High levels of genetic variability and panmixia of the tambaqui Colossoma macropomum (Cuvier, 1816) in the main channel of the Amazon River

Gonad differentiation in male zebrafish involves a transformation from a 'juvenile ovary' to testis. In our study, this phenomenon was analysed using a stable transgenic line ( vas::egfp ) created by Krovel & Olsen (Mechanisms of Development, 116: 141–150, 2002). Our data obtained by histological and immunohistochemical methods show that the onset of enhanced green fluorescent protein (EGFP) expression marks the conversion of the bipotential gonad into a 'juvenile ovary', and its subsequent decrease in the males indicates transformation into a testis. Furthermore, during the 'juvenile ovary' stage, a high level of variation was observed among individuals not only in the starting point and duration of EGFP expression but also in its intensity. The intensity of reporter expression in the males ranged from a high level of expression – similar to that observed in females – to invisible expression and correlated with the number of oocytes, the shape of 'juvenile ovary' and its lumen. Therefore, the authors conclude that although all males develop 'juvenile ovaries', they differ vastly in the extent of their commitment toward femaleness during this stage before testis differentiation. The differentiating zebrafish testis shows morphological features similar to those of the transforming gonad of protogynous hermaphrodites, and therefore, it could be a good model for the study of the process of female-to-male sex change in adult teleosts.     

A novel approach for the characterisation of proteoglycans and biosynthetic enzymes in a snail model

Proteoglycans encompass a heterogeneous group of glycoconjugates where proteins are substituted with linear, highly negatively charged glycosaminoglycan chains. Sulphated glycosaminoglycans are ubiquitous to the animal kingdom of the Eukarya domain. Information on the distribution and characterisation of proteoglycans in invertebrate tissues is limited and restricted to a few species. By the use of multidimensional protein identification technology and immunohistochemistry, this study shows for the first time the presence and tissue localisation of different proteoglycans, such as perlecan, aggrecan, and heparan sulphate proteoglycan, amongst others, in organs of the gastropoda Achatina fulica. Through a proteomic analysis of Golgi proteins and immunohistochemistry of tissue sections, we detected the machinery involved in glycosaminoglycan biosynthesis, related to polymer formation (polymerases), as well as secondary modifications (sulphation and uronic acid epimerization). Therefore, this work not only identifies both the proteoglycan core proteins and glycosaminoglycan biosynthetic enzymes in invertebrates but also provides a novel method for the study of glycosaminoglycan and proteoglycan evolution.     

Leaf defense syndromes in tropical ferns

Plant Ecology - Vascular plants exhibit defense syndromes, a variety of interdependent defensive traits against herbivores, which may considerably differ between plant groups. Although ferns are an...     

Trypanocidal action of eupomatenoid-5 is related to mitochondrion dysfunction and oxidative damage in Trypanosoma cruzi

Because of its severe side effects and variable efficacy, the current treatment for Chagas disease is unsatisfactory. Natural compounds are good alternative chemotherapeutic agents for the treatment of this infection. Recently, our group reported the antiproliferative activity and morphological alterations in epimastigotes and intracellular amastigotes of Trypanosoma cruzi treated with eupomatenoid-5, a neolignan isolated from leaves of Piper regnellii var. pallescens. Here, we demonstrate that eupomatenoid-5 exhibited activity against trypomastigotes, the infective form of T. cruzi (EC?? 40.5 μM), leading to ultrastructural alteration and lipoperoxidation in the cell membrane. Additionally, eupomatenoid-5 induced depolarization of the mitochondrial membrane, lipoperoxidation and increased G6PD activity in epimastigotes of T. cruzi. These findings support the possibility that different mechanisms may be targeted, according to the form of the parasite, and that the plasma membrane and mitochondria are the structures that are most affected in trypomastigotes and epimastigotes, respectively. Thus, the trypanocidal action of eupomatenoid-5 may be associated with mitochondrial dysfunction and oxidative damage, which can trigger destructive effects on biological molecules of T. cruzi, leading to parasite death.     

Prevalence of human papillomavirus (HPV) type 16 variants and rare HPV types in the central Amazon region

Infection by human papillomavirus (HPV) is one of the primary causes of mortality by cancer in northern Brazil. Sexually active women from Manaus, Amazonas, without cytological alterations and women with pre-malignant and malignant cytological alterations were examined for HPV virus, identified via PCR and sequencing. The target region for this study was part of the L1 capsid gene of HPV. Twenty-three samples that were PCR-positive were sequenced. Analysis of 336 bp demonstrated a high incidence of high-risk HPV types in the population of Manaus, identified as HPVs 16, 33, 58, 66, 68. HPV type 16 was the most prevalent, presenting two variants similar to the Asian-American (AA) and East-Asian type (As) variants. A rare HPV type 13 related to "Heck's disease" was also detected. This preliminary provides important information about the HPV circulating in Amazonas State.     

Sodium orthovanadate associated with pharmacological doses of ascorbate causes an increased generation of ROS in tumor cells that inhibits proliferation and triggers apoptosis

Pharmacological doses of ascorbate were evaluated for its ability to potentiate the toxicity of sodium orthovanadate (Na₃VO₄) in tumor cells. Cytotoxicity, inhibition of cell proliferation, generation of ROS and DNA fragmentation were assessed in T24 cells. Na₃VO₄ was cytotoxic against T24 cells (EC₅₀ = 5.8 μM at 24 h), but in the presence of ascorbate (100 μM) the EC₅₀ fell to 3.3 μM. Na₃VO₄ plus ascorbate caused a strong inhibition of cell proliferation (up to 20%) and increased the generation of ROS (4-fold). Na₃VO₄ did not directly cleave plasmid DNA, at this aspect no synergism was found occurring between Na₃VO₄ and ascorbate once the resulting action of the combination was no greater than that of both substances administered separately. Cells from Ehrlich ascites carcinoma-bearing mice were used to determine the activity of antioxidant enzymes, the extent of the oxidative damage and the type of cell death. Na₃VO₄ alone, or combined with ascorbate, increased catalase activity, but only Na₃VO₄ plus ascorbate increased superoxide dismutase activity (up to 4-fold). Oxidative damage on proteins and lipids was higher due to the treatment done with Na₃VO₄ plus ascorbate (2–3-fold). Ascorbate potentiated apoptosis in tumor cells from mice treated with Na₃VO₄. The results indicate that pharmacological doses of ascorbate enhance the generation of ROS induced by Na₃VO₄ in tumor cells causing inhibition of proliferation and apoptosis. Apoptosis induced by orthovanadate and ascorbate is closer related to inhibition on Bcl-xL and activation of Bax. Our data apparently rule out a mechanism of cell demise p53-dependent or related to Cdk2 impairment.     

The Histone Deacetylase Inhibitor Sodium Butyrate Promotes Cell Death and Differentiation and Reduces Neurosphere Formation in Human Medulloblastoma Cells

Increasing evidence suggests that alterations in epigenetic mechanisms regulating chromatin state play a role in the pathogenesis of medulloblastoma (MB), the most common malignant brain tumor of childhood. Histone deacetylase (HDAC) inhibitors, which increase chromatin relaxation, have been shown to display anticancer activities. Here we show that the HDAC inhibitor sodium butyrate (NaB) markedly increases cell death and reduces colony formation in human MB cell lines. In addition, NaB increased the mRNA expression of Gria2, a neuronal differentiation marker, in D283 and DAOY cells and reduced the number of neurospheres in D283 cell cultures. Finally, NaB reduced the viability of D283 cells when combined with etoposide. These data show that NaB displays pronounced inhibitory effects on the survival of human MB cells and suggest that NaB might potentiate the effects of etoposide. In addition, our study suggests that HDAC inhibition might promote the neuronal differentiation of MB cells and provides the first evidence that an HDAC inhibitor might suppress the expansion or survival of MB cancer stem cells.     

From river to farm: an evaluation of genetic diversity in wild and aquaculture stocks of <Emphasis Type="Italic">Brycon amazonicus</Emphasis> (Spix &; Agassiz, 1829), Characidae,Bryconinae

In Europe, the so-called Water Framework Directive was established to achieve a good ecological status of natural water bodies by 2015. In the case of heavily modified and artificial water bodies, the principle of a good ecological potential (GEP) applies. Methods have been developed for the evaluation of natural water bodies. However, these methods do not take the uniqueness of the assessment of heavily modified and artificial water bodies into consideration. On behalf of a working group on water issues of the federal states and the federal government (called LAWA), a nationwide assessment method of the GEP has been developed and its application has been verified within the framework of a practical project. Federal Waterways were not sufficiently considered. Hence we have been prompted to develop an assessment method for heavily modified and artificial water bodies, especially for federal waterways. Nearly 80% of the German federal water bodies are designated as heavily modified and artificial. The inclusion of federal waterways allows the unique characteristics of large rivers to be integrated in the methodological framework. Hereinafter, the results of the first working steps of the investigation as well as the methodological framework will be presented.