Cell viability in magnetotactic multicellular prokaryotes

A magnetotactic multicellular prokaryote (MMP) is an assembly of bacterial cells organized side by side in a hollow sphere in which each cell faces both the external environment and an internal acellular compartment in the center of the multicellular organism. MMPs swim as a unit propelled by the coordinated beating of the many flagella on the external surface of each cell. At every stage of its life cycle, MMPs are multicellular. Initially, a spherical MMP grows by enlarging the size of each of its cells, which then divide. Later, the cells separate into two identical spheres. Swimming individual cells of MMPs have never been observed. Here we have used fluorescent dyes and electron microscopy to study the viability of individual MMP cells. When separated from the MMP, the cells cease to move and they no longer respond to magnetic fields. Viability tests indicated that, although several cells could separate from a MMP before completely losing their motility and viability, all of the separated cells were dead. Our data show that the high level of cellular organization in MMPs is essential for their motility, magnetotactic behavior, and viability. [Int Microbiol 2006; 9(4):267-272

Salinity dependence of the distribution of multicellular magnetotactic prokaryotes in a hypersaline lagoon

Candidatus Magnetoglobus multicellularis is an unusual magnetotactic multicellular microorganism composed of a highly organized assemblage of gram-negative bacterial cells. In this work, the salinity dependence of Ca. M. multicellularis and its abundance in the hypersaline Araruama Lagoon, Brazil were studied. Viability experiments showed that Ca. M. multicellularis died in salinities >55‰ and < 40‰. Low salinities were also observed to modify the cellular assemblage. In microcosms prepared with different salinities, the microorganism grew better at intermediate salinities whereas in high or low salinities, the size of the population did not increase over time. The concentrations of Ca. M. multicellularis in the lagoon were related to salinity; sites with lower and higher salinities than the lagoon average contained less Ca. M. multicellularis. These results demonstrate the influence of salinity on the survival and distribution of Ca. M. multicellularis in the environment. In sediments, the abundance of Ca. M. multicellularis ranged from 0 to 103 microorganisms/ml, which represented 0.001% of the counts of total bacteria. The ability of Ca. M. multicellularis to accumulate iron and sulfur in high numbers of magnetosomes (up to 905 per microorganism) suggests that its impact on the sequestration of these elements (0.1% for biogenic bacterial iron) is not proportional to its abundance in the lagoon. [Int Microbiol 2009; 12(3):193-201

Spatiotemporal distribution of the magnetotactic multicellular prokaryote Candidatus Magnetoglobus multicellularis in a Brazilian hypersaline lagoon and in microcosms

Candidatus Magnetoglobus multicellularis is an unusual morphotype of magnetotactic prokaryotes. These microorganisms are composed of a spherical assemblage of gram-negative prokaryotic cells capable of swimming as a unitaligned along a magnetic field. While they occur in many aquatic habitats around the world, high numbers of Ca. M. multicellularishave been detected in Araruama Lagoon, a large hypersaline lagoon near the city of Rio de Janeiro, in Brazil. Here,we report on the spatiotemporal distribution of one such population in sediments of Araruama Lagoon, including its annualdistribution and its abundance compared with the total bacterial community. In microcosm experiments, Ca. M. multicellulariswas unable to survive for more than 45 days: the population density gradually decreased coinciding with a shift to theupper layers of the sediment. Nonetheless, Ca. M. multicellularis was detected throughout the year in all sites studied. Changes in the population density seemed to be related to the input of organic matter as well as to salinity. The populationdensity of Ca. M. multicellularis did not correlate with the total bacterial counts; instead, changes in the microbial communitystructure altered their counts in the environment. [Int Microbiol 2012; 15(3):141-149

Chondroitin sulfate immobilization at the surface of electrospun nanofiber meshes for cartilage regeneration

Aiming at improving the biocompatibility of biomaterial scaffolds, surface modification presents a way to preserve their mechanical properties and to improve the surface bioactivity. In this work, chondroitin sulfate (CS) was immobilized at the surface of electrospun poly(caprolactone) nanofiber meshes (PCL NFMs). The immobilization was performed with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS). Contact Angle, SEM, Optical Profilometry, FTIR, X-ray photoelectron spectroscopy techniques confirmed the CS-immobilization in PCL NFMs. Furthermore, CS-immobilized PCL NFMs showed lower roughness and higher hydrophilicity than the samples without CS. Human articular chondrocytes (HACs) were cultured on electrospun PCL NFMs with or without CS immobilization. It was observed that HACs proliferated through the entire time course of the experiment in both types of scaffolds. SEM observations revealed that HACs maintained their typical morphology and produced extracellular matrix. Glycosaminoglycans quantification showed increased values over time. Quantitative-PCR of cartilage-related genes revealed over-expression of Aggrecan, Collagen type II, COMP and Sox9 on both types of NFMs tested, with higher values for PCL. In conclusion, CS immobilization in PCL NFM was achieved successfully and provides a valid platform enabling further surface functionalization methods in scaffolds to be developed for cartilage tissue engineering

Circulating Senescent T Cells Are Linked to Systemic Inflammation and Lesion Size During Human Cutaneous Leishmaniasis

Leishmania (Viannia) braziliensis induces American tegumentary leishmaniasis that ranges in severity from the milder form, cutaneous (CL) to severe disseminated cutaneous leishmaniasis. Patients with CL develop a cell-mediated Th1 immune response accompanied by production of inflammatory cytokines, which contribute to parasite control and pathogenesis of disease. Here, we describe the accumulation of circulating T cells with multiple features of telomere dependent-senescence including elevated expression of CD57, KLRG-1, and γH2AX that have short telomeres and low hTERT expression during cutaneous L. braziliensis infection. This expanded population of T cells was found within the CD45RA+CD27− (EMRA) subset and produced high levels of inflammatory cytokines, analogous to the senescence-associated secretory profile (SASP) that has been described in senescent non-lymphoid cells. There was a significant correlation between the accumulation of these cells and the extent of systemic inflammation, suggesting that they are involved in the inflammatory response in this disease. Furthermore, these cells expressed high level of the skin homing receptor CLA and there was a highly significant correlation between the number of these cells in the circulation and the size of the Leishmania-induced lesions in the skin. Collectively our results suggest that extensive activation during the early stages of leishmaniasis drives the senescence of T cells with the propensity to home to the skin. The senescence-related inflammatory cytokine secretion by these cells may control the infection but also contribute to the immunopathology in the disease

Curcumin encapsulation in nanostructures for cancer therapy: a 10-year overview

Journal pre-proofsCurcumin (CUR) is a phenolic compound present in some herbs, including Curcuma longa Linn. (turmeric rhizome), with a high bioactive capacity and characteristic yellow color. It is mainly used as a spice, although it has been found that CUR has interesting pharmaceutical properties, acting as a natural antioxidant, anti-inflammatory, antimicrobial, and antitumoral agent. Nonetheless, CUR is a hydrophobic compound with low water solubility, poor chemical stability, and fast metabolism, limiting its use as a pharmacological compound. Smart drug delivery systems (DDS) have been used to overcome its low bioavailability and improve its stability. The current work overviews the literature from the past 10 years on the encapsulation of CUR in nanostructured systems, such as micelles, liposomes, niosomes, nanoemulsions, hydrogels, and nanocomplexes, emphasizing its use and ability in cancer therapy. The studies highlighted in this review have shown that these nanoformulations achieved higher solubility, improved tumor cytotoxicity, prolonged CUR release, and reduced side effects, among other interesting advantages.This study was funded by the Coordination for Higher Level Graduate Improvements (CAPES/Brazil, finance code 001), National Council for Scientific and Technological Development (CNPq/Brazil, PIBIC process #123483/2020-4), State of São Paulo Research Foundation (FAPESP/Brazil, processes #2017/10789-1, #2018/10799-0, #2018/06475-4, #2018/07707-6, #2019/08549-8, and #2020/03727-2). This work was also supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and the project AgriFood XXI (NORTE-01-0145-FEDER-000041) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Our Figures were created with BioRenderinfo:eu-repo/semantics/publishedVersio

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors