Evaluation of uranium incorporation from contaminated areas using teeth as bioindicators - a case study

The Southwest region of the Bahia state in Brazil hosts the largest uranium reserve of the country (100 kton in uranium, only), plus the cities of Caetite, Lagoa Real and Igapora. In this work, aim was at the investigation of uranium burdens on residents of these cities by using teeth as bioindicators, as a contribution for possible radiation protection measures. Thus, a total of 41 human teeth were collected, plus 50 from an allegedly uranium free area (the control region). Concentrations of uranium in teeth from residents of 5- to 87-y old were determined by means of a high-resolution inductively coupled plasma mass spectrometer (ICP-MS). The highest uranium concentration in teeth was measured from samples belonging to residents of Caetite (median equal to 16 ppb). Assuming that the uranium concentrations in teeth and bones are similar within 10-20% (for children and young adults), it concluded that uranium body levels in residents of Caetite are at least one order of magnitude higher than the worldwide average. This finding led to conclude that daily ingestion of uranium, from food and water, is equally high.

Avaliação do estresse oxidativo induzido por superfícies de titânio

Commercially pure Titanium (cp Ti) is a material largely used in orthopedic and dental implants due to its biocompatibility properties. Changes in the surface of cp Ti can determine the functional response of the cells such as facilitating implant fixation and stabilization, and increased roughness of the surface has been shown to improve adhesion and cellular proliferation. Various surface modification methods have been developed to increase roughness, such as mechanical, chemical, electrochemical and plasma treatment. An argon plasma treatment generates a surface that has good mechanical proprieties without chemical composition modification. Besides the topography, biological responses to the implant contribute significantly to its success. Oxidative stress induced by the biomaterials is considered one of the major causes of implant failure. For this reason the oxidative potential of titanium surfaces subjected to plasma treatment was evaluated on this work. CHO-k1 cells were cultivated on smooth or roughed Ti disks, and after three days, the redox balance was investigated measuring reactive oxygen species (ROS) generation, total antioxidant capacity and biomarkers of ROS attack. The results showed cells grown on titanium surfaces are subjected to intracellular oxidative stress due to hydrogen peroxide generation. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular ability. Our data suggest that plasma treated titanium may be a more biocompatible biomaterial.

Adesão, proliferação e genotoxicidade celular de celulose bacteriana modificada por plasma

Bacterial cellulose (BC) has a wide range of potential applications, namely as temporary substitute skin in the treatment of skin wounds, such as burns, ulcers and grafts. Surface properties determine the functional response of cells, an important factor for the successful development of biomaterials. This work evaluates the influence of bacterial cellulose surface treatment by plasma (BCP) on the cellular behavior and its genotoxicity potential. The modified surface was produced by plasma discharge in N2 and O2 atmosphere, and the roughness produced by ion bombardment characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Cell adhesion, viability and proliferation on BCP were analysed using crystal violet staining and the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium (MTT) method. Genotoxicity was evaluated using the comet and cytokinesis block micronucleus assay. The results show that the plasma treatment changed surface roughness, producing an ideal cell attachment, evidenced by more elongated cell morphology and improved proliferation. The excellent biocompatibility of BCP was confirmed by genotoxicity tests, which showed no significant DNA damage. The BCP has therefore great potential as a new artificial implant

Digestibility for dogs and cats of meat and bone meal processed at two different temperature and pressure levels

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Respostas funcionais de diferentes tamanhos de Tilápia do Nilo; Oreochromis niloticus; predando zooplâncton

The Nile tilapia, Oreochromis niloticus, is an important omnivorous fish in the reservoirs of the semi-arid region of Brazil. Throughout its growth tilapia s feeding behavior changes from a visual predator of zooplankton to a filter-feeder, collecting suspended particulate matter, including planktonic organisms, through pumping. This feature results in different impacts of tilapia on plankton community as the fish grows. Aiming to quantify the functional response of different sizes of Nile tilapia on zooplankton experiments in microcosms scale in the laboratory and in mesocosm scale in the field were carried out. The data were fitted to four different models of functional response. The best fits were obtained for nonlinear models in laboratory experiments. While the experiments in mesocosms were the best settings for responses of type I (juvenile and adult tilapia) and type III (fry). The Manly's alpha index was used to evaluate the feeding selectivity of tilapia on the three main groups of the zooplankton in the experiments in mesocosms. The results show that: (i) rotifers were the preferred prey of fingerlings,(ii) copepods were rejected by fry and juvenile tilapia and (iii) adult fish fed non-selectively on copepods, cladocerans and rotifers. The functional response models obtained in this research can be applied to population models and help in modeling the dynamics of interactions between Nile tilapia and the planktonic communities in the reservoirs of the semi-arid

Biologia de Agistemus brasiliensis Matioli, Ueckermann & Oliveira (Acari: Stigmaeidae) e sua potencialidade de predação sobre Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tempo de busca e de manuseio de larvas de Chrysoperla externa (Hagen, 1861) (Neuroptera, Chrysopidae) alimentadas com Uroleucon ambrosiae (Thomas, 1878) (Hemiptera, Aphididae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of three protocols for superovulation of brown brocket deer (Mazama gouazoubira)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The effect of refuge on Dermestes ater (Coleoptera : Dermestidae) predation on Musca domestica (Diptera : Muscidae): Refuge for prey or the predator?

It is believed that habitat heterogeneity can change the extent of predator-prey interactions. Therefore, in this study we examined the effect of habitat heterogeneity (characterized here as an addition of refuge) on D. ater predation on M. domestica. Predation of D. ater on M. domestica larvae was carried out in experimental habitats with and without refuge, and examined at different prey densities. The number of prey eaten by beetles over 24 h of predator-prey interaction was recorded, and we investigated the strength of interaction between prey and predator in both experimental habitats by determining predator functional response. The mean number of prey eaten by beetles in the presence of refuge was significantly higher than in the absence of refuge. Females had greater weight gains than males. Logistic regression analyses revealed the type II functional response for both experimental habitats, even though data did not fit well into the random predator model. Results suggest that the addition of refuge in fact enhanced predation, as prey consumption increased in the presence of refuge. Predators kept in the presence of refuge also consumed more prey at high prey densities. Thus, we concluded that the addition of refuge was an important component mediating D. ater-M. domestica population interactions. Refuge actually acted as a refuge for predators from prey, since prey behaviors detrimental to predators were reduced in this case.

Metabolic changes in Brycon cephalus (Teleostei, Characidae) during post-feeding and fasting

Metabolic changes during the transition from post-feeding to fasting were studied in Brycon cephalus, an omnivorous teleost from the Amazon Basin in Brazil. Body weight and somatic indices (liver and digestive tract), glycogen and glucose content in liver and muscle, as well as plasma glucose, free fatty acids (FFA), insulin and glucagon levels of B. cephalus, were measured at 0, 12, 24, 48, 72, 120, 168 and 336 h after the last feeding. At time 0 h (the moment of food administration, 09.00 h) plasma levels of insulin and glucagon were already high, and relatively high values were maintained until 24 h post-feeding. Glycemia was 6.42 +/- 0.82 mM immediately after food ingestion and 7.53 +/- 1.12 MM at 12 h. Simultaneously, a postprandial replenishment of liver and muscle glycogen reserves was observed. Subsequently, a sharp decrease of plasma insulin occurred, from 7.19 +/- 0.83 ng/ml at 24 h of fasting to 5.27 +/- 0.58 ng/ml at 48 h. This decrease coincided with the drop in liver glucose and liver glycogen, which reached the lowest value at 72 h of fasting (328.56 +/- 192.13 and 70.33 +/- 14.13 mumol/g, respectively). Liver glucose increased after 120 h and reached a peak 168 h post-feeding, which suggests that hepatic gluconeogenesis is occurring. Plasma FFA levels were low after 120 and 168 h and increased again at 336 h of fasting. During the transition from post-feeding to fast condition in B. cephalus, the balance between circulating insulin and glucagon quickly adjust its metabolism to the ingestion or deprivation of food. (C) 2002 Elsevier B.V. All rights reserved.

Disturbance chemical cues determine changes in spatial occupation by the convict cichlid Archocentrus nigrofasciatus

I studied the effect of disturbance chemical cues on fish that make trade-offs between foraging in an open area and remaining in a safe refuge. I used convict cichlids Archocentrus nigrofasciatus that were either visually exposed to a predator (n = 8) or exposed to water conditioned by chemical cues from disturbed conspecifics (n = 8). Fish visually exposed to a predator decreased their ingestion rate and spent more time in the refuge than in the foraging area, while fish receiving water from frightened conspecifics did not alter their ingestion rate or time spent in the refuge and foraging site, but increased their spatial occupation (i.e., motion). These results suggest that convict cichlids recognized the predator by visual cues. Moreover, disturbance cues are a form of threatening public information that may increase fish spatial occupation due to increased exploring behaviour; but is not sufficiently alarming to alter feeding or increase refuge use. (C) 2004 Elsevier B.V. All rights reserved.

Compartilhamento de recursos por duas espécies de peixes nectobentônicas de riachos na bacia do rio Cachoeira (BA)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diet of fishes in Passa Cinco stream, Corumbataí River sub-basin, São Paulo state, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analyses of the genotoxic and mutagenic potential of the products formed after the biotransformation of the azo dye Disperse Red 1

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ingestão de ração e comportamento de larvas de pacu em resposta a estímulos químicos e visuais

Este estudo foi realizado com o objetivo de comparar a influência dos estímulos visual e/ou químico de náuplios de Artemia e de dieta microencapsulada sobre a taxa de ingestão da dieta microencapusulada por larvas de pacu Piaractus mesopotamicus. Utilizou-se um esquema fatorial 7 x 4 (estímulos e idades) com duas repetições. Verificou-se efeito da idade das larvas e dos estímulos, mas não houve efeito para a interação idade ´ estímulos. O estímulo químico da Artemia e ambos os estímulos da Artemia resultaram em maior taxa de ingestão de dieta inerte. Resultado intermediário foi obtido com o estímulo visual da dieta microencapsulada. O estímulo químico, em comparação ao estímulo visual da Artemia, resultou em maiores taxas de ingestão da dieta. Com o aumento da idade, houve incremento na taxa de ingestão. Os estímulos visual e químico dos náuplios e o estímulo visual da ração aumentaram a ingestão de dieta inerte por larvas de pacu. Náuplios de Artemia devem ser oferecidos antes do fornecimento da dieta inerte, pois podem auxiliar no processo de transição alimentar. Os resultados deste trabalho apontaram novas possibilidades de estudos com larvas de peixes neotropicais visando a substituição precoce do alimento vivo para o inerte.