Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs

Immunity and vaccine development efforts against Trypanosoma cruzi

Artículo de revisión especializadoTrypanosoma cruzi (T. cruzi) is the causative agent for Chagas disease (CD). There is a critical lack of methods for prevention of infection or treatment of acute infection and chronic disease. Studies in experimental models have suggested that the protective immunity against T. cruzi infection requires the elicitation of Th1 cytokines, lytic antibodies and the concerted activities of macrophages, T helper cells, and cytotoxic T lymphocytes (CTLs). In this review, we summarize the research efforts in vaccine development to date and the challenges faced in achieving an efficient prophylactic or therapeutic vaccine against human CD.UTM

Structure-based design of a eukaryote-selective antiprotozoal fluorinated aminoglycoside

This work was supported by Grant‐in‐Aid for Young Scientists (B) (No. 26860025) and Grant‐in‐Aid for Scientific Research (C) (No. 17K08248) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), and partially supported by the Kurata Grant awarded by the Kurata Memorial Hitachi Science and Technology Foundation, the grant provided by the Ichiro Kanehara Foundation and the Platform for Drug Discovery, Informatics, and Structural Life Science from Japan Agency for Medical Research and Development (AMED). H.K. was supported by the Sasakawa Scientific Research Grant from the Japan Science Society and the SUNBOR Scholarship. We thank the Photon Factory for provision of synchrotron radiation facilities (Photon Factory Proposal No. 2014G532) and acknowledge the staff of the NW‐12A and BL‐17A beamlines. We thank our colleague Vu Linh Ly for preparing the hydroxysisomicin intermediate. The Montreal group thanks NSERC for financial support and a fellowship to J.P.M. from the Québec Research Fund: Nature and Technology. The T.K.S. group thanks the Medical Research Council (MR/M020118/1) for current financial support.Aminoglycosides (AG) are antibiotics that lower the accuracy of protein synthesis by targeting a highly conserved RNA helix of the ribosomal A-site. The discovery of AGs that selectively target the eukaryotic ribosome, but lack activity in prokaryotes, are promising as antiprotozoals for the treatment of neglected tropical diseases, and as therapies to read-through point-mutation genetic diseases. However, a single nucleobase change A1408G in the eukaryotic A-site leads to negligible affinity for most AGs. Herein we report the synthesis of 6-fluorosisomicin, the first 6-fluorinated aminoglycoside, which specifically interacts with the protozoal cytoplasmic rRNA A-site, but not the bacterial A-site, as evidenced by X-ray co-crystal structures. The respective dispositions of 6-fluorosisomicin within the bacterial and protozoal A-sites reveal that the fluorine atom acts only as a hydrogen-bond acceptor to favorably interact with G1408 of the protozoal A-site. Unlike aminoglycosides containing a 6-ammonium group, 6-fluorosisomicin cannot participate in the hydrogen-bonding pattern that characterizes stable pseudo-base-pairs with A1408 of the bacterial A-sites. Based on these structural observations it may be possible to shift the biological activity of aminoglycosides to act preferentially as antiprotozoal agents. These findings expand the repertoire of small molecules targeting the eukaryotic ribosome and demonstrate the usefulness of fluorine as a design element.PostprintPeer reviewe

Classification of the Immune Composition in the Tumor Infiltrate.

Flow cytometry is one of the most suitable techniques for analyzing and classifying different cell suspensions derived from blood or others compartments. The characterization of all different cellular subtypes is made with different antibodies that detect surface or intracytoplasmic antigens. Here we describe the technique to thoroughly characterize immune cells from tumor infiltrates and proceed to isolation using single-cell sorting

Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs

Road towards development of new antimalarial: organelle associated metabolic pathways in Plasmodium as drug targets and discovery of lead drug candidates

Malaria remains a global threat with millions of deaths annually. Emergence of parasite strains resistant to widely used antimalarials, including the artemisinin combination therapy (ACT), and the absence of an effective vaccine makes treatment of malaria difficult than ever before. The need of the hour is to re-evaluate the chemotherapeutic approach and to identify new drug targets and develop new pharmacophores against the parasite. An important approach for antimalarial drug discovery is to understand critical metabolic pathways in the parasite which may help us to identify critical targets in the parasites and design specific inhibitors for these targets. Here, we have discussed proteins and pathways in different parasite organelles, i.e. apicoplast, mitochondrial and food vacuole, which have been suggested as potential drug targets; these unique parasite proteins can be targeted to develop new and novel antimalarials. In addition, we have also discussed several antimalarial projects currently under different stages of drug development pipeline. These promising antimalarial compounds have the potential to overcome multidrug resistance. Ongoing global efforts to develop new antimalarials and to identify drug targets suggest a promising future on malaria elimination and eradication