Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum p...Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.展开更多
The spinosaurids represent an enigmatic and highly unusual form of large tetanuran theropods that were first identified in 1915. A recent flurry of discoveries and taxonomic revisions of this important and interesting...The spinosaurids represent an enigmatic and highly unusual form of large tetanuran theropods that were first identified in 1915. A recent flurry of discoveries and taxonomic revisions of this important and interesting clade has added greatly to our knowledge. Spinosaur body fossils are however generally rare and most species are known from only limited skeletal remains. Their unusual anatomical adaptations to the skull, limbs and axial column all differ from other large theropods and point to an unusual ecological niche and a lifestyle intimately linked to water.展开更多
The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains...The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains and few have been described in detail,and as a result,much of their biology remains uncertain.This is despite their importance as potentially one of the earliest branches of pterosaur evolution or even lying close to the origins of pterodactyloids.This review covers the taxonomy and palaeoecology of the anurognathids,which remain an interesting branch of pterosaurian evolution.展开更多
Objective:To identify the prevalence of Acanthamoeba in drinking water treatment plants during the course of the purification processes.Methods:Samples were taken from two drinking water purification plants and monito...Objective:To identify the prevalence of Acanthamoeba in drinking water treatment plants during the course of the purification processes.Methods:Samples were taken from two drinking water purification plants and monitored for the presence of Acanthamoeba in order to estimate the removal capacity of treatment methods employed. Water samples were collected at each step in the purification,during the one year survey,and analysed for the presence of Acanthamoeba spp.by plating on bacterial-seeded plates.Results:The results showed that amoebae were present in surface raw waters in 100%of the samples tested.Acanthamoeba spp.were isolated from 71%and 57%of the water samples collected from post flat-bottom clarifier 1 and post-sedimentation plant respectively.Considering the outflow drinking waters,the removal capacity was 100%in both purification plants monitored.The occurrence of Acanthamoeba was not associated with seasonality.Conclusion: These findings confirm that water purification plants employing methods of flocculation,sedimentation,and filtration in combination with activated charcoal filtration,ozonisation and chlorination exhibited sufficient Acanthamoeba removal capacity and the presence of amoebae in the tap water may be due to older plumbing,water storage tanks,tap water hygiene,and/or environmental settings.展开更多
The understanding of what habitat means for an organism as well as the underlying factors driving patterns of habitat use is still unknown for many species. Cetacean habitat has been described using a range of methodo...The understanding of what habitat means for an organism as well as the underlying factors driving patterns of habitat use is still unknown for many species. Cetacean habitat has been described using a range of methodologies and variables measured over various temporal and spatial scales?that are often author-dependent. However, in order to develop an objective and sound understanding of what habitat actually means for cetaceans, a standardized approach needs to be developed. Here, after briefly reviewing the fundamental differences between terrestrial and marine habitats, we highlight the difficulty in defining a marine habitat, with a special focus on marine mammals. We subsequently provide six recommendations by which future cetacean habitat studies might be approached. This recommended approach aims to amend the way in which we think about and undertake investigations into cetacean habitat. It is believed that through this broadened approach, future cetacean habitat studies will increase our understanding of underlying driving factors of cetacean habitat, rather than just describing distribution patterns. Finally, it is stressed how the proposed approach will be more directly applicable within management frameworks and of benefit to conservation initiatives.展开更多
In the years since the first description of a pterosaur specimen in 1784, pterosaur research has inevitably advanced considerably. However the last decade has arguably seen a much greater increase in our knowledge tha...In the years since the first description of a pterosaur specimen in 1784, pterosaur research has inevitably advanced considerably. However the last decade has arguably seen a much greater increase in our knowledge than the preceding two centuries. Since the turn of the new millennium, more than 40 new pterosaur genera and species have been described and whole new clades have been discovered, in addition to much new data being developed on pterosaur anatomy, functional morphology, palaeobiology, systematics, ecology and more. We are perhaps at the start of a golden age of pterosaur research and much as the dinosaurs underwent a revolution in the 1970s through to the early 1990s, now the Pterosauria are taking their turn. There is also a new and wider interest in pterosaur work as it attracts both more researchers and greater public interest. Pterosaurs appear to be an increasingly popular aspect of paleontology in popular culture and of interest to the media, both mainstream and digital.展开更多
Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance.Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorl...Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance.Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorly understood.Here,we hypothesize that the coordination and trade-offs between floral hydraulics and economics traits are independent of environmental conditions.To test this hypothesis,we investigated a total of 27 flower economics and hydraulic traits in six aquatic and six terrestrial herbaceous species grown in a tropical botanical garden.We found that although there were a few significant differences,most flower hydraulics and economics traits did not differ significantly between aquatic and terrestrial herbaceous plants.Both flower mass per area and floral longevity were significantly positively correlated with the time required for drying full-hydrated flowers to 70%relative water content.Flower dry matter content was strongly and positively related to drought tolerance of the flowers as indicated by flower water potential at the turgor loss point.In addition,there was a trade-off between hydraulic efficiency and the construction cost of a flower across species.Our results show that flowers of aquatic and terrestrial plants follow the same economics spectrum pattern.These results suggest a convergent flower economics design across terrestrial and aquatic plants,providing new insights into the mechanisms by which floral organs adapt to aquatic and terrestrial habitats.展开更多
The cryptic habits of subterranean termites restricts detailed analysis of their foraging patterns in situ, but the process is evidently dominated by tunnel constructions connecting the nest with woody resources disco...The cryptic habits of subterranean termites restricts detailed analysis of their foraging patterns in situ, but the process is evidently dominated by tunnel constructions connecting the nest with woody resources discovered within the territory of each colony. In this study, tunnel formation and orientation were studied experimentally in the termite Reticulitermes grassei （Clement）, using 2-dimensional laboratory foraging arenas con- taining fine sand as the substratum. The building of exploratory tunnels over a 10-day period and the geometry of the resulting network are described. Fractal analysis showed that tunnel geometry had a fractal dimension, regardless of the total length tunnelled whether foragers encountered the food source or not. The bulk density of the sand in the arenas affected the distances tunnelled, with higher density reducing construction, but did not affect tunnel geometry. Tunnels were not discernibly orientated with respect to the positioning of the food source, even in a situation where termites had failed to find the food source at a distance of less than 50 mm, suggesting that volatiles from wood are not attractants.展开更多
The structural dynamics and flexibility of cell membranes play fundamental roles in the functions of the cells, i.e., signaling, energy transduction, and physiological adaptation. The cyanobacterial thylakoid membrane...The structural dynamics and flexibility of cell membranes play fundamental roles in the functions of the cells, i.e., signaling, energy transduction, and physiological adaptation. The cyanobacterial thylakoid membrane represents a model membrane that can conduct both oxygenic photosynthesis and respiration simultaneously. In this study, we conducted direct visualization of the global organization and mobility of photosynthetic complexes in thylakoid membranes from a model cyanobacterium, Synechococcus elongatus PCC 7942, using high-resolution atomic force, confocal, and total internal reflection fluorescence microscopy. We visualized the native arrangement and dense packing of photosystem I （PSI）, photosystem II （PSlI）, and cytochrome （Cyt） befwithin thylakoid membranes at the molecular level. Furthermore, we func- tionally tagged PSI, PSlI, Cyt bef, and ATP synthase individually with fluorescent proteins, and revealed the heterogeneous distribution of these four photosynthetic complexes and determined their dynamic features within the crowding membrane environment using live-cell fluorescence imaging. We characterized red light-induced clustering localization and adjustable diffusion of photosynthetic complexes in thylakoid membranes, representative of the reorganization of photosynthetic apparatus in response to environmental changes. Understanding the organization and dynamics of photosynthetic membranes is essential for rational design and construction of artificial photosynthetic systems to undarpin bioenergy development. Knowledge of cyanobacterial thylakoid membranes could also be extended to other cell membranes, such as chloroplast and mitochondrial membranes.展开更多
We report the synthesis, characterisation and catalytic performance of two nature-inspired biomassderived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of...We report the synthesis, characterisation and catalytic performance of two nature-inspired biomassderived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of a real food waste（lobster shells） or by mimicking the composition of lobster shells using chitin and CaCO3 particles followed by acid washing. The simplified model of artificial lobster was prepared for better reproducibility. The calcium carbonate in both samples acts as a pore agent, creating increased surface area and pore volume, though considerably higher in artificial lobster samples due to the better homogeneity of the components. Various characterisation techniques revealed the presence of a considerable amount of hydroxyapatite left in the real lobster samples after acid washing and a low content of carbon（23%）, nitrogen and sulphur（〈1%）, limiting the surface area to 23 m^2/g, and consequently resulting in rather poor catalytic activity. However, artificial lobster samples, with a surface area of ≈200 m^2/g and a nitrogen doping of 2%, showed a promising onset potential, very similar to a commercially available platinum catalyst, with better methanol tolerance, though with lower stability in long time testing over 10,000 s.展开更多
Observations that rates of introgression between taxa can vary across loci are increasingly common. Here, we test for differential locus-wise introgression in 2 parapatric subspecies of Pearson＇s horseshoe bat （Rhin...Observations that rates of introgression between taxa can vary across loci are increasingly common. Here, we test for differential locus-wise introgression in 2 parapatric subspecies of Pearson＇s horseshoe bat （Rhinolophus pearsoni chinensis and R. p. pearsoni）. To efficiently identify putative speciation genes and/or beneficial genes in our current system, we used a candidate gene approach by including loci from X chromosome that are suggested to be more likely involved in reproductive isolation in other organisms and loci underlying hearing that have been suggested to spread across the hybrid zone in another congeneric species. Phylogenetic and coalescent analyses were performed at 2 X-linked, 4 hearing genes, as well as 2 other autosomal loci individually. Likelihood ratio tests could not reject the model of zero gene flow at 2 X-linked and 2 autosomal genes. In contrast, gene flow was supported at 3 of 4 hearing genes. While this introgression could be adaptive, we cannot rule out stochastic processes. Our results highlight the utility of the candidate gene approach in searching for speciation genes and/or beneficial genes across the species boundary in natural populations.展开更多
We describe the formation of the major axon pathways in the embryonic central and peripheral nervous systems of the amphipod crustacean Orchestia cavimana Heller,1865 by means of antibody staining against acetylated a...We describe the formation of the major axon pathways in the embryonic central and peripheral nervous systems of the amphipod crustacean Orchestia cavimana Heller,1865 by means of antibody staining against acetylated alphatubulin.The data add to a long list of previous studies of various other aspects of development in Orchestia and provide a basis for future studies of neurogenesis on a deeper cellular and molecular level.Orchestia exhibits a tripartite dorsal brain,which is a characteristic feature of euarthropods.Its anlagen are the first detectable structures in the developing nervous system and can be traced back to distinct neuronal cell clusters in the early embryo.The development of the ventral nervous system proceeds with an anteroposterior gradient of development.In each trunk segment,the longitudinal connectives and the anterior commissure form first,followed by the intersegmental nerve,the posterior commissure and segmental nerves,respectively.A single commissure of a vestigial seventh pleonal segment is found.In the peripheral nervous system we observe a spatial and temporal pattern of leg innervation,which is strikingly similar in both limb types,the uniramous pereopods and the biramous pleopods.A proximal leg nerve splitting distally into two separated nerves probably reflects a general feature of crustaceans.展开更多
The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied th...The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied through high-level ab-initio calculations.The geometries optimization and vibrational frequencies calculation for all the reactants,transition states,and products were obtained at the M06-2X/6-311ttG(d,p)level of theory.The zeropoint energy(ZPE)corrected potential energy surfaces(PESs)were determined at the QCISD(T)/cc-pVDZ,TZ level of theory with basis set corrections from MP2/cc-pVDZ,TZ,QZ methods for single point energy calculations.Conventional transition state theory(TST)was used for the rate constants calculations of H-atom abstraction reactions by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2))at temperatures from 298.15 to 2000 K,while the a-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory(VTST).The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures.Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K.Rice-Ramsperger-Kassel-Marcus/Master Equation(RRKM/ME)has been used to calculate the pressure-and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300-2000 K and pressures of 0.01-100 atm.A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals.All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.展开更多
Whereas a rich literature exists for estimating population genetic divergence, metrics of phenotypic trait divergence are lacking, particularly for comparing multiple traits among three or more populations. Here, we r...Whereas a rich literature exists for estimating population genetic divergence, metrics of phenotypic trait divergence are lacking, particularly for comparing multiple traits among three or more populations. Here, we review and analyze via simula- tion Hedges＇ g, a widely used parametric estimate of effect size. Our analyses indicate that g is sensitive to a combination of unequal trait variances and unequal sample sizes among populations and to changes in the scale of measurement. We then go on to derive and explain a new, non-parametric distance measure, ＇Aft＇, which is caiculated based upon a joint cumulative distribution function （CDF） from all populations under study. More precisely, distances are measured in terms of the percentiles in this CDF at which each population＇s median lies. Ap combines many desirable features of other distance metrics into a single metric; namely, compared to other metrics, p is relatively insensitive to unequal variances and sample sizes among the populations sam- pied. Furthermore, a key feature of Ap--and our main motivation for developing it--is that it easily accommodates simultaneous comparisons of any number of traits across any number of populations. To exemplify its utility, we employ Ap to address a ques- tion related to the role of sexual selection in speciation： are sexual signals more divergent than ecological traits in closely related taxa？ Using traits of known function in closely related populations, we show that traits predictive of reproductive performance are indeed, more divergent and more sexually dimorphic than traits related to ecological adaptation [Current Zoology 58 （3）： 426-439 2012].展开更多
The retention of dense and well-functioning microbial biomass is crucial for effective pollutant removal in several biological wastewater treatment technologies.High solids retention is often achieved through aggregat...The retention of dense and well-functioning microbial biomass is crucial for effective pollutant removal in several biological wastewater treatment technologies.High solids retention is often achieved through aggregation of microbial communities into dense,spherical aggregates known as granules,which were initially discovered in the 1980s.These granules have since been widely applied in upflow anaerobic digesters for waste-to-energy conversions.Furthermore,granular biomass has been applied in aerobic wastewater treatment and anaerobic ammonium oxidation(anammox)technologies.The mechanisms underpinning the formation of methanogenic,aerobic,and anammox granules are the subject of ongoing research.Although each granule type has been extensively studied in isolation,there has been a lack of comparative studies among these granulation processes.It is likely that there are some unifying concepts that are shared by all three sludge types.Identifying these unifying concepts could allow a unified theory of granulation to be formed.Here,we review the granulation mechanisms of methanogenic,aerobic,and anammox granular sludge,highlighting several common concepts,such as the role of extracellular polymeric substances,cations,and operational parameters like upflow velocity and shear force.We have then identified some unique features of each granule type,such as different internal structures,microbial compositions,and quorum sensing systems.Finally,we propose that future research should prioritize aspects of microbial ecology,such as community assembly or interspecies interactions in individual granules during their formation and growth.展开更多
基金supported by the National Natural Science Foundation of China(Nos:32071735,32371576,32350410420,41861144016,and 31570406)CAS‘Light of West China’Program+2 种基金The 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences(E3ZKFF1K,E3ZKFF2B)Yunnan Provincial Science and Technology Department(2018HB068)Yunnan Revitalization Talents Support Plan(YNWR-QNBJ-2019177).
文摘Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.
文摘The spinosaurids represent an enigmatic and highly unusual form of large tetanuran theropods that were first identified in 1915. A recent flurry of discoveries and taxonomic revisions of this important and interesting clade has added greatly to our knowledge. Spinosaur body fossils are however generally rare and most species are known from only limited skeletal remains. Their unusual anatomical adaptations to the skull, limbs and axial column all differ from other large theropods and point to an unusual ecological niche and a lifestyle intimately linked to water.
文摘The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains and few have been described in detail,and as a result,much of their biology remains uncertain.This is despite their importance as potentially one of the earliest branches of pterosaur evolution or even lying close to the origins of pterodactyloids.This review covers the taxonomy and palaeoecology of the anurognathids,which remain an interesting branch of pterosaurian evolution.
基金support provided by Three Valleys Water,UKVeolia Water, UK.funded by the Life Sciences Research Grant,University of London
文摘Objective:To identify the prevalence of Acanthamoeba in drinking water treatment plants during the course of the purification processes.Methods:Samples were taken from two drinking water purification plants and monitored for the presence of Acanthamoeba in order to estimate the removal capacity of treatment methods employed. Water samples were collected at each step in the purification,during the one year survey,and analysed for the presence of Acanthamoeba spp.by plating on bacterial-seeded plates.Results:The results showed that amoebae were present in surface raw waters in 100%of the samples tested.Acanthamoeba spp.were isolated from 71%and 57%of the water samples collected from post flat-bottom clarifier 1 and post-sedimentation plant respectively.Considering the outflow drinking waters,the removal capacity was 100%in both purification plants monitored.The occurrence of Acanthamoeba was not associated with seasonality.Conclusion: These findings confirm that water purification plants employing methods of flocculation,sedimentation,and filtration in combination with activated charcoal filtration,ozonisation and chlorination exhibited sufficient Acanthamoeba removal capacity and the presence of amoebae in the tap water may be due to older plumbing,water storage tanks,tap water hygiene,and/or environmental settings.
文摘The understanding of what habitat means for an organism as well as the underlying factors driving patterns of habitat use is still unknown for many species. Cetacean habitat has been described using a range of methodologies and variables measured over various temporal and spatial scales?that are often author-dependent. However, in order to develop an objective and sound understanding of what habitat actually means for cetaceans, a standardized approach needs to be developed. Here, after briefly reviewing the fundamental differences between terrestrial and marine habitats, we highlight the difficulty in defining a marine habitat, with a special focus on marine mammals. We subsequently provide six recommendations by which future cetacean habitat studies might be approached. This recommended approach aims to amend the way in which we think about and undertake investigations into cetacean habitat. It is believed that through this broadened approach, future cetacean habitat studies will increase our understanding of underlying driving factors of cetacean habitat, rather than just describing distribution patterns. Finally, it is stressed how the proposed approach will be more directly applicable within management frameworks and of benefit to conservation initiatives.
文摘In the years since the first description of a pterosaur specimen in 1784, pterosaur research has inevitably advanced considerably. However the last decade has arguably seen a much greater increase in our knowledge than the preceding two centuries. Since the turn of the new millennium, more than 40 new pterosaur genera and species have been described and whole new clades have been discovered, in addition to much new data being developed on pterosaur anatomy, functional morphology, palaeobiology, systematics, ecology and more. We are perhaps at the start of a golden age of pterosaur research and much as the dinosaurs underwent a revolution in the 1970s through to the early 1990s, now the Pterosauria are taking their turn. There is also a new and wider interest in pterosaur work as it attracts both more researchers and greater public interest. Pterosaurs appear to be an increasingly popular aspect of paleontology in popular culture and of interest to the media, both mainstream and digital.
基金supported by the National Natural Science Foundation of China(32171507,31870385,31901285)CAS"Light of West China"program。
文摘Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance.Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorly understood.Here,we hypothesize that the coordination and trade-offs between floral hydraulics and economics traits are independent of environmental conditions.To test this hypothesis,we investigated a total of 27 flower economics and hydraulic traits in six aquatic and six terrestrial herbaceous species grown in a tropical botanical garden.We found that although there were a few significant differences,most flower hydraulics and economics traits did not differ significantly between aquatic and terrestrial herbaceous plants.Both flower mass per area and floral longevity were significantly positively correlated with the time required for drying full-hydrated flowers to 70%relative water content.Flower dry matter content was strongly and positively related to drought tolerance of the flowers as indicated by flower water potential at the turgor loss point.In addition,there was a trade-off between hydraulic efficiency and the construction cost of a flower across species.Our results show that flowers of aquatic and terrestrial plants follow the same economics spectrum pattern.These results suggest a convergent flower economics design across terrestrial and aquatic plants,providing new insights into the mechanisms by which floral organs adapt to aquatic and terrestrial habitats.
文摘The cryptic habits of subterranean termites restricts detailed analysis of their foraging patterns in situ, but the process is evidently dominated by tunnel constructions connecting the nest with woody resources discovered within the territory of each colony. In this study, tunnel formation and orientation were studied experimentally in the termite Reticulitermes grassei （Clement）, using 2-dimensional laboratory foraging arenas con- taining fine sand as the substratum. The building of exploratory tunnels over a 10-day period and the geometry of the resulting network are described. Fractal analysis showed that tunnel geometry had a fractal dimension, regardless of the total length tunnelled whether foragers encountered the food source or not. The bulk density of the sand in the arenas affected the distances tunnelled, with higher density reducing construction, but did not affect tunnel geometry. Tunnels were not discernibly orientated with respect to the positioning of the food source, even in a situation where termites had failed to find the food source at a distance of less than 50 mm, suggesting that volatiles from wood are not attractants.
文摘The structural dynamics and flexibility of cell membranes play fundamental roles in the functions of the cells, i.e., signaling, energy transduction, and physiological adaptation. The cyanobacterial thylakoid membrane represents a model membrane that can conduct both oxygenic photosynthesis and respiration simultaneously. In this study, we conducted direct visualization of the global organization and mobility of photosynthetic complexes in thylakoid membranes from a model cyanobacterium, Synechococcus elongatus PCC 7942, using high-resolution atomic force, confocal, and total internal reflection fluorescence microscopy. We visualized the native arrangement and dense packing of photosystem I （PSI）, photosystem II （PSlI）, and cytochrome （Cyt） befwithin thylakoid membranes at the molecular level. Furthermore, we func- tionally tagged PSI, PSlI, Cyt bef, and ATP synthase individually with fluorescent proteins, and revealed the heterogeneous distribution of these four photosynthetic complexes and determined their dynamic features within the crowding membrane environment using live-cell fluorescence imaging. We characterized red light-induced clustering localization and adjustable diffusion of photosynthetic complexes in thylakoid membranes, representative of the reorganization of photosynthetic apparatus in response to environmental changes. Understanding the organization and dynamics of photosynthetic membranes is essential for rational design and construction of artificial photosynthetic systems to undarpin bioenergy development. Knowledge of cyanobacterial thylakoid membranes could also be extended to other cell membranes, such as chloroplast and mitochondrial membranes.
基金the EU for the Intra European Marie Curie Research Fellowship (PIEFGA-2013-623227)
文摘We report the synthesis, characterisation and catalytic performance of two nature-inspired biomassderived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of a real food waste（lobster shells） or by mimicking the composition of lobster shells using chitin and CaCO3 particles followed by acid washing. The simplified model of artificial lobster was prepared for better reproducibility. The calcium carbonate in both samples acts as a pore agent, creating increased surface area and pore volume, though considerably higher in artificial lobster samples due to the better homogeneity of the components. Various characterisation techniques revealed the presence of a considerable amount of hydroxyapatite left in the real lobster samples after acid washing and a low content of carbon（23%）, nitrogen and sulphur（〈1%）, limiting the surface area to 23 m^2/g, and consequently resulting in rather poor catalytic activity. However, artificial lobster samples, with a surface area of ≈200 m^2/g and a nitrogen doping of 2%, showed a promising onset potential, very similar to a commercially available platinum catalyst, with better methanol tolerance, though with lower stability in long time testing over 10,000 s.
文摘Observations that rates of introgression between taxa can vary across loci are increasingly common. Here, we test for differential locus-wise introgression in 2 parapatric subspecies of Pearson＇s horseshoe bat （Rhinolophus pearsoni chinensis and R. p. pearsoni）. To efficiently identify putative speciation genes and/or beneficial genes in our current system, we used a candidate gene approach by including loci from X chromosome that are suggested to be more likely involved in reproductive isolation in other organisms and loci underlying hearing that have been suggested to spread across the hybrid zone in another congeneric species. Phylogenetic and coalescent analyses were performed at 2 X-linked, 4 hearing genes, as well as 2 other autosomal loci individually. Likelihood ratio tests could not reject the model of zero gene flow at 2 X-linked and 2 autosomal genes. In contrast, gene flow was supported at 3 of 4 hearing genes. While this introgression could be adaptive, we cannot rule out stochastic processes. Our results highlight the utility of the candidate gene approach in searching for speciation genes and/or beneficial genes across the species boundary in natural populations.
基金We thank the plant physiology section at Humboldt University,Berlin for help with the CLSM.We are very grateful to Caterina Biffis,Georg Brenneis and the 2 anonymous reviewers for the helpful advice.We also thank Stephen Rossiter for improving the English.
文摘We describe the formation of the major axon pathways in the embryonic central and peripheral nervous systems of the amphipod crustacean Orchestia cavimana Heller,1865 by means of antibody staining against acetylated alphatubulin.The data add to a long list of previous studies of various other aspects of development in Orchestia and provide a basis for future studies of neurogenesis on a deeper cellular and molecular level.Orchestia exhibits a tripartite dorsal brain,which is a characteristic feature of euarthropods.Its anlagen are the first detectable structures in the developing nervous system and can be traced back to distinct neuronal cell clusters in the early embryo.The development of the ventral nervous system proceeds with an anteroposterior gradient of development.In each trunk segment,the longitudinal connectives and the anterior commissure form first,followed by the intersegmental nerve,the posterior commissure and segmental nerves,respectively.A single commissure of a vestigial seventh pleonal segment is found.In the peripheral nervous system we observe a spatial and temporal pattern of leg innervation,which is strikingly similar in both limb types,the uniramous pereopods and the biramous pleopods.A proximal leg nerve splitting distally into two separated nerves probably reflects a general feature of crustaceans.
基金supported by the National Science and Technology Major Project(2017-Ⅲ-0004-0028/J2019-Ⅲ-0005-0048)NSFC(51976216)+1 种基金Sinopec Science and Technology Departmentthe High-Performance Computing(HPC)Center of Beihang University.
文摘The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied through high-level ab-initio calculations.The geometries optimization and vibrational frequencies calculation for all the reactants,transition states,and products were obtained at the M06-2X/6-311ttG(d,p)level of theory.The zeropoint energy(ZPE)corrected potential energy surfaces(PESs)were determined at the QCISD(T)/cc-pVDZ,TZ level of theory with basis set corrections from MP2/cc-pVDZ,TZ,QZ methods for single point energy calculations.Conventional transition state theory(TST)was used for the rate constants calculations of H-atom abstraction reactions by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2))at temperatures from 298.15 to 2000 K,while the a-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory(VTST).The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures.Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K.Rice-Ramsperger-Kassel-Marcus/Master Equation(RRKM/ME)has been used to calculate the pressure-and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300-2000 K and pressures of 0.01-100 atm.A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals.All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.
基金Acknowlegements We thank Matthew Arnegard, Carlos Botero, Tamra Mendelson, Rafael Rodriqu6z and Sander van Doom for excellent discussions about the need for a new phenotypic distance metric and Maria Servedio for the invitation and encouragement to formalize our ideas. This research was supported as part of the Sexual Selection and Speciation working group by the National Evolutionary Synthesis Center （NESCent）, NSF #EF-0905606. RJS and SMF were supported by the University of Colorado and National Science Founda- tion grant IOS-0717421to RJS. MK was supported by a grant from the Vienna Science and Technology Fund （WWTF） to the Mathematics and Biosciences Group at the University of Vienna. EAH thanks Mitch Bern for use of his Master＇s thesis data and was supported by the National Science Foundation grant lOS - 0643179. DEI and DPLT were supported by the Natural Sciences and Engineering Research Council of Can- ada （Discovery Grants 311931-2005 and 311931-2010 to DEI, CGS-D to DPLT）. NS and JAT were supported by the Royal Society, British Ecological Society and John Fell Fund （Ox- ford University）. ES supported by NSF-DDIG the American Ornithologists Union, the University of Chicago, and the American Philosophical Society Lewis and Clark award. JACU was funded by National Science Foundation grant lOS 0306175.
文摘Whereas a rich literature exists for estimating population genetic divergence, metrics of phenotypic trait divergence are lacking, particularly for comparing multiple traits among three or more populations. Here, we review and analyze via simula- tion Hedges＇ g, a widely used parametric estimate of effect size. Our analyses indicate that g is sensitive to a combination of unequal trait variances and unequal sample sizes among populations and to changes in the scale of measurement. We then go on to derive and explain a new, non-parametric distance measure, ＇Aft＇, which is caiculated based upon a joint cumulative distribution function （CDF） from all populations under study. More precisely, distances are measured in terms of the percentiles in this CDF at which each population＇s median lies. Ap combines many desirable features of other distance metrics into a single metric; namely, compared to other metrics, p is relatively insensitive to unequal variances and sample sizes among the populations sam- pied. Furthermore, a key feature of Ap--and our main motivation for developing it--is that it easily accommodates simultaneous comparisons of any number of traits across any number of populations. To exemplify its utility, we employ Ap to address a ques- tion related to the role of sexual selection in speciation： are sexual signals more divergent than ecological traits in closely related taxa？ Using traits of known function in closely related populations, we show that traits predictive of reproductive performance are indeed, more divergent and more sexually dimorphic than traits related to ecological adaptation [Current Zoology 58 （3）： 426-439 2012].
基金GC,MP and SM were supported by a European Research Council Starting Grant awarded to GC(3C-BIOTECH 261330)by a Science Foundation Ireland Career Development Award(17/CDA/4658)to GC+1 种基金VOF is supported by the Enterprise Ireland Technology Centres Programme(TC/2014/0016)Science Foundation Ireland(14/IA/2371 and 16/RC/3889).
文摘The retention of dense and well-functioning microbial biomass is crucial for effective pollutant removal in several biological wastewater treatment technologies.High solids retention is often achieved through aggregation of microbial communities into dense,spherical aggregates known as granules,which were initially discovered in the 1980s.These granules have since been widely applied in upflow anaerobic digesters for waste-to-energy conversions.Furthermore,granular biomass has been applied in aerobic wastewater treatment and anaerobic ammonium oxidation(anammox)technologies.The mechanisms underpinning the formation of methanogenic,aerobic,and anammox granules are the subject of ongoing research.Although each granule type has been extensively studied in isolation,there has been a lack of comparative studies among these granulation processes.It is likely that there are some unifying concepts that are shared by all three sludge types.Identifying these unifying concepts could allow a unified theory of granulation to be formed.Here,we review the granulation mechanisms of methanogenic,aerobic,and anammox granular sludge,highlighting several common concepts,such as the role of extracellular polymeric substances,cations,and operational parameters like upflow velocity and shear force.We have then identified some unique features of each granule type,such as different internal structures,microbial compositions,and quorum sensing systems.Finally,we propose that future research should prioritize aspects of microbial ecology,such as community assembly or interspecies interactions in individual granules during their formation and growth.
