986 resultados para Cytochrom c Oxidase


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We have studied the kinetics of the oxygen reaction of the fully reduced quinol oxidase, cytochrome bo3, using flow-flash and stopped flow techniques. This enzyme belongs to the heme-copper oxidase family but lacks the CuA center of the cytochrome c oxidases. Depending on the isolation procedure, the kinetics are found to be either nearly monophasic and very different from those of cytochrome c oxidase or multiphasic and quite similar to cytochrome c oxidase. The multiphasic kinetics in cytochrome c oxidase can largely be attributed to the presence Of CuA as the donor of a fourth electron, which rereduces the originally oxidized low-spin heme and completes the reduction of O2 to water. Monophasic kinetics would thus be expected, a priori, for cytochrome bo3 since it lacks the CuA center, and in this case we show that the oxygen reaction is incomplete and ends with the ferryl intermediate. Multiphasic kinetics thus suggest the presence of an extra electron donor (analogous to CuA). We observe such kinetics exclusively with cytochrome bo3 that contains a single equivalent of bound ubiquinone-8, whereas we find no bound ubiquinone in an enzyme exhibiting monophasic kinetics. Reconstitution with ubiquinone-8 converts the reaction kinetics from monophasic to multiphasic. We conclude that a single bound ubiquinone molecule in cytochrome bo3 is capable of fast rereduction of heme b and that the reaction with O2 is quite similar in quinol and cytochrome c oxidases.

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One innovative thought in biomolecular electronics is the exploitation of electron transfer proteins. Using nature's self assembly techniques, proteins can build highly organized edifices with retained functional activity, and they can serve as platforms for biosensors. In this research work, Yeast Cytochrome C (YCC) is immobilized with a help of a linker molecule, 3-Mercaptopropyltrimethoxysilane (3-MPTS) on a hydroxylated surface of a silicon substrate. Atomic Force Microscopy (AFM) is used for characterization. AFM data shows immobilization of one YCC molecule in between eight grids that are formed by the linker molecules. 3-MPTS monolayers are organized in grids that are 1.2 nm apart. Immobilization of 3-MPTS was optimized using a concentration of 5 mM in a completely dehydrated state for 30 minutes. The functionally active grids of YCC can now be incorporated with Cytochrome C oxidase on a Platinum electrode surface for transfer of electrons in development of biosensors, such as nitrate sensor, that are small in size, cheaper, and easier to manufacture than the top-down approach of fabrication of molecular biodevices

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Background Bactrocera dorsalis s.s. is a pestiferous tephritid fruit fly distributed from Pakistan to the Pacific, with the Thai/Malay peninsula its southern limit. Sister pest taxa, B. papayae and B. philippinensis, occur in the southeast Asian archipelago and the Philippines, respectively. The relationship among these species is unclear due to their high molecular and morphological similarity. This study analysed population structure of these three species within a southeast Asian biogeographical context to assess potential dispersal patterns and the validity of their current taxonomic status. Results Geometric morphometric results generated from 15 landmarks for wings of 169 flies revealed significant differences in wing shape between almost all sites following canonical variate analysis. For the combined data set there was a greater isolation-by-distance (IBD) effect under a ‘non-Euclidean’ scenario which used geographical distances within a biogeographical ‘Sundaland context’ (r2 = 0.772, P < 0.0001) as compared to a ‘Euclidean’ scenario for which direct geographic distances between sample sites was used (r2 = 0.217, P < 0.01). COI sequence data were obtained for 156 individuals and yielded 83 unique haplotypes with no correlation to current taxonomic designations via a minimum spanning network. BEAST analysis provided a root age and location of 540kya in northern Thailand, with migration of B. dorsalis s.l. into Malaysia 470kya and Sumatra 270kya. Two migration events into the Philippines are inferred. Sequence data revealed a weak but significant IBD effect under the ‘non-Euclidean’ scenario (r2 = 0.110, P < 0.05), with no historical migration evident between Taiwan and the Philippines. Results are consistent with those expected at the intra-specific level. Conclusions Bactrocera dorsalis s.s., B. papayae and B. philippinensis likely represent one species structured around the South China Sea, having migrated from northern Thailand into the southeast Asian archipelago and across into the Philippines. No migration is apparent between the Philippines and Taiwan. This information has implications for quarantine, trade and pest management.

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Purpose: Exercise increases the production of reactive oxygen species (ROS) in skeletal muscle, and athletes often consume antioxidant supplements in the belief they will attenuate ROS-related muscle damage and fatigue during exercise. However, exercise-induced ROS may regulate beneficial skeletal muscle adaptations, such as increased mitochondrial biogenesis. We therefore investigated the effects of long-term antioxidant supplementation with vitamin E and alpha-lipoic acid on changes in markers of mitochondrial biogenesis in the skeletal muscle of exercise-trained and sedentary rats. Methods: Male Wistar rats were divided into four groups: 1) sedentary control diet, 2) sedentary antioxidant diet, 3) exercise control diet, and 4) exercise antioxidant diet. Animals ran on a treadmill 4 d.wk(-1) at similar to 70% V (over dot)O(2max) for up to 90 min.d(-1) for 14 wk. Results: Consistent with the augmentation of skeletal muscle mitochondrial biogenesis and antioxidant defenses, after training there were significant increases in peroxisome proliferator-activated receptor F coactivator 1 alpha (PGC-1 alpha) messenger RNA (mRNA) and protein, cytochrome C oxidase subunit IV (COX IV) and cytochrome C protein abundance, citrate synthase activity, Nfe2l2, and SOD2 protein (P < 0.05). Antioxidant supplementation reduced PGC-1 alpha mRNA, PGC-1 alpha and COX IV protein, and citrate synthase enzyme activity (P < 0.05) in both sedentary and exercise-trained rats. Conclusions: Vitamin E and alpha-lipoic acid supplementation suppresses skeletal muscle mitochondrial biogenesis, regardless of training status.

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Indicators of mitochondrial function were studied in two different cell culture models of cis-diamminedichloroplatinum-II (CDDP) resistance: the intrinsically resistant human ovarian cancer cell line CI-80-13S, and resistant clones (HeLa-S1a and HeLa-S1b) generated by stable expression of the serine protease inhibitor—plasminogen activator inhibitor type-2 (PAI-2), in the human cervical cancer cell line HeLa. In both models, CDDP resistance was associated with sensitivity to killing by adriamycin, etoposide, auranofin, bis[1,2-bis(diphenylphosphino)ethane]gold(I) chloride {[Au(DPPE)2]Cl}, CdCl2 and the mitochondrial inhibitors rhodamine-123 (Rhl23), dequalinium chloride (DeCH), tetraphenylphosphonium (TPP), and ethidium bromide (EtBr) and with lower constitutive levels of ATP. Unlike the HeLa clones, CI-80-13S cells were additionally sensitive to chloramphenicol, 1-methyl-4-phenylpyridinium ion (MPP+), rotenone, thenoyltrifluoroacetone (TTFA), and antimycin A, and showed poor reduction of 1-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), suggesting a deficiency in NADH dehydrogenase and/or succinate dehydrogenase activities. Total platinum uptake and DNA-bound platinum were slightly lower in CI-80-13S than in sensitive cells. The HeLa-S1a and HeLa-S1b clones, on the other hand, showed poor reduction of triphenyltetrazolium chloride (TTC), indicative of low cytochrome c oxidase activity. Total platinum uptake by HeLa-S1a was similar to HeLa, but DNA-bound platinum was much lower than for the parent cell line. The mitochondria of CI-80-13S and HeLa-S1a showed altered morphology and were fewer in number than those of JAM and HeLa. In both models, CDDP resistance was associated with less platinum accumulation and with mitochondrial and membrane defects, brought about one case with expression of a protease inhibitor which is implicated in tumor progression. Such markers may identify tumors suitable for treatment with gold phosphine complexes or other mitochondrial inhibitors.

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Indicators of mitochondrial function were studied in two different cell culture models of cis-diamminedichloroplatinum-II (CDDP) resistance: the intrinsically resistant human ovarian cancer cell line CI-80-13S, and resistant clones (HeLa-S1a and HeLa-S1b) generated by stable expression of the serine protease inhibitor—plasminogen activator inhibitor type-2 (PAI-2), in the human cervical cancer cell line HeLa. In both models, CDDP resistance was associated with sensitivity to killing by adriamycin, etoposide, auranofin, bis[1,2-bis(diphenylphosphino)ethane]gold(I) chloride {[Au(DPPE)2]Cl}, CdCl2 and the mitochondrial inhibitors rhodamine-123 (Rhl23), dequalinium chloride (DeCH), tetraphenylphosphonium (TPP), and ethidium bromide (EtBr) and with lower constitutive levels of ATP. Unlike the HeLa clones, CI-80-13S cells were additionally sensitive to chloramphenicol, 1-methyl-4-phenylpyridinium ion (MPP+), rotenone, thenoyltrifluoroacetone (TTFA), and antimycin A, and showed poor reduction of 1-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), suggesting a deficiency in NADH dehydrogenase and/or succinate dehydrogenase activities. Total platinum uptake and DNA-bound platinum were slightly lower in CI-80-13S than in sensitive cells. The HeLa-S1a and HeLa-S1b clones, on the other hand, showed poor reduction of triphenyltetrazolium chloride (TTC), indicative of low cytochrome c oxidase activity. Total platinum uptake by HeLa-S1a was similar to HeLa, but DNA-bound platinum was much lower than for the parent cell line. The mitochondria of CI-80-13S and HeLa-S1a showed altered morphology and were fewer in number than those of JAM and HeLa. In both models, CDDP resistance was associated with less platinum accumulation and with mitochondrial and membrane defects, brought about one case with expression of a protease inhibitor which is implicated in tumor progression. Such markers may identify tumors suitable for treatment with gold phosphine complexes or other mitochondrial inhibitors.

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Estrogen receptor (ER)-β has been shown to possess a tumor suppressive effect, and is a potential target for cancer therapy. Using gene-expression meta-analysis of human malignant pleural mesothelioma, we identified an ESR2 (ERβ coding gene) signature. High ESR2 expression was strongly associated with low succinate dehydrogenase B (SDHB) (which encodes a mitochondrial respiratory chain complex II subunit) expression. We demonstrate that SDHB loss induced ESR2 expression, and that activated ERβ, by over-expression or by selective agonist stimulation, negatively affected oxidative phosphorylation compromising mitochondrial complex II and IV activity. This resulted in reduced mitochondrial ATP production, increased glycolysis dependence and impaired cell proliferation. The observed in vitro effects were phenocopied in vivo using a selective ERβ agonist in a mesothelioma mouse model. On the whole, our data highlight an unforeseen interaction between ERβ-mediated tumor suppression and energy metabolism that may be exploited to improve on the therapy for clinical management of malignant mesothelioma.

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Since the 1950s, X-ray crystallography has been the mainstay of structural biology, providing detailed atomic-level structures that continue to revolutionize our understanding of protein function. From recent advances in this discipline, a picture has emerged of intimate and specific interactions between lipids and proteins that has driven renewed interest in the structure of lipids themselves and raised intriguing questions as to the specificity and stoichiometry in lipid-protein complexes. Herein we demonstrate some of the limitations of crystallography in resolving critical structural features of ligated lipids and thus determining how these motifs impact protein binding. As a consequence, mass spectrometry must play an important and complementary role in unraveling the complexities of lipid-protein interactions. We evaluate recent advances and highlight ongoing challenges towards the twin goals of (1) complete structure elucidation of low, abundant, and structurally diverse lipids by mass spectrometry alone, and (2) assignment of stoichiometry and specificity of lipid interactions within protein complexes.

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Population genetic studies of freshwater invertebrate taxa in New Zealand and South America are currently few despite the geologically and climatically dynamic histories of these regions. The focus of our study was a comparison of the influence on realized dispersal of 2 closely related nonbiting midges (Chironomidae) of population fragmentation on these separated austral land masses. We used a 734-base pair (bp) fragment of cytochrome c oxidase subunit I (COI) to investigate intraspecific genetic structure in Naonella forsythi Boothroyd in New Zealand and Ferringtonia patagonica Edwards in Patagonia. We proposed hypotheses about their potential dispersal and, hence, expected patterns of genetic structure in these 2 species based on published patterns for the closely related Australian taxon Echinocladius martini Cranston. Genetic structure revealed for both N. forsythi and F. patagonica was characterized by several highly divergent (2.0–10.5%) lineages of late Miocene–Pliocene age within each taxon that were not geographically localized. Many were distributed widely. This pattern differed greatly from population structure in E. martini, which was typified by much greater endemicity of divergent genetic lineages. Nevertheless, diversification of lineages in all 3 taxa appeared to be temporally congruent with the onset of late Miocene glaciations in the southern hemisphere that may have driven fragmentation of suitable habitat, promoting isolation of populations and divergence in allopatry. We argue that differences in realized dispersal post-isolation may be the result of differing availability of suitable habitat in interglacial periods.

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Laboratory confirmation methods are important in bovine cysticerosis diagnosis as other pathologies can result in morphologically similar lesions resulting in false identifications. We developed a probe-based real-time PCR assay to identify Taenia saginata in suspect cysts encountered at meat inspection and compared its use with the traditional method of identification, histology, as well as a published nested PCR. The assay simultaneously detects T. saginata DNA and a bovine internal control using the cytochrome c oxidase subunit 1 gene of each species and shows specificity against parasites causing lesions morphologically similar to those of T. saginata. The assay was sufficiently sensitive to detect 1 fg (Ct 35.09 +/- 0.95) of target DNA using serially-diluted plasmid DNA in reactions spiked with bovine DNA as well as in all viable and caseated positive control cysts. A loss in PCR sensitivity was observed with increasing cyst degeneration as seen in other molecular methods. In comparison to histology, the assay offered greater sensitivity and accuracy with 10/19 (53%) T. saginata positives detected by real-time PCR and none by histology. When the results were compared with the reference PCR, the assay was less sensitive but offered advantages of faster turnaround times and reduced contamination risk. Estimates of the assay's repeatability and reproducibility showed the assay is highly reliable with reliability coefficients greater than 0.94. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

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Nature has used a variety of protein systems to mediate electron transfer. In this thesis I examine aspects of the control of biological electron transfer by two copper proteins that act as natural electron carriers.

In the first study, I have made a mutation to one of the ligand residues in the azurin blue copper center, methionine 121 changed to a glutamic acid. Studies of intramolecular electron transfer rates from that mutated center to covalently attached ruthenium complexes indicate that the weak axial methionine ligand is important not only for tuning the reduction potential of the blue copper site but also for maintaining the low reorganization energy that is important for fast electron transfer at long distances.

In the second study, I begin to examine the reorganization energy of the purple copper center in the CuA domain of subunit II of cytochrome c oxidase. In this copper center, the unpaired electron is delocalized over the entire binuclear site. Because long-range electron transfer into and out of this center occurs over long distances with very small driving forces, the reorganization energy of the CuA center has been predicted to be extremely low. I describe a strategy for measuring this reorganization energy starting with the construction of a series of mutations introducing surface histidines. These histidines can then be labeled with a series of ruthenium compounds that differ primarily in their reduction potentials. The electron transfer rates to these ruthenium compounds can then be used to determine the reorganization energy of the CuA site.

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Este trabalho visou a averiguação do status taxonômico das esponjas bioerosivas do complexo Cliona celata da América do Sul por meio de técnicas moleculares, utilizando como marcadores a subunidade I da Citocromo c oxidase (cox1) e os Espaçadores Internos Transcritos do RNAr nuclear (ITS1 e ITS2), além de testar outros marcadores. Igualmente, avaliou o grau de variabilidade morfológica encontrado nessas espécies, principalmente por meio da morfometria dos tilóstilos, a fim de estabelecer uma diagnose para elas. Ainda, tentou determinar as relações filogenéticas dessas espécies com as demais esponjas bioerosivas utilizando o gene 28S do RNAr nuclear. Foi possível determinar a existência de cinco clados de esponjas bioerosivas do complexo Cliona celata para a América do Sul, e dois outros clados não-sulamericanos, por meio dos marcadores moleculares utilizados. Embora seja discutida a validade desses clados como espécies distintas, continua impossível, por meio de caracteres morfológicos, distingui-los, e dessa forma, a proposição formal de novas espécies é evitada. Através da reconstrução filogenética do grupo, é possível verificar que as esponjas bioerosivas analisadas se apresentaram como um grupo monofilético, e se separa em três principais clados: Pione, Spirastrellidae, e Clionaidae. Por meio desta, é sugerida a alocação das espécies do complexo C. viridis e C. schimidti dentro de Spirastrella, além de ser necessária a criação de um novo gênero para alocar as espécies do novo complexo identificado aqui, o complexo C. delitrix.

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Atlantic menhaden (Brevoortia tyrannus), through landings, support one of the largest commercial fisheries in the United States. Recent consolidation of the once coast-wide reduction fishery to waters within and around Chesapeake Bay has raised concerns over the possibility of the loss of unique genetic variation resulting from concentrated fishing pressure. To address this question, we surveyed variation at the mitochondrial cytochrome c oxidase subunit I (COI) gene region and seven nuclear microsatellite loci to evaluate stock structure of Atlantic menhaden. Samples were collected from up to three cohorts of Atlantic menhaden at four geographic locations along the U.S. Atlantic coast in 2006 and 2007, and from the closely related Gulf menhaden (B. patronus) in the Gulf of Mexico. Genetic divergence between Atlantic menhaden and Gulf menhaden, based on the COI gene region sequences and microsatellite loci, was more characteristic of conspecific populations than separate species. Hierarchical analyses of molecular variance indicated a homogeneous distribution of genetic variation within Atlantic menhaden. No significant variation was found between young-of-the-year menhaden (YOY) collected early and late in the season within Chesapeake Bay, between young-of-the-year and yearling menhaden collected in the Chesapeake Bay during the same year, between YOY and yearling menhaden taken in Chesapeake Bay in successive years, or among combined YOY and yearling Atlantic menhaden collected in both years from the four geographic locations. The genetic connectivity between the regional collections indicates that the concentration of fishing pressure in and around Chesapeake Bay will not result in a significant loss of unique genetic variation.

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Gundlachia Pfeiffer 1849 é o gênero de molusco de água doce pateliforme com a mais ampla distribuição geográfica dentre os oito gêneros de Ancylidae assinalados para a região Neotropical. A concha pateliforme, considerada uma homoplasia por diversos autores em vários basomatóforos, tem sido historicamente utilizada para definir a unidade da família Ancylidae, apesar dos questionamentos contrários à monofilia do grupo. Dados moleculares confirmaram que "Ancylidae" é um grupo parafilético, principalmente por causa do gênero Burnupia. Os demais gêneros foram incluídos em Ancylinae, dentro de Planorbidae. No entanto, a ausência de todos os gêneros Neotropicais nas filogenias propostas, com base molecular ainda é um assunto que necessita ser investigado. Os principais objetivos desse trabalho foram: (a) revisar as espécies de Gundlachia, através de estudos morfológicos das conchas e partes moles; (b) padronizar as descrições das espécies para iniciar uma análise cladística do gênero Gundlachia; (c) iniciar um estudo de biologia molecular utilizando distintas espécies de representantes de Ancylinae, para verificar as suas interrelações e o provável grupoirmão de Gundlachia; (d) e por fim, construir um mapa de distribuição geográfica. Para isso, examinamos diversas coleções científicas e realizamos coletas nas localidadestipo. A morfologia das conchas foi comparada por análises morfométricas e por microscópio de luz e de varredura. As partes moles dos espécimes foram dissecadas e estudadas sob o microscópio estereoscópico. A análise molecular foi realizada em três espécimes de cada amostra, utilizando os genes da citocromo c oxidase I e o 16S mtDNA. Após o sequenciamento verificamos as distâncias genéticas entre as diferentes espécies de Gundlachia e as suas relações com os outros gêneros por meio do teste Neighbor-joining e Maximum likelihood. Com esse estudo apresentamos a redescrição de algumas espécies de Gundlachia, discutimos a validade de novos táxons descobertos e sequenciamos e analisamos espécies de sete gêneros de Ancylinae que ocorrem na região Neotropical. Com base nesses dados discutimos a monofilia de Gundlachia e o seu provável grupo-irmão. E ainda abordamos a validade dos demais gêneros neotropicais

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Nos últimos anos, duas espécies de lagostas sapateiras, Scyllarides brasiliensis e S. deceptor, vêm se destacando nos desembarques pesqueiros de lagostas do Atlântico Sul Ocidental. Para espécies comercialmente importantes, o desenvolvimento de estudos que permitam conhecer a variabilidade e entender a dinâmica populacional é fundamental. Assim, o objetivo do primeiro capítulo desta tese foi avaliar a diversidade genética e a estrutura populacional dessas duas lagostas ao longo de aprox. 2.800 km da costa da América do Sul. Para as análises, foram empregados marcadores mitocondriais (citocromo oxidase I: COI; e a região controle: RC) e marcadores nucleares (13 loci de microssatélites desenvolvidos nesta tese). As duas espécies apresentaram altos níveis de variabilidade (S. deceptor: N = 200, mtDNA: h > 0,841, π > 0,005; microssatélites: He = 0,685; S. brasiliensis: N = 211, He = 0,554), distribuídos homogeneamente entre as localidades (S. deceptor: ΦST < -0,004, ΦCT < 0,016, FST global = 0,001, Dest global = 0,003, FCT < 0,002, P > 0,05, K = 1; S. brasiliensis: FST global = 0,004, Dest global = 0,001, FCT < 0,004, P > 0,05, K = 1). A ausência de estruturação nas duas espécies pode estar relacionada a características biológicas que promovem a conectividade entre localidades geograficamente distantes, como alta fecundidade e alto potencial de dispersão das larvas planctônicas. Além disso, os dados mitocondriais sugerem que a história demográfica de S. deceptor foi marcada por eventos de expansão populacionais e geográficos possivelmente relacionados às condições ambientais favoráveis dos episódios interglaciais do Pleistoceno Médio-Tardio. Diversos estudos têm mostrado que os fenômenos de inserção de regiões mitocondriais no DNA nuclear (NuMts) e heteroplasmia limitam a correta amplificação e identificação dos marcadores mitocondriais. Em estudos filogenéticos e de genética de populações, a presença inadvertida de sequências de diversas origens viola o principio de ortologia, o que pode resultar em inferências evolutivas erradas. Assim, o objetivo do segundo capítulo desta tese foi identificar e caracterizar os possíveis NuMts e sequências heteroplásmicas de três regiões mitocondriais (COI, RC e o gene da subunidade maior do RNA ribossomal: 16S) em quatro espécies do gênero Scyllarides (S. aequinoctialis, S. brasiliensis, S. deceptor e S. delfosi). A clonagem e sequenciamento de extratos de DNA genômico e DNA enriquecido com mtDNA revelaram que os genomas destas espécies podem exibir NuMts (que divergem entre 0,6 e 17,6% do mtDNA) e heteroplasmia (que divergem < 0,2% do mtDNA prevalente). Os NuMts surgiram possivelmente de vários eventos independentes de integração ao núcleo ao longo da história evolutiva do gênero Scyllarides. Dependendo do seu grau de similaridade com o mtDNA, a presença de NuMts nas análises filogenéticas no nível de gênero pode causar superestimativa do número de espécies e alterações nos comprimentos dos ramos e nas relações filogenéticas entre espécies.