Chaetoceros Ehrenberg is one of the most diverse genera of planktonic diatoms.The species in section Chaetoceros are characterized by cells and setae having numerous chloroplasts and being widely distributed.However,t...Chaetoceros Ehrenberg is one of the most diverse genera of planktonic diatoms.The species in section Chaetoceros are characterized by cells and setae having numerous chloroplasts and being widely distributed.However,the delimitations of some species are problematic because of limited morphological information in the classical descriptions.Monoclonal strains of the section Chaetoceros were established,morphological features were studied using light and electron microscopy,and the hypervariable D 1-D 3 region of the nuclear ribosomal large subunit gene was sequenced to address phylogenetic relationships.Fifteen species belonging to the section Chaetoceros were recorded,including two new species,C.hainanensis sp.nov.and C.tridiscus sp.nov.Chaetoceros hainanensis was characterized by straight chains,narrowly lanceolate to hexagonal apertures,sibling setae diverging in nearly right angles,stipule-shaped spines on terminal setae and arrowhead-shaped spines on intercalary setae.C.tridiscus had short straight chains,narrowly lanceolate apertures,arrowhead-shaped spines and circular poroids arranged in a grid pattern on terminal and intercalary setae.The phylogenetic analyses revealed six groups formed by 19 species within the section Chaetoceros,which was found to be monophyletic.The subdivision of the section is still not well understood.The morphological characters within each group varied considerably and molecular information on more species are needed to enrich the phylogenetic profiling.展开更多
One new marine oligotrich ciliate, Omegastrombidium hongkongense n. sp., was isolated from a bloom of Noctiluca scuntillans near Port Shelter, Hong Kong. The morphology and infraciliature of this new species were stud...One new marine oligotrich ciliate, Omegastrombidium hongkongense n. sp., was isolated from a bloom of Noctiluca scuntillans near Port Shelter, Hong Kong. The morphology and infraciliature of this new species were studied on both living and protargol-stained specimens. Its phylogenetic position was discussed based on the sequence of the small subunit r RNA gene. O. hongkongense is different from its congeners with special characters. The cells are usually heart-shaped, and the cell size usually is(20–35) ×(20–30) μm in vivo. Its deep buccal cavity extends obliquely to about 1/2 of cell length. It shows prominent apical protrusion. The adoral zone of membranelles is divided into 17–19 collar membranelles and four buccal membranelles. It has one ball-like macronucleus. The girdle kinety forms a closed loop which obliquely surrounds the body. The ventral kinety and thigmotactic membranelles are not observed. The SSU r RNA sequence of O. hongkongense was close to those of Strombidium paracalkinsi and Varistrombidium kelum with approximately 99% similarity. In the phylogenetic trees, O. hongkongense can be grouped with O. elegans and V. kielum species with very low support(16% ML).展开更多
Ecotoxic effects of antibiotics or ammonium have been confirmed independently in aquatic animals,but few studies have investigated their combined effects.In aquaculture ecosystems,these pollutants frequently coexist,a...Ecotoxic effects of antibiotics or ammonium have been confirmed independently in aquatic animals,but few studies have investigated their combined effects.In aquaculture ecosystems,these pollutants frequently coexist,and often in high concentrations.In this study,the combined effects of antibiotic nitrofurazone and NH4 Cl on the population dynamics and growth rates of two species of ciliated protists,Euplotes vannus and Pseudokeronopsis rubra,were investigated.Profiles of the dose-responses were visualized,and interactions between the two pollutants were quantified by the response surface method(RSM).Results showed that 1)the dynamics of the population growth differed significantly between the testd ciliates and varied with the concentrations of the pollutants;2)the relative growth rate(RGR)of both ciliates decreased significantly with increased pollutant concentrations,while the difference in RGR between the two ciliates was not significant;3)RSM analysis demonstrated an additive effect of nitrofurazone and NH4 Cl on the RGR in both ciliates.In brief,ecotoxic effects can be caused by nitrofurazone and ammonium independently on the two test ciliates,and such effects can be strengthened when they present at the same time.These findings offer a valuable reference for evaluating combined ecotoxic effects caused by multiple pollutants in aquaculture ecosystems.展开更多
As one of the main groups of marine planktonic protozoa,oligotrich ciliates have shown a high biodiversity.Recently,a new aloricate oligotrich ciliate,Strombidium pseudorapulum sp.n.was isolated from coastal waters of...As one of the main groups of marine planktonic protozoa,oligotrich ciliates have shown a high biodiversity.Recently,a new aloricate oligotrich ciliate,Strombidium pseudorapulum sp.n.was isolated from coastal waters of southeast China.The living morphology and infraciliature of this species were studied using live cell observation and protargol impregnation.Strombidium pseudorapulum sp.n.differs from its congeners by having a radish-like body with a bumped anterior end and an elongated tail-like posterior end,possessing a red‘eyespot’in apical protrusion of cell,adoral zone of membranelles composed of 12–16 collar and 9–12 buccal membranelles,one spindle-shaped macronucleus,girdle kinety in anterior 2/5 of cell with 45–60 densely spaced dikinetids,and ventral kinety occupying about the posterior 1/3 of the cell with 16–19 dikinetids.Strombidium pseudorapulum sp.n.clusters together with those species having‘eyespot’in apical protrusion in the phylogenetic tree based on the small subunit rRNA gene sequence.It is a sister species of S.cuneiforme with 31 unmatched nucleotides between their SSU rRNA gene sequences.展开更多
Although the taxonomy of oligotrich ciliates has been widely investigated,yet the species diversity remains poorly known.We newly designed a pair of oligotrich-specific LSU rDNA primers covering the 600-bp D1/D2 regio...Although the taxonomy of oligotrich ciliates has been widely investigated,yet the species diversity remains poorly known.We newly designed a pair of oligotrich-specific LSU rDNA primers covering the 600-bp D1/D2 region,and it was effective for detecting oligotrich species.Using the primers,we constructed the cloning libraries to investigate the species diversity of oligotrichs in the northern coastal waters of the South China Sea.In total,165 oligotrich sequences were obtained from five widely separated sampling sites.Sixty operational taxonomic units(OTUs)were obtained at 99%similarity threshold,and low-abundance OTUs with no more than two sequences contributed most of these(about 78%).Our findings are consistent with previous morphological studies,Strombidium was found the most abundant and widely distributed genus in this area.In addition,the BLAST search in the NCBI database resulted in 95%OTUs matching with named oligotrich species in similarity below 99%.Therefore,oligotrich morphospecies diversity has been underestimated as low-abundance species,and the LSU rDNA oligotrich sequence database needs to be better promoted.展开更多
This study aimed to investigate the application of cottonseed protein concentrate(CPC)in Chinese mitten crabs(Eriocheir sinensis).First,the apparent digestibility coefficient(ADC)of CPC,fish meal and soybean meal were...This study aimed to investigate the application of cottonseed protein concentrate(CPC)in Chinese mitten crabs(Eriocheir sinensis).First,the apparent digestibility coefficient(ADC)of CPC,fish meal and soybean meal were compared in crabs(21.72±0.33 g).The protein ADC of CPC was 90.42%,which was signifi-cantly higher than that of soybean meal(83.16%)(P<0.05).The ADC of Phe,Cys and Glu of CPC were significantly higher than those of fish meal,while the ADC of Ile,Leu,Lys,Met,Thr and Ala of CPC were significantly lower(P<0.05).Second,we investigated the effects of fish meal substitution by CPC on growth performance,free amino acid profile,and expression of genes related to nutrient metabolism in crabs.Six diets were formulated by replacing 0%,15%,30%,45%,60%and 75%fish meal with CPC,namely FM,CPC15,CPC30,CPC45,CPC60,and CPC75.A total of 630 crabs(1.68±0.00 g)were randomly divided into 18 tanks(3 tanks per group)and fed 3 times daily for 9 weeks.Results showed that CPC75 group significantly reduced growth performance,feed conversion efficiency,and free Ile,Leu,Lys,Met,and Thr contents in muscle(P<0.05).The contents of free amino acids(Arg,His,Ile,Leu,Lys,Met,Phe,Thr,Val,Ala,Cys,Glu,Gly,Ser and Tyr)in hepatopancreas decreased linearly with the increase of dietary CPC level(P<0.05).The substitution of more than 45%fish meal with CPC significantly decreased the concen-tration of delicious amino acids(Ala,Glu and Gly)in hepatopancreas(P<0.05),which might adversely affect crab flavor.The expression of genes related to antioxidant capacity,protein transport,TOR pathway and lipid metabolism was significantly downregulated by increasing dietary CPC level(P<0.05).In conclusion,based on the quadratic regression analysis of FCR and PER,the optimal replacement levels of fish meal with CPC in crab diet containing 35%fish meal were 32.36%and 35.38%,respectively.It is recommended that Ile,Leu and Thr be supplemented in addition to Met and Lys in the application of CPC.展开更多
Urbanization-driven biotic homogenization has been recorded in various ecosystems on local and global scales;however,it is largely unexplored in developing countries.Empirical studies on different taxa and bioregions ...Urbanization-driven biotic homogenization has been recorded in various ecosystems on local and global scales;however,it is largely unexplored in developing countries.Empirical studies on different taxa and bioregions show conflicting results(i.e.biotic homogenization vs.biotic differentiation);the extent to which the community compo-sition changes in response to anthropogenic disturbances and the factors governing this process,therefore,require elucidation.Here,we used a compiled database of 760 bird species in China to quantify the multiple-siteβ-diversity andfitted distance decay in pairwiseβ-diversities between natural and urban assemblages to assess whether urban-ization had driven biotic homogenization.We used generalized dissimilarity models(GDM)to elucidate the roles of spatial and environmental factors in avian community dissimilarities before and after urbanization.The multiple-siteβ-diversities among urban assemblages were markedly lower than those among natural assemblages,and the distance decays in pairwise similarities in natural assemblages were more rapid.These results were consistent among taxonomic,phylogenetic,and functional aspects,supporting a general biotic homogenization driven by ur-banization.The GDM results indicated that geographical distance and temperature were the dominant predictors of avian community dissimilarity.However,the contribution of geographical distance and climatic factors decreased in explaining compositional dissimilarities in urban assemblages.Geographical and environmental distances ac-counted for much lower variations in compositional dissimilarities in urban than in natural assemblages,implying a potential risk of uncertainty in model predictions under further climate change and anthropogenic disturbances.Our study concludes that taxonomic,phylogenetic,and functional dimensions elucidate urbanization-driven biotic homogenization in China.展开更多
Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especi...Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especially insights from soil chemical properties and soil microbial communities.Methods In a field experiment,soil microbial community,potassium-solubilizing bacteria,phosphorus-solubilizing bacteria,enzyme activities,and light-saturated photosynthetic rate were measured in invasive Sphagneticola trilobata and its hybrid with native Sphagneticola calendulacea in 2 years.Important Findings In general,soil dissolved organic carbon and the biomass of phosphorus-solubilizing bacteria were significantly higher under the hybrid treatment than S.trilobata and S.calendulacea.However,there were no significant differences in acid phosphatase,total PLFAs,bacterial PLFAs,fungi PLFAs,cellulase,and urase in these treatments.The hybrids had significantly higher light-saturated photosynthetic rate,photosynthetic nitrogen-,phosphorus-,potassium-use efficiencies than the invasive S.trilobata,but no significant difference with S.calendulacea.The total biomass and root biomass of hybrids were higher than S.calendulacea.Our results indicate that the hybrids species have a higher invasive potential than S.calendulacea,which may aggravate the local extinction of S.calendulacea in the future.展开更多
Recent studies have revealed a high diversity of pleurostomatid ciliates in brackish habitats. Here, a novel species, Pseudolitonotus spirelis gen. et sp. n., isolated from a mangrove wetland of southern China, was in...Recent studies have revealed a high diversity of pleurostomatid ciliates in brackish habitats. Here, a novel species, Pseudolitonotus spirelis gen. et sp. n., isolated from a mangrove wetland of southern China, was investigated based on living observation, protargol staining, and molecular analyses. The new genus Pseudolitonotus gen. n. is characterized by the last left somatic kinety (LKn) being shortened and none of the right somatic kineties extending to the anterior end of the cell, thus distinguishing it from all known pleurostomatid genera. The type species, Pseudolitonotus spirelis sp. n., is characterized by the possession of two macronuclear nodules, 11–15 right and 7–9 left kineties, a single contractile vacuole subterminally located, extrusomes evenly spaced along the entire ventral margin and some forming an “apical group”, two types of cortical granules, and the bottom of the oral slit invariably being twisted. Litonotus gracilis (Pan et al. Eur J Protistol 51:494–506, 2015) is believed to be another member of this new genus as its LKn and right somatic kineties are all shortened. Hence, a new combination, Pseudolitonotus gracilis (Pan et al., 2015) comb. n., is suggested and its diagnosis is improved. Molecular phylogenetic analyses based on SSU rDNA sequence data reveal that Pseudolitonotus gen. n. is monophyletic and groups with Apolitonotus (Pan et al. J Eukaryot Microbiol 67:252–262, 2020) of the family Protolitonotidae (Wu et al. Zool Scr 46:245–253, 2017). However, the familial assignment of this new genus is uncertain based on current data.展开更多
Xanthophyll has multiple physiological functions to improve the quality of farmed animals.The present study aimed to investigate the effects of xanthophyll on the growth performance,antioxidation,immunity,pigmentation...Xanthophyll has multiple physiological functions to improve the quality of farmed animals.The present study aimed to investigate the effects of xanthophyll on the growth performance,antioxidation,immunity,pigmentation and meat quality of southern catfish(Silurus soldatovi meridionalis Chen).Juvenile southern catfish(18.35±0.04 g)were randomly allocated into 24 cages(30 juveniles per cage),and fed diets with different dietary xanthophyll levels(at 14,42,80,108,126 and 152 mg/kg,dry matter of diet)twice daily for 8 weeks.Results indicated that the diet with 80 mg/kg xanthophyll induced a higher specific growth rate(SGR),feed efficiency ratio and protein productive value.Moreover,the 80 mg/kg xanthophyll diet also increased complement 3,immunoglobulin M(IgM)and lysozyme content more than the other groups.The mRNA expression level of inflammation-related genes and antioxidant enzyme activities further confirmed the effects of 80 mg/kg dietary xanthophyll on improving immune response.The present study also found that the 126 mg/kg xanthophyll diet significantly enhanced the content of total carotenoids and xanthophyll,hydroxyproline,collagen and amino acid in muscle.The diet with 126 mg/kg xanthophylls also induced lower drip loss,thawing loss,centrifugal loss,cooking loss and higher muscle adhesiveness,cohesiveness,springiness,gumminess and chewiness than the other treatments.In conclusion,quadratic regression model analysis based on SGR and IgM revealed that the optimum xanthophyll level in the diet was 86.78 and 84.63 mg/kg,respectively.Moreover,broken line regression analysis based on xanthophyll content in dorsal skin and chewiness in muscle demonstrated that the optimal xanthophyll level was between 89.73 and 108.66 mg/kg in the diet of southern catfish(S.soldatovi meridionalis Chen).展开更多
Adaptations of ciliates to hypoxic environments have arisen independently several times.Studies on mitochondrion-related organelle(MRO)metabolisms from distinct anaerobic ciliate groups provide evidence for understand...Adaptations of ciliates to hypoxic environments have arisen independently several times.Studies on mitochondrion-related organelle(MRO)metabolisms from distinct anaerobic ciliate groups provide evidence for understanding the transitions from mitochondria to MROs within eukaryotes.To deepen our knowledge about the evolutionary patterns of ciliate anaerobiosis,mass-culture and single-cell transcriptomes of two anaerobic species,Metopus laminarius(class Armophorea)and Plagiopyla cf.narasimhamurtii(class Plagiopylea),were sequenced and their MRO metabolic maps were compared.In addition,we carried out comparisons using publicly available predicted MRO proteomes from other ciliate classes(i.e.,Armophorea,Litostomatea,Muranotrichea,Oligohymenophorea,Parablepharismea and Plagiopylea).We found that single-cell transcriptomes were similarly comparable to their mass-culture counterparts in predicting MRO metabolic pathways of ciliates.The patterns of the components of the MRO metabolic pathways might be divergent among anaerobic ciliates,even among closely related species.Notably,our findings indicate the existence of group-specific functional relics of electron transport chains(ETCs).Detailed group-specific ETC functional patterns are as follows:full oxidative phosphorylation in Oligohymenophorea and Muranotrichea;only electron-transfer machinery in Armophorea;either of these functional types in Parablepharismea;and ETC functional absence in Litostomatea and Plagiopylea.These findings suggest that adaptation of ciliates to anaerobic conditions is group-specific and has occurred multiple times.Our results also show the potential and the limitations of detecting ciliate MRO proteins using single-cell transcriptomes and improve the understanding of the multiple transitions from mitochondria to MROs within ciliates.展开更多
The morphology and molecular phylogeny of freshwater pleurostomatid ciliates are insufficiently explored.In the present study,we investigated three new Amphileptus species discovered in Lake Weishan and its vicinity,n...The morphology and molecular phylogeny of freshwater pleurostomatid ciliates are insufficiently explored.In the present study,we investigated three new Amphileptus species discovered in Lake Weishan and its vicinity,northern China,using standard alpha-taxonomic methods.Amphileptus paracarchesi sp.nov.is characterized by a lateral fossa(groove)in the posterior body portion,four macronuclear nodules,contractile vacuoles distributed along the dorsal margin,and 4-6 left and 44-50 right somatic kineties.Amphileptus pilosus sp.nov.differs from congeners by having 4-14 macronuclear nodules,numerous contractile vacuoles scattered throughout the cytoplasm,and 22-31 left and 35-42 right somatic kineties.Amphileptus orientalis sp.nov.is characterized by two ellipsoidal macronuclear nodules,three ventral contractile vacuoles,and about four left and 31-35 right somatic kineties.Phylogenetic analyses of nuclear small subunit ribosomal DNA(SSU rDNA)sequences indicate that the family Amphileptidae might be monophyletic while the genus Amphileptus is paraphyletic,as Pseudoamphileptus macrostoma robustly groups with Amphileptus sp.Although deep phylogenetic relationships of amphileptids are poorly resolved,multiple well-delimited species groups are recognizable within the genus Amphileptus.展开更多
基金Supported by the Joint Fund of National Natural Science Foundation of China and Chinese Shandong Province(No.U 2106205)the National Natural Science Foundation of China(No.32170206)the National Key Research and Development Program of China(No.2022YFC3105201)。
文摘Chaetoceros Ehrenberg is one of the most diverse genera of planktonic diatoms.The species in section Chaetoceros are characterized by cells and setae having numerous chloroplasts and being widely distributed.However,the delimitations of some species are problematic because of limited morphological information in the classical descriptions.Monoclonal strains of the section Chaetoceros were established,morphological features were studied using light and electron microscopy,and the hypervariable D 1-D 3 region of the nuclear ribosomal large subunit gene was sequenced to address phylogenetic relationships.Fifteen species belonging to the section Chaetoceros were recorded,including two new species,C.hainanensis sp.nov.and C.tridiscus sp.nov.Chaetoceros hainanensis was characterized by straight chains,narrowly lanceolate to hexagonal apertures,sibling setae diverging in nearly right angles,stipule-shaped spines on terminal setae and arrowhead-shaped spines on intercalary setae.C.tridiscus had short straight chains,narrowly lanceolate apertures,arrowhead-shaped spines and circular poroids arranged in a grid pattern on terminal and intercalary setae.The phylogenetic analyses revealed six groups formed by 19 species within the section Chaetoceros,which was found to be monophyletic.The subdivision of the section is still not well understood.The morphological characters within each group varied considerably and molecular information on more species are needed to enrich the phylogenetic profiling.
基金supported by the National Natural Science Foundation of China(No.31301868)the Hong Kong Research Grants Council(Nos.GRF 661610 and 661912)+2 种基金the Hong Kong Scholar Programme(No.HKSP13SC03)NSFC-Guangdong Province Joint Foundation(No.U1301 235)Natural Science Foundation of Guangdong Pro-vince(No.S2013040013192)
文摘One new marine oligotrich ciliate, Omegastrombidium hongkongense n. sp., was isolated from a bloom of Noctiluca scuntillans near Port Shelter, Hong Kong. The morphology and infraciliature of this new species were studied on both living and protargol-stained specimens. Its phylogenetic position was discussed based on the sequence of the small subunit r RNA gene. O. hongkongense is different from its congeners with special characters. The cells are usually heart-shaped, and the cell size usually is(20–35) ×(20–30) μm in vivo. Its deep buccal cavity extends obliquely to about 1/2 of cell length. It shows prominent apical protrusion. The adoral zone of membranelles is divided into 17–19 collar membranelles and four buccal membranelles. It has one ball-like macronucleus. The girdle kinety forms a closed loop which obliquely surrounds the body. The ventral kinety and thigmotactic membranelles are not observed. The SSU r RNA sequence of O. hongkongense was close to those of Strombidium paracalkinsi and Varistrombidium kelum with approximately 99% similarity. In the phylogenetic trees, O. hongkongense can be grouped with O. elegans and V. kielum species with very low support(16% ML).
基金supported by the National Natural Science Foundation of China(Nos.31971519,31430077,41476128)in part by a grant from the Dedicated Fund for Promoting High-Quality Economic Development in Guangdong Province(Marine Economic Development Project:GDOE(2019)A23)。
文摘Ecotoxic effects of antibiotics or ammonium have been confirmed independently in aquatic animals,but few studies have investigated their combined effects.In aquaculture ecosystems,these pollutants frequently coexist,and often in high concentrations.In this study,the combined effects of antibiotic nitrofurazone and NH4 Cl on the population dynamics and growth rates of two species of ciliated protists,Euplotes vannus and Pseudokeronopsis rubra,were investigated.Profiles of the dose-responses were visualized,and interactions between the two pollutants were quantified by the response surface method(RSM).Results showed that 1)the dynamics of the population growth differed significantly between the testd ciliates and varied with the concentrations of the pollutants;2)the relative growth rate(RGR)of both ciliates decreased significantly with increased pollutant concentrations,while the difference in RGR between the two ciliates was not significant;3)RSM analysis demonstrated an additive effect of nitrofurazone and NH4 Cl on the RGR in both ciliates.In brief,ecotoxic effects can be caused by nitrofurazone and ammonium independently on the two test ciliates,and such effects can be strengthened when they present at the same time.These findings offer a valuable reference for evaluating combined ecotoxic effects caused by multiple pollutants in aquaculture ecosystems.
基金the National Natural Science Foundation of China(No.31761133001)the Guangdong MEPP Fund(No.GDOE(2019)A23)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0405)Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences(No.ISEE 2018PY01).
文摘As one of the main groups of marine planktonic protozoa,oligotrich ciliates have shown a high biodiversity.Recently,a new aloricate oligotrich ciliate,Strombidium pseudorapulum sp.n.was isolated from coastal waters of southeast China.The living morphology and infraciliature of this species were studied using live cell observation and protargol impregnation.Strombidium pseudorapulum sp.n.differs from its congeners by having a radish-like body with a bumped anterior end and an elongated tail-like posterior end,possessing a red‘eyespot’in apical protrusion of cell,adoral zone of membranelles composed of 12–16 collar and 9–12 buccal membranelles,one spindle-shaped macronucleus,girdle kinety in anterior 2/5 of cell with 45–60 densely spaced dikinetids,and ventral kinety occupying about the posterior 1/3 of the cell with 16–19 dikinetids.Strombidium pseudorapulum sp.n.clusters together with those species having‘eyespot’in apical protrusion in the phylogenetic tree based on the small subunit rRNA gene sequence.It is a sister species of S.cuneiforme with 31 unmatched nucleotides between their SSU rRNA gene sequences.
基金Supported by the National Natural Science Foundation of China(Nos.31772440,31430077,41576124,31761133001)the Pearl River Science and Technology Nova Program of Guangzhou(No.201610010162) to YZ+1 种基金Guangdong MEPP Fund(No.GDOE(2019)A23)the Special Support Program of Guangdong Province to YZ
文摘Although the taxonomy of oligotrich ciliates has been widely investigated,yet the species diversity remains poorly known.We newly designed a pair of oligotrich-specific LSU rDNA primers covering the 600-bp D1/D2 region,and it was effective for detecting oligotrich species.Using the primers,we constructed the cloning libraries to investigate the species diversity of oligotrichs in the northern coastal waters of the South China Sea.In total,165 oligotrich sequences were obtained from five widely separated sampling sites.Sixty operational taxonomic units(OTUs)were obtained at 99%similarity threshold,and low-abundance OTUs with no more than two sequences contributed most of these(about 78%).Our findings are consistent with previous morphological studies,Strombidium was found the most abundant and widely distributed genus in this area.In addition,the BLAST search in the NCBI database resulted in 95%OTUs matching with named oligotrich species in similarity below 99%.Therefore,oligotrich morphospecies diversity has been underestimated as low-abundance species,and the LSU rDNA oligotrich sequence database needs to be better promoted.
基金funded by National Key R&D Program of China(2018YFD0900400)Guangzhou Science and Technology Planning Project(2023E04J1247).
文摘This study aimed to investigate the application of cottonseed protein concentrate(CPC)in Chinese mitten crabs(Eriocheir sinensis).First,the apparent digestibility coefficient(ADC)of CPC,fish meal and soybean meal were compared in crabs(21.72±0.33 g).The protein ADC of CPC was 90.42%,which was signifi-cantly higher than that of soybean meal(83.16%)(P<0.05).The ADC of Phe,Cys and Glu of CPC were significantly higher than those of fish meal,while the ADC of Ile,Leu,Lys,Met,Thr and Ala of CPC were significantly lower(P<0.05).Second,we investigated the effects of fish meal substitution by CPC on growth performance,free amino acid profile,and expression of genes related to nutrient metabolism in crabs.Six diets were formulated by replacing 0%,15%,30%,45%,60%and 75%fish meal with CPC,namely FM,CPC15,CPC30,CPC45,CPC60,and CPC75.A total of 630 crabs(1.68±0.00 g)were randomly divided into 18 tanks(3 tanks per group)and fed 3 times daily for 9 weeks.Results showed that CPC75 group significantly reduced growth performance,feed conversion efficiency,and free Ile,Leu,Lys,Met,and Thr contents in muscle(P<0.05).The contents of free amino acids(Arg,His,Ile,Leu,Lys,Met,Phe,Thr,Val,Ala,Cys,Glu,Gly,Ser and Tyr)in hepatopancreas decreased linearly with the increase of dietary CPC level(P<0.05).The substitution of more than 45%fish meal with CPC significantly decreased the concen-tration of delicious amino acids(Ala,Glu and Gly)in hepatopancreas(P<0.05),which might adversely affect crab flavor.The expression of genes related to antioxidant capacity,protein transport,TOR pathway and lipid metabolism was significantly downregulated by increasing dietary CPC level(P<0.05).In conclusion,based on the quadratic regression analysis of FCR and PER,the optimal replacement levels of fish meal with CPC in crab diet containing 35%fish meal were 32.36%and 35.38%,respectively.It is recommended that Ile,Leu and Thr be supplemented in addition to Met and Lys in the application of CPC.
基金supported by grants from the National Natural Science Foundation of China(grant no.32271733)the Guangdong Basic and Applied Basic Research Foundation(grant no.2023A1515011045)+1 种基金the Science and Technology Projects in Guangzhou(grant no.2023A04J0121)the National College Student Innovation and Entrepreneurship Training Program(grant no.202310574047).
文摘Urbanization-driven biotic homogenization has been recorded in various ecosystems on local and global scales;however,it is largely unexplored in developing countries.Empirical studies on different taxa and bioregions show conflicting results(i.e.biotic homogenization vs.biotic differentiation);the extent to which the community compo-sition changes in response to anthropogenic disturbances and the factors governing this process,therefore,require elucidation.Here,we used a compiled database of 760 bird species in China to quantify the multiple-siteβ-diversity andfitted distance decay in pairwiseβ-diversities between natural and urban assemblages to assess whether urban-ization had driven biotic homogenization.We used generalized dissimilarity models(GDM)to elucidate the roles of spatial and environmental factors in avian community dissimilarities before and after urbanization.The multiple-siteβ-diversities among urban assemblages were markedly lower than those among natural assemblages,and the distance decays in pairwise similarities in natural assemblages were more rapid.These results were consistent among taxonomic,phylogenetic,and functional aspects,supporting a general biotic homogenization driven by ur-banization.The GDM results indicated that geographical distance and temperature were the dominant predictors of avian community dissimilarity.However,the contribution of geographical distance and climatic factors decreased in explaining compositional dissimilarities in urban assemblages.Geographical and environmental distances ac-counted for much lower variations in compositional dissimilarities in urban than in natural assemblages,implying a potential risk of uncertainty in model predictions under further climate change and anthropogenic disturbances.Our study concludes that taxonomic,phylogenetic,and functional dimensions elucidate urbanization-driven biotic homogenization in China.
基金funded by the National Natural Science Foundation of China(41907023,31870374)the China Postdoctoral Science Foundation(2018M643112)and the China Postdoctoral Science Foundation(2018M643112)+1 种基金the State Key Laboratory for Biology of Plant Diseases and Insect Pests(SKLOF201914)supported by Guangdong Province Natural Science Foundation(2017A030313167,2015A030311023).
文摘Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especially insights from soil chemical properties and soil microbial communities.Methods In a field experiment,soil microbial community,potassium-solubilizing bacteria,phosphorus-solubilizing bacteria,enzyme activities,and light-saturated photosynthetic rate were measured in invasive Sphagneticola trilobata and its hybrid with native Sphagneticola calendulacea in 2 years.Important Findings In general,soil dissolved organic carbon and the biomass of phosphorus-solubilizing bacteria were significantly higher under the hybrid treatment than S.trilobata and S.calendulacea.However,there were no significant differences in acid phosphatase,total PLFAs,bacterial PLFAs,fungi PLFAs,cellulase,and urase in these treatments.The hybrids had significantly higher light-saturated photosynthetic rate,photosynthetic nitrogen-,phosphorus-,potassium-use efficiencies than the invasive S.trilobata,but no significant difference with S.calendulacea.The total biomass and root biomass of hybrids were higher than S.calendulacea.Our results indicate that the hybrids species have a higher invasive potential than S.calendulacea,which may aggravate the local extinction of S.calendulacea in the future.
基金supported by the Natural Science Foundation of China(Project Numbers:42076113,31761133001,41576148)supported by the China Postdoctoral Science Foundation(Project Number:2018M640796)the Guangdong Basic and Applied Basic Research Foundation(Project Number:2020A1515111125).
文摘Recent studies have revealed a high diversity of pleurostomatid ciliates in brackish habitats. Here, a novel species, Pseudolitonotus spirelis gen. et sp. n., isolated from a mangrove wetland of southern China, was investigated based on living observation, protargol staining, and molecular analyses. The new genus Pseudolitonotus gen. n. is characterized by the last left somatic kinety (LKn) being shortened and none of the right somatic kineties extending to the anterior end of the cell, thus distinguishing it from all known pleurostomatid genera. The type species, Pseudolitonotus spirelis sp. n., is characterized by the possession of two macronuclear nodules, 11–15 right and 7–9 left kineties, a single contractile vacuole subterminally located, extrusomes evenly spaced along the entire ventral margin and some forming an “apical group”, two types of cortical granules, and the bottom of the oral slit invariably being twisted. Litonotus gracilis (Pan et al. Eur J Protistol 51:494–506, 2015) is believed to be another member of this new genus as its LKn and right somatic kineties are all shortened. Hence, a new combination, Pseudolitonotus gracilis (Pan et al., 2015) comb. n., is suggested and its diagnosis is improved. Molecular phylogenetic analyses based on SSU rDNA sequence data reveal that Pseudolitonotus gen. n. is monophyletic and groups with Apolitonotus (Pan et al. J Eukaryot Microbiol 67:252–262, 2020) of the family Protolitonotidae (Wu et al. Zool Scr 46:245–253, 2017). However, the familial assignment of this new genus is uncertain based on current data.
基金supported by the Foundation and Applied Basic Research Fund Project of Guangdong Province(2019A1515110606)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai).
文摘Xanthophyll has multiple physiological functions to improve the quality of farmed animals.The present study aimed to investigate the effects of xanthophyll on the growth performance,antioxidation,immunity,pigmentation and meat quality of southern catfish(Silurus soldatovi meridionalis Chen).Juvenile southern catfish(18.35±0.04 g)were randomly allocated into 24 cages(30 juveniles per cage),and fed diets with different dietary xanthophyll levels(at 14,42,80,108,126 and 152 mg/kg,dry matter of diet)twice daily for 8 weeks.Results indicated that the diet with 80 mg/kg xanthophyll induced a higher specific growth rate(SGR),feed efficiency ratio and protein productive value.Moreover,the 80 mg/kg xanthophyll diet also increased complement 3,immunoglobulin M(IgM)and lysozyme content more than the other groups.The mRNA expression level of inflammation-related genes and antioxidant enzyme activities further confirmed the effects of 80 mg/kg dietary xanthophyll on improving immune response.The present study also found that the 126 mg/kg xanthophyll diet significantly enhanced the content of total carotenoids and xanthophyll,hydroxyproline,collagen and amino acid in muscle.The diet with 126 mg/kg xanthophylls also induced lower drip loss,thawing loss,centrifugal loss,cooking loss and higher muscle adhesiveness,cohesiveness,springiness,gumminess and chewiness than the other treatments.In conclusion,quadratic regression model analysis based on SGR and IgM revealed that the optimum xanthophyll level in the diet was 86.78 and 84.63 mg/kg,respectively.Moreover,broken line regression analysis based on xanthophyll content in dorsal skin and chewiness in muscle demonstrated that the optimal xanthophyll level was between 89.73 and 108.66 mg/kg in the diet of southern catfish(S.soldatovi meridionalis Chen).
基金supported by the National Natural Science Foundation of China(Grant Number 32070406)Guangdong Basic and Applied Basic Research Foundation(Grant Number 2022A1515010773)the Science and Technology Planning Project of Guangzhou(Grant Number 202102080168).
文摘Adaptations of ciliates to hypoxic environments have arisen independently several times.Studies on mitochondrion-related organelle(MRO)metabolisms from distinct anaerobic ciliate groups provide evidence for understanding the transitions from mitochondria to MROs within eukaryotes.To deepen our knowledge about the evolutionary patterns of ciliate anaerobiosis,mass-culture and single-cell transcriptomes of two anaerobic species,Metopus laminarius(class Armophorea)and Plagiopyla cf.narasimhamurtii(class Plagiopylea),were sequenced and their MRO metabolic maps were compared.In addition,we carried out comparisons using publicly available predicted MRO proteomes from other ciliate classes(i.e.,Armophorea,Litostomatea,Muranotrichea,Oligohymenophorea,Parablepharismea and Plagiopylea).We found that single-cell transcriptomes were similarly comparable to their mass-culture counterparts in predicting MRO metabolic pathways of ciliates.The patterns of the components of the MRO metabolic pathways might be divergent among anaerobic ciliates,even among closely related species.Notably,our findings indicate the existence of group-specific functional relics of electron transport chains(ETCs).Detailed group-specific ETC functional patterns are as follows:full oxidative phosphorylation in Oligohymenophorea and Muranotrichea;only electron-transfer machinery in Armophorea;either of these functional types in Parablepharismea;and ETC functional absence in Litostomatea and Plagiopylea.These findings suggest that adaptation of ciliates to anaerobic conditions is group-specific and has occurred multiple times.Our results also show the potential and the limitations of detecting ciliate MRO proteins using single-cell transcriptomes and improve the understanding of the multiple transitions from mitochondria to MROs within ciliates.
基金supported by the National Natural Science Foundation of China(project nos.32030015,32170533,31961123002,32111530116)the China Postdoctoral Science Foundation(project no.2021M701276)+1 种基金the Slovak Research and Development Agency(project no.APVV-19-0076)the King Saud University,Saudi Arabia(project no.RSP2022R7).
文摘The morphology and molecular phylogeny of freshwater pleurostomatid ciliates are insufficiently explored.In the present study,we investigated three new Amphileptus species discovered in Lake Weishan and its vicinity,northern China,using standard alpha-taxonomic methods.Amphileptus paracarchesi sp.nov.is characterized by a lateral fossa(groove)in the posterior body portion,four macronuclear nodules,contractile vacuoles distributed along the dorsal margin,and 4-6 left and 44-50 right somatic kineties.Amphileptus pilosus sp.nov.differs from congeners by having 4-14 macronuclear nodules,numerous contractile vacuoles scattered throughout the cytoplasm,and 22-31 left and 35-42 right somatic kineties.Amphileptus orientalis sp.nov.is characterized by two ellipsoidal macronuclear nodules,three ventral contractile vacuoles,and about four left and 31-35 right somatic kineties.Phylogenetic analyses of nuclear small subunit ribosomal DNA(SSU rDNA)sequences indicate that the family Amphileptidae might be monophyletic while the genus Amphileptus is paraphyletic,as Pseudoamphileptus macrostoma robustly groups with Amphileptus sp.Although deep phylogenetic relationships of amphileptids are poorly resolved,multiple well-delimited species groups are recognizable within the genus Amphileptus.
基金supported by the National Natural Science Foundation ofChina (32171493)Guangdong Provincial Key Laboratory of Functional Substances in Medicinal Edible Resources and Healthcare Products (2021B1212040015)Doctor Initiating Project of the Hanshan Normal University (QD202235,QD202236).
