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PfEMP1 (erythrocyte membrane protein 1) adhesins play a pivotal role in the pathophysiology of falciparum malaria, by mediating sequestration of Plasmodium falciparum-infected erythrocytes in the microvasculature. PfEMP1 variants are expressed by var genes and are presented on membrane elevations, termed knobs. However, the organization of PfEMP1 on knobs is largely unclear. Here, we use super-resolution microscopy and genetically altered parasites expressing a modified var2csa gene in which the coding sequence of the photoactivatable mEOS2 was inserted to determine the number and distribution of PfEMP1 on single knobs. The data were verified by quantitative fluorescence-activated cell sorting analysis and immuno-electron microscopy together with stereology methods. We show that knobs contain 3.3 ± 1.7 and 4.3 ± 2.5 PfEMP1 molecules, predominantly placed on the knob tip, in parasitized erythrocytes containing wild type and sickle haemoglobin, respectively. The ramifications of our findings for cytoadhesion and immune evasion are discussed.
Metastasic breast cancer is the leading cause of death by malignancy in women worldwide. Tumor metastasis is a multistep process encompassing local invasion of cancer cells at primary tumor site, intravasation into the blood vessel, survival in systemic circulation, and extravasation across the endothelium to metastasize at a secondary site. However, only a small percentage of circulating cancer cells initiate metastatic colonies. This fact, together with the inaccessibility and structural complexity of target tissues has hampered the study of the later steps in cancer metastasis. In addition, most data are derived from in vivo models where critical steps such as intravasation/extravasation of human cancer cells are mediated by murine endothelial cells. Here, we developed a new mouse model to study the molecular and cellular mechanisms underlying late steps of the metastatic cascade. We have shown that a network of functional human blood vessels can be formed by co-implantation of human endothelial cells and mesenchymal cells, embedded within a reconstituted basement membrane-like matrix and inoculated subcutaneously into immunodeficient mice. The ability of circulating cancer cells to colonize these human vascularized organoids was next assessed in an orthotopic model of human breast cancer by bioluminescent imaging, molecular techniques and immunohistological analysis. We demonstrate that disseminated human breast cancer cells efficiently colonize organoids containing a functional microvessel network composed of human endothelial cells, connected to the mouse circulatory system. Human breast cancer cells could be clearly detected at different stages of the metastatic process: initial arrest in the human microvasculature, extravasation, and growth into avascular micrometastases. This new mouse model may help us to map the extravasation process with unprecedented detail, opening the way for the identification of relevant targets for therapeutic intervention.
Samples collected in Central Asia, Kyrgyzstan, have revealed a hitherto unknown diversity of Campodeidae (Diplura) in soil and cave habitats, including a new genus and species, Kyrgyzstancampa sanare Sendra & Ferreira gen. et sp. nov., Turkmenocampa edaphica Sendra & Sánchez-García sp. nov. and a previously recognized soil-dwelling species, Campodea (Dicampa) catalana Denis, 1930. Kyrgyzstancampa sanare Sendra & Ferreira gen. et sp. nov. was collected in the deep zone of an interesting geological and cultural cave, Ak-Turpak Cave, located near the western margin of Kadamjay District, Batken Province. This genus belongs to the subfamily Campodeinae, sharing the morphology of the pretarsus with Eutrichocampa and other related genera, but differing from them in the shape of the claws and the laminar lateral processes, in addition to its unique cupuliform organ and the macrosetal pattern on the thorax and abdomen. Turkmenocampa edaphica Sendra & Sánchez-García sp. nov. was found in humid edaphic habitats, under stones or near roots, and is morphologically and geographically very similar to the cave-dwelling species Turkmenicampa mirabilis Sendra #38; Stoev, 2017, which occurs in an isolated cave in the nearby country of Turkmenistan.
Few species of Japygidae (Diplura) have been discovered in cave ecosystems despite their importance as large predators. A small collection of rare specimens of this hexapod group has allowed to explore the taxonomy of japygids from caves in New Zealand, Morocco and South Africa, and to describe one new genus: Imazighenjapyx Sendra & Sánchez-García gen. nov., as well as four new species: Austrjapyx wynbergensis Sendra & Sánchez-García sp. nov., Imazighenjapyx marocanus Sendra & Sánchez-García gen. et sp. nov., Opisthjapyx naledi Sendra & Sánchez-García sp. nov. and Teljapyx aotearoa Sendra & Sánchez-García sp. nov. For each of the new taxa we give a comprehensive description of their habitats. These new findings resulted in a revision of the distribution and allowed to re-evaluate the morphological traits of the fifteen cave-adapted japygids species already known worldwide. The functional morphology of the remarkable abdominal pincers of Japygidae and their adaptation to predation are discussed, as well as their potential role in mating behaviour.
The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.