Experimental nodel of C6 brain tumors in athymic rats

Malignant brain tumor experimental models tend to employ cells that are immunologically compatible with the receptor animal. In this study, we have proposed an experimental model of encephalic tumor development by injecting C6 cells into athymic Rowett rats, aiming at reaching a model which more closely resembles to the human glioma tumor. In our model, we observed micro-infiltration of tumor cell clusters in the vicinity of the main tumor mass, and of more distal isolated tumor cells immersed in normal encephalic parenchyma. This degree of infiltration is superior to that usually observed in other C6 models.

Search for cytotoxic agents in multiple Laurencia complex seaweed species (Ceramiales, Rhodophyta) harvested from the Atlantic Ocean with emphasis on the Brazilian State of Espírito Santo

The development of new anti-cancer drugs of algal origin represents one of the least explored frontiers in medicinal chemistry. In this regard, the diversity of micro- and macroalgae found in Brazilian coastal waters can be viewed as a largely untapped natural resource. In this report, we describe a comparative study on the cytotoxic properties of extracts obtained from the Laurencia complex: Laurencia aldingensis, L. catarinensis, L. dendroidea, L. intricata, L. translucida, L. sp, and Palisada flagellifera. All of these species were collected in the coastal waters of the State of Espírito Santo, Brazil. Four out of the twelve samples initially investigated were found to show significant levels of toxicity towards a model tumor cell line (human uterine sarcoma, MES-SA). The highest levels of cytotoxicity were typically associated with non-polar (hexane) algal extracts, while the lowest levels of cytotoxicity were found with the corresponding polar (methanol) extracts. In this report, we also describe a biological model currently in development that will not only facilitate the search for new anti-cancer drug candidates of algal origin, but also permit the identification of compounds capable of inducing the destruction of multi-drug resistant tumors with greater efficiency than the pharmaceuticals currently in clinical use.

Non-coding RNAs in schistosomes: an unexplored world

Non-coding RNAs (ncRNAs) were recently given much higher attention due to technical advances in sequencing which expanded the characterization of transcriptomes in different organisms. ncRNAs have different lengths (22 nt to >1, 000 nt) and mechanisms of action that essentially comprise a sophisticated gene expression regulation network. Recent publication of schistosome genomes and transcriptomes has increased the description and characterization of a large number of parasite genes. Here we review the number of predicted genes and the coverage of genomic bases in face of the public ESTs dataset available, including a critical appraisal of the evidence and characterization of ncRNAs in schistosomes. We show expression data for ncRNAs in Schistosoma mansoni. We analyze three different microarray experiment datasets: (1) adult worms' large-scale expression measurements; (2) differentially expressed S. mansoni genes regulated by a human cytokine (TNF-α) in a parasite culture; and (3) a stage-specific expression of ncRNAs. All these data point to ncRNAs involved in different biological processes and physiological responses that suggest functionality of these new players in the parasite's biology. Exploring this world is a challenge for the scientists under a new molecular perspective of host-parasite interactions and parasite development.

A análise por injeção sequencial (SIA): vinte anos em uma perspectiva brasileira

The year of 2010 marks the 20th anniversary of the development of Sequential Injection Analysis (SIA) by Ruzicka and Marshall. Considered the second generation of the flow injection methods, this article briefly describes the history, the basic principles of the technique and reviews all papers developed by Brazilian scientists aiming the divulgation of this automation technique in Analytical Chemistry.

Métodos para fabricação de microeletrodos visando a detecção em microambientes

Analysis at microenvironments, like single cells or in minute volumes (nL), is an area of great interest for analytical and biological sciences. Measurements at these experimental conditions demand analytical tools (microelectrodes) capable of monitoring with rapid response, good resolution and minimal perturbation of the system. The major drawbacks in producing these microscopic electrodes have been largely overcome, principally due to the development of new fabrication methods. In this review, these procedures are described with emphasis to those devoted to the construction of microelectrodes for application in microenvironments. Examples of our efforts to use these devices as effective electrochemical sensors are also addressed.

Rheology of decane/water and triglyceride/water emulsions stabilized by β-casein and sodium caseinate

β-Casein and sodium caseinate stabilized emulsions were produced and had their rheological properties investigated as a function of the nature of the oil phase, ionic strength and pH. Oil phases of distinct structural characteristics, namely decane and vegetable oil of high triglyceride content, were assayed. The former was much more effectively emulsified than the latter. Effects of pH and ionic strength were minor. Emulsion rheological properties were strikingly distinct in each case, with viscoelastic, solid-like structures being formed with decane (G' >> G"), differently from what is observed for samples containing triglycerides as the oil phase, in which viscoelasticity was not even apparent. The relevance of the spatial features of the oil phase structure in the development of the emulsion viscoelastic character is discussed. Factors responding for the system distinct behaviour possibly reside at the emulsion droplet interface, unapproachable by optical microscopy, rather than on aspects related to particle size or shape.

Nanochromics: old materials, new structures and architectures for high performance devices

Due to the development of nanoscience, the interest in electrochromism has increased and new assemblies of electrochromic materials at nanoscale leading to higher efficiencies and chromatic contrasts, low switching times and the possibility of color tuning have been developed. These advantages are reached due to the extensive surface area found in nanomaterials and the large amount of organic electrochromic molecules that can be easily attached onto inorganic nanoparticles, as TiO2 or SiO2. Moreover, the direct contact between electrolyte and nanomaterials produces high ionic transfer rates, leading to fast charge compensation, which is essential for high performance electrochromic electrodes. Recently, the layer-by-layer technique was presented as an interesting way to produce different architectures by the combination of both electrochromic nanoparticles and polymers. The present paper shows some of the newest insights into nanochromic science.

A biosensor based on immobilization of lactate oxidase in a PB-CTAB film for FIA determination of lactate in beer samples

An amperometric lactate biosensor with lactate oxidase immobilized into a Prussian Blue (PB) modified electrode was fabricated. The advantage of using cetyltrimethylammonium bromide (CTAB) in the electrodeposition step of PB films onto glassy carbon surfaces was confirmed taking into account both the stability and sensitivity of the measurements. The biosensor was used in the development of a FIA amperometric method for the determination of lactate. Under optimal operating conditions (pH = 6.9, E = -0.1 V), the linear response of the method was extended up to 0.28 µmol L-1 lactate with a limit of detection of 0.84 mmol L-1. The repeatability of the method for injections of a 0.28 mmol L-1 lactate solution was 2.2 % (n = 18). The usefulness of the method was demonstrated by determining lactate in beer samples and the results were in good agreement with those obtained by using a reference spectrophotometric enzyme method.

A Equação-Mestra: atingindo o equilíbrio

In the last years, a great interest in nonequilibrium systems has been witnessed. Although the Master Equations are one of the most common methods used to describe these systems, the literature about these equations is not straightforward due to the mathematical framework used in their derivations. The goals of this work are to present the physical concepts behind the Master Equations development and to discuss their basic proprieties via a matrix approach. It is also shown how the Master Equations can be used to model typical nonequilibrium processes like multi-wells chemical reactions and radiation absorption processes.

Nursery performance of the pink shrimp Farfantepenaeus paulensis (Crustacea: Decapoda: Penaeidae) postlarvae in different salinities

Nursery performance, development, and RNA:DNA ratio were investigated in Farfantepenaeus paulensis (Pérez-Farfante, 1967) postlarvae acclimated from a salinity of 30‰ to higher (35‰) or lower (16, 22 and 29‰) salinities and reared for 20 days. Overall, higher final weight, yield and growth rate were observed at a salinity of 29‰. RNA:DNA ratio indicated reduced growth potential at a salinity of 35‰. Low salinities resulted in more developed individuals. Thus, early postlarval F. paulensis should not be stocked in salinities higher than that of the original hatchery, otherwise in lower salinities postlarvae should be older and/or have an extended nursery phase. Results may assist in the development of nursery rearing protocols for F. paulensis, an alternative species for aquaculture in subtropical areas.

Desenvolvimento dos ovários da lagosta Panulirus echinatus (Crustacea: Palinuridae) baseados nas análises macroscópica, microscópica e relação gonadossomática (RGS)

Os estádios de desenvolvimento dos ovários da lagosta Panulirus echinatus Smith, 1869 foram caracterizados com base nos aspectos macroscópicos, microscópicos e na relação gonadossomática (RGS). Através de amostragem mensal (novembro/1999 a outubro/2000) foram capturadas 711 fêmeas, empregando-se redes de espera de fundo. Retirou-se a região dorsal da carapaça para avaliação dos ovários. Estes foram dissecados, pesados, fixados em solução de Bouin e submetidos aos procedimentos histológicos. A análise microscópica dos ovários foi avaliada pela presença de células germinativas nas diferentes fases de desenvolvimento. Esta análise quando associada a macroscopia (mudança de cor e volume das gônadas no cefalotórax) e a relação gonadossomática (RGS) possibilitou a caracterização de cinco estádios de desenvolvimento: imaturo (I), em desenvolvimento (II), pré-maturação (III), maduro (IV) e pós-desova (V). As análises estatísticas confirmaram que a RGS pode ser utilizada como indicadora dos estádios de maturidade.

Massa das sementes de Tecoma stans L. Juss. ex Kunth (Bignoniaceae): efeitos na emergência e desenvolvimento de suas plântulas no sol e na sombra

The aim of this study was to evaluate the effect of Tecoma stans L. Juss. ex Kunth seeds mass on initial emergence, growth and, seedling development under different light conditions. The seeds were separated in four mass classes and sowed in four replicates of 24 seeds for each class, under full sun and canopy shade. Under sun environment was observed a greater percentage of emergence. Heavy seeds presented the greater percentage of emergence under both environments, but a greater rate was observed under canopy shade. One month after the start of experiments, the seedlings at the shade environment presented 100% of mortality. The growth and development seedlings under full sun were noticed for five months. In this period, only in the first three months was possible to observe the effects of Tecoma stans seeds mass on capacity of seedlings to acquire dry mass. The seedlings biomass partitions were similar among the tested mass class. The seedlings of smaller mass tended to a high specific leaf area in relation to the seedlings from large seeds, mainly in the first three months, resulting in a great acquisition of dry mass by these seedlings. In the fourth month, the specific leaf area did not present any tendency. Because the biggest seeds to give rise seedlings with best initial development than smallest seeds can be considered as species reproductive strategy. To produce seeds of different sizes also can be considered as way of species to spread in many microhabitats.

Estádios de desenvolvimento dos órgãos reprodutivos dos machos de Panulirus echinatus Smith (Decapoda: Palinuridae)

Esta pesquisa caracteriza os estádios de desenvolvimento dos testículos e canais deferentes da lagosta Panulirus echinatus Smith, 1869 a partir da relação entre seus aspectos macroscópicos, microscópicos e a relação gonadossomática (RGS). Através de amostragem mensal (novembro de 1999 a outubro de 2000) foram capturados 1716 machos, empregando-se redes de espera de fundo. Retirou-se a região dorsal da carapaça para avaliação dos órgãos reprodutivos. Os testículos e canais deferentes foram dissecados, pesados, fixados em solução de Bouin e submetidos aos procedimentos histológicos. A análise microscópica dos órgãos reprodutivos foi avaliada pela presença ou ausência de espermatozóides nos testículos e canais deferentes. Esta, quando associada a macroscopia (mudança de cor, tamanho, diâmetro e desenvolvimento de espermatóforo) e a relação gonadossomática (RGS), possibilitou a caracterização de três estádios de desenvolvimento: imaturo, intermediário e maturo. Ficou evidenciada que a maturidade dos testículos precedeu a maturidade dos canais deferentes. Para avaliar se a RGS é um bom indicador quantitativo dos estádios de maturidade, um teste t (alfa = 0,05) foi usado e constatou diferença significativa nas médias da RGS. A RGS pode ser utilizada como indicadora dos estádios de maturidade para P. echinatus.

The influence of the 1992-1993 el niño on the reproductive biology of Scomber japonicus peruanus (Jordán & Hubb, 1925)

The influence of the 1992-1993 El Niño events on the reproductive behavior of the Scomber japonicus peruanus (Chub mackerel) was studied from samples collected monthly, along the Peruvian coast (3º23'S-14º00'S), from January 1990 to December 1993. The monthly variation of the gonadosomatic index and the frequency of the periods of gonad maturation evidenced that the spawning of the species occurred all year long, being more intense in summer. The values of the gonadosomatic index were higher during the occurrence of the 1992-1993 El Niño, while the body weight and gonad weight decreased. Regarding the condition factor, its values decreased in females over 35 cm in fork length.

Analysis of mangrove forest succession, using sediment cores: a case study in the Cananéia -Iguape coastal system, São Paulo Brazil

Sediment cores are an essential tool for the analysis of the dynamics of mangrove succession. Coring was used to correlate changes in depositional environments and lateral sedimentary facies with discrete stages of forest succession at the Cananéia-Iguape Coastal System in southeastern Brazil. A local level successional pattern was examined based on four core series T1) a sediment bank; T2) a smooth cordgrass Spartina alterniflora bank; T3) an active mangrove progradation fringe dominated by Laguncularia racemosa, and; T4) a mature mangrove forest dominated by Avicennia schaueriana. Cores were macroscopically described in terms of color, texture, sedimentary structure and organic components. The base of all cores exhibited a similar pattern suggesting common vertical progressive changes in depositional conditions and subsequent successional colonization pattern throughout the forest. The progradation zone is an exposed bank, colonized by S. alterniflora. L. racemosa, replaces S. alterniflora as progradation takes place. As the substrate consolidates A. schaueriana replaces L. racemosa and attains the greatest structural development in the mature forest. Cores collected within the A. schaueriana dominated stand contained S. alterniflora fragments near the base, confirming that a smooth cordgrass habitat characterized the establishment and early seral stages. Cores provide a reliable approach to describe local-level successional sequences in dynamic settings subject to drivers operating on multiple temporal and spatial scales where spatial heterogeneity can lead to multiple equilibria and where similar successional end-points may be reached through convergent paths.