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1.
Daisuke Takagi Yuji Suzuki Hiroshi Fukayama Amane Makino Chikahiro Miyake 《Physiologia plantarum》2016,156(2):227-238
This study aims to elucidate the molecular mechanism for the transient increase in the O2‐uptake rate in tobacco (Nicotiana tabacum cv Xanthi) leaves after turning off actinic lights (ALs). The photosynthetic O2 evolution rate reaches a maximum shortly after the onset of illumination with ALs and then decreases to zero in atmospheric CO2/O2 conditions. After turning off the ALs, tobacco leaves show a transient increase in the O2‐uptake rate, the post‐illumination transient O2‐uptake, and thereafter, the O2‐uptake rate decreases to the level of the dark‐respiration rate. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], maintained a steady‐state value distinct from the photosynthetic O2‐evolution rate. In high‐[CO2] conditions, the photosynthetic O2‐evolution rate and Y(II) showed a parallel behavior, and the post‐illumination transient O2‐uptake was suppressed. On the other hand, in maize leaves (a C4 plant), even in atmospheric CO2/O2 conditions, Y(II) paralleled the photosynthetic O2‐evolution rate and the post‐illumination transient O2‐uptake was suppressed. Hypothesizing that the post‐illumination transient O2‐uptake is driven by C3 plant photorespiration in tobacco leaves, we calculated both the ribulose 1,5‐bisphosphate carboxylase‐ and oxygenase‐rates (Vc and Vo) from photosynthetic O2‐evolution and the post‐illumination transient O2‐uptake rates. These values corresponded to those estimated from simultaneous chlorophyll fluorescence/O2‐exchange analysis. Furthermore, the H+‐consumption rate for ATP synthesis in both photosynthesis and photorespiration, calculated from both Vc and Vo that were estimated from chlorophyll fluorescence/CO2‐exchange analysis, showed a positive linear relationship with the dissipation rate of the electrochromic shift signal. Thus, these findings support our hypothesis. 相似文献
2.
PHYLOGEOGRAPHY OF THE TRUMPETFISHES (AULOSTOMUS): RING SPECIES COMPLEX ON A GLOBAL SCALE 总被引:4,自引:0,他引:4
B. W. Bowen A. L. Bass L. A. Rocha W. S. Grant D. R. Robertson 《Evolution; international journal of organic evolution》2001,55(5):1029-1039
Abstract.— The distribution of circumtropical marine species is limited by continental boundaries, cold temperate conditions, and oceanic expanses, but some of these barriers are permeable over evolutionary time scales. Sister taxa that evolved in separate ocean basins can come back into contact, and the consequences of this renewed sympatry may be a key to understanding evolutionary processes in marine organisms. The circumtropical trumpetfishes (Aulostomus) include a West Atlantic species (A. maculatus), an Indian‐Pacific species (A. chinensis), and an East Atlantic species (A. strigosus) that may be the product of a recent invasion from the Indian Ocean. To resolve patterns of divergence and speciation, we surveyed 480 bp of mitochondrial DNA cytochrome b in 196 individuals from 16 locations. Based on a conventional molecular clock of 2% sequence divergence per million years, the deepest partitions in a neighbor‐joining tree (d= 0.063‐0.082) are consistent with separation of West Atlantic and Indian‐Pacific species by the Isthmus of Panama, 3–4 million years ago. By the same criteria, trumpetfish in the East Atlantic were isolated from the Indian Ocean about 2.5 million years ago (d= 0.044‐0.054), coincident with the advent of glacial cycles and cold‐water upwelling around South Africa. Continental barriers between tropical oceans have only rarely been surmounted by trumpetfishes, but oceanic barriers do not appear to be substantial, as indicated by weak population partitioning (øST= 0.093) in A. chinensis across the Indian and Pacific Oceans. Finally, morphological and mitochondrial DNA data indicate hybridization of A. strigosus and A. maculatus in Brazil. After 3–4 million years and a globe‐spanning series of vicariant and dispersal events, trumpetfish lineages have come back into contact in the southwest Atlantic and appear to be merging. This ring species phenomenon may occur in a broad array of marine organisms, with clear implications for the production and maintenance of biodiversity in marine ecosystems. 相似文献
3.
The tuatara (Sphenodon punctatus) is the only living representative of Rhynchocephalia, a group of small vertebrates that originated about 250 million years ago. The tuatara has been referred to as a living fossil; however, the group to which it belongs included a much greater diversity of forms in the Mesozoic. We explore the morphological diversity of Rhynchocephalia and stem lepidosaur relatives (Sphenodon plus 13 fossil relatives) by employing a combination of geometric morphometrics and comparative methods. Geometric morphometrics is used to explore cranium size and shape at interspecific scale, while comparative methods are employed to test association between skull shape and size and tooth number after taking phylogeny into account. Two phylogenetic topologies have been considered to generate a phylomorphospace and quantify the phylogenetic signal in skull shape data, the ancestral state reconstruction as well as morphological disparity using disparity through time plots (DTT). Rhynchocephalia exhibit a significant phylogenetic signal in skull shape that compares well with that computed for other extinct vertebrate groups. A consistent form of allometry has little impact on skull shape evolution while the number of teeth significantly correlates with skull shape also after taking phylogeny into account. The ancestral state reconstruction demonstrates a dramatic shape difference between the skull of Sphenodon and its much larger Cretaceous relative Priosphenodon. Additionally, DTT demonstrates that skull shape disparity is higher between rather than within clades while the opposite applies to skull size and number of teeth. These results were not altered by the use of competing phylogenic hypotheses. Rhynchocephalia evolved as a morphologically diverse group with a dramatic radiation in the Late Triassic and Early Jurassic about 200 million years ago. Differences in size are not marked between species whereas changes in number of teeth are associated with co‐ordinated shape changes in the skull to accommodate larger masticatory muscles. These results show that the tuatara is not the product of evolutionary stasis but that it represents the only survivor of a diverse Mesozoic radiation whose subsequent decline remains to be explained. 相似文献
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Jetty S. S. Ammiraju Chuanzhu Fan Yeisoo Yu Xiang Song Karen A. Cranston Ana Clara Pontaroli Fei Lu Abhijit Sanyal Ning Jiang Teri Rambo Jennifer Currie Kristi Collura Jayson Talag Jeffrey L. Bennetzen Mingsheng Chen Scott Jackson Rod A. Wing 《The Plant journal : for cell and molecular biology》2010,63(3):430-442
Despite knowledge that polyploidy is widespread and a major evolutionary force in flowering plant diversification, detailed comparative molecular studies on polyploidy have been confined to only a few species and families. The genus Oryza is composed of 23 species that are classified into ten distinct ‘genome types’ (six diploid and four polyploid), and is emerging as a powerful new model system to study polyploidy. Here we report the identification, sequence and comprehensive comparative annotation of eight homoeologous genomes from a single orthologous region (Adh1–Adh2) from four allopolyploid species representing each of the known Oryza genome types (BC, CD, HJ and KL). Detailed comparative phylogenomic analyses of these regions within and across species and ploidy levels provided several insights into the spatio‐temporal dynamics of genome organization and evolution of this region in ‘natural’ polyploids of Oryza. The major findings of this study are that: (i) homoeologous genomic regions within the same nucleus experience both independent and parallel evolution, (ii) differential lineage‐specific selection pressures do not occur between polyploids and their diploid progenitors, (iii) there have been no dramatic structural changes relative to the diploid ancestors, (iv) a variation in the molecular evolutionary rate exists between the two genomes in the BC complex species even though the BC and CD polyploid species appear to have arisen <2 million years ago, and (v) there are no clear distinctions in the patterns of genome evolution in the diploid versus polyploid species. 相似文献
7.
José Cerca Christian Meyer Dave Stateczny Dominik Siemon Jana Wegbrod Gunter Purschke Dimitar Dimitrov Torsten H. Struck 《Evolution; international journal of organic evolution》2020,74(1):116-131
Morphological stasis or the absence of morphological change is a well-known phenomenon in the paleontological record, yet it is poorly integrated with neontological evidence. Recent evidence suggests that cryptic species complexes may remain morphologically identical due to morphological stasis. Here, we describe a case of long-term stasis in the Stygocapitella cryptic species complex (Parergodrilidae, Orbiniida, Annelida). Using phylogenetic methods and morphological data, we find that rates of morphological evolution in Stygocapitella are significantly slower than in closely related taxa (Nerillidae, Orbiniidae). Assessment of quantitative and qualitative morphology revealed the presence of four morphotypes with only subtle differences, whereas molecular data supports 10 reproductively isolated clades. Notably, estimates for the time of Stygocapitella species divergence range from ∼275 million years to ∼18 million years, including one case of two morphologically similar species that have diverged about 140 million years ago. These findings provide evidence for morphological deceleration and long-term morphological stasis in Stygocapitella, and that speciation is not necessarily accompanied by morphological changes. The deceleration of morphological divergence in Stygocapitella can be potentially linked to niche conservatism and tracking, coupled with the fluctuating dynamics of the interstitial environment, or genetic constraints due to progenetic evolution. Finally, we conclude that failing to integrate speciation without morphological evolution in paleontology may bias estimates of rates of speciation and morphological evolution. 相似文献
8.
Alena Fornuskova Josef Bryja Michal Vinkler Miloš Macholán Jaroslav Piálek 《Ecology and evolution》2014,4(14):2931-2944
Detailed investigation of variation in genes involved in pathogen recognition is crucial for understanding co‐evolutionary processes between parasites and their hosts. Triggering immediate innate response to invading microbes, Toll‐like receptors (TLRs) belong presently among the best‐studied receptors of vertebrate immunity. TLRs exhibit remarkable interspecific variation and also intraspecific polymorphism is well documented. In humans and laboratory mice, several studies have recently shown that single amino acid substitution may significantly alter receptor function. Unfortunately, data concerning polymorphism in free‐living species are still surprisingly scarce. In this study, we analyzed the polymorphism of Toll‐like receptor 4 (Tlr4) over the Palearctic range of house mouse (Mus musculus). Our results reveal contrasting evolutionary patterns between the two recently (0.5 million years ago) diverged house mouse subspecies: M. m. domesticus (Mmd) and M. m. musculus (Mmm). Comparison with cytochrome b indicates strong directional selection in Mmd Tlr4. Throughout the whole Mmd western Palaearctic region, a single variant of the ligand‐binding region is spread, encoded mainly by one dominant haplotype (71% of Mmd). In contrast, Tlr4 in Mmm is much more polymorphic with several haplotypes at intermediate frequencies. Moreover, we also found clear signals of recombination between two principal haplogroups in Mmm, and we identified eight sites under positive selection in our dataset. Our results suggest that observed differences in Tlr4 diversity may be attributed to contrasting parasite‐mediated selection acting in the two subspecies. 相似文献
9.
MELISSA GREY ZOE V. FINKEL PEIR K. PUFAHL LACEY M. REID 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2012,45(4):615-623
Grey, M., Finkel, Z.V., Pufahl, P.K. & Reid, L.M. 2012: Evolutionary mode of the ostracod, Velatomorpha altilis, at the Joggins Fossil Cliffs UNESCO World Heritage Site. Lethaia, Vol. 45, pp. 615–623. The estuarine ostracod Velatomorpha altilis was analysed for size and shape changes over a 2–3 million‐year interval within a portion of the Joggins Fossil Cliffs World Heritage Site. This represents one of a very few number of studies focused on evolutionary trends within marginal environments and contributes to a growing body of research that attempts to link evolutionary patterns with processes. We measured nearly 400 ostracod specimens and used a quantitative model‐based test to assess mode of evolution. Samples of ostracods were also analysed for their stable oxygen and carbon isotopic compositions in an attempt to supplement paleoenvironmental interpretations. Stasis was the strongly supported model for mode of evolution in both size and shape metrics, lending support to previous hypotheses that organisms from fluctuating, and therefore stressed, environments, should exhibit stasis because they are genetically well adapted to environmental change over geological time‐scales. Stable isotopic compositions indicate samples were diagenetically altered and thus do not preserve a primary signature of paleoenvironmental conditions. Future work should look to other marginal organisms to test whether stasis is indeed a trend in these types of environments. □Carboniferous, estuarine ostracod, environment, evolutionary mode. 相似文献
10.
The eastern Asian (EA)–eastern North American (ENA) floristic disjunction represents a major pattern of phytogeography of the Northern Hemisphere. Despite 20 years of studies dedicated to identification of taxa that display this disjunct pattern, its origin and evolution remain an open question, especially regarding post‐isolation evolution. The blue‐ or white‐fruited dogwoods (BW) are the most species‐rich among the four major clades of Cornus L., consisting of ~35 species divided into three subgenera (subg. Yinquania, subg. Mesomora, and subg. Kraniopsis). The BW group provides an excellent example of the EA–ENA floristic disjunction for biogeographic study due to its diversity distribution centered in eastern Asia and eastern North America, yet its species relationships and delineation have remained poorly understood. In this study, we combined genome‐wide markers from RAD‐seq, morphology, fossils, and climate data to understand species relationships, biogeographic history, and ecological niche and morphological evolution. Our phylogenomic analyses with RAxML and MrBayes recovered a strongly supported and well‐resolved phylogeny of the BW group with three intercontinental disjunct clades in EA and ENA or Eurasia and North America, of which two are newly identified within subg. Kraniopsis. These analyses also recovered a potential new species but failed to resolve relationships within the C. hemsleyi–C. schindleri complex. In an effort to develop an approach to reduce computation time, analysis of different nodal age settings in treePL suggests setting a node's minimum age constraint to the lower bound of a fossil's age range to obtain similar ages to that of BEAST. Divergence time analyses with BEAST and treePL dated the BW stem back to the very Late Cretaceous and the divergence of the three subgenera in the Paleogene. By integrating fossil ages and morphology, a total evidence‐based dating approach was used in conjunction with time‐slice probabilities of dispersal under a DEC model to resolve ancestral ranges of each disjunct in the Miocene: Eurasia and ENA (disjunct 1), EA and western North America (disjunct 2), and EA (disjunct 3). The dated biogeographic history supports dispersal via the North Atlantic Land Bridge in the late Paleogene in disjunct 1 and dispersal via the Bering Land Bridge in the Miocene for disjuncts 2 and 3. Character mapping with a stochastic model in phytools and comparison of ecological niche, morphospace, and rate of evolution indicated differential divergence patterns in morphology, ecological niche, and molecules between disjunct sisters. Although morphological stasis was observed in most of the characters, evolutionary changes in growth habit and some features of leaf, flower, and fruit morphology occurred in one or both sister clades. A significant differentiation of ecological habitats in temperature, precipitation, and elevation between disjunct sisters was observed, suggesting a role of niche divergence in morphological evolution post‐isolation. The patterns of evolutionary rate between morphology and molecules varied among disjunct clades and were not always congruent between morphology and molecules, suggesting cases of non‐neutral morphological evolution driven by ecological selection. Our phylogenetic evidence and comparisons of evolutionary rate among disjunct lineages lend new insights into the formation of the diversity anomaly between EA and ENA, with particular support of an early diversification in EA. These findings, in conjunction with previous studies, again suggest that the EA–ENA disjunct floras are an assembly of lineages descended from the Mesophytic Forests that evolved from the early Paleogene “boreotropical flora” through varied evolutionary pathways across lineages. 相似文献
11.
Thomas Cucchi Ross Barnett Natália Martínková Sabrina Renaud Elodie Renvoisé Allowen Evin Alison Sheridan Ingrid Mainland Caroline Wickham‐Jones Christelle Tougard Jean Pierre Quéré Marine Pascal Gerald Heckel Paul O'Higgins Jeremy B. Searle Keith M. Dobney 《Evolution; international journal of organic evolution》2014,68(10):2804-2820
Island evolution may be expected to involve fast initial morphological divergence followed by stasis. We tested this model using the dental phenotype of modern and ancient common voles (Microtus arvalis), introduced onto the Orkney archipelago (Scotland) from continental Europe some 5000 years ago. First, we investigated phenotypic divergence of Orkney and continental European populations and assessed climatic influences. Second, phenotypic differentiation among Orkney populations was tested against geography, time, and neutral genetic patterns. Finally, we examined evolutionary change along a time series for the Orkney Mainland. Molar gigantism and anterior‐lobe hypertrophy evolved rapidly in Orkney voles following introduction, without any transitional forms detected. Founder events and adaptation appear to explain this initial rapid evolution. Idiosyncrasy in dental features among different island populations of Orkney voles is also likely the result of local founder events following Neolithic translocation around the archipelago. However, against our initial expectations, a second marked phenotypic shift occurred between the 4th and 12th centuries AD, associated with increased pastoral farming and introduction of competitors (mice and rats) and terrestrial predators (foxes and cats). These results indicate that human agency can generate a more complex pattern of morphological evolution than might be expected in island rodents. 相似文献
12.
R. F. Sage 《Plant biology (Stuttgart, Germany)》2001,3(3):202-213
Abstract: C4 photosynthesis is an evolutionary solution to high rates of photorespiration and low kinetic efficiency of Rubisco in CO2‐depleted atmospheres of recent geologic time. About 7500 plant species are C4, in contrast to 30 000 CAM and 250 000 C3 species. All C4 plants occur in approximately 90 genera from 18 angiosperm families. In all of these families, the C4 pathway evolved independently. In many, multiple independent origins have occurred, such that over 30 distinct evolutionary origins of the C4 pathway are recognized. Fossil and carbon isotope evidence show that the C4 syndrome is at least 12 to 15 million years old, although estimates based on molecular sequence comparisons indicate it is over 20 million years old. The evolutionary radiation of herbaceous angiosperms may have been required for C4 plant evolution. All C4 species occur in advanced angiosperm families that appeared in the fossil record in the past 70 million years. Most of these families diversified in terms of genera and species numbers between 20 to 40 million years ago, during a period of global cooling, atmospheric CO2 reduction and aridification. During the period of diversification, numerous traits arose in the C3 flora that enhanced their performance in arid environments and atmospheres of reduced CO2. Some of these traits may have predisposed certain taxa to develop the C4 pathway once atmospheric CO2 levels declined to a point where the ability to concentrate CO2 had a selective advantage. Leading traits in C3 plants that may have facilitated the initial transition to C4 photosynthesis include close vein spacing and an enlargement of the bundle sheath cell layer to form a Kranz‐like anatomy. Ecological factors not directly connected with photosynthesis probably also played a role. For example, extensive ecological disturbance may have been needed to convert C3‐dominated woodlands into open, high‐light habitats where herbaceous C4 plants could succeed. Disturbances in the form of fire, and browsing by large mammals, increase during the time of C4 plant evolution and diversification. Fire increased because of the drying climate, while browsing increased with the evolutionary diversification of the mammalian megafauna in the Oligocene and Miocene epochs. In summary, the origin of C4 plants is hypothesized to have resulted from a novel combination of environmental and phylogenetic developments that, for the first time, established the preconditions required for C4 plant evolution. 相似文献
13.
Giorgio Manzi 《Evolutionary anthropology》2004,13(1):11-24
The cranial morphology of fossil hominids between the end of the Early Pleistocene and the beginning of the Middle Pleistocene provides crucial evidence to understand the distribution in time and space of the genus Homo. This evidence is critical for evaluating the competing models regarding diversity within our genus. The debate focuses on two alternative hypotheses, one basically anagenetic and the other cladogenetic. The first suggests that morphological change is so diffused, slow, and steady that it is meaningless to apply species names to segments of a single lineage. The second is that the morphological variation observed in the fossil record can best be described as a number of distinct species that are not connected in a linear ancestor‐descendant sequence. Today much more fossil evidence is available than was in the past to test these alternative hypotheses, as well as intermediate variants. Special attention must be paid to Africa because this is the most probable continental homeland for both the origin of the genus Homo (around 2.5–2 Ma), 1 as well as the site, two million or so years later, of the emergence of the species H. sapiens. 2 However, the African fossil record is very poorly represented between 1 Ma and 600 ka. Europe furnishes recent discoveries in this time range around the Matuyama‐Brunhes chron boundary (780,000 years ago), a period for which, at present, we have no noteworthy fossil evidence in Africa or the Levant. Two penecontemporaneous sources of European fossil evidence, the Ceprano calvaria (Italy) 3 and the TD6 fossil assemblage of Atapuerca (Spain) 4 are thus of great interest for testing hypotheses about human evolution in the fundamental time span bracketed between the late Early and the Middle Pleistocene. This paper is based on a phenetic approach to cranial variation aimed at reviewing the Early‐to‐Middle Pleistocene trajectories of human evolution. The focus of the paper is on neither the origin nor the end of the story of the genus Homo, but rather its chronological and phylogenetic core. Elucidation of the evolutionary events that happened around 780 ka during the transition from the Early to Middle Pleistocene is one of the new frontiers for human paleontology, and is critical for understanding the processes that ultimately led to the origin of H. sapiens. 相似文献
14.
Priyanka Roy Chowdhury Billy W. Culver John K. Colbourne Lawrence J. Weider Punidan D. Jeyasingh 《Ecology letters》2014,17(3):360-368
For an accurate assessment of the anthropogenic impacts on evolutionary change in natural populations, we need long‐term environmental, genetic and phenotypic data that predate human disturbances. Analysis of c. 1600 years of history chronicled in the sediments of South Center Lake, Minnesota, USA, revealed major environmental changes beginning c. 120 years ago coinciding with the initiation of industrialised agriculture in the catchment area. Population genetic structure, analysed using DNA from dormant eggs of the keystone aquatic herbivore, Daphnia pulicaria, suggested no change for c. 1500 years prior to striking shifts associated with anthropogenic environmental alterations. Furthermore, phenotypic assays on the oldest resurrected metazoan genotypes (potentially as old as c. 700 years) indicate significant shifts in phosphorus utilisation rates compared to younger genotypes. Younger genotypes show steeper reaction norms with high growth under high phosphorus (P), and low growth under low P, while ‘ancient’ genotypes show flat reaction norms, yet higher growth efficiency under low P. Using this resurrection ecology approach, environmental, genetic and phenotypic data spanning pre‐ and post‐industrialised agricultural eras clearly reveal the evolutionary consequences of anthropogenic environmental change. 相似文献
15.
We present an analysis of cranial capacity of 118 hominid crania available from the literature. The crania belong to both
the genusAustralopithecus andHomo and provide a clear outline of hominid cranial evolution starting at more than 3 million years ago. Beginning withA. afarensis there is a clear increase in both absolute and relative brain size with every successive time period.H.s. neandertal has an absolutely and relatively smaller brain size (1412cc, E.Q.=5.6) than fossil modernH.s. sapiens (1487cc, E.Q.=5.9). Three evolutionary models of hominid brain evolution were tested: gradualism, punctuated equilibrium,
and a mixed model using both gradualism and punctuated equilibrium. Both parametric and non-parametric analyses show a clear
trend toward increasing brain size withH. erectus and a possible relationship within archaicH. sapiens. An evolutionary stasis in cranial capacity could not be refuted for all other taxa. Consequently, the mixed model appears
to more fully explain hominid cranial capacity evolution. However, taxonomic decisions could directly compromise the possibility
of testing the evolutionary mechanisms hypothesized to be operating in hominid brain expansion. 相似文献
16.
Micro‐ and Nano‐Structured Vanadium Pentoxide (V2O5) for Electrodes of Lithium‐Ion Batteries
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Vanadium pentoxide (V2O5) has played important roles in lithium‐ion batteries due to its unique crystalline structure. To assist researchers understanding the roles this material plays, a comprehensive and critical review is conducted based on about 250 publications. Here, we report basics and applications of micro‐ and nano‐materials of V2O5 and V2O5‐based composites. The comparative and statistical analysis leads to the discovery of several interesting phenomena. The V2O5 electrodes with two lithium ions have a favorable capacity performance with reversible phase formation. The excellent capacity retention is displayed in the V2O5 electrodes with one lithium ion inserted. In the case of three lithium ions insertion, it was found that the irreversible formation of the phase ω in LixV2O5 leads to its control. In addition, effects of additives on electrode performance, circuitry models of performance, as well as reaction routes are studied. Two unprecedented concepts of the “high capacity band” and “empirical total capacity retention” are proposed though the comprehensive statistical analysis of the reviewed data. This review provides a comprehensive collection of information of state‐of‐the‐art and recent advancement in V2O5 and V2O5‐based composite materials for electrodes. Researchers could use the information to design and develop advanced electrodes for future batteries. 相似文献
17.
Between 20 and 10 million years ago, Miocene horses demonstrate rapid dental evolution from low-crowned (brachydont) to high-crowned (hypsodont) teeth. Hypsodonty is classically interpreted as an adaptive shift from browsing to grazing to exploit the spread of savanna grasses. Recent geochemical studies allow the use of carbon Isotopes to test this hypothesis. Isotopic analysis of fossil horse teeth Indicates a predominantly C3 diet consisting of mixed browse/grass or predominantly C3 grasses until the latest Miocene. The advent of C4 grassland ecosystems began about 7–8 million years ago and seems related to declining equid diversity. 相似文献
18.
ALEXANDER R. SCHMIDT VINCENT GIRARD VINCENT PERRICHOT WILFRIED SCHÖNBORN 《The Journal of eukaryotic microbiology》2010,57(3):245-248
ABSTRACT. Amber‐preserved shells of testate amoebae often provide as many diagnostic features as the tests of modern taxa. Most of these well‐preserved microfossils are morphologically assignable to modern species indicating either evolutionary stasis or convergent evolution. Here we describe two Lower Cretaceous testate amoebae that are clearly distinguishable from modern species. Centropyxis perforata n. sp. and Leptochlamys galippei n. sp. possessed perforate shells that were previously unknown in these genera. They are preserved in highly fossiliferous amber pieces from the Upper Albian (ca. 100 million years old) of Archingeay/Les Nouillers (Charente‐Maritime, southwestern France). Syninclusions of soil and litter dwelling arthropods and microorganisms indicate a limnetic‐terrestrial microhabitat at the floor of a coastal conifer forest. 相似文献
19.
Yu Huan Shouxiao Chen Rui Zeng Tao Wei Dehua Dong Xun Hu Yunhui Huang 《Liver Transplantation》2019,9(29)
Unveiling the intrinsic effects of Ruddlesden‐Popper (RP) series An+1BnO3n+1 (A = La, B = Ni, Co, Mn, Cu, n = 1, 2 and 3) catalysts is essential in order to optimize the activity of oxygen reduction reaction (ORR) and evolution reaction (OER). Here, it is demonstrated that the oxygen vacancy is not the key point for RP to realize high ORR and OER activity at high temperature. Instead, interstitial O2? with high concentration and fast migration, and lattice oxygen with high activity are favorable for the high‐temperature catalytic activity. Aliovalent cation doping is an effective strategy to modify the catalytic activity. For the RP catalysts, low‐valence ion doping does not introduce oxygen vacancies, which suppresses the activity of lattice oxygen and decreases the interstitial O2? concentration; whereas high‐valence ion doping enhances the interstitial O2– concentration and the lattice oxygen activity. The evaluations of six RP series (La2NiO4, La2CoO4, La3Co2O7, La4Ni3O10, La2MnO4, and La2CuO4 based) and twenty samples as oxygen electrodes for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) demonstrate that this finding is applicable to all the selected RP series. 相似文献
20.
Monkol Lek Kate G. R. Quinlan Kathryn N. North 《BioEssays : news and reviews in molecular, cellular and developmental biology》2010,32(1):17-25
In humans, there are two skeletal muscle α‐actinins, encoded by ACTN2 and ACTN3, and the ACTN3 genotype is associated with human athletic performance. Remarkably, approximately 1 billion people worldwide are deficient in α‐actinin‐3 due to the common ACTN3 R577X polymorphism. The α‐actinins are an ancient family of actin‐binding proteins with structural, signalling and metabolic functions. The skeletal muscle α‐actinins diverged ~250–300 million years ago, and ACTN3 has since developed restricted expression in fast muscle fibres. Despite ACTN2 and ACTN3 retaining considerable sequence similarity, it is likely that following duplication there was a divergence in function explaining why α‐actinin‐2 cannot completely compensate for the absence of α‐actinin‐3. This paper focuses on the role of skeletal muscle α‐actinins, and how possible changes in functions between these duplicates fit in the context of gene duplication paradigms. 相似文献