characterized by locomotion,feeding,and reproduction,which encompass a total of 11 types of behavior.The types of locomotion,including respiratory,swimming,climbing,and turning over,were coordinated with each other.Particularly,specific swimming patterns were utilized to efficiently conserve energy.Tachypleus tridentatus effectively utilized coordinated movements of its appendages to assist in feeding.This multi-organ coordinated feeding strategy allowed them to move quickly or avoid threats,thereby preventing food from being taken by others.The coordinated feeding pattern involving multiple organs enhances efficiency during rapid movement or evasion,protecting the food from being contested by other organisms.Competitive courtship and a monogamous mating strategy allowed T.tridentatus to efficiently find mates and lay eggs in suitable environments.Repeated spawning behaviors contributed to the high reproductive success rate.This study elucidated the ecological requirements of T.tridentatus from a behavioral perspective,thereby providing valuable references for implementing and optimizing its rearing environment.展开更多
Effective culture and management of adult tri-spine horseshoe crab,Tachypleus tridentatus can ensure that stock enhancement programs and aquaculture systems are maintained.To explore suitable feed for animals during t...Effective culture and management of adult tri-spine horseshoe crab,Tachypleus tridentatus can ensure that stock enhancement programs and aquaculture systems are maintained.To explore suitable feed for animals during the breeding season,Pacific oyster(Ostrea gigas)(oyster group;OG)and frozen sharpbelly fish(Hemiculter leucisculus)(frozen fish group;FG)were selected to feed 20 T.tridentatus male and female pairs,respectively.At the end of the experiment,intestinal samples were obtained to measure digestive enzymes activities.The intestinal flora were determined by 16S r DNA sequencing.No eggs were observed in the FG and one T.tridentatus adult died.No animals died in the OG,and 9.7×10;eggs were obtained.These results show that oysters are more suitable for the development and reproduction of adult T.tridentatus than frozen fish.Additionally,the digestive enzyme activity analysis revealed that animals in the OG exhibited higher protein digestibility than those in the FG,but no significant differences in lipid and carbohydrate uptake were observed between the groups.Furthermore,the intestinal flora analysis showed that operational taxonomic units(OTUs)and the Chao1 index were significantly higher in the OG than in the FG,but no significant difference was observed in the Shannon or Simpson indices between the groups.Our data indicate that the oyster diet improved the intestinal microbial diversity of T.tridentatus.We hypothesize that nutrients,such as oyster-based taurine,proteins,and highly unsaturated fatty acids,improve protease activity in the T.tridentatus digestive tract,alter the intestinal floral structure,and improve the reproductive performance of T.tridentatus.展开更多
Gonadotropin-releasing hormone （GnRH） is a crucial peptide for the regulation of reproduction. Using immunological techniques, we investigated the presence of GnRH in horseshoe crab Tachypleus tridentatus. Octopus G...Gonadotropin-releasing hormone （GnRH） is a crucial peptide for the regulation of reproduction. Using immunological techniques, we investigated the presence of GnRH in horseshoe crab Tachypleus tridentatus. Octopus GnRH-like immunoreactivity, tunicate GnRH-like immunoreactivity, and lamprey GnRH-I-like immunoreactivity were detected in the neurons and fibers of the protocerebrum. However, no mammal GnRH-like immunoreactivity or lamprey GnRH-LII-like immunoreactivity was observed. Our results suggest that a GnRH-like factor, an ancient peptide, existed in the brain of T. tridentatus and may be involved in the reproductive endocrine system.展开更多
Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg s...Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg survival rates per day were highest in the mid intertidal zone(45.1%±25.4%)and the lowest in the low intertidal zone(13.3%±27.6%).Differences in the elevation,air exposure time,and water content of the spawning ground were significant factors determining the egg survival rates.Excessive or insufficient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival.On the other hand,moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone.This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning.Therefore,the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development.By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches,a positive contribution can be made to future management and conservation.The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.展开更多
The population of tri-spine horseshoe crabs(HSCs)Tachypleus tridentatus has sharply decreased in recent decades.Domestication and manual releasing are now used to recover it.In order to accelerate the growth of T.trid...The population of tri-spine horseshoe crabs(HSCs)Tachypleus tridentatus has sharply decreased in recent decades.Domestication and manual releasing are now used to recover it.In order to accelerate the growth of T.tridentatus in indoor environment,in this study,gut microbiota of 2nd instar T.tridentatus was supposed to be improved by putting probiotics in water environment and thus promoted the health and growth of the host.Using 16S rRNA sequencing of gut samples,we examined the intestinal microbiome of juvenile HSCs and studied the effect of probiotics.Results showed that there was no significant difference between groups fed with high and low concentrations(1×10^(7),1×10^(12)CFU mL^(−1))of Bacillus subtilis and high concentration(1×10^(12)CFU mL^(−1))of Lactobacillus,and no significant difference compared with the control group,but the diversity of Lactobacillus group with low concentration(1×10^(7)CFU mL^(−1))was significantly higher than those of other groups.Microbial-mediated functions predicted by PICRUSt showed that‘Cellular Processes’,‘Metabolism’and‘Organismal Systems’pathways significantly increased in groups of Bacillus subtilis and Lactobacillus group with low concentration.The results showed that two types of probiotics with different concentrations have other effects on the structure,richness and function of intestinal microbes.By searching the literature and conducting pre-experiments,we forecasted the short time of breeding under the probiotic environment may not have much effect.The present study for the first time investigated the impact of probiotics on gut microbiota of juvenile HSCs and found them may benefit for the growth and health of HSCs.展开更多
Knowledge of dietary compositions is essential to the recovery of the dwindling populations of horseshoe crabs in China.The feeding habits of Tachypleus tridentatus and Carcinoscorpis rotundicauda of Pearl Bay in sout...Knowledge of dietary compositions is essential to the recovery of the dwindling populations of horseshoe crabs in China.The feeding habits of Tachypleus tridentatus and Carcinoscorpis rotundicauda of Pearl Bay in southwestern China were studied by stable isotope analysis.Hemolymph samples of the two species were obtained from two age groups living in different habitats(inner,central,and outer Bay).In addition,their potential food source samples were collected in May 2019.Results showed that the mean values ofδ^(13)C andδ^(15)N in C.rotundicauda individuals ranged from−19.01‰to−16.47‰and from 10.49‰to 13.5‰,respectively,and those of T.tridentatus ranged from−19.12‰to−14.96‰and from 8.78‰to 13.48‰,respectively.These values indicated that the horseshoe crabs have a wide variety of food sources and therefore are highly omnivorous.No remarkably correlations were found betweenδ^(13)C andδ^(15)N values and individual widths in the two species.Thirteen potential food sources were selected,in which Sipunculus nudus,Batillaria zonalisi,and Ulva lactuca contributed largely to the dietary compositions of the two species of horseshoe crabs.No significant correlation was found between the feeding habits and habitat geochemical characteristics of the horseshoe crabs.All these results possibly indicate the high diversity of their food sources and the indiscriminate dietary compositions of the two Asian horseshoe crabs.展开更多
The AFLP(amplified fragment length polymorphism) technique was used to analyze and compare the genetic diversity of Tachypleus tridentatus from three south-eastern coastal sites of China(Pingtan,Hong Kong and Beihai)....The AFLP(amplified fragment length polymorphism) technique was used to analyze and compare the genetic diversity of Tachypleus tridentatus from three south-eastern coastal sites of China(Pingtan,Hong Kong and Beihai).Eight pairs of primers generated 361 loci,including 285 polymorphic loci.The ratio of polymorphic loci was 96.97%.Nei's genetic diversity index was 0.420 8 and the Shannon information index was 0.607 5,both of which were higher than that reported for many other arthropods.These results show that the genetic diversity detected was mainly caused by individual differences within a population.Genetic distance showed that the rational division of the three geographic populations of T.tridentatus along the south-eastern coast of China was not significant,in which the genetic distance was not proportional to the geographic distance.All three horseshoe crab populations may belong to a large group,and had a high degree of genetic similarity.The high level of genetic diversity obtained from the present AFLP analysis may be due to the large effective population size of the species in Chinese waters.展开更多
Transcriptome assemblies for the stomach,midgut,and fecal mucosa of Tachypleus tridentatus and Carcinoscorpius rotundicauda are reported for the first time in this study.Genome assembly resulted in 373069 unigenes wit...Transcriptome assemblies for the stomach,midgut,and fecal mucosa of Tachypleus tridentatus and Carcinoscorpius rotundicauda are reported for the first time in this study.Genome assembly resulted in 373069 unigenes with an N50 of 1314,while transcriptome assembly resulted in 736378 unigenes and an N50 of 2121.The annotated unigenes showed the highest similarity to fishes,amphibians,and reptiles,with most unigenes closely related to metabolism,translation,biogenesis,signal transduction,energy production,immune response,and secretion.Unigenes(4768)were mapped to KEGG pathways,and the most enriched pathways were involved in translation,environmental information signal processing,metabolism,endocrine system,immune system,nervous system,and varying metabolism.Totally 65889,2001,and 7162 differentially expressed genes(DEGs)were identified in the stomach,midgut,and fecal mucosa between the two horseshoe crab species,respectively.Compared with C.rotundicauda,99.95%of the DEGs in the T.tridentatus stomach were down-regulated,while 99.97%of the DEGs of T.tridentatus fecal mucosa and 55.42%of the DEGs of the T.tridentatus midgut were up-regulated.Most midgut DEGs were involved in hydrolase activity,protein metabolism,and cell cytoplasm,while most stomach and fecal mucosa DEGs were involved in catalytic activity and primary metabolic processes.Most stomach DEGs were assigned to the cellular component in cellular macromolecular complexes,while most fecal mucosa DEGs were assigned to the cellular component in cell and cell parts.These results will benefit the investigation of the molecular mechanisms of the digestive tract related to the feeding habits and environmental traces of horseshoe crabs.展开更多
Population genetic structure and historical demography of Chinese horseshoe crab (T.tridentatus)along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit Ⅰ (COI...Population genetic structure and historical demography of Chinese horseshoe crab (T.tridentatus)along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit Ⅰ (COI) fragment.The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province,Meizhou and Zhangpu in Fujian Province,Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province.Sequence variation was relatively low with a total of seven transitions observed.In all localities,Haplotype H3 was the dominant type observed among eight haplotypes defined previously,and was at the center of radiation in Median-Joining network.The prolonged star-like network suggests a signature of population expansions.The level of diversity was low in total,with haplotype diversity ( Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.00118,respectively.The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations.Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion.The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.展开更多
Horseshoe crabs,the most well-known example of“living fossils”,are iconic and ecologically important macroinvertebrates in coastal and estuarine ecosystems.Their blood is a crucial resource for manufacturing Limulus...Horseshoe crabs,the most well-known example of“living fossils”,are iconic and ecologically important macroinvertebrates in coastal and estuarine ecosystems.Their blood is a crucial resource for manufacturing Limulus or Tachypleus amebocyte lysate to detect bacterial endotoxins or fungal contamination in drug and medical devices.An enhanced understanding of their ecological roles and trophic interactions in the food webs is fundamental to facilitate resource management for the declining populations in Asia.Foraging information of the Asian species,however,is mainly derived from preliminary,scattered reports from a limited number of study locations.In this study,resource utilization,trophic niche dynamics,and trophic interaction of the juvenile tri-spine horseshoe crab,Tachypleus tridentatus(instars 1–12,approximately 0.5–8 years old)across ontogeny was assessed in diversified nursery habitats along the northern Beibu Gulf,China,using carbon and nitrogen stable isotopes.Our results suggest that:(i)T.tridentatus are ecological generalists given the vast range of carbon isotopic values and trophic niche width estimates exhibited between multiple instar groups;(ii)juvenile T.tridentatus across most habitat types predominantly assimilated energy from a variety of basal production sources in the food web,but primarily depended on sedimentary organic matter and seagrass resource pools;(iii)ontogenetic shifts in juvenile dietary proportions were evident,with decreased reliance on sedimentary organic matter,coupled with increased reliance on benthic macroinvertebrate grazers,detritivores,and omnivores with age;and(iv)nearly all juvenile instars occupied similar trophic positions in the food web with slight shifts in trophic position present with increasing size.Our findings indicate that resource availability and ontogenetic diet shifts strongly influence horseshoe crab trophic dynamics,and age should be accounted when formulating habitat conservation measures based on resource use for Asian horseshoe crabs.展开更多
Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals,including aquatic animals.As the haemolymph of horseshoe crabs(Tachypleus)conta...Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals,including aquatic animals.As the haemolymph of horseshoe crabs(Tachypleus)contains broad ranges of bioactive compounds,we have explored the in vivo immunostimulating potential of amoebocyte lysate and plasma using a fish model.Indian major carp,Labeo rohita,yearlings were injected intraperitoneally with two doses of lysate and plasma at 50 and 100µg protein per fish.No abnormalities and/or mortalities were recorded in any group.L.rohita injected with 50µg lysate and 100µg plasma protein showed significant enhancement(P<0.01)of various haematological and immunological parameters.There was a significant rise in the total protein and globulin content,myeloperoxidase and respiratory burst activity following injection with 50µg lysate and 100µg plasma protein.The agglutinating and haemagglutinating activities were increased albeit not significantly(P>0.01)in any groups.On the contrary,a significantly high hemolysin titre was recorded in fish that received 100µg plasma protein.Following challenge with Aeromonas hydrophila,both lysate and plasma protein(s)cross protected the fish after 30 days.The highest survival(50%)was recorded in group injected with 50µg lysate protein,followed by 45%in both 100µg lysate and plasma protein injected groups.展开更多
Identification,protection and restoration of spawning habitats are vital for protecting the depleted species.Asian horseshoe crabs are ecologically important macroinvertebrates in coastal and estuarine ecosystems.Howe...Identification,protection and restoration of spawning habitats are vital for protecting the depleted species.Asian horseshoe crabs are ecologically important macroinvertebrates in coastal and estuarine ecosystems.However,their spawning habitat studies were limited to several reports in tropical regions,possibly due to the lack of modified survey methods,particularly in habitats with a lower density of spawning adults,and/or intermingled with anthropogenic structures.In this study,the year-round egg distribution and spawning habitat baselines of Carcinoscorpius rotundicauda and Tachypleus tridentatus were determined in the northern Beibu Gulf,China.Our findings demonstrated that the peak spawning occurred in June–July and ceased in November–January when the average water temperature dropped below 20℃.Egg aggregations were found<10 cm beneath the sediment surface with regular tidal inundation,regardless of seasonal changes,in the vicinity of natural and artificial structures with elevated,mildly sloping substratum within the high tide zones.The nests were characterized by medium-sized sediment grains(0.5–0.9 mm),high temperatures(31–34℃),low water contents(0.8%–0.9%),and total organic carbon contents(0.5%–0.7%),which might maximize the hatching success.The identified nesting beaches were close to nursery habitats for juveniles,and tidal creeks were present as the possible corridor connecting these two important habitats through the dominant mangrove forests.The findings provide valuable insights in the scope of spawning behavior and nest-site selection of Asian horseshoe crabs under a mixture of natural and artificial structures,which could benefit future management efforts for the exploited spawning populations.展开更多
The anti-endotoxic effect of syringic acid (SA) isolated from Radix Isatidis (Banlangen, BLG) was studied. SA was extracted and isolated from BLG and diluted into 1 % solution. The content of SA-pretreated endotoxin (...The anti-endotoxic effect of syringic acid (SA) isolated from Radix Isatidis (Banlangen, BLG) was studied. SA was extracted and isolated from BLG and diluted into 1 % solution. The content of SA-pretreated endotoxin (ET) was quantitatively determined using Limulus test. The ability of fever induction of ET pretreated with SA was measured using endotoxin-induced fever test in rabbits. The LPS-induced death in mice pretreated with and without SA was compared. Results showed that after pretreatment with SA, 83. 16 % of ET was destroyed, the ET-induced fever in rabbits relieved markedly and the LPS-induced death rate in mice dropped from 68 % to 20 %. It was concluded that SA isolated from BLG had anti-endotoxic effects.展开更多
The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentration...The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentrations of bacterial endotoxin （1 EU/mL, 0.5 EU/mL and 0.25 EU/mL） were treated by LTP for different time （20 s, 40 s and 60 s）. Tachypleus amebocyte lysate （TAL） method was employed to detect the concentration variation of bacterial endotoxin before and af- ter the plasma treatment, and endotoxic shock mice model was used to evaluate the inactivation effects of LTP on endotoxin for further study. Experimental results demonstrated that, DBD plasma can inactivate the bacterial endotoxin quickly and effectively, and when the LTP treatment time was increased, the concentrations of bacterial endotoxin decreased gradually （after 60 s plasma treatment, its inactivation effect was beyond the Chinese pharmacopoeia standard）, and the average survival time of mice gradually extended. The possible inactivation mechanisms are proposed to be related to reactive oxygen species （ROSs）.展开更多
Bycatch poses a severe challenge to global fishery management.Although studies have focused on marine megafauna bycatch,research on relevant issues regarding invertebrates is limited,particularly for the threatened ho...Bycatch poses a severe challenge to global fishery management.Although studies have focused on marine megafauna bycatch,research on relevant issues regarding invertebrates is limited,particularly for the threatened horseshoe crabs.In this study,the distribution of fishing gears and the bycatch intensity of Asian horseshoe crabs in the intertidal zones of the northern Beibu Gulf that harbors the most abundant juvenile Asian horseshoe crabs populations in China were evaluated.Seven intertidal nursery habitats for Tachypleus tridentatus and Carcinoscorpius rotundicauda were surveyed from May to July in 2021.A transect that crossed the tidal creeks and tidal flats between the high tide embankment/vegetation and low tide line of a given habitat was surveyed during the ebb tides.The type,number,and GPS of fishing gears were recorded when sighted,and the number and prosomal width of each horseshoe crab species were measured.Bycatch intensities differed among habitats,ranging from 0.3 to 18.4 and 1.2 to 22.7 individuals per kilometer of transect for T.tridentatus and C.rotundicauda,respectively.Among the three identified fishing gear types,ground cages and stick net sets caused a stronger bycatch pressure on these two species.Most T.tridentatus bycatch and C.rotundicauda bycatch were large individuals in late juvenile and adult stages.Therefore,the ground cages and stick net sets along/near the tidal creeks,mangrove fringe,and low tide line should be regulated and removed to ensure the functionality of the intertidal zone as the spawning corridor and nursery habitat of Asian horseshoe crabs.展开更多
基金The National Key Research and Development Program under contract No.2024YFD2401404the Natural Science Foundation of Guangdong Province under contract No.2024A1515012696+2 种基金the Offshore Wind Power Joint Fund of Natural Science Foundation of Guangdong Province under contract No.2023A1515240004the Natural Science Foundation of Hainan Province under contract No.322MS154the Fund of Key Laboratory of South China Sea Fishery Resources Exploitation and Utilization,Ministry of Agriculture and Rural Affairs,P.R.China under contract No.FREU2023-07。
文摘Tachypleus tridentatus,a critical biological resource used in Limulus Amebocyte Lysate(LAL),has experienced a sharp decline that is attracting global attention.Although artificial husbandry and breeding are promising strategies for promoting the proliferation of T.tridentatus,technological research is still in its infancy.Studying the behavioral characteristics during the reproductive period is crucial for identifying the environmental requirements of T.tridentatus.In this study,the behaviors of adult T.tridentatus were recorded continuously in an artificial aquaculture environment using underwater cameras.The behavior of adult T.tridentatus is mainly characterized by locomotion,feeding,and reproduction,which encompass a total of 11 types of behavior.The types of locomotion,including respiratory,swimming,climbing,and turning over,were coordinated with each other.Particularly,specific swimming patterns were utilized to efficiently conserve energy.Tachypleus tridentatus effectively utilized coordinated movements of its appendages to assist in feeding.This multi-organ coordinated feeding strategy allowed them to move quickly or avoid threats,thereby preventing food from being taken by others.The coordinated feeding pattern involving multiple organs enhances efficiency during rapid movement or evasion,protecting the food from being contested by other organisms.Competitive courtship and a monogamous mating strategy allowed T.tridentatus to efficiently find mates and lay eggs in suitable environments.Repeated spawning behaviors contributed to the high reproductive success rate.This study elucidated the ecological requirements of T.tridentatus from a behavioral perspective,thereby providing valuable references for implementing and optimizing its rearing environment.
基金the fund of the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0605)the Guangdong Provincial Key Laboratory of Fishery Ecology and Environment(No.FEEL-2020-2)+2 种基金the Science and Technology Planning Project of Guangdong Province(No.2019B121201001)the Special Fund for Basic Scientific Research of Central Public Research Institutes of South China Sea Fisheries Research Institute,the Chinese Academy of Fishery(No.2019TS21)the National Natural Science Foundation of China(No.42067038)。
文摘Effective culture and management of adult tri-spine horseshoe crab,Tachypleus tridentatus can ensure that stock enhancement programs and aquaculture systems are maintained.To explore suitable feed for animals during the breeding season,Pacific oyster(Ostrea gigas)(oyster group;OG)and frozen sharpbelly fish(Hemiculter leucisculus)(frozen fish group;FG)were selected to feed 20 T.tridentatus male and female pairs,respectively.At the end of the experiment,intestinal samples were obtained to measure digestive enzymes activities.The intestinal flora were determined by 16S r DNA sequencing.No eggs were observed in the FG and one T.tridentatus adult died.No animals died in the OG,and 9.7×10;eggs were obtained.These results show that oysters are more suitable for the development and reproduction of adult T.tridentatus than frozen fish.Additionally,the digestive enzyme activity analysis revealed that animals in the OG exhibited higher protein digestibility than those in the FG,but no significant differences in lipid and carbohydrate uptake were observed between the groups.Furthermore,the intestinal flora analysis showed that operational taxonomic units(OTUs)and the Chao1 index were significantly higher in the OG than in the FG,but no significant difference was observed in the Shannon or Simpson indices between the groups.Our data indicate that the oyster diet improved the intestinal microbial diversity of T.tridentatus.We hypothesize that nutrients,such as oyster-based taurine,proteins,and highly unsaturated fatty acids,improve protease activity in the T.tridentatus digestive tract,alter the intestinal floral structure,and improve the reproductive performance of T.tridentatus.
基金Supported by the National Natural Science Foundation of China(No.41076081)
文摘Gonadotropin-releasing hormone （GnRH） is a crucial peptide for the regulation of reproduction. Using immunological techniques, we investigated the presence of GnRH in horseshoe crab Tachypleus tridentatus. Octopus GnRH-like immunoreactivity, tunicate GnRH-like immunoreactivity, and lamprey GnRH-I-like immunoreactivity were detected in the neurons and fibers of the protocerebrum. However, no mammal GnRH-like immunoreactivity or lamprey GnRH-LII-like immunoreactivity was observed. Our results suggest that a GnRH-like factor, an ancient peptide, existed in the brain of T. tridentatus and may be involved in the reproductive endocrine system.
文摘Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg survival rates per day were highest in the mid intertidal zone(45.1%±25.4%)and the lowest in the low intertidal zone(13.3%±27.6%).Differences in the elevation,air exposure time,and water content of the spawning ground were significant factors determining the egg survival rates.Excessive or insufficient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival.On the other hand,moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone.This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning.Therefore,the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development.By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches,a positive contribution can be made to future management and conservation.The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.
基金the National Natural Science Foundation of China(No.31872587)the CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediationthe YICCAS Grant(No.2020 KFJJ11)。
文摘The population of tri-spine horseshoe crabs(HSCs)Tachypleus tridentatus has sharply decreased in recent decades.Domestication and manual releasing are now used to recover it.In order to accelerate the growth of T.tridentatus in indoor environment,in this study,gut microbiota of 2nd instar T.tridentatus was supposed to be improved by putting probiotics in water environment and thus promoted the health and growth of the host.Using 16S rRNA sequencing of gut samples,we examined the intestinal microbiome of juvenile HSCs and studied the effect of probiotics.Results showed that there was no significant difference between groups fed with high and low concentrations(1×10^(7),1×10^(12)CFU mL^(−1))of Bacillus subtilis and high concentration(1×10^(12)CFU mL^(−1))of Lactobacillus,and no significant difference compared with the control group,but the diversity of Lactobacillus group with low concentration(1×10^(7)CFU mL^(−1))was significantly higher than those of other groups.Microbial-mediated functions predicted by PICRUSt showed that‘Cellular Processes’,‘Metabolism’and‘Organismal Systems’pathways significantly increased in groups of Bacillus subtilis and Lactobacillus group with low concentration.The results showed that two types of probiotics with different concentrations have other effects on the structure,richness and function of intestinal microbes.By searching the literature and conducting pre-experiments,we forecasted the short time of breeding under the probiotic environment may not have much effect.The present study for the first time investigated the impact of probiotics on gut microbiota of juvenile HSCs and found them may benefit for the growth and health of HSCs.
基金the Scientific Research Project of Huaqiao University(No.605-50X18005)Guangxi Bagui Youth Scholars ProgrammeGuangxi Recruitment Program of 100 Global Experts。
文摘Knowledge of dietary compositions is essential to the recovery of the dwindling populations of horseshoe crabs in China.The feeding habits of Tachypleus tridentatus and Carcinoscorpis rotundicauda of Pearl Bay in southwestern China were studied by stable isotope analysis.Hemolymph samples of the two species were obtained from two age groups living in different habitats(inner,central,and outer Bay).In addition,their potential food source samples were collected in May 2019.Results showed that the mean values ofδ^(13)C andδ^(15)N in C.rotundicauda individuals ranged from−19.01‰to−16.47‰and from 10.49‰to 13.5‰,respectively,and those of T.tridentatus ranged from−19.12‰to−14.96‰and from 8.78‰to 13.48‰,respectively.These values indicated that the horseshoe crabs have a wide variety of food sources and therefore are highly omnivorous.No remarkably correlations were found betweenδ^(13)C andδ^(15)N values and individual widths in the two species.Thirteen potential food sources were selected,in which Sipunculus nudus,Batillaria zonalisi,and Ulva lactuca contributed largely to the dietary compositions of the two species of horseshoe crabs.No significant correlation was found between the feeding habits and habitat geochemical characteristics of the horseshoe crabs.All these results possibly indicate the high diversity of their food sources and the indiscriminate dietary compositions of the two Asian horseshoe crabs.
基金Supported by the Conservation of Horseshoe Crabs in Hong Kong:Artificial Breeding and Public Awareness by Ocean Park Conservation Foundation Hong Kong (No. PJ 9230048)
文摘The AFLP(amplified fragment length polymorphism) technique was used to analyze and compare the genetic diversity of Tachypleus tridentatus from three south-eastern coastal sites of China(Pingtan,Hong Kong and Beihai).Eight pairs of primers generated 361 loci,including 285 polymorphic loci.The ratio of polymorphic loci was 96.97%.Nei's genetic diversity index was 0.420 8 and the Shannon information index was 0.607 5,both of which were higher than that reported for many other arthropods.These results show that the genetic diversity detected was mainly caused by individual differences within a population.Genetic distance showed that the rational division of the three geographic populations of T.tridentatus along the south-eastern coast of China was not significant,in which the genetic distance was not proportional to the geographic distance.All three horseshoe crab populations may belong to a large group,and had a high degree of genetic similarity.The high level of genetic diversity obtained from the present AFLP analysis may be due to the large effective population size of the species in Chinese waters.
基金the Scientific Research Project of Huaqiao University(No.605-50X18005)the Guangxi BaGui Youth Scholars Programthe Guangxi Recruitment Program of 100 Global Expert。
文摘Transcriptome assemblies for the stomach,midgut,and fecal mucosa of Tachypleus tridentatus and Carcinoscorpius rotundicauda are reported for the first time in this study.Genome assembly resulted in 373069 unigenes with an N50 of 1314,while transcriptome assembly resulted in 736378 unigenes and an N50 of 2121.The annotated unigenes showed the highest similarity to fishes,amphibians,and reptiles,with most unigenes closely related to metabolism,translation,biogenesis,signal transduction,energy production,immune response,and secretion.Unigenes(4768)were mapped to KEGG pathways,and the most enriched pathways were involved in translation,environmental information signal processing,metabolism,endocrine system,immune system,nervous system,and varying metabolism.Totally 65889,2001,and 7162 differentially expressed genes(DEGs)were identified in the stomach,midgut,and fecal mucosa between the two horseshoe crab species,respectively.Compared with C.rotundicauda,99.95%of the DEGs in the T.tridentatus stomach were down-regulated,while 99.97%of the DEGs of T.tridentatus fecal mucosa and 55.42%of the DEGs of the T.tridentatus midgut were up-regulated.Most midgut DEGs were involved in hydrolase activity,protein metabolism,and cell cytoplasm,while most stomach and fecal mucosa DEGs were involved in catalytic activity and primary metabolic processes.Most stomach DEGs were assigned to the cellular component in cellular macromolecular complexes,while most fecal mucosa DEGs were assigned to the cellular component in cell and cell parts.These results will benefit the investigation of the molecular mechanisms of the digestive tract related to the feeding habits and environmental traces of horseshoe crabs.
基金F5 Subject from Science and Technology Department of Fujian Province under contract No. 2008F5038the Open Foundation from Ocean Fishery Science and Technology in the Most Important Subjects of Zhejiang under contract No.20100210
文摘Population genetic structure and historical demography of Chinese horseshoe crab (T.tridentatus)along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit Ⅰ (COI) fragment.The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province,Meizhou and Zhangpu in Fujian Province,Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province.Sequence variation was relatively low with a total of seven transitions observed.In all localities,Haplotype H3 was the dominant type observed among eight haplotypes defined previously,and was at the center of radiation in Median-Joining network.The prolonged star-like network suggests a signature of population expansions.The level of diversity was low in total,with haplotype diversity ( Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.00118,respectively.The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations.Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion.The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.
基金This research was supported by the National Natural Science Foundation of China(41706183,41901226)the Guangxi Natural Science Foundation(2017GXNSFBA198181)the Guangxi BaGui Youth Scholars Program,the Guangxi Recruitment Program of 100 Global Experts,and the Guangxi Postdoctoral Innovation Program.
文摘Horseshoe crabs,the most well-known example of“living fossils”,are iconic and ecologically important macroinvertebrates in coastal and estuarine ecosystems.Their blood is a crucial resource for manufacturing Limulus or Tachypleus amebocyte lysate to detect bacterial endotoxins or fungal contamination in drug and medical devices.An enhanced understanding of their ecological roles and trophic interactions in the food webs is fundamental to facilitate resource management for the declining populations in Asia.Foraging information of the Asian species,however,is mainly derived from preliminary,scattered reports from a limited number of study locations.In this study,resource utilization,trophic niche dynamics,and trophic interaction of the juvenile tri-spine horseshoe crab,Tachypleus tridentatus(instars 1–12,approximately 0.5–8 years old)across ontogeny was assessed in diversified nursery habitats along the northern Beibu Gulf,China,using carbon and nitrogen stable isotopes.Our results suggest that:(i)T.tridentatus are ecological generalists given the vast range of carbon isotopic values and trophic niche width estimates exhibited between multiple instar groups;(ii)juvenile T.tridentatus across most habitat types predominantly assimilated energy from a variety of basal production sources in the food web,but primarily depended on sedimentary organic matter and seagrass resource pools;(iii)ontogenetic shifts in juvenile dietary proportions were evident,with decreased reliance on sedimentary organic matter,coupled with increased reliance on benthic macroinvertebrate grazers,detritivores,and omnivores with age;and(iv)nearly all juvenile instars occupied similar trophic positions in the food web with slight shifts in trophic position present with increasing size.Our findings indicate that resource availability and ontogenetic diet shifts strongly influence horseshoe crab trophic dynamics,and age should be accounted when formulating habitat conservation measures based on resource use for Asian horseshoe crabs.
文摘Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals,including aquatic animals.As the haemolymph of horseshoe crabs(Tachypleus)contains broad ranges of bioactive compounds,we have explored the in vivo immunostimulating potential of amoebocyte lysate and plasma using a fish model.Indian major carp,Labeo rohita,yearlings were injected intraperitoneally with two doses of lysate and plasma at 50 and 100µg protein per fish.No abnormalities and/or mortalities were recorded in any group.L.rohita injected with 50µg lysate and 100µg plasma protein showed significant enhancement(P<0.01)of various haematological and immunological parameters.There was a significant rise in the total protein and globulin content,myeloperoxidase and respiratory burst activity following injection with 50µg lysate and 100µg plasma protein.The agglutinating and haemagglutinating activities were increased albeit not significantly(P>0.01)in any groups.On the contrary,a significantly high hemolysin titre was recorded in fish that received 100µg plasma protein.Following challenge with Aeromonas hydrophila,both lysate and plasma protein(s)cross protected the fish after 30 days.The highest survival(50%)was recorded in group injected with 50µg lysate protein,followed by 45%in both 100µg lysate and plasma protein injected groups.
基金the National Natural Science Foundation of China(Nos.32060129,42067038)the Beibu Gulf Ocean Development Research Center under Key Research Base of Humanities and Social Sciences in Guangxi Universities+1 种基金the Guangxi Bagui Youth Scholars Programmethe Guangxi Recruitment Program of 100 Global Experts。
文摘Identification,protection and restoration of spawning habitats are vital for protecting the depleted species.Asian horseshoe crabs are ecologically important macroinvertebrates in coastal and estuarine ecosystems.However,their spawning habitat studies were limited to several reports in tropical regions,possibly due to the lack of modified survey methods,particularly in habitats with a lower density of spawning adults,and/or intermingled with anthropogenic structures.In this study,the year-round egg distribution and spawning habitat baselines of Carcinoscorpius rotundicauda and Tachypleus tridentatus were determined in the northern Beibu Gulf,China.Our findings demonstrated that the peak spawning occurred in June–July and ceased in November–January when the average water temperature dropped below 20℃.Egg aggregations were found<10 cm beneath the sediment surface with regular tidal inundation,regardless of seasonal changes,in the vicinity of natural and artificial structures with elevated,mildly sloping substratum within the high tide zones.The nests were characterized by medium-sized sediment grains(0.5–0.9 mm),high temperatures(31–34℃),low water contents(0.8%–0.9%),and total organic carbon contents(0.5%–0.7%),which might maximize the hatching success.The identified nesting beaches were close to nursery habitats for juveniles,and tidal creeks were present as the possible corridor connecting these two important habitats through the dominant mangrove forests.The findings provide valuable insights in the scope of spawning behavior and nest-site selection of Asian horseshoe crabs under a mixture of natural and artificial structures,which could benefit future management efforts for the exploited spawning populations.
基金This project was supported by a grant from National Natural Sciences Foundation(No.39870872)and Foundation of Public Healthy Ministry of China(No.98-2-110).
文摘The anti-endotoxic effect of syringic acid (SA) isolated from Radix Isatidis (Banlangen, BLG) was studied. SA was extracted and isolated from BLG and diluted into 1 % solution. The content of SA-pretreated endotoxin (ET) was quantitatively determined using Limulus test. The ability of fever induction of ET pretreated with SA was measured using endotoxin-induced fever test in rabbits. The LPS-induced death in mice pretreated with and without SA was compared. Results showed that after pretreatment with SA, 83. 16 % of ET was destroyed, the ET-induced fever in rabbits relieved markedly and the LPS-induced death rate in mice dropped from 68 % to 20 %. It was concluded that SA isolated from BLG had anti-endotoxic effects.
基金supported in part by China Foundation for the Author of National Excellent Doctoral Dissertation(No.200338)Shaanxi Province Science and Technology Program(No.2010K16-04)+1 种基金the Fundamental Research Funds for the Central Universities (Nos.2009xjtujc18,xjj20100160)Guanghua Foundation for Medicine Innovation Research of China(No.0203419)
文摘The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentrations of bacterial endotoxin （1 EU/mL, 0.5 EU/mL and 0.25 EU/mL） were treated by LTP for different time （20 s, 40 s and 60 s）. Tachypleus amebocyte lysate （TAL） method was employed to detect the concentration variation of bacterial endotoxin before and af- ter the plasma treatment, and endotoxic shock mice model was used to evaluate the inactivation effects of LTP on endotoxin for further study. Experimental results demonstrated that, DBD plasma can inactivate the bacterial endotoxin quickly and effectively, and when the LTP treatment time was increased, the concentrations of bacterial endotoxin decreased gradually （after 60 s plasma treatment, its inactivation effect was beyond the Chinese pharmacopoeia standard）, and the average survival time of mice gradually extended. The possible inactivation mechanisms are proposed to be related to reactive oxygen species （ROSs）.
基金the Basic Research Fund of Guangxi Academy of Sciences(No.2020YBJ706)the National Natural Science Foundation of China(No.32060129)+3 种基金the Guangxi Natural Science Foundation(No.2018 GXNSFBA281071)the Guangxi Science and Technology Base and Talent Project(No.2021AC19355)the Guangxi Ba Gui Youth Scholar Programthe Guangxi Recruitment Program of 100 Global Experts。
文摘Bycatch poses a severe challenge to global fishery management.Although studies have focused on marine megafauna bycatch,research on relevant issues regarding invertebrates is limited,particularly for the threatened horseshoe crabs.In this study,the distribution of fishing gears and the bycatch intensity of Asian horseshoe crabs in the intertidal zones of the northern Beibu Gulf that harbors the most abundant juvenile Asian horseshoe crabs populations in China were evaluated.Seven intertidal nursery habitats for Tachypleus tridentatus and Carcinoscorpius rotundicauda were surveyed from May to July in 2021.A transect that crossed the tidal creeks and tidal flats between the high tide embankment/vegetation and low tide line of a given habitat was surveyed during the ebb tides.The type,number,and GPS of fishing gears were recorded when sighted,and the number and prosomal width of each horseshoe crab species were measured.Bycatch intensities differed among habitats,ranging from 0.3 to 18.4 and 1.2 to 22.7 individuals per kilometer of transect for T.tridentatus and C.rotundicauda,respectively.Among the three identified fishing gear types,ground cages and stick net sets caused a stronger bycatch pressure on these two species.Most T.tridentatus bycatch and C.rotundicauda bycatch were large individuals in late juvenile and adult stages.Therefore,the ground cages and stick net sets along/near the tidal creeks,mangrove fringe,and low tide line should be regulated and removed to ensure the functionality of the intertidal zone as the spawning corridor and nursery habitat of Asian horseshoe crabs.
