Nesting ecology of Podocnemis expansa (Schweigger, 1812) and Podocnemis unifilis (Troschel, 1848) (Testudines, Podocnemididae) in the Javaés River, Brazil [Ecologia reprodutiva de Podocnemis expansa (Schweigger, 1812) e Podocnemis unifilis (Troschel, 1848) (Testudines, Podocnemididae) no Rio Javaés, Brasil]
Ferreira Jr. P.D.,Centro Universitario Vila Velha |
Castro P.T.A.,Federal University of Ouro Preto
Brazilian Journal of Biology | Year: 2010
Nest site has influence on incubation duration and hatching success of two Neotropical turtles, the Giant Amazon River Turtle (Podocnemis expansa) and Yellow-Spotted Side-Neck Turtle (Podocnemis unifilis - "Tracajá"). The 2000 and 2001 nesting seasons have been monitored at the Javaés River in Bananal Island, Brazil. Although they nest on the same beaches, there is a separation of the nesting areas of P unifilis and P. expansa nests on the upper parts of the beach. The incubation duration for P. expansa is influenced by the nesting period, the height of the nest from the river, the clutch size, and the grain size in the site of the nest. Nests of Podocnemis expansa placed in coarse sediments have shorter incubation duration than those placed in finer sediments. The hatching success in P. expansa is influenced by grain size, incubation duration, and nesting period. The grain size is negatively correlated with hatching success, indicating that the nests situated in finer-grained sand have better chances of successful egg hatching than those in coarser-grained sand. Nests of the end of the reproductive season have lower hatching success and incubation duration than those at the start of the season. For P. unifilis, the nesting period and nest depth influence the incubation duration; moreover, the river dynamics significantly affect the hatching success. The oscillation of the river level and the moment of initial increase, the height of the nest from the river level, and the nesting period are all decisive components for hatching success. The results of this research show the importance of protecting areas with great geological diversity, wherein the features of the environment can affect the microenvironment of nests, with consequences on incubation duration and hatching success.
Duca C.,University of Brasilia |
Duca C.,Centro Universitario Vila Velha |
Marini M.A.,University of Brasilia
Wilson Journal of Ornithology | Year: 2011
The Shrike-like Tanager (Neothraupis fasciata) is a Cerrado bird considered as near threatened. Its life history is poorly known, especially its reproduction. We monitored reproduction during four breeding seasons (2003-2006) with 120 nests in a protected area in central Brazil. Nesting began at the end of the dry season and start of the rainy season. The incubation (13.0 days) and nestling (11.7 days) periods were shorter than for most neotropical birds, but similar to some other tanagers. Clutch size (2-3 eggs) was similar to most tropical birds. However, clutch size increased and nest initiation date advanced ∼30 days in a year of early precipitation compared to 3 other years with regular or late precipitation. The Shrike-like Tanager had breeding flexibility and ability to adapt to changes in temporal precipitation patterns. © 2011 by the Wilson Ornithological Society.
Schneider S.,Albert Ludwigs University of Freiburg |
Lenz D.,Centro Universitario Vila Velha |
Holzer M.,Albert Ludwigs University of Freiburg |
Palme K.,Albert Ludwigs University of Freiburg |
Suss R.,Albert Ludwigs University of Freiburg
Journal of Controlled Release | Year: 2010
Gene therapy is a promising therapeutic concept for a large number of incurable diseases. Lipid/DNA complexes (lipoplexes) are used to deliver genes into cells. However, while large efforts have been made to investigate the fate of lipoplexes once inside the cell, the rate of intracellular dissociation is still largely unknown. Analysis of the dissociation rates of DNA from lipid/DNA complexes is crucial for the evaluation of a gene delivery system's efficiency. This study introduces a new fluorescence resonance energy transfer (FRET) approach for the intracellular dissociation analysis of lipid/DNA complexes. Here, the labeling of both complex components, DNA as well as lipid, reveals whether DNA is still associated with the lipid or has dissociated. In this study the kinetic properties of complex dissociation were consistently measured with flow cytometry and fluorescence microscopy, and indicated that most complexes were dissociated after 24. h in A-10 cells. © 2010 Elsevier B.V.
Ligeiro R.,Federal University of Minas Gerais |
Moretti M.S.,Federal University of Minas Gerais |
Moretti M.S.,Centro Universitario Vila Velha |
Goncalves Jr. J.F.,Federal University of Minas Gerais |
And 2 more authors.
Hydrobiologia | Year: 2010
The objective of this study was to evaluate the influences of detritus from the leaves of different species, and of exposure time on invertebrate colonization of leaves in a shaded Cerrado stream. We hypothesized that the exposure time is the main factor that influences the colonization of leaves by invertebrates. We used leaves of five tree species native to the Brazilian Cerrado: Protium heptaphyllum and Protium brasiliense (Burseraceae), Ocotea sp. (Lauraceae), Myrcia guyanensis (Myrtaceae), and Miconia chartacea (Melastomataceae), which are characterized by their toughness and low-nutritional quality. Litter bags, each containing leaves from one species, were placed in a headwater stream and removed after 7, 15, 30, 60, 90, and 120 days. The dominant taxon was Chironomidae, which comprised ca. 52% of all organisms and ca. 20% of the total biomass. The taxonomic richness of colonizing organisms did not vary among the leaf species. However, the density and biomass of the associated organisms varied differently among the kinds of detritus during the course of the incubation. The collector-gatherers and shredders reached higher densities in the detritus that decomposed more rapidly (Ocotea sp. and M. guyanensis), principally in the more advanced stages of colonization. The collector-filterers reached higher densities in the detritus that decomposed more slowly (P. heptaphyllum, P. brasiliense, and M. chartacea), principally in the initial stages of incubation. A cluster analysis divided the detritus samples of different leaf species according to the exposure time (initial phase: up to 7 days; intermediate phase: 7-30 days; advanced phase: 30-120 days), suggesting some succession in invertebrate colonization, with differences in taxon composition (indicator taxa analysis). These results suggest that regardless of the leaf-detritus species, exposure time was the main factor that influenced the colonization process of aquatic invertebrates. © 2010 Springer Science+Business Media B.V.
Brinn R.P.,Florida International University |
Marcon J.L.,Federal University of Amazonas |
McComb D.M.,Florida Atlantic University |
Gomes L.C.,Centro Universitario Vila Velha |
And 2 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2012
Potamotrygon cf. histrix (cururu stingray) are endemic freshwater stingrays from the middle region of the Rio Negro in the Brazilian Amazon basin and are exported worldwide as ornamentals caught by artisanal fishermen. The transport process from capture to final destination is long and stressful. This study quantified stress related changes in corticosterone, blood and water samples (baseline, pre-transport, 3h, 12h and 24h) analyzed during a transport experiment which tested two water additives (tetracycline and the probiotic Efinol®). There was a significant stepwise increase in corticosterone levels in stingrays over transport time in combination with osmoregulatory disturbances suggesting a stress related role of this corticosteroid. There were significant increases in water conductivity, Na + and K + losses and ammonia excretion. Blood parameters such as glucose, hematocrit, red blood count and urea did not change significantly during the experiment. Glucose levels did not increase significantly during transport and this may be due to the fact that other elasmobranchs have been shown to rely more on ketone bodies for energy rather than glucose and produce ammonia as their main nitrogenous waste. The mineralocorticoid action of this hormone has been shown in elasmobranchs and most likely plays a role in osmotic homeostasis. The use of probiotic and especially antibiotic should be avoided since no beneficial effects were observed. © 2011 Elsevier Inc.