Abstract:
:We present a review on two new tools to study biophysical properties of single molecules and single cells. A laser incident through a high numerical aperture microscope objective can trap small dielectric particles near the focus. This arrangement is named optical tweezers. This technique has the advantage to permit manipulation of a single individual object. We use optical tweezers to measure the entropic elasticity of a single DNA molecule and its interaction with the drug Psoralen. Optical tweezers are also used to hold a kidney cell MDCK away from the substrate to allow precise volume measurements of this single cell during an osmotic shock. This procedure allows us to obtain information about membrane water permeability and regulatory volume increase. Defocusing microscopy is a recent technique invented in our laboratory, which allows the observation of transparent objects, by simply defocusing the microscope in a controlled way. Our physical model of a defocused microscope shows that the image contrast observed in this case is proportional to the defocus distance and to the curvature of the transparent object. Defocusing microscopy is very useful to study motility and mechanical properties of cells. We show here the application of defocusing microscopy to measurements of macrophage surface fluctuations and their influence on phagocytosis.
journal_name
An Acad Bras Ciencjournal_title
Anais da Academia Brasileira de Cienciasauthors
Rocha MS,Mesquita ONdoi
10.1590/s0001-37652007000100003subject
Has Abstractpub_date
2007-03-01 00:00:00pages
17-28issue
1eissn
0001-3765issn
1678-2690pii
S0001-37652007000100003journal_volume
79pub_type
杂志文章abstract::Japanese Islands are covered with weathered volcanic rocks and soils. Terraced rice field are located in green-tuff areas which are very fertile but where landslides occur associated to strong earthquakes. The Xray diffraction and X-ray fluorescence analyses of the soils in landslide area identified predominant smecti...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652006000400010
更新日期:2006-12-01 00:00:00
abstract::Annulated thienopyrimidine derivatives attracted big interest of the scientific community due to their broad spectrum of biological activities among which are the inhibition of phosphodiesterase, antiproliferative and antimicrobial activities. As a continuation of our studies on the synthesis and biological activity o...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201820170798
更新日期:2018-04-23 00:00:00
abstract::In this paper, we prove that the dimension of the second space of reduced L2 cohomology of M is finite if is a complete noncompact hypersurface in a sphere ...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201620150085
更新日期:2016-10-01 00:00:00
abstract::The aim of this work was to investigate the phenolic content and antioxidant capacity of infusions of commercial herb samples (fennel, anise, peppermint, lemon grass and lemon balm) popularly consumed in Brazil. The infusion preparation for phenolic extraction was optimized using multivariate planning. Spectrophotomet...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765202020190646
更新日期:2020-11-11 00:00:00
abstract::We describe a dentary of a new titanosaur sauropod, Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina. The material comes from the Portezuelo Formation, Neuquén Group. Titanosaur sauropods lower jaws are scarce and only nine taxa with dentaries have been described. There are two t...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201820180661
更新日期:2019-01-01 00:00:00
abstract::Agapanthus (Agapanthaceae) has 10 species described. However, most taxonomists differ respect to this number because the great phenotypic plasticity of the species. The cytogenetic has been an important tool to aid the plant taxon identification, and to date, all taxa of Agapanthus L'Héritier studied cytologically, pr...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201620150514
更新日期:2016-01-01 00:00:00
abstract::This work describes the chemical composition and antimicrobial activity of the volatile oils of Ocimum canum and Ocimum selloi, both occurring in Jequié/BA, northeastern Brazil. The plants were collected in the winter/2005 and summer/2006, the oils extracted by steam distillation and further analyzed by GC-MS. A total...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652011005000019
更新日期:2011-09-01 00:00:00
abstract::Cariniana rubra Miers (Lecythidaceae), popularly known as "jequitibá-vermelho'', is a large Brazilian tree whose bark is used in infusion and decoction for the treatment of inflammatory conditions. This study aims to assess the anti-inflammatory, antinociceptive, and antipyretic effects of Cariniana rubra methanolic s...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652011005000006
更新日期:2011-06-01 00:00:00
abstract::This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652011000400019
更新日期:2011-12-01 00:00:00
abstract::Fruits are rich in minerals, which are essential for a wide variety of metabolic and physiologic processes in the human body. The use of frozen fruits has greatly spread in the last years not only in the preparation of juices, but also as raw material for yogurts, candies, cookies, cakes, ice creams, and children's fo...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652010000400008
更新日期:2010-12-01 00:00:00
abstract:UNLABELLED:Thirty-five patients (23 males and 12 females), age 35 +/- 13 years old, presenting either idiopathic calcium nephrolithiasis, nephrocalcinosis or mild renal failure with idiopathic calcium nephrolithiasis were selected for the analysis of low molecular weight proteinuria and the possible mutations occurrenc...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652005000100007
更新日期:2005-03-01 00:00:00
abstract::Helicoverpa gelotopoeon is an endemic pest of South America that affects soybean and other important crops. Life tables are a fundamental tool used to study insect populations, resulting in crucial information for integrated pest management programs. Therefore, the aim of this study was to evaluate the biotic potentia...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201820180318
更新日期:2018-10-01 00:00:00
abstract::Analogue experiments were carried out to get insights into the processes governing positive inversion during the foreland propagating thrust tectonics in the southern Serra do Espinhaço, a Brasiliano/Panafrican foldthrust belt in southeast Brazil. In particular, model listric half-grabens were inverted by applying con...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652006000200012
更新日期:2006-06-01 00:00:00
abstract::This study investigated the effects of stocking density and dietary supplementation of probiotic (Lactobacillus) on growth, traits of carcass, lymphoid organs and intestinal microbial count of Japanese quail. Quail chicks (one week old) were randomly allotted to 6 groups in a 2×3 factorial experiment included 2 levels...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201920180616
更新日期:2019-01-01 00:00:00
abstract::Rotifers have often been used as indicators of sudden changes in physical and chemical features of the aquatic environment. Such features vary greatly during flood pulse events in small lakes connected to major floodplains. However, few are the studies that investigate the consequences of the flood pulse in rotifer sp...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201420130323
更新日期:2014-09-01 00:00:00
abstract::Specimens of Leptogium collected in ten localities from the State of Rio Grande do Sul were studied. Sixteen species were found of 28 records mentioned to the state, which represents around 57% of the Leptogium diversity known for Rio Grande do Sul. Leptogium exaratum is proposed as a new species. Leptogium atlanticum...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201920180313
更新日期:2019-02-14 00:00:00
abstract::Eimeriosis is caused by a protozoan parasite of the genus Eimeria and infection affecting most domestic animal species. The aim of this research was to comprehend the impact of selenium nanoparticles (SeNPs) on eimeriosis induced by Eimeria papillata in mouse jejunum, and how they work as antioxidants and anti-apoptot...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765202020191107
更新日期:2020-06-03 00:00:00
abstract::The Jequiezinho River is a temporary river. In the urban stretch it is impacted, with perennial flow coming from domestic sewage and rainwater. This study evaluated the geochemical distribution and potential mobility of some metals (Pb, Co, Ca, Cr, Mg, Cu, Fe, Mn, Ni and Zn) in sediments of the Jequiezinho River. Sedi...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765202020190558
更新日期:2020-11-27 00:00:00
abstract::We investigated the influence of environmental factors in spatial and temporal distribution of the seabob shrimp Xiphopenaeus kroyeri in Santos Bay and São Vicente Estuary, state of São Paulo, Brazil. Monthly samples were obtained, from May 2008 through April 2010, from four locations in the estuary and four in the ba...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201420130230
更新日期:2014-09-01 00:00:00
abstract::This study presents the bioreduction of six β-ketoesters by whole cells of Kluyveromyces marxianus and molecular investigation of a series of 13 β-ketoesters by hologram quantitative structure-activity relationship (HQSAR) in order to relate with conversion and enantiomeric excess of β-stereogenic-hydroxyesters obtain...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201720170118
更新日期:2017-07-01 00:00:00
abstract::Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal bacteria and antioxidant properties. Eugenia klotzschiana Berg (pêra-do-cerrado, in Portuguese) is a species of Myrtaceae with restricted distribution in the Cerrado. The essential oils were extracted through the h...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201720160652
更新日期:2017-07-01 00:00:00
abstract::In some previous studies, we described the isolation of nine compounds from leaves of Derris urucu, a species found widely in the Amazon rainforest, identified as five stilbenes and four dihydroflavonols. In this work, three of these dihydroflavonols [urucuol A (1), urucuol B (2) and isotirumalin (3)] were evaluated t...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/S0001-37652013000300004
更新日期:2013-09-01 00:00:00
abstract::Pterosaurs possess skeletal pneumatization, which can be assessed externally through the observation of pneumatic foramina. These foramina vary in position, shape, and number among taxa. Here we propose new characters referring to the position and number of pneumatic foramina present in cervical and dorsal vertebrae o...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201920180782
更新日期:2019-01-01 00:00:00
abstract::Programs of Science and Technology research have grown significantly in Brazil over the last decades. Until the 1980s the so-called undirected programs, without specific goals and requiring only scientific merit, prevailed. The few programs with defined goals in this period were never objectively assessed. The same si...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652007000300014
更新日期:2007-09-01 00:00:00
abstract::This study presents paleoenvironmental data based on pollen, elemental and isotopic compositions of organic matter (TOC, N, δ(13)C and δ(15)N) and (14)C dating of 170 cm lake sediment record. Samplings have been made in Lagoa Grande at Parque Estadual Turístico do Alto Ribeira - PETAR, Southern São Paulo State, Southe...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652010000300019
更新日期:2010-09-01 00:00:00
abstract::Most herbicides applied in crop field, stay in the soil for a period, affecting next crop or even the plants using as green manure. Nowadays, the use of herbicides grow to increase productivity, mainly in the grain producing region north of Rio Grande do Sul state. The objective of this study was to evaluate the effec...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201820170482
更新日期:2018-04-01 00:00:00
abstract::Intensification of aquaculture production systems exposes fish to numerous stressors, which may negatively affect their growth and limit profitability of aquaculture systems. This study determined effects of increasing levels of dietary mannanoligosaccharides on growth and intestine morphology of pacu. Fish (44.04 g) ...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201420130088
更新日期:2014-09-01 00:00:00
abstract::A new azhdarchoid pterosaur from the Upper Cretaceous of Patagonia is described. The material consists of an incomplete edentulous lower jaw that was collected from the upper portion of the Portezuelo Formation (Turonian-Early Coniacian) at the Futalognko site, northwest of Neuquén city, Argentina. The overall morphol...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201720170478
更新日期:2017-01-01 00:00:00
abstract::Current two-dimensional (2D) ultrasonic marker measurements are inherent with intra- and inter-observer variability limitations. The objective of this paper is to investigate the performance of conventional 2D ultrasonic marker measurements and proposed programmable interactive three-dimensional (3D) marker evaluation...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/s0001-37652012000400030
更新日期:2012-12-01 00:00:00
abstract::Citrus aurantium L., commonly known as bitter orange, is widely used in folk medicine, but there is little data in the literature about the effects on pregnancy. The aim of the present study was to evaluate the influence of essential oil obtained from fruits of Citrus aurantium on the maternal reproductive outcome and...
journal_title:Anais da Academia Brasileira de Ciencias
pub_type: 杂志文章
doi:10.1590/0001-3765201520140354
更新日期:2015-03-01 00:00:00