Population structure and gene flow of the yellow anaconda (Eunectes notaeus) in northern Argentina

Yellow anacondas (Eunectes notaeus) are large, semiaquatic boid snakes found in wetland systems in South America. These snakes are commercially harvested under a sustainable management plan in Argentina, so information regarding population structuring can be helpful for determination of management units. We evaluated genetic structure and migration using partial sequences from the mitochondrial control region and mitochondrial genes cyt-b and ND4 for 183 samples collected within northern Argentina. A group of landscape features and environmental variables including several treatments of temperature and precipitation were explored as potential drivers of observed genetic patterns. We found significant population structure between most putative population comparisons and bidirectional but asymmetric migration in several cases. The configuration of rivers and wetlands was found to be significantly associated with yellow anaconda population structure (IBD), and important for gene flow, although genetic distances were not significantly correlated with the environmental variables used here. More in-depth analyses of environmental data may be needed to fully understand the importance of environmental conditions on population structure and migration. These analyses indicate that our putative populations are demographically distinct and should be treated as such in Argentina's management plan for the harvesting of yellow anacondas.     

Identification and characterization of a novel calcium-activated apyrase from Cryptosporidium parasites and its potential role in pathogenesis

Herein, we report the biochemical and functional characterization of a novel Ca(2+)-activated nucleoside diphosphatase (apyrase), CApy, of the intracellular gut pathogen Cryptosporidium. The purified recombinant CApy protein displayed activity, substrate specificity and calcium dependency strikingly similar to the previously described human apyrase, SCAN-1 (soluble calcium-activated nucleotidase 1). CApy was found to be expressed in both Cryptosporidium parvum oocysts and sporozoites, and displayed a polar localization in the latter, suggesting a possible co-localization with the apical complex of the parasite. In vitro binding experiments revealed that CApy interacts with the host cell in a dose-dependent fashion, implying the presence of an interacting partner on the surface of the host cell. Antibodies directed against CApy block Cryptosporidium parvum sporozoite invasion of HCT-8 cells, suggesting that CApy may play an active role during the early stages of parasite invasion. Sequence analyses revealed that the capy gene shares a high degree of homology with apyrases identified in other organisms, including parasites, insects and humans. Phylogenetic analysis argues that the capy gene is most likely an ancestral feature that has been lost from most apicomplexan genomes except Cryptosporidium, Neospora and Toxoplasma.     

Cisplatin-mediated impairment of mitochondrial DNA metabolism inversely correlates with glutathione levels

Cisplatin accumulates in mitochondria, which are a major target for this drug in cancer cells. Thus alterations in mitochondrial function have been implicated in cancer cell resistance to chemotherapeutic agents. Moreover, cisplatin toxic side effects seem to be associated with mitochondrial injury in vivo and in vitro. In order to clarify the potential effect of cisplatin in mtDNA (mitochondrial DNA) maintenance and expression, we have analysed rat liver mtDNA and mtRNA (mitochondrial RNA) synthesis as well as their stability under the influence of in vivo treatment or in vitro exposure to cisplatin. We show that cisplatin causes a direct and significant impairment of mtDNA and mtRNA synthesis and decreases steady-state levels of mtRNAs in isolated mitochondria. Furthermore, in vivo treatment of the animals with cisplatin exerts a protective effect from the impairment of mtRNA metabolism caused by in vitro exposure to the drug, by means of increased mitochondrial GSH levels after in vivo cisplatin treatment.     

QSAR modeling and transmission electron microscopy stereology of altered mitochondrial ultrastructure of white blood cells in patients diagnosed as schizophrenic and treated with antipsychotic drugs.

Treatment of patients diagnosed as schizophrenic with antipsychotic drugs (neuroleptics) is known to cause occasional unexplained depletion of white blood cells, especially neutrophil granulocytes. It has been known for many years that neuroleptics can interfere with the mitochondrial respiratory chain in vitro. Because there has been a growing interest recently in mitochondrial targeting of drugs, and since a quantitative structure-activity relationship (QSAR) model that predicts mitochondrial accumulation of neuroleptics has been published, we investigated the effects of neuroleptics on white blood cell mitochondria. Venous blood samples were collected from both patients undergoing treatment with neuroleptics and healthy volunteers. The samples were processed for transmission electron microscopy. The resulting images of white blood cells were analyzed using stereology to compare quantitatively mitochondrial morphology in the patient and control groups. We found that in patients, but not in controls, there was swelling of mitochondria and fragmentation of the mitochondrial cristae. There also were fewer mitochondria in patients than in controls, although due to the swelling of the organelles, the volume density of mitochondria in the two groups was not significantly different. Such changes are typical of a toxic insult. Consequently, it seems plausible that, since schizophrenia is not a disease considered to affect white blood cells per se, these changes probably are due to the medication.     

Brucella abortus MFP: a trimeric coiled-coil protein with membrane fusogenic activity

The bacterial genus Brucella consists of a group of facultative intracellular pathogens which produces abortion and infertility in animals and a chronic debilitating febrile illness in humans. BMFP is a basic protein of Brucella abortus that belongs to a highly conserved group of homologue proteins of unknown structure and function in proteobacteria (COG2960). In this study, we report the structural and biochemical characterization of this protein. We found that BMFP has two structural domains: a carboxyl-terminal coiled-coil domain through which the protein self-associates as a trimer and a natively disordered amino-terminal domain which has propensity to adopt an amphipathic alpha-helical structure. This natively unfolded domain undergoes a structural rearrangement from unfolded to alpha-helix in the presence of high ionic strength, acidic pH, detergents, and phospholipid vesicles. Moreover, we demonstrated that the interaction of BMFP with phospholipid vesicles promotes in vitro membrane fusion. These results contribute to the elucidation of the structural and functional properties of this protein and its homologues present in most proteobacteria.     

Multisite Image Data Collection and Management Using the RSNA Image Sharing Network

The execution of a multisite trial frequently includes image collection. The Clinical Trials Processor (CTP) makes removal of protected health information highly reliable. It also provides reliable transfer of images to a central review site. Trials using central review of imaging should consider using CTP for handling image data when a multisite trial is being designed.     

Effects of inter-annual temperature variability,including ENSO and post-ENSO events,on reproductive traits in the tunicate Pyura praeputialis

Reproduction in tunicates is considered to be particularly vulnerable to changes in seawater temperature. In the present study we investigated the effects of sea surface temperature and temperature anomalies on reproductive traits of the non-native sessile tunicate Pyura praeputialis. Reproductive traits of this species were investigated over the course of 67 months, based on samples collected at two localities (eastern and western shorelines) of the Bay of Antofagasta. The study period included years with different oceanic and atmospheric conditions: a warm event, El Niño (June 1997 to July 1998); a cold event, La Niña (August 1998 to December 2000); and post-La Niña (January 2000 to December 2002). We compared two common indices (condition and gonadosomatic) and histological sections to evaluate the maximum reproduction index of this introduced species that dominates a large part of the rocky intertidal habitat in the Bay of Antofagasta. We found sexually mature individuals all year-round and a decrease in both reproductive indices matching the reduction in the sea surface temperature during the austral autumn and winter months. The results suggest that gonad development in this species is sensitive to sea surface temperature and thermal anomalies. We conclude that future thermal anomalies or projected global average sea surface warming associated with climate change might have no negative consequences on these reproductive traits of P. praeputialis. This suggests this species is ecologically resilient and that the ecosystem services that this species provides for other invertebrate and algal species will be maintained.     

New insights on the trophic ecology of blue (Prionace glauca) and shortfin mako sharks (Isurus oxyrinchus) from the oceanic eastern South Pacific

The blue shark (Prionace glauca) and the shortfin mako shark (Isurus oxyrinchus) are two large and highly migratory sharks distributed in most oceans. Although they are often caught in the south Pacific Ocean long-line fisheries, their trophic ecology is poorly understood. Stable isotopes with Bayesian mixing and dependence concentration models were performed to determine the diet and trophic differences between the two species in the South-eastern Pacific Ocean. According to the mixing models, fishes are the most important prey of these sharks. Dolphin calves and remains were found in the stomachs of both species, which represents a novel finding in trophic ecology of South Pacific sharks. Intra-specific differences were found in P. glauca, but not in specimens of I. oxyrinchus. The two sharks showed a high degree of diet overlap (73%), primarily over mackerel and dolphin carcasses. Our results indicate that blue and shortfin mako sharks have a generalist feeding strategy in the eastern Pacific Ocean, with a strong preference for teleost fishes and also for dolphin carcasses. Therefore, trophic studies are useful to understand energy flow through the food web, and the trophic position of key species.