3,207 research outputs found
The great saphenous vein-an anatomical study.
The anatomical variations are more frequently encountered in the venous system particularly in the superficial veins when compared to the arterial system. The great saphenous vein is the longest vein of the body and represents pre-axial vein of lower limb. The venous anatomy is of great importance to the surgeons and sonographers. The present study included 25 lower limbs during routine dissection for undergraduate students in the Department of Anatomy, Kasturba Medical College, Manipal, India. We studied the great saphenous vein with reference to its formation, relation with the medial malleolus, distance from patella, level of termination and variation in its major tributaries. The findings were recorded, tabulated and photographed. Aforementioned anatomical facts including mode of termination of great saphenous vein can be important for surgeons planning intervention in this area. This vein is used as an arterial graft because of the marked anatomical remodeling. Thus, a good understanding of the typical ultrasound appearance of the great saphenous vein, its relationship to the major bony landmarks is significant
Multiple rearrangements in cryptic species of electric knifefish, Gymnotus carapo (Gymnotidae, Gymnotiformes) revealed by chromosome painting.
BACKGROUND: Gymnotus (Gymnotidae, Gymnotiformes) is the Neotropical electric fish genus with the largest geographic distribution and the largest number of species, 33 of which have been validated. The diploid number varies from 2n = 39-40 to 2n = 54. Recently we studied the karyotype of morphologically indistinguishable samples from five populations of G. carapo sensu stricto from the Eastern Amazon of Brazil. We found two cytotypes, 2n = 42 (30 M/SM + 12 ST/A) and 2n = 40 (34 M/SM + 6 ST/A) and we concluded that the differences between the two cryptic species are due to pericentric inversions and one tandem fusion. RESULTS: In this study we use for the first time, whole chromosome probes prepared by FACS of the Gymnotus carapo sensu strictu species, cytotype with 2n = 42. Using two color hybridizations we were able to distinguish pairs 1, 2, 3, 7, 9, 14, 16, 18, 19, 20 and 21. It was not possible to separate by FACS and distinguish each of the following chromosome pairs even with dual color FISH: {4,8}; {10,11}; {5,6,17}; {12,13,15}. The FISH probes were then used in chromosome painting experiments on metaphases of the 2n = 40 cytotype. While some chromosomes show conserved synteny, others are rearranged in different chromosomes. Eight syntenic associations were found. CONCLUSIONS: These results show that the karyotype differences between these cryptic species are greater than assumed by classical cytogenetics. These data reinforce the previous supposition that these two cytotypes are different species, despite the absence of morphological differences. Additionally, the homology of repetitive DNA between the two provides evidence of recent speciation.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Contribution of microscopy for understanding the mechanism of action against trypanosomatids
Transmission electron microscopy (TEM) has proved to be a useful tool to study the ultrastructural alterations and the target organelles of new antitrypanosomatid drugs. Thus, it has been observed that sesquiterpene lactones induce diverse ultrastructural alterations in both T. cruzi and Leishmania spp., such as cytoplasmic vacuolization, appearance of multilamellar structures, condensation of nuclear DNA, and, in some cases, an important accumulation of lipid vacuoles. This accumulation could be related to apoptotic events. Some of the sesquiterpene lactones (e.g., psilostachyin) have also been demonstrated to cause an intense mitochondrial swelling accompanied by a visible kinetoplast deformation as well as the appearance of multivesicular bodies. This mitochondrial swelling could be related to the generation of oxidative stress and associated to alterations in the ergosterol metabolism. The appearance of multilamellar structures and multiple kinetoplasts and flagella induced by the sesquiterpene lactone psilostachyin C indicates that this compound would act at the parasite cell cycle level, in an intermediate stage between kinetoplast segregation and nuclear division. In turn, the diterpene lactone icetexane has proved to induce the external membrane budding on T. cruzi together with an apparent disorganization of the pericellar cytoskeleton. Thus, ultrastructural TEM studies allow elucidating the possible mechanisms and the subsequent identification of molecular targets for the action of natural compounds on trypanosomatids.Fil: Lozano, Esteban Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Spina Zapata, Renata María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Barrera, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Tonn, Carlos Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Sosa Escudero, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentin
Custo de produção de mudas clonais de Café Arábica produzidas por embriogênese somática
A produção de mudas clonais de café pode ser feita de diferentes formas. Entretanto, a produção por embriogênese somática é a que tem despontado como a mais promissora. A embriogênese somática permite a produção de mudas em larga escala a partir de folhas usadas como explantes. Plantas obtidas por esse processo apresentam comportamento semelhante ao de plantas oriundas de sementes, não havendo limitação para a sua utilização comercial. A produção de mudas clonais de café é realizada em laboratórios de cultura de tecidos adaptados para a produção em escala industrial, denominados de biofábricas. Todavia, a produção de mudas clonais via embriogênese somática é uma técnica que ainda não foi explorada comercialmente no Brasil e não existe uma estimativa do custo de produção de mudas clonais de café arábica. Assim, o objetivo no presente trabalho foi calcular o custo de produção de mudas clonais de café em uma biofábrica de pequeno porte, tendo-se como base o protocolo desenvolvido pela Fundação Procafé/Embrapa Café, com a colaboração de pesquisadores da Embrapa Recursos Genéticos e Biotecnologia e do Centro de Cooperação Internacional em Pesquisa Agronômica para o Desenvolvimento, CIRAD, França. Este trabalho apresenta também uma relação dos equipamentos e materiais necessários para a produção de mudas de café in vitro. O custo de produção de uma muda foi de R1,34
INFLUÊNCIA DE MÉTODOS DE COLETA DE DADOS ESPECTRORRADIOMÉTRICOS SOB ÍNDICES DE VEGETAÇÃO EM EUCALIPTO
Objetivou-se verificar a influência de métodos de coleta de folhas em índices de vegetação: posição de coleta na copa, orientação cardeal e estação do ano em Eucalyptus grandis. Os dados foram coletados em dois povoamentos distintos em duas árvores dominantes cada. Foram coletadas 15 folhas em cada posição e em cada orientação, acrescidas de uma amostra de mesmo tamanho no centro. A coleta foi realizada em um único dia, das 13:00 as 15:00 horas. O material foi analisado com o espectrorradiômetro FieldSpec®3 e a resposta espectral de cada orientação e posição foi dada pela média da leitura espectral das folhas. Foram analisados 60 diferentes índices de vegetação de acordo com a literatura. Para avaliar o efeito da estação sobre os índices foram realizadas coletas nas quatro estações do ano, configurando 4 tratamentos. Foram utilizados modelos mistos para analisar a influência nos fatores (posição e estação) e sua interação. Os dados foram considerados aninhados em cada orientação, dentro de cada árvore e de cada área. A análise estatística foi realizada no software R com o pacote nlme. Dos índices de vegetação analisados, seis apresentaram dependência da posição/orientação e estação de coleta, sendo necessário em posteriores estudos a obediência de suas dependências
O IMPACTO DA MUDANÇA DO PROCESSO DE ENSINOAPRENDIZAGEM TRADICIONAL PARA A METODOLOGIA ATIVA: UM RELATO DE EXPERIÊNCIA
As Diretrizes Curriculares Nacionais propõe aos cursos de medicina um currículo baseado em competências, onde os conteúdos das ciências básicas e clinicas são desenvolvidos de forma integrada com os problemas de saúde da população, além de conter orientações para a adoção de metodologias de ensino centradas no aluno. Dessa forma, a Universidade do Grande Rio (Unigranrio) implementou em seu sistema de ensino os métodos ativos, uma concepção educativa na qual o estudante é o principal agente na construção do conhecimento, cabendo ao professor o papel de ativador/mediador no processo de ensino-aprendizagem.Sendo assim, o presente estudo do tipo relato de experiência teve como objetivos descrever a mudança do método tradicional de ensino para o ativo contemporâneo. Relatar a participação dos alunos no novo método e o compromisso do corpo docente na sua aplicação, além de descrever e caracterizar a metodologia ativa aplicada. Constatou-se que as principais modificações feitas, em comparação ao método tradicional de ensino, foram a utilização de casos clínicos através de uma adaptação do método do Arco de Charles Maguerez, a avaliação de imagens radiológicas e a utilização de peças anatômicas sintéticas. Alem disso, a análise histologia tornou-se informatizada mediante a utilização de programas. Foi também inaugurado o laboratório de vivencias, o que fez com que os acadêmicos despendessem muito mais tempo nas atividades práticas do que em sala de aula. Os investimentos feitos pela universidade, tanto em metodologia de ensino como em recursos, promoveram a curiosidade discente, o incentivo à autonomia e à interdisciplinaridade, o desenvolvimento do espírito de equipe e a aplicação prática da teoria
Nidification of Polybia rejecta (Hymenoptera: Vespidae) associated to Azteca chartifex (Hymenoptera: Formicidae) in a fragment of Atlantic Forest, in the state of Minas Gerais, southeastern Brazil
Out of Amazonia: Late Holocene Climate Change and the Tupi-Guarani Trans-Continental Expansion
This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordThe late Holocene expansion of the Tupi-Guarani languages from southern Amazonia to SE South America constitutes one of the largest expansions of any linguistic family in the world, spanning ~ 4000 km between latitudes 0°S and 35°S at about 2500 yr B.P. However, the underlying reasons for this expansion are a matter of debate. Here, we compare continental-scale paleoecological, paleoclimate, and archaeological datasets, to examine the role of climate change in facilitating the expansion of this forest-farming culture. Because this expansion lies within the path of the South American Low-Level Jet, the key mechanism for moisture transport across lowland South America, we were able to explore the relationship between climate change, forest expansion, and the Tupi-Guarani. Our data synthesis shows broad synchrony between late Holocene increasing precipitation and southerly expansion of both tropical forest and Guarani archaeological sites – the southernmost branch of the Tupi-Guarani. We conclude that climate change likely facilitated expansion of the Guarani forest-farming culture by increasing the area of forested landscape that they could exploit, showing a prime example of ecological opportunism.The ideas and themes developed in this paper stem from a European Research Council project ‘Pre-Columbian Amazon-Scale Transformations’ (ERC-CoG 616179) to JI. The University of Reading’s ‘Centre for Past Climate Change’ funded a writing workshop for this paper. RS was funded by an NERC ‘Scenario’ DTP PhD award. JGS was funded by a CAPES PhD scholarship (Ministry of Education, Brazil). JFC and MLC received postdoctoral funding from the University of Reading and the Arts and Humanities Research Council, respectively
Emergent quantum confinement at topological insulator surfaces
Bismuth-chalchogenides are model examples of three-dimensional topological
insulators. Their ideal bulk-truncated surface hosts a single spin-helical
surface state, which is the simplest possible surface electronic structure
allowed by their non-trivial topology. They are therefore widely
regarded ideal templates to realize the predicted exotic phenomena and
applications of this topological surface state. However, real surfaces of such
compounds, even if kept in ultra-high vacuum, rapidly develop a much more
complex electronic structure whose origin and properties have proved
controversial. Here, we demonstrate that a conceptually simple model,
implementing a semiconductor-like band bending in a parameter-free
tight-binding supercell calculation, can quantitatively explain the entire
measured hierarchy of electronic states. In combination with circular dichroism
in angle-resolved photoemission (ARPES) experiments, we further uncover a rich
three-dimensional spin texture of this surface electronic system, resulting
from the non-trivial topology of the bulk band structure. Moreover, our study
reveals how the full surface-bulk connectivity in topological insulators is
modified by quantum confinement.Comment: 9 pages, including supplementary information, 4+4 figures. A high
resolution version is available at
http://www.st-andrews.ac.uk/~pdk6/pub_files/TI_quant_conf_high_res.pd
Bringing Indigenous and Earth Sciences, Knowledges, and Practices Together to Understand and Respond to COVID-19
COVID-19 is having specific and devastating impacts, yet it is spurring resilient responses among Indigenous populations due to unique histories, cultures, geographies, and capacities. The Working Group on Indigenous and Earth Sciences Knowledges and Practices in Response to COVID-19 came together to foreground Indigenous perspectives in defining research questions for potential intercultural collaboration between Indigenous and Earth sciences to drive urgent, culturally relevant, and appropriate responses to COVID-19. The Working Group included intercultural, intergenerational, and interdisciplinary representatives from the Rising Voices Center for Indigenous and Earth Sciences, a nation-wide network of scientists, educators, students, and community leaders and organizers. To identify priority research areas and emerging questions, the Working Group hosted a webinar discussion and fielded a questionnaire with the Rising Voices community as well as utilized their own perspectives and expertise. The results highlighted four dynamics that many Indigenous Peoples are presently facing with the COVID-19 pandemic, including food security and safety; pre-existing conditions; turning to resilience and wisdom; and emerging questions at the nexus of Indigenous wisdom and knowledge and Earth sciences. Valuing Indigenous observations, knowledges, wisdom, and practices equally with Earth Sciences, this work contributes to decolonizing Earth Sciences, disaster management, and public health. It works to mitigate the particular threats and impacts that Indigenous communities and populations face from COVID-19 and the increasing spread of infectious diseases. Doing so addresses injustices in Earth Sciences and disaster management and the disproportionately adverse impacts of COVID-19 on Indigenous communities
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