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1.
Int J Mol Med ; 50(5)2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36129150

RESUMO

Subsequently to the publication of the above paper, an interested reader drew to the authors' attention that, in Fig. 3B on p. 1092, the western blots shown for 'Bax' in the MCF-7 group and 'Cleaved Caspase-8' in the MDA-MB-231 group were strikingly similar, such that these may have been the identical data re-used in the same figure. The authors have subsequently re­examined their data, and realize that the Cleaved Caspase-8 blots were incorrectly used in Fig. 3B during the process of assembling this figure (i.e., the western blots were duplicated, and these were correctly shown as the data for Bax in the MCF-7 group). Furthermore, the authors have realized that the western blots selected for the Cleaved Caspase-3 experiment in the western blots shown in Fig. 5D on p. 1093 were not as clear as they could have been, and also requested that the data here be changed for those from one of the repeated experiments. Consequently, the revised versions of Figs. 3 and 5, containing the correct data for the Cleaved Caspase-8 blots in the MDA-MB-231 group in Fig. 3B and the replacement Cleaved Caspase-3 blots in Fig. 5C, are shown on the next page. These errors did not affect the major conclusions reported in the paper. All the authors agree to the publication of this corrigendum, and thank the Editor of International Journal of Molecular Medicine for allowing them the opportunity to publish this. The authors regret the error that went unnoticed during the compilation of the figures in question, and apologize to the readership for any confusion that this may have caused. [International Journal of Molecular Medicine 40: 1089-1095, 2017; DOI: 10.3892/ijmm.2017.3081].

2.
Evolution ; 74(12): 2662-2680, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32886353

RESUMO

Ecology and biomechanics play central roles in the generation of phenotypic diversity. When unrelated taxa invade a similar ecological niche, biomechanical demands can drive convergent morphological transformations. Thus, examining convergence helps to elucidate the key catalysts of phenotypic change. Gliding mammals are often presented as a classic case of convergent evolution because they independently evolved in numerous clades, each possessing patagia ("wing" membranes) that generate lift during gliding. We use phylogenetic comparative methods to test whether the skeletal morphologies of the six clades of extant gliding mammals demonstrate convergence. Our results indicate that glider skeletons are convergent, with glider groups consistently evolving proportionally longer, more gracile limbs than arborealists, likely to increase patagial surface area. Nonetheless, we interpret gliders to represent incomplete convergence because (1) evolutionary model-fitting analyses do not indicate strong selective pressures for glider trait optima, (2) the three marsupial glider groups diverge rather than converge, and (3) the gliding groups remain separated in morphospace (rather than converging on a single morphotype), which is reflected by an unexpectedly high level of morphological disparity. That glider skeletons are morphologically diverse is further demonstrated by fossil gliders from the Mesozoic Era, which possess unique skeletal characteristics that are absent in extant gliders. Glider morphologies may be strongly influenced by factors such as body size and attachment location of patagia on the forelimb, which can vary among clades. Thus, convergence in gliders appears to be driven by a simple lengthening of the limbs, whereas additional skeletal traits reflect nuances of the gliding apparatus that are distinct among different evolutionary lineages. Our unexpected results add to growing evidence that incomplete convergence is prevalent in vertebrate clades, even among classic cases of convergence, and they highlight the importance of examining form-function relationships in light of phylogeny, biomechanics, and the fossil record.


Assuntos
Adaptação Biológica , Evolução Biológica , Locomoção , Mamíferos/anatomia & histologia , Esqueleto , Animais , Comportamento Animal , Fósseis
3.
Anat Rec (Hoboken) ; 303(4): 716-731, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31825173

RESUMO

The Early Cretaceous (∼131 Million Years Ago) Protopteryx fengningensis is one of the oldest and most primitive enantiornithine birds; however, knowledge of its anatomy has largely been limited to the succinct description of two specimens (holotype and paratype). This study describes two new specimens of P. fengningensis preserving most of the skeleton and plumage, and it therefore adds significantly to understanding the morphology of this important species and the character evolution of enantiornithine birds. The well-preserved plumage of these specimens also affords a quantitative assessment of the flight performance of P. fengningensis. Our aerodynamic considerations indicate that this early enantiornithine was capable of intermittent flight (bounding or flap-gliding), thus marking the earliest occurrence of such energy-saving aerial strategy. Anat Rec, 303:716-731, 2020. © 2019 American Association for Anatomy.


Assuntos
Evolução Biológica , Aves/anatomia & histologia , Osso e Ossos/anatomia & histologia , Voo Animal/fisiologia , Filogenia , Animais , China , Fósseis
4.
Nature ; 548(7667): 291-296, 2017 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-28792929

RESUMO

Stem mammaliaforms are Mesozoic forerunners to mammals, and they offer critical evidence for the anatomical evolution and ecological diversification during the earliest mammalian history. Two new eleutherodonts from the Late Jurassic period have skin membranes and skeletal features that are adapted for gliding. Characteristics of their digits provide evidence of roosting behaviour, as in dermopterans and bats, and their feet have a calcaneal calcar to support the uropagatium as in bats. The new volant taxa are phylogenetically nested with arboreal eleutherodonts. Together, they show an evolutionary experimentation similar to the iterative evolutions of gliders within arboreal groups of marsupial and placental mammals. However, gliding eleutherodonts possess rigid interclavicle-clavicle structures, convergent to the avian furculum, and they retain shoulder girdle plesiomorphies of mammaliaforms and monotremes. Forelimb mobility required by gliding occurs at the acromion-clavicle and glenohumeral joints, is different from and convergent to the shoulder mobility at the pivotal clavicle-sternal joint in marsupial and placental gliders.


Assuntos
Fósseis , Locomoção , Mamíferos/anatomia & histologia , Mamíferos/fisiologia , Filogenia , Animais , Aves/anatomia & histologia , China , Quirópteros/anatomia & histologia , Quirópteros/fisiologia , Dieta , Membro Anterior/anatomia & histologia , Membro Anterior/fisiologia , Mamíferos/classificação , Marsupiais/fisiologia , Dente Molar/anatomia & histologia , Dente Molar/fisiologia , Ombro/anatomia & histologia , Pele/anatomia & histologia , Crânio/anatomia & histologia
5.
Int J Mol Med ; 40(4): 1089-1095, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28765878

RESUMO

Grifola frondosa, a type of food and medical fungus, has been shown to exhibit various pharmacological activities, including anticancer effects. As the most typical cancer diagnosed among female patients, breast cancer remains a huge concern threatening human health globally. In the present study, the anti-breast cancer effects of Grifola frondosa polysaccharides (GFPs) and the underlying mechanisms were investigated in MCF-7 and MDA-MB-231 cells, as well as in nude mice bearing MCF-7 tumor xenografts. GFPs exerted cytotoxic effects on the cells, as indicated by a decrease in cell viability, and an increase in the apoptototic rate, lactate dehydrogenase release and reactive oxygen species accumulation, inducing mitochondrial dysfunction. The increased expression of Bax, cleaved caspase-3 and caspase-8, and the reduced levels of B-cell lymphoma 2 (Bcl-2) and Bcl-extra large (Bcl­xL) were observed in the cells incubated with GFPs and in the tumor tissues of the mice treated with GFPs. Moreover, the GFPs significantly suppressed the phosphorylation of AKT/glycogen synthase kinase-3ß and extracellular signal-regulated kinases in a time-dependent manner. Finally, the inhibition of MCF-7 tumor xenograft growth further confirmed the anti-breast cancer effects of GFPs. All these findings revealed that GFPs induced human breast cancer cell apoptosis via the mitochondrial-dependent apoptotic pathway, and provide experimental evidence to support the use of Grifola frondosa as a potential treatment for breast cancer.


Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Polissacarídeos Fúngicos/farmacologia , Regulação Neoplásica da Expressão Gênica , Grifola/química , Mitocôndrias/efeitos dos fármacos , Animais , Antineoplásicos/isolamento & purificação , Apoptose/efeitos dos fármacos , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Caspase 3/genética , Caspase 3/metabolismo , Caspase 8/genética , Caspase 8/metabolismo , Linhagem Celular Tumoral , Feminino , Polissacarídeos Fúngicos/isolamento & purificação , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , Células MCF-7 , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Mitocôndrias/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Transdução de Sinais , Carga Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo , Proteína bcl-X/genética , Proteína bcl-X/metabolismo
6.
Nature ; 548(7667): 326-329, 2017 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-28792934

RESUMO

Stem mammaliaforms are forerunners to modern mammals, and they achieved considerable ecomorphological diversity in their own right. Recent discoveries suggest that eleutherodontids, a subclade of Haramiyida, were more species-rich during the Jurassic period in Asia than previously recognized. Here we report a new Jurassic eleutherodontid mammaliaform with an unusual mosaic of highly specialized characteristics, and the results of phylogenetic analyses that support the hypothesis that haramiyidans are stem mammaliaforms. The new fossil shows fossilized skin membranes that are interpreted to be for gliding and a mandibular middle ear with a unique character combination previously unknown in mammaliaforms. Incisor replacement is prolonged until well after molars are fully erupted, a timing pattern unique to most other mammaliaforms. In situ molar occlusion and a functional analysis reveal a new mode of dental occlusion: dual mortar-pestle occlusion of opposing upper and lower molars, probably for dual crushing and grinding. This suggests that eleutherodontids are herbivorous, and probably specialized for granivory or feeding on soft plant tissues. The inferred dietary adaptation of eleutherodontid gliders represents a remarkable evolutionary convergence with herbivorous gliders in Theria. These Jurassic fossils represent volant, herbivorous stem mammaliaforms associated with pre-angiosperm plants that appear long before the later, iterative associations between angiosperm plants and volant herbivores in various therian clades.


Assuntos
Aclimatação , Evolução Biológica , Orelha Média/anatomia & histologia , Ingestão de Alimentos , Ecossistema , Fósseis , Mamíferos/anatomia & histologia , Mamíferos/fisiologia , Animais , Dieta , Herbivoria , Incisivo , Locomoção , Mamíferos/classificação , Dente Molar , Filogenia
7.
Nat Commun ; 8: 14972, 2017 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-28463233

RESUMO

Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Here we report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical features that are transitional between long-armed basal troodontids and derived short-armed ones, shedding new light on troodontid character evolution. It indicates that troodontid feathering is similar to Archaeopteryx in having large arm and leg feathers as well as frond-like tail feathering, confirming that these feathering characteristics were widely present among basal paravians. Most significantly, the taxon has the earliest known asymmetrical troodontid feathers, suggesting that feather asymmetry was ancestral to Paraves. This taxon also displays a mosaic distribution of characters like Sinusonasus, another troodontid with transitional anatomical features.


Assuntos
Evolução Biológica , Dinossauros/anatomia & histologia , Plumas/anatomia & histologia , Fósseis/anatomia & histologia , Filogenia , Animais , China , Dinossauros/classificação , Dinossauros/fisiologia , Extinção Biológica , Plumas/fisiologia , Voo Animal/fisiologia , Fósseis/história , História Antiga , Software
8.
Neurosci Lett ; 628: 105-9, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-27038516

RESUMO

Albiflorin (AF), one of important bioactive constituents of Paeonia lactiflora Radix, possesses neuro-protective effect. The present study aims to investigate the antinociceptive activities of AF and possible mechanisms. AF suppressed acetic acid-caused writhing, lengthened the latency period of mouse in hot plate test, and reduced the licking and biting response time of the injected mouse paw during phase I and phase II, and it suggested that AF exerted the antinociceptive activity mainly through central nervous system. Nimodipine, a commonly used calcium channels blocker, strongly lengthened AF-enhanced latency period of mouse in hot plate test. Compared with control group, AF reduced the levels of euronal nitric oxide synthase (nNOS), and enhanced the levels of serotonin (5-HT) in serum and/or hypothalamus before and after 30-s thermal stimuli. The reduced activation of calmodulin-dependent protein kinase II and c-Jun N-terminal kinase in hypothalamus was observed in AF-treated mice. Collectively, AF-mediated antinociceptive activities were, at least partially, related to calcium channels.


Assuntos
Analgésicos/administração & dosagem , Hidrocarbonetos Aromáticos com Pontes/administração & dosagem , Canais de Cálcio/fisiologia , Nociceptividade/efeitos dos fármacos , Nociceptividade/fisiologia , Animais , Bloqueadores dos Canais de Cálcio/administração & dosagem , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Nimodipina/administração & dosagem , Óxido Nítrico Sintase Tipo I/sangue , Medição da Dor , Serotonina/sangue
9.
Sci Rep ; 5: 15202, 2015 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-26512629

RESUMO

The relationship between tooth form and dietary preference is a crucial issue in vertebrate evolution. However, the mechanical properties of a tooth are influenced not only by its shape but also by its internal structure. Here, we use synchrotron transmission X-ray microscopy to examine the internal microstructures of multiple dinosaur teeth within a phylogenetic framework. We found that the internal microstructures of saurischian teeth are very different from advanced ornithischian teeth, reflecting differences in dental developmental strategies. The three-tissue composition (enamel-mantle dentin-bulk dentin) near the dentinoenamel junction (DEJ) in saurischian teeth represents the primitive condition of dinosaur teeth. Mantle dentin, greatly reduced or absent from DEJ in derived ornithischian teeth, is a key difference between Saurischia and Ornithischia. This may be related to the derived herbivorous feeding behavior of ornithischians, but interestingly, it is still retained in the herbivorous saurischian sauropods. The protective functions of mantle dentin with porous microstructures between enamel and bulk dentin inside typical saurischian teeth are also discussed using finite-element analysis method. Evolution of the dental modifications in ornithischian dinosaurs, with the absence of mantle dentin, may be related to changes in enamel characteristics with enamel spindles extending through the DEJ.


Assuntos
Evolução Biológica , Dentina/diagnóstico por imagem , Animais , Dentina/ultraestrutura , Dinossauros/classificação , Fósseis , Imageamento Tridimensional , Microscopia Eletrônica de Varredura , Filogenia , Porosidade , Radiografia , Síncrotrons , Raios X
10.
Science ; 347(6223): 760-4, 2015 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-25678660

RESUMO

A new Late Jurassic docodontan shows specializations for a subterranean lifestyle. It is similar to extant subterranean golden moles in having reduced digit segments as compared to the ancestral phalangeal pattern of mammaliaforms and extant mammals. The reduction of digit segments can occur in mammals by fusion of the proximal and intermediate phalangeal precursors, a developmental process for which a gene and signaling network have been characterized in mouse and human. Docodontans show a positional shift of thoracolumbar ribs, a developmental variation that is controlled by Hox9 and Myf5 genes in extant mammals. We argue that these morphogenetic mechanisms of modern mammals were operating before the rise of modern mammals, driving the morphological disparity in the earliest mammaliaform diversification.


Assuntos
Evolução Biológica , Falanges dos Dedos da Mão/anatomia & histologia , Falanges dos Dedos da Mão/crescimento & desenvolvimento , Mamíferos/anatomia & histologia , Mamíferos/crescimento & desenvolvimento , Morfogênese/fisiologia , Animais , China , Pé/anatomia & histologia , Pé/crescimento & desenvolvimento , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/fisiologia , Humanos , Mamíferos/genética , Camundongos , Morfogênese/genética , Fator Regulador Miogênico 5/genética , Fator Regulador Miogênico 5/fisiologia
11.
Science ; 347(6223): 764-8, 2015 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-25678661

RESUMO

A new docodontan mammaliaform from the Middle Jurassic of China has skeletal features for climbing and dental characters indicative of an omnivorous diet that included plant sap. This fossil expands the range of known locomotor adaptations in docodontans to include climbing, in addition to digging and swimming. It further shows that some docodontans had a diet with a substantial herbivorous component, distinctive from the faunivorous diets previously reported in other members of this clade. This reveals a greater ecological diversity in an early mammaliaform clade at a more fundamental taxonomic level not only between major clades as previously thought.


Assuntos
Biodiversidade , Dentição , Herbivoria , Mamíferos/classificação , Mamíferos/crescimento & desenvolvimento , Ração Animal , Animais , China , Dente Canino/anatomia & histologia , Dente Canino/imunologia , Membro Anterior/anatomia & histologia , Membro Anterior/crescimento & desenvolvimento , Incisivo/anatomia & histologia , Incisivo/crescimento & desenvolvimento , Mamíferos/anatomia & histologia , Mandíbula/anatomia & histologia , Mandíbula/crescimento & desenvolvimento , Filogenia
12.
Zootaxa ; 3884(3): 253-66, 2014 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-25543783

RESUMO

We describe a new ornithuromorph bird species, Gansus zheni from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation (Jehol Group), Liaoning Province, China. A cladistic analysis resolves Gansus zheni as the sister taxon of the roughly contemporaneous Gansus yumenensis (Xiagou Formation, Gansu Province), and together as the most immediate outgroup to Ornithurae. Gansus zheni is the most advanced bird known today for the Jehol Biota. Its discovery provides the best-documented case of inter-basinal correlations (Jehol and Changma basins of Liaoning and Gansu provinces, respectively) using low-taxonomic clades of fossil birds. The existence of close relatives of Ornithurae in deposits formed at about 120 million years ago helps to mitigate the long-standing controversy between molecular and paleontological evidence for the temporal divergence of modern birds (Neornithes).


Assuntos
Evolução Biológica , Aves/classificação , Animais , Aves/anatomia & histologia , China , Fósseis/anatomia & histologia , Filogenia
13.
Nature ; 507(7492): 350-3, 2014 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-24522537

RESUMO

Inference of colour patterning in extinct dinosaurs has been based on the relationship between the morphology of melanin-containing organelles (melanosomes) and colour in extant bird feathers. When this relationship evolved relative to the origin of feathers and other novel integumentary structures, such as hair and filamentous body covering in extinct archosaurs, has not been evaluated. Here we sample melanosomes from the integument of 181 extant amniote taxa and 13 lizard, turtle, dinosaur and pterosaur fossils from the Upper-Jurassic and Lower-Cretaceous of China. We find that in the lineage leading to birds, the observed increase in the diversity of melanosome morphologies appears abruptly, near the origin of pinnate feathers in maniraptoran dinosaurs. Similarly, mammals show an increased diversity of melanosome form compared to all ectothermic amniotes. In these two clades, mammals and maniraptoran dinosaurs including birds, melanosome form and colour are linked and colour reconstruction may be possible. By contrast, melanosomes in lizard, turtle and crocodilian skin, as well as the archosaurian filamentous body coverings (dinosaur 'protofeathers' and pterosaur 'pycnofibres'), show a limited diversity of form that is uncorrelated with colour in extant taxa. These patterns may be explained by convergent changes in the key melanocortin system of mammals and birds, which is known to affect pleiotropically both melanin-based colouration and energetic processes such as metabolic rate in vertebrates, and may therefore support a significant physiological shift in maniraptoran dinosaurs.


Assuntos
Evolução Biológica , Dinossauros/fisiologia , Plumas , Melanossomas/fisiologia , Pigmentação , Jacarés e Crocodilos/anatomia & histologia , Animais , Aves/anatomia & histologia , China , Extinção Biológica , Plumas/citologia , Fósseis , Cor de Cabelo , Tegumento Comum/anatomia & histologia , Tegumento Comum/fisiologia , Lagartos/anatomia & histologia , Mamíferos/anatomia & histologia , Melaninas/metabolismo , Melanossomas/ultraestrutura , Pigmentação da Pele , Tartarugas/anatomia & histologia
14.
PeerJ ; 2: e234, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24482756

RESUMO

The discovery of Hongshanornis longicresta, a small ornithuromorph bird with unusually long hindlimb proportions, was followed by the discovery of two closely related species, Longicrusavis houi and Parahongshanornis chaoyangensis. Together forming the Hongshanornithidae, these species reveal important information about the early diversity and morphological specialization of ornithuromorphs, the clade that contains all living birds. Here we report on a new specimen (DNHM D2945/6) referable to Hongshanornis longicresta that contributes significant information to better understand the morphology, trophic ecology, and aerodynamics of this species, as well as the taxonomy of the Hongshanornithidae. Most notable are the well-preserved wings and feathered tail of DNHM D2945/6, which afford an accurate reconstruction of aerodynamic parameters indicating that as early as 125 million years ago, basal ornithuromorphs had evolved aerodynamic surfaces comparable in size and design to those of many modern birds, and flight modes alike to those of some small living birds.

15.
Science ; 341(6147): 779-83, 2013 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-23950536

RESUMO

Multituberculates were successful herbivorous mammals and were more diverse and numerically abundant than any other mammal groups in Mesozoic ecosystems. The clade also developed diverse locomotor adaptations in the Cretaceous and Paleogene. We report a new fossil skeleton from the Late Jurassic of China that belongs to the basalmost multituberculate family. Dental features of this new Jurassic multituberculate show omnivorous adaptation, and its well-preserved skeleton sheds light on ancestral skeletal features of all multituberculates, especially the highly mobile joints of the ankle, crucial for later evolutionary success of multituberculates in the Cretaceous and Paleogene.


Assuntos
Evolução Biológica , Fósseis , Mamíferos , Adaptação Biológica , Animais , Fenômenos Biomecânicos , Osso e Ossos/anatomia & histologia , China , Dentição , Articulações/anatomia & histologia , Articulações/fisiologia , Locomoção , Mamíferos/anatomia & histologia , Mamíferos/classificação , Mamíferos/fisiologia , Mandíbula/anatomia & histologia , Paleodontologia , Filogenia , Dente/anatomia & histologia
16.
Dalton Trans ; 42(23): 8241-8, 2013 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-23584605

RESUMO

Three coordination polymers {[Co2(AQTC)(H2O)6]·6H2O}n (1), {[M2(AQTC)(bpym)(H2O)6]·6H2O}n (M = Co(2), Ni(3)) have been synthesized and structurally characterized, where H4AQTC is anthraquinone-1,4,5,8-tetracarboxylic acid and bpym is 2,2'-bipyrimidine. Complex 1 features a 3-D structure, where layers of Co2(AQTC) are cross-linked by Co-H2O chains. Complexes 2 and 3 are isostructural and display 1-D chain structures. The chains are connected through hydrogen-bonding interactions to form 3-D supramolecular structures. Magnetic properties of these complexes are investigated. Compound 1 shows canted antiferromagnetism and slow relaxation below 4.0 K. For complexes 2 and 3, dominant antiferromagnetic interactions are observed. The luminescent properties of the three complexes are investigated as well.

17.
Curr Biol ; 22(23): 2262-7, 2012 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-23177480

RESUMO

In modern birds (Neornithes), the wing is composed of a layer of long, asymmetrical flight feathers overlain by short covert feathers. It has generally been assumed that wing feathers in the Jurassic bird Archaeopteryx and Cretaceous feathered dinosaurs had the same arrangement. Here, we redescribe the wings of the archaic bird Archaeopteryx lithographica and the dinosaur Anchiornis huxleyi and show that their wings differ from those of Neornithes in being composed of multiple layers of feathers. In Archaeopteryx, primaries are overlapped by long dorsal and ventral coverts. Anchiornis has a similar configuration but is more primitive in having short, slender, symmetrical remiges. Archaeopteryx and Anchiornis therefore appear to represent early experiments in the evolution of the wing. This primitive configuration has important functional implications: although the slender feather shafts of Archaeopteryx and Anchiornis make individual feathers weak, layering of the wing feathers may have produced a strong airfoil. Furthermore, the layered arrangement may have prevented the feathers from forming a slotted tip or separating to reduce drag on the upstroke. The wings of early birds therefore may have lacked the range of functions seen in Neornithes, limiting their flight ability.


Assuntos
Aves/anatomia & histologia , Dinossauros/anatomia & histologia , Plumas , Fósseis , Asas de Animais/anatomia & histologia , Animais , Evolução Biológica , Aves/fisiologia , Dinossauros/fisiologia , Asas de Animais/fisiologia
18.
Science ; 335(6073): 1215-9, 2012 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-22403389

RESUMO

Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinctly narrow. Quantitative comparison of these data with melanosome imprints densely sampled from a previously unknown specimen of the Early Cretaceous feathered Microraptor predicts that its plumage was predominantly iridescent. The capacity for simple iridescent arrays is thus minimally inferred in paravian dinosaurs. This finding and estimation of Microraptor feathering consistent with an ornamental function for the tail suggest a centrality for signaling in early evolution of plumage and feather color.


Assuntos
Evolução Biológica , Aves/anatomia & histologia , Dinossauros/anatomia & histologia , Plumas/ultraestrutura , Melanossomas/ultraestrutura , Pigmentação , Animais , China , Cor , Análise Discriminante , Plumas/anatomia & histologia , Queratinas/análise , Queratinas/química , Melaninas/análise , Melaninas/química , Filogenia
19.
Dalton Trans ; 40(44): 11788-94, 2011 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-21971299

RESUMO

A unique tubular molecular-assembly, constructed by ß-cyclodextrin and Na[Ni(mnt)(2)], was identified by X-ray crystallography. Inclusion complex Na[Ni(mnt)(2)]@ß-cyclodextrin (1) crystallized in space group P2(1)2(1)2 as hydrated head-to-head, tail-to-tail, and head-to-tail host pipelines with negatively charged [Ni(mnt)(2)](-) guests included, exhibiting a 3 : 1 (host : guest) stoichiometry. The hydrophilic transition-metal coordination compound (Na[Ni(mnt)(2)]) was embedded within a hydrophobic cyclodextrin cavity, which resulted in a ß-cyclodextrin trimer motif and one-third "empty" host packing model in the crystal. Induced circular dichroism (ICD) spectra of inclusion complex 1 was investigated, which indicated the same penetration pattern of the guests in host cavities in solution phase as that discovered in the crystal structure. In addition, PM3 quantum chemistry calculations strongly supported the co-conformational alignments of inclusion complex 1 that was identified in the crystal as well as in the solution.


Assuntos
Complexos de Coordenação/química , Níquel/química , Compostos de Sulfidrila/química , beta-Ciclodextrinas/química , Cristalografia por Raios X , Interações Hidrofóbicas e Hidrofílicas , Conformação Molecular , Teoria Quântica
20.
Chemistry ; 17(36): 9936-43, 2011 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-22003503

RESUMO

The reactions of methylenediisophthalic acid (H4L) and N-auxiliary ligands (1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethane) with transition-metal centers (Co2+/Mn2+) have given rise to four unprecedented polythreading coordination polymers. Single-crystal X-ray diffraction analyses revealed that the compounds can be described as 3D2− ⊂2[1D2+] + 2D6− for 1, 3D4− ⊂1D2+ + 1D6− for 2, and 2D4− ⊂0D2+ + 2[1D3−] for 3 and 4. All the polymers are formed through the assembly of two kinds of motifs with opposite charges. Noncentrosymmetric structures and multifunctionality in 2­4 are established by varying ligands and metal centers. Spontaneous resolution upon crystallization occurred in compounds 3 and 4 in the absence of any chiral source. The enantiomers of 3 and 4 consist of three chiral building blocks of L4−/HL3− and Mn2+ centers. In the solid state, polar compounds 2­4 exhibit nonlinear-optic (NLO) and ferroelectric properties at room temperature. The assembly of two kinds of motifs with opposite charges provides a useful method for the preparation of multifunctional compounds.

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