Cryptic lineages and Pleistocene population expansion in a Brazilian Cerrado frog

Diversification of South American species endemic to open habitats has been attributed to both Tertiary events and Pleistocene climatic fluctuations. Nonetheless, phylogeographical studies of taxa in these regions are few, precluding generalizations about the timing and processes leading to differentiation and speciation. We inferred population structure of Hypsiboas albopunctatus, a frog widely distributed in the Brazilian Cerrado. Three geographically distinct lineages were recovered in our phylogeny. The Chapada dos Guimarães (CG) clade was the first to diverge from other populations and contains multiple haplotypes from a single population in western Cerrado, probably representing a cryptic species. The southeast clade (SE) includes populations along the southeastern limit of the range within the historical distribution of the Brazilian Atlantic forest. Finally, the Central Cerrado (CC) group includes haplotypes from the interior of Brazil that are paraphyletic relative to the SE clade. Analyses of historical demography indicate significant population expansion in the CC and SE populations, likely associated with colonization of newly formed open habitats. The divergence of populations in the CG clade occurred in the late Miocene, concordant with the uplift of the central Brazilian plateau. Divergence of the SE clade from the CC occurred during the mid‐Pleistocene. Thus, both Tertiary geological events and Pleistocene climatic fluctuations promoted divergences among lineages. Our study reveals a complex history of diversification in the Cerrado, a morphoclimatic domain highly threatened because of anthropogenic habitat alteration. We identified surprisingly deep divergences in a widely distributed frog, indicating that the Cerrado is not a barrier‐free habitat and that its diversity is likely underestimated.     

Recent colonization of the Galápagos by the tree Geoffroea spinosa Jacq. (Leguminosae)

This study puts together genetic data and an approximate bayesian computation (ABC) approach to infer the time at which the tree Geoffroea spinosa colonized the Galápagos Islands. The genetic diversity and differentiation between Peru and Galápagos population samples, estimated using three chloroplast spacers and six microsatellite loci, reveal significant differences between two mainland regions separated by the Andes mountains (Inter Andean vs. Pacific Coast) as well as a significant genetic differentiation of island populations. Microsatellites identify two distinct geographical clusters, the Galápagos and the mainland, and chloroplast markers show a private haplotype in the Galápagos. The nuclear distinctiveness of the Inter Andean populations suggests current restricted pollen flow, but chloroplast points to cross‐Andean dispersals via seeds, indicating that the Andes might not be an effective biogeographical barrier. The ABC analyses clearly point to the colonization of the Galápagos within the last 160 000 years and possibly as recently as 4750 years ago (475 generations). Founder events associated with colonization of the two islands where the species occurs are detected, with Española having been colonized after Floreana. We discuss two nonmutually exclusive possibilities for the colonization of the Galápagos, recent natural dispersal vs. human introduction.     

Cytoskeleton alterations induced by Geodia corticostylifera depsipeptides in breast cancer cells

Crude extracts of the marine sponge Geodia corticostylifera from Brazilian Coast have previously shown antibacterial, antifungal, cytotoxic, haemolytic and neurotoxic activities. The present work describes the isolation of the cyclic peptides geodiamolides A, B, H and I (1-4) from G. corticostylifera and their anti-proliferative effects against sea urchin eggs and human breast cancer cell lineages. Its structure-activity relationship is discussed as well. In an initial series of experiments these peptides inhibited the first cleavage of sea urchin eggs (Lytechinus variegatus). Duplication of nuclei without complete egg cell division indicated the mechanism of action might be related to microfilament disruption. Further studies showed that the geodiamolides have anti-proliferative activity against human breast cancer cell lines (T47D and MCF7). Using fluorescence techniques and confocal microscopy, we found evidence that the geodiamolides A, B, H and I act by disorganizing actin filaments of T47D and MCF7 cancer cells, in a way similar to other depsipeptides (such as jaspamide 5 and dolastatins), keeping the normal microtubule organization. Normal cells lines (primary culture human fibroblasts and BRL3A rat liver epithelial cells) were not affected by the treatment as tumor cells were, thus indicating the biomedical potential of these compounds.     

DNA topoisomerase I from parasitic protozoa: a potential target for chemotherapy

The growing occurrence of drug resistant strains of unicellular prokaryotic parasites, along with insecticide-resistant vectors, are the factors contributing to the increased prevalence of tropical diseases in underdeveloped and developing countries, where they are endemic. Malaria, cryptosporidiosis, African and American trypanosomiasis and leishmaniasis threaten human beings, both for the high mortality rates involved and the economic loss resulting from morbidity. Due to the fact that effective immunoprophylaxis is not available at present; preventive sanitary measures and pharmacological approaches are the only sources to control the undesirable effects of such diseases. Current anti-parasitic chemotherapy is expensive, has undesirable side effects or, in many patients, is only marginally effective. Under this point of view molecular biology techniques and drug discovery must walk together in order to find new targets for chemotherapy intervention. The identification of DNA topoisomerases as a promising drug target is based on the clinical success of camptothecin derivatives as anticancer agents. The recent detection of substantial differences between trypanosome and leishmania DNA topoisomerase IB with respect to their homologues in mammals has provided a new lead in the study of the structural determinants that can be effectively targeted. The present report is an up to date review of the new findings on type IB DNA topoisomerase in unicellular parasites and the role of these enzymes as targets for therapeutic agents.     

Distribution of pteridophyte communities along environmental gradients in Central Amazonia, Brazil

Extrapolation of local abundance–environment relationships to broader scales provides species distribution models used for conservation planning. We investigated the importance of environmental heterogeneity and geographic distance on pteridophyte species spatial distribution on 38 plots of 250 × 2.5 m distributed over 90 km² in Central Amazon. Inclusion of canopy openness in our models increased the capacity of predicting community composition even under the narrow range of canopy openness found in our plots. Nevertheless, there was still a large amount of unexplained variance (55–65%). The response of the community to the light gradient was hierarchical and we did not find evidences of light partitioning. Most species were concentrated in low light plots but a few common and abundant occurred along the entire gradient. Soil properties were the major determinants of community composition. Contrary to similar studies, slope was not a good predictor of pteridophyte community composition, indicating that this relationship may be site-specific. There was no correlation between floristic distances and geographic distances. We concluded that mesoscale turnover is low, although locally environmental variation determines high turnover of species. Studies among different Amazonian physiognomies tend to find high levels of beta-diversity. However, coarse comparisons can not reveal subtle patterns that are relevant for biodiversity conservation planning. This study found some important changes on pteridophyte community within the same type of forest, mainly related to environmental heterogeneity, even in narrow ranges of environmental variation.     

Radiation therapy with curative intention in men with de novo metastatic prostate carcinoma: shoot‘em all!

BackgroundAbout 5% of prostate cancer cases are metastatic at diagnoses. Radiotherapy of both primary tumor and secondary lesions can be, in addition to systemic treatments, a radical alternative for selected patients.Materials and methodsPatients with de novo prostate carcinoma with bone or lymph node metastases were retrospectively reviewed. All patients received moderate hypofractionated IMRT/VMAT up to 63 Gy in 21 daily fractions of 3 Gy to prostate and metastases with neoadjuvant and concurrent androgen deprivation therapy (ADT). According to known advances some patients also received abiraterone, enzalutamide, or docetaxel.ResultsBetween 2015–2020, we attended 26 prostate cancer patients (median age 69.5 years, range 52–84) with simultaneous oligometastases [mean 2.1 metastases, median 1.5 metastases (range 1–6)]. Eighteen patients (69%) presented lymph node metastases, 4 (15.5%) bone metastases and 4 (15.5%) both lymph node and bone metastases. With a median follow-up of 15.5 months (range 3–65 months), 16 patients (62%) are alive and tumor free while 10 (38%) are alive with tumor. Four patients (17%) developed tumor progression, out of irradiated area in all cases, with a median time to progression of 43.5 months (range 27–56 months). Actuarial progression-free survival (PFS) rates at 12 and 24 months were 94.1% and 84.7%, respectively. No grade > 2 acute or late complications were recorded.ConclusionsSimultaneous directed radical hypofractionated radiation therapy for prostate and metastases is feasible, well tolerated and achieves an acceptable PFS rate. However, further studies with longer follow-up are necessary to definitively address these observations.     

Imbalance between matrix metalloproteinases and tissue inhibitor of metalloproteinases in hypertensive vascular remodeling

Structural vascular changes in two-kidney, one-clip (2K-1C) hypertension may result from increased matrix metalloproteinase (MMP)-2 activity. MMP-2 activation is regulated by other MMPs, including transmembrane-MMPs, and by tissue inhibitors of MMPs (TIMPs). We have investigated the localization of MMP-2, -9, -14, and TIMPs 1–4 in hypertensive aortas and measured their levels by zymography/Western blotting and immunohistochemistry. Gelatinolytic activity was assayed in tissues by in situ zymography. Sham-operated and 2K-1C hypertensive rats were treated with doxycycline (or vehicle) for 8 weeks, and the systolic blood pressure was monitored weekly. Doxycycline attenuated 2K-1C hypertension (165 ± 11.7 mmHg versus 213 ± 7.9 mm Hg in hypertensive controls, P < 0.01), and completely prevented increase in the thicknesses of the media and the intima in 2K-1C animals (P < 0.01). Increased amounts of MMP-2, -9, and -14 were found in hypertensive aortas, as well as enhanced gelatinolytic activity. A gradient in the localization of MMP-2, -9, and -14 was found, with increased amounts detected in the intima, at sites with higher gelatinolytic activity. Doxycycline attenuated hypertension induced increases in all the 3 investigated MMPs in both the media and the intima (all P < 0.05), but it did not change the amounts of TIMPs 1–4 (P > 0.05). Therefore, an imbalance between increased amounts of MMPs at the tissue level without a corresponding increase in the quantities of TIMPs, particularly in the intima and inner media layers, appears to account for the increased proteolytic activity found in 2K-1C hypertension-induced maladaptive vascular remodeling.